"""CGI-savvy HTTP Server.
This module builds on SimpleHTTPServer by implementing GET and POST
requests to cgi-bin scripts.
If the os.fork() function is not present (e.g. on Windows),
os.popen2() is used as a fallback, with slightly altered semantics; if
that function is not present either (e.g. on Macintosh), only Python
scripts are supported, and they are executed by the current process.
In all cases, the implementation is intentionally naive -- all
requests are executed sychronously.
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).
"""
__version__ = "0.4"
__all__ = ["CGIHTTPRequestHandler"]
import os
import sys
import urllib
import BaseHTTPServer
import SimpleHTTPServer
import select
import copy
class CGIHTTPRequestHandler(SimpleHTTPServer.SimpleHTTPRequestHandler):
"""Complete HTTP server with GET, HEAD and POST commands.
GET and HEAD also support running CGI scripts.
The POST command is *only* implemented for CGI scripts.
"""
# Determine platform specifics
have_fork = hasattr(os, 'fork')
have_popen2 = hasattr(os, 'popen2')
have_popen3 = hasattr(os, 'popen3')
# Make rfile unbuffered -- we need to read one line and then pass
# the rest to a subprocess, so we can't use buffered input.
rbufsize = 0
def do_POST(self):
"""Serve a POST request.
This is only implemented for CGI scripts.
"""
if self.is_cgi():
self.run_cgi()
else:
self.send_error(501, "Can only POST to CGI scripts")
def send_head(self):
"""Version of send_head that support CGI scripts"""
if self.is_cgi():
return self.run_cgi()
else:
return SimpleHTTPServer.SimpleHTTPRequestHandler.send_head(self)
def is_cgi(self):
"""Test whether self.path corresponds to a CGI script.
Returns True and updates the cgi_info attribute to the tuple
(dir, rest) if self.path requires running a CGI script.
Returns False otherwise.
If any exception is raised, the caller should assume that
self.path was rejected as invalid and act accordingly.
The default implementation tests whether the normalized url
path begins with one of the strings in self.cgi_directories
(and the next character is a '/' or the end of the string).
"""
collapsed_path = _url_collapse_path(self.path)
dir_sep = collapsed_path.find('/', 1)
head, tail = collapsed_path[:dir_sep], collapsed_path[dir_sep+1:]
if head in self.cgi_directories:
self.cgi_info = head, tail
return True
return False
cgi_directories = ['/cgi-bin', '/htbin']
def is_executable(self, path):
"""Test whether argument path is an executable file."""
return executable(path)
def is_python(self, path):
"""Test whether argument path is a Python script."""
head, tail = os.path.splitext(path)
return tail.lower() in (".py", ".pyw")
def run_cgi(self):
"""Execute a CGI script."""
dir, rest = self.cgi_info
path = dir + '/' + rest
i = path.find('/', len(dir)+1)
while i >= 0:
nextdir = path[:i]
nextrest = path[i+1:]
scriptdir = self.translate_path(nextdir)
if os.path.isdir(scriptdir):
dir, rest = nextdir, nextrest
i = path.find('/', len(dir)+1)
else:
break
# find an explicit query string, if present.
rest, _, query = rest.partition('?')
# dissect the part after the directory name into a script name &
# a possible additional path, to be stored in PATH_INFO.
i = rest.find('/')
if i >= 0:
script, rest = rest[:i], rest[i:]
else:
script, rest = rest, ''
scriptname = dir + '/' + script
scriptfile = self.translate_path(scriptname)
if not os.path.exists(scriptfile):
self.send_error(404, "No such CGI script (%r)" % scriptname)
return
if not os.path.isfile(scriptfile):
self.send_error(403, "CGI script is not a plain file (%r)" %
scriptname)
return
ispy = self.is_python(scriptname)
if not ispy:
if not (self.have_fork or self.have_popen2 or self.have_popen3):
self.send_error(403, "CGI script is not a Python script (%r)" %
scriptname)
return
if not self.is_executable(scriptfile):
self.send_error(403, "CGI script is not executable (%r)" %
scriptname)
return
# Reference: http://hoohoo.ncsa.uiuc.edu/cgi/env.html
# XXX Much of the following could be prepared ahead of time!
env = copy.deepcopy(os.environ)
env['SERVER_SOFTWARE'] = self.version_string()
env['SERVER_NAME'] = self.server.server_name
env['GATEWAY_INTERFACE'] = 'CGI/1.1'
env['SERVER_PROTOCOL'] = self.protocol_version
env['SERVER_PORT'] = str(self.server.server_port)
env['REQUEST_METHOD'] = self.command
uqrest = urllib.unquote(rest)
env['PATH_INFO'] = uqrest
env['PATH_TRANSLATED'] = self.translate_path(uqrest)
env['SCRIPT_NAME'] = scriptname
if query:
env['QUERY_STRING'] = query
host = self.address_string()
if host != self.client_address[0]:
env['REMOTE_HOST'] = host
env['REMOTE_ADDR'] = self.client_address[0]
authorization = self.headers.getheader("authorization")
if authorization:
authorization = authorization.split()
if len(authorization) == 2:
import base64, binascii
env['AUTH_TYPE'] = authorization[0]
if authorization[0].lower() == "basic":
try:
authorization = base64.decodestring(authorization[1])
except binascii.Error:
pass
else:
authorization = authorization.split(':')
if len(authorization) == 2:
env['REMOTE_USER'] = authorization[0]
# XXX REMOTE_IDENT
if self.headers.typeheader is None:
env['CONTENT_TYPE'] = self.headers.type
else:
env['CONTENT_TYPE'] = self.headers.typeheader
length = self.headers.getheader('content-length')
if length:
env['CONTENT_LENGTH'] = length
referer = self.headers.getheader('referer')
if referer:
env['HTTP_REFERER'] = referer
accept = []
for line in self.headers.getallmatchingheaders('accept'):
if line[:1] in "\t\n\r ":
accept.append(line.strip())
else:
accept = accept + line[7:].split(',')
env['HTTP_ACCEPT'] = ','.join(accept)
ua = self.headers.getheader('user-agent')
if ua:
env['HTTP_USER_AGENT'] = ua
co = filter(None, self.headers.getheaders('cookie'))
if co:
env['HTTP_COOKIE'] = ', '.join(co)
# XXX Other HTTP_* headers
# Since we're setting the env in the parent, provide empty
# values to override previously set values
for k in ('QUERY_STRING', 'REMOTE_HOST', 'CONTENT_LENGTH',
'HTTP_USER_AGENT', 'HTTP_COOKIE', 'HTTP_REFERER'):
env.setdefault(k, "")
self.send_response(200, "Script output follows")
decoded_query = query.replace('+', ' ')
if self.have_fork:
# Unix -- fork as we should
args = [script]
if '=' not in decoded_query:
args.append(decoded_query)
nobody = nobody_uid()
self.wfile.flush() # Always flush before forking
pid = os.fork()
if pid != 0:
# Parent
pid, sts = os.waitpid(pid, 0)
# throw away additional data [see bug #427345]
while select.select([self.rfile], [], [], 0)[0]:
if not self.rfile.read(1):
break
if sts:
self.log_error("CGI script exit status %#x", sts)
return
# Child
try:
try:
os.setuid(nobody)
except os.error:
pass
os.dup2(self.rfile.fileno(), 0)
os.dup2(self.wfile.fileno(), 1)
os.execve(scriptfile, args, env)
except:
self.server.handle_error(self.request, self.client_address)
os._exit(127)
else:
# Non Unix - use subprocess
import subprocess
cmdline = [scriptfile]
if self.is_python(scriptfile):
interp = sys.executable
if interp.lower().endswith("w.exe"):
# On Windows, use python.exe, not pythonw.exe
interp = interp[:-5] + interp[-4:]
cmdline = [interp, '-u'] + cmdline
if '=' not in query:
cmdline.append(query)
self.log_message("command: %s", subprocess.list2cmdline(cmdline))
try:
nbytes = int(length)
except (TypeError, ValueError):
nbytes = 0
p = subprocess.Popen(cmdline,
stdin = subprocess.PIPE,
stdout = subprocess.PIPE,
stderr = subprocess.PIPE,
env = env
)
if self.command.lower() == "post" and nbytes > 0:
data = self.rfile.read(nbytes)
else:
data = None
# throw away additional data [see bug #427345]
while select.select([self.rfile._sock], [], [], 0)[0]:
if not self.rfile._sock.recv(1):
break
stdout, stderr = p.communicate(data)
self.wfile.write(stdout)
if stderr:
self.log_error('%s', stderr)
p.stderr.close()
p.stdout.close()
status = p.returncode
if status:
self.log_error("CGI script exit status %#x", status)
else:
self.log_message("CGI script exited OK")
def _url_collapse_path(path):
"""
Given a URL path, remove extra '/'s and '.' path elements and collapse
any '..' references and returns a colllapsed path.
Implements something akin to RFC-2396 5.2 step 6 to parse relative paths.
The utility of this function is limited to is_cgi method and helps
preventing some security attacks.
Returns: The reconstituted URL, which will always start with a '/'.
Raises: IndexError if too many '..' occur within the path.
"""
# Query component should not be involved.
path, _, query = path.partition('?')
path = urllib.unquote(path)
# Similar to os.path.split(os.path.normpath(path)) but specific to URL
# path semantics rather than local operating system semantics.
path_parts = path.split('/')
head_parts = []
for part in path_parts[:-1]:
if part == '..':
head_parts.pop() # IndexError if more '..' than prior parts
elif part and part != '.':
head_parts.append( part )
if path_parts:
tail_part = path_parts.pop()
if tail_part:
if tail_part == '..':
head_parts.pop()
tail_part = ''
elif tail_part == '.':
tail_part = ''
else:
tail_part = ''
if query:
tail_part = '?'.join((tail_part, query))
splitpath = ('/' + '/'.join(head_parts), tail_part)
collapsed_path = "/".join(splitpath)
return collapsed_path
nobody = None
def nobody_uid():
"""Internal routine to get nobody's uid"""
global nobody
if nobody:
return nobody
try:
import pwd
except ImportError:
return -1
try:
nobody = pwd.getpwnam('nobody')[2]
except KeyError:
nobody = 1 + max(map(lambda x: x[2], pwd.getpwall()))
return nobody
def executable(path):
"""Test for executable file."""
try:
st = os.stat(path)
except os.error:
return False
return st.st_mode & 0111 != 0
def test(HandlerClass = CGIHTTPRequestHandler,
ServerClass = BaseHTTPServer.HTTPServer):
SimpleHTTPServer.test(HandlerClass, ServerClass)
if __name__ == '__main__':
test()
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