# # # Copyright (C) 2007, 2008 Google Inc. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA # 02110-1301, USA. """HTTP server module. """ import BaseHTTPServer import cgi import logging import os import select import socket import time import signal import asyncore from ganeti import http WEEKDAYNAME = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'] MONTHNAME = [None, 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'] # Default error message DEFAULT_ERROR_CONTENT_TYPE = "text/html" DEFAULT_ERROR_MESSAGE = """\ Error response

Error response

Error code %(code)d.

Message: %(message)s.

Error code explanation: %(code)s = %(explain)s. """ def _DateTimeHeader(gmnow=None): """Return the current date and time formatted for a message header. The time MUST be in the GMT timezone. """ if gmnow is None: gmnow = time.gmtime() (year, month, day, hh, mm, ss, wd, _, _) = gmnow return ("%s, %02d %3s %4d %02d:%02d:%02d GMT" % (WEEKDAYNAME[wd], day, MONTHNAME[month], year, hh, mm, ss)) class _HttpServerRequest(object): """Data structure for HTTP request on server side. """ def __init__(self, request_msg): # Request attributes self.request_method = request_msg.start_line.method self.request_path = request_msg.start_line.path self.request_headers = request_msg.headers self.request_body = request_msg.decoded_body # Response attributes self.resp_headers = {} # Private data for request handler (useful in combination with # authentication) self.private = None class _HttpServerToClientMessageWriter(http.HttpMessageWriter): """Writes an HTTP response to client. """ def __init__(self, sock, request_msg, response_msg, write_timeout): """Writes the response to the client. @type sock: socket @param sock: Target socket @type request_msg: http.HttpMessage @param request_msg: Request message, required to determine whether response may have a message body @type response_msg: http.HttpMessage @param response_msg: Response message @type write_timeout: float @param write_timeout: Write timeout for socket """ self._request_msg = request_msg self._response_msg = response_msg http.HttpMessageWriter.__init__(self, sock, response_msg, write_timeout) def HasMessageBody(self): """Logic to detect whether response should contain a message body. """ if self._request_msg.start_line: request_method = self._request_msg.start_line.method else: request_method = None response_code = self._response_msg.start_line.code # RFC2616, section 4.3: "A message-body MUST NOT be included in a request # if the specification of the request method (section 5.1.1) does not allow # sending an entity-body in requests" # # RFC2616, section 9.4: "The HEAD method is identical to GET except that # the server MUST NOT return a message-body in the response." # # RFC2616, section 10.2.5: "The 204 response MUST NOT include a # message-body [...]" # # RFC2616, section 10.3.5: "The 304 response MUST NOT contain a # message-body, [...]" return (http.HttpMessageWriter.HasMessageBody(self) and (request_method is not None and request_method != http.HTTP_HEAD) and response_code >= http.HTTP_OK and response_code not in (http.HTTP_NO_CONTENT, http.HTTP_NOT_MODIFIED)) class _HttpClientToServerMessageReader(http.HttpMessageReader): """Reads an HTTP request sent by client. """ # Length limits START_LINE_LENGTH_MAX = 4096 HEADER_LENGTH_MAX = 4096 def ParseStartLine(self, start_line): """Parses the start line sent by client. Example: "GET /index.html HTTP/1.1" @type start_line: string @param start_line: Start line """ # Empty lines are skipped when reading assert start_line logging.debug("HTTP request: %s", start_line) words = start_line.split() if len(words) == 3: [method, path, version] = words if version[:5] != 'HTTP/': raise http.HttpBadRequest("Bad request version (%r)" % version) try: base_version_number = version.split("/", 1)[1] version_number = base_version_number.split(".") # RFC 2145 section 3.1 says there can be only one "." and # - major and minor numbers MUST be treated as # separate integers; # - HTTP/2.4 is a lower version than HTTP/2.13, which in # turn is lower than HTTP/12.3; # - Leading zeros MUST be ignored by recipients. if len(version_number) != 2: raise http.HttpBadRequest("Bad request version (%r)" % version) version_number = (int(version_number[0]), int(version_number[1])) except (ValueError, IndexError): raise http.HttpBadRequest("Bad request version (%r)" % version) if version_number >= (2, 0): raise http.HttpVersionNotSupported("Invalid HTTP Version (%s)" % base_version_number) elif len(words) == 2: version = http.HTTP_0_9 [method, path] = words if method != http.HTTP_GET: raise http.HttpBadRequest("Bad HTTP/0.9 request type (%r)" % method) else: raise http.HttpBadRequest("Bad request syntax (%r)" % start_line) return http.HttpClientToServerStartLine(method, path, version) class HttpServerRequestExecutor(object): """Implements server side of HTTP. This class implements the server side of HTTP. It's based on code of Python's BaseHTTPServer, from both version 2.4 and 3k. It does not support non-ASCII character encodings. Keep-alive connections are not supported. """ # The default request version. This only affects responses up until # the point where the request line is parsed, so it mainly decides what # the client gets back when sending a malformed request line. # Most web servers default to HTTP 0.9, i.e. don't send a status line. default_request_version = http.HTTP_0_9 # Error message settings error_message_format = DEFAULT_ERROR_MESSAGE error_content_type = DEFAULT_ERROR_CONTENT_TYPE responses = BaseHTTPServer.BaseHTTPRequestHandler.responses # Timeouts in seconds for socket layer WRITE_TIMEOUT = 10 READ_TIMEOUT = 10 CLOSE_TIMEOUT = 1 def __init__(self, server, sock, client_addr): """Initializes this class. """ self.server = server self.sock = sock self.client_addr = client_addr self.request_msg = http.HttpMessage() self.response_msg = http.HttpMessage() self.response_msg.start_line = \ http.HttpServerToClientStartLine(version=self.default_request_version, code=None, reason=None) # Disable Python's timeout self.sock.settimeout(None) # Operate in non-blocking mode self.sock.setblocking(0) logging.debug("Connection from %s:%s", client_addr[0], client_addr[1]) try: request_msg_reader = None force_close = True try: # Do the secret SSL handshake if self.server.using_ssl: self.sock.set_accept_state() try: http.Handshake(self.sock, self.WRITE_TIMEOUT) except http.HttpSessionHandshakeUnexpectedEOF: # Ignore rest return try: try: request_msg_reader = self._ReadRequest() self._HandleRequest() # Only wait for client to close if we didn't have any exception. force_close = False except http.HttpException, err: self._SetErrorStatus(err) finally: # Try to send a response self._SendResponse() finally: http.ShutdownConnection(sock, self.CLOSE_TIMEOUT, self.WRITE_TIMEOUT, request_msg_reader, force_close) self.sock.close() self.sock = None finally: logging.debug("Disconnected %s:%s", client_addr[0], client_addr[1]) def _ReadRequest(self): """Reads a request sent by client. """ try: request_msg_reader = \ _HttpClientToServerMessageReader(self.sock, self.request_msg, self.READ_TIMEOUT) except http.HttpSocketTimeout: raise http.HttpError("Timeout while reading request") except socket.error, err: raise http.HttpError("Error reading request: %s" % err) self.response_msg.start_line.version = self.request_msg.start_line.version return request_msg_reader def _HandleRequest(self): """Calls the handler function for the current request. """ handler_context = _HttpServerRequest(self.request_msg) try: try: # Authentication, etc. self.server.PreHandleRequest(handler_context) # Call actual request handler result = self.server.HandleRequest(handler_context) except (http.HttpException, KeyboardInterrupt, SystemExit): raise except Exception, err: logging.exception("Caught exception") raise http.HttpInternalServerError(message=str(err)) except: logging.exception("Unknown exception") raise http.HttpInternalServerError(message="Unknown error") # TODO: Content-type encoder = http.HttpJsonConverter() self.response_msg.start_line.code = http.HTTP_OK self.response_msg.body = encoder.Encode(result) self.response_msg.headers = handler_context.resp_headers self.response_msg.headers[http.HTTP_CONTENT_TYPE] = encoder.CONTENT_TYPE finally: # No reason to keep this any longer, even for exceptions handler_context.private = None def _SendResponse(self): """Sends the response to the client. """ if self.response_msg.start_line.code is None: return if not self.response_msg.headers: self.response_msg.headers = {} self.response_msg.headers.update({ # TODO: Keep-alive is not supported http.HTTP_CONNECTION: "close", http.HTTP_DATE: _DateTimeHeader(), http.HTTP_SERVER: http.HTTP_GANETI_VERSION, }) # Get response reason based on code response_code = self.response_msg.start_line.code if response_code in self.responses: response_reason = self.responses[response_code][0] else: response_reason = "" self.response_msg.start_line.reason = response_reason logging.info("%s:%s %s %s", self.client_addr[0], self.client_addr[1], self.request_msg.start_line, response_code) try: _HttpServerToClientMessageWriter(self.sock, self.request_msg, self.response_msg, self.WRITE_TIMEOUT) except http.HttpSocketTimeout: raise http.HttpError("Timeout while sending response") except socket.error, err: raise http.HttpError("Error sending response: %s" % err) def _SetErrorStatus(self, err): """Sets the response code and body from a HttpException. @type err: HttpException @param err: Exception instance """ try: (shortmsg, longmsg) = self.responses[err.code] except KeyError: shortmsg = longmsg = "Unknown" if err.message: message = err.message else: message = shortmsg values = { "code": err.code, "message": cgi.escape(message), "explain": longmsg, } self.response_msg.start_line.code = err.code headers = {} if err.headers: headers.update(err.headers) headers[http.HTTP_CONTENT_TYPE] = self.error_content_type self.response_msg.headers = headers self.response_msg.body = self._FormatErrorMessage(values) def _FormatErrorMessage(self, values): """Formats the body of an error message. @type values: dict @param values: dictionary with keys code, message and explain. @rtype: string @return: the body of the message """ return self.error_message_format % values class HttpServer(http.HttpBase, asyncore.dispatcher): """Generic HTTP server class Users of this class must subclass it and override the HandleRequest function. """ MAX_CHILDREN = 20 def __init__(self, mainloop, local_address, port, ssl_params=None, ssl_verify_peer=False, request_executor_class=None): """Initializes the HTTP server @type mainloop: ganeti.daemon.Mainloop @param mainloop: Mainloop used to poll for I/O events @type local_address: string @param local_address: Local IP address to bind to @type port: int @param port: TCP port to listen on @type ssl_params: HttpSslParams @param ssl_params: SSL key and certificate @type ssl_verify_peer: bool @param ssl_verify_peer: Whether to require client certificate and compare it with our certificate @type request_executor_class: class @param request_executor_class: an class derived from the HttpServerRequestExecutor class """ http.HttpBase.__init__(self) asyncore.dispatcher.__init__(self) if request_executor_class is None: self.request_executor = HttpServerRequestExecutor else: self.request_executor = request_executor_class self.mainloop = mainloop self.local_address = local_address self.port = port self.socket = self._CreateSocket(ssl_params, ssl_verify_peer) # Allow port to be reused self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self._children = [] self.set_socket(self.socket) self.accepting = True mainloop.RegisterSignal(self) def Start(self): self.socket.bind((self.local_address, self.port)) self.socket.listen(1024) def Stop(self): self.socket.close() def handle_accept(self): self._IncomingConnection() def OnSignal(self, signum): if signum == signal.SIGCHLD: self._CollectChildren(True) def _CollectChildren(self, quick): """Checks whether any child processes are done @type quick: bool @param quick: Whether to only use non-blocking functions """ if not quick: # Don't wait for other processes if it should be a quick check while len(self._children) > self.MAX_CHILDREN: try: # Waiting without a timeout brings us into a potential DoS situation. # As soon as too many children run, we'll not respond to new # requests. The real solution would be to add a timeout for children # and killing them after some time. pid, _ = os.waitpid(0, 0) except os.error: pid = None if pid and pid in self._children: self._children.remove(pid) for child in self._children: try: pid, status = os.waitpid(child, os.WNOHANG) except os.error: pid = None if pid and pid in self._children: self._children.remove(pid) def _IncomingConnection(self): """Called for each incoming connection """ (connection, client_addr) = self.socket.accept() self._CollectChildren(False) pid = os.fork() if pid == 0: # Child process try: self.request_executor(self, connection, client_addr) except Exception: logging.exception("Error while handling request from %s:%s", client_addr[0], client_addr[1]) os._exit(1) os._exit(0) else: self._children.append(pid) def PreHandleRequest(self, req): """Called before handling a request. Can be overridden by a subclass. """ def HandleRequest(self, req): """Handles a request. Must be overridden by subclass. """ raise NotImplementedError()