Note: BaseHTTPRequestHandler doesn't implement any HTTP request; see
SimpleHTTPRequestHandler for simple implementations of GET, HEAD and POST,
and CGIHTTPRequestHandler for CGI scripts.
It does, however, optionally implement HTTP/1.1 persistent connections,
Notes on CGIHTTPRequestHandler
------------------------------
This class implements GET and POST requests to cgi-bin scripts.
If the os.fork() function is not present (e.g. on Windows),
subprocess.Popen() is used as a fallback, with slightly altered semantics.
In all cases, the implementation is intentionally naive -- all
requests are executed synchronously.
SECURITY WARNING: DON'T USE THIS CODE UNLESS YOU ARE INSIDE A FIREWALL
-- it may execute arbitrary Python code or external programs.
Note that status code 200 is sent prior to execution of a CGI script, so
scripts cannot send other status codes such as 302 (redirect).
- log requests even later (to capture byte count)
- log user-agent header and other interesting goodies
- send error log to separate file
# HTTP Working Group T. Berners-Lee
# INTERNET-DRAFT R. T. Fielding
# <draft-ietf-http-v10-spec-00.txt> H. Frystyk Nielsen
# Expires September 8, 1995 March 8, 1995
# URL: http://www.ics.uci.edu/pub/ietf/http/draft-ietf-http-v10-spec-00.txt
# Network Working Group R. Fielding
# Request for Comments: 2616 et al
# Obsoletes: 2068 June 1999
# Category: Standards Track
# URL: http://www.faqs.org/rfcs/rfc2616.html
# Here's a quote from the NCSA httpd docs about log file format.
# | The logfile format is as follows. Each line consists of:
# | host rfc931 authuser [DD/Mon/YYYY:hh:mm:ss] "request" ddd bbbb
# | host: Either the DNS name or the IP number of the remote client
# | rfc931: Any information returned by identd for this person,
# | authuser: If user sent a userid for authentication, the user name,
# | Mon: Month (calendar name)
# | hh: hour (24-hour format, the machine's timezone)
# | request: The first line of the HTTP request as sent by the client.
# | ddd: the status code returned by the server, - if not available.
# | bbbb: the total number of bytes sent,
# | *not including the HTTP/1.0 header*, - if not available
# | You can determine the name of the file accessed through request.
# (Actually, the latter is only true if you know the server configuration
# at the time the request was made!)
"HTTPServer", "ThreadingHTTPServer", "BaseHTTPRequestHandler",
"SimpleHTTPRequestHandler", "CGIHTTPRequestHandler",
import socket # For gethostbyaddr()
from functools import partial
from http import HTTPStatus
# Default error message template
DEFAULT_ERROR_MESSAGE = """\
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<title>Error response</title>
<p>Error code: %(code)d</p>
<p>Message: %(message)s.</p>
<p>Error code explanation: %(code)s - %(explain)s.</p>
DEFAULT_ERROR_CONTENT_TYPE = "text/html;charset=utf-8"
class HTTPServer(socketserver.TCPServer):
allow_reuse_address = 1 # Seems to make sense in testing environment
"""Override server_bind to store the server name."""
socketserver.TCPServer.server_bind(self)
host, port = self.server_address[:2]
self.server_name = socket.getfqdn(host)
class ThreadingHTTPServer(socketserver.ThreadingMixIn, HTTPServer):
class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
"""HTTP request handler base class.
The following explanation of HTTP serves to guide you through the
code as well as to expose any misunderstandings I may have about
HTTP (so you don't need to read the code to figure out I'm wrong
HTTP (HyperText Transfer Protocol) is an extensible protocol on
top of a reliable stream transport (e.g. TCP/IP). The protocol
recognizes three parts to a request:
1. One line identifying the request type and path
2. An optional set of RFC-822-style headers
The headers and data are separated by a blank line.
The first line of the request has the form
<command> <path> <version>
where <command> is a (case-sensitive) keyword such as GET or POST,
<path> is a string containing path information for the request,
and <version> should be the string "HTTP/1.0" or "HTTP/1.1".
<path> is encoded using the URL encoding scheme (using %xx to signify
the ASCII character with hex code xx).
The specification specifies that lines are separated by CRLF but
for compatibility with the widest range of clients recommends
servers also handle LF. Similarly, whitespace in the request line
is treated sensibly (allowing multiple spaces between components
and allowing trailing whitespace).
Similarly, for output, lines ought to be separated by CRLF pairs
but most clients grok LF characters just fine.
If the first line of the request has the form
(i.e. <version> is left out) then this is assumed to be an HTTP
0.9 request; this form has no optional headers and data part and
the reply consists of just the data.
The reply form of the HTTP 1.x protocol again has three parts:
1. One line giving the response code
2. An optional set of RFC-822-style headers
Again, the headers and data are separated by a blank line.
The response code line has the form
<version> <responsecode> <responsestring>
where <version> is the protocol version ("HTTP/1.0" or "HTTP/1.1"),
<responsecode> is a 3-digit response code indicating success or
failure of the request, and <responsestring> is an optional
human-readable string explaining what the response code means.
This server parses the request and the headers, and then calls a
function specific to the request type (<command>). Specifically,
a request SPAM will be handled by a method do_SPAM(). If no
such method exists the server sends an error response to the
client. If it exists, it is called with no arguments:
Note that the request name is case sensitive (i.e. SPAM and spam
The various request details are stored in instance variables:
- client_address is the client IP address in the form (host,
- command, path and version are the broken-down request line;
- headers is an instance of email.message.Message (or a derived
class) containing the header information;
- rfile is a file object open for reading positioned at the
start of the optional input data part;
- wfile is a file object open for writing.
IT IS IMPORTANT TO ADHERE TO THE PROTOCOL FOR WRITING!
The first thing to be written must be the response line. Then
follow 0 or more header lines, then a blank line, and then the
actual data (if any). The meaning of the header lines depends on
the command executed by the server; in most cases, when data is
returned, there should be at least one header line of the form
Content-type: <type>/<subtype>
where <type> and <subtype> should be registered MIME types,
e.g. "text/html" or "text/plain".
# The Python system version, truncated to its first component.
sys_version = "Python/" + sys.version.split()[0]
# The server software version. You may want to override this.
# The format is multiple whitespace-separated strings,
# where each string is of the form name[/version].
server_version = "BaseHTTP/" + __version__
error_message_format = DEFAULT_ERROR_MESSAGE
error_content_type = DEFAULT_ERROR_CONTENT_TYPE
# 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/0.9"
"""Parse a request (internal).
The request should be stored in self.raw_requestline; the results
are in self.command, self.path, self.request_version and
Return True for success, False for failure; on failure, any relevant
error response has already been sent back.
self.command = None # set in case of error on the first line
self.request_version = version = self.default_request_version
self.close_connection = True
requestline = str(self.raw_requestline, 'iso-8859-1')
requestline = requestline.rstrip('\r\n')
self.requestline = requestline
words = requestline.split()
if len(words) >= 3: # Enough to determine protocol version
if not version.startswith('HTTP/'):
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
# - 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:
version_number = int(version_number[0]), int(version_number[1])
except (ValueError, IndexError):
"Bad request version (%r)" % version)
if version_number >= (1, 1) and self.protocol_version >= "HTTP/1.1":
self.close_connection = False
if version_number >= (2, 0):
HTTPStatus.HTTP_VERSION_NOT_SUPPORTED,
"Invalid HTTP version (%s)" % base_version_number)
self.request_version = version
if not 2 <= len(words) <= 3:
"Bad request syntax (%r)" % requestline)
command, path = words[:2]
self.close_connection = True
"Bad HTTP/0.9 request type (%r)" % command)
self.command, self.path = command, path
# gh-87389: The purpose of replacing '//' with '/' is to protect
# against open redirect attacks possibly triggered if the path starts
# with '//' because http clients treat //path as an absolute URI
# without scheme (similar to http://path) rather than a path.
if self.path.startswith('//'):
self.path = '/' + self.path.lstrip('/') # Reduce to a single /
# Examine the headers and look for a Connection directive.
self.headers = http.client.parse_headers(self.rfile,
_class=self.MessageClass)
except http.client.LineTooLong as err:
HTTPStatus.REQUEST_HEADER_FIELDS_TOO_LARGE,
except http.client.HTTPException as err:
HTTPStatus.REQUEST_HEADER_FIELDS_TOO_LARGE,
conntype = self.headers.get('Connection', "")
if conntype.lower() == 'close':
self.close_connection = True
elif (conntype.lower() == 'keep-alive' and
self.protocol_version >= "HTTP/1.1"):
self.close_connection = False
# Examine the headers and look for an Expect directive
expect = self.headers.get('Expect', "")
if (expect.lower() == "100-continue" and
self.protocol_version >= "HTTP/1.1" and
self.request_version >= "HTTP/1.1"):
if not self.handle_expect_100():
def handle_expect_100(self):
"""Decide what to do with an "Expect: 100-continue" header.
If the client is expecting a 100 Continue response, we must
respond with either a 100 Continue or a final response before
waiting for the request body. The default is to always respond
with a 100 Continue. You can behave differently (for example,
reject unauthorized requests) by overriding this method.
This method should either return True (possibly after sending
a 100 Continue response) or send an error response and return
self.send_response_only(HTTPStatus.CONTINUE)
def handle_one_request(self):
"""Handle a single HTTP request.
You normally don't need to override this method; see the class
__doc__ string for information on how to handle specific HTTP
commands such as GET and POST.
self.raw_requestline = self.rfile.readline(65537)
if len(self.raw_requestline) > 65536:
self.request_version = ''
self.send_error(HTTPStatus.REQUEST_URI_TOO_LONG)
if not self.raw_requestline:
self.close_connection = True
if not self.parse_request():
# An error code has been sent, just exit
mname = 'do_' + self.command
if not hasattr(self, mname):
HTTPStatus.NOT_IMPLEMENTED,
"Unsupported method (%r)" % self.command)
method = getattr(self, mname)
self.wfile.flush() #actually send the response if not already done.
except socket.timeout as e:
#a read or a write timed out. Discard this connection
self.log_error("Request timed out: %r", e)
self.close_connection = True
"""Handle multiple requests if necessary."""
self.close_connection = True
self.handle_one_request()
while not self.close_connection:
self.handle_one_request()
def send_error(self, code, message=None, explain=None):
"""Send and log an error reply.
* code: an HTTP error code
* message: a simple optional 1 line reason phrase.
*( HTAB / SP / VCHAR / %x80-FF )
defaults to short entry matching the response code
* explain: a detailed message defaults to the long entry
matching the response code.
This sends an error response (so it must be called before any
output has been generated), logs the error, and finally sends
a piece of HTML explaining the error to the user.
shortmsg, longmsg = self.responses[code]
shortmsg, longmsg = '???', '???'
self.log_error("code %d, message %s", code, message)
self.send_response(code, message)
self.send_header('Connection', 'close')
# Message body is omitted for cases described in:
# - RFC7230: 3.3. 1xx, 204(No Content), 304(Not Modified)
# - RFC7231: 6.3.6. 205(Reset Content)
code not in (HTTPStatus.NO_CONTENT,
HTTPStatus.RESET_CONTENT,
HTTPStatus.NOT_MODIFIED)):
# HTML encode to prevent Cross Site Scripting attacks
content = (self.error_message_format % {
'message': html.escape(message, quote=False),
'explain': html.escape(explain, quote=False)
body = content.encode('UTF-8', 'replace')
self.send_header("Content-Type", self.error_content_type)
self.send_header('Content-Length', str(len(body)))
if self.command != 'HEAD' and body:
def send_response(self, code, message=None):
"""Add the response header to the headers buffer and log the
Also send two standard headers with the server software
version and the current date.
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
