mirror of https://github.com/status-im/go-waku.git
108 lines
2.9 KiB
Go
108 lines
2.9 KiB
Go
package relay
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import (
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"context"
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"crypto/ecdsa"
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"crypto/elliptic"
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"encoding/binary"
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"encoding/hex"
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"time"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/secp256k1"
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pubsub "github.com/libp2p/go-libp2p-pubsub"
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"github.com/libp2p/go-libp2p/core/peer"
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"github.com/waku-org/go-waku/waku/v2/hash"
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"github.com/waku-org/go-waku/waku/v2/protocol/pb"
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"github.com/waku-org/go-waku/waku/v2/timesource"
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"go.uber.org/zap"
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proto "google.golang.org/protobuf/proto"
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)
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func msgHash(pubSubTopic string, msg *pb.WakuMessage) []byte {
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timestampBytes := make([]byte, 8)
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binary.LittleEndian.PutUint64(timestampBytes, uint64(msg.Timestamp))
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var ephemeralByte byte
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if msg.Ephemeral {
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ephemeralByte = 1
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}
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return hash.SHA256(
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[]byte(pubSubTopic),
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msg.Payload,
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[]byte(msg.ContentTopic),
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timestampBytes,
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[]byte{ephemeralByte},
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)
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}
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const messageWindowDuration = time.Minute * 5
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func withinTimeWindow(t timesource.Timesource, msg *pb.WakuMessage) bool {
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if msg.Timestamp == 0 {
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return false
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}
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now := t.Now()
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msgTime := time.Unix(0, msg.Timestamp)
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return now.Sub(msgTime).Abs() <= messageWindowDuration
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}
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type validatorFn = func(ctx context.Context, peerID peer.ID, message *pubsub.Message) bool
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func validatorFnBuilder(t timesource.Timesource, topic string, publicKey *ecdsa.PublicKey) (validatorFn, error) {
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publicKeyBytes := crypto.FromECDSAPub(publicKey)
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return func(ctx context.Context, peerID peer.ID, message *pubsub.Message) bool {
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msg := new(pb.WakuMessage)
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err := proto.Unmarshal(message.Data, msg)
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if err != nil {
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return false
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}
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if !withinTimeWindow(t, msg) {
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return false
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}
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msgHash := msgHash(topic, msg)
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signature := msg.Meta
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return secp256k1.VerifySignature(publicKeyBytes, msgHash, signature)
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}, nil
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}
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// AddSignedTopicValidator registers a gossipsub validator for a topic which will check that messages Meta field contains a valid ECDSA signature for the specified pubsub topic. This is used as a DoS prevention mechanism
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func (w *WakuRelay) AddSignedTopicValidator(topic string, publicKey *ecdsa.PublicKey) error {
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w.log.Info("adding validator to signed topic", zap.String("topic", topic), zap.String("publicKey", hex.EncodeToString(elliptic.Marshal(publicKey.Curve, publicKey.X, publicKey.Y))))
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fn, err := validatorFnBuilder(w.timesource, topic, publicKey)
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if err != nil {
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return err
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}
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err = w.pubsub.RegisterTopicValidator(topic, fn)
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if err != nil {
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return err
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}
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if !w.IsSubscribed(topic) {
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w.log.Warn("relay is not subscribed to signed topic", zap.String("topic", topic))
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}
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return nil
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}
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// SignMessage adds an ECDSA signature to a WakuMessage as an opt-in mechanism for DoS prevention
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func SignMessage(privKey *ecdsa.PrivateKey, msg *pb.WakuMessage, pubsubTopic string) error {
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msgHash := msgHash(pubsubTopic, msg)
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sign, err := secp256k1.Sign(msgHash, crypto.FromECDSA(privKey))
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if err != nil {
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return err
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}
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msg.Meta = sign[0:64] // Remove V
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return nil
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}
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