Add m-esr52 at 52.6.0

19 files changed, 3728 insertions, 0 deletions

diff --git a/netwerk/socket/moz.build b/netwerk/socket/moz.build
new file mode 100644
index 000000000..34361a10c
--- /dev/null
+++ b/netwerk/socket/moz.build
@@ -0,0 +1,37 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsISocketProvider.idl',
+    'nsISocketProviderService.idl',
+    'nsISOCKSSocketInfo.idl',
+    'nsISSLSocketControl.idl',
+    'nsITransportSecurityInfo.idl',
+]
+
+XPIDL_MODULE = 'necko_socket'
+
+LOCAL_INCLUDES += [
+    '/netwerk/base',
+]
+
+UNIFIED_SOURCES += [
+    'nsSocketProviderService.cpp',
+    'nsSOCKSIOLayer.cpp',
+    'nsSOCKSSocketProvider.cpp',
+    'nsUDPSocketProvider.cpp',
+]
+
+if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
+    XPIDL_SOURCES += [
+        'nsINamedPipeService.idl',
+    ]
+    UNIFIED_SOURCES += [
+        'nsNamedPipeIOLayer.cpp',
+        'nsNamedPipeService.cpp'
+    ]
+
+FINAL_LIBRARY = 'xul'
diff --git a/netwerk/socket/nsINamedPipeService.idl b/netwerk/socket/nsINamedPipeService.idl
new file mode 100644
index 000000000..9db557577
--- /dev/null
+++ b/netwerk/socket/nsINamedPipeService.idl
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+#include "nsrootidl.idl"
+
+/**
+ * nsINamedPipeDataObserver
+ *
+ * This is the callback interface for nsINamedPipeService.
+ * The functions are called by the internal thread in the nsINamedPipeService.
+ */
+[scriptable, uuid(de4f460b-94fd-442c-9002-1637beb2185a)]
+interface nsINamedPipeDataObserver : nsISupports
+{
+    /**
+     * onDataAvailable
+     *
+     * @param aBytesTransferred
+     *        Transfered bytes during last transmission.
+     * @param aOverlapped
+     *        Corresponding overlapped structure used by the async I/O
+     */
+    void onDataAvailable(in unsigned long aBytesTransferred,
+                         in voidPtr aOverlapped);
+
+    /**
+     * onError
+     *
+     * @param aError
+     *        Error code of the error.
+     * @param aOverlapped
+     *        Corresponding overlapped structure used by the async I/O
+     */
+    void onError(in unsigned long aError,
+                 in voidPtr aOverlapped);
+};
+
+/**
+ * nsINamedPipeService
+ */
+[scriptable, uuid(1bf19133-5625-4ac8-836a-80b1c215f72b)]
+interface nsINamedPipeService : nsISupports
+{
+    /**
+     * addDataObserver
+     *
+     * @param aHandle
+     *        The handle that is going to be monitored for read/write operations.
+     *        Only handles that are opened with overlapped IO are supported.
+     * @param aObserver
+     *        The observer of the handle, the service strong-refs of the observer.
+     */
+    void addDataObserver(in voidPtr aHandle,
+                         in nsINamedPipeDataObserver aObserver);
+
+    /**
+     * removeDataObserver
+     *
+     * @param aHandle
+              The handle associated to the observer, and will be closed by the
+              service.
+     * @param aObserver
+     *        The observer to be removed.
+     */
+    void removeDataObserver(in voidPtr aHandle,
+                            in nsINamedPipeDataObserver aObserver);
+
+    /**
+     * isOnCurrentThread
+     *
+     * @return the caller runs within the internal thread.
+     */
+    boolean isOnCurrentThread();
+};
diff --git a/netwerk/socket/nsISOCKSSocketInfo.idl b/netwerk/socket/nsISOCKSSocketInfo.idl
new file mode 100644
index 000000000..b17176f53
--- /dev/null
+++ b/netwerk/socket/nsISOCKSSocketInfo.idl
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+%{ C++
+namespace mozilla {
+namespace net {
+union NetAddr;
+}
+}
+%}
+[ptr] native NetAddrPtr(mozilla::net::NetAddr);
+
+[scriptable, uuid(D5C0D1F9-22D7-47DC-BF91-D9AC6E1251A6)]
+interface nsISOCKSSocketInfo : nsISupports
+{
+    [noscript] attribute NetAddrPtr destinationAddr;
+    [noscript] attribute NetAddrPtr externalProxyAddr;
+    [noscript] attribute NetAddrPtr internalProxyAddr;
+};
diff --git a/netwerk/socket/nsISSLSocketControl.idl b/netwerk/socket/nsISSLSocketControl.idl
new file mode 100644
index 000000000..b8c2b4184
--- /dev/null
+++ b/netwerk/socket/nsISSLSocketControl.idl
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIInterfaceRequestor;
+interface nsIX509Cert;
+
+%{C++
+#include "nsTArrayForwardDeclare.h"
+class nsCString;
+%}
+[ref] native nsCStringTArrayRef(nsTArray<nsCString>);
+
+[scriptable, builtinclass, uuid(418265c8-654e-4fbb-ba62-4eed27de1f03)]
+interface nsISSLSocketControl : nsISupports {
+    attribute nsIInterfaceRequestor     notificationCallbacks;
+
+    void proxyStartSSL();
+    void StartTLS();
+
+    /* NPN (Next Protocol Negotiation) is a mechanism for
+       negotiating the protocol to be spoken inside the SSL
+       tunnel during the SSL handshake. The NPNList is the list
+       of offered client side protocols. setNPNList() needs to
+       be called before any data is read or written (including the
+       handshake to be setup correctly. The server determines the
+       priority when multiple matches occur, but if there is no overlap
+       the first protocol in the list is used. */
+
+    [noscript] void setNPNList(in nsCStringTArrayRef aNPNList);
+
+    /* negotiatedNPN is '' if no NPN list was provided by the client,
+     * or if the server did not select any protocol choice from that
+     * list. That also includes the case where the server does not
+     * implement NPN.
+     *
+     * If negotiatedNPN is read before NPN has progressed to the point
+     * where this information is available NS_ERROR_NOT_CONNECTED is
+     * raised.
+     */
+    readonly attribute ACString negotiatedNPN;
+
+    /* For 0RTT we need to know the alpn protocol selected for the last tls
+     * session. This function will return a value if applicable or an error
+     * NS_ERROR_NOT_AVAILABLE.
+     */
+    ACString getAlpnEarlySelection();
+
+    /* If 0RTT handshake was applied and some data has been sent, as soon as
+     * the handshake finishes this attribute will be set to appropriate value.
+     */
+    readonly attribute bool earlyDataAccepted;
+
+    /* When 0RTT is performed, PR_Write will not drive the handshake forward.
+     * It must be forced by calling this function.
+     */
+    void driveHandshake();
+
+    /* Determine if a potential SSL connection to hostname:port with
+     * a desired NPN negotiated protocol of npnProtocol can use the socket
+     * associated with this object instead of making a new one.
+     */
+    boolean joinConnection(
+      in ACString npnProtocol, /* e.g. "spdy/2" */
+      in ACString hostname,
+      in long port);
+
+    /* Determine if existing connection should be trusted to convey information about
+     * a hostname.
+     */
+    boolean isAcceptableForHost(in ACString hostname);
+
+    /* The Key Exchange Algorithm is used when determining whether or
+       not HTTP/2 can be used.
+
+       After a handshake is complete it can be read from KEAUsed.
+       The values correspond to the SSLKEAType enum in NSS or the
+       KEY_EXCHANGE_UNKNOWN constant defined below.
+
+       KEAKeyBits is the size/security-level used for the KEA.
+    */
+
+    [infallible] readonly attribute short KEAUsed;
+    [infallible] readonly attribute unsigned long KEAKeyBits;
+
+    const short KEY_EXCHANGE_UNKNOWN = -1;
+
+    /*
+     * The original flags from the socket provider.
+     */
+    readonly attribute uint32_t providerFlags;
+
+    /* These values are defined by TLS. */
+    const short SSL_VERSION_3   = 0x0300;
+    const short TLS_VERSION_1   = 0x0301;
+    const short TLS_VERSION_1_1 = 0x0302;
+    const short TLS_VERSION_1_2 = 0x0303;
+    const short TLS_VERSION_1_3 = 0x0304;
+    const short SSL_VERSION_UNKNOWN = -1;
+
+    [infallible] readonly attribute short SSLVersionUsed;
+    [infallible] readonly attribute short SSLVersionOffered;
+
+    /* These values match the NSS defined values in sslt.h */
+    const short SSL_MAC_UNKNOWN = -1;
+    const short SSL_MAC_NULL    = 0;
+    const short SSL_MAC_MD5     = 1;
+    const short SSL_MAC_SHA     = 2;
+    const short SSL_HMAC_MD5    = 3;
+    const short SSL_HMAC_SHA    = 4;
+    const short SSL_HMAC_SHA256 = 5;
+    const short SSL_MAC_AEAD    = 6;
+
+    [infallible] readonly attribute short MACAlgorithmUsed;
+
+    /**
+     * If set before the server requests a client cert (assuming it does so at
+     * all), then this cert will be presented to the server, instead of asking
+     * the user or searching the set of rememebered user cert decisions.
+     */
+    attribute nsIX509Cert clientCert;
+
+    /**
+     * bypassAuthentication is true if the server certificate checks are
+     * not be enforced. This is to enable non-secure transport over TLS.
+     */
+    [infallible] readonly attribute boolean bypassAuthentication;
+
+    /*
+     * failedVerification is true if any enforced certificate checks have failed.
+     * Connections that have not yet tried to verify, have verifications bypassed,
+     * or are using acceptable exceptions will all return false.
+     */
+    [infallible] readonly attribute boolean failedVerification;
+};
+
diff --git a/netwerk/socket/nsISocketProvider.idl b/netwerk/socket/nsISocketProvider.idl
new file mode 100644
index 000000000..19b010eda
--- /dev/null
+++ b/netwerk/socket/nsISocketProvider.idl
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIProxyInfo;
+[ptr] native PRFileDescStar(struct PRFileDesc);
+native NeckoOriginAttributes(mozilla::NeckoOriginAttributes);
+[ref] native const_OriginAttributesRef(const mozilla::NeckoOriginAttributes);
+
+%{ C++
+#include "mozilla/BasePrincipal.h"
+%}
+
+/**
+ * nsISocketProvider
+ */
+[scriptable, uuid(508d5469-9e1e-4a08-b5b0-7cfebba1e51a)]
+interface nsISocketProvider : nsISupports
+{
+    /**
+     * newSocket
+     *
+     * @param aFamily
+     *        The address family for this socket (PR_AF_INET or PR_AF_INET6).
+     * @param aHost
+     *        The origin hostname for this connection.
+     * @param aPort
+     *        The origin port for this connection.
+     * @param aProxyHost
+     *        If non-null, the proxy hostname for this connection.
+     * @param aProxyPort
+     *        The proxy port for this connection.
+     * @param aFlags
+     *        Control flags that govern this connection (see below.)
+     * @param aFileDesc
+     *        The resulting PRFileDesc.
+     * @param aSecurityInfo
+     *        Any security info that should be associated with aFileDesc.  This
+     *        object typically implements nsITransportSecurityInfo.
+     */
+    [noscript]
+    void newSocket(in long                      aFamily,
+                   in string                    aHost, 
+                   in long                      aPort,
+                   in nsIProxyInfo              aProxy,
+                   in const_OriginAttributesRef aOriginAttributes,
+                   in unsigned long             aFlags,
+                   out PRFileDescStar           aFileDesc, 
+                   out nsISupports              aSecurityInfo);
+
+    /**
+     * addToSocket
+     *
+     * This function is called to allow the socket provider to layer a
+     * PRFileDesc on top of another PRFileDesc.  For example, SSL via a SOCKS
+     * proxy.
+     *
+     * Parameters are the same as newSocket with the exception of aFileDesc,
+     * which is an in-param instead.
+     */
+    [noscript]
+    void addToSocket(in long                      aFamily,
+                     in string                    aHost, 
+                     in long                      aPort,
+                     in nsIProxyInfo              aProxy,
+                     in const_OriginAttributesRef aOriginAttributes,
+                     in unsigned long             aFlags,
+                     in PRFileDescStar            aFileDesc, 
+                     out nsISupports              aSecurityInfo);
+
+    /**
+     * PROXY_RESOLVES_HOST
+     *
+     * This flag is set if the proxy is to perform hostname resolution instead
+     * of the client.  When set, the hostname parameter passed when in this
+     * interface will be used instead of the address structure passed for a
+     * later connect et al. request.
+     */
+    const long PROXY_RESOLVES_HOST = 1 << 0;
+    
+    /**
+     * When setting this flag, the socket will not apply any
+     * credentials when establishing a connection. For example,
+     * an SSL connection would not send any client-certificates
+     * if this flag is set.
+     */
+    const long ANONYMOUS_CONNECT = 1 << 1;
+
+    /**
+     * If set, indicates that the connection was initiated from a source
+     * defined as being private in the sense of Private Browsing. Generally,
+     * there should be no state shared between connections that are private
+     * and those that are not; it is OK for multiple private connections
+     * to share state with each other, and it is OK for multiple non-private
+     * connections to share state with each other.
+     */
+    const unsigned long NO_PERMANENT_STORAGE = 1 << 2;
+
+    /**
+     * This flag is an explicit opt-in that allows a normally secure socket
+     * provider to use, at its discretion, an insecure algorithm. e.g.
+     * a TLS socket without authentication.
+     */
+    const unsigned long MITM_OK = 1 << 3;
+
+    /**
+     * If set, do not use newer protocol features that might have interop problems
+     * on the Internet. Intended only for use with critical infra like the updater.
+     * default is false.
+     */
+    const unsigned long BE_CONSERVATIVE = 1 << 4;
+};
+
+%{C++
+/**
+ * nsISocketProvider implementations should be registered with XPCOM under a
+ * contract ID of the form: "@mozilla.org/network/socket;2?type=foo"
+ */
+#define NS_NETWORK_SOCKET_CONTRACTID_PREFIX \
+    "@mozilla.org/network/socket;2?type="
+%}
diff --git a/netwerk/socket/nsISocketProviderService.idl b/netwerk/socket/nsISocketProviderService.idl
new file mode 100644
index 000000000..db38d299a
--- /dev/null
+++ b/netwerk/socket/nsISocketProviderService.idl
@@ -0,0 +1,20 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsISocketProvider;
+
+/**
+ * nsISocketProviderService
+ *
+ * Provides a mapping between a socket type and its associated socket provider
+ * instance.  One could also use the service manager directly.
+ */
+[scriptable, uuid(8f8a23d0-5472-11d3-bbc8-0000861d1237)]
+interface nsISocketProviderService : nsISupports
+{
+    nsISocketProvider getSocketProvider(in string socketType);
+};
diff --git a/netwerk/socket/nsITransportSecurityInfo.idl b/netwerk/socket/nsITransportSecurityInfo.idl
new file mode 100644
index 000000000..bec59c8e5
--- /dev/null
+++ b/netwerk/socket/nsITransportSecurityInfo.idl
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIX509CertList;
+
+[scriptable, uuid(216112d3-28bc-4671-b057-f98cc09ba1ea)]
+interface nsITransportSecurityInfo : nsISupports {
+    readonly attribute unsigned long    securityState;
+    readonly attribute wstring          errorMessage;
+    readonly attribute long             errorCode; // PRErrorCode
+
+    /**
+     * If certificate verification failed, this will be the peer certificate
+     * chain provided in the handshake, so it can be used for error reporting.
+     * If verification succeeded, this will be null.
+     */
+    readonly attribute nsIX509CertList failedCertChain;
+};
+
diff --git a/netwerk/socket/nsNamedPipeIOLayer.cpp b/netwerk/socket/nsNamedPipeIOLayer.cpp
new file mode 100644
index 000000000..6de51ea1c
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeIOLayer.cpp
@@ -0,0 +1,952 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+#include <utility>
+#include "mozilla/Atomics.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Logging.h"
+#include "mozilla/Move.h"
+#include "mozilla/net/DNS.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Unused.h"
+#include "nsINamedPipeService.h"
+#include "nsISupportsImpl.h"
+#include "nsIThread.h"
+#include "nsNamedPipeIOLayer.h"
+#include "nsNetCID.h"
+#include "nspr.h"
+#include "nsServiceManagerUtils.h"
+#include "nsSocketTransportService2.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "private/pprio.h"
+
+namespace mozilla {
+namespace net {
+
+static mozilla::LazyLogModule gNamedPipeLog("NamedPipeWin");
+#define LOG_NPIO_DEBUG(...) MOZ_LOG(gNamedPipeLog, mozilla::LogLevel::Debug, \
+                                    (__VA_ARGS__))
+#define LOG_NPIO_ERROR(...) MOZ_LOG(gNamedPipeLog, mozilla::LogLevel::Error, \
+                                    (__VA_ARGS__))
+
+PRDescIdentity nsNamedPipeLayerIdentity;
+static PRIOMethods nsNamedPipeLayerMethods;
+
+class NamedPipeInfo final : public nsINamedPipeDataObserver
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSINAMEDPIPEDATAOBSERVER
+
+  explicit NamedPipeInfo();
+
+  nsresult Connect(const nsACString& aPath);
+  nsresult Disconnect();
+
+  /**
+   * Both blocking/non-blocking mode are supported in this class.
+   * The default mode is non-blocking mode, however, the client may change its
+   * mode to blocking mode during hand-shaking (e.g. nsSOCKSSocketInfo).
+   *
+   * In non-blocking mode, |Read| and |Write| should be called by clients only
+   * when |GetPollFlags| reports data availability. That is, the client calls
+   * |GetPollFlags| with |PR_POLL_READ| and/or |PR_POLL_WRITE| set, and
+   * according to the flags that set, |GetPollFlags| will check buffers status
+   * and decide corresponding actions:
+   *
+   * -------------------------------------------------------------------
+   * |               | data in buffer          | empty buffer          |
+   * |---------------+-------------------------+-----------------------|
+   * | PR_POLL_READ  | out: PR_POLL_READ       | DoRead/DoReadContinue |
+   * |---------------+-------------------------+-----------------------|
+   * | PR_POLL_WRITE | DoWrite/DoWriteContinue | out: PR_POLL_WRITE    |
+   * ------------------------------------------+------------------------
+   *
+   * |DoRead| and |DoWrite| initiate read/write operations asynchronously, and
+   * the |DoReadContinue| and |DoWriteContinue| are used to check the amount
+   * of the data are read/written to/from buffers.
+   *
+   * The output parameter and the return value of |GetPollFlags| are identical
+   * because we don't rely on the low-level select function to wait for data
+   * availability, we instead use nsNamedPipeService to poll I/O completeness.
+   *
+   * When client get |PR_POLL_READ| or |PR_POLL_WRITE| from |GetPollFlags|,
+   * they are able to use |Read| or |Write| to access the data in the buffer,
+   * and this is supposed to be very fast because no network traffic is involved.
+   *
+   * In blocking mode, the flow is quite similar to non-blocking mode, but
+   * |DoReadContinue| and |DoWriteContinue| are never been used since the
+   * operations are done synchronously, which could lead to slow responses.
+   */
+  int32_t Read(void* aBuffer, int32_t aSize);
+  int32_t Write(const void* aBuffer, int32_t aSize);
+
+  // Like Read, but doesn't remove data in internal buffer.
+  uint32_t Peek(void* aBuffer, int32_t aSize);
+
+  // Number of bytes available to read in internal buffer.
+  int32_t Available() const;
+
+  // Flush write buffer
+  //
+  // @return whether the buffer has been flushed
+  bool Sync(uint32_t aTimeout);
+  void SetNonblocking(bool nonblocking);
+
+  bool IsConnected() const;
+  bool IsNonblocking() const;
+  HANDLE GetHandle() const;
+
+  // Initiate and check current status for read/write operations.
+  int16_t GetPollFlags(int16_t aInFlags, int16_t* aOutFlags);
+
+private:
+  virtual ~NamedPipeInfo();
+
+  /**
+   * DoRead/DoWrite starts a read/write call synchronously or asynchronously
+   * depending on |mNonblocking|. In blocking mode, they return when the action
+   * has been done and in non-blocking mode it returns the number of bytes that
+   * were read/written if the operation is done immediately. If it takes some
+   * time to finish the operation, zero is returned and
+   * DoReadContinue/DoWriteContinue must be called to get async I/O result.
+   */
+  int32_t DoRead();
+  int32_t DoReadContinue();
+  int32_t DoWrite();
+  int32_t DoWriteContinue();
+
+  /**
+   * There was a write size limitation of named pipe,
+   * see https://support.microsoft.com/en-us/kb/119218 for more information.
+   * The limitation no longer exists, so feel free to change the value.
+   */
+  static const uint32_t kBufferSize = 65536;
+
+  nsCOMPtr<nsINamedPipeService> mNamedPipeService;
+
+  HANDLE mPipe; // the handle to the named pipe.
+  OVERLAPPED mReadOverlapped; // used for asynchronous read operations.
+  OVERLAPPED mWriteOverlapped;  // used for asynchronous write operations.
+
+  uint8_t mReadBuffer[kBufferSize]; // octets read from pipe.
+
+  /**
+   * These indicates the [begin, end) position of the data in the buffer.
+   */
+  DWORD mReadBegin;
+  DWORD mReadEnd;
+
+  bool mHasPendingRead; // previous asynchronous read is not finished yet.
+
+  uint8_t mWriteBuffer[kBufferSize]; // octets to be written to pipe.
+
+  /**
+   * These indicates the [begin, end) position of the data in the buffer.
+   */
+  DWORD mWriteBegin; // how many bytes are already written.
+  DWORD mWriteEnd; // valid amount of data in the buffer.
+
+  bool mHasPendingWrite; // previous asynchronous write is not finished yet.
+
+  /**
+   * current blocking mode is non-blocking or not, accessed only in socket
+   * thread.
+   */
+  bool mNonblocking;
+
+  Atomic<DWORD> mErrorCode; // error code from Named Pipe Service.
+};
+
+NS_IMPL_ISUPPORTS(NamedPipeInfo,
+                  nsINamedPipeDataObserver)
+
+NamedPipeInfo::NamedPipeInfo()
+  : mNamedPipeService(do_GetService(NS_NAMEDPIPESERVICE_CONTRACTID))
+  , mPipe(INVALID_HANDLE_VALUE)
+  , mReadBegin(0)
+  , mReadEnd(0)
+  , mHasPendingRead(false)
+  , mWriteBegin(0)
+  , mWriteEnd(0)
+  , mHasPendingWrite(false)
+  , mNonblocking(true)
+  , mErrorCode(0)
+{
+  MOZ_ASSERT(mNamedPipeService);
+
+  ZeroMemory(&mReadOverlapped, sizeof(OVERLAPPED));
+  ZeroMemory(&mWriteOverlapped, sizeof(OVERLAPPED));
+}
+
+NamedPipeInfo::~NamedPipeInfo()
+{
+  MOZ_ASSERT(!mPipe);
+}
+
+// nsINamedPipeDataObserver
+
+NS_IMETHODIMP
+NamedPipeInfo::OnDataAvailable(uint32_t aBytesTransferred,
+                               void* aOverlapped)
+{
+  DebugOnly<bool> isOnPipeServiceThread;
+  MOZ_ASSERT(NS_SUCCEEDED(mNamedPipeService->IsOnCurrentThread(&isOnPipeServiceThread)) &&
+             isOnPipeServiceThread);
+
+  if (aOverlapped == &mReadOverlapped) {
+    LOG_NPIO_DEBUG("[%s] %p read %d bytes", __func__, this, aBytesTransferred);
+  } else if (aOverlapped == &mWriteOverlapped) {
+    LOG_NPIO_DEBUG("[%s] %p write %d bytes", __func__, this, aBytesTransferred);
+  } else {
+    MOZ_ASSERT(false, "invalid callback");
+    mErrorCode = ERROR_INVALID_DATA;
+    return NS_ERROR_FAILURE;
+  }
+
+  mErrorCode = ERROR_SUCCESS;
+
+  // dispatch an empty event to trigger STS thread
+  gSocketTransportService->Dispatch(NS_NewRunnableFunction([]{}),
+                                    NS_DISPATCH_NORMAL);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+NamedPipeInfo::OnError(uint32_t aError,
+                       void* aOverlapped)
+{
+  DebugOnly<bool> isOnPipeServiceThread;
+  MOZ_ASSERT(NS_SUCCEEDED(mNamedPipeService->IsOnCurrentThread(&isOnPipeServiceThread)) &&
+             isOnPipeServiceThread);
+
+  LOG_NPIO_ERROR("[%s] error code=%d", __func__, aError);
+  mErrorCode = aError;
+
+  // dispatch an empty event to trigger STS thread
+  gSocketTransportService->Dispatch(NS_NewRunnableFunction([]{}),
+                                    NS_DISPATCH_NORMAL);
+
+  return NS_OK;
+}
+
+// Named pipe operations
+
+nsresult
+NamedPipeInfo::Connect(const nsACString& aPath)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  HANDLE pipe;
+  nsAutoCString path(aPath);
+
+  pipe = CreateFileA(path.get(),
+                     GENERIC_READ | GENERIC_WRITE,
+                     FILE_SHARE_READ | FILE_SHARE_WRITE,
+                     nullptr,
+                     OPEN_EXISTING,
+                     FILE_FLAG_OVERLAPPED,
+                     nullptr);
+
+  if (pipe == INVALID_HANDLE_VALUE) {
+    LOG_NPIO_ERROR("[%p] CreateFile error (%d)", this, GetLastError());
+    return NS_ERROR_FAILURE;
+  }
+
+  DWORD pipeMode = PIPE_READMODE_MESSAGE;
+  if (!SetNamedPipeHandleState(pipe, &pipeMode, nullptr, nullptr)) {
+    LOG_NPIO_ERROR("[%p] SetNamedPipeHandleState error (%d)",
+                   this,
+                   GetLastError());
+    CloseHandle(pipe);
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv = mNamedPipeService->AddDataObserver(pipe, this);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    CloseHandle(pipe);
+    return rv;
+  }
+
+  HANDLE readEvent = CreateEventA(nullptr, TRUE, TRUE, "NamedPipeRead");
+  if (NS_WARN_IF(!readEvent || readEvent == INVALID_HANDLE_VALUE)) {
+    CloseHandle(pipe);
+    return NS_ERROR_FAILURE;
+  }
+
+  HANDLE writeEvent = CreateEventA(nullptr, TRUE, TRUE, "NamedPipeWrite");
+  if (NS_WARN_IF(!writeEvent || writeEvent == INVALID_HANDLE_VALUE)) {
+    CloseHandle(pipe);
+    CloseHandle(readEvent);
+    return NS_ERROR_FAILURE;
+  }
+
+  mPipe = pipe;
+  mReadOverlapped.hEvent = readEvent;
+  mWriteOverlapped.hEvent = writeEvent;
+  return NS_OK;
+}
+
+nsresult
+NamedPipeInfo::Disconnect()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  nsresult rv = mNamedPipeService->RemoveDataObserver(mPipe, this);
+  NS_WARN_IF(NS_FAILED(rv));
+  mPipe = nullptr;
+
+  if (mReadOverlapped.hEvent &&
+      mReadOverlapped.hEvent != INVALID_HANDLE_VALUE) {
+    CloseHandle(mReadOverlapped.hEvent);
+    mReadOverlapped.hEvent = nullptr;
+  }
+
+  if (mWriteOverlapped.hEvent &&
+      mWriteOverlapped.hEvent != INVALID_HANDLE_VALUE) {
+    CloseHandle(mWriteOverlapped.hEvent);
+    mWriteOverlapped.hEvent = nullptr;
+  }
+
+  return NS_OK;
+}
+
+int32_t
+NamedPipeInfo::Read(void* aBuffer, int32_t aSize)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  int32_t bytesRead = Peek(aBuffer, aSize);
+
+  if (bytesRead > 0) {
+    mReadBegin += bytesRead;
+  }
+
+  return bytesRead;
+}
+
+int32_t
+NamedPipeInfo::Write(const void* aBuffer, int32_t aSize)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(mWriteBegin <= mWriteEnd);
+
+  if (!IsConnected()) {
+    // pipe unconnected
+    PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+    return -1;
+  }
+
+  if (mWriteBegin == mWriteEnd) {
+    mWriteBegin = mWriteEnd = 0;
+  }
+
+  int32_t bytesToWrite = std::min<int32_t>(aSize,
+                                           sizeof(mWriteBuffer) - mWriteEnd);
+  MOZ_ASSERT(bytesToWrite >= 0);
+
+  if (bytesToWrite == 0) {
+    PR_SetError(IsNonblocking() ? PR_WOULD_BLOCK_ERROR
+                                : PR_IO_PENDING_ERROR,
+                0);
+    return -1;
+  }
+
+  memcpy(&mWriteBuffer[mWriteEnd], aBuffer, bytesToWrite);
+  mWriteEnd += bytesToWrite;
+
+  /**
+   * Triggers internal write operation by calling |GetPollFlags|.
+   * This is required for callers that use blocking I/O because they don't call
+   * |GetPollFlags| to write data, but this also works for non-blocking I/O.
+   */
+  int16_t outFlag;
+  GetPollFlags(PR_POLL_WRITE, &outFlag);
+
+  return bytesToWrite;
+}
+
+uint32_t
+NamedPipeInfo::Peek(void* aBuffer, int32_t aSize)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(mReadBegin <= mReadEnd);
+
+  if (!IsConnected()) {
+    // pipe unconnected
+    PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+    return -1;
+  }
+
+  /**
+   * If there's nothing in the read buffer, try to trigger internal read
+   * operation by calling |GetPollFlags|. This is required for callers that
+   * use blocking I/O because they don't call |GetPollFlags| to read data,
+   * but this also works for non-blocking I/O.
+   */
+  if (!Available()) {
+    int16_t outFlag;
+    GetPollFlags(PR_POLL_READ, &outFlag);
+
+    if (!(outFlag & PR_POLL_READ)) {
+      PR_SetError(IsNonblocking() ? PR_WOULD_BLOCK_ERROR
+                                  : PR_IO_PENDING_ERROR,
+                  0);
+      return -1;
+    }
+  }
+
+  // Available() can't return more than what fits to the buffer at the read offset.
+  int32_t bytesRead = std::min<int32_t>(aSize, Available());
+  MOZ_ASSERT(bytesRead >= 0);
+  MOZ_ASSERT(mReadBegin + bytesRead <= mReadEnd);
+  memcpy(aBuffer, &mReadBuffer[mReadBegin], bytesRead);
+  return bytesRead;
+}
+
+int32_t
+NamedPipeInfo::Available() const
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(mReadBegin <= mReadEnd);
+  MOZ_ASSERT(mReadEnd - mReadBegin <= 0x7FFFFFFF); // no more than int32_max
+  return mReadEnd - mReadBegin;
+}
+
+bool
+NamedPipeInfo::Sync(uint32_t aTimeout)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  if (!mHasPendingWrite) {
+    return true;
+  }
+  return WaitForSingleObject(mWriteOverlapped.hEvent, aTimeout) == WAIT_OBJECT_0;
+}
+
+void
+NamedPipeInfo::SetNonblocking(bool nonblocking)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  mNonblocking = nonblocking;
+}
+
+bool
+NamedPipeInfo::IsConnected() const
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  return mPipe && mPipe != INVALID_HANDLE_VALUE;
+}
+
+bool
+NamedPipeInfo::IsNonblocking() const
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  return mNonblocking;
+}
+
+HANDLE
+NamedPipeInfo::GetHandle() const
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  return mPipe;
+}
+
+
+int16_t
+NamedPipeInfo::GetPollFlags(int16_t aInFlags, int16_t* aOutFlags)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  *aOutFlags = 0;
+
+  if (aInFlags & PR_POLL_READ) {
+    int32_t bytesToRead = 0;
+    if (mReadBegin < mReadEnd) { // data in buffer and is ready to be read
+      bytesToRead = Available();
+    } else if (mHasPendingRead) { // nonblocking I/O and has pending task
+      bytesToRead = DoReadContinue();
+    } else { // read bufer is empty.
+      bytesToRead = DoRead();
+    }
+
+    if (bytesToRead > 0) {
+      *aOutFlags |= PR_POLL_READ;
+    } else if (bytesToRead < 0) {
+      *aOutFlags |= PR_POLL_ERR;
+    }
+  }
+
+  if (aInFlags & PR_POLL_WRITE) {
+    int32_t bytesWritten = 0;
+    if (mHasPendingWrite) { // nonblocking I/O and has pending task.
+      bytesWritten = DoWriteContinue();
+    } else if (mWriteBegin < mWriteEnd) { // data in buffer, ready to write
+      bytesWritten = DoWrite();
+    } else { // write buffer is empty.
+      *aOutFlags |= PR_POLL_WRITE;
+    }
+
+    if (bytesWritten < 0) {
+      *aOutFlags |= PR_POLL_ERR;
+    } else if (bytesWritten &&
+               !mHasPendingWrite &&
+               mWriteBegin == mWriteEnd) {
+      *aOutFlags |= PR_POLL_WRITE;
+    }
+  }
+
+  return *aOutFlags;
+}
+
+// @return: data has been read and is available
+int32_t
+NamedPipeInfo::DoRead()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(!mHasPendingRead);
+  MOZ_ASSERT(mReadBegin == mReadEnd); // the buffer should be empty
+
+  mReadBegin = 0;
+  mReadEnd = 0;
+
+  BOOL success = ReadFile(mPipe,
+                          mReadBuffer,
+                          sizeof(mReadBuffer),
+                          &mReadEnd,
+                          IsNonblocking() ? &mReadOverlapped : nullptr);
+
+  if (success) {
+    LOG_NPIO_DEBUG("[%s][%p] %d bytes read", __func__, this, mReadEnd);
+    return mReadEnd;
+  }
+
+  switch (GetLastError()) {
+    case ERROR_MORE_DATA:   // has more data to read
+      mHasPendingRead = true;
+      return DoReadContinue();
+
+    case ERROR_IO_PENDING:  // read is pending
+      mHasPendingRead = true;
+      break;
+
+    default:
+      LOG_NPIO_ERROR("[%s] ReadFile failed (%d)", __func__, GetLastError());
+      Disconnect();
+      PR_SetError(PR_IO_ERROR, 0);
+      return -1;
+  }
+
+  return 0;
+}
+
+int32_t
+NamedPipeInfo::DoReadContinue()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(mHasPendingRead);
+  MOZ_ASSERT(mReadBegin == 0 && mReadEnd == 0);
+
+  BOOL success;
+  success = GetOverlappedResult(mPipe,
+                                &mReadOverlapped,
+                                &mReadEnd,
+                                FALSE);
+  if (success) {
+    mHasPendingRead = false;
+    if (mReadEnd == 0) {
+      Disconnect();
+      PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+      return -1;
+    }
+
+    LOG_NPIO_DEBUG("[%s][%p] %d bytes read", __func__, this, mReadEnd);
+    return mReadEnd;
+  }
+
+  switch (GetLastError()) {
+    case ERROR_MORE_DATA:
+      mHasPendingRead = false;
+      LOG_NPIO_DEBUG("[%s][%p] %d bytes read", __func__, this, mReadEnd);
+      return mReadEnd;
+    case ERROR_IO_INCOMPLETE: // still in progress
+      break;
+    default:
+      LOG_NPIO_ERROR("[%s]: GetOverlappedResult failed (%d)",
+                     __func__,
+                     GetLastError());
+      Disconnect();
+      PR_SetError(PR_IO_ERROR, 0);
+      return -1;
+  }
+
+  return 0;
+}
+
+int32_t
+NamedPipeInfo::DoWrite()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(!mHasPendingWrite);
+  MOZ_ASSERT(mWriteBegin < mWriteEnd);
+
+  DWORD bytesWritten = 0;
+  BOOL success = WriteFile(mPipe,
+                           &mWriteBuffer[mWriteBegin],
+                           mWriteEnd - mWriteBegin,
+                           &bytesWritten,
+                           IsNonblocking() ? &mWriteOverlapped : nullptr);
+
+  if (success) {
+    mWriteBegin += bytesWritten;
+    LOG_NPIO_DEBUG("[%s][%p] %d bytes written", __func__, this, bytesWritten);
+    return bytesWritten;
+  }
+
+  if (GetLastError() != ERROR_IO_PENDING) {
+    LOG_NPIO_ERROR("[%s] WriteFile failed (%d)", __func__, GetLastError());
+    Disconnect();
+    PR_SetError(PR_IO_ERROR, 0);
+    return -1;
+  }
+
+  mHasPendingWrite = true;
+
+  return 0;
+}
+
+int32_t
+NamedPipeInfo::DoWriteContinue()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_ASSERT(mHasPendingWrite);
+
+  DWORD bytesWritten = 0;
+  BOOL success = GetOverlappedResult(mPipe,
+                                     &mWriteOverlapped,
+                                     &bytesWritten,
+                                     FALSE);
+
+  if (!success) {
+    if (GetLastError() == ERROR_IO_INCOMPLETE) {
+      // still in progress
+      return 0;
+    }
+
+    LOG_NPIO_ERROR("[%s] GetOverlappedResult failed (%d)",
+                   __func__,
+                   GetLastError());
+    Disconnect();
+    PR_SetError(PR_IO_ERROR, 0);
+    return -1;
+  }
+
+  mHasPendingWrite = false;
+  mWriteBegin += bytesWritten;
+  LOG_NPIO_DEBUG("[%s][%p] %d bytes written", __func__, this, bytesWritten);
+  return bytesWritten;
+}
+
+static inline NamedPipeInfo*
+GetNamedPipeInfo(PRFileDesc* aFd)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  MOZ_DIAGNOSTIC_ASSERT(aFd);
+  MOZ_DIAGNOSTIC_ASSERT(aFd->secret);
+  MOZ_DIAGNOSTIC_ASSERT(PR_GetLayersIdentity(aFd) == nsNamedPipeLayerIdentity);
+
+  if (!aFd ||
+      !aFd->secret ||
+      PR_GetLayersIdentity(aFd) != nsNamedPipeLayerIdentity) {
+    LOG_NPIO_ERROR("cannot get named pipe info");
+    return nullptr;
+  }
+
+  return reinterpret_cast<NamedPipeInfo*>(aFd->secret);
+}
+
+static PRStatus
+nsNamedPipeConnect(PRFileDesc* aFd,
+                   const PRNetAddr* aAddr,
+                   PRIntervalTime aTimeout)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return PR_FAILURE;
+  }
+
+  if (NS_WARN_IF(NS_FAILED(info->Connect(
+      nsDependentCString(aAddr->local.path))))) {
+    return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+static PRStatus
+nsNamedPipeConnectContinue(PRFileDesc* aFd, PRInt16 aOutFlags)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  return PR_SUCCESS;
+}
+
+static PRStatus
+nsNamedPipeClose(PRFileDesc* aFd)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  if (aFd->secret && PR_GetLayersIdentity(aFd) == nsNamedPipeLayerIdentity) {
+    RefPtr<NamedPipeInfo> info = dont_AddRef(GetNamedPipeInfo(aFd));
+    info->Disconnect();
+    aFd->secret = nullptr;
+    aFd->identity = PR_INVALID_IO_LAYER;
+  }
+
+  MOZ_ASSERT(!aFd->lower);
+  PR_DELETE(aFd);
+
+  return PR_SUCCESS;
+}
+
+static PRInt32
+nsNamedPipeSend(PRFileDesc* aFd,
+                const void* aBuffer,
+                PRInt32 aAmount,
+                PRIntn aFlags,
+                PRIntervalTime aTimeout)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  Unused << aFlags;
+  Unused << aTimeout;
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return info->Write(aBuffer, aAmount);
+}
+
+static PRInt32
+nsNamedPipeRecv(PRFileDesc* aFd,
+                void* aBuffer,
+                PRInt32 aAmount,
+                PRIntn aFlags,
+                PRIntervalTime aTimeout)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  Unused << aTimeout;
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+
+  if (aFlags) {
+    if (aFlags != PR_MSG_PEEK) {
+      PR_SetError(PR_UNKNOWN_ERROR, 0);
+      return -1;
+    }
+    return info->Peek(aBuffer, aAmount);
+  }
+
+  return info->Read(aBuffer, aAmount);
+}
+
+static inline PRInt32
+nsNamedPipeRead(PRFileDesc* aFd, void* aBuffer, PRInt32 aAmount)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return info->Read(aBuffer, aAmount);
+}
+
+static inline PRInt32
+nsNamedPipeWrite(PRFileDesc* aFd, const void* aBuffer, PRInt32 aAmount)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return info->Write(aBuffer, aAmount);
+}
+
+static PRInt32
+nsNamedPipeAvailable(PRFileDesc* aFd)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return static_cast<PRInt32>(info->Available());
+}
+
+static PRInt64
+nsNamedPipeAvailable64(PRFileDesc* aFd)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return -1;
+  }
+  return static_cast<PRInt64>(info->Available());
+}
+
+static PRStatus
+nsNamedPipeSync(PRFileDesc* aFd)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return PR_FAILURE;
+  }
+  return info->Sync(0) ? PR_SUCCESS : PR_FAILURE;
+}
+
+static PRInt16
+nsNamedPipePoll(PRFileDesc* aFd, PRInt16 aInFlags, PRInt16* aOutFlags)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  NamedPipeInfo* info = GetNamedPipeInfo(aFd);
+  if (!info) {
+    PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    return 0;
+  }
+  return info->GetPollFlags(aInFlags, aOutFlags);
+}
+
+// FIXME: remove socket option functions?
+static PRStatus
+nsNamedPipeGetSocketOption(PRFileDesc* aFd, PRSocketOptionData* aData)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  MOZ_ASSERT(aFd);
+  MOZ_ASSERT(aData);
+
+  switch (aData->option) {
+    case PR_SockOpt_Nonblocking:
+      aData->value.non_blocking = GetNamedPipeInfo(aFd)->IsNonblocking()
+                                  ? PR_TRUE
+                                  : PR_FALSE;
+      break;
+    case PR_SockOpt_Keepalive:
+      aData->value.keep_alive = PR_TRUE;
+      break;
+    case PR_SockOpt_NoDelay:
+      aData->value.no_delay = PR_TRUE;
+      break;
+    default:
+      PR_SetError(PR_INVALID_METHOD_ERROR, 0);
+      return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+static PRStatus
+nsNamedPipeSetSocketOption(PRFileDesc* aFd, const PRSocketOptionData* aData)
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  MOZ_ASSERT(aFd);
+  MOZ_ASSERT(aData);
+
+  switch (aData->option) {
+    case PR_SockOpt_Nonblocking:
+      GetNamedPipeInfo(aFd)->SetNonblocking(aData->value.non_blocking);
+      break;
+    case PR_SockOpt_Keepalive:
+    case PR_SockOpt_NoDelay:
+      break;
+    default:
+      PR_SetError(PR_INVALID_METHOD_ERROR, 0);
+      return PR_FAILURE;
+  }
+
+  return PR_SUCCESS;
+}
+
+static void
+Initialize()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  static bool initialized = false;
+  if (initialized) {
+    return;
+  }
+
+  nsNamedPipeLayerIdentity = PR_GetUniqueIdentity("Named Pipe layer");
+  nsNamedPipeLayerMethods = *PR_GetDefaultIOMethods();
+  nsNamedPipeLayerMethods.close = nsNamedPipeClose;
+  nsNamedPipeLayerMethods.read = nsNamedPipeRead;
+  nsNamedPipeLayerMethods.write = nsNamedPipeWrite;
+  nsNamedPipeLayerMethods.available = nsNamedPipeAvailable;
+  nsNamedPipeLayerMethods.available64 = nsNamedPipeAvailable64;
+  nsNamedPipeLayerMethods.fsync = nsNamedPipeSync;
+  nsNamedPipeLayerMethods.connect = nsNamedPipeConnect;
+  nsNamedPipeLayerMethods.recv = nsNamedPipeRecv;
+  nsNamedPipeLayerMethods.send = nsNamedPipeSend;
+  nsNamedPipeLayerMethods.poll = nsNamedPipePoll;
+  nsNamedPipeLayerMethods.getsocketoption = nsNamedPipeGetSocketOption;
+  nsNamedPipeLayerMethods.setsocketoption = nsNamedPipeSetSocketOption;
+  nsNamedPipeLayerMethods.connectcontinue = nsNamedPipeConnectContinue;
+
+  initialized = true;
+}
+
+bool
+IsNamedPipePath(const nsACString& aPath)
+{
+  return StringBeginsWith(aPath, NS_LITERAL_CSTRING("\\\\.\\pipe\\"));
+}
+
+PRFileDesc*
+CreateNamedPipeLayer()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+  Initialize();
+
+  PRFileDesc* layer = PR_CreateIOLayerStub(nsNamedPipeLayerIdentity,
+                                           &nsNamedPipeLayerMethods);
+  if (NS_WARN_IF(!layer)) {
+    LOG_NPIO_ERROR("CreateNamedPipeLayer() failed.");
+    return nullptr;
+  }
+
+  RefPtr<NamedPipeInfo> info = new NamedPipeInfo();
+  layer->secret = reinterpret_cast<PRFilePrivate*>(info.forget().take());
+
+  return layer;
+}
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/socket/nsNamedPipeIOLayer.h b/netwerk/socket/nsNamedPipeIOLayer.h
new file mode 100644
index 000000000..3c5a893d9
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeIOLayer.h
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_netwerk_socket_nsNamedPipeIOLayer_h
+#define mozilla_netwerk_socket_nsNamedPipeIOLayer_h
+
+#include "nscore.h"
+#include "prio.h"
+
+namespace mozilla {
+namespace net {
+
+bool IsNamedPipePath(const nsACString& aPath);
+PRFileDesc* CreateNamedPipeLayer();
+
+extern PRDescIdentity nsNamedPipeLayerIdentity;
+
+} // namespace net
+} // namespace mozilla
+
+#endif // mozilla_netwerk_socket_nsNamedPipeIOLayer_h
diff --git a/netwerk/socket/nsNamedPipeService.cpp b/netwerk/socket/nsNamedPipeService.cpp
new file mode 100644
index 000000000..8e72cc8ef
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeService.cpp
@@ -0,0 +1,324 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Services.h"
+#include "nsCOMPtr.h"
+#include "nsIObserverService.h"
+#include "nsIThread.h"
+#include "nsNamedPipeService.h"
+#include "nsNetCID.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace net {
+
+static mozilla::LazyLogModule gNamedPipeServiceLog("NamedPipeWin");
+#define LOG_NPS_DEBUG(...) \
+  MOZ_LOG(gNamedPipeServiceLog, mozilla::LogLevel::Debug, (__VA_ARGS__))
+#define LOG_NPS_ERROR(...) \
+  MOZ_LOG(gNamedPipeServiceLog, mozilla::LogLevel::Error, (__VA_ARGS__))
+
+NS_IMPL_ISUPPORTS(NamedPipeService,
+                  nsINamedPipeService,
+                  nsIObserver,
+                  nsIRunnable)
+
+NamedPipeService::NamedPipeService()
+  : mIocp(nullptr)
+  , mIsShutdown(false)
+  , mLock("NamedPipeServiceLock")
+{
+}
+
+nsresult
+NamedPipeService::Init()
+{
+  MOZ_ASSERT(!mIsShutdown);
+
+  nsresult rv;
+
+  // nsIObserverService must be accessed in main thread.
+  // register shutdown event to stop NamedPipeSrv thread.
+  nsCOMPtr<nsIObserver> self(this);
+  nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction([self = Move(self)] () -> void {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    nsCOMPtr<nsIObserverService> svc = mozilla::services::GetObserverService();
+
+    if (NS_WARN_IF(!svc)) {
+      return;
+    }
+
+    if (NS_WARN_IF(NS_FAILED(svc->AddObserver(self,
+                                              NS_XPCOM_SHUTDOWN_OBSERVER_ID,
+                                              false)))) {
+      return;
+    }
+  });
+
+  if (NS_IsMainThread()) {
+    rv = r->Run();
+  } else {
+    rv = NS_DispatchToMainThread(r);
+  }
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  mIocp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, nullptr, 0, 1);
+  if (NS_WARN_IF(!mIocp || mIocp == INVALID_HANDLE_VALUE)) {
+    Shutdown();
+    return NS_ERROR_FAILURE;
+  }
+
+  rv = NS_NewNamedThread("NamedPipeSrv", getter_AddRefs(mThread));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    Shutdown();
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+void
+NamedPipeService::Shutdown()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // remove observer
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+  }
+
+  // stop thread
+  if (mThread && !mIsShutdown) {
+    mIsShutdown = true;
+
+    // invoke ERROR_ABANDONED_WAIT_0 to |GetQueuedCompletionStatus|
+    CloseHandle(mIocp);
+    mIocp = nullptr;
+
+    mThread->Shutdown();
+  }
+
+  // close I/O Completion Port
+  if (mIocp && mIocp != INVALID_HANDLE_VALUE) {
+    CloseHandle(mIocp);
+    mIocp = nullptr;
+  }
+}
+
+void
+NamedPipeService::RemoveRetiredObjects()
+{
+  MOZ_ASSERT(NS_GetCurrentThread() == mThread);
+  mLock.AssertCurrentThreadOwns();
+
+  if (!mRetiredHandles.IsEmpty()) {
+    for (auto& handle : mRetiredHandles) {
+      CloseHandle(handle);
+    }
+    mRetiredHandles.Clear();
+  }
+
+  mRetiredObservers.Clear();
+}
+
+/**
+ * Implement nsINamedPipeService
+ */
+
+NS_IMETHODIMP
+NamedPipeService::AddDataObserver(void* aHandle,
+                                  nsINamedPipeDataObserver* aObserver)
+{
+  if (!aHandle || aHandle == INVALID_HANDLE_VALUE || !aObserver) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  nsresult rv;
+
+  HANDLE h = CreateIoCompletionPort(aHandle,
+                                    mIocp,
+                                    reinterpret_cast<ULONG_PTR>(aObserver),
+                                    1);
+  if (NS_WARN_IF(!h)) {
+    LOG_NPS_ERROR("CreateIoCompletionPort error (%d)", GetLastError());
+    return NS_ERROR_FAILURE;
+  }
+  if (NS_WARN_IF(h != mIocp)) {
+    LOG_NPS_ERROR("CreateIoCompletionPort got unexpected value %p (should be %p)",
+              h,
+              mIocp);
+    CloseHandle(h);
+    return NS_ERROR_FAILURE;
+  }
+
+  {
+    MutexAutoLock lock(mLock);
+    MOZ_ASSERT(!mObservers.Contains(aObserver));
+
+    mObservers.AppendElement(aObserver);
+
+    // start event loop
+    if (mObservers.Length() == 1) {
+      rv = mThread->Dispatch(this, NS_DISPATCH_NORMAL);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        LOG_NPS_ERROR("Dispatch to thread failed (%08x)", rv);
+        mObservers.Clear();
+        return rv;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+NamedPipeService::RemoveDataObserver(void* aHandle,
+                                     nsINamedPipeDataObserver* aObserver)
+{
+  MutexAutoLock lock(mLock);
+  mObservers.RemoveElement(aObserver);
+
+  mRetiredHandles.AppendElement(aHandle);
+  mRetiredObservers.AppendElement(aObserver);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+NamedPipeService::IsOnCurrentThread(bool* aRetVal)
+{
+  MOZ_ASSERT(mThread);
+  MOZ_ASSERT(aRetVal);
+
+  if (!mThread) {
+    *aRetVal = false;
+    return NS_OK;
+  }
+
+  return mThread->IsOnCurrentThread(aRetVal);
+}
+
+/**
+ * Implement nsIObserver
+ */
+
+NS_IMETHODIMP
+NamedPipeService::Observe(nsISupports* aSubject,
+                          const char* aTopic,
+                          const char16_t* aData)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!strcmp(NS_XPCOM_SHUTDOWN_OBSERVER_ID, aTopic)) {
+    Shutdown();
+  }
+
+  return NS_OK;
+}
+
+/**
+ * Implement nsIRunnable
+ */
+
+NS_IMETHODIMP
+NamedPipeService::Run()
+{
+  MOZ_ASSERT(NS_GetCurrentThread() == mThread);
+  MOZ_ASSERT(mIocp && mIocp != INVALID_HANDLE_VALUE);
+
+  while (!mIsShutdown) {
+    {
+      MutexAutoLock lock(mLock);
+      if (mObservers.IsEmpty()) {
+        LOG_NPS_DEBUG("no observer, stop loop");
+        break;
+      }
+
+      RemoveRetiredObjects();
+    }
+
+    DWORD bytesTransferred = 0;
+    ULONG_PTR key = 0;
+    LPOVERLAPPED overlapped = nullptr;
+    BOOL success = GetQueuedCompletionStatus(mIocp,
+                                             &bytesTransferred,
+                                             &key,
+                                             &overlapped,
+                                             1000); // timeout, 1s
+    auto err = GetLastError();
+    if (!success) {
+      if (err == WAIT_TIMEOUT) {
+        continue;
+      } else if (err == ERROR_ABANDONED_WAIT_0) { // mIocp was closed
+        break;
+      } else if (!overlapped) {
+        /**
+         * Did not dequeue a completion packet from the completion port, and
+         * bytesTransferred/key are meaningless.
+         * See remarks of |GetQueuedCompletionStatus| API.
+         */
+
+        LOG_NPS_ERROR("invalid overlapped (%d)", err);
+        continue;
+      }
+
+      MOZ_ASSERT(key);
+    }
+
+    /**
+     * Windows doesn't provide a method to remove created I/O Completion Port,
+     * all we can do is just close the handle we monitored before.
+     * In some cases, there's race condition that the monitored handle has an
+     * I/O status after the observer is being removed and destroyed.
+     * To avoid changing the ref-count of a dangling pointer, don't use nsCOMPtr
+     * here.
+     */
+    nsINamedPipeDataObserver* target =
+      reinterpret_cast<nsINamedPipeDataObserver*>(key);
+
+    nsCOMPtr<nsINamedPipeDataObserver> obs;
+    {
+      MutexAutoLock lock(mLock);
+
+      auto idx = mObservers.IndexOf(target);
+      if (idx == decltype(mObservers)::NoIndex) {
+        LOG_NPS_ERROR("observer %p not found", target);
+        continue;
+      }
+      obs = target;
+    }
+
+    MOZ_ASSERT(obs.get());
+
+    if (success) {
+      LOG_NPS_DEBUG("OnDataAvailable: obs=%p, bytes=%d",
+                    obs.get(),
+                    bytesTransferred);
+      obs->OnDataAvailable(bytesTransferred, overlapped);
+    } else {
+      LOG_NPS_ERROR("GetQueuedCompletionStatus %p failed, error=%d",
+                    obs.get(),
+                    err);
+      obs->OnError(err, overlapped);
+    }
+
+  }
+
+  {
+    MutexAutoLock lock(mLock);
+    RemoveRetiredObjects();
+  }
+
+  return NS_OK;
+}
+
+static NS_DEFINE_CID(kNamedPipeServiceCID, NS_NAMEDPIPESERVICE_CID);
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/socket/nsNamedPipeService.h b/netwerk/socket/nsNamedPipeService.h
new file mode 100644
index 000000000..1b4f97cac
--- /dev/null
+++ b/netwerk/socket/nsNamedPipeService.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_netwerk_socket_nsNamedPipeService_h
+#define mozilla_netwerk_socket_nsNamedPipeService_h
+
+#include <windows.h>
+#include "mozilla/Atomics.h"
+#include "mozilla/Mutex.h"
+#include "nsINamedPipeService.h"
+#include "nsIObserver.h"
+#include "nsIRunnable.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace net {
+
+class NamedPipeService final : public nsINamedPipeService
+                             , public nsIObserver
+                             , public nsIRunnable
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSINAMEDPIPESERVICE
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSIRUNNABLE
+
+  explicit NamedPipeService();
+
+  nsresult Init();
+
+private:
+  virtual ~NamedPipeService() = default;
+  void Shutdown();
+  void RemoveRetiredObjects();
+
+  HANDLE mIocp; // native handle to the I/O completion port.
+  Atomic<bool> mIsShutdown; // set to true to stop the event loop running by mThread.
+  nsCOMPtr<nsIThread> mThread; // worker thread to get I/O events.
+
+  /**
+   * The observers is maintained in |mObservers| to ensure valid life-cycle.
+   * We don't remove the handle and corresponding observer directly, instead
+   * the handle and observer into a "retired" list and close/remove them in
+   * the worker thread to avoid a race condition that might happen between
+   * |CloseHandle()| and |GetQueuedCompletionStatus()|.
+   */
+  Mutex mLock;
+  nsTArray<nsCOMPtr<nsINamedPipeDataObserver>> mObservers; // protected by mLock
+  nsTArray<nsCOMPtr<nsINamedPipeDataObserver>> mRetiredObservers; // protected by mLock
+  nsTArray<HANDLE> mRetiredHandles; // protected by mLock
+};
+
+} // namespace net
+} // namespace mozilla
+
+#endif // mozilla_netwerk_socket_nsNamedPipeService_h
diff --git a/netwerk/socket/nsSOCKSIOLayer.cpp b/netwerk/socket/nsSOCKSIOLayer.cpp
new file mode 100644
index 000000000..22f5751fb
--- /dev/null
+++ b/netwerk/socket/nsSOCKSIOLayer.cpp
@@ -0,0 +1,1612 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim:set expandtab ts=4 sw=4 sts=4 cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nspr.h"
+#include "private/pprio.h"
+#include "nsString.h"
+#include "nsCRT.h"
+
+#include "nsIServiceManager.h"
+#include "nsIDNSService.h"
+#include "nsIDNSRecord.h"
+#include "nsISOCKSSocketInfo.h"
+#include "nsISocketProvider.h"
+#include "nsNamedPipeIOLayer.h"
+#include "nsSOCKSIOLayer.h"
+#include "nsNetCID.h"
+#include "nsIDNSListener.h"
+#include "nsICancelable.h"
+#include "nsThreadUtils.h"
+#include "nsIFile.h"
+#include "nsIFileProtocolHandler.h"
+#include "mozilla/Logging.h"
+#include "mozilla/net/DNS.h"
+#include "mozilla/Unused.h"
+
+using mozilla::LogLevel;
+using namespace mozilla::net;
+
+static PRDescIdentity nsSOCKSIOLayerIdentity;
+static PRIOMethods nsSOCKSIOLayerMethods;
+static bool firstTime = true;
+static bool ipv6Supported = true;
+
+
+static mozilla::LazyLogModule gSOCKSLog("SOCKS");
+#define LOGDEBUG(args) MOZ_LOG(gSOCKSLog, mozilla::LogLevel::Debug, args)
+#define LOGERROR(args) MOZ_LOG(gSOCKSLog, mozilla::LogLevel::Error , args)
+
+class nsSOCKSSocketInfo : public nsISOCKSSocketInfo
+                        , public nsIDNSListener
+{
+    enum State {
+        SOCKS_INITIAL,
+        SOCKS_DNS_IN_PROGRESS,
+        SOCKS_DNS_COMPLETE,
+        SOCKS_CONNECTING_TO_PROXY,
+        SOCKS4_WRITE_CONNECT_REQUEST,
+        SOCKS4_READ_CONNECT_RESPONSE,
+        SOCKS5_WRITE_AUTH_REQUEST,
+        SOCKS5_READ_AUTH_RESPONSE,
+        SOCKS5_WRITE_USERNAME_REQUEST,
+        SOCKS5_READ_USERNAME_RESPONSE,
+        SOCKS5_WRITE_CONNECT_REQUEST,
+        SOCKS5_READ_CONNECT_RESPONSE_TOP,
+        SOCKS5_READ_CONNECT_RESPONSE_BOTTOM,
+        SOCKS_CONNECTED,
+        SOCKS_FAILED
+    };
+
+    // A buffer of 520 bytes should be enough for any request and response
+    // in case of SOCKS4 as well as SOCKS5
+    static const uint32_t BUFFER_SIZE = 520;
+    static const uint32_t MAX_HOSTNAME_LEN = 255;
+    static const uint32_t MAX_USERNAME_LEN = 255;
+    static const uint32_t MAX_PASSWORD_LEN = 255;
+
+public:
+    nsSOCKSSocketInfo();
+
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSISOCKSSOCKETINFO
+    NS_DECL_NSIDNSLISTENER
+
+    void Init(int32_t version,
+              int32_t family,
+              nsIProxyInfo *proxy,
+              const char *destinationHost,
+              uint32_t flags);
+
+    void SetConnectTimeout(PRIntervalTime to);
+    PRStatus DoHandshake(PRFileDesc *fd, int16_t oflags = -1);
+    int16_t GetPollFlags() const;
+    bool IsConnected() const { return mState == SOCKS_CONNECTED; }
+    void ForgetFD() { mFD = nullptr; }
+    void SetNamedPipeFD(PRFileDesc *fd) { mFD = fd; }
+
+private:
+    virtual ~nsSOCKSSocketInfo()
+    {
+        ForgetFD();
+        HandshakeFinished();
+    }
+
+    void HandshakeFinished(PRErrorCode err = 0);
+    PRStatus StartDNS(PRFileDesc *fd);
+    PRStatus ConnectToProxy(PRFileDesc *fd);
+    void FixupAddressFamily(PRFileDesc *fd, NetAddr *proxy);
+    PRStatus ContinueConnectingToProxy(PRFileDesc *fd, int16_t oflags);
+    PRStatus WriteV4ConnectRequest();
+    PRStatus ReadV4ConnectResponse();
+    PRStatus WriteV5AuthRequest();
+    PRStatus ReadV5AuthResponse();
+    PRStatus WriteV5UsernameRequest();
+    PRStatus ReadV5UsernameResponse();
+    PRStatus WriteV5ConnectRequest();
+    PRStatus ReadV5AddrTypeAndLength(uint8_t *type, uint32_t *len);
+    PRStatus ReadV5ConnectResponseTop();
+    PRStatus ReadV5ConnectResponseBottom();
+
+    uint8_t ReadUint8();
+    uint16_t ReadUint16();
+    uint32_t ReadUint32();
+    void ReadNetAddr(NetAddr *addr, uint16_t fam);
+    void ReadNetPort(NetAddr *addr);
+
+    void WantRead(uint32_t sz);
+    PRStatus ReadFromSocket(PRFileDesc *fd);
+    PRStatus WriteToSocket(PRFileDesc *fd);
+
+    bool IsLocalProxy()
+    {
+        nsAutoCString proxyHost;
+        mProxy->GetHost(proxyHost);
+        return IsHostLocalTarget(proxyHost);
+    }
+
+    nsresult SetLocalProxyPath(const nsACString& aLocalProxyPath,
+                               NetAddr* aProxyAddr)
+    {
+#ifdef XP_UNIX
+        nsresult rv;
+        MOZ_ASSERT(aProxyAddr);
+
+        nsCOMPtr<nsIProtocolHandler> protocolHandler(
+            do_GetService(NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "file", &rv));
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+        }
+
+        nsCOMPtr<nsIFileProtocolHandler> fileHandler(
+            do_QueryInterface(protocolHandler, &rv));
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+        }
+
+        nsCOMPtr<nsIFile> socketFile;
+        rv = fileHandler->GetFileFromURLSpec(aLocalProxyPath,
+                                             getter_AddRefs(socketFile));
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+        }
+
+        nsAutoCString path;
+        if (NS_WARN_IF(NS_FAILED(rv = socketFile->GetNativePath(path)))) {
+            return rv;
+        }
+
+        if (sizeof(aProxyAddr->local.path) <= path.Length()) {
+            NS_WARNING("domain socket path too long.");
+            return NS_ERROR_FAILURE;
+        }
+
+        aProxyAddr->raw.family = AF_UNIX;
+        strcpy(aProxyAddr->local.path, path.get());
+
+        return NS_OK;
+#elif defined(XP_WIN)
+        MOZ_ASSERT(aProxyAddr);
+
+        if (sizeof(aProxyAddr->local.path) <= aLocalProxyPath.Length()) {
+            NS_WARNING("pipe path too long.");
+            return NS_ERROR_FAILURE;
+        }
+
+        aProxyAddr->raw.family = AF_LOCAL;
+        strcpy(aProxyAddr->local.path, PromiseFlatCString(aLocalProxyPath).get());
+        return NS_OK;
+#else
+        mozilla::Unused << aLocalProxyPath;
+        mozilla::Unused << aProxyAddr;
+        return NS_ERROR_NOT_IMPLEMENTED;
+#endif
+    }
+
+    bool
+    SetupNamedPipeLayer(PRFileDesc *fd)
+    {
+#if defined(XP_WIN)
+        if (IsLocalProxy()) {
+            // nsSOCKSIOLayer handshaking only works under blocking mode
+            // unfortunately. Remember named pipe's FD to switch between modes.
+            SetNamedPipeFD(fd->lower);
+            return true;
+        }
+#endif
+        return false;
+    }
+
+private:
+    State     mState;
+    uint8_t * mData;
+    uint8_t * mDataIoPtr;
+    uint32_t  mDataLength;
+    uint32_t  mReadOffset;
+    uint32_t  mAmountToRead;
+    nsCOMPtr<nsIDNSRecord>  mDnsRec;
+    nsCOMPtr<nsICancelable> mLookup;
+    nsresult                mLookupStatus;
+    PRFileDesc             *mFD;
+
+    nsCString mDestinationHost;
+    nsCOMPtr<nsIProxyInfo> mProxy;
+    int32_t   mVersion;   // SOCKS version 4 or 5
+    int32_t   mDestinationFamily;
+    uint32_t  mFlags;
+    NetAddr   mInternalProxyAddr;
+    NetAddr   mExternalProxyAddr;
+    NetAddr   mDestinationAddr;
+    PRIntervalTime mTimeout;
+    nsCString mProxyUsername; // Cache, from mProxy
+};
+
+nsSOCKSSocketInfo::nsSOCKSSocketInfo()
+    : mState(SOCKS_INITIAL)
+    , mDataIoPtr(nullptr)
+    , mDataLength(0)
+    , mReadOffset(0)
+    , mAmountToRead(0)
+    , mVersion(-1)
+    , mDestinationFamily(AF_INET)
+    , mFlags(0)
+    , mTimeout(PR_INTERVAL_NO_TIMEOUT)
+{
+    mData = new uint8_t[BUFFER_SIZE];
+
+    mInternalProxyAddr.raw.family = AF_INET;
+    mInternalProxyAddr.inet.ip = htonl(INADDR_ANY);
+    mInternalProxyAddr.inet.port = htons(0);
+
+    mExternalProxyAddr.raw.family = AF_INET;
+    mExternalProxyAddr.inet.ip = htonl(INADDR_ANY);
+    mExternalProxyAddr.inet.port = htons(0);
+
+    mDestinationAddr.raw.family = AF_INET;
+    mDestinationAddr.inet.ip = htonl(INADDR_ANY);
+    mDestinationAddr.inet.port = htons(0);
+}
+
+/* Helper template class to statically check that writes to a fixed-size
+ * buffer are not going to overflow.
+ *
+ * Example usage:
+ *   uint8_t real_buf[TOTAL_SIZE];
+ *   Buffer<TOTAL_SIZE> buf(&real_buf);
+ *   auto buf2 = buf.WriteUint16(1);
+ *   auto buf3 = buf2.WriteUint8(2);
+ *
+ * It is possible to chain them, to limit the number of (error-prone)
+ * intermediate variables:
+ *   auto buf = Buffer<TOTAL_SIZE>(&real_buf)
+ *              .WriteUint16(1)
+ *              .WriteUint8(2);
+ *
+ * Debug builds assert when intermediate variables are reused:
+ *   Buffer<TOTAL_SIZE> buf(&real_buf);
+ *   auto buf2 = buf.WriteUint16(1);
+ *   auto buf3 = buf.WriteUint8(2); // Asserts
+ *
+ * Strings can be written, given an explicit maximum length.
+ *   buf.WriteString<MAX_STRING_LENGTH>(str);
+ *
+ * The Written() method returns how many bytes have been written so far:
+ *   Buffer<TOTAL_SIZE> buf(&real_buf);
+ *   auto buf2 = buf.WriteUint16(1);
+ *   auto buf3 = buf2.WriteUint8(2);
+ *   buf3.Written(); // returns 3.
+ */
+template <size_t Size>
+class Buffer
+{
+public:
+  Buffer() : mBuf(nullptr), mLength(0) {}
+
+  explicit Buffer(uint8_t* aBuf, size_t aLength=0)
+  : mBuf(aBuf), mLength(aLength) {}
+
+  template <size_t Size2>
+  MOZ_IMPLICIT Buffer(const Buffer<Size2>& aBuf) : mBuf(aBuf.mBuf), mLength(aBuf.mLength) {
+      static_assert(Size2 > Size, "Cannot cast buffer");
+  }
+
+  Buffer<Size - sizeof(uint8_t)> WriteUint8(uint8_t aValue) {
+      return Write(aValue);
+  }
+
+  Buffer<Size - sizeof(uint16_t)> WriteUint16(uint16_t aValue) {
+      return Write(aValue);
+  }
+
+  Buffer<Size - sizeof(uint32_t)> WriteUint32(uint32_t aValue) {
+      return Write(aValue);
+  }
+
+  Buffer<Size - sizeof(uint16_t)> WriteNetPort(const NetAddr* aAddr) {
+      return WriteUint16(aAddr->inet.port);
+  }
+
+  Buffer<Size - sizeof(IPv6Addr)> WriteNetAddr(const NetAddr* aAddr) {
+      if (aAddr->raw.family == AF_INET) {
+          return Write(aAddr->inet.ip);
+      } else if (aAddr->raw.family == AF_INET6) {
+          return Write(aAddr->inet6.ip.u8);
+      }
+      NS_NOTREACHED("Unknown address family");
+      return *this;
+  }
+
+  template <size_t MaxLength>
+  Buffer<Size - MaxLength> WriteString(const nsACString& aStr) {
+      if (aStr.Length() > MaxLength) {
+          return Buffer<Size - MaxLength>(nullptr);
+      }
+      return WritePtr<char, MaxLength>(aStr.Data(), aStr.Length());
+  }
+
+  size_t Written() {
+      MOZ_ASSERT(mBuf);
+      return mLength;
+  }
+
+  explicit operator bool() { return !!mBuf; }
+private:
+  template <size_t Size2>
+  friend class Buffer;
+
+  template <typename T>
+  Buffer<Size - sizeof(T)> Write(T& aValue) {
+      return WritePtr<T, sizeof(T)>(&aValue, sizeof(T));
+  }
+
+  template <typename T, size_t Length>
+  Buffer<Size - Length> WritePtr(const T* aValue, size_t aCopyLength) {
+      static_assert(Size >= Length, "Cannot write that much");
+      MOZ_ASSERT(aCopyLength <= Length);
+      MOZ_ASSERT(mBuf);
+      memcpy(mBuf, aValue, aCopyLength);
+      Buffer<Size - Length> result(mBuf + aCopyLength, mLength + aCopyLength);
+      mBuf = nullptr;
+      mLength = 0;
+      return result;
+  }
+
+  uint8_t* mBuf;
+  size_t mLength;
+};
+
+
+void
+nsSOCKSSocketInfo::Init(int32_t version, int32_t family, nsIProxyInfo *proxy, const char *host, uint32_t flags)
+{
+    mVersion         = version;
+    mDestinationFamily = family;
+    mProxy           = proxy;
+    mDestinationHost = host;
+    mFlags           = flags;
+    mProxy->GetUsername(mProxyUsername); // cache
+}
+
+NS_IMPL_ISUPPORTS(nsSOCKSSocketInfo, nsISOCKSSocketInfo, nsIDNSListener)
+
+NS_IMETHODIMP 
+nsSOCKSSocketInfo::GetExternalProxyAddr(NetAddr * *aExternalProxyAddr)
+{
+    memcpy(*aExternalProxyAddr, &mExternalProxyAddr, sizeof(NetAddr));
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsSOCKSSocketInfo::SetExternalProxyAddr(NetAddr *aExternalProxyAddr)
+{
+    memcpy(&mExternalProxyAddr, aExternalProxyAddr, sizeof(NetAddr));
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsSOCKSSocketInfo::GetDestinationAddr(NetAddr * *aDestinationAddr)
+{
+    memcpy(*aDestinationAddr, &mDestinationAddr, sizeof(NetAddr));
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsSOCKSSocketInfo::SetDestinationAddr(NetAddr *aDestinationAddr)
+{
+    memcpy(&mDestinationAddr, aDestinationAddr, sizeof(NetAddr));
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsSOCKSSocketInfo::GetInternalProxyAddr(NetAddr * *aInternalProxyAddr)
+{
+    memcpy(*aInternalProxyAddr, &mInternalProxyAddr, sizeof(NetAddr));
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsSOCKSSocketInfo::SetInternalProxyAddr(NetAddr *aInternalProxyAddr)
+{
+    memcpy(&mInternalProxyAddr, aInternalProxyAddr, sizeof(NetAddr));
+    return NS_OK;
+}
+
+// There needs to be a means of distinguishing between connection errors
+// that the SOCKS server reports when it rejects a connection request, and
+// connection errors that happen while attempting to connect to the SOCKS
+// server. Otherwise, Firefox will report incorrectly that the proxy server
+// is refusing connections when a SOCKS request is rejected by the proxy.
+// When a SOCKS handshake failure occurs, the PR error is set to
+// PR_UNKNOWN_ERROR, and the real error code is returned via the OS error.
+void
+nsSOCKSSocketInfo::HandshakeFinished(PRErrorCode err)
+{
+    if (err == 0) {
+        mState = SOCKS_CONNECTED;
+#if defined(XP_WIN)
+        // Switch back to nonblocking mode after finishing handshaking.
+        if (IsLocalProxy() && mFD) {
+            PRSocketOptionData opt_nonblock;
+            opt_nonblock.option = PR_SockOpt_Nonblocking;
+            opt_nonblock.value.non_blocking = PR_TRUE;
+            PR_SetSocketOption(mFD, &opt_nonblock);
+            mFD = nullptr;
+        }
+#endif
+    } else {
+        mState = SOCKS_FAILED;
+        PR_SetError(PR_UNKNOWN_ERROR, err);
+    }
+
+    // We don't need the buffer any longer, so free it.
+    delete [] mData;
+    mData = nullptr;
+    mDataIoPtr = nullptr;
+    mDataLength = 0;
+    mReadOffset = 0;
+    mAmountToRead = 0;
+    if (mLookup) {
+        mLookup->Cancel(NS_ERROR_FAILURE);
+        mLookup = nullptr;
+    }
+}
+
+PRStatus
+nsSOCKSSocketInfo::StartDNS(PRFileDesc *fd)
+{
+    MOZ_ASSERT(!mDnsRec && mState == SOCKS_INITIAL,
+               "Must be in initial state to make DNS Lookup");
+
+    nsCOMPtr<nsIDNSService> dns = do_GetService(NS_DNSSERVICE_CONTRACTID);
+    if (!dns)
+        return PR_FAILURE;
+
+    nsCString proxyHost;
+    mProxy->GetHost(proxyHost);
+
+    mFD  = fd;
+    nsresult rv = dns->AsyncResolve(proxyHost, 0, this,
+                                    NS_GetCurrentThread(),
+                                    getter_AddRefs(mLookup));
+
+    if (NS_FAILED(rv)) {
+        LOGERROR(("socks: DNS lookup for SOCKS proxy %s failed",
+                  proxyHost.get()));
+        return PR_FAILURE;
+    }
+    mState = SOCKS_DNS_IN_PROGRESS;
+    PR_SetError(PR_IN_PROGRESS_ERROR, 0);
+    return PR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsSOCKSSocketInfo::OnLookupComplete(nsICancelable *aRequest,
+                                    nsIDNSRecord *aRecord,
+                                    nsresult aStatus)
+{
+    MOZ_ASSERT(aRequest == mLookup, "wrong DNS query");
+    mLookup = nullptr;
+    mLookupStatus = aStatus;
+    mDnsRec = aRecord;
+    mState = SOCKS_DNS_COMPLETE;
+    if (mFD) {
+      ConnectToProxy(mFD);
+      ForgetFD();
+    }
+    return NS_OK;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ConnectToProxy(PRFileDesc *fd)
+{
+    PRStatus status;
+    nsresult rv;
+
+    MOZ_ASSERT(mState == SOCKS_DNS_COMPLETE,
+               "Must have DNS to make connection!");
+
+    if (NS_FAILED(mLookupStatus)) {
+        PR_SetError(PR_BAD_ADDRESS_ERROR, 0);
+        return PR_FAILURE;
+    }
+
+    // Try socks5 if the destination addrress is IPv6
+    if (mVersion == 4 &&
+        mDestinationAddr.raw.family == AF_INET6) {
+        mVersion = 5;
+    }
+
+    nsAutoCString proxyHost;
+    mProxy->GetHost(proxyHost);
+
+    int32_t proxyPort;
+    mProxy->GetPort(&proxyPort);
+
+    int32_t addresses = 0;
+    do {
+        if (IsLocalProxy()) {
+            rv = SetLocalProxyPath(proxyHost, &mInternalProxyAddr);
+            if (NS_FAILED(rv)) {
+                LOGERROR(("socks: unable to connect to SOCKS proxy, %s",
+                         proxyHost.get()));
+                return PR_FAILURE;
+            }
+        } else {
+            if (addresses++) {
+                mDnsRec->ReportUnusable(proxyPort);
+            }
+
+            rv = mDnsRec->GetNextAddr(proxyPort, &mInternalProxyAddr);
+            // No more addresses to try? If so, we'll need to bail
+            if (NS_FAILED(rv)) {
+                LOGERROR(("socks: unable to connect to SOCKS proxy, %s",
+                         proxyHost.get()));
+                return PR_FAILURE;
+            }
+
+            if (MOZ_LOG_TEST(gSOCKSLog, LogLevel::Debug)) {
+              char buf[kIPv6CStrBufSize];
+              NetAddrToString(&mInternalProxyAddr, buf, sizeof(buf));
+              LOGDEBUG(("socks: trying proxy server, %s:%hu",
+                       buf, ntohs(mInternalProxyAddr.inet.port)));
+            }
+        }
+
+        NetAddr proxy = mInternalProxyAddr;
+        FixupAddressFamily(fd, &proxy);
+        PRNetAddr prProxy;
+        NetAddrToPRNetAddr(&proxy, &prProxy);
+        status = fd->lower->methods->connect(fd->lower, &prProxy, mTimeout);
+        if (status != PR_SUCCESS) {
+            PRErrorCode c = PR_GetError();
+
+            // If EINPROGRESS, return now and check back later after polling
+            if (c == PR_WOULD_BLOCK_ERROR || c == PR_IN_PROGRESS_ERROR) {
+                mState = SOCKS_CONNECTING_TO_PROXY;
+                return status;
+            } else if (IsLocalProxy()) {
+                LOGERROR(("socks: connect to domain socket failed (%d)", c));
+                PR_SetError(PR_CONNECT_REFUSED_ERROR, 0);
+                mState = SOCKS_FAILED;
+                return status;
+            }
+        }
+    } while (status != PR_SUCCESS);
+
+#if defined(XP_WIN)
+    // Switch to blocking mode during handshaking
+    if (IsLocalProxy() && mFD) {
+        PRSocketOptionData opt_nonblock;
+        opt_nonblock.option = PR_SockOpt_Nonblocking;
+        opt_nonblock.value.non_blocking = PR_FALSE;
+        PR_SetSocketOption(mFD, &opt_nonblock);
+    }
+#endif
+
+    // Connected now, start SOCKS
+    if (mVersion == 4)
+        return WriteV4ConnectRequest();
+    return WriteV5AuthRequest();
+}
+
+void
+nsSOCKSSocketInfo::FixupAddressFamily(PRFileDesc *fd, NetAddr *proxy)
+{
+    int32_t proxyFamily = mInternalProxyAddr.raw.family;
+    // Do nothing if the address family is already matched
+    if (proxyFamily == mDestinationFamily) {
+        return;
+    }
+    // If the system does not support IPv6 and the proxy address is IPv6,
+    // We can do nothing here.
+    if (proxyFamily == AF_INET6 && !ipv6Supported) {
+        return;
+    }
+    // If the system does not support IPv6 and the destination address is
+    // IPv6, convert IPv4 address to IPv4-mapped IPv6 address to satisfy
+    // the emulation layer
+    if (mDestinationFamily == AF_INET6 && !ipv6Supported) {
+        proxy->inet6.family = AF_INET6;
+        proxy->inet6.port = mInternalProxyAddr.inet.port;
+        uint8_t *proxyp = proxy->inet6.ip.u8;
+        memset(proxyp, 0, 10);
+        memset(proxyp + 10, 0xff, 2);
+        memcpy(proxyp + 12,(char *) &mInternalProxyAddr.inet.ip, 4);
+        // mDestinationFamily should not be updated
+        return;
+    }
+    // There's no PR_NSPR_IO_LAYER required when using named pipe,
+    // we simply ignore the TCP family here.
+    if (SetupNamedPipeLayer(fd)) {
+        return;
+    }
+
+    // Get an OS native handle from a specified FileDesc
+    PROsfd osfd = PR_FileDesc2NativeHandle(fd);
+    if (osfd == -1) {
+        return;
+    }
+
+    // Create a new FileDesc with a specified family
+    PRFileDesc *tmpfd = PR_OpenTCPSocket(proxyFamily);
+    if (!tmpfd) {
+        return;
+    }
+    PROsfd newsd = PR_FileDesc2NativeHandle(tmpfd);
+    if (newsd == -1) {
+        PR_Close(tmpfd);
+        return;
+    }
+    // Must succeed because PR_FileDesc2NativeHandle succeeded
+    fd = PR_GetIdentitiesLayer(fd, PR_NSPR_IO_LAYER);
+    MOZ_ASSERT(fd);
+    // Swap OS native handles
+    PR_ChangeFileDescNativeHandle(fd, newsd);
+    PR_ChangeFileDescNativeHandle(tmpfd, osfd);
+    // Close temporary FileDesc which is now associated with
+    // old OS native handle
+    PR_Close(tmpfd);
+    mDestinationFamily = proxyFamily;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ContinueConnectingToProxy(PRFileDesc *fd, int16_t oflags)
+{
+    PRStatus status;
+
+    MOZ_ASSERT(mState == SOCKS_CONNECTING_TO_PROXY,
+               "Continuing connection in wrong state!");
+
+    LOGDEBUG(("socks: continuing connection to proxy"));
+
+    status = fd->lower->methods->connectcontinue(fd->lower, oflags);
+    if (status != PR_SUCCESS) {
+        PRErrorCode c = PR_GetError();
+        if (c != PR_WOULD_BLOCK_ERROR && c != PR_IN_PROGRESS_ERROR) {
+            // A connection failure occured, try another address
+            mState = SOCKS_DNS_COMPLETE;
+            return ConnectToProxy(fd);
+        }
+
+        // We're still connecting
+        return PR_FAILURE;
+    }
+
+    // Connected now, start SOCKS
+    if (mVersion == 4)
+        return WriteV4ConnectRequest();
+    return WriteV5AuthRequest();
+}
+
+PRStatus
+nsSOCKSSocketInfo::WriteV4ConnectRequest()
+{
+    if (mProxyUsername.Length() > MAX_USERNAME_LEN) {
+        LOGERROR(("socks username is too long"));
+        HandshakeFinished(PR_UNKNOWN_ERROR);
+        return PR_FAILURE;
+    }
+
+    NetAddr *addr = &mDestinationAddr;
+    int32_t proxy_resolve;
+
+    MOZ_ASSERT(mState == SOCKS_CONNECTING_TO_PROXY,
+               "Invalid state!");
+    
+    proxy_resolve = mFlags & nsISocketProvider::PROXY_RESOLVES_HOST;
+
+    mDataLength = 0;
+    mState = SOCKS4_WRITE_CONNECT_REQUEST;
+
+    LOGDEBUG(("socks4: sending connection request (socks4a resolve? %s)",
+             proxy_resolve? "yes" : "no"));
+
+    // Send a SOCKS 4 connect request.
+    auto buf = Buffer<BUFFER_SIZE>(mData)
+               .WriteUint8(0x04) // version -- 4
+               .WriteUint8(0x01) // command -- connect
+               .WriteNetPort(addr);
+
+    // We don't have anything more to write after the if, so we can
+    // use a buffer with no further writes allowed.
+    Buffer<0> buf3;
+    if (proxy_resolve) {
+        // Add the full name, null-terminated, to the request
+        // according to SOCKS 4a. A fake IP address, with the first
+        // four bytes set to 0 and the last byte set to something other
+        // than 0, is used to notify the proxy that this is a SOCKS 4a
+        // request. This request type works for Tor and perhaps others.
+        // Passwords not supported by V4.
+        auto buf2 = buf.WriteUint32(htonl(0x00000001)) // Fake IP
+                       .WriteString<MAX_USERNAME_LEN>(mProxyUsername)
+                       .WriteUint8(0x00) // Null-terminate username
+                       .WriteString<MAX_HOSTNAME_LEN>(mDestinationHost); // Hostname
+        if (!buf2) {
+            LOGERROR(("socks4: destination host name is too long!"));
+            HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+            return PR_FAILURE;
+        }
+        buf3 = buf2.WriteUint8(0x00);
+    } else if (addr->raw.family == AF_INET) {
+        // Passwords not supported by V4.
+        buf3 = buf.WriteNetAddr(addr) // Add the IPv4 address
+                  .WriteString<MAX_USERNAME_LEN>(mProxyUsername)
+                  .WriteUint8(0x00); // Null-terminate username
+    } else {
+        LOGERROR(("socks: SOCKS 4 can only handle IPv4 addresses!"));
+        HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+        return PR_FAILURE;
+    }
+
+    mDataLength = buf3.Written();
+    return PR_SUCCESS;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadV4ConnectResponse()
+{
+    MOZ_ASSERT(mState == SOCKS4_READ_CONNECT_RESPONSE,
+               "Handling SOCKS 4 connection reply in wrong state!");
+    MOZ_ASSERT(mDataLength == 8,
+               "SOCKS 4 connection reply must be 8 bytes!");
+
+    LOGDEBUG(("socks4: checking connection reply"));
+
+    if (ReadUint8() != 0x00) {
+        LOGERROR(("socks4: wrong connection reply"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+    }
+
+    // See if our connection request was granted
+    if (ReadUint8() == 90) {
+        LOGDEBUG(("socks4: connection successful!"));
+        HandshakeFinished();
+        return PR_SUCCESS;
+    }
+
+    LOGERROR(("socks4: unable to connect"));
+    HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+    return PR_FAILURE;
+}
+
+PRStatus
+nsSOCKSSocketInfo::WriteV5AuthRequest()
+{
+    MOZ_ASSERT(mVersion == 5, "SOCKS version must be 5!");
+
+    mDataLength = 0;
+    mState = SOCKS5_WRITE_AUTH_REQUEST;
+
+    // Send an initial SOCKS 5 greeting
+    LOGDEBUG(("socks5: sending auth methods"));
+    mDataLength = Buffer<BUFFER_SIZE>(mData)
+                  .WriteUint8(0x05) // version -- 5
+                  .WriteUint8(0x01) // # of auth methods -- 1
+                  // Use authenticate iff we have a proxy username.
+                  .WriteUint8(mProxyUsername.IsEmpty() ? 0x00 : 0x02)
+                  .Written();
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadV5AuthResponse()
+{
+    MOZ_ASSERT(mState == SOCKS5_READ_AUTH_RESPONSE,
+               "Handling SOCKS 5 auth method reply in wrong state!");
+    MOZ_ASSERT(mDataLength == 2,
+               "SOCKS 5 auth method reply must be 2 bytes!");
+
+    LOGDEBUG(("socks5: checking auth method reply"));
+
+    // Check version number
+    if (ReadUint8() != 0x05) {
+        LOGERROR(("socks5: unexpected version in the reply"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+    }
+
+    // Make sure our authentication choice was accepted,
+    // and continue accordingly
+    uint8_t authMethod = ReadUint8();
+    if (mProxyUsername.IsEmpty() && authMethod == 0x00) { // no auth
+        LOGDEBUG(("socks5: server allows connection without authentication"));
+        return WriteV5ConnectRequest();
+    } else if (!mProxyUsername.IsEmpty() && authMethod == 0x02) { // username/pw
+        LOGDEBUG(("socks5: auth method accepted by server"));
+        return WriteV5UsernameRequest();
+    } else { // 0xFF signals error
+        LOGERROR(("socks5: server did not accept our authentication method"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+    }
+}
+
+PRStatus
+nsSOCKSSocketInfo::WriteV5UsernameRequest()
+{
+    MOZ_ASSERT(mVersion == 5, "SOCKS version must be 5!");
+
+    if (mProxyUsername.Length() > MAX_USERNAME_LEN) {
+        LOGERROR(("socks username is too long"));
+        HandshakeFinished(PR_UNKNOWN_ERROR);
+        return PR_FAILURE;
+    }
+
+    nsCString password;
+    mProxy->GetPassword(password);
+    if (password.Length() > MAX_PASSWORD_LEN) {
+        LOGERROR(("socks password is too long"));
+        HandshakeFinished(PR_UNKNOWN_ERROR);
+        return PR_FAILURE;
+    }
+
+    mDataLength = 0;
+    mState = SOCKS5_WRITE_USERNAME_REQUEST;
+
+    // RFC 1929 Username/password auth for SOCKS 5
+    LOGDEBUG(("socks5: sending username and password"));
+    mDataLength = Buffer<BUFFER_SIZE>(mData)
+                  .WriteUint8(0x01) // version 1 (not 5)
+                  .WriteUint8(mProxyUsername.Length()) // username length
+                  .WriteString<MAX_USERNAME_LEN>(mProxyUsername) // username
+                  .WriteUint8(password.Length()) // password length
+                  .WriteString<MAX_PASSWORD_LEN>(password) // password. WARNING: Sent unencrypted!
+                  .Written();
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadV5UsernameResponse()
+{
+    MOZ_ASSERT(mState == SOCKS5_READ_USERNAME_RESPONSE,
+                      "Handling SOCKS 5 username/password reply in wrong state!");
+
+    MOZ_ASSERT(mDataLength == 2,
+               "SOCKS 5 username reply must be 2 bytes");
+
+    // Check version number, must be 1 (not 5)
+    if (ReadUint8() != 0x01) {
+        LOGERROR(("socks5: unexpected version in the reply"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+    }
+
+    // Check whether username/password were accepted
+    if (ReadUint8() != 0x00) { // 0 = success
+        LOGERROR(("socks5: username/password not accepted"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+    }
+
+    LOGDEBUG(("socks5: username/password accepted by server"));
+
+    return WriteV5ConnectRequest();
+}
+
+PRStatus
+nsSOCKSSocketInfo::WriteV5ConnectRequest()
+{
+    // Send SOCKS 5 connect request
+    NetAddr *addr = &mDestinationAddr;
+    int32_t proxy_resolve;
+    proxy_resolve = mFlags & nsISocketProvider::PROXY_RESOLVES_HOST;
+
+    LOGDEBUG(("socks5: sending connection request (socks5 resolve? %s)",
+             proxy_resolve? "yes" : "no"));
+
+    mDataLength = 0;
+    mState = SOCKS5_WRITE_CONNECT_REQUEST;
+
+    auto buf = Buffer<BUFFER_SIZE>(mData)
+               .WriteUint8(0x05) // version -- 5
+               .WriteUint8(0x01) // command -- connect
+               .WriteUint8(0x00); // reserved
+   
+    // We're writing a net port after the if, so we need a buffer allowing
+    // to write that much.
+    Buffer<sizeof(uint16_t)> buf2;
+    // Add the address to the SOCKS 5 request. SOCKS 5 supports several
+    // address types, so we pick the one that works best for us.
+    if (proxy_resolve) {
+        // Add the host name. Only a single byte is used to store the length,
+        // so we must prevent long names from being used.
+        buf2 = buf.WriteUint8(0x03) // addr type -- domainname
+                  .WriteUint8(mDestinationHost.Length()) // name length
+                  .WriteString<MAX_HOSTNAME_LEN>(mDestinationHost); // Hostname
+        if (!buf2) {
+            LOGERROR(("socks5: destination host name is too long!"));
+            HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+            return PR_FAILURE;
+        }
+    } else if (addr->raw.family == AF_INET) {
+        buf2 = buf.WriteUint8(0x01) // addr type -- IPv4
+                  .WriteNetAddr(addr);
+    } else if (addr->raw.family == AF_INET6) {
+        buf2 = buf.WriteUint8(0x04) // addr type -- IPv6
+                  .WriteNetAddr(addr);
+    } else {
+        LOGERROR(("socks5: destination address of unknown type!"));
+        HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+        return PR_FAILURE;
+    }
+
+    auto buf3 = buf2.WriteNetPort(addr); // port
+    mDataLength = buf3.Written();
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadV5AddrTypeAndLength(uint8_t *type, uint32_t *len)
+{
+    MOZ_ASSERT(mState == SOCKS5_READ_CONNECT_RESPONSE_TOP ||
+               mState == SOCKS5_READ_CONNECT_RESPONSE_BOTTOM,
+               "Invalid state!");
+    MOZ_ASSERT(mDataLength >= 5,
+               "SOCKS 5 connection reply must be at least 5 bytes!");
+ 
+    // Seek to the address location 
+    mReadOffset = 3;
+   
+    *type = ReadUint8();
+
+    switch (*type) {
+        case 0x01: // ipv4
+            *len = 4 - 1;
+            break;
+        case 0x04: // ipv6
+            *len = 16 - 1;
+            break;
+        case 0x03: // fqdn
+            *len = ReadUint8();
+            break;
+        default:   // wrong address type
+            LOGERROR(("socks5: wrong address type in connection reply!"));
+            return PR_FAILURE;
+    }
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadV5ConnectResponseTop()
+{
+    uint8_t res;
+    uint32_t len;
+
+    MOZ_ASSERT(mState == SOCKS5_READ_CONNECT_RESPONSE_TOP,
+               "Invalid state!");
+    MOZ_ASSERT(mDataLength == 5,
+               "SOCKS 5 connection reply must be exactly 5 bytes!");
+
+    LOGDEBUG(("socks5: checking connection reply"));
+
+    // Check version number
+    if (ReadUint8() != 0x05) {
+        LOGERROR(("socks5: unexpected version in the reply"));
+        HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+        return PR_FAILURE;
+    }
+
+    // Check response
+    res = ReadUint8();
+    if (res != 0x00) {
+        PRErrorCode c = PR_CONNECT_REFUSED_ERROR;
+
+        switch (res) {
+            case 0x01:
+                LOGERROR(("socks5: connect failed: "
+                          "01, General SOCKS server failure."));
+                break;
+            case 0x02:
+                LOGERROR(("socks5: connect failed: "
+                          "02, Connection not allowed by ruleset."));
+                break;
+            case 0x03:
+                LOGERROR(("socks5: connect failed: 03, Network unreachable."));
+                c = PR_NETWORK_UNREACHABLE_ERROR;
+                break;
+            case 0x04:
+                LOGERROR(("socks5: connect failed: 04, Host unreachable."));
+                break;
+            case 0x05:
+                LOGERROR(("socks5: connect failed: 05, Connection refused."));
+                break;
+            case 0x06:  
+                LOGERROR(("socks5: connect failed: 06, TTL expired."));
+                c = PR_CONNECT_TIMEOUT_ERROR;
+                break;
+            case 0x07:
+                LOGERROR(("socks5: connect failed: "
+                          "07, Command not supported."));
+                break;
+            case 0x08:
+                LOGERROR(("socks5: connect failed: "
+                          "08, Address type not supported."));
+                c = PR_BAD_ADDRESS_ERROR;
+                break;
+            default:
+                LOGERROR(("socks5: connect failed."));
+                break;
+        }
+
+        HandshakeFinished(c);
+        return PR_FAILURE;
+    }
+
+    if (ReadV5AddrTypeAndLength(&res, &len) != PR_SUCCESS) {
+        HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+        return PR_FAILURE;
+    }
+
+    mState = SOCKS5_READ_CONNECT_RESPONSE_BOTTOM;
+    WantRead(len + 2);
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadV5ConnectResponseBottom()
+{
+    uint8_t type;
+    uint32_t len;
+
+    MOZ_ASSERT(mState == SOCKS5_READ_CONNECT_RESPONSE_BOTTOM,
+               "Invalid state!");
+
+    if (ReadV5AddrTypeAndLength(&type, &len) != PR_SUCCESS) {
+        HandshakeFinished(PR_BAD_ADDRESS_ERROR);
+        return PR_FAILURE;
+    }
+
+    MOZ_ASSERT(mDataLength == 7+len,
+               "SOCKS 5 unexpected length of connection reply!");
+
+    LOGDEBUG(("socks5: loading source addr and port"));
+    // Read what the proxy says is our source address
+    switch (type) {
+        case 0x01: // ipv4
+            ReadNetAddr(&mExternalProxyAddr, AF_INET);
+            break;
+        case 0x04: // ipv6
+            ReadNetAddr(&mExternalProxyAddr, AF_INET6);
+            break;
+        case 0x03: // fqdn (skip)
+            mReadOffset += len;
+            mExternalProxyAddr.raw.family = AF_INET;
+            break;
+    }
+
+    ReadNetPort(&mExternalProxyAddr);
+
+    LOGDEBUG(("socks5: connected!"));
+    HandshakeFinished();
+
+    return PR_SUCCESS;
+}
+
+void
+nsSOCKSSocketInfo::SetConnectTimeout(PRIntervalTime to)
+{
+    mTimeout = to;
+}
+
+PRStatus
+nsSOCKSSocketInfo::DoHandshake(PRFileDesc *fd, int16_t oflags)
+{
+    LOGDEBUG(("socks: DoHandshake(), state = %d", mState));
+
+    switch (mState) {
+        case SOCKS_INITIAL:
+            if (IsLocalProxy()) {
+                mState = SOCKS_DNS_COMPLETE;
+                mLookupStatus = NS_OK;
+                return ConnectToProxy(fd);
+            }
+
+            return StartDNS(fd);
+        case SOCKS_DNS_IN_PROGRESS:
+            PR_SetError(PR_IN_PROGRESS_ERROR, 0);
+            return PR_FAILURE;
+        case SOCKS_DNS_COMPLETE:
+            return ConnectToProxy(fd);
+        case SOCKS_CONNECTING_TO_PROXY:
+            return ContinueConnectingToProxy(fd, oflags);
+        case SOCKS4_WRITE_CONNECT_REQUEST:
+            if (WriteToSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            WantRead(8);
+            mState = SOCKS4_READ_CONNECT_RESPONSE;
+            return PR_SUCCESS;
+        case SOCKS4_READ_CONNECT_RESPONSE:
+            if (ReadFromSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            return ReadV4ConnectResponse();
+
+        case SOCKS5_WRITE_AUTH_REQUEST:
+            if (WriteToSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            WantRead(2);
+            mState = SOCKS5_READ_AUTH_RESPONSE;
+            return PR_SUCCESS;
+        case SOCKS5_READ_AUTH_RESPONSE:
+            if (ReadFromSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            return ReadV5AuthResponse();
+        case SOCKS5_WRITE_USERNAME_REQUEST:
+            if (WriteToSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            WantRead(2);
+            mState = SOCKS5_READ_USERNAME_RESPONSE;
+            return PR_SUCCESS;
+        case SOCKS5_READ_USERNAME_RESPONSE:
+            if (ReadFromSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            return ReadV5UsernameResponse();
+        case SOCKS5_WRITE_CONNECT_REQUEST:
+            if (WriteToSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+
+            // The SOCKS 5 response to the connection request is variable
+            // length. First, we'll read enough to tell how long the response
+            // is, and will read the rest later.
+            WantRead(5);
+            mState = SOCKS5_READ_CONNECT_RESPONSE_TOP;
+            return PR_SUCCESS;
+        case SOCKS5_READ_CONNECT_RESPONSE_TOP:
+            if (ReadFromSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            return ReadV5ConnectResponseTop();
+        case SOCKS5_READ_CONNECT_RESPONSE_BOTTOM:
+            if (ReadFromSocket(fd) != PR_SUCCESS)
+                return PR_FAILURE;
+            return ReadV5ConnectResponseBottom();
+
+        case SOCKS_CONNECTED:
+            LOGERROR(("socks: already connected"));
+            HandshakeFinished(PR_IS_CONNECTED_ERROR);
+            return PR_FAILURE;
+        case SOCKS_FAILED:
+            LOGERROR(("socks: already failed"));
+            return PR_FAILURE;
+    }
+
+    LOGERROR(("socks: executing handshake in invalid state, %d", mState));
+    HandshakeFinished(PR_INVALID_STATE_ERROR);
+
+    return PR_FAILURE;
+}
+
+int16_t
+nsSOCKSSocketInfo::GetPollFlags() const
+{
+    switch (mState) {
+        case SOCKS_DNS_IN_PROGRESS:
+        case SOCKS_DNS_COMPLETE:
+        case SOCKS_CONNECTING_TO_PROXY:
+            return PR_POLL_EXCEPT | PR_POLL_WRITE;
+        case SOCKS4_WRITE_CONNECT_REQUEST:
+        case SOCKS5_WRITE_AUTH_REQUEST:
+        case SOCKS5_WRITE_USERNAME_REQUEST:
+        case SOCKS5_WRITE_CONNECT_REQUEST:
+            return PR_POLL_WRITE;
+        case SOCKS4_READ_CONNECT_RESPONSE:
+        case SOCKS5_READ_AUTH_RESPONSE:
+        case SOCKS5_READ_USERNAME_RESPONSE:
+        case SOCKS5_READ_CONNECT_RESPONSE_TOP:
+        case SOCKS5_READ_CONNECT_RESPONSE_BOTTOM:
+            return PR_POLL_READ;
+        default:
+            break;
+    }
+
+    return 0;
+}
+
+inline uint8_t
+nsSOCKSSocketInfo::ReadUint8()
+{
+    uint8_t rv;
+    MOZ_ASSERT(mReadOffset + sizeof(rv) <= mDataLength,
+               "Not enough space to pop a uint8_t!");
+    rv = mData[mReadOffset];
+    mReadOffset += sizeof(rv);
+    return rv;
+}
+
+inline uint16_t
+nsSOCKSSocketInfo::ReadUint16()
+{
+    uint16_t rv;
+    MOZ_ASSERT(mReadOffset + sizeof(rv) <= mDataLength,
+               "Not enough space to pop a uint16_t!");
+    memcpy(&rv, mData + mReadOffset, sizeof(rv));
+    mReadOffset += sizeof(rv);
+    return rv;
+}
+
+inline uint32_t
+nsSOCKSSocketInfo::ReadUint32()
+{
+    uint32_t rv;
+    MOZ_ASSERT(mReadOffset + sizeof(rv) <= mDataLength,
+               "Not enough space to pop a uint32_t!");
+    memcpy(&rv, mData + mReadOffset, sizeof(rv));
+    mReadOffset += sizeof(rv);
+    return rv;
+}
+
+void
+nsSOCKSSocketInfo::ReadNetAddr(NetAddr *addr, uint16_t fam)
+{
+    uint32_t amt = 0;
+    const uint8_t *ip = mData + mReadOffset;
+
+    addr->raw.family = fam;
+    if (fam == AF_INET) {
+        amt = sizeof(addr->inet.ip);
+        MOZ_ASSERT(mReadOffset + amt <= mDataLength,
+                   "Not enough space to pop an ipv4 addr!");
+        memcpy(&addr->inet.ip, ip, amt);
+    } else if (fam == AF_INET6) {
+        amt = sizeof(addr->inet6.ip.u8);
+        MOZ_ASSERT(mReadOffset + amt <= mDataLength,
+                   "Not enough space to pop an ipv6 addr!");
+        memcpy(addr->inet6.ip.u8, ip, amt);
+    }
+
+    mReadOffset += amt;
+}
+
+void
+nsSOCKSSocketInfo::ReadNetPort(NetAddr *addr)
+{
+    addr->inet.port = ReadUint16();
+}
+
+void
+nsSOCKSSocketInfo::WantRead(uint32_t sz)
+{
+    MOZ_ASSERT(mDataIoPtr == nullptr,
+               "WantRead() called while I/O already in progress!");
+    MOZ_ASSERT(mDataLength + sz <= BUFFER_SIZE,
+               "Can't read that much data!");
+    mAmountToRead = sz;
+}
+
+PRStatus
+nsSOCKSSocketInfo::ReadFromSocket(PRFileDesc *fd)
+{
+    int32_t rc;
+    const uint8_t *end;
+
+    if (!mAmountToRead) {
+        LOGDEBUG(("socks: ReadFromSocket(), nothing to do"));
+        return PR_SUCCESS;
+    }
+
+    if (!mDataIoPtr) {
+        mDataIoPtr = mData + mDataLength;
+        mDataLength += mAmountToRead;
+    }
+
+    end = mData + mDataLength;
+
+    while (mDataIoPtr < end) {
+        rc = PR_Read(fd, mDataIoPtr, end - mDataIoPtr);
+        if (rc <= 0) {
+            if (rc == 0) {
+                LOGERROR(("socks: proxy server closed connection"));
+                HandshakeFinished(PR_CONNECT_REFUSED_ERROR);
+                return PR_FAILURE;
+            } else if (PR_GetError() == PR_WOULD_BLOCK_ERROR) {
+                LOGDEBUG(("socks: ReadFromSocket(), want read"));
+            }
+            break;
+        }
+
+        mDataIoPtr += rc;
+    }
+
+    LOGDEBUG(("socks: ReadFromSocket(), have %u bytes total",
+             unsigned(mDataIoPtr - mData)));
+    if (mDataIoPtr == end) {
+        mDataIoPtr = nullptr;
+        mAmountToRead = 0;
+        mReadOffset = 0;
+        return PR_SUCCESS;
+    }
+
+    return PR_FAILURE;
+}
+
+PRStatus
+nsSOCKSSocketInfo::WriteToSocket(PRFileDesc *fd)
+{
+    int32_t rc;
+    const uint8_t *end;
+
+    if (!mDataLength) {
+        LOGDEBUG(("socks: WriteToSocket(), nothing to do"));
+        return PR_SUCCESS;
+    }
+
+    if (!mDataIoPtr)
+        mDataIoPtr = mData;
+
+    end = mData + mDataLength;
+
+    while (mDataIoPtr < end) {
+        rc = PR_Write(fd, mDataIoPtr, end - mDataIoPtr);
+        if (rc < 0) {
+            if (PR_GetError() == PR_WOULD_BLOCK_ERROR) {
+                LOGDEBUG(("socks: WriteToSocket(), want write"));
+            }
+            break;
+        }
+        
+        mDataIoPtr += rc;
+    }
+
+    if (mDataIoPtr == end) {
+        mDataIoPtr = nullptr;
+        mDataLength = 0;
+        mReadOffset = 0;
+        return PR_SUCCESS;
+    }
+    
+    return PR_FAILURE;
+}
+
+static PRStatus
+nsSOCKSIOLayerConnect(PRFileDesc *fd, const PRNetAddr *addr, PRIntervalTime to)
+{
+    PRStatus status;
+    NetAddr dst;
+
+    nsSOCKSSocketInfo * info = (nsSOCKSSocketInfo*) fd->secret;
+    if (info == nullptr) return PR_FAILURE;
+
+    if (addr->raw.family == PR_AF_INET6 &&
+        PR_IsNetAddrType(addr, PR_IpAddrV4Mapped)) {
+        const uint8_t *srcp;
+
+        LOGDEBUG(("socks: converting ipv4-mapped ipv6 address to ipv4"));
+
+        // copied from _PR_ConvertToIpv4NetAddr()
+        dst.raw.family = AF_INET;
+        dst.inet.ip = htonl(INADDR_ANY);
+        dst.inet.port = htons(0);
+        srcp = addr->ipv6.ip.pr_s6_addr;
+        memcpy(&dst.inet.ip, srcp + 12, 4);
+        dst.inet.family = AF_INET;
+        dst.inet.port = addr->ipv6.port;
+    } else {
+        memcpy(&dst, addr, sizeof(dst));
+    }
+
+    info->SetDestinationAddr(&dst);
+    info->SetConnectTimeout(to);
+
+    do {
+        status = info->DoHandshake(fd, -1);
+    } while (status == PR_SUCCESS && !info->IsConnected());
+
+    return status;
+}
+
+static PRStatus
+nsSOCKSIOLayerConnectContinue(PRFileDesc *fd, int16_t oflags)
+{
+    PRStatus status;
+
+    nsSOCKSSocketInfo * info = (nsSOCKSSocketInfo*) fd->secret;
+    if (info == nullptr) return PR_FAILURE;
+
+    do { 
+        status = info->DoHandshake(fd, oflags);
+    } while (status == PR_SUCCESS && !info->IsConnected());
+
+    return status;
+}
+
+static int16_t
+nsSOCKSIOLayerPoll(PRFileDesc *fd, int16_t in_flags, int16_t *out_flags)
+{
+    nsSOCKSSocketInfo * info = (nsSOCKSSocketInfo*) fd->secret;
+    if (info == nullptr) return PR_FAILURE;
+
+    if (!info->IsConnected()) {
+        *out_flags = 0;
+        return info->GetPollFlags();
+    }
+
+    return fd->lower->methods->poll(fd->lower, in_flags, out_flags);
+}
+
+static PRStatus
+nsSOCKSIOLayerClose(PRFileDesc *fd)
+{
+    nsSOCKSSocketInfo * info = (nsSOCKSSocketInfo*) fd->secret;
+    PRDescIdentity id = PR_GetLayersIdentity(fd);
+
+    if (info && id == nsSOCKSIOLayerIdentity)
+    {
+        info->ForgetFD();
+        NS_RELEASE(info);
+        fd->identity = PR_INVALID_IO_LAYER;
+    }
+
+    return fd->lower->methods->close(fd->lower);
+}
+
+static PRFileDesc*
+nsSOCKSIOLayerAccept(PRFileDesc *fd, PRNetAddr *addr, PRIntervalTime timeout)
+{
+    // TODO: implement SOCKS support for accept
+    return fd->lower->methods->accept(fd->lower, addr, timeout);
+}
+
+static int32_t
+nsSOCKSIOLayerAcceptRead(PRFileDesc *sd, PRFileDesc **nd, PRNetAddr **raddr, void *buf, int32_t amount, PRIntervalTime timeout)
+{
+    // TODO: implement SOCKS support for accept, then read from it
+    return sd->lower->methods->acceptread(sd->lower, nd, raddr, buf, amount, timeout);
+}
+
+static PRStatus
+nsSOCKSIOLayerBind(PRFileDesc *fd, const PRNetAddr *addr)
+{
+    // TODO: implement SOCKS support for bind (very similar to connect)
+    return fd->lower->methods->bind(fd->lower, addr);
+}
+
+static PRStatus
+nsSOCKSIOLayerGetName(PRFileDesc *fd, PRNetAddr *addr)
+{
+    nsSOCKSSocketInfo * info = (nsSOCKSSocketInfo*) fd->secret;
+    
+    if (info != nullptr && addr != nullptr) {
+        NetAddr temp;
+        NetAddr *tempPtr = &temp;
+        if (info->GetExternalProxyAddr(&tempPtr) == NS_OK) {
+            NetAddrToPRNetAddr(tempPtr, addr);
+            return PR_SUCCESS;
+        }
+    }
+
+    return PR_FAILURE;
+}
+
+static PRStatus
+nsSOCKSIOLayerGetPeerName(PRFileDesc *fd, PRNetAddr *addr)
+{
+    nsSOCKSSocketInfo * info = (nsSOCKSSocketInfo*) fd->secret;
+
+    if (info != nullptr && addr != nullptr) {
+        NetAddr temp;
+        NetAddr *tempPtr = &temp;
+        if (info->GetDestinationAddr(&tempPtr) == NS_OK) {
+            NetAddrToPRNetAddr(tempPtr, addr);
+            return PR_SUCCESS;
+        }
+    }
+
+    return PR_FAILURE;
+}
+
+static PRStatus
+nsSOCKSIOLayerListen(PRFileDesc *fd, int backlog)
+{
+    // TODO: implement SOCKS support for listen
+    return fd->lower->methods->listen(fd->lower, backlog);
+}
+
+// add SOCKS IO layer to an existing socket
+nsresult
+nsSOCKSIOLayerAddToSocket(int32_t family,
+                          const char *host, 
+                          int32_t port,
+                          nsIProxyInfo *proxy,
+                          int32_t socksVersion,
+                          uint32_t flags,
+                          PRFileDesc *fd, 
+                          nsISupports** info)
+{
+    NS_ENSURE_TRUE((socksVersion == 4) || (socksVersion == 5), NS_ERROR_NOT_INITIALIZED);
+
+
+    if (firstTime)
+    {
+        //XXX hack until NSPR provides an official way to detect system IPv6
+        // support (bug 388519)
+        PRFileDesc *tmpfd = PR_OpenTCPSocket(PR_AF_INET6);
+        if (!tmpfd) {
+            ipv6Supported = false;
+        } else {
+            // If the system does not support IPv6, NSPR will push
+            // IPv6-to-IPv4 emulation layer onto the native layer
+            ipv6Supported = PR_GetIdentitiesLayer(tmpfd, PR_NSPR_IO_LAYER) == tmpfd;
+            PR_Close(tmpfd);
+        }
+
+        nsSOCKSIOLayerIdentity = PR_GetUniqueIdentity("SOCKS layer");
+        nsSOCKSIOLayerMethods = *PR_GetDefaultIOMethods();
+
+        nsSOCKSIOLayerMethods.connect = nsSOCKSIOLayerConnect;
+        nsSOCKSIOLayerMethods.connectcontinue = nsSOCKSIOLayerConnectContinue;
+        nsSOCKSIOLayerMethods.poll = nsSOCKSIOLayerPoll;
+        nsSOCKSIOLayerMethods.bind = nsSOCKSIOLayerBind;
+        nsSOCKSIOLayerMethods.acceptread = nsSOCKSIOLayerAcceptRead;
+        nsSOCKSIOLayerMethods.getsockname = nsSOCKSIOLayerGetName;
+        nsSOCKSIOLayerMethods.getpeername = nsSOCKSIOLayerGetPeerName;
+        nsSOCKSIOLayerMethods.accept = nsSOCKSIOLayerAccept;
+        nsSOCKSIOLayerMethods.listen = nsSOCKSIOLayerListen;
+        nsSOCKSIOLayerMethods.close = nsSOCKSIOLayerClose;
+
+        firstTime = false;
+    }
+
+    LOGDEBUG(("Entering nsSOCKSIOLayerAddToSocket()."));
+
+    PRFileDesc *layer;
+    PRStatus rv;
+
+    layer = PR_CreateIOLayerStub(nsSOCKSIOLayerIdentity, &nsSOCKSIOLayerMethods);
+    if (! layer)
+    {
+        LOGERROR(("PR_CreateIOLayerStub() failed."));
+        return NS_ERROR_FAILURE;
+    }
+
+    nsSOCKSSocketInfo * infoObject = new nsSOCKSSocketInfo();
+    if (!infoObject)
+    {
+        // clean up IOLayerStub
+        LOGERROR(("Failed to create nsSOCKSSocketInfo()."));
+        PR_DELETE(layer);
+        return NS_ERROR_FAILURE;
+    }
+
+    NS_ADDREF(infoObject);
+    infoObject->Init(socksVersion, family, proxy, host, flags);
+    layer->secret = (PRFilePrivate*) infoObject;
+
+    PRDescIdentity fdIdentity = PR_GetLayersIdentity(fd);
+#if defined(XP_WIN)
+    if (fdIdentity == mozilla::net::nsNamedPipeLayerIdentity) {
+        // remember named pipe fd on the info object so that we can switch
+        // blocking and non-blocking mode on the pipe later.
+        infoObject->SetNamedPipeFD(fd);
+    }
+#endif
+    rv = PR_PushIOLayer(fd, fdIdentity, layer);
+
+    if (rv == PR_FAILURE) {
+        LOGERROR(("PR_PushIOLayer() failed. rv = %x.", rv));
+        NS_RELEASE(infoObject);
+        PR_DELETE(layer);
+        return NS_ERROR_FAILURE;
+    }
+
+    *info = static_cast<nsISOCKSSocketInfo*>(infoObject);
+    NS_ADDREF(*info);
+    return NS_OK;
+}
+
+bool
+IsHostLocalTarget(const nsACString& aHost)
+{
+#if defined(XP_UNIX)
+    return StringBeginsWith(aHost, NS_LITERAL_CSTRING("file:"));
+#elif defined(XP_WIN)
+    return IsNamedPipePath(aHost);
+#else
+    return false;
+#endif // XP_UNIX
+}
diff --git a/netwerk/socket/nsSOCKSIOLayer.h b/netwerk/socket/nsSOCKSIOLayer.h
new file mode 100644
index 000000000..afbbc3606
--- /dev/null
+++ b/netwerk/socket/nsSOCKSIOLayer.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSOCKSIOLayer_h__
+#define nsSOCKSIOLayer_h__
+
+#include "prio.h"
+#include "nscore.h"
+#include "nsIProxyInfo.h"
+
+nsresult nsSOCKSIOLayerAddToSocket(int32_t       family,
+                                   const char   *host, 
+                                   int32_t       port,
+                                   nsIProxyInfo *proxyInfo,
+                                   int32_t       socksVersion,
+                                   uint32_t      flags,
+                                   PRFileDesc   *fd, 
+                                   nsISupports **info);
+
+bool IsHostLocalTarget(const nsACString& aHost);
+
+#endif /* nsSOCKSIOLayer_h__ */
diff --git a/netwerk/socket/nsSOCKSSocketProvider.cpp b/netwerk/socket/nsSOCKSSocketProvider.cpp
new file mode 100644
index 000000000..c62534f7b
--- /dev/null
+++ b/netwerk/socket/nsSOCKSSocketProvider.cpp
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIServiceManager.h"
+#include "nsNamedPipeIOLayer.h"
+#include "nsSOCKSSocketProvider.h"
+#include "nsSOCKSIOLayer.h"
+#include "nsCOMPtr.h"
+#include "nsError.h"
+
+using mozilla::NeckoOriginAttributes;
+
+//////////////////////////////////////////////////////////////////////////
+
+NS_IMPL_ISUPPORTS(nsSOCKSSocketProvider, nsISocketProvider)
+
+nsresult
+nsSOCKSSocketProvider::CreateV4(nsISupports *aOuter, REFNSIID aIID, void **aResult)
+{
+    nsresult rv;
+    nsCOMPtr<nsISocketProvider> inst =
+            new nsSOCKSSocketProvider(NS_SOCKS_VERSION_4);
+    if (!inst)
+        rv = NS_ERROR_OUT_OF_MEMORY;
+    else
+        rv = inst->QueryInterface(aIID, aResult); 
+    return rv;
+}
+
+nsresult
+nsSOCKSSocketProvider::CreateV5(nsISupports *aOuter, REFNSIID aIID, void **aResult)
+{
+    nsresult rv;
+    nsCOMPtr<nsISocketProvider> inst =
+            new nsSOCKSSocketProvider(NS_SOCKS_VERSION_5);
+    if (!inst)
+        rv = NS_ERROR_OUT_OF_MEMORY;
+    else
+        rv = inst->QueryInterface(aIID, aResult); 
+    return rv;
+}
+
+NS_IMETHODIMP
+nsSOCKSSocketProvider::NewSocket(int32_t family,
+                                 const char *host, 
+                                 int32_t port,
+                                 nsIProxyInfo *proxy,
+                                 const NeckoOriginAttributes &originAttributes,
+                                 uint32_t flags,
+                                 PRFileDesc **result,
+                                 nsISupports **socksInfo)
+{
+    PRFileDesc *sock;
+
+#if defined(XP_WIN)
+    nsAutoCString proxyHost;
+    proxy->GetHost(proxyHost);
+    if (IsNamedPipePath(proxyHost)) {
+        sock = CreateNamedPipeLayer();
+    } else
+#endif
+    {
+        sock = PR_OpenTCPSocket(family);
+        if (!sock) {
+            return NS_ERROR_OUT_OF_MEMORY;
+        }
+    }
+
+    nsresult rv = nsSOCKSIOLayerAddToSocket(family,
+                                            host, 
+                                            port,
+                                            proxy,
+                                            mVersion,
+                                            flags,
+                                            sock, 
+                                            socksInfo);
+    if (NS_SUCCEEDED(rv)) {
+        *result = sock;
+        return NS_OK;
+    }
+
+    return NS_ERROR_SOCKET_CREATE_FAILED;
+}
+
+NS_IMETHODIMP
+nsSOCKSSocketProvider::AddToSocket(int32_t family,
+                                   const char *host,
+                                   int32_t port,
+                                   nsIProxyInfo *proxy,
+                                   const NeckoOriginAttributes &originAttributes,
+                                   uint32_t flags,
+                                   PRFileDesc *sock,
+                                   nsISupports **socksInfo)
+{
+    nsresult rv = nsSOCKSIOLayerAddToSocket(family,
+                                            host, 
+                                            port,
+                                            proxy,
+                                            mVersion,
+                                            flags,
+                                            sock, 
+                                            socksInfo);
+    
+    if (NS_FAILED(rv))
+        rv = NS_ERROR_SOCKET_CREATE_FAILED;
+    return rv;
+}
diff --git a/netwerk/socket/nsSOCKSSocketProvider.h b/netwerk/socket/nsSOCKSSocketProvider.h
new file mode 100644
index 000000000..d468ec36e
--- /dev/null
+++ b/netwerk/socket/nsSOCKSSocketProvider.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSOCKSSocketProvider_h__
+#define nsSOCKSSocketProvider_h__
+
+#include "nsISocketProvider.h"
+
+// values for ctor's |version| argument
+enum {
+    NS_SOCKS_VERSION_4 = 4,
+    NS_SOCKS_VERSION_5 = 5
+};
+
+class nsSOCKSSocketProvider : public nsISocketProvider
+{
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSISOCKETPROVIDER
+
+    explicit nsSOCKSSocketProvider(uint32_t version) : mVersion(version) {}
+
+    static nsresult CreateV4(nsISupports *, REFNSIID aIID, void **aResult);
+    static nsresult CreateV5(nsISupports *, REFNSIID aIID, void **aResult);
+
+private:
+    virtual ~nsSOCKSSocketProvider() {}
+
+    uint32_t mVersion; // NS_SOCKS_VERSION_4 or 5
+};
+
+#endif /* nsSOCKSSocketProvider_h__ */
diff --git a/netwerk/socket/nsSocketProviderService.cpp b/netwerk/socket/nsSocketProviderService.cpp
new file mode 100644
index 000000000..b3fc5d9e7
--- /dev/null
+++ b/netwerk/socket/nsSocketProviderService.cpp
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsString.h"
+#include "nsIServiceManager.h"
+#include "nsISocketProvider.h"
+#include "nsSocketProviderService.h"
+#include "nsError.h"
+
+////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+nsSocketProviderService::Create(nsISupports *aOuter, REFNSIID aIID, void **aResult)
+{
+  nsresult rv;
+  nsCOMPtr<nsISocketProviderService> inst = new nsSocketProviderService();
+  if (!inst)
+    rv = NS_ERROR_OUT_OF_MEMORY;
+  else
+    rv = inst->QueryInterface(aIID, aResult);
+  return rv;
+}
+
+NS_IMPL_ISUPPORTS(nsSocketProviderService, nsISocketProviderService)
+
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsSocketProviderService::GetSocketProvider(const char         *type,
+                                           nsISocketProvider **result)
+{
+  nsresult rv;
+  nsAutoCString contractID(
+          NS_LITERAL_CSTRING(NS_NETWORK_SOCKET_CONTRACTID_PREFIX) +
+          nsDependentCString(type));
+
+  rv = CallGetService(contractID.get(), result);
+  if (NS_FAILED(rv)) 
+      rv = NS_ERROR_UNKNOWN_SOCKET_TYPE;
+  return rv;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/netwerk/socket/nsSocketProviderService.h b/netwerk/socket/nsSocketProviderService.h
new file mode 100644
index 000000000..4082abcfa
--- /dev/null
+++ b/netwerk/socket/nsSocketProviderService.h
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSocketProviderService_h__
+#define nsSocketProviderService_h__
+
+#include "nsISocketProviderService.h"
+
+class nsSocketProviderService : public nsISocketProviderService
+{
+  virtual ~nsSocketProviderService() {}
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSISOCKETPROVIDERSERVICE
+
+  nsSocketProviderService() {}
+
+  static nsresult Create(nsISupports *, REFNSIID aIID, void **aResult);
+};
+
+#endif /* nsSocketProviderService_h__ */
diff --git a/netwerk/socket/nsUDPSocketProvider.cpp b/netwerk/socket/nsUDPSocketProvider.cpp
new file mode 100644
index 000000000..552c26ba2
--- /dev/null
+++ b/netwerk/socket/nsUDPSocketProvider.cpp
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsUDPSocketProvider.h"
+
+#include "nspr.h"
+
+using mozilla::NeckoOriginAttributes;
+
+NS_IMPL_ISUPPORTS(nsUDPSocketProvider, nsISocketProvider)
+
+nsUDPSocketProvider::~nsUDPSocketProvider()
+{
+}
+
+NS_IMETHODIMP 
+nsUDPSocketProvider::NewSocket(int32_t aFamily,
+                               const char *aHost, 
+                               int32_t aPort, 
+                               nsIProxyInfo *aProxy,
+                               const NeckoOriginAttributes &originAttributes,
+                               uint32_t aFlags,
+                               PRFileDesc * *aFileDesc, 
+                               nsISupports **aSecurityInfo)
+{
+    NS_ENSURE_ARG_POINTER(aFileDesc);
+  
+    PRFileDesc* udpFD = PR_OpenUDPSocket(aFamily);
+    if (!udpFD)
+        return NS_ERROR_FAILURE;
+  
+    *aFileDesc = udpFD;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsUDPSocketProvider::AddToSocket(int32_t aFamily,
+                                 const char *aHost,
+                                 int32_t aPort,
+                                 nsIProxyInfo *aProxy,
+                                 const NeckoOriginAttributes &originAttributes,
+                                 uint32_t aFlags,
+                                 struct PRFileDesc * aFileDesc,
+                                 nsISupports **aSecurityInfo)
+{
+    // does not make sense to strap a UDP socket onto an existing socket
+    NS_NOTREACHED("Cannot layer UDP socket on an existing socket");
+    return NS_ERROR_UNEXPECTED;
+}
diff --git a/netwerk/socket/nsUDPSocketProvider.h b/netwerk/socket/nsUDPSocketProvider.h
new file mode 100644
index 000000000..32c0e3b25
--- /dev/null
+++ b/netwerk/socket/nsUDPSocketProvider.h
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsUDPSocketProvider_h__
+#define nsUDPSocketProvider_h__
+
+#include "nsISocketProvider.h"
+#include "mozilla/Attributes.h"
+
+class nsUDPSocketProvider final : public nsISocketProvider
+{
+public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSISOCKETPROVIDER
+
+private:
+    ~nsUDPSocketProvider();
+
+};
+
+#endif /* nsUDPSocketProvider_h__ */
+