root / lib / http / server.py @ aea0ed67
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# Copyright (C) 2007, 2008 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""HTTP server module.
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"""
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import BaseHTTPServer |
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import cgi |
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import logging |
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import os |
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import select |
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import socket |
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import time |
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import signal |
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from ganeti import constants |
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from ganeti import serializer |
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from ganeti import utils |
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from ganeti import http |
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WEEKDAYNAME = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'] |
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MONTHNAME = [None,
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'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', |
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'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'] |
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# Default error message
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DEFAULT_ERROR_CONTENT_TYPE = "text/html"
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DEFAULT_ERROR_MESSAGE = """\
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<html>
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<head>
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<title>Error response</title>
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</head>
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<body>
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<h1>Error response</h1>
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<p>Error code %(code)d.
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<p>Message: %(message)s.
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<p>Error code explanation: %(code)s = %(explain)s.
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</body>
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</html>
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"""
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def _DateTimeHeader(gmnow=None): |
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"""Return the current date and time formatted for a message header.
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The time MUST be in the GMT timezone.
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"""
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if gmnow is None: |
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gmnow = time.gmtime() |
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(year, month, day, hh, mm, ss, wd, _, _) = gmnow |
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return ("%s, %02d %3s %4d %02d:%02d:%02d GMT" % |
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(WEEKDAYNAME[wd], day, MONTHNAME[month], year, hh, mm, ss)) |
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class _HttpServerRequest(object): |
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"""Data structure for HTTP request on server side.
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"""
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def __init__(self, request_msg): |
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# Request attributes
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self.request_method = request_msg.start_line.method
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self.request_path = request_msg.start_line.path
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self.request_headers = request_msg.headers
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self.request_body = request_msg.decoded_body
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# Response attributes
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self.resp_headers = {}
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class _HttpServerToClientMessageWriter(http.HttpMessageWriter): |
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"""Writes an HTTP response to client.
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"""
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def __init__(self, sock, request_msg, response_msg, write_timeout): |
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"""Writes the response to the client.
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@type sock: socket
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@param sock: Target socket
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@type request_msg: http.HttpMessage
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@param request_msg: Request message, required to determine whether
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response may have a message body
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@type response_msg: http.HttpMessage
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@param response_msg: Response message
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@type write_timeout: float
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@param write_timeout: Write timeout for socket
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"""
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self._request_msg = request_msg
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self._response_msg = response_msg
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http.HttpMessageWriter.__init__(self, sock, response_msg, write_timeout)
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def HasMessageBody(self): |
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"""Logic to detect whether response should contain a message body.
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"""
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if self._request_msg.start_line: |
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request_method = self._request_msg.start_line.method
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else:
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request_method = None
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response_code = self._response_msg.start_line.code
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# RFC2616, section 4.3: "A message-body MUST NOT be included in a request
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# if the specification of the request method (section 5.1.1) does not allow
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# sending an entity-body in requests"
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#
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# RFC2616, section 9.4: "The HEAD method is identical to GET except that
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# the server MUST NOT return a message-body in the response."
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#
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# RFC2616, section 10.2.5: "The 204 response MUST NOT include a
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# message-body [...]"
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#
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# RFC2616, section 10.3.5: "The 304 response MUST NOT contain a
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# message-body, [...]"
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return (http.HttpMessageWriter.HasMessageBody(self) and |
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(request_method is not None and |
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request_method != http.HTTP_HEAD) and
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response_code >= http.HTTP_OK and
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response_code not in (http.HTTP_NO_CONTENT, |
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http.HTTP_NOT_MODIFIED)) |
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class _HttpClientToServerMessageReader(http.HttpMessageReader): |
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"""Reads an HTTP request sent by client.
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"""
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# Length limits
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START_LINE_LENGTH_MAX = 4096
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HEADER_LENGTH_MAX = 4096
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def ParseStartLine(self, start_line): |
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"""Parses the start line sent by client.
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Example: "GET /index.html HTTP/1.1"
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@type start_line: string
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@param start_line: Start line
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"""
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# Empty lines are skipped when reading
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assert start_line
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logging.debug("HTTP request: %s", start_line)
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words = start_line.split() |
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if len(words) == 3: |
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[method, path, version] = words |
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if version[:5] != 'HTTP/': |
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raise http.HttpBadRequest("Bad request version (%r)" % version) |
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try:
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base_version_number = version.split("/", 1)[1] |
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version_number = base_version_number.split(".")
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# RFC 2145 section 3.1 says there can be only one "." and
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# - major and minor numbers MUST be treated as
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# separate integers;
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# - HTTP/2.4 is a lower version than HTTP/2.13, which in
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# turn is lower than HTTP/12.3;
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# - Leading zeros MUST be ignored by recipients.
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if len(version_number) != 2: |
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raise http.HttpBadRequest("Bad request version (%r)" % version) |
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version_number = (int(version_number[0]), int(version_number[1])) |
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except (ValueError, IndexError): |
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raise http.HttpBadRequest("Bad request version (%r)" % version) |
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if version_number >= (2, 0): |
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raise http.HttpVersionNotSupported("Invalid HTTP Version (%s)" % |
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base_version_number) |
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elif len(words) == 2: |
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version = http.HTTP_0_9 |
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[method, path] = words |
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if method != http.HTTP_GET:
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raise http.HttpBadRequest("Bad HTTP/0.9 request type (%r)" % method) |
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else:
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raise http.HttpBadRequest("Bad request syntax (%r)" % start_line) |
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return http.HttpClientToServerStartLine(method, path, version)
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class _HttpServerRequestExecutor(object): |
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"""Implements server side of HTTP.
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This class implements the server side of HTTP. It's based on code of Python's
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BaseHTTPServer, from both version 2.4 and 3k. It does not support non-ASCII
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character encodings. Keep-alive connections are not supported.
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"""
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# The default request version. This only affects responses up until
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# the point where the request line is parsed, so it mainly decides what
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# the client gets back when sending a malformed request line.
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# Most web servers default to HTTP 0.9, i.e. don't send a status line.
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default_request_version = http.HTTP_0_9 |
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# Error message settings
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error_message_format = DEFAULT_ERROR_MESSAGE |
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error_content_type = DEFAULT_ERROR_CONTENT_TYPE |
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responses = BaseHTTPServer.BaseHTTPRequestHandler.responses |
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# Timeouts in seconds for socket layer
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WRITE_TIMEOUT = 10
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READ_TIMEOUT = 10
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CLOSE_TIMEOUT = 1
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def __init__(self, server, sock, client_addr): |
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"""Initializes this class.
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"""
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self.server = server
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self.sock = sock
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self.client_addr = client_addr
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self.request_msg = http.HttpMessage()
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self.response_msg = http.HttpMessage()
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self.response_msg.start_line = \
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http.HttpServerToClientStartLine(version=self.default_request_version,
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code=None, reason=None) |
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# Disable Python's timeout
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self.sock.settimeout(None) |
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# Operate in non-blocking mode
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self.sock.setblocking(0) |
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logging.info("Connection from %s:%s", client_addr[0], client_addr[1]) |
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try:
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request_msg_reader = None
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force_close = True
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try:
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# Do the secret SSL handshake
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if self.server.using_ssl: |
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self.sock.set_accept_state()
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try:
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http.Handshake(self.sock, self.WRITE_TIMEOUT) |
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except http.HttpSessionHandshakeUnexpectedEOF:
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# Ignore rest
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return
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try:
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try:
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request_msg_reader = self._ReadRequest()
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self._HandleRequest()
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# Only wait for client to close if we didn't have any exception.
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force_close = False
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except http.HttpException, err:
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self._SetErrorStatus(err)
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finally:
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# Try to send a response
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self._SendResponse()
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finally:
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http.ShutdownConnection(sock, self.CLOSE_TIMEOUT, self.WRITE_TIMEOUT, |
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request_msg_reader, force_close) |
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self.sock.close()
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self.sock = None |
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finally:
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logging.info("Disconnected %s:%s", client_addr[0], client_addr[1]) |
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def _ReadRequest(self): |
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"""Reads a request sent by client.
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"""
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try:
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request_msg_reader = \ |
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_HttpClientToServerMessageReader(self.sock, self.request_msg, |
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self.READ_TIMEOUT)
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except http.HttpSocketTimeout:
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raise http.HttpError("Timeout while reading request") |
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except socket.error, err:
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raise http.HttpError("Error reading request: %s" % err) |
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self.response_msg.start_line.version = self.request_msg.start_line.version |
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return request_msg_reader
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def _HandleRequest(self): |
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"""Calls the handler function for the current request.
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"""
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handler_context = _HttpServerRequest(self.request_msg)
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try:
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result = self.server.HandleRequest(handler_context)
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except (http.HttpException, KeyboardInterrupt, SystemExit): |
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raise
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except Exception, err: |
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logging.exception("Caught exception")
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raise http.HttpInternalServerError(message=str(err)) |
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except:
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logging.exception("Unknown exception")
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raise http.HttpInternalServerError(message="Unknown error") |
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# TODO: Content-type
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encoder = http.HttpJsonConverter() |
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self.response_msg.start_line.code = http.HTTP_OK
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self.response_msg.body = encoder.Encode(result)
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self.response_msg.headers = handler_context.resp_headers
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self.response_msg.headers[http.HTTP_CONTENT_TYPE] = encoder.CONTENT_TYPE
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def _SendResponse(self): |
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"""Sends the response to the client.
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"""
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if self.response_msg.start_line.code is None: |
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return
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if not self.response_msg.headers: |
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self.response_msg.headers = {}
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self.response_msg.headers.update({
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# TODO: Keep-alive is not supported
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http.HTTP_CONNECTION: "close",
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http.HTTP_DATE: _DateTimeHeader(), |
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http.HTTP_SERVER: http.HTTP_GANETI_VERSION, |
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}) |
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# Get response reason based on code
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response_code = self.response_msg.start_line.code
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if response_code in self.responses: |
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response_reason = self.responses[response_code][0] |
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else:
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response_reason = ""
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self.response_msg.start_line.reason = response_reason
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logging.info("%s:%s %s %s", self.client_addr[0], self.client_addr[1], |
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self.request_msg.start_line, response_code)
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try:
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_HttpServerToClientMessageWriter(self.sock, self.request_msg, |
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self.response_msg, self.WRITE_TIMEOUT) |
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except http.HttpSocketTimeout:
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raise http.HttpError("Timeout while sending response") |
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except socket.error, err:
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raise http.HttpError("Error sending response: %s" % err) |
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def _SetErrorStatus(self, err): |
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"""Sets the response code and body from a HttpException.
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@type err: HttpException
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@param err: Exception instance
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"""
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try:
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(shortmsg, longmsg) = self.responses[err.code]
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except KeyError: |
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shortmsg = longmsg = "Unknown"
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if err.message:
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message = err.message |
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else:
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message = shortmsg |
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values = { |
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"code": err.code,
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"message": cgi.escape(message),
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"explain": longmsg,
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} |
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self.response_msg.start_line.code = err.code
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headers = {} |
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if err.headers:
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headers.update(err.headers) |
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headers[http.HTTP_CONTENT_TYPE] = self.error_content_type
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self.response_msg.headers = headers
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self.response_msg.body = self.error_message_format % values |
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class HttpServer(http.HttpBase): |
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"""Generic HTTP server class
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Users of this class must subclass it and override the HandleRequest function.
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"""
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MAX_CHILDREN = 20
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def __init__(self, mainloop, local_address, port, |
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ssl_params=None, ssl_verify_peer=False): |
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"""Initializes the HTTP server
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@type mainloop: ganeti.daemon.Mainloop
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@param mainloop: Mainloop used to poll for I/O events
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@type local_address: string
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@param local_address: Local IP address to bind to
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@type port: int
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@param port: TCP port to listen on
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@type ssl_params: HttpSslParams
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@param ssl_params: SSL key and certificate
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@type ssl_verify_peer: bool
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@param ssl_verify_peer: Whether to require client certificate and compare
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it with our certificate
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"""
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http.HttpBase.__init__(self)
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self.mainloop = mainloop
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self.local_address = local_address
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self.port = port
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self.socket = self._CreateSocket(ssl_params, ssl_verify_peer) |
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# Allow port to be reused
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self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) |
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self._children = []
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mainloop.RegisterIO(self, self.socket.fileno(), select.POLLIN) |
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mainloop.RegisterSignal(self)
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def Start(self): |
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self.socket.bind((self.local_address, self.port)) |
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self.socket.listen(1024) |
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def Stop(self): |
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self.socket.close()
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def OnIO(self, fd, condition): |
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if condition & select.POLLIN:
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self._IncomingConnection()
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def OnSignal(self, signum): |
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if signum == signal.SIGCHLD:
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self._CollectChildren(True) |
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def _CollectChildren(self, quick): |
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"""Checks whether any child processes are done
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@type quick: bool
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@param quick: Whether to only use non-blocking functions
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"""
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if not quick: |
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# Don't wait for other processes if it should be a quick check
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while len(self._children) > self.MAX_CHILDREN: |
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try:
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# Waiting without a timeout brings us into a potential DoS situation.
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# As soon as too many children run, we'll not respond to new
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# requests. The real solution would be to add a timeout for children
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# and killing them after some time.
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pid, status = os.waitpid(0, 0) |
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except os.error:
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pid = None
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if pid and pid in self._children: |
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self._children.remove(pid)
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for child in self._children: |
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try:
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pid, status = os.waitpid(child, os.WNOHANG) |
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except os.error:
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pid = None
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if pid and pid in self._children: |
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self._children.remove(pid)
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def _IncomingConnection(self): |
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"""Called for each incoming connection
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"""
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(connection, client_addr) = self.socket.accept()
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self._CollectChildren(False) |
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pid = os.fork() |
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if pid == 0: |
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# Child process
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try:
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_HttpServerRequestExecutor(self, connection, client_addr)
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except Exception: |
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logging.exception("Error while handling request from %s:%s",
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client_addr[0], client_addr[1]) |
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os._exit(1)
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os._exit(0)
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else:
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self._children.append(pid)
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def HandleRequest(self, req): |
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"""Handles a request.
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Must be overriden by subclass.
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"""
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raise NotImplementedError() |