Lib/CGIHTTPServer.py

   1 """CGI-savvy HTTP Server.
   2
   3 This module builds on SimpleHTTPServer by implementing GET and POST
   4 requests to cgi-bin scripts.
   5
   6 If the os.fork() function is not present (e.g. on Windows),
   7 os.popen2() is used as a fallback, with slightly altered semantics; if
   8 that function is not present either (e.g. on Macintosh), only Python
   9 scripts are supported, and they are executed by the current process.
  10
  11 In all cases, the implementation is intentionally naive -- all
  12 requests are executed sychronously.
  13
  14 SECURITY WARNING: DON'T USE THIS CODE UNLESS YOU ARE INSIDE A FIREWALL
  15 -- it may execute arbitrary Python code or external programs.
  16
  17 Note that status code 200 is sent prior to execution of a CGI script, so
  18 scripts cannot send other status codes such as 302 (redirect).
  19 """
  20
  21
  22 __version__ = "0.4"
  23
  24 __all__ = ["CGIHTTPRequestHandler"]
  25
  26 import os
  27 import sys
  28 import urllib
  29 import BaseHTTPServer
  30 import SimpleHTTPServer
  31 import select
  32
  33
  34 class CGIHTTPRequestHandler(SimpleHTTPServer.SimpleHTTPRequestHandler):
  35
  36     """Complete HTTP server with GET, HEAD and POST commands.
  37
  38     GET and HEAD also support running CGI scripts.
  39
  40     The POST command is *only* implemented for CGI scripts.
  41
  42     """
  43
  44     # Determine platform specifics
  45     have_fork = hasattr(os, 'fork')
  46     have_popen2 = hasattr(os, 'popen2')
  47     have_popen3 = hasattr(os, 'popen3')
  48
  49     # Make rfile unbuffered -- we need to read one line and then pass
  50     # the rest to a subprocess, so we can't use buffered input.
  51     rbufsize = 0
  52
  53     def do_POST(self):
  54         """Serve a POST request.
  55
  56         This is only implemented for CGI scripts.
  57
  58         """
  59
  60         if self.is_cgi():
  61             self.run_cgi()
  62         else:
  63             self.send_error(501, "Can only POST to CGI scripts")
  64
  65     def send_head(self):
  66         """Version of send_head that support CGI scripts"""
  67         if self.is_cgi():
  68             return self.run_cgi()
  69         else:
  70             return SimpleHTTPServer.SimpleHTTPRequestHandler.send_head(self)
  71
  72     def is_cgi(self):
  73         """Test whether self.path corresponds to a CGI script.
  74
  75         Return a tuple (dir, rest) if self.path requires running a
  76         CGI script, None if not.  Note that rest begins with a
  77         slash if it is not empty.
  78
  79         The default implementation tests whether the path
  80         begins with one of the strings in the list
  81         self.cgi_directories (and the next character is a '/'
  82         or the end of the string).
  83
  84         """
  85
  86         path = self.path
  87
  88         for x in self.cgi_directories:
  89             i = len(x)
  90             if path[:i] == x and (not path[i:] or path[i] == '/'):
  91                 self.cgi_info = path[:i], path[i+1:]
  92                 return True
  93         return False
  94
  95     cgi_directories = ['/cgi-bin', '/htbin']
  96
  97     def is_executable(self, path):
  98         """Test whether argument path is an executable file."""
  99         return executable(path)
 100
 101     def is_python(self, path):
 102         """Test whether argument path is a Python script."""
 103         head, tail = os.path.splitext(path)
 104         return tail.lower() in (".py", ".pyw")
 105
 106     def run_cgi(self):
 107         """Execute a CGI script."""
 108         path = self.path
 109         dir, rest = self.cgi_info
 110
 111         i = path.find('/', len(dir) + 1)
 112         while i >= 0:
 113             nextdir = path[:i]
 114             nextrest = path[i+1:]
 115
 116             scriptdir = self.translate_path(nextdir)
 117             if os.path.isdir(scriptdir):
 118                 dir, rest = nextdir, nextrest
 119                 i = path.find('/', len(dir) + 1)
 120             else:
 121                 break
 122
 123         # find an explicit query string, if present.
 124         i = rest.rfind('?')
 125         if i >= 0:
 126             rest, query = rest[:i], rest[i+1:]
 127         else:
 128             query = ''
 129
 130         # dissect the part after the directory name into a script name &
 131         # a possible additional path, to be stored in PATH_INFO.
 132         i = rest.find('/')
 133         if i >= 0:
 134             script, rest = rest[:i], rest[i:]
 135         else:
 136             script, rest = rest, ''
 137
 138         scriptname = dir + '/' + script
 139         scriptfile = self.translate_path(scriptname)
 140         if not os.path.exists(scriptfile):
 141             self.send_error(404, "No such CGI script (%r)" % scriptname)
 142             return
 143         if not os.path.isfile(scriptfile):
 144             self.send_error(403, "CGI script is not a plain file (%r)" %
 145                             scriptname)
 146             return
 147         ispy = self.is_python(scriptname)
 148         if not ispy:
 149             if not (self.have_fork or self.have_popen2 or self.have_popen3):
 150                 self.send_error(403, "CGI script is not a Python script (%r)" %
 151                                 scriptname)
 152                 return
 153             if not self.is_executable(scriptfile):
 154                 self.send_error(403, "CGI script is not executable (%r)" %
 155                                 scriptname)
 156                 return
 157
 158         # Reference: http://hoohoo.ncsa.uiuc.edu/cgi/env.html
 159         # XXX Much of the following could be prepared ahead of time!
 160         env = {}
 161         env['SERVER_SOFTWARE'] = self.version_string()
 162         env['SERVER_NAME'] = self.server.server_name
 163         env['GATEWAY_INTERFACE'] = 'CGI/1.1'
 164         env['SERVER_PROTOCOL'] = self.protocol_version
 165         env['SERVER_PORT'] = str(self.server.server_port)
 166         env['REQUEST_METHOD'] = self.command
 167         uqrest = urllib.unquote(rest)
 168         env['PATH_INFO'] = uqrest
 169         env['PATH_TRANSLATED'] = self.translate_path(uqrest)
 170         env['SCRIPT_NAME'] = scriptname
 171         if query:
 172             env['QUERY_STRING'] = query
 173         host = self.address_string()
 174         if host != self.client_address[0]:
 175             env['REMOTE_HOST'] = host
 176         env['REMOTE_ADDR'] = self.client_address[0]
 177         authorization = self.headers.getheader("authorization")
 178         if authorization:
 179             authorization = authorization.split()
 180             if len(authorization) == 2:
 181                 import base64, binascii
 182                 env['AUTH_TYPE'] = authorization[0]
 183                 if authorization[0].lower() == "basic":
 184                     try:
 185                         authorization = base64.decodestring(authorization[1])
 186                     except binascii.Error:
 187                         pass
 188                     else:
 189                         authorization = authorization.split(':')
 190                         if len(authorization) == 2:
 191                             env['REMOTE_USER'] = authorization[0]
 192         # XXX REMOTE_IDENT
 193         if self.headers.typeheader is None:
 194             env['CONTENT_TYPE'] = self.headers.type
 195         else:
 196             env['CONTENT_TYPE'] = self.headers.typeheader
 197         length = self.headers.getheader('content-length')
 198         if length:
 199             env['CONTENT_LENGTH'] = length
 200         accept = []
 201         for line in self.headers.getallmatchingheaders('accept'):
 202             if line[:1] in "\t\n\r ":
 203                 accept.append(line.strip())
 204             else:
 205                 accept = accept + line[7:].split(',')
 206         env['HTTP_ACCEPT'] = ','.join(accept)
 207         ua = self.headers.getheader('user-agent')
 208         if ua:
 209             env['HTTP_USER_AGENT'] = ua
 210         co = filter(None, self.headers.getheaders('cookie'))
 211         if co:
 212             env['HTTP_COOKIE'] = ', '.join(co)
 213         # XXX Other HTTP_* headers
 214         # Since we're setting the env in the parent, provide empty
 215         # values to override previously set values
 216         for k in ('QUERY_STRING', 'REMOTE_HOST', 'CONTENT_LENGTH',
 217                   'HTTP_USER_AGENT', 'HTTP_COOKIE'):
 218             env.setdefault(k, "")
 219         os.environ.update(env)
 220
 221         self.send_response(200, "Script output follows")
 222
 223         decoded_query = query.replace('+', ' ')
 224
 225         if self.have_fork:
 226             # Unix -- fork as we should
 227             args = [script]
 228             if '=' not in decoded_query:
 229                 args.append(decoded_query)
 230             nobody = nobody_uid()
 231             self.wfile.flush() # Always flush before forking
 232             pid = os.fork()
 233             if pid != 0:
 234                 # Parent
 235                 pid, sts = os.waitpid(pid, 0)
 236                 # throw away additional data [see bug #427345]
 237                 while select.select([self.rfile], [], [], 0)[0]:
 238                     if not self.rfile.read(1):
 239                         break
 240                 if sts:
 241                     self.log_error("CGI script exit status %#x", sts)
 242                 return
 243             # Child
 244             try:
 245                 try:
 246                     os.setuid(nobody)
 247                 except os.error:
 248                     pass
 249                 os.dup2(self.rfile.fileno(), 0)
 250                 os.dup2(self.wfile.fileno(), 1)
 251                 os.execve(scriptfile, args, os.environ)
 252             except:
 253                 self.server.handle_error(self.request, self.client_address)
 254                 os._exit(127)
 255
 256         elif self.have_popen2 or self.have_popen3:
 257             # Windows -- use popen2 or popen3 to create a subprocess
 258             import shutil
 259             if self.have_popen3:
 260                 popenx = os.popen3
 261             else:
 262                 popenx = os.popen2
 263             cmdline = scriptfile
 264             if self.is_python(scriptfile):
 265                 interp = sys.executable
 266                 if interp.lower().endswith("w.exe"):
 267                     # On Windows, use python.exe, not pythonw.exe
 268                     interp = interp[:-5] + interp[-4:]
 269                 cmdline = "%s -u %s" % (interp, cmdline)
 270             if '=' not in query and '"' not in query:
 271                 cmdline = '%s "%s"' % (cmdline, query)
 272             self.log_message("command: %s", cmdline)
 273             try:
 274                 nbytes = int(length)
 275             except (TypeError, ValueError):
 276                 nbytes = 0
 277             files = popenx(cmdline, 'b')
 278             fi = files[0]
 279             fo = files[1]
 280             if self.have_popen3:
 281                 fe = files[2]
 282             if self.command.lower() == "post" and nbytes > 0:
 283                 data = self.rfile.read(nbytes)
 284                 fi.write(data)
 285             # throw away additional data [see bug #427345]
 286             while select.select([self.rfile._sock], [], [], 0)[0]:
 287                 if not self.rfile._sock.recv(1):
 288                     break
 289             fi.close()
 290             shutil.copyfileobj(fo, self.wfile)
 291             if self.have_popen3:
 292                 errors = fe.read()
 293                 fe.close()
 294                 if errors:
 295                     self.log_error('%s', errors)
 296             sts = fo.close()
 297             if sts:
 298                 self.log_error("CGI script exit status %#x", sts)
 299             else:
 300                 self.log_message("CGI script exited OK")
 301
 302         else:
 303             # Other O.S. -- execute script in this process
 304             save_argv = sys.argv
 305             save_stdin = sys.stdin
 306             save_stdout = sys.stdout
 307             save_stderr = sys.stderr
 308             try:
 309                 save_cwd = os.getcwd()
 310                 try:
 311                     sys.argv = [scriptfile]
 312                     if '=' not in decoded_query:
 313                         sys.argv.append(decoded_query)
 314                     sys.stdout = self.wfile
 315                     sys.stdin = self.rfile
 316                     execfile(scriptfile, {"__name__": "__main__"})
 317                 finally:
 318                     sys.argv = save_argv
 319                     sys.stdin = save_stdin
 320                     sys.stdout = save_stdout
 321                     sys.stderr = save_stderr
 322                     os.chdir(save_cwd)
 323             except SystemExit, sts:
 324                 self.log_error("CGI script exit status %s", str(sts))
 325             else:
 326                 self.log_message("CGI script exited OK")
 327
 328
 329 nobody = None
 330
 331 def nobody_uid():
 332     """Internal routine to get nobody's uid"""
 333     global nobody
 334     if nobody:
 335         return nobody
 336     try:
 337         import pwd
 338     except ImportError:
 339         return -1
 340     try:
 341         nobody = pwd.getpwnam('nobody')[2]
 342     except KeyError:
 343         nobody = 1 + max(map(lambda x: x[2], pwd.getpwall()))
 344     return nobody
 345
 346
 347 def executable(path):
 348     """Test for executable file."""
 349     try:
 350         st = os.stat(path)
 351     except os.error:
 352         return False
 353     return st.st_mode & 0111 != 0
 354
 355
 356 def test(HandlerClass = CGIHTTPRequestHandler,
 357          ServerClass = BaseHTTPServer.HTTPServer):
 358     SimpleHTTPServer.test(HandlerClass, ServerClass)
 359
 360
 361 if __name__ == '__main__':
 362     test()