Move server framework from asyncio to socketserver

jetforce.py

@@ -35,7 +35,6 @@ StaticDirectoryApplication:
 from __future__ import annotations
 
 import argparse
-import asyncio
 import codecs
 import dataclasses
 import datetime
@@ -44,6 +43,7 @@ import os
 import pathlib
 import re
 import socket
+import socketserver
 import ssl
 import subprocess
 import sys
@@ -453,7 +453,7 @@ class StaticDirectoryApplication(JetforceApplication):
 
     def load_file(self, filesystem_path: pathlib.Path) -> typing.Iterator[bytes]:
         """
-        Load a file using a generator to allow streaming data to the TCP socket.
+        Load a file in chunks to allow streaming to the TCP socket.
         """
         with filesystem_path.open("rb") as fp:
             data = fp.read(1024)
@@ -514,7 +514,7 @@ class StaticDirectoryApplication(JetforceApplication):
             return Response(Status.NOT_FOUND, "Not Found")
 
 
-class GeminiRequestHandler:
+class GeminiRequestHandler(socketserver.StreamRequestHandler):
     """
     Handle a single Gemini Protocol TCP request.
 
@@ -534,55 +534,40 @@ class GeminiRequestHandler:
 
     TIMESTAMP_FORMAT = "%d/%b/%Y:%H:%M:%S %z"
 
-    reader: asyncio.StreamReader
-    writer: asyncio.StreamWriter
+    server: GeminiServer
     received_timestamp: time.struct_time
-    remote_addr: str
-    client_cert: dict
     url: str
     status: int
     meta: str
     response_buffer: str
     response_size: int
 
-    def __init__(self, server: GeminiServer, app: typing.Callable) -> None:
-        self.server = server
-        self.app = app
+    def setup(self) -> None:
         self.response_size = 0
+        self.response_buffer = ""
+        super().setup()
 
-    async def handle(
-        self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter
-    ) -> None:
+    def handle(self) -> None:
         """
-        Main method for the request handler, performs the following:
-
-            1. Read the request bytes from the reader stream
-            2. Parse the request and generate response data
-            3. Write the response bytes to the writer stream
+        The request handler entry point, called once for each connection.
         """
-        self.reader = reader
-        self.writer = writer
-        self.remote_addr = writer.get_extra_info("peername")[0]
-        self.client_cert = writer.get_extra_info("peercert")
         self.received_timestamp = time.localtime()
+        self.request.do_handshake()
 
         try:
-            await self.parse_header()
+            self.parse_header()
         except Exception:
             # Malformed request, throw it away and exit immediately
             self.write_status(Status.BAD_REQUEST, "Malformed request")
-            return await self.close_connection()
+            return
 
         try:
             environ = self.build_environ()
-            app = self.app(environ, self.write_status)
-            for data in app:
-                await self.write_body(data)
+            response_generator = self.server.app(environ, self.write_status)
+            for data in response_generator:
+                self.write_body(data)
         except Exception:
             self.write_status(Status.CGI_ERROR, "An unexpected error occurred")
-            raise
-        finally:
-            await self.close_connection()
 
     def build_environ(self) -> typing.Dict[str, typing.Any]:
         """
@@ -591,41 +576,43 @@ class GeminiRequestHandler:
         Variable names conform to the CGI spec defined in RFC 3875.
         """
         url_parts = urllib.parse.urlparse(self.url)
+        remote_addr, remote_port, *_ = self.client_address
         environ = {
             "GEMINI_URL": self.url,
             "HOSTNAME": self.server.hostname,
             "PATH_INFO": url_parts.path,
             "QUERY_STRING": url_parts.query,
-            "REMOTE_ADDR": self.remote_addr,
-            "REMOTE_HOST": self.remote_addr,
+            "REMOTE_ADDR": remote_addr,
+            "REMOTE_HOST": remote_addr,
             "SERVER_NAME": self.server.hostname,
-            "SERVER_PORT": str(self.server.port),
+            "SERVER_PORT": str(remote_port),
             "SERVER_PROTOCOL": "GEMINI",
             "SERVER_SOFTWARE": f"jetforce/{__version__}",
         }
 
-        if self.client_cert:
-            subject = dict(x[0] for x in self.client_cert["subject"])
+        client_cert = self.request.getpeercert()
+        if client_cert:
+            subject = dict(x[0] for x in client_cert["subject"])
             environ.update(
                 {
                     "AUTH_TYPE": "CERTIFICATE",
                     "REMOTE_USER": subject.get("commonName", ""),
-                    "TLS_CLIENT_NOT_BEFORE": self.client_cert["notBefore"],
-                    "TLS_CLIENT_NOT_AFTER": self.client_cert["notAfter"],
-                    "TLS_CLIENT_SERIAL_NUMBER": self.client_cert["serialNumber"],
+                    "TLS_CLIENT_NOT_BEFORE": client_cert["notBefore"],
+                    "TLS_CLIENT_NOT_AFTER": client_cert["notAfter"],
+                    "TLS_CLIENT_SERIAL_NUMBER": client_cert["serialNumber"],
                 }
             )
 
         return environ
 
-    async def parse_header(self) -> None:
+    def parse_header(self) -> None:
         """
         Parse the gemini header line.
 
         The request is a single UTF-8 line formatted as: <URL>\r\n
         """
-        data = await self.reader.readuntil(b"\r\n")
-        data = data[:-2]  # strip the line ending
+        data = self.rfile.readline(1026)
+        data = data.rstrip(b"\r\n")
         if len(data) > 1024:
             raise ValueError("URL exceeds max length of 1024 bytes")
 
@@ -650,53 +637,48 @@ class GeminiRequestHandler:
         self.meta = meta
         self.response_buffer = f"{status}\t{meta}\r\n"
 
-    async def write_body(self, data: bytes) -> None:
+    def write_body(self, data: bytes) -> None:
         """
         Write bytes to the gemini response body.
         """
-        await self.flush_status()
+        self.flush_status()
         self.response_size += len(data)
-        self.writer.write(data)
-        await self.writer.drain()
+        self.wfile.write(data)
 
-    async def flush_status(self) -> None:
+    def flush_status(self) -> None:
         """
         Flush the status line from the internal buffer to the socket stream.
         """
         if self.response_buffer and not self.response_size:
             data = self.response_buffer.encode()
             self.response_size += len(data)
-            self.writer.write(data)
-            await self.writer.drain()
+            self.wfile.write(data)
         self.response_buffer = ""
 
-    async def close_connection(self) -> None:
-        """
-        Flush any remaining bytes and close the stream.
-        """
-        await self.flush_status()
+    def finish(self) -> None:
+        self.flush_status()
+        try:
             self.log_request()
-        await self.writer.drain()
+        except AttributeError:
+            # Malformed request or dropped connection
+            pass
+        super().finish()
 
     def log_request(self) -> None:
         """
         Log a gemini request using a format derived from the Common Log Format.
         """
-        try:
         self.server.log_message(
-                f"{self.remote_addr} "
+            f"{self.client_address[0]} "
             f"[{time.strftime(self.TIMESTAMP_FORMAT, self.received_timestamp)}] "
             f'"{self.url}" '
             f"{self.status} "
             f'"{self.meta}" '
             f"{self.response_size}"
         )
-        except AttributeError:
-            # Malformed request or dropped connection
-            pass
 
 
-class GeminiServer:
+class GeminiServer(socketserver.ThreadingTCPServer):
     """
     An asynchronous TCP server that uses the asyncio stream abstraction.
 
@@ -715,47 +697,46 @@ class GeminiServer:
         hostname: str = "localhost",
     ) -> None:
 
-        self.host = host
-        self.port = port
-        self.hostname = hostname
         self.app = app
+        self.hostname = hostname
         self.ssl_context = ssl_context
+        super().__init__((host, port), self.request_handler_class, False)
 
-    async def run(self) -> None:
+    def run(self) -> None:
         """
-        The main asynchronous server loop.
+        Launch the main server loop.
         """
         self.log_message(ABOUT)
-        server = await asyncio.start_server(
-            self.accept_connection, self.host, self.port, ssl=self.ssl_context
-        )
-
         self.log_message(f"Server hostname is {self.hostname}")
-        for sock in server.sockets:
-            sock_ip, sock_port, *_ = sock.getsockname()
-            if sock.family == socket.AF_INET:
+        try:
+            self.server_bind()
+            self.server_activate()
+        except Exception:
+            self.server_close()
+            raise
+
+        sock_ip, sock_port, *_ = self.server_address
+        if self.address_family == socket.AF_INET:
             self.log_message(f"Listening on {sock_ip}:{sock_port}")
         else:
             self.log_message(f"Listening on [{sock_ip}]:{sock_port}")
 
-        async with server:
-            await server.serve_forever()
+        self.serve_forever()
 
-    async def accept_connection(
-        self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter
-    ) -> None:
+    def get_request(self):
         """
-        Hook called by the socket server when a new connection is accepted.
+        Wrap the incoming request in an SSL connection.
         """
-        request_handler = self.request_handler_class(self, self.app)
-        try:
-            await request_handler.handle(reader, writer)
-        finally:
-            writer.close()
+        # noinspection PyTupleAssignmentBalance
+        sock, client_addr = super(GeminiServer, self).get_request()
+        ssl_sock = self.ssl_context.wrap_socket(
+            sock, server_side=True, do_handshake_on_connect=False
+        )
+        return ssl_sock, client_addr
 
     def log_message(self, message: str) -> None:
         """
-        Log a diagnostic server message.
+        Log a diagnostic server message to stderr, may be overridden.
         """
         print(message, file=sys.stderr)
 
@@ -852,7 +833,7 @@ def run_server() -> None:
         args.hostname, args.certfile, args.keyfile, args.cafile, args.capath
     )
     server = GeminiServer(app, args.host, args.port, ssl_context, args.hostname)
-    asyncio.run(server.run())
+    server.run()
 
 
 if __name__ == "__main__":