Added a SCGI-WSGI gateway for Python.

[ashd.git] / python / ashd / scgi.py

diff --git a/python/ashd/scgi.py b/python/ashd/scgi.py
new file mode 100644 (file)
index 0000000..9357e9d
--- /dev/null
+++ b/python/ashd/scgi.py
@@ -0,0 +1,113 @@
+import sys
+import threading
+
+class protoerr(Exception):
+    pass
+
+def readns(sk):
+    hln = 0
+    while True:
+        c = sk.read(1)
+        if c == ':':
+            break
+        elif c >= '0' or c <= '9':
+            hln = (hln * 10) + (ord(c) - ord('0'))
+        else:
+            raise protoerr, "Invalid netstring length byte: " + c
+    ret = sk.read(hln)
+    if sk.read(1) != ',':
+        raise protoerr, "Non-terminated netstring"
+    return ret
+
+def readhead(sk):
+    parts = readns(sk).split('\0')[:-1]
+    if len(parts) % 2 != 0:
+        raise protoerr, "Malformed headers"
+    ret = {}
+    i = 0
+    while i < len(parts):
+        ret[parts[i]] = parts[i + 1]
+        i += 2
+    return ret
+
+class reqthread(threading.Thread):
+    def __init__(self, sk, handler):
+        super(reqthread, self).__init__(name = "SCGI request handler")
+        self.sk = sk.dup().makefile("r+")
+        self.handler = handler
+
+    def run(self):
+        try:
+            head = readhead(self.sk)
+            self.handler(head, self.sk)
+        finally:
+            self.sk.close()
+
+def handlescgi(sk, handler):
+    t = reqthread(sk, handler)
+    t.start()
+
+def servescgi(socket, handler):
+    while True:
+        nsk, addr = socket.accept()
+        try:
+            handlescgi(nsk, handler)
+        finally:
+            nsk.close()
+
+def wrapwsgi(handler):
+    def handle(head, sk):
+        env = dict(head)
+        env["wsgi.version"] = 1, 0
+        if "HTTP_X_ASH_PROTOCOL" in env:
+            env["wsgi.url_scheme"] = env["HTTP_X_ASH_PROTOCOL"]
+        elif "HTTPS" in env:
+            env["wsgi.url_scheme"] = "https"
+        else:
+            env["wsgi.url_scheme"] = "http"
+        env["wsgi.input"] = sk
+        env["wsgi.errors"] = sys.stderr
+        env["wsgi.multithread"] = True
+        env["wsgi.multiprocess"] = False
+        env["wsgi.run_once"] = False
+
+        resp = []
+        respsent = []
+
+        def write(data):
+            if not data:
+                return
+            if not respsent:
+                if not resp:
+                    raise Exception, "Trying to write data before starting response."
+                status, headers = resp
+                respsent[:] = [True]
+                sk.write("Status: %s\n" % status)
+                for nm, val in headers:
+                    sk.write("%s: %s\n" % (nm, val))
+                sk.write("\n")
+            sk.write(data)
+            sk.flush()
+
+        def startreq(status, headers, exc_info = None):
+            if resp:
+                if exc_info:                # Interesting, this...
+                    try:
+                        if respsent:
+                            raise exc_info[0], exc_info[1], exc_info[2]
+                    finally:
+                        exc_info = None     # CPython GC bug?
+                else:
+                    raise Exception, "Can only start responding once."
+            resp[:] = status, headers
+            return write
+
+        respiter = handler(env, startreq)
+        try:
+            for data in respiter:
+                write(data)
+            write("")
+        finally:
+            if hasattr(respiter, "close"):
+                respiter.close()
+    return handle