503 lines
17 KiB
Python
Executable File
503 lines
17 KiB
Python
Executable File
"""HTTP server base class.
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Note: the class in this module doesn't implement any HTTP request; see
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SimpleHTTPServer for simple implementations of GET, HEAD and POST
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(including CGI scripts).
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Contents:
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- BaseHTTPRequestHandler: HTTP request handler base class
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- test: test function
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XXX To do:
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- send server version
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- log requests even later (to capture byte count)
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- log user-agent header and other interesting goodies
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- send error log to separate file
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- are request names really case sensitive?
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"""
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# See also:
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#
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# HTTP Working Group T. Berners-Lee
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# INTERNET-DRAFT R. T. Fielding
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# <draft-ietf-http-v10-spec-00.txt> H. Frystyk Nielsen
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# Expires September 8, 1995 March 8, 1995
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#
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# URL: http://www.ics.uci.edu/pub/ietf/http/draft-ietf-http-v10-spec-00.txt
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# Log files
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# ---------
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#
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# Here's a quote from the NCSA httpd docs about log file format.
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#
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# | The logfile format is as follows. Each line consists of:
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# |
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# | host rfc931 authuser [DD/Mon/YYYY:hh:mm:ss] "request" ddd bbbb
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# |
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# | host: Either the DNS name or the IP number of the remote client
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# | rfc931: Any information returned by identd for this person,
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# | - otherwise.
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# | authuser: If user sent a userid for authentication, the user name,
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# | - otherwise.
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# | DD: Day
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# | Mon: Month (calendar name)
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# | YYYY: Year
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# | hh: hour (24-hour format, the machine's timezone)
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# | mm: minutes
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# | ss: seconds
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# | request: The first line of the HTTP request as sent by the client.
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# | ddd: the status code returned by the server, - if not available.
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# | bbbb: the total number of bytes sent,
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# | *not including the HTTP/1.0 header*, - if not available
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# |
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# | You can determine the name of the file accessed through request.
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#
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# (Actually, the latter is only true if you know the server configuration
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# at the time the request was made!)
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__version__ = "0.2"
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import sys
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import time
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import socket # For gethostbyaddr()
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import string
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import mimetools
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import SocketServer
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# Default error message
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DEFAULT_ERROR_MESSAGE = """\
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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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"""
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class HTTPServer(SocketServer.TCPServer):
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allow_reuse_address = 1 # Seems to make sense in testing environment
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def server_bind(self):
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"""Override server_bind to store the server name."""
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SocketServer.TCPServer.server_bind(self)
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host, port = self.socket.getsockname()
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if not host or host == '0.0.0.0':
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host = socket.gethostname()
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try:
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hostname, hostnames, hostaddrs = socket.gethostbyaddr(host)
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except socket.error:
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hostname = host
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else:
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if '.' not in hostname:
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for host in hostnames:
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if '.' in host:
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hostname = host
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break
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self.server_name = hostname
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self.server_port = port
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class BaseHTTPRequestHandler(SocketServer.StreamRequestHandler):
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"""HTTP request handler base class.
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The following explanation of HTTP serves to guide you through the
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code as well as to expose any misunderstandings I may have about
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HTTP (so you don't need to read the code to figure out I'm wrong
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:-).
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HTTP (HyperText Transfer Protocol) is an extensible protocol on
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top of a reliable stream transport (e.g. TCP/IP). The protocol
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recognizes three parts to a request:
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1. One line identifying the request type and path
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2. An optional set of RFC-822-style headers
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3. An optional data part
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The headers and data are separated by a blank line.
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The first line of the request has the form
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<command> <path> <version>
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where <command> is a (case-sensitive) keyword such as GET or POST,
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<path> is a string containing path information for the request,
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and <version> should be the string "HTTP/1.0". <path> is encoded
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using the URL encoding scheme (using %xx to signify the ASCII
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character with hex code xx).
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The protocol is vague about whether lines are separated by LF
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characters or by CRLF pairs -- for compatibility with the widest
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range of clients, both should be accepted. Similarly, whitespace
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in the request line should be treated sensibly (allowing multiple
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spaces between components and allowing trailing whitespace).
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Similarly, for output, lines ought to be separated by CRLF pairs
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but most clients grok LF characters just fine.
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If the first line of the request has the form
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<command> <path>
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(i.e. <version> is left out) then this is assumed to be an HTTP
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0.9 request; this form has no optional headers and data part and
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the reply consists of just the data.
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The reply form of the HTTP 1.0 protocol again has three parts:
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1. One line giving the response code
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2. An optional set of RFC-822-style headers
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3. The data
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Again, the headers and data are separated by a blank line.
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The response code line has the form
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<version> <responsecode> <responsestring>
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where <version> is the protocol version (always "HTTP/1.0"),
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<responsecode> is a 3-digit response code indicating success or
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failure of the request, and <responsestring> is an optional
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human-readable string explaining what the response code means.
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This server parses the request and the headers, and then calls a
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function specific to the request type (<command>). Specifically,
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a request SPAM will be handled by a method do_SPAM(). If no
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such method exists the server sends an error response to the
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client. If it exists, it is called with no arguments:
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do_SPAM()
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Note that the request name is case sensitive (i.e. SPAM and spam
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are different requests).
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The various request details are stored in instance variables:
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- client_address is the client IP address in the form (host,
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port);
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- command, path and version are the broken-down request line;
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- headers is an instance of mimetools.Message (or a derived
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class) containing the header information;
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- rfile is a file object open for reading positioned at the
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start of the optional input data part;
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- wfile is a file object open for writing.
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IT IS IMPORTANT TO ADHERE TO THE PROTOCOL FOR WRITING!
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The first thing to be written must be the response line. Then
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follow 0 or more header lines, then a blank line, and then the
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actual data (if any). The meaning of the header lines depends on
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the command executed by the server; in most cases, when data is
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returned, there should be at least one header line of the form
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Content-type: <type>/<subtype>
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where <type> and <subtype> should be registered MIME types,
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e.g. "text/html" or "text/plain".
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"""
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# The Python system version, truncated to its first component.
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sys_version = "Python/" + string.split(sys.version)[0]
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# The server software version. You may want to override this.
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# The format is multiple whitespace-separated strings,
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# where each string is of the form name[/version].
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server_version = "BaseHTTP/" + __version__
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def parse_request(self):
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"""Parse a request (internal).
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The request should be stored in self.raw_request; the results
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are in self.command, self.path, self.request_version and
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self.headers.
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Return value is 1 for success, 0 for failure; on failure, an
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error is sent back.
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"""
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self.request_version = version = "HTTP/0.9" # Default
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requestline = self.raw_requestline
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if requestline[-2:] == '\r\n':
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requestline = requestline[:-2]
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elif requestline[-1:] == '\n':
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requestline = requestline[:-1]
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self.requestline = requestline
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words = string.split(requestline)
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if len(words) == 3:
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[command, path, version] = words
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if version[:5] != 'HTTP/':
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self.send_error(400, "Bad request version (%s)" % `version`)
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return 0
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elif len(words) == 2:
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[command, path] = words
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if command != 'GET':
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self.send_error(400,
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"Bad HTTP/0.9 request type (%s)" % `command`)
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return 0
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else:
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self.send_error(400, "Bad request syntax (%s)" % `requestline`)
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return 0
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self.command, self.path, self.request_version = command, path, version
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self.headers = self.MessageClass(self.rfile, 0)
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return 1
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def handle(self):
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"""Handle a single HTTP request.
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You normally don't need to override this method; see the class
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__doc__ string for information on how to handle specific HTTP
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commands such as GET and POST.
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"""
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self.raw_requestline = self.rfile.readline()
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if not self.parse_request(): # An error code has been sent, just exit
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return
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mname = 'do_' + self.command
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if not hasattr(self, mname):
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self.send_error(501, "Unsupported method (%s)" % `self.command`)
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return
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method = getattr(self, mname)
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method()
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def send_error(self, code, message=None):
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"""Send and log an error reply.
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Arguments are the error code, and a detailed message.
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The detailed message defaults to the short entry matching the
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response code.
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This sends an error response (so it must be called before any
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output has been generated), logs the error, and finally sends
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a piece of HTML explaining the error to the user.
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"""
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try:
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short, long = self.responses[code]
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except KeyError:
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short, long = '???', '???'
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if not message:
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message = short
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explain = long
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self.log_error("code %d, message %s", code, message)
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self.send_response(code, message)
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self.end_headers()
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self.wfile.write(self.error_message_format %
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{'code': code,
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'message': message,
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'explain': explain})
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error_message_format = DEFAULT_ERROR_MESSAGE
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def send_response(self, code, message=None):
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"""Send the response header and log the response code.
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Also send two standard headers with the server software
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version and the current date.
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"""
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self.log_request(code)
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if message is None:
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if self.responses.has_key(code):
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message = self.responses[code][0]
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else:
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message = ''
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if self.request_version != 'HTTP/0.9':
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self.wfile.write("%s %s %s\r\n" %
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(self.protocol_version, str(code), message))
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self.send_header('Server', self.version_string())
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self.send_header('Date', self.date_time_string())
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def send_header(self, keyword, value):
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"""Send a MIME header."""
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if self.request_version != 'HTTP/0.9':
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self.wfile.write("%s: %s\r\n" % (keyword, value))
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def end_headers(self):
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"""Send the blank line ending the MIME headers."""
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if self.request_version != 'HTTP/0.9':
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self.wfile.write("\r\n")
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def log_request(self, code='-', size='-'):
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"""Log an accepted request.
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This is called by send_reponse().
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"""
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self.log_message('"%s" %s %s',
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self.requestline, str(code), str(size))
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def log_error(self, *args):
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"""Log an error.
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This is called when a request cannot be fulfilled. By
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default it passes the message on to log_message().
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Arguments are the same as for log_message().
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XXX This should go to the separate error log.
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"""
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apply(self.log_message, args)
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def log_message(self, format, *args):
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"""Log an arbitrary message.
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This is used by all other logging functions. Override
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it if you have specific logging wishes.
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The first argument, FORMAT, is a format string for the
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message to be logged. If the format string contains
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any % escapes requiring parameters, they should be
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specified as subsequent arguments (it's just like
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printf!).
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The client host and current date/time are prefixed to
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every message.
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"""
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sys.stderr.write("%s - - [%s] %s\n" %
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(self.address_string(),
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self.log_date_time_string(),
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format%args))
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def version_string(self):
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"""Return the server software version string."""
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return self.server_version + ' ' + self.sys_version
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def date_time_string(self):
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"""Return the current date and time formatted for a message header."""
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now = time.time()
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year, month, day, hh, mm, ss, wd, y, z = time.gmtime(now)
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s = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (
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self.weekdayname[wd],
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day, self.monthname[month], year,
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hh, mm, ss)
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return s
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def log_date_time_string(self):
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"""Return the current time formatted for logging."""
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now = time.time()
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year, month, day, hh, mm, ss, x, y, z = time.localtime(now)
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s = "%02d/%3s/%04d %02d:%02d:%02d" % (
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day, self.monthname[month], year, hh, mm, ss)
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return s
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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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def address_string(self):
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"""Return the client address formatted for logging.
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This version looks up the full hostname using gethostbyaddr(),
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and tries to find a name that contains at least one dot.
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"""
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(host, port) = self.client_address
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try:
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name, names, addresses = socket.gethostbyaddr(host)
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except socket.error, msg:
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return host
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names.insert(0, name)
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for name in names:
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if '.' in name: return name
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return names[0]
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# Essentially static class variables
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# The version of the HTTP protocol we support.
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# Don't override unless you know what you're doing (hint: incoming
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# requests are required to have exactly this version string).
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protocol_version = "HTTP/1.0"
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# The Message-like class used to parse headers
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MessageClass = mimetools.Message
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# Table mapping response codes to messages; entries have the
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# form {code: (shortmessage, longmessage)}.
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# See http://www.w3.org/hypertext/WWW/Protocols/HTTP/HTRESP.html
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responses = {
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200: ('OK', 'Request fulfilled, document follows'),
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201: ('Created', 'Document created, URL follows'),
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202: ('Accepted',
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'Request accepted, processing continues off-line'),
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203: ('Partial information', 'Request fulfilled from cache'),
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204: ('No response', 'Request fulfilled, nothing follows'),
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301: ('Moved', 'Object moved permanently -- see URI list'),
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302: ('Found', 'Object moved temporarily -- see URI list'),
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303: ('Method', 'Object moved -- see Method and URL list'),
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304: ('Not modified',
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'Document has not changed singe given time'),
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400: ('Bad request',
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'Bad request syntax or unsupported method'),
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401: ('Unauthorized',
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'No permission -- see authorization schemes'),
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402: ('Payment required',
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'No payment -- see charging schemes'),
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403: ('Forbidden',
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'Request forbidden -- authorization will not help'),
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404: ('Not found', 'Nothing matches the given URI'),
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500: ('Internal error', 'Server got itself in trouble'),
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501: ('Not implemented',
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'Server does not support this operation'),
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502: ('Service temporarily overloaded',
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'The server cannot process the request due to a high load'),
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503: ('Gateway timeout',
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'The gateway server did not receive a timely response'),
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}
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def test(HandlerClass = BaseHTTPRequestHandler,
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ServerClass = HTTPServer):
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"""Test the HTTP request handler class.
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This runs an HTTP server on port 8000 (or the first command line
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argument).
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"""
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if sys.argv[1:]:
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port = string.atoi(sys.argv[1])
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else:
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port = 8000
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server_address = ('', port)
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httpd = ServerClass(server_address, HandlerClass)
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print "Serving HTTP on port", port, "..."
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httpd.serve_forever()
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if __name__ == '__main__':
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test()
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