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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package dtls
import (
"context"
"github.com/pion/dtls/v3/pkg/crypto/elliptic"
"github.com/pion/dtls/v3/pkg/protocol"
"github.com/pion/dtls/v3/pkg/protocol/alert"
"github.com/pion/dtls/v3/pkg/protocol/extension"
"github.com/pion/dtls/v3/pkg/protocol/handshake"
"github.com/pion/dtls/v3/pkg/protocol/recordlayer"
)
func flight1Parse(
ctx context.Context,
conn flightConn,
state *State,
cache *handshakeCache,
cfg *handshakeConfig,
) (flightVal, *alert.Alert, error) {
// HelloVerifyRequest can be skipped by the server,
// so allow ServerHello during flight1 also
seq, msgs, ok := cache.fullPullMap(state.handshakeRecvSequence, state.cipherSuite,
handshakeCachePullRule{handshake.TypeHelloVerifyRequest, cfg.initialEpoch, false, true},
handshakeCachePullRule{handshake.TypeServerHello, cfg.initialEpoch, false, true},
)
if !ok {
// No valid message received. Keep reading
return 0, nil, nil
}
if _, ok := msgs[handshake.TypeServerHello]; ok {
// Flight1 and flight2 were skipped.
// Parse as flight3.
return flight3Parse(ctx, conn, state, cache, cfg)
}
if h, ok := msgs[handshake.TypeHelloVerifyRequest].(*handshake.MessageHelloVerifyRequest); ok {
// DTLS 1.2 clients must not assume that the server will use the protocol version
// specified in HelloVerifyRequest message. RFC 6347 Section 4.2.1
if !h.Version.Equal(protocol.Version1_0) && !h.Version.Equal(protocol.Version1_2) {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.ProtocolVersion}, errUnsupportedProtocolVersion
}
state.cookie = append([]byte{}, h.Cookie...)
state.handshakeRecvSequence = seq
return flight3, nil, nil
}
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, nil
}
//nolint:cyclop
func flight1Generate(
conn flightConn,
state *State,
_ *handshakeCache,
cfg *handshakeConfig,
) ([]*packet, *alert.Alert, error) {
var zeroEpoch uint16
state.localEpoch.Store(zeroEpoch)
state.remoteEpoch.Store(zeroEpoch)
state.namedCurve = defaultNamedCurve
state.cookie = nil
if err := state.localRandom.Populate(); err != nil {
return nil, nil, err
}
if cfg.helloRandomBytesGenerator != nil {
state.localRandom.RandomBytes = cfg.helloRandomBytesGenerator()
}
extensions := []extension.Extension{
&extension.SupportedSignatureAlgorithms{
SignatureHashAlgorithms: cfg.localSignatureSchemes,
},
&extension.RenegotiationInfo{
RenegotiatedConnection: 0,
},
}
var setEllipticCurveCryptographyClientHelloExtensions bool
for _, c := range cfg.localCipherSuites {
if c.ECC() {
setEllipticCurveCryptographyClientHelloExtensions = true
break
}
}
if setEllipticCurveCryptographyClientHelloExtensions {
extensions = append(extensions, []extension.Extension{
&extension.SupportedEllipticCurves{
EllipticCurves: cfg.ellipticCurves,
},
&extension.SupportedPointFormats{
PointFormats: []elliptic.CurvePointFormat{elliptic.CurvePointFormatUncompressed},
},
}...)
}
if len(cfg.localSRTPProtectionProfiles) > 0 {
extensions = append(extensions, &extension.UseSRTP{
ProtectionProfiles: cfg.localSRTPProtectionProfiles,
MasterKeyIdentifier: cfg.localSRTPMasterKeyIdentifier,
})
}
if cfg.extendedMasterSecret == RequestExtendedMasterSecret ||
cfg.extendedMasterSecret == RequireExtendedMasterSecret {
extensions = append(extensions, &extension.UseExtendedMasterSecret{
Supported: true,
})
}
if len(cfg.serverName) > 0 {
extensions = append(extensions, &extension.ServerName{ServerName: cfg.serverName})
}
if len(cfg.supportedProtocols) > 0 {
extensions = append(extensions, &extension.ALPN{ProtocolNameList: cfg.supportedProtocols})
}
if cfg.sessionStore != nil {
cfg.log.Tracef("[handshake] try to resume session")
if s, err := cfg.sessionStore.Get(conn.sessionKey()); err != nil {
return nil, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
} else if s.ID != nil {
cfg.log.Tracef("[handshake] get saved session: %x", s.ID)
state.SessionID = s.ID
state.masterSecret = s.Secret
}
}
// If we have a connection ID generator, use it. The CID may be zero length,
// in which case we are just requesting that the server send us a CID to
// use.
if cfg.connectionIDGenerator != nil {
state.setLocalConnectionID(cfg.connectionIDGenerator())
// The presence of a generator indicates support for connection IDs. We
// use the presence of a non-nil local CID in flight 3 to determine
// whether we send a CID in the second ClientHello, so we convert any
// nil CID returned by a generator to []byte{}.
if state.getLocalConnectionID() == nil {
state.setLocalConnectionID([]byte{})
}
extensions = append(extensions, &extension.ConnectionID{CID: state.getLocalConnectionID()})
}
clientHello := &handshake.MessageClientHello{
Version: protocol.Version1_2,
SessionID: state.SessionID,
Cookie: state.cookie,
Random: state.localRandom,
CipherSuiteIDs: cipherSuiteIDs(cfg.localCipherSuites),
CompressionMethods: defaultCompressionMethods(),
Extensions: extensions,
}
var content handshake.Handshake
if cfg.clientHelloMessageHook != nil {
content = handshake.Handshake{Message: cfg.clientHelloMessageHook(*clientHello)}
} else {
content = handshake.Handshake{Message: clientHello}
}
return []*packet{
{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &content,
},
},
}, nil, nil
}
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