"""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

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.

        Return a tuple (dir, rest) if self.path requires running a

        CGI script, None if not.  Note that rest begins with a

        slash if it is not empty.

        The default implementation tests whether the path

        begins with one of the strings in the list

        self.cgi_directories (and the next character is a '/'

        or the end of the string).

        """

        path = self.path

        for x in self.cgi_directories:

            i = len(x)

            if path[:i] == x and (not path[i:] or path[i] == '/'):

                self.cgi_info = path[:i], path[i+1:]

                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."""

        path = self.path

        dir, rest = self.cgi_info

        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.

        i = rest.rfind('?')

        if i >= 0:

            rest, query = rest[:i], rest[i+1:]

        else:

            query = ''

        # 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 = {}

        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

        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'):

            env.setdefault(k, "")

        os.environ.update(env)

        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, os.environ)

            except:

                self.server.handle_error(self.request, self.client_address)

                os._exit(127)

        elif self.have_popen2 or self.have_popen3:

            # Windows -- use popen2 or popen3 to create a subprocess

            import shutil

            if self.have_popen3:

                popenx = os.popen3

            else:

                popenx = os.popen2

            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 = "%s -u %s" % (interp, cmdline)

            if '=' not in query and '"' not in query:

                cmdline = '%s "%s"' % (cmdline, query)

            self.log_message("command: %s", cmdline)

            try:

                nbytes = int(length)

            except (TypeError, ValueError):

                nbytes = 0

            files = popenx(cmdline, 'b')

            fi = files[0]

            fo = files[1]

            if self.have_popen3:

                fe = files[2]

            if self.command.lower() == "post" and nbytes > 0:

                data = self.rfile.read(nbytes)

                fi.write(data)

            # throw away additional data [see bug #427345]

            while select.select([self.rfile._sock], [], [], 0)[0]:

                if not self.rfile._sock.recv(1):

                    break

            fi.close()

            shutil.copyfileobj(fo, self.wfile)

            if self.have_popen3:

                errors = fe.read()

                fe.close()

                if errors:

                    self.log_error('%s', errors)

            sts = fo.close()

            if sts:

                self.log_error("CGI script exit status %#x", sts)

            else:

                self.log_message("CGI script exited OK")

        else:

            # Other O.S. -- execute script in this process

            save_argv = sys.argv

            save_stdin = sys.stdin

            save_stdout = sys.stdout

            save_stderr = sys.stderr

            try:

                save_cwd = os.getcwd()

                try:

                    sys.argv = [scriptfile]

                    if '=' not in decoded_query:

                        sys.argv.append(decoded_query)

                    sys.stdout = self.wfile

                    sys.stdin = self.rfile

                    execfile(scriptfile, {"__name__": "__main__"})

                finally:

                    sys.argv = save_argv

                    sys.stdin = save_stdin

                    sys.stdout = save_stdout

                    sys.stderr = save_stderr

                    os.chdir(save_cwd)

            except SystemExit, sts:

                self.log_error("CGI script exit status %s", str(sts))

            else:

                self.log_message("CGI script exited OK")

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()