python/ashd/scgi.py

   1 import sys
   2 import threading
   3
   4 class protoerr(Exception):
   5     pass
   6
   7 class closed(IOError):
   8     def __init__(self):
   9         super(closed, self).__init__("The client has closed the connection.")
  10
  11 def readns(sk):
  12     hln = 0
  13     while True:
  14         c = sk.read(1)
  15         if c == ':':
  16             break
  17         elif c >= '0' or c <= '9':
  18             hln = (hln * 10) + (ord(c) - ord('0'))
  19         else:
  20             raise protoerr, "Invalid netstring length byte: " + c
  21     ret = sk.read(hln)
  22     if sk.read(1) != ',':
  23         raise protoerr, "Non-terminated netstring"
  24     return ret
  25
  26 def readhead(sk):
  27     parts = readns(sk).split('\0')[:-1]
  28     if len(parts) % 2 != 0:
  29         raise protoerr, "Malformed headers"
  30     ret = {}
  31     i = 0
  32     while i < len(parts):
  33         ret[parts[i]] = parts[i + 1]
  34         i += 2
  35     return ret
  36
  37 class reqthread(threading.Thread):
  38     def __init__(self, sk, handler):
  39         super(reqthread, self).__init__(name = "SCGI request handler")
  40         self.sk = sk.dup().makefile("r+")
  41         self.handler = handler
  42
  43     def run(self):
  44         try:
  45             head = readhead(self.sk)
  46             self.handler(head, self.sk)
  47         finally:
  48             self.sk.close()
  49
  50 def handlescgi(sk, handler):
  51     t = reqthread(sk, handler)
  52     t.start()
  53
  54 def servescgi(socket, handler):
  55     while True:
  56         nsk, addr = socket.accept()
  57         try:
  58             handlescgi(nsk, handler)
  59         finally:
  60             nsk.close()
  61
  62 def wrapwsgi(handler):
  63     def handle(head, sk):
  64         env = dict(head)
  65         env["wsgi.version"] = 1, 0
  66         if "HTTP_X_ASH_PROTOCOL" in env:
  67             env["wsgi.url_scheme"] = env["HTTP_X_ASH_PROTOCOL"]
  68         elif "HTTPS" in env:
  69             env["wsgi.url_scheme"] = "https"
  70         else:
  71             env["wsgi.url_scheme"] = "http"
  72         env["wsgi.input"] = sk
  73         env["wsgi.errors"] = sys.stderr
  74         env["wsgi.multithread"] = True
  75         env["wsgi.multiprocess"] = False
  76         env["wsgi.run_once"] = False
  77
  78         resp = []
  79         respsent = []
  80
  81         def flushreq():
  82             if not respsent:
  83                 if not resp:
  84                     raise Exception, "Trying to write data before starting response."
  85                 status, headers = resp
  86                 respsent[:] = [True]
  87                 try:
  88                     sk.write("Status: %s\n" % status)
  89                     for nm, val in headers:
  90                         sk.write("%s: %s\n" % (nm, val))
  91                     sk.write("\n")
  92                 except IOError:
  93                     raise closed()
  94
  95         def write(data):
  96             if not data:
  97                 return
  98             flushreq()
  99             try:
 100                 sk.write(data)
 101                 sk.flush()
 102             except IOError:
 103                 raise closed()
 104
 105         def startreq(status, headers, exc_info = None):
 106             if resp:
 107                 if exc_info:                # Interesting, this...
 108                     try:
 109                         if respsent:
 110                             raise exc_info[0], exc_info[1], exc_info[2]
 111                     finally:
 112                         exc_info = None     # CPython GC bug?
 113                 else:
 114                     raise Exception, "Can only start responding once."
 115             resp[:] = status, headers
 116             return write
 117
 118         respiter = handler(env, startreq)
 119         try:
 120             try:
 121                 for data in respiter:
 122                     write(data)
 123                 if resp:
 124                     flushreq()
 125             except closed:
 126                 pass
 127         finally:
 128             if hasattr(respiter, "close"):
 129                 respiter.close()
 130     return handle