package dtls import ( "context" "github.com/pion/dtls/v2/pkg/crypto/prf" "github.com/pion/dtls/v2/pkg/protocol" "github.com/pion/dtls/v2/pkg/protocol/alert" "github.com/pion/dtls/v2/pkg/protocol/handshake" "github.com/pion/dtls/v2/pkg/protocol/recordlayer" ) func flight5bParse(ctx context.Context, c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) (flightVal, *alert.Alert, error) { _, msgs, ok := cache.fullPullMap(state.handshakeRecvSequence-1, handshakeCachePullRule{handshake.TypeFinished, cfg.initialEpoch + 1, false, false}, ) if !ok { // No valid message received. Keep reading return 0, nil, nil } if _, ok = msgs[handshake.TypeFinished].(*handshake.MessageFinished); !ok { return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, nil } // Other party may re-transmit the last flight. Keep state to be flight5b. return flight5b, nil, nil } func flight5bGenerate(c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) ([]*packet, *alert.Alert, error) { //nolint:gocognit var pkts []*packet pkts = append(pkts, &packet{ record: &recordlayer.RecordLayer{ Header: recordlayer.Header{ Version: protocol.Version1_2, }, Content: &protocol.ChangeCipherSpec{}, }, }) if len(state.localVerifyData) == 0 { plainText := cache.pullAndMerge( handshakeCachePullRule{handshake.TypeClientHello, cfg.initialEpoch, true, false}, handshakeCachePullRule{handshake.TypeServerHello, cfg.initialEpoch, false, false}, handshakeCachePullRule{handshake.TypeFinished, cfg.initialEpoch + 1, false, false}, ) var err error state.localVerifyData, err = prf.VerifyDataClient(state.masterSecret, plainText, state.cipherSuite.HashFunc()) if err != nil { return nil, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err } } pkts = append(pkts, &packet{ record: &recordlayer.RecordLayer{ Header: recordlayer.Header{ Version: protocol.Version1_2, Epoch: 1, }, Content: &handshake.Handshake{ Message: &handshake.MessageFinished{ VerifyData: state.localVerifyData, }, }, }, shouldEncrypt: true, resetLocalSequenceNumber: true, }) return pkts, nil, nil }