[sans-io] tls: handle multiple servers

mitmproxy/proxy2/layers/http/http.py

@@ -601,6 +601,9 @@ class HTTPLayer(Layer):
                 self.connections[event.command.connection] = stream
             self.event_to_child(stream, event)
         elif isinstance(event, events.ConnectionEvent):
+            if event.connection == self.context.server and self.context.server not in self.connections:
+                pass
+            else:
                 handler = self.connections[event.connection]
                 self.event_to_child(handler, event)
         else:
@@ -624,6 +627,15 @@ class HTTPLayer(Layer):
             else:
                 raise ValueError(f"Unexpected event: {event}")
 
+    def make_stream(self) -> HttpStream:
+        ctx = self.context.fork()
+
+        stream = HttpStream(ctx)
+        if self.debug:
+            stream.debug = self.debug + "  "
+        self.event_to_child(stream, events.Start())
+        return stream
+
     def get_connection(self, event: GetHttpConnection):
         # Do we already have a connection we can re-use?
         for connection, handler in self.connections.items():
@@ -646,6 +658,7 @@ class HTTPLayer(Layer):
                 return
         # Can we reuse context.server?
         can_reuse_context_connection = (
+                self.context.server not in self.connections and
                 self.context.server.connected and
                 self.context.server.tls == event.tls
         )
@@ -661,15 +674,6 @@ class HTTPLayer(Layer):
             open_command.blocking = object()
             yield open_command
 
-    def make_stream(self) -> HttpStream:
-        ctx = self.context.fork()
-
-        stream = HttpStream(ctx)
-        if self.debug:
-            stream.debug = self.debug + "  "
-        self.event_to_child(stream, events.Start())
-        return stream
-
     def make_http_connection(self, connection: Server) -> None:
         if connection.tls and not connection.tls_established:
             new_command = EstablishServerTLS(connection)

mitmproxy/proxy2/layers/tls.py

@@ -1,6 +1,6 @@
 import os
 import struct
-from typing import Any, Generator, Iterator, Optional
+from typing import Any, Dict, Generator, Iterator, Optional, Tuple
 
 from OpenSSL import SSL
 
@@ -100,131 +100,154 @@ class EstablishServerTLSReply(events.CommandReply):
 
 
 class _TLSLayer(layer.Layer):
-    conn: Optional[context.Connection] = None
-    tls_conn: Optional[SSL.Connection] = None
+    tls: Dict[context.Connection, SSL.Connection]
     child_layer: layer.Layer
 
+    def __init__(self, context: context.Context):
+        super().__init__(context)
+        self.tls = {}
+
     def __repr__(self):
-        if self.conn is None:
+        if not self.tls:
             state = "inactive"
-        elif self.conn.tls_established:
-            state = f"passthrough {self.conn.sni}, {self.conn.alpn}"
         else:
-            state = f"negotiating {self.conn.sni}, {self.conn.alpn}"
+            conn_states = []
+            for conn in self.tls:
+                if conn.tls_established:
+                    conn_states.append(f"passthrough {conn.sni} {conn.alpn}")
+                else:
+                    conn_states.append(f"negotiating {conn.sni} {conn.alpn}")
+            state = ", ".join(conn_states)
         return f"{type(self).__name__}({state})"
 
-    def tls_interact(self):
+    def tls_interact(self, conn: context.Connection) -> commands.TCommandGenerator:
         while True:
             try:
-                data = self.tls_conn.bio_read(65535)
+                data = self.tls[conn].bio_read(65535)
             except SSL.WantReadError:
                 # Okay, nothing more waiting to be sent.
                 return
             else:
-                yield commands.SendData(self.conn, data)
+                yield commands.SendData(conn, data)
 
-    def negotiate(self, data: bytes) -> Generator[commands.Command, Any, bool]:
+    def negotiate(self, conn: context.Connection, data: bytes) -> Generator[
+        commands.Command, Any, Tuple[bool, Optional[str]]]:
         # bio_write errors for b"", so we need to check first if we actually received something.
         if data:
-            self.tls_conn.bio_write(data)
+            self.tls[conn].bio_write(data)
         try:
-            self.tls_conn.do_handshake()
+            self.tls[conn].do_handshake()
         except SSL.WantReadError:
-            yield from self.tls_interact()
-            return False
-        except SSL.ZeroReturnError:
-            raise  # TODO: Figure out what to do when handshake fails.
+            yield from self.tls_interact(conn)
+            return False, None
+        except SSL.ZeroReturnError as e:
+            return False, repr(e)
         else:
-            self.conn.tls_established = True
-            self.conn.alpn = self.tls_conn.get_alpn_proto_negotiated()
-            yield commands.Log(f"TLS established: {self.conn}")
-            yield from self.receive(b"")
+            conn.tls_established = True
+            conn.alpn = self.tls[conn].get_alpn_proto_negotiated()
+            yield commands.Log(f"TLS established: {conn}")
+            yield from self.receive(conn, b"")
             # TODO: Set all other connection attributes here
             # there might already be data in the OpenSSL BIO, so we need to trigger its processing.
-            return True
+            return True, None
 
-    def receive(self, data: bytes):
+    def receive(self, conn: context.Connection, data: bytes):
         if data:
-            self.tls_conn.bio_write(data)
-        yield from self.tls_interact()
+            self.tls[conn].bio_write(data)
+        yield from self.tls_interact(conn)
 
         plaintext = bytearray()
+        close = False
         while True:
             try:
-                plaintext.extend(self.tls_conn.recv(65535))
-            except (SSL.WantReadError, SSL.ZeroReturnError):
+                plaintext.extend(self.tls[conn].recv(65535))
+            except SSL.WantReadError:
+                break
+            except SSL.ZeroReturnError:
+                close = True
                 break
 
         if plaintext:
-            evt = events.DataReceived(self.conn, bytes(plaintext))
-            yield from self.event_to_child(evt)
+            yield from self.event_to_child(
+                events.DataReceived(conn, bytes(plaintext))
+            )
+        if close:
+            conn.state &= ~context.ConnectionState.CAN_READ
+            yield commands.Log(f"TLS close_notify {conn=}")
+            yield from self.event_to_child(
+                events.ConnectionClosed(conn)
+            )
 
     def event_to_child(self, event: events.Event) -> commands.TCommandGenerator:
         for command in self.child_layer.handle_event(event):
-            if isinstance(command, commands.SendData) and command.connection == self.conn:
-                self.tls_conn.sendall(command.data)
-                yield from self.tls_interact()
+            if isinstance(command, commands.SendData) and command.connection in self.tls:
+                self.tls[command.connection].sendall(command.data)
+                yield from self.tls_interact(command.connection)
             else:
                 yield command
 
     def _handle_event(self, event: events.Event) -> commands.TCommandGenerator:
-        if isinstance(event, events.DataReceived) and event.connection == self.conn:
-            if not self.conn.tls_established:
-                yield from self.negotiate(event.data)
+        if isinstance(event, events.DataReceived) and event.connection in self.tls:
+            if not event.connection.tls_established:
+                yield from self.negotiate(event.connection, event.data)
             else:
-                yield from self.receive(event.data)
+                yield from self.receive(event.connection, event.data)
+        elif (
+                isinstance(event, events.ConnectionClosed) and
+                event.connection in self.tls and
+                self.tls[event.connection].get_shutdown() & SSL.RECEIVED_SHUTDOWN
+        ):
+            pass  # We have already dispatched a ConnectionClosed to the child layer.
         else:
             yield from self.event_to_child(event)
 
 
 class ServerTLSLayer(_TLSLayer):
     """
-    This layer manages TLS for a single server connection.
+    This layer manages TLS for  potentially multiple server connections.
     """
-    command_to_reply_to: Optional[EstablishServerTLS] = None
+    command_to_reply_to: Dict[context.Connection, EstablishServerTLS]
 
     def __init__(self, context: context.Context):
         super().__init__(context)
+        self.command_to_reply_to = {}
         self.child_layer = layer.NextLayer(self.context)
 
-    def negotiate(self, data: bytes) -> Generator[commands.Command, Any, bool]:
-        done = yield from super().negotiate(data)
-        if done:
-            assert self.command_to_reply_to
-            yield from self.event_to_child(EstablishServerTLSReply(self.command_to_reply_to, None))
-            self.command_to_reply_to = None
-        return done
+    def negotiate(self, conn: context.Connection, data: bytes) -> Generator[
+        commands.Command, Any, Tuple[bool, Optional[str]]]:
+        done, err = yield from super().negotiate(conn, data)
+        if done or err:
+            cmd = self.command_to_reply_to.pop(conn)
+            yield from self.event_to_child(EstablishServerTLSReply(cmd, err))
+        return done, err
 
     def event_to_child(self, event: events.Event) -> commands.TCommandGenerator:
         for command in super().event_to_child(event):
             if isinstance(command, EstablishServerTLS):
-                assert isinstance(command.connection, context.Server)
-                assert not self.command_to_reply_to
-                self.command_to_reply_to = command
+                self.command_to_reply_to[command.connection] = command
                 yield from self.start_server_tls(command.connection)
             else:
                 yield command
 
-    def start_server_tls(self, server: context.Server):
+    def start_server_tls(self, conn: context.Server):
+        assert conn not in self.tls
+        assert conn.connected
+
         ssl_context = SSL.Context(SSL.SSLv23_METHOD)
-        if server.alpn_offers:
-            ssl_context.set_alpn_protos(server.alpn_offers)
+        if conn.alpn_offers:
+            ssl_context.set_alpn_protos(conn.alpn_offers)
+        self.tls[conn] = SSL.Connection(ssl_context)
 
-        assert not self.conn or not self.conn.connected
-        assert server.connected
-        self.conn = server
-        self.tls_conn = SSL.Connection(ssl_context)
-
-        if server.sni:
-            if server.sni is True:
+        if conn.sni:
+            if conn.sni is True:
                 if self.context.client.sni:
-                    server.sni = self.context.client.sni
+                    conn.sni = self.context.client.sni
                 else:
-                    server.sni = server.address[0]
-            self.tls_conn.set_tlsext_host_name(server.sni)
-        self.tls_conn.set_connect_state()
+                    conn.sni = conn.address[0].encode()
+            self.tls[conn].set_tlsext_host_name(conn.sni)
+        self.tls[conn].set_connect_state()
 
-        yield from self.negotiate(b"")
+        yield from self.negotiate(conn, b"")
 
 
 class ClientTLSLayer(_TLSLayer):
@@ -249,7 +272,6 @@ class ClientTLSLayer(_TLSLayer):
     def __init__(self, context: context.Context):
         assert isinstance(context.layers[-1], ServerTLSLayer)
         super().__init__(context)
-        self.conn = context.client
         self.recv_buffer = bytearray()
         self.child_layer = layer.NextLayer(self.context)
 
@@ -269,7 +291,7 @@ class ClientTLSLayer(_TLSLayer):
             try:
                 client_hello = parse_client_hello(self.recv_buffer)
             except ValueError as e:
-                raise NotImplementedError() from e  # TODO
+                raise NotImplementedError from e  # TODO
 
             if client_hello:
                 yield commands.Log(f"Client Hello: {client_hello}")
@@ -292,7 +314,8 @@ class ClientTLSLayer(_TLSLayer):
                 if client_tls_requires_server_connection and not self.context.server.tls_established:
                     err = yield from self.start_server_tls()
                     if err:
-                        raise NotImplementedError
+                        yield commands.Log("Unable to establish TLS connection with server. "
+                                           "Trying to establish TLS with client anyway.")
 
                 yield from self.start_client_tls()
                 self._handle_event = super()._handle_event
@@ -312,7 +335,7 @@ class ClientTLSLayer(_TLSLayer):
             err = yield commands.OpenConnection(server)
             if err:
                 yield commands.Log(
-                    "Cannot establish server connection, which is required to establish TLS with the client."
+                    f"Cannot establish server connection: {err}"
                 )
                 return err
 
@@ -324,11 +347,11 @@ class ClientTLSLayer(_TLSLayer):
         err = yield EstablishServerTLS(server)
         if err:
             yield commands.Log(
-                "Cannot establish TLS with server, which is required to establish TLS with the client."
+                f"Cannot establish TLS with server: {err}"
             )
             return err
 
-    def start_client_tls(self):
+    def start_client_tls(self) -> commands.TCommandGenerator:
         # FIXME: Do this properly. Also adjust error message in negotiate()
         client = self.context.client
         server = self.context.server
@@ -358,17 +381,15 @@ class ClientTLSLayer(_TLSLayer):
 
         context.set_alpn_select_callback(alpn_select_callback)
 
-        self.tls_conn = SSL.Connection(context)
-        self.tls_conn.set_accept_state()
+        self.tls[client] = SSL.Connection(context)
+        self.tls[client].set_accept_state()
 
-        yield from self.negotiate(bytes(self.recv_buffer))
-        self.recv_buffer = None
+        yield from self.negotiate(client, bytes(self.recv_buffer))
+        self.recv_buffer.clear()
 
-    def negotiate(self, data: bytes) -> Generator[commands.Command, Any, bool]:
-        try:
-            done = yield from super().negotiate(data)
-            return done
-        except SSL.ZeroReturnError:
+    def negotiate(self, conn: context.Connection, data: bytes) -> Generator[commands.Command, Any, bool]:
+        done, err = yield from super().negotiate(conn, data)
+        if err:
             yield commands.Log(
                 f"Client TLS Handshake failed. "
                 f"The client may not trust the proxy's certificate (SNI: {self.context.client.sni}).",
@@ -376,3 +397,4 @@ class ClientTLSLayer(_TLSLayer):
                 # TODO: Also use other sources than SNI
             )
             yield commands.CloseConnection(self.context.client)
+        return done

mitmproxy/proxy2/server.py

@@ -191,7 +191,7 @@ if __name__ == "__main__":
 
     opts = moptions.Options()
     opts.add_option(
-        "connection_strategy", str, "lazy",
+        "connection_strategy", str, "eager",
         "Determine when server connections should be established.",
         choices=("eager", "lazy")
     )
@@ -200,6 +200,7 @@ if __name__ == "__main__":
 
     async def handle(reader, writer):
         layer_stack = [
+            lambda ctx: layers.ServerTLSLayer(ctx),
             lambda ctx: layers.HTTPLayer(ctx, HTTPMode.regular),
             lambda ctx: setattr(ctx.server, "tls", True) or layers.ServerTLSLayer(ctx),
             lambda ctx: layers.ClientTLSLayer(ctx),