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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package dtls
import (
"bytes"
"context"
"github.com/pion/dtls/v3/pkg/protocol"
"github.com/pion/dtls/v3/pkg/protocol/alert"
"github.com/pion/dtls/v3/pkg/protocol/handshake"
"github.com/pion/dtls/v3/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, state.cipherSuite,
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(
_ flightConn,
state *State,
_ *handshakeCache,
_ *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
}
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