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.sk = sk.dup().makefile("rwb")
  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 decodehead(head, coding):
  63     return {k.decode(coding): v.decode(coding) for k, v in head.items()}
  64
  65 def wrapwsgi(handler):
  66     def handle(head, sk):
  67         try:
  68             env = decodehead(head, "utf-8")
  69             env["wsgi.uri_encoding"] = "utf-8"
  70         except UnicodeError:
  71             env = decodehead(head, "latin-1")
  72             env["wsgi.uri_encoding"] = "latin-1"
  73         env["wsgi.version"] = 1, 0
  74         if "HTTP_X_ASH_PROTOCOL" in env:
  75             env["wsgi.url_scheme"] = env["HTTP_X_ASH_PROTOCOL"]
  76         elif "HTTPS" in env:
  77             env["wsgi.url_scheme"] = "https"
  78         else:
  79             env["wsgi.url_scheme"] = "http"
  80         env["wsgi.input"] = sk
  81         env["wsgi.errors"] = sys.stderr
  82         env["wsgi.multithread"] = True
  83         env["wsgi.multiprocess"] = False
  84         env["wsgi.run_once"] = False
  85
  86         resp = []
  87         respsent = []
  88
  89         def recode(thing):
  90             if isinstance(thing, collections.ByteString):
  91                 return thing
  92             else:
  93                 return str(thing).encode("latin-1")
  94
  95         def flushreq():
  96             if not respsent:
  97                 if not resp:
  98                     raise Exception("Trying to write data before starting response.")
  99                 status, headers = resp
 100                 respsent[:] = [True]
 101                 buf = bytearray()
 102                 buf += b"Status: " + recode(status) + b"\n"
 103                 for nm, val in headers:
 104                     buf += recode(nm) + b": " + recode(val) + b"\n"
 105                 buf += b"\n"
 106                 try:
 107                     sk.write(buf)
 108                 except IOError:
 109                     raise closed()
 110
 111         def write(data):
 112             if not data:
 113                 return
 114             flushreq()
 115             try:
 116                 sk.write(data)
 117                 sk.flush()
 118             except IOError:
 119                 raise closed()
 120
 121         def startreq(status, headers, exc_info = None):
 122             if resp:
 123                 if exc_info:                # Interesting, this...
 124                     try:
 125                         if respsent:
 126                             raise exc_info[1]
 127                     finally:
 128                         exc_info = None     # CPython GC bug?
 129                 else:
 130                     raise Exception("Can only start responding once.")
 131             resp[:] = status, headers
 132             return write
 133
 134         respiter = handler(env, startreq)
 135         try:
 136             try:
 137                 for data in respiter:
 138                     write(data)
 139                 if resp:
 140                     flushreq()
 141             except closed:
 142                 pass
 143         finally:
 144             if hasattr(respiter, "close"):
 145                 respiter.close()
 146     return handle