python3/ashd/scgi.py

   1 import sys, collections
   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 == b':':
  16             break
  17         elif c >= b'0' or c <= b'9':
  18             hln = (hln * 10) + (ord(c) - ord(b'0'))
  19         else:
  20             raise protoerr("Invalid netstring length byte: " + c)
  21     ret = sk.read(hln)
  22     if sk.read(1) != b',':
  23         raise protoerr("Non-terminated netstring")
  24     return ret
  25
  26 def readhead(sk):
  27     parts = readns(sk).split(b'\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.bsk = sk.dup()
  41         self.sk = self.bsk.makefile("rwb")
  42         self.handler = handler
  43
  44     def run(self):
  45         try:
  46             head = readhead(self.sk)
  47             self.handler(head, self.sk)
  48         finally:
  49             self.sk.close()
  50             self.bsk.close()
  51
  52 def handlescgi(sk, handler):
  53     t = reqthread(sk, handler)
  54     t.start()
  55
  56 def servescgi(socket, handler):
  57     while True:
  58         nsk, addr = socket.accept()
  59         try:
  60             handlescgi(nsk, handler)
  61         finally:
  62             nsk.close()
  63
  64 def decodehead(head, coding):
  65     return {k.decode(coding): v.decode(coding) for k, v in head.items()}
  66
  67 def wrapwsgi(handler):
  68     def handle(head, sk):
  69         try:
  70             env = decodehead(head, "utf-8")
  71             env["wsgi.uri_encoding"] = "utf-8"
  72         except UnicodeError:
  73             env = decodehead(head, "latin-1")
  74             env["wsgi.uri_encoding"] = "latin-1"
  75         env["wsgi.version"] = 1, 0
  76         if "HTTP_X_ASH_PROTOCOL" in env:
  77             env["wsgi.url_scheme"] = env["HTTP_X_ASH_PROTOCOL"]
  78         elif "HTTPS" in env:
  79             env["wsgi.url_scheme"] = "https"
  80         else:
  81             env["wsgi.url_scheme"] = "http"
  82         env["wsgi.input"] = sk
  83         env["wsgi.errors"] = sys.stderr
  84         env["wsgi.multithread"] = True
  85         env["wsgi.multiprocess"] = False
  86         env["wsgi.run_once"] = False
  87
  88         resp = []
  89         respsent = []
  90
  91         def recode(thing):
  92             if isinstance(thing, collections.ByteString):
  93                 return thing
  94             else:
  95                 return str(thing).encode("latin-1")
  96
  97         def flushreq():
  98             if not respsent:
  99                 if not resp:
 100                     raise Exception("Trying to write data before starting response.")
 101                 status, headers = resp
 102                 respsent[:] = [True]
 103                 buf = bytearray()
 104                 buf += b"Status: " + recode(status) + b"\n"
 105                 for nm, val in headers:
 106                     buf += recode(nm) + b": " + recode(val) + b"\n"
 107                 buf += b"\n"
 108                 try:
 109                     sk.write(buf)
 110                 except IOError:
 111                     raise closed()
 112
 113         def write(data):
 114             if not data:
 115                 return
 116             flushreq()
 117             try:
 118                 sk.write(data)
 119                 sk.flush()
 120             except IOError:
 121                 raise closed()
 122
 123         def startreq(status, headers, exc_info = None):
 124             if resp:
 125                 if exc_info:                # Interesting, this...
 126                     try:
 127                         if respsent:
 128                             raise exc_info[1]
 129                     finally:
 130                         exc_info = None     # CPython GC bug?
 131                 else:
 132                     raise Exception("Can only start responding once.")
 133             resp[:] = status, headers
 134             return write
 135
 136         respiter = handler(env, startreq)
 137         try:
 138             try:
 139                 for data in respiter:
 140                     write(data)
 141                 if resp:
 142                     flushreq()
 143             except closed:
 144                 pass
 145         finally:
 146             if hasattr(respiter, "close"):
 147                 respiter.close()
 148     return handle