# 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