snapshot of https://github.com/nats-io/nats-server.git (main, 2026-09-15; blobs > 131072B omitted)

server/parser_fuzz_test.go

@@ -0,0 +1,98 @@
+// Copyright 2025-2026 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package server
+
+import (
+	"sync"
+	"testing"
+)
+
+func dummyFuzzClient(kind int) *client {
+	var r *route
+	var gw *gateway
+	var lf *leaf
+
+	switch kind {
+	case ROUTER:
+		r = &route{}
+	case GATEWAY:
+		gw = &gateway{outbound: false, connected: true, insim: make(map[string]*insie), outsim: &sync.Map{}}
+	case LEAF:
+		lf = &leaf{}
+	}
+
+	return &client{
+		srv: func() *Server {
+			opts := defaultServerOptions
+			return New(&opts)
+		}(),
+		kind:  kind,
+		msubs: -1,
+		in: readCache{
+			results: make(map[string]*SublistResult),
+			pacache: make(map[string]*perAccountCache),
+		},
+		mpay:  MAX_PAYLOAD_SIZE,
+		mcl:   MAX_CONTROL_LINE_SIZE,
+		route: r,
+		gw:    gw,
+		leaf:  lf,
+	}
+}
+
+// FuzzParser performs fuzz testing on the NATS protocol parser implementation.
+// It tests the parser's ability to handle various NATS protocol messages, including
+// partial (chunked) message delivery scenarios that may occur in real-world usage.
+func FuzzParser(f *testing.F) {
+	msgs := []string{
+		"PING\r\n",
+		"PONG\r\n",
+		"PUB foo 33333\r\n",
+		"HPUB foo INBOX.22 0 5\r\nHELLO\r",
+		"HMSG $foo foo 10 8\r\nXXXhello\r",
+		"MSG $foo foo 5\r\nhello\r",
+		"SUB foo 1\r\nSUB foo 2\r\n",
+		"UNSUB 1 5\r\n",
+		"RMSG $G foo.bar | baz 11\r\nhello world\r",
+		"CONNECT {\"verbose\":false,\"pedantic\":true,\"tls_required\":false}\r\n",
+	}
+
+	clientKinds := []int{
+		CLIENT,
+		ROUTER,
+		GATEWAY,
+		LEAF,
+	}
+
+	for _, ck := range clientKinds {
+		for _, crp := range msgs {
+			f.Add(ck, crp)
+		}
+	}
+
+	f.Fuzz(func(t *testing.T, kind int, orig string) {
+		c := dummyFuzzClient(kind)
+
+		data := []byte(orig)
+		half := len(data) / 2
+
+		if err := c.parse(data[:half]); err != nil {
+			return
+		}
+
+		if err := c.parse(data[half:]); err != nil {
+			return
+		}
+	})
+}