lnd.xprv/fuzz/brontide/random_actthree.go

// +build gofuzz

package brontidefuzz

import (
	"github.com/lightningnetwork/lnd/brontide"
)

// Fuzz_random_actthree is a go-fuzz harness for ActThree in the brontide
// handshake.
func Fuzz_random_actthree(data []byte) int {
	// Check if data is large enough.
	if len(data) < brontide.ActThreeSize {
		return 1
	}

	// This will return brontide machines with random keys.
	initiator, responder := getBrontideMachines()

	// Generate ActOne and send to the responder.
	actOne, err := initiator.GenActOne()
	if err != nil {
		nilAndPanic(initiator, responder, err)
	}

	// Receiving ActOne should succeed, so we panic on error.
	if err := responder.RecvActOne(actOne); err != nil {
		nilAndPanic(initiator, responder, err)
	}

	// Generate ActTwo - this is not sent to the initiator because nothing is
	// done with the initiator after this point and it would slow down fuzzing.
	// GenActTwo needs to be called to set the appropriate state in the
	// responder machine.
	_, err = responder.GenActTwo()
	if err != nil {
		nilAndPanic(initiator, responder, err)
	}

	// Copy data into [ActThreeSize]byte.
	var actThree [brontide.ActThreeSize]byte
	copy(actThree[:], data)

	// Responder receives ActThree, should fail on the MAC check.
	if err := responder.RecvActThree(actThree); err == nil {
		nilAndPanic(initiator, responder, nil)
	}

	return 1
}