1 files changed, 172 insertions, 0 deletions
diff --git a/paste/util/scgiserver.py b/paste/util/scgiserver.py
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+"""
+SCGI-->WSGI application proxy, "SWAP".
+
+(Originally written by Titus Brown.)
+
+This lets an SCGI front-end like mod_scgi be used to execute WSGI
+application objects.  To use it, subclass the SWAP class like so::
+
+   class TestAppHandler(swap.SWAP):
+       def __init__(self, *args, **kwargs):
+           self.prefix = '/canal'
+           self.app_obj = TestAppClass
+           swap.SWAP.__init__(self, *args, **kwargs)
+
+where 'TestAppClass' is the application object from WSGI and '/canal'
+is the prefix for what is served by the SCGI Web-server-side process.
+
+Then execute the SCGI handler "as usual" by doing something like this::
+
+   scgi_server.SCGIServer(TestAppHandler, port=4000).serve()
+
+and point mod_scgi (or whatever your SCGI front end is) at port 4000.
+
+Kudos to the WSGI folk for writing a nice PEP & the Quixote folk for
+writing a nice extensible SCGI server for Python!
+"""
+
+import six
+import sys
+import time
+from scgi import scgi_server
+
+def debug(msg):
+    timestamp = time.strftime("%Y-%m-%d %H:%M:%S",
+                              time.localtime(time.time()))
+    sys.stderr.write("[%s] %s\n" % (timestamp, msg))
+
+class SWAP(scgi_server.SCGIHandler):
+    """
+    SCGI->WSGI application proxy: let an SCGI server execute WSGI
+    application objects.
+    """
+    app_obj = None
+    prefix = None
+
+    def __init__(self, *args, **kwargs):
+        assert self.app_obj, "must set app_obj"
+        assert self.prefix is not None, "must set prefix"
+        args = (self,) + args
+        scgi_server.SCGIHandler.__init__(*args, **kwargs)
+
+    def handle_connection(self, conn):
+        """
+        Handle an individual connection.
+        """
+        input = conn.makefile("r")
+        output = conn.makefile("w")
+
+        environ = self.read_env(input)
+        environ['wsgi.input']        = input
+        environ['wsgi.errors']       = sys.stderr
+        environ['wsgi.version']      = (1, 0)
+        environ['wsgi.multithread']  = False
+        environ['wsgi.multiprocess'] = True
+        environ['wsgi.run_once']     = False
+
+        # dunno how SCGI does HTTPS signalling; can't test it myself... @CTB
+        if environ.get('HTTPS','off') in ('on','1'):
+            environ['wsgi.url_scheme'] = 'https'
+        else:
+            environ['wsgi.url_scheme'] = 'http'
+
+        ## SCGI does some weird environ manglement.  We need to set
+        ## SCRIPT_NAME from 'prefix' and then set PATH_INFO from
+        ## REQUEST_URI.
+
+        prefix = self.prefix
+        path = environ['REQUEST_URI'][len(prefix):].split('?', 1)[0]
+
+        environ['SCRIPT_NAME'] = prefix
+        environ['PATH_INFO'] = path
+
+        headers_set = []
+        headers_sent = []
+        chunks = []
+        def write(data):
+            chunks.append(data)
+
+        def start_response(status, response_headers, exc_info=None):
+            if exc_info:
+                try:
+                    if headers_sent:
+                        # Re-raise original exception if headers sent
+                        six.reraise(exc_info[0], exc_info[1], exc_info[2])
+                finally:
+                    exc_info = None     # avoid dangling circular ref
+            elif headers_set:
+                raise AssertionError("Headers already set!")
+
+            headers_set[:] = [status, response_headers]
+            return write
+
+        ###
+
+        result = self.app_obj(environ, start_response)
+        try:
+            for data in result:
+                chunks.append(data)
+
+            # Before the first output, send the stored headers
+            if not headers_set:
+                # Error -- the app never called start_response
+                status = '500 Server Error'
+                response_headers = [('Content-type', 'text/html')]
+                chunks = ["XXX start_response never called"]
+            else:
+                status, response_headers = headers_sent[:] = headers_set
+
+            output.write('Status: %s\r\n' % status)
+            for header in response_headers:
+                output.write('%s: %s\r\n' % header)
+            output.write('\r\n')
+
+            for data in chunks:
+                output.write(data)
+        finally:
+            if hasattr(result,'close'):
+                result.close()
+
+        # SCGI backends use connection closing to signal 'fini'.
+        try:
+            input.close()
+            output.close()
+            conn.close()
+        except IOError as err:
+            debug("IOError while closing connection ignored: %s" % err)
+
+
+def serve_application(application, prefix, port=None, host=None, max_children=None):
+    """
+    Serve the specified WSGI application via SCGI proxy.
+
+    ``application``
+        The WSGI application to serve.
+
+    ``prefix``
+        The prefix for what is served by the SCGI Web-server-side process.
+
+    ``port``
+        Optional port to bind the SCGI proxy to. Defaults to SCGIServer's
+        default port value.
+
+    ``host``
+        Optional host to bind the SCGI proxy to. Defaults to SCGIServer's
+        default host value.
+
+    ``host``
+        Optional maximum number of child processes the SCGIServer will
+        spawn. Defaults to SCGIServer's default max_children value.
+    """
+    class SCGIAppHandler(SWAP):
+        def __init__ (self, *args, **kwargs):
+            self.prefix = prefix
+            self.app_obj = application
+            SWAP.__init__(self, *args, **kwargs)
+
+    kwargs = dict(handler_class=SCGIAppHandler)
+    for kwarg in ('host', 'port', 'max_children'):
+        if locals()[kwarg] is not None:
+            kwargs[kwarg] = locals()[kwarg]
+
+    scgi_server.SCGIServer(**kwargs).serve()