package dtls import ( "bytes" "context" "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 flight2Parse(ctx context.Context, c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) (flightVal, *alert.Alert, error) { seq, msgs, ok := cache.fullPullMap(state.handshakeRecvSequence, handshakeCachePullRule{handshake.TypeClientHello, cfg.initialEpoch, true, false}, ) if !ok { // Client may retransmit the first ClientHello when HelloVerifyRequest is dropped. // Parse as flight 0 in this case. return flight0Parse(ctx, c, state, cache, cfg) } state.handshakeRecvSequence = seq var clientHello *handshake.MessageClientHello // Validate type if clientHello, ok = msgs[handshake.TypeClientHello].(*handshake.MessageClientHello); !ok { return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, nil } if !clientHello.Version.Equal(protocol.Version1_2) { return 0, &alert.Alert{Level: alert.Fatal, Description: alert.ProtocolVersion}, errUnsupportedProtocolVersion } if len(clientHello.Cookie) == 0 { return 0, nil, nil } if !bytes.Equal(state.cookie, clientHello.Cookie) { return 0, &alert.Alert{Level: alert.Fatal, Description: alert.AccessDenied}, errCookieMismatch } return flight4, nil, nil } func flight2Generate(c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) ([]*packet, *alert.Alert, error) { state.handshakeSendSequence = 0 return []*packet{ { record: &recordlayer.RecordLayer{ Header: recordlayer.Header{ Version: protocol.Version1_2, }, Content: &handshake.Handshake{ Message: &handshake.MessageHelloVerifyRequest{ Version: protocol.Version1_2, Cookie: state.cookie, }, }, }, }, }, nil, nil }