fuzz/wtwire: adding wtwire fuzzers

fuzz/wtwire/create_session.go

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+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_create_session is used by go-fuzz.
+func Fuzz_create_session(data []byte) int {
+	// Prefix with MsgCreateSession.
+	data = prefixWithMsgType(data, wtwire.MsgCreateSession)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.CreateSession{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/create_session_reply.go

@@ -0,0 +1,20 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_create_session_reply is used by go-fuzz.
+func Fuzz_create_session_reply(data []byte) int {
+	// Prefix with MsgCreateSessionReply.
+	data = prefixWithMsgType(data, wtwire.MsgCreateSessionReply)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.CreateSessionReply{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/delete_session.go

@@ -0,0 +1,20 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_delete_session is used by go-fuzz.
+func Fuzz_delete_session(data []byte) int {
+	// Prefix with MsgDeleteSession.
+	data = prefixWithMsgType(data, wtwire.MsgDeleteSession)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.DeleteSession{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/delete_session_reply.go

@@ -0,0 +1,20 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_delete_session_reply is used by go-fuzz.
+func Fuzz_delete_session_reply(data []byte) int {
+	// Prefix with MsgDeleteSessionReply.
+	data = prefixWithMsgType(data, wtwire.MsgDeleteSessionReply)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.DeleteSessionReply{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/error.go

@@ -0,0 +1,20 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_error is used by go-fuzz.
+func Fuzz_error(data []byte) int {
+	// Prefix with MsgError.
+	data = prefixWithMsgType(data, wtwire.MsgError)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.Error{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/fuzz_utils.go

@@ -0,0 +1,75 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"reflect"
+
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// prefixWithMsgType takes []byte and adds a wire protocol prefix
+// to make the []byte into an actual message to be used in fuzzing.
+func prefixWithMsgType(data []byte, prefix wtwire.MessageType) []byte {
+	var prefixBytes [2]byte
+	binary.BigEndian.PutUint16(prefixBytes[:], uint16(prefix))
+	data = append(prefixBytes[:], data...)
+	return data
+}
+
+// harness performs the actual fuzz testing of the appropriate wire message.
+// This function will check that the passed-in message passes wire length checks,
+// is a valid message once deserialized, and passes a sequence of serialization
+// and deserialization checks. Returns an int that determines whether the input
+// is unique or not.
+func harness(data []byte, emptyMsg wtwire.Message) int {
+	// 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 wire message. We check this because
+	// otherwise `go-fuzz` will keep creating inputs that crash on ReadMessage
+	// due to a large message size.
+	payloadLen := uint32(len(data)) - 2
+	if payloadLen > emptyMsg.MaxPayloadLength(0) {
+		// Ignore this input - max payload constraint violated.
+		return -1
+	}
+
+	msg, err := wtwire.ReadMessage(r, 0)
+	if err != nil {
+		// go-fuzz generated []byte that cannot be represented as a
+		// wire message but we will return 0 so go-fuzz can modify the
+		// input.
+		return 0
+	}
+
+	// We will serialize the message into a new bytes buffer.
+	var b bytes.Buffer
+	if _, err := wtwire.WriteMessage(&b, msg, 0); err != nil {
+		// Could not serialize 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 := wtwire.ReadMessage(&b, 0)
+	if err != nil {
+		// Could not deserialize message from bytes buffer, panic.
+		panic(err)
+	}
+
+	if !reflect.DeepEqual(msg, newMsg) {
+		// Deserialized message and original 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
+}

fuzz/wtwire/init.go

@@ -0,0 +1,20 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_init is used by go-fuzz.
+func Fuzz_init(data []byte) int {
+	// Prefix with MsgInit.
+	data = prefixWithMsgType(data, wtwire.MsgInit)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.Init{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/state_update.go

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+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_state_update is used by go-fuzz.
+func Fuzz_state_update(data []byte) int {
+	// Prefix with MsgStateUpdate.
+	data = prefixWithMsgType(data, wtwire.MsgStateUpdate)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.StateUpdate{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}

fuzz/wtwire/state_update_reply.go

@@ -0,0 +1,20 @@
+// +build gofuzz
+
+package wtwirefuzz
+
+import (
+	"github.com/lightningnetwork/lnd/watchtower/wtwire"
+)
+
+// Fuzz_state_update_reply is used by go-fuzz.
+func Fuzz_state_update_reply(data []byte) int {
+	// Prefix with MsgStateUpdateReply.
+	data = prefixWithMsgType(data, wtwire.MsgStateUpdateReply)
+
+	// Create an empty message so that the FuzzHarness func can check if the
+	// max payload constraint is violated.
+	emptyMsg := wtwire.StateUpdateReply{}
+
+	// Pass the message into our general fuzz harness for wire messages!
+	return harness(data, &emptyMsg)
+}