Added init message harness

docs/go-fuzz/lnwire/init/init.go

@@ -0,0 +1,69 @@
+// +build gofuzz
+
+package init
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"reflect"
+
+	"github.com/lightningnetwork/lnd/lnwire"
+)
+
+func Fuzz(data []byte) int {
+	// TODO - Since we prefix the data with 16 (the Init message prefix), should we
+	// remove the prefix from corpus/Init.txt?
+
+	// Prefix with MsgInit.
+	prefix := make([]byte, 2)
+	binary.BigEndian.PutUint16(prefix, uint16(lnwire.MsgInit))
+	data = append(prefix, data...)
+
+	// Create a reader with the byte array.
+	r := bytes.NewReader(data)
+
+	// Make sure byte array length (excluding 2 bytes for message type) is
+	// less than max payload size for the Init message. We check this because
+	// otherwise `go-fuzz` will keep creating inputs that crash on ReadMessage
+	// due to a large message size.
+	emptyMsg := lnwire.Init{}
+	payloadLen := uint32(len(data)) - 2
+	if payloadLen > emptyMsg.MaxPayloadLength(0) {
+		// Ignore this input - max payload constraint violated
+		return -1
+	}
+
+	msg, err := lnwire.ReadMessage(r, 0)
+	if err != nil {
+		// Ignore this input - go-fuzz generated []byte that cannot be
+		// represented as an Init message.
+		return -1
+	}
+
+	// We will serialize the Init message into a new bytes buffer.
+	var b bytes.Buffer
+	if _, err := lnwire.WriteMessage(&b, msg, 0); err != nil {
+		// Could not serialize Init message into bytes buffer, panic
+		panic(err)
+	}
+
+	// Deserialize the message from the serialized bytes buffer, and then
+	// assert that the original message is equal to the newly deserialized
+	// message.
+	newMsg, err := lnwire.ReadMessage(&b, 0)
+	if err != nil {
+		// Could not deserialize Init message from bytes buffer, panic
+		panic(err)
+	}
+
+	if !reflect.DeepEqual(msg, newMsg) {
+		// Deserialized Init message and original Init message are not
+		// deeply equal
+		panic(fmt.Errorf("Deserialized message and original message " +
+			"are not deeply equal."))
+	}
+
+	// Add this input to the corpus.
+	return 1
+}