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# Copyright 2011, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""Base stream class.
"""
# Note: request.connection.write/read are used in this module, even though
# mod_python document says that they should be used only in connection
# handlers. Unfortunately, we have no other options. For example,
# request.write/read are not suitable because they don't allow direct raw bytes
# writing/reading.
import socket
from mod_pywebsocket import util
# Exceptions
class ConnectionTerminatedException(Exception):
"""This exception will be raised when a connection is terminated
unexpectedly.
"""
pass
class InvalidFrameException(ConnectionTerminatedException):
"""This exception will be raised when we received an invalid frame we
cannot parse.
"""
pass
class BadOperationException(Exception):
"""This exception will be raised when send_message() is called on
server-terminated connection or receive_message() is called on
client-terminated connection.
"""
pass
class UnsupportedFrameException(Exception):
"""This exception will be raised when we receive a frame with flag, opcode
we cannot handle. Handlers can just catch and ignore this exception and
call receive_message() again to continue processing the next frame.
"""
pass
class InvalidUTF8Exception(Exception):
"""This exception will be raised when we receive a text frame which
contains invalid UTF-8 strings.
"""
pass
class StreamBase(object):
"""Base stream class."""
def __init__(self, request):
"""Construct an instance.
Args:
request: mod_python request.
"""
self._logger = util.get_class_logger(self)
self._request = request
def _read(self, length):
"""Reads length bytes from connection. In case we catch any exception,
prepends remote address to the exception message and raise again.
Raises:
ConnectionTerminatedException: when read returns empty string.
"""
try:
read_bytes = self._request.connection.read(length)
if not read_bytes:
raise ConnectionTerminatedException(
'Receiving %d byte failed. Peer (%r) closed connection' %
(length, (self._request.connection.remote_addr,)))
return read_bytes
except socket.error, e:
# Catch a socket.error. Because it's not a child class of the
# IOError prior to Python 2.6, we cannot omit this except clause.
# Use %s rather than %r for the exception to use human friendly
# format.
raise ConnectionTerminatedException(
'Receiving %d byte failed. socket.error (%s) occurred' %
(length, e))
except IOError, e:
# Also catch an IOError because mod_python throws it.
raise ConnectionTerminatedException(
'Receiving %d byte failed. IOError (%s) occurred' %
(length, e))
def _write(self, bytes_to_write):
"""Writes given bytes to connection. In case we catch any exception,
prepends remote address to the exception message and raise again.
"""
try:
self._request.connection.write(bytes_to_write)
except Exception, e:
util.prepend_message_to_exception(
'Failed to send message to %r: ' %
(self._request.connection.remote_addr,),
e)
raise
def receive_bytes(self, length):
"""Receives multiple bytes. Retries read when we couldn't receive the
specified amount.
Raises:
ConnectionTerminatedException: when read returns empty string.
"""
read_bytes = []
while length > 0:
new_read_bytes = self._read(length)
read_bytes.append(new_read_bytes)
length -= len(new_read_bytes)
return ''.join(read_bytes)
def _read_until(self, delim_char):
"""Reads bytes until we encounter delim_char. The result will not
contain delim_char.
Raises:
ConnectionTerminatedException: when read returns empty string.
"""
read_bytes = []
while True:
ch = self._read(1)
if ch == delim_char:
break
read_bytes.append(ch)
return ''.join(read_bytes)
# vi:sts=4 sw=4 et
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