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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package dtls
import (
"context"
"crypto/rand"
"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"
)
//nolint:cyclop
func flight0Parse(
_ context.Context,
_ flightConn,
state *State,
cache *handshakeCache,
cfg *handshakeConfig,
) (flightVal, *alert.Alert, error) {
seq, msgs, ok := cache.fullPullMap(0, state.cipherSuite,
handshakeCachePullRule{handshake.TypeClientHello, cfg.initialEpoch, true, false},
)
if !ok {
// No valid message received. Keep reading
return 0, nil, nil
}
// Connection Identifiers must be negotiated afresh on session resumption.
// https://datatracker.ietf.org/doc/html/rfc9146#name-the-connection_id-extension
state.setLocalConnectionID(nil)
state.remoteConnectionID = nil
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
}
state.remoteRandom = clientHello.Random
cipherSuites := []CipherSuite{}
for _, id := range clientHello.CipherSuiteIDs {
if c := cipherSuiteForID(CipherSuiteID(id), cfg.customCipherSuites); c != nil {
cipherSuites = append(cipherSuites, c)
}
}
if state.cipherSuite, ok = findMatchingCipherSuite(cipherSuites, cfg.localCipherSuites); !ok {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errCipherSuiteNoIntersection
}
for _, val := range clientHello.Extensions {
switch ext := val.(type) {
case *extension.SupportedEllipticCurves:
if len(ext.EllipticCurves) == 0 {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errNoSupportedEllipticCurves
}
state.namedCurve = ext.EllipticCurves[0]
case *extension.UseSRTP:
profile, ok := findMatchingSRTPProfile(ext.ProtectionProfiles, cfg.localSRTPProtectionProfiles)
if !ok {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errServerNoMatchingSRTPProfile
}
state.setSRTPProtectionProfile(profile)
state.remoteSRTPMasterKeyIdentifier = ext.MasterKeyIdentifier
case *extension.UseExtendedMasterSecret:
if cfg.extendedMasterSecret != DisableExtendedMasterSecret {
state.extendedMasterSecret = true
}
case *extension.ServerName:
state.serverName = ext.ServerName // remote server name
case *extension.RenegotiationInfo:
state.remoteSupportsRenegotiation = true
case *extension.ALPN:
state.peerSupportedProtocols = ext.ProtocolNameList
case *extension.ConnectionID:
// Only set connection ID to be sent if server supports connection
// IDs.
if cfg.connectionIDGenerator != nil {
state.remoteConnectionID = ext.CID
}
}
}
// If the client doesn't support connection IDs, the server should not
// expect one to be sent.
if state.remoteConnectionID == nil {
state.setLocalConnectionID(nil)
}
if cfg.extendedMasterSecret == RequireExtendedMasterSecret && !state.extendedMasterSecret {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errServerRequiredButNoClientEMS
}
if state.localKeypair == nil {
var err error
state.localKeypair, err = elliptic.GenerateKeypair(state.namedCurve)
if err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.IllegalParameter}, err
}
}
nextFlight := flight2
if cfg.insecureSkipHelloVerify {
nextFlight = flight4
}
return handleHelloResume(clientHello.SessionID, state, cfg, nextFlight)
}
func handleHelloResume(
sessionID []byte,
state *State,
cfg *handshakeConfig,
next flightVal,
) (flightVal, *alert.Alert, error) {
if len(sessionID) > 0 && cfg.sessionStore != nil {
if s, err := cfg.sessionStore.Get(sessionID); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
} else if s.ID != nil {
cfg.log.Tracef("[handshake] resume session: %x", sessionID)
state.SessionID = sessionID
state.masterSecret = s.Secret
if err := state.initCipherSuite(); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
clientRandom := state.localRandom.MarshalFixed()
cfg.writeKeyLog(keyLogLabelTLS12, clientRandom[:], state.masterSecret)
return flight4b, nil, nil
}
}
return next, nil, nil
}
func flight0Generate(
_ flightConn,
state *State,
_ *handshakeCache,
cfg *handshakeConfig,
) ([]*packet, *alert.Alert, error) {
// Initialize
if !cfg.insecureSkipHelloVerify {
state.cookie = make([]byte, cookieLength)
if _, err := rand.Read(state.cookie); err != nil {
return nil, nil, err
}
}
var zeroEpoch uint16
state.localEpoch.Store(zeroEpoch)
state.remoteEpoch.Store(zeroEpoch)
state.namedCurve = defaultNamedCurve
if err := state.localRandom.Populate(); err != nil {
return nil, nil, err
}
return nil, nil, nil
}
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