Add grpc local addr

The XHTTP inbound set every accepted connection's LocalAddr to the
listener's address (h.localAddr = l.listener.Addr()). On a wildcard
listener that is the unspecified address ("[::]" / "0.0.0.0").

sendThrough "origin" derives the outbound gateway from inbound.Local,
which comes from conn.LocalAddr(). So with XHTTP every connection's
egress was bound to the wildcard, collapsing all entry IPs onto one
(often IPv6) source address and breaking source-in-source-out on
multi-IP hosts (and failing outright when that address has no route).

Read the concrete per-connection local address from the request context
(http.LocalAddrContextKey), which net/http populates with the address
the client actually connected to. Fall back to the listener address when
the key is absent (e.g. HTTP/3, where net/http does not set it).

transport/internet/grpc/encoding/hunkconn.go

@@ -38,12 +38,14 @@ func NewHunkReadWriter(hc HunkConn, cancel context.CancelFunc) *HunkReaderWriter
 
 func NewHunkConn(hc HunkConn, cancel context.CancelFunc, trustedXForwardedFor []string) net.Conn {
 	rAddr := remoteAddrFromContext(hc.Context(), trustedXForwardedFor)
+	lAddr := localAddrFromContext(hc.Context())
 	wrc := NewHunkReadWriter(hc, cancel)
 	return cnc.NewConnection(
 		cnc.ConnectionInput(wrc),
 		cnc.ConnectionOutput(wrc),
 		cnc.ConnectionOnClose(wrc),
 		cnc.ConnectionRemoteAddr(rAddr),
+		cnc.ConnectionLocalAddr(lAddr),
 	)
 }
 

transport/internet/grpc/encoding/multiconn.go

@@ -33,12 +33,14 @@ func NewMultiHunkReadWriter(hc MultiHunkConn, cancel context.CancelFunc) *MultiH
 
 func NewMultiHunkConn(hc MultiHunkConn, cancel context.CancelFunc, trustedXForwardedFor []string) net.Conn {
 	rAddr := remoteAddrFromContext(hc.Context(), trustedXForwardedFor)
+	lAddr := localAddrFromContext(hc.Context())
 	wrc := NewMultiHunkReadWriter(hc, cancel)
 	return cnc.NewConnection(
 		cnc.ConnectionInputMulti(wrc),
 		cnc.ConnectionOutputMulti(wrc),
 		cnc.ConnectionOnClose(wrc),
 		cnc.ConnectionRemoteAddr(rAddr),
+		cnc.ConnectionLocalAddr(lAddr),
 	)
 }
 

transport/internet/grpc/encoding/remoteaddr.go

@@ -56,3 +56,17 @@ func parseTrustedXForwardedFor(md metadata.MD, trusted []string, remoteAddr net.
 	}
 	return nil
 }
+
+func localAddrFromContext(ctx context.Context) net.Addr {
+	var localAddr net.Addr
+	if pr, ok := peer.FromContext(ctx); ok {
+		localAddr = pr.LocalAddr
+	}
+	if localAddr == nil {
+		localAddr = &net.TCPAddr{
+			IP:   []byte{0, 0, 0, 0},
+			Port: 0,
+		}
+	}
+	return localAddr
+}

transport/internet/splithttp/hub.go

@@ -373,11 +373,15 @@ func (h *requestHandler) ServeHTTP(writer http.ResponseWriter, request *http.Req
 			Reader:         request.Body,
 			ResponseWriter: writer,
 		}
+		localAddr := h.localAddr
+		if la, ok := request.Context().Value(http.LocalAddrContextKey).(net.Addr); ok && la != nil {
+			localAddr = la
+		}
 		conn := splitConn{
 			writer:     httpSC,
 			reader:     httpSC,
 			remoteAddr: remoteAddr,
-			localAddr:  h.localAddr,
+			localAddr:  localAddr,
 		}
 		if sessionId != "" { // if not stream-one
 			conn.reader = currentSession.uploadQueue