Fixed logic error; multi host chicken and egg finger printing causes hosts to never join

internal/transport/rpc.go

@@ -107,7 +107,10 @@ func (s *Server) handleConn(ctx context.Context, raw net.Conn) {
 	if err := tlsConn.HandshakeContext(ctx); err != nil {
 		return
 	}
-	peerID := peerNodeIDFromConnState(tlsConn.ConnectionState())
+	state := tlsConn.ConnectionState()
+	peerID := peerNodeIDFromConnState(state)
+	peerFP := peerFingerprintFromConnState(state)
+	trusted := s.peerTrusted(peerFP)
 
 	for {
 		body, err := readFrame(tlsConn)
@@ -120,6 +123,14 @@ func (s *Server) handleConn(ctx context.Context, raw net.Conn) {
 			return
 		}
 
+		// Until the peer is trusted, only the bootstrap call (Join) is
+		// allowed through. Everything else gets a clear error so the
+		// caller knows to re-run `qu node add`.
+		if !trusted && req.Method != MethodJoin {
+			_ = writeError(tlsConn, req.ID, "peer not trusted; run `qu node add` first")
+			continue
+		}
+
 		fn, exists := s.handlers[req.Method]
 		if !exists {
 			_ = writeError(tlsConn, req.ID, "unknown method: "+req.Method)
@@ -134,9 +145,26 @@ func (s *Server) handleConn(ctx context.Context, raw net.Conn) {
 		if err := writeResult(tlsConn, req.ID, result); err != nil {
 			return
 		}
+
+		// A successful Join writes the caller into our trust store;
+		// re-check so subsequent calls on this same connection (or
+		// after reconnect) flow through normally.
+		if req.Method == MethodJoin && !trusted {
+			trusted = s.peerTrusted(peerFP)
+		}
 	}
 }
 
+// peerTrusted reports whether peerFP is in our trust store. Returns
+// false on empty input so a missing/parse-failed cert is never trusted.
+func (s *Server) peerTrusted(peerFP string) bool {
+	if peerFP == "" {
+		return false
+	}
+	_, ok := s.assets.Trust.LookupByFingerprint(peerFP)
+	return ok
+}
+
 // Client opens and pools one mTLS connection per peer node ID. Each
 // connection serialises outstanding calls under a mutex; concurrent
 // calls to different peers proceed in parallel.
@@ -321,3 +349,13 @@ func peerNodeIDFromConnState(cs tls.ConnectionState) string {
 	}
 	return cs.PeerCertificates[0].Subject.CommonName
 }
+
+// peerFingerprintFromConnState computes the SPKI fingerprint of the
+// peer's leaf cert, matching the format the trust store stores. An
+// empty result means the peer presented no cert.
+func peerFingerprintFromConnState(cs tls.ConnectionState) string {
+	if len(cs.PeerCertificates) == 0 {
+		return ""
+	}
+	return fingerprintOf(cs.PeerCertificates[0])
+}

internal/transport/rpc_test.go

@@ -170,6 +170,73 @@ func TestRPCRejectsUntrustedPeer(t *testing.T) {
 	}
 }
 
+func TestJoinAllowedFromUntrustedPeer(t *testing.T) {
+	// Verifies the bootstrap path: B has not yet been added to A's
+	// trust store. A must still accept the Join RPC; subsequent
+	// non-Join calls on the same connection should succeed once Join
+	// has populated trust.
+	a := makeNode(t, t.TempDir(), "node-a")
+	b := makeNode(t, t.TempDir(), "node-b")
+
+	tmpLn, _ := net.Listen("tcp", "127.0.0.1:0")
+	addr := tmpLn.Addr().String()
+	tmpLn.Close()
+
+	// B must trust A so B's client-side handshake passes.
+	t.Setenv("QUPTIME_DIR", b.dir)
+	_ = b.assets.Trust.Add(trust.Entry{NodeID: a.id, Address: addr, Fingerprint: a.fp})
+
+	srv := NewServer(a.assets)
+	srv.Handle(MethodJoin, func(_ context.Context, _ string, raw json.RawMessage) (any, error) {
+		var req JoinRequest
+		if err := json.Unmarshal(raw, &req); err != nil {
+			return JoinResponse{Error: err.Error()}, nil
+		}
+		// A pretends to accept and records B in its trust store.
+		t.Setenv("QUPTIME_DIR", a.dir)
+		if err := a.assets.Trust.Add(trust.Entry{
+			NodeID: req.NodeID, Address: req.Advertise, Fingerprint: req.Fingerprint,
+		}); err != nil {
+			return JoinResponse{Error: err.Error()}, nil
+		}
+		return JoinResponse{Accepted: true}, nil
+	})
+	srv.Handle(MethodPing, func(_ context.Context, _ string, _ json.RawMessage) (any, error) {
+		return PingResponse{NodeID: a.id, Now: time.Now()}, nil
+	})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	go srv.Serve(ctx, addr)
+	defer srv.Stop()
+	if !waitForDial(addr, 2*time.Second) {
+		t.Fatal("server not up")
+	}
+
+	cli := NewClient(b.assets)
+	defer cli.Close()
+
+	// Pre-Join: Ping must be rejected with the "not trusted" error.
+	if err := cli.Call(ctx, a.id, addr, MethodPing, nil, nil); err == nil {
+		t.Error("Ping was allowed without prior trust")
+	}
+
+	// Join must succeed even though B is untrusted.
+	joinReq := JoinRequest{NodeID: b.id, Advertise: addr, Fingerprint: b.fp, CertPEM: string(b.assets.Cert)}
+	var joinResp JoinResponse
+	if err := cli.Call(ctx, a.id, addr, MethodJoin, joinReq, &joinResp); err != nil {
+		t.Fatalf("Join: %v", err)
+	}
+	if !joinResp.Accepted {
+		t.Fatalf("Join not accepted: %s", joinResp.Error)
+	}
+
+	// Post-Join on the SAME pooled connection: Ping should now flow.
+	if err := cli.Call(ctx, a.id, addr, MethodPing, nil, nil); err != nil {
+		t.Errorf("post-Join Ping failed: %v", err)
+	}
+}
+
 // waitForDial polls a TCP listener until it accepts a plain TCP
 // connection, signalling that Serve has begun listening.
 func waitForDial(addr string, max time.Duration) bool {

internal/transport/tls.go

@@ -41,19 +41,24 @@ func (a *TLSAssets) tlsCert() (tls.Certificate, error) {
 }
 
 // ServerConfig produces a tls.Config suitable for an inter-node
-// listener. Peers must present a certificate, and that certificate's
-// fingerprint must already be present in the trust store.
+// listener.
+//
+// We accept any client certificate at the TLS layer (no CA verification
+// and no fingerprint pinning here). Trust is enforced one layer up by
+// the RPC dispatcher: untrusted peers may only invoke MethodJoin, which
+// is the protocol's bootstrap step. This avoids the chicken-and-egg
+// where Join itself would need pre-existing symmetric trust to complete
+// the handshake.
 func (a *TLSAssets) ServerConfig() (*tls.Config, error) {
 	cert, err := a.tlsCert()
 	if err != nil {
 		return nil, err
 	}
 	return &tls.Config{
-		Certificates:          []tls.Certificate{cert},
-		MinVersion:            MinTLS,
-		ClientAuth:            tls.RequireAnyClientCert,
-		InsecureSkipVerify:    true, // we do our own pinning via VerifyPeerCertificate
-		VerifyPeerCertificate: a.Trust.VerifyPeerCert,
+		Certificates:       []tls.Certificate{cert},
+		MinVersion:         MinTLS,
+		ClientAuth:         tls.RequireAnyClientCert,
+		InsecureSkipVerify: true, // trust is gated per-method by the RPC dispatcher
 	}, nil
 }