Mercurial > hg
view mercurial/httpclient/__init__.py @ 15218:c81dce8a7bb6
httpclient: update to 07d8c356f4d1 of py-nonblocking-http
This addresses a defect when the server closes the socket before
finishing a response (if it crashes, for example) first spotted in
Issue2951.
author | Augie Fackler <durin42@gmail.com> |
---|---|
date | Mon, 10 Oct 2011 17:57:40 -0500 |
parents | a75e0f4ba0ab |
children | 24dbef11f477 |
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# 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 """ import cStringIO import errno import httplib import logging import rfc822 import select import socket import socketutil logger = logging.getLogger(__name__) __all__ = ['HTTPConnection', 'HTTPResponse'] HTTP_VER_1_0 = 'HTTP/1.0' HTTP_VER_1_1 = 'HTTP/1.1' _LEN_CLOSE_IS_END = -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): self.sock = sock self.raw_response = '' self._body = None self._headers_len = 0 self._content_len = 0 self.headers = None self.will_close = False self.status_line = '' self.status = None self.http_version = None self.reason = None self._chunked = False self._chunked_done = False self._chunked_until_next = 0 self._chunked_skip_bytes = 0 self._chunked_preloaded_block = 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._chunked: return self._chunked_done if self._content_len == _LEN_CLOSE_IS_END: return False return self._body is not None and len(self._body) >= self._content_len 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. """ eol = self._body.find('\n', self._read_location) while eol == -1 and not self.complete(): self._select() eol = self._body.find('\n', self._read_location) if eol != -1: eol += 1 else: eol = len(self._body) data = self._body[self._read_location:eol] self._read_location = eol return data def read(self, length=None): # 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 (self._read_location + length) > len(self._body))): self._select() if not length: length = len(self._body) - self._read_location elif len(self._body) < (self._read_location + length): length = len(self._body) - self._read_location r = self._body[self._read_location:self._read_location + length] self._read_location += len(r) if self.complete() and self.will_close: self.sock.close() return r def _select(self): r, _, _ = select.select([self.sock], [], [], self._timeout) if not r: # socket was not readable. If the response is not complete # and we're not a _LEN_CLOSE_IS_END response, raise a timeout. # If we are a _LEN_CLOSE_IS_END response and we have no data, # raise a timeout. if not (self.complete() or (self._content_len == _LEN_CLOSE_IS_END and self._body)): logger.info('timed out with timeout of %s', self._timeout) raise HTTPTimeoutException('timeout reading data') logger.info('cl: %r body: %r', self._content_len, self._body) try: data = self.sock.recv(INCOMING_BUFFER_SIZE) # If the socket was readable and no data was read, that # means the socket was closed. If this isn't a # _CLOSE_IS_END socket, then something is wrong if we're # here (we shouldn't enter _select() if the response is # complete), so abort. if not data and self._content_len != _LEN_CLOSE_IS_END: raise HTTPRemoteClosedError( 'server appears to have closed the socket mid-response') except socket.sslerror, e: if e.args[0] != socket.SSL_ERROR_WANT_READ: raise logger.debug('SSL_WANT_READ in _select, should retry later') return True logger.debug('response read %d data during _select', len(data)) if not data: if self.headers and self._content_len == _LEN_CLOSE_IS_END: self._content_len = len(self._body) return False else: self._load_response(data) return True def _chunked_parsedata(self, data): if self._chunked_preloaded_block: data = self._chunked_preloaded_block + data self._chunked_preloaded_block = None while data: logger.debug('looping with %d data remaining', len(data)) # Slice out anything we should skip if self._chunked_skip_bytes: if len(data) <= self._chunked_skip_bytes: self._chunked_skip_bytes -= len(data) data = '' break else: data = data[self._chunked_skip_bytes:] self._chunked_skip_bytes = 0 # determine how much is until the next chunk if self._chunked_until_next: amt = self._chunked_until_next logger.debug('reading remaining %d of existing chunk', amt) self._chunked_until_next = 0 body = data else: try: amt, body = data.split(self._eol, 1) except ValueError: self._chunked_preloaded_block = data logger.debug('saving %r as a preloaded block for chunked', self._chunked_preloaded_block) return amt = int(amt, base=16) logger.debug('reading chunk of length %d', amt) if amt == 0: self._chunked_done = True # read through end of what we have or the chunk self._body += body[:amt] if len(body) >= amt: data = body[amt:] self._chunked_skip_bytes = len(self._eol) else: self._chunked_until_next = amt - len(body) self._chunked_skip_bytes = 0 data = '' def _load_response(self, data): if self._chunked: self._chunked_parsedata(data) return elif self._body is not None: self._body += data return # We haven't seen end of headers yet 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) http_ver, status = hdrs.split(' ', 1) if status.startswith('100'): self.raw_response = body 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)) if HDR_CONTENT_LENGTH in headers: self._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 self._content_len == 0: self._content_len = _LEN_CLOSE_IS_END if (HDR_XFER_ENCODING in headers and headers[HDR_XFER_ENCODING].lower() == XFER_ENCODING_CHUNKED): self._body = '' self._chunked_parsedata(body) self._chunked = True if self._body is None: self._body = body self.headers = headers 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_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. Wether 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. """ 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 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: port = (use_ssl and 443 or 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) timeout_exc = HTTPTimeoutException( 'Timed out waiting for CONNECT response from proxy') while not r.complete(): try: if not r._select(): 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: logger.debug('wrapping socket for ssl with options %r', self.ssl_opts) sock = socketutil.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 requessted 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 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()') self._connect() outgoing_headers = self.buildheaders( method, path, hdrs, self.http_version) response = None first = True def reconnect(where): logger.info('reconnecting during %s', where) self.close() self._connect() 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): 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') # TODO exceptional conditions with select? (what are those be?) # TODO if the response is loading, must we finish sending at all? # # Certainly not if it's going to close the connection and/or # the response is already done...I think. was_first = first # incoming data if r: try: try: data = r[0].recv(INCOMING_BUFFER_SIZE) except socket.sslerror, e: if e.args[0] != socket.SSL_ERROR_WANT_READ: raise logger.debug( 'SSL_WANT_READ while sending data, retrying...') continue if not data: logger.info('socket appears closed in read') self.sock = None self._current_response = None # This if/elif ladder is a bit subtle, # comments in each branch should help. if response is not None and ( response.complete() or response._content_len == _LEN_CLOSE_IS_END): # 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.') 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) 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, e: if e[0] != errno.EPIPE and not was_first: raise if (response._content_len and response._content_len != _LEN_CLOSE_IS_END): outgoing_headers = sent_data + outgoing_headers reconnect('read') # outgoing data if w and out: try: if getattr(out, 'read', False): 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, 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 elif (e[0] not in (errno.ECONNRESET, errno.EPIPE) and not first): raise reconnect('write') amt = self.sock.send(out) logger.debug('sent %d', amt) first = False # stash data we think we sent in case the socket breaks # when we read from it if was_first: sent_data = out[:amt] 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) complete = response.complete() 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): if self._current_response is None: raise httplib.ResponseNotReady() r = self._current_response while r.headers is None: r._select() 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.""" class HTTPRemoteClosedError(httplib.HTTPException): """The server closed the remote socket in the middle of a response.""" # no-check-code