lnd.xprv/docs/go-fuzz/wirefuzz.go
nsa 1e62865cf9 docs: fuzzing with go-fuzz tutorial
This commit adds a tutorial on fuzzing with the go-fuzz library
into the docs folder. It includes an introduction to fuzzing,
setup and installation steps to run go-fuzz with lnd, tips to
generate a valid corpus for use with go-fuzz, and finally it
includes a small explanation of the test harness that was used
to find bugs in lnd.
2017-10-05 18:28:59 -07:00

54 lines
1.6 KiB
Go

package wirefuzz
import (
"bytes"
"fmt"
"github.com/lightningnetwork/lnd/lnwire"
"reflect"
)
// Fuzz is used by go-fuzz to fuzz for potentially malicious input
func Fuzz(data []byte) int {
// Because go-fuzz requires this function signature with a []byte parameter,
// and we want to emulate the behavior of mainScenario in lnwire_test.go,
// we first parse the []byte parameter into a Message type.
// Parsing []byte into Message
r := bytes.NewReader(data)
msg, err := lnwire.ReadMessage(r, 0)
if err != nil {
// Ignore this input - go-fuzz generated []byte that cannot be represented as Message
return 0
}
// We will serialize Message into a new bytes buffer
var b bytes.Buffer
if _, err := lnwire.WriteMessage(&b, msg, 0); err != nil {
// Could not serialize Message into bytes buffer, panic
panic(err)
}
// Make sure serialized bytes buffer (excluding 2 bytes for message type
// is less than max payload size for this specific message,.
payloadLen := uint32(b.Len()) - 2
if payloadLen > msg.MaxPayloadLength(0) {
// Ignore this input - max payload constraint violated
return 0
}
// Deserialize the message from the serialized bytes buffer and
// assert that the original message is equal to the newly deserialized message.
newMsg, err := lnwire.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."))
}
return 1
}