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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.
"""Utilities for parsing and formatting headers that follow the grammar defined
in HTTP RFC http://www.ietf.org/rfc/rfc2616.txt.
"""
import urlparse
_SEPARATORS = '()<>@,;:\\"/[]?={} \t'
def _is_char(c):
"""Returns true iff c is in CHAR as specified in HTTP RFC."""
return ord(c) <= 127
def _is_ctl(c):
"""Returns true iff c is in CTL as specified in HTTP RFC."""
return ord(c) <= 31 or ord(c) == 127
class ParsingState(object):
def __init__(self, data):
self.data = data
self.head = 0
def peek(state, pos=0):
"""Peeks the character at pos from the head of data."""
if state.head + pos >= len(state.data):
return None
return state.data[state.head + pos]
def consume(state, amount=1):
"""Consumes specified amount of bytes from the head and returns the
consumed bytes. If there's not enough bytes to consume, returns None.
"""
if state.head + amount > len(state.data):
return None
result = state.data[state.head:state.head + amount]
state.head = state.head + amount
return result
def consume_string(state, expected):
"""Given a parsing state and a expected string, consumes the string from
the head. Returns True if consumed successfully. Otherwise, returns
False.
"""
pos = 0
for c in expected:
if c != peek(state, pos):
return False
pos += 1
consume(state, pos)
return True
def consume_lws(state):
"""Consumes a LWS from the head. Returns True if any LWS is consumed.
Otherwise, returns False.
LWS = [CRLF] 1*( SP | HT )
"""
original_head = state.head
consume_string(state, '\r\n')
pos = 0
while True:
c = peek(state, pos)
if c == ' ' or c == '\t':
pos += 1
else:
if pos == 0:
state.head = original_head
return False
else:
consume(state, pos)
return True
def consume_lwses(state):
"""Consumes *LWS from the head."""
while consume_lws(state):
pass
def consume_token(state):
"""Consumes a token from the head. Returns the token or None if no token
was found.
"""
pos = 0
while True:
c = peek(state, pos)
if c is None or c in _SEPARATORS or _is_ctl(c) or not _is_char(c):
if pos == 0:
return None
return consume(state, pos)
else:
pos += 1
def consume_token_or_quoted_string(state):
"""Consumes a token or a quoted-string, and returns the token or unquoted
string. If no token or quoted-string was found, returns None.
"""
original_head = state.head
if not consume_string(state, '"'):
return consume_token(state)
result = []
expect_quoted_pair = False
while True:
if not expect_quoted_pair and consume_lws(state):
result.append(' ')
continue
c = consume(state)
if c is None:
# quoted-string is not enclosed with double quotation
state.head = original_head
return None
elif expect_quoted_pair:
expect_quoted_pair = False
if _is_char(c):
result.append(c)
else:
# Non CHAR character found in quoted-pair
state.head = original_head
return None
elif c == '\\':
expect_quoted_pair = True
elif c == '"':
return ''.join(result)
elif _is_ctl(c):
# Invalid character %r found in qdtext
state.head = original_head
return None
else:
result.append(c)
def quote_if_necessary(s):
"""Quotes arbitrary string into quoted-string."""
quote = False
if s == '':
return '""'
result = []
for c in s:
if c == '"' or c in _SEPARATORS or _is_ctl(c) or not _is_char(c):
quote = True
if c == '"' or _is_ctl(c):
result.append('\\' + c)
else:
result.append(c)
if quote:
return '"' + ''.join(result) + '"'
else:
return ''.join(result)
def parse_uri(uri):
"""Parse absolute URI then return host, port and resource."""
parsed = urlparse.urlsplit(uri)
if parsed.scheme != 'wss' and parsed.scheme != 'ws':
# |uri| must be a relative URI.
# TODO(toyoshim): Should validate |uri|.
return None, None, uri
if parsed.hostname is None:
return None, None, None
port = None
try:
port = parsed.port
except ValueError, e:
# port property cause ValueError on invalid null port description like
# 'ws://host:/path'.
return None, None, None
if port is None:
if parsed.scheme == 'ws':
port = 80
else:
port = 443
path = parsed.path
if not path:
path += '/'
if parsed.query:
path += '?' + parsed.query
if parsed.fragment:
path += '#' + parsed.fragment
return parsed.hostname, port, path
try:
urlparse.uses_netloc.index('ws')
except ValueError, e:
# urlparse in Python2.5.1 doesn't have 'ws' and 'wss' entries.
urlparse.uses_netloc.append('ws')
urlparse.uses_netloc.append('wss')
# vi:sts=4 sw=4 et
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