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