global: mass rewrite to use modern exception syntax
Python 2.6 introduced the "except type as instance" syntax, replacing
the "except type, instance" syntax that came before. Python 3 dropped
support for the latter syntax. Since we no longer support Python 2.4 or
2.5, we have no need to continue supporting the "except type, instance".
This patch mass rewrites the exception syntax to be Python 2.6+ and
Python 3 compatible.
This patch was produced by running `2to3 -f except -w -n .`.
# Copyright 2010, 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.
"""Improved HTTP/1.1 client library
This library contains an HTTPConnection which is similar to the one in
httplib, but has several additional features:
* supports keepalives natively
* uses select() to block for incoming data
* notices when the server responds early to a request
* implements ssl inline instead of in a different class
"""
# Many functions in this file have too many arguments.
# pylint: disable=R0913
import cStringIO
import errno
import httplib
import logging
import rfc822
import select
import socket
import _readers
import socketutil
logger = logging.getLogger(__name__)
__all__ = ['HTTPConnection', 'HTTPResponse']
HTTP_VER_1_0 = 'HTTP/1.0'
HTTP_VER_1_1 = 'HTTP/1.1'
OUTGOING_BUFFER_SIZE = 1 << 15
INCOMING_BUFFER_SIZE = 1 << 20
HDR_ACCEPT_ENCODING = 'accept-encoding'
HDR_CONNECTION_CTRL = 'connection'
HDR_CONTENT_LENGTH = 'content-length'
HDR_XFER_ENCODING = 'transfer-encoding'
XFER_ENCODING_CHUNKED = 'chunked'
CONNECTION_CLOSE = 'close'
EOL = '\r\n'
_END_HEADERS = EOL * 2
# Based on some searching around, 1 second seems like a reasonable
# default here.
TIMEOUT_ASSUME_CONTINUE = 1
TIMEOUT_DEFAULT = None
class HTTPResponse(object):
"""Response from an HTTP server.
The response will continue to load as available. If you need the
complete response before continuing, check the .complete() method.
"""
def __init__(self, sock, timeout, method):
self.sock = sock
self.method = method
self.raw_response = ''
self._headers_len = 0
self.headers = None
self.will_close = False
self.status_line = ''
self.status = None
self.continued = False
self.http_version = None
self.reason = None
self._reader = None
self._read_location = 0
self._eol = EOL
self._timeout = timeout
@property
def _end_headers(self):
return self._eol * 2
def complete(self):
"""Returns true if this response is completely loaded.
Note that if this is a connection where complete means the
socket is closed, this will nearly always return False, even
in cases where all the data has actually been loaded.
"""
if self._reader:
return self._reader.done()
def _close(self):
if self._reader is not None:
# We're a friend of the reader class here.
# pylint: disable=W0212
self._reader._close()
def readline(self):
"""Read a single line from the response body.
This may block until either a line ending is found or the
response is complete.
"""
blocks = []
while True:
self._reader.readto('\n', blocks)
if blocks and blocks[-1][-1] == '\n' or self.complete():
break
self._select()
return ''.join(blocks)
def read(self, length=None):
"""Read data from the response body."""
# if length is None, unbounded read
while (not self.complete() # never select on a finished read
and (not length # unbounded, so we wait for complete()
or length > self._reader.available_data)):
self._select()
if not length:
length = self._reader.available_data
r = self._reader.read(length)
if self.complete() and self.will_close:
self.sock.close()
return r
def _select(self):
r, unused_write, unused_err = select.select(
[self.sock], [], [], self._timeout)
if not r:
# socket was not readable. If the response is not
# complete, raise a timeout.
if not self.complete():
logger.info('timed out with timeout of %s', self._timeout)
raise HTTPTimeoutException('timeout reading data')
try:
data = self.sock.recv(INCOMING_BUFFER_SIZE)
except socket.sslerror as e:
if e.args[0] != socket.SSL_ERROR_WANT_READ:
raise
logger.debug('SSL_ERROR_WANT_READ in _select, should retry later')
return True
logger.debug('response read %d data during _select', len(data))
# If the socket was readable and no data was read, that means
# the socket was closed. Inform the reader (if any) so it can
# raise an exception if this is an invalid situation.
if not data:
if self._reader:
# We're a friend of the reader class here.
# pylint: disable=W0212
self._reader._close()
return False
else:
self._load_response(data)
return True
# This method gets replaced by _load later, which confuses pylint.
def _load_response(self, data): # pylint: disable=E0202
# Being here implies we're not at the end of the headers yet,
# since at the end of this method if headers were completely
# loaded we replace this method with the load() method of the
# reader we created.
self.raw_response += data
# This is a bogus server with bad line endings
if self._eol not in self.raw_response:
for bad_eol in ('\n', '\r'):
if (bad_eol in self.raw_response
# verify that bad_eol is not the end of the incoming data
# as this could be a response line that just got
# split between \r and \n.
and (self.raw_response.index(bad_eol) <
(len(self.raw_response) - 1))):
logger.info('bogus line endings detected, '
'using %r for EOL', bad_eol)
self._eol = bad_eol
break
# exit early if not at end of headers
if self._end_headers not in self.raw_response or self.headers:
return
# handle 100-continue response
hdrs, body = self.raw_response.split(self._end_headers, 1)
unused_http_ver, status = hdrs.split(' ', 1)
if status.startswith('100'):
self.raw_response = body
self.continued = True
logger.debug('continue seen, setting body to %r', body)
return
# arriving here means we should parse response headers
# as all headers have arrived completely
hdrs, body = self.raw_response.split(self._end_headers, 1)
del self.raw_response
if self._eol in hdrs:
self.status_line, hdrs = hdrs.split(self._eol, 1)
else:
self.status_line = hdrs
hdrs = ''
# TODO HTTP < 1.0 support
(self.http_version, self.status,
self.reason) = self.status_line.split(' ', 2)
self.status = int(self.status)
if self._eol != EOL:
hdrs = hdrs.replace(self._eol, '\r\n')
headers = rfc822.Message(cStringIO.StringIO(hdrs))
content_len = None
if HDR_CONTENT_LENGTH in headers:
content_len = int(headers[HDR_CONTENT_LENGTH])
if self.http_version == HTTP_VER_1_0:
self.will_close = True
elif HDR_CONNECTION_CTRL in headers:
self.will_close = (
headers[HDR_CONNECTION_CTRL].lower() == CONNECTION_CLOSE)
if (HDR_XFER_ENCODING in headers
and headers[HDR_XFER_ENCODING].lower() == XFER_ENCODING_CHUNKED):
self._reader = _readers.ChunkedReader(self._eol)
logger.debug('using a chunked reader')
else:
# HEAD responses are forbidden from returning a body, and
# it's implausible for a CONNECT response to use
# close-is-end logic for an OK response.
if (self.method == 'HEAD' or
(self.method == 'CONNECT' and content_len is None)):
content_len = 0
if content_len is not None:
logger.debug('using a content-length reader with length %d',
content_len)
self._reader = _readers.ContentLengthReader(content_len)
else:
# Response body had no length specified and is not
# chunked, so the end of the body will only be
# identifiable by the termination of the socket by the
# server. My interpretation of the spec means that we
# are correct in hitting this case if
# transfer-encoding, content-length, and
# connection-control were left unspecified.
self._reader = _readers.CloseIsEndReader()
logger.debug('using a close-is-end reader')
self.will_close = True
if body:
# We're a friend of the reader class here.
# pylint: disable=W0212
self._reader._load(body)
logger.debug('headers complete')
self.headers = headers
# We're a friend of the reader class here.
# pylint: disable=W0212
self._load_response = self._reader._load
class HTTPConnection(object):
"""Connection to a single http server.
Supports 100-continue and keepalives natively. Uses select() for
non-blocking socket operations.
"""
http_version = HTTP_VER_1_1
response_class = HTTPResponse
def __init__(self, host, port=None, use_ssl=None, ssl_validator=None,
timeout=TIMEOUT_DEFAULT,
continue_timeout=TIMEOUT_ASSUME_CONTINUE,
proxy_hostport=None, ssl_wrap_socket=None, **ssl_opts):
"""Create a new HTTPConnection.
Args:
host: The host to which we'll connect.
port: Optional. The port over which we'll connect. Default 80 for
non-ssl, 443 for ssl.
use_ssl: Optional. Whether to use ssl. Defaults to False if port is
not 443, true if port is 443.
ssl_validator: a function(socket) to validate the ssl cert
timeout: Optional. Connection timeout, default is TIMEOUT_DEFAULT.
continue_timeout: Optional. Timeout for waiting on an expected
"100 Continue" response. Default is TIMEOUT_ASSUME_CONTINUE.
proxy_hostport: Optional. Tuple of (host, port) to use as an http
proxy for the connection. Default is to not use a proxy.
ssl_wrap_socket: Optional function to use for wrapping
sockets. If unspecified, the one from the ssl module will
be used if available, or something that's compatible with
it if on a Python older than 2.6.
Any extra keyword arguments to this function will be provided
to the ssl_wrap_socket method. If no ssl
"""
if port is None and host.count(':') == 1 or ']:' in host:
host, port = host.rsplit(':', 1)
port = int(port)
if '[' in host:
host = host[1:-1]
if ssl_wrap_socket is not None:
self._ssl_wrap_socket = ssl_wrap_socket
else:
self._ssl_wrap_socket = socketutil.wrap_socket
if use_ssl is None and port is None:
use_ssl = False
port = 80
elif use_ssl is None:
use_ssl = (port == 443)
elif port is None:
if use_ssl:
port = 443
else:
port = 80
self.port = port
if use_ssl and not socketutil.have_ssl:
raise Exception('ssl requested but unavailable on this Python')
self.ssl = use_ssl
self.ssl_opts = ssl_opts
self._ssl_validator = ssl_validator
self.host = host
self.sock = None
self._current_response = None
self._current_response_taken = False
if proxy_hostport is None:
self._proxy_host = self._proxy_port = None
else:
self._proxy_host, self._proxy_port = proxy_hostport
self.timeout = timeout
self.continue_timeout = continue_timeout
def _connect(self):
"""Connect to the host and port specified in __init__."""
if self.sock:
return
if self._proxy_host is not None:
logger.info('Connecting to http proxy %s:%s',
self._proxy_host, self._proxy_port)
sock = socketutil.create_connection((self._proxy_host,
self._proxy_port))
if self.ssl:
# TODO proxy header support
data = self._buildheaders('CONNECT', '%s:%d' % (self.host,
self.port),
{}, HTTP_VER_1_0)
sock.send(data)
sock.setblocking(0)
r = self.response_class(sock, self.timeout, 'CONNECT')
timeout_exc = HTTPTimeoutException(
'Timed out waiting for CONNECT response from proxy')
while not r.complete():
try:
# We're a friend of the response class, so let
# us use the private attribute.
# pylint: disable=W0212
if not r._select():
if not r.complete():
raise timeout_exc
except HTTPTimeoutException:
# This raise/except pattern looks goofy, but
# _select can raise the timeout as well as the
# loop body. I wish it wasn't this convoluted,
# but I don't have a better solution
# immediately handy.
raise timeout_exc
if r.status != 200:
raise HTTPProxyConnectFailedException(
'Proxy connection failed: %d %s' % (r.status,
r.read()))
logger.info('CONNECT (for SSL) to %s:%s via proxy succeeded.',
self.host, self.port)
else:
sock = socketutil.create_connection((self.host, self.port))
if self.ssl:
# This is the default, but in the case of proxied SSL
# requests the proxy logic above will have cleared
# blocking mode, so re-enable it just to be safe.
sock.setblocking(1)
logger.debug('wrapping socket for ssl with options %r',
self.ssl_opts)
sock = self._ssl_wrap_socket(sock, **self.ssl_opts)
if self._ssl_validator:
self._ssl_validator(sock)
sock.setblocking(0)
self.sock = sock
def _buildheaders(self, method, path, headers, http_ver):
if self.ssl and self.port == 443 or self.port == 80:
# default port for protocol, so leave it out
hdrhost = self.host
else:
# include nonstandard port in header
if ':' in self.host: # must be IPv6
hdrhost = '[%s]:%d' % (self.host, self.port)
else:
hdrhost = '%s:%d' % (self.host, self.port)
if self._proxy_host and not self.ssl:
# When talking to a regular http proxy we must send the
# full URI, but in all other cases we must not (although
# technically RFC 2616 says servers must accept our
# request if we screw up, experimentally few do that
# correctly.)
assert path[0] == '/', 'path must start with a /'
path = 'http://%s%s' % (hdrhost, path)
outgoing = ['%s %s %s%s' % (method, path, http_ver, EOL)]
headers['host'] = ('Host', hdrhost)
headers[HDR_ACCEPT_ENCODING] = (HDR_ACCEPT_ENCODING, 'identity')
for hdr, val in headers.itervalues():
outgoing.append('%s: %s%s' % (hdr, val, EOL))
outgoing.append(EOL)
return ''.join(outgoing)
def close(self):
"""Close the connection to the server.
This is a no-op if the connection is already closed. The
connection may automatically close if requested by the server
or required by the nature of a response.
"""
if self.sock is None:
return
self.sock.close()
self.sock = None
logger.info('closed connection to %s on %s', self.host, self.port)
def busy(self):
"""Returns True if this connection object is currently in use.
If a response is still pending, this will return True, even if
the request has finished sending. In the future,
HTTPConnection may transparently juggle multiple connections
to the server, in which case this will be useful to detect if
any of those connections is ready for use.
"""
cr = self._current_response
if cr is not None:
if self._current_response_taken:
if cr.will_close:
self.sock = None
self._current_response = None
return False
elif cr.complete():
self._current_response = None
return False
return True
return False
def _reconnect(self, where):
logger.info('reconnecting during %s', where)
self.close()
self._connect()
def request(self, method, path, body=None, headers={},
expect_continue=False):
"""Send a request to the server.
For increased flexibility, this does not return the response
object. Future versions of HTTPConnection that juggle multiple
sockets will be able to send (for example) 5 requests all at
once, and then let the requests arrive as data is
available. Use the `getresponse()` method to retrieve the
response.
"""
if self.busy():
raise httplib.CannotSendRequest(
'Can not send another request before '
'current response is read!')
self._current_response_taken = False
logger.info('sending %s request for %s to %s on port %s',
method, path, self.host, self.port)
hdrs = dict((k.lower(), (k, v)) for k, v in headers.iteritems())
if hdrs.get('expect', ('', ''))[1].lower() == '100-continue':
expect_continue = True
elif expect_continue:
hdrs['expect'] = ('Expect', '100-Continue')
chunked = False
if body and HDR_CONTENT_LENGTH not in hdrs:
if getattr(body, '__len__', False):
hdrs[HDR_CONTENT_LENGTH] = (HDR_CONTENT_LENGTH, len(body))
elif getattr(body, 'read', False):
hdrs[HDR_XFER_ENCODING] = (HDR_XFER_ENCODING,
XFER_ENCODING_CHUNKED)
chunked = True
else:
raise BadRequestData('body has no __len__() nor read()')
# If we're reusing the underlying socket, there are some
# conditions where we'll want to retry, so make a note of the
# state of self.sock
fresh_socket = self.sock is None
self._connect()
outgoing_headers = self._buildheaders(
method, path, hdrs, self.http_version)
response = None
first = True
while ((outgoing_headers or body)
and not (response and response.complete())):
select_timeout = self.timeout
out = outgoing_headers or body
blocking_on_continue = False
if expect_continue and not outgoing_headers and not (
response and (response.headers or response.continued)):
logger.info(
'waiting up to %s seconds for'
' continue response from server',
self.continue_timeout)
select_timeout = self.continue_timeout
blocking_on_continue = True
out = False
if out:
w = [self.sock]
else:
w = []
r, w, x = select.select([self.sock], w, [], select_timeout)
# if we were expecting a 100 continue and it's been long
# enough, just go ahead and assume it's ok. This is the
# recommended behavior from the RFC.
if r == w == x == []:
if blocking_on_continue:
expect_continue = False
logger.info('no response to continue expectation from '
'server, optimistically sending request body')
else:
raise HTTPTimeoutException('timeout sending data')
was_first = first
# incoming data
if r:
try:
try:
data = r[0].recv(INCOMING_BUFFER_SIZE)
except socket.sslerror as e:
if e.args[0] != socket.SSL_ERROR_WANT_READ:
raise
logger.debug('SSL_ERROR_WANT_READ while sending '
'data, retrying...')
continue
if not data:
logger.info('socket appears closed in read')
self.sock = None
self._current_response = None
if response is not None:
# We're a friend of the response class, so let
# us use the private attribute.
# pylint: disable=W0212
response._close()
# This if/elif ladder is a bit subtle,
# comments in each branch should help.
if response is not None and response.complete():
# Server responded completely and then
# closed the socket. We should just shut
# things down and let the caller get their
# response.
logger.info('Got an early response, '
'aborting remaining request.')
break
elif was_first and response is None:
# Most likely a keepalive that got killed
# on the server's end. Commonly happens
# after getting a really large response
# from the server.
logger.info(
'Connection appeared closed in read on first'
' request loop iteration, will retry.')
self._reconnect('read')
continue
else:
# We didn't just send the first data hunk,
# and either have a partial response or no
# response at all. There's really nothing
# meaningful we can do here.
raise HTTPStateError(
'Connection appears closed after '
'some request data was written, but the '
'response was missing or incomplete!')
logger.debug('read %d bytes in request()', len(data))
if response is None:
response = self.response_class(
r[0], self.timeout, method)
# We're a friend of the response class, so let us
# use the private attribute.
# pylint: disable=W0212
response._load_response(data)
# Jump to the next select() call so we load more
# data if the server is still sending us content.
continue
except socket.error as e:
if e[0] != errno.EPIPE and not was_first:
raise
# outgoing data
if w and out:
try:
if getattr(out, 'read', False):
# pylint guesses the type of out incorrectly here
# pylint: disable=E1103
data = out.read(OUTGOING_BUFFER_SIZE)
if not data:
continue
if len(data) < OUTGOING_BUFFER_SIZE:
if chunked:
body = '0' + EOL + EOL
else:
body = None
if chunked:
out = hex(len(data))[2:] + EOL + data + EOL
else:
out = data
amt = w[0].send(out)
except socket.error as e:
if e[0] == socket.SSL_ERROR_WANT_WRITE and self.ssl:
# This means that SSL hasn't flushed its buffer into
# the socket yet.
# TODO: find a way to block on ssl flushing its buffer
# similar to selecting on a raw socket.
continue
if e[0] == errno.EWOULDBLOCK or e[0] == errno.EAGAIN:
continue
elif (e[0] not in (errno.ECONNRESET, errno.EPIPE)
and not first):
raise
self._reconnect('write')
amt = self.sock.send(out)
logger.debug('sent %d', amt)
first = False
if out is body:
body = out[amt:]
else:
outgoing_headers = out[amt:]
# close if the server response said to or responded before eating
# the whole request
if response is None:
response = self.response_class(self.sock, self.timeout, method)
if not fresh_socket:
if not response._select():
# This means the response failed to get any response
# data at all, and in all probability the socket was
# closed before the server even saw our request. Try
# the request again on a fresh socket.
logging.debug('response._select() failed during request().'
' Assuming request needs to be retried.')
self.sock = None
# Call this method explicitly to re-try the
# request. We don't use self.request() because
# some tools (notably Mercurial) expect to be able
# to subclass and redefine request(), and they
# don't have the same argspec as we do.
#
# TODO restructure sending of requests to avoid
# this recursion
return HTTPConnection.request(
self, method, path, body=body, headers=headers,
expect_continue=expect_continue)
data_left = bool(outgoing_headers or body)
if data_left:
logger.info('stopped sending request early, '
'will close the socket to be safe.')
response.will_close = True
if response.will_close:
# The socket will be closed by the response, so we disown
# the socket
self.sock = None
self._current_response = response
def getresponse(self):
"""Returns the response to the most recent request."""
if self._current_response is None:
raise httplib.ResponseNotReady()
r = self._current_response
while r.headers is None:
# We're a friend of the response class, so let us use the
# private attribute.
# pylint: disable=W0212
if not r._select() and not r.complete():
raise _readers.HTTPRemoteClosedError()
if r.will_close:
self.sock = None
self._current_response = None
elif r.complete():
self._current_response = None
else:
self._current_response_taken = True
return r
class HTTPTimeoutException(httplib.HTTPException):
"""A timeout occurred while waiting on the server."""
class BadRequestData(httplib.HTTPException):
"""Request body object has neither __len__ nor read."""
class HTTPProxyConnectFailedException(httplib.HTTPException):
"""Connecting to the HTTP proxy failed."""
class HTTPStateError(httplib.HTTPException):
"""Invalid internal state encountered."""
# Forward this exception type from _readers since it needs to be part
# of the public API.
HTTPRemoteClosedError = _readers.HTTPRemoteClosedError
# no-check-code