python/ashd/scgi.py

   1 import sys
   2 import threading
   3
   4 class protoerr(Exception):
   5     pass
   6
   7 def readns(sk):
   8     hln = 0
   9     while True:
  10         c = sk.read(1)
  11         if c == ':':
  12             break
  13         elif c >= '0' or c <= '9':
  14             hln = (hln * 10) + (ord(c) - ord('0'))
  15         else:
  16             raise protoerr, "Invalid netstring length byte: " + c
  17     ret = sk.read(hln)
  18     if sk.read(1) != ',':
  19         raise protoerr, "Non-terminated netstring"
  20     return ret
  21
  22 def readhead(sk):
  23     parts = readns(sk).split('\0')[:-1]
  24     if len(parts) % 2 != 0:
  25         raise protoerr, "Malformed headers"
  26     ret = {}
  27     i = 0
  28     while i < len(parts):
  29         ret[parts[i]] = parts[i + 1]
  30         i += 2
  31     return ret
  32
  33 class reqthread(threading.Thread):
  34     def __init__(self, sk, handler):
  35         super(reqthread, self).__init__(name = "SCGI request handler")
  36         self.sk = sk.dup().makefile("r+")
  37         self.handler = handler
  38
  39     def run(self):
  40         try:
  41             head = readhead(self.sk)
  42             self.handler(head, self.sk)
  43         finally:
  44             self.sk.close()
  45
  46 def handlescgi(sk, handler):
  47     t = reqthread(sk, handler)
  48     t.start()
  49
  50 def servescgi(socket, handler):
  51     while True:
  52         nsk, addr = socket.accept()
  53         try:
  54             handlescgi(nsk, handler)
  55         finally:
  56             nsk.close()
  57
  58 def wrapwsgi(handler):
  59     def handle(head, sk):
  60         env = dict(head)
  61         env["wsgi.version"] = 1, 0
  62         if "HTTP_X_ASH_PROTOCOL" in env:
  63             env["wsgi.url_scheme"] = env["HTTP_X_ASH_PROTOCOL"]
  64         elif "HTTPS" in env:
  65             env["wsgi.url_scheme"] = "https"
  66         else:
  67             env["wsgi.url_scheme"] = "http"
  68         env["wsgi.input"] = sk
  69         env["wsgi.errors"] = sys.stderr
  70         env["wsgi.multithread"] = True
  71         env["wsgi.multiprocess"] = False
  72         env["wsgi.run_once"] = False
  73
  74         resp = []
  75         respsent = []
  76
  77         def write(data):
  78             if not data:
  79                 return
  80             if not respsent:
  81                 if not resp:
  82                     raise Exception, "Trying to write data before starting response."
  83                 status, headers = resp
  84                 respsent[:] = [True]
  85                 sk.write("Status: %s\n" % status)
  86                 for nm, val in headers:
  87                     sk.write("%s: %s\n" % (nm, val))
  88                 sk.write("\n")
  89             sk.write(data)
  90             sk.flush()
  91
  92         def startreq(status, headers, exc_info = None):
  93             if resp:
  94                 if exc_info:                # Interesting, this...
  95                     try:
  96                         if respsent:
  97                             raise exc_info[0], exc_info[1], exc_info[2]
  98                     finally:
  99                         exc_info = None     # CPython GC bug?
 100                 else:
 101                     raise Exception, "Can only start responding once."
 102             resp[:] = status, headers
 103             return write
 104
 105         respiter = handler(env, startreq)
 106         try:
 107             for data in respiter:
 108                 write(data)
 109             write("")
 110         finally:
 111             if hasattr(respiter, "close"):
 112                 respiter.close()
 113     return handle