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Wrap

Python Source | 2001-07-26 | 28.4 KB | 843 lines

"""HTTP/1.1 client library <intro stuff goes here> <other stuff, too> HTTPConnection go through a number of "states", which defines when a client may legally make another request or fetch the response for a particular request. This diagram details these state transitions: (null) | | HTTPConnection() v Idle | | putrequest() v Request-started | | ( putheader() )* endheaders() v Request-sent | | response = getresponse() v Unread-response [Response-headers-read] |\____________________ | | | response.read() | putrequest() v v Idle Req-started-unread-response ______/| / | response.read() | | ( putheader() )* endheaders() v v Request-started Req-sent-unread-response | | response.read() v Request-sent This diagram presents the following rules: -- a second request may not be started until {response-headers-read} -- a response [object] cannot be retrieved until {request-sent} -- there is no differentiation between an unread response body and a partially read response body Note: this enforcement is applied by the HTTPConnection class. The HTTPResponse class does not enforce this state machine, which implies sophisticated clients may accelerate the request/response pipeline. Caution should be taken, though: accelerating the states beyond the above pattern may imply knowledge of the server's connection-close behavior for certain requests. For example, it is impossible to tell whether the server will close the connection UNTIL the response headers have been read; this means that further requests cannot be placed into the pipeline until it is known that the server will NOT be closing the connection. Logical State __state __response ------------- ------- ---------- Idle _CS_IDLE None Request-started _CS_REQ_STARTED None Request-sent _CS_REQ_SENT None Unread-response _CS_IDLE <response_class> Req-started-unread-response _CS_REQ_STARTED <response_class> Req-sent-unread-response _CS_REQ_SENT <response_class> """ import socket import mimetools try: from cStringIO import StringIO except ImportError: from StringIO import StringIO __all__ = ["HTTP", "HTTPResponse", "HTTPConnection", "HTTPSConnection", "HTTPException", "NotConnected", "UnknownProtocol", "UnknownTransferEncoding", "IllegalKeywordArgument", "UnimplementedFileMode", "IncompleteRead", "ImproperConnectionState", "CannotSendRequest", "CannotSendHeader", "ResponseNotReady", "BadStatusLine", "error"] HTTP_PORT = 80 HTTPS_PORT = 443 _UNKNOWN = 'UNKNOWN' # connection states _CS_IDLE = 'Idle' _CS_REQ_STARTED = 'Request-started' _CS_REQ_SENT = 'Request-sent' class HTTPResponse: def __init__(self, sock, debuglevel=0): self.fp = sock.makefile('rb', 0) self.debuglevel = debuglevel self.msg = None # from the Status-Line of the response self.version = _UNKNOWN # HTTP-Version self.status = _UNKNOWN # Status-Code self.reason = _UNKNOWN # Reason-Phrase self.chunked = _UNKNOWN # is "chunked" being used? self.chunk_left = _UNKNOWN # bytes left to read in current chunk self.length = _UNKNOWN # number of bytes left in response self.will_close = _UNKNOWN # conn will close at end of response def begin(self): if self.msg is not None: # we've already started reading the response return line = self.fp.readline() if self.debuglevel > 0: print "reply:", repr(line) try: [version, status, reason] = line.split(None, 2) except ValueError: try: [version, status] = line.split(None, 1) reason = "" except ValueError: version = "HTTP/0.9" status = "200" reason = "" if version[:5] != 'HTTP/': self.close() raise BadStatusLine(line) # The status code is a three-digit number try: self.status = status = int(status) if status < 100 or status > 999: raise BadStatusLine(line) except ValueError: raise BadStatusLine(line) self.reason = reason.strip() if version == 'HTTP/1.0': self.version = 10 elif version.startswith('HTTP/1.'): self.version = 11 # use HTTP/1.1 code for HTTP/1.x where x>=1 elif version == 'HTTP/0.9': self.version = 9 else: raise UnknownProtocol(version) if self.version == 9: self.msg = mimetools.Message(StringIO()) return self.msg = mimetools.Message(self.fp, 0) if self.debuglevel > 0: for hdr in self.msg.headers: print "header:", hdr, # don't let the msg keep an fp self.msg.fp = None # are we using the chunked-style of transfer encoding? tr_enc = self.msg.getheader('transfer-encoding') if tr_enc: if tr_enc.lower() != 'chunked': raise UnknownTransferEncoding() self.chunked = 1 self.chunk_left = None else: self.chunked = 0 # will the connection close at the end of the response? conn = self.msg.getheader('connection') if conn: conn = conn.lower() # a "Connection: close" will always close the connection. if we # don't see that and this is not HTTP/1.1, then the connection will # close unless we see a Keep-Alive header. self.will_close = conn.find('close') != -1 or \ ( self.version != 11 and \ not self.msg.getheader('keep-alive') ) else: # for HTTP/1.1, the connection will always remain open # otherwise, it will remain open IFF we see a Keep-Alive header self.will_close = self.version != 11 and \ not self.msg.getheader('keep-alive') # do we have a Content-Length? # NOTE: RFC 2616, S4.4, #3 says we ignore this if tr_enc is "chunked" length = self.msg.getheader('content-length') if length and not self.chunked: try: self.length = int(length) except ValueError: self.length = None else: self.length = None # does the body have a fixed length? (of zero) if (status == 204 or # No Content status == 304 or # Not Modified 100 <= status < 200): # 1xx codes self.length = 0 # if the connection remains open, and we aren't using chunked, and # a content-length was not provided, then assume that the connection # WILL close. if not self.will_close and \ not self.chunked and \ self.length is None: self.will_close = 1 def close(self): if self.fp: self.fp.close() self.fp = None def isclosed(self): # NOTE: it is possible that we will not ever call self.close(). This # case occurs when will_close is TRUE, length is None, and we # read up to the last byte, but NOT past it. # # IMPLIES: if will_close is FALSE, then self.close() will ALWAYS be # called, meaning self.isclosed() is meaningful. return self.fp is None def read(self, amt=None): if self.fp is None: return '' if self.chunked: chunk_left = self.chunk_left value = '' while 1: if chunk_left is None: line = self.fp.readline() i = line.find(';') if i >= 0: line = line[:i] # strip chunk-extensions chunk_left = int(line, 16) if chunk_left == 0: break if amt is None: value = value + self._safe_read(chunk_left) elif amt < chunk_left: value = value + self._safe_read(amt) self.chunk_left = chunk_left - amt return value elif amt == chunk_left: value = value + self._safe_read(amt) self._safe_read(2) # toss the CRLF at the end of the chunk self.chunk_left = None return value else: value = value + self._safe_read(chunk_left) amt = amt - chunk_left # we read the whole chunk, get another self._safe_read(2) # toss the CRLF at the end of the chunk chunk_left = None # read and discard trailer up to the CRLF terminator ### note: we shouldn't have any trailers! while 1: line = self.fp.readline() if line == '\r\n': break # we read everything; close the "file" self.close() return value elif amt is None: # unbounded read if self.will_close: s = self.fp.read() else: s = self._safe_read(self.length) self.close() # we read everything return s if self.length is not None: if amt > self.length: # clip the read to the "end of response" amt = self.length self.length = self.length - amt # we do not use _safe_read() here because this may be a .will_close # connection, and the user is reading more bytes than will be provided # (for example, reading in 1k chunks) s = self.fp.read(amt) return s def _safe_read(self, amt): """Read the number of bytes requested, compensating for partial reads. Normally, we have a blocking socket, but a read() can be interrupted by a signal (resulting in a partial read). Note that we cannot distinguish between EOF and an interrupt when zero bytes have been read. IncompleteRead() will be raised in this situation. This function should be used when <amt> bytes "should" be present for reading. If the bytes are truly not available (due to EOF), then the IncompleteRead exception can be used to detect the problem. """ s = '' while amt > 0: chunk = self.fp.read(amt) if not chunk: raise IncompleteRead(s) s = s + chunk amt = amt - len(chunk) return s def getheader(self, name, default=None): if self.msg is None: raise ResponseNotReady() return self.msg.getheader(name, default) class HTTPConnection: _http_vsn = 11 _http_vsn_str = 'HTTP/1.1' response_class = HTTPResponse default_port = HTTP_PORT auto_open = 1 debuglevel = 0 def __init__(self, host, port=None): self.sock = None self.__response = None self.__state = _CS_IDLE self._set_hostport(host, port) def _set_hostport(self, host, port): if port is None: i = host.find(':') if i >= 0: port = int(host[i+1:]) host = host[:i] else: port = self.default_port self.host = host self.port = port def set_debuglevel(self, level): self.debuglevel = level def connect(self): """Connect to the host and port specified in __init__.""" self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) if self.debuglevel > 0: print "connect: (%s, %s)" % (self.host, self.port) self.sock.connect((self.host, self.port)) def close(self): """Close the connection to the HTTP server.""" if self.sock: self.sock.close() # close it manually... there may be other refs self.sock = None if self.__response: self.__response.close() self.__response = None self.__state = _CS_IDLE def send(self, str): """Send `str' to the server.""" if self.sock is None: if self.auto_open: self.connect() else: raise NotConnected() # send the data to the server. if we get a broken pipe, then close # the socket. we want to reconnect when somebody tries to send again. # # NOTE: we DO propagate the error, though, because we cannot simply # ignore the error... the caller will know if they can retry. if self.debuglevel > 0: print "send:", repr(str) try: self.sock.send(str) except socket.error, v: if v[0] == 32: # Broken pipe self.close() raise def putrequest(self, method, url): """Send a request to the server. `method' specifies an HTTP request method, e.g. 'GET'. `url' specifies the object being requested, e.g. '/index.html'. """ # check if a prior response has been completed if self.__response and self.__response.isclosed(): self.__response = None # # in certain cases, we cannot issue another request on this connection. # this occurs when: # 1) we are in the process of sending a request. (_CS_REQ_STARTED) # 2) a response to a previous request has signalled that it is going # to close the connection upon completion. # 3) the headers for the previous response have not been read, thus # we cannot determine whether point (2) is true. (_CS_REQ_SENT) # # if there is no prior response, then we can request at will. # # if point (2) is true, then we will have passed the socket to the # response (effectively meaning, "there is no prior response"), and # will open a new one when a new request is made. # # Note: if a prior response exists, then we *can* start a new request. # We are not allowed to begin fetching the response to this new # request, however, until that prior response is complete. # if self.__state == _CS_IDLE: self.__state = _CS_REQ_STARTED else: raise CannotSendRequest() if not url: url = '/' str = '%s %s %s\r\n' % (method, url, self._http_vsn_str) try: self.send(str) except socket.error, v: # trap 'Broken pipe' if we're allowed to automatically reconnect if v[0] != 32 or not self.auto_open: raise # try one more time (the socket was closed; this will reopen) self.send(str) if self._http_vsn == 11: # Issue some standard headers for better HTTP/1.1 compliance # this header is issued *only* for HTTP/1.1 connections. more # specifically, this means it is only issued when the client uses # the new HTTPConnection() class. backwards-compat clients will # be using HTTP/1.0 and those clients may be issuing this header # themselves. we should NOT issue it twice; some web servers (such # as Apache) barf when they see two Host: headers # if we need a non-standard port,include it in the header if self.port == HTTP_PORT: self.putheader('Host', self.host) else: self.putheader('Host', "%s:%s" % (self.host, self.port)) # note: we are assuming that clients will not attempt to set these # headers since *this* library must deal with the # consequences. this also means that when the supporting # libraries are updated to recognize other forms, then this # code should be changed (removed or updated). # we only want a Content-Encoding of "identity" since we don't # support encodings such as x-gzip or x-deflate. self.putheader('Accept-Encoding', 'identity') # we can accept "chunked" Transfer-Encodings, but no others # NOTE: no TE header implies *only* "chunked" #self.putheader('TE', 'chunked') # if TE is supplied in the header, then it must appear in a # Connection header. #self.putheader('Connection', 'TE') else: # For HTTP/1.0, the server will assume "not chunked" pass def putheader(self, header, value): """Send a request header line to the server. For example: h.putheader('Accept', 'text/html') """ if self.__state != _CS_REQ_STARTED: raise CannotSendHeader() str = '%s: %s\r\n' % (header, value) self.send(str) def endheaders(self): """Indicate that the last header line has been sent to the server.""" if self.__state == _CS_REQ_STARTED: self.__state = _CS_REQ_SENT else: raise CannotSendHeader() self.send('\r\n') def request(self, method, url, body=None, headers={}): """Send a complete request to the server.""" try: self._send_request(method, url, body, headers) except socket.error, v: # trap 'Broken pipe' if we're allowed to automatically reconnect if v[0] != 32 or not self.auto_open: raise # try one more time self._send_request(method, url, body, headers) def _send_request(self, method, url, body, headers): self.putrequest(method, url) if body: self.putheader('Content-Length', str(len(body))) for hdr, value in headers.items(): self.putheader(hdr, value) self.endheaders() if body: self.send(body) def getresponse(self): "Get the response from the server." # check if a prior response has been completed if self.__response and self.__response.isclosed(): self.__response = None # # if a prior response exists, then it must be completed (otherwise, we # cannot read this response's header to determine the connection-close # behavior) # # note: if a prior response existed, but was connection-close, then the # socket and response were made independent of this HTTPConnection # object since a new request requires that we open a whole new # connection # # this means the prior response had one of two states: # 1) will_close: this connection was reset and the prior socket and # response operate independently # 2) persistent: the response was retained and we await its # isclosed() status to become true. # if self.__state != _CS_REQ_SENT or self.__response: raise ResponseNotReady() if self.debuglevel > 0: response = self.response_class(self.sock, self.debuglevel) else: response = self.response_class(self.sock) response.begin() self.__state = _CS_IDLE if response.will_close: # this effectively passes the connection to the response self.close() else: # remember this, so we can tell when it is complete self.__response = response return response class FakeSocket: def __init__(self, sock, ssl): self.__sock = sock self.__ssl = ssl def makefile(self, mode, bufsize=None): """Return a readable file-like object with data from socket. This method offers only partial support for the makefile interface of a real socket. It only supports modes 'r' and 'rb' and the bufsize argument is ignored. The returned object contains *all* of the file data """ if mode != 'r' and mode != 'rb': raise UnimplementedFileMode() msgbuf = [] while 1: try: buf = self.__ssl.read() except socket.sslerror, msg: break if buf == '': break msgbuf.append(buf) return StringIO("".join(msgbuf)) def send(self, stuff, flags = 0): return self.__ssl.write(stuff) def recv(self, len = 1024, flags = 0): return self.__ssl.read(len) def __getattr__(self, attr): return getattr(self.__sock, attr) class HTTPSConnection(HTTPConnection): "This class allows communication via SSL." default_port = HTTPS_PORT def __init__(self, host, port=None, **x509): keys = x509.keys() try: keys.remove('key_file') except ValueError: pass try: keys.remove('cert_file') except ValueError: pass if keys: raise IllegalKeywordArgument() HTTPConnection.__init__(self, host, port) self.key_file = x509.get('key_file') self.cert_file = x509.get('cert_file') def connect(self): "Connect to a host on a given (SSL) port." sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((self.host, self.port)) realsock = sock if hasattr(sock, "_sock"): realsock = sock._sock ssl = socket.ssl(realsock, self.key_file, self.cert_file) self.sock = FakeSocket(sock, ssl) class HTTP: "Compatibility class with httplib.py from 1.5." _http_vsn = 10 _http_vsn_str = 'HTTP/1.0' debuglevel = 0 _connection_class = HTTPConnection def __init__(self, host='', port=None, **x509): "Provide a default host, since the superclass requires one." # some joker passed 0 explicitly, meaning default port if port == 0: port = None # Note that we may pass an empty string as the host; this will throw # an error when we attempt to connect. Presumably, the client code # will call connect before then, with a proper host. self._conn = self._connection_class(host, port) # set up delegation to flesh out interface self.send = self._conn.send self.putrequest = self._conn.putrequest self.endheaders = self._conn.endheaders self._conn._http_vsn = self._http_vsn self._conn._http_vsn_str = self._http_vsn_str # we never actually use these for anything, but we keep them here for # compatibility with post-1.5.2 CVS. self.key_file = x509.get('key_file') self.cert_file = x509.get('cert_file') self.file = None def connect(self, host=None, port=None): "Accept arguments to set the host/port, since the superclass doesn't." if host is not None: self._conn._set_hostport(host, port) self._conn.connect() def set_debuglevel(self, debuglevel): self._conn.set_debuglevel(debuglevel) def getfile(self): "Provide a getfile, since the superclass' does not use this concept." return self.file def putheader(self, header, *values): "The superclass allows only one value argument." self._conn.putheader(header, '\r\n\t'.join(values)) def getreply(self): """Compat definition since superclass does not define it. Returns a tuple consisting of: - server status code (e.g. '200' if all goes well) - server "reason" corresponding to status code - any RFC822 headers in the response from the server """ try: response = self._conn.getresponse() except BadStatusLine, e: ### hmm. if getresponse() ever closes the socket on a bad request, ### then we are going to have problems with self.sock ### should we keep this behavior? do people use it? # keep the socket open (as a file), and return it self.file = self._conn.sock.makefile('rb', 0) # close our socket -- we want to restart after any protocol error self.close() self.headers = None return -1, e.line, None self.headers = response.msg self.file = response.fp return response.status, response.reason, response.msg def close(self): self._conn.close() # note that self.file == response.fp, which gets closed by the # superclass. just clear the object ref here. ### hmm. messy. if status==-1, then self.file is owned by us. ### well... we aren't explicitly closing, but losing this ref will ### do it self.file = None if hasattr(socket, 'ssl'): class HTTPS(HTTP): """Compatibility with 1.5 httplib interface Python 1.5.2 did not have an HTTPS class, but it defined an interface for sending http requests that is also useful for https. """ _connection_class = HTTPSConnection class HTTPException(Exception): pass class NotConnected(HTTPException): pass class UnknownProtocol(HTTPException): def __init__(self, version): self.version = version class UnknownTransferEncoding(HTTPException): pass class IllegalKeywordArgument(HTTPException): pass class UnimplementedFileMode(HTTPException): pass class IncompleteRead(HTTPException): def __init__(self, partial): self.partial = partial class ImproperConnectionState(HTTPException): pass class CannotSendRequest(ImproperConnectionState): pass class CannotSendHeader(ImproperConnectionState): pass class ResponseNotReady(ImproperConnectionState): pass class BadStatusLine(HTTPException): def __init__(self, line): self.line = line # for backwards compatibility error = HTTPException # # snarfed from httplib.py for now... # def test(): """Test this module. The test consists of retrieving and displaying the Python home page, along with the error code and error string returned by the www.python.org server. """ import sys import getopt opts, args = getopt.getopt(sys.argv[1:], 'd') dl = 0 for o, a in opts: if o == '-d': dl = dl + 1 host = 'www.python.org' selector = '/' if args[0:]: host = args[0] if args[1:]: selector = args[1] h = HTTP() h.set_debuglevel(dl) h.connect(host) h.putrequest('GET', selector) h.endheaders() status, reason, headers = h.getreply() print 'status =', status print 'reason =', reason print if headers: for header in headers.headers: print header.strip() print print h.getfile().read() if hasattr(socket, 'ssl'): host = 'sourceforge.net' selector = '/projects/python' hs = HTTPS() hs.connect(host) hs.putrequest('GET', selector) hs.endheaders() status, reason, headers = hs.getreply() print 'status =', status print 'reason =', reason print if headers: for header in headers.headers: print header.strip() print print hs.getfile().read() if __name__ == '__main__': test()