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|
package dtls
import (
"context"
"github.com/pion/dtls/v2/pkg/crypto/elliptic"
"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/extension"
"github.com/pion/dtls/v2/pkg/protocol/handshake"
"github.com/pion/dtls/v2/pkg/protocol/recordlayer"
)
func flight3Parse(ctx context.Context, c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) (flightVal, *alert.Alert, error) { //nolint:gocognit
// Clients may receive multiple HelloVerifyRequest messages with different cookies.
// Clients SHOULD handle this by sending a new ClientHello with a cookie in response
// to the new HelloVerifyRequest. RFC 6347 Section 4.2.1
seq, msgs, ok := cache.fullPullMap(state.handshakeRecvSequence,
handshakeCachePullRule{handshake.TypeHelloVerifyRequest, cfg.initialEpoch, false, true},
)
if ok {
if h, msgOk := msgs[handshake.TypeHelloVerifyRequest].(*handshake.MessageHelloVerifyRequest); msgOk {
// 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
}
}
if cfg.localPSKCallback != nil {
seq, msgs, ok = cache.fullPullMap(state.handshakeRecvSequence,
handshakeCachePullRule{handshake.TypeServerHello, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeServerKeyExchange, cfg.initialEpoch, false, true},
handshakeCachePullRule{handshake.TypeServerHelloDone, cfg.initialEpoch, false, false},
)
} else {
seq, msgs, ok = cache.fullPullMap(state.handshakeRecvSequence,
handshakeCachePullRule{handshake.TypeServerHello, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeCertificate, cfg.initialEpoch, false, true},
handshakeCachePullRule{handshake.TypeServerKeyExchange, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeCertificateRequest, cfg.initialEpoch, false, true},
handshakeCachePullRule{handshake.TypeServerHelloDone, cfg.initialEpoch, false, false},
)
}
if !ok {
// Don't have enough messages. Keep reading
return 0, nil, nil
}
state.handshakeRecvSequence = seq
if h, ok := msgs[handshake.TypeServerHello].(*handshake.MessageServerHello); ok {
if !h.Version.Equal(protocol.Version1_2) {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.ProtocolVersion}, errUnsupportedProtocolVersion
}
for _, v := range h.Extensions {
switch e := v.(type) {
case *extension.UseSRTP:
profile, ok := findMatchingSRTPProfile(e.ProtectionProfiles, cfg.localSRTPProtectionProfiles)
if !ok {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.IllegalParameter}, errClientNoMatchingSRTPProfile
}
state.srtpProtectionProfile = profile
case *extension.UseExtendedMasterSecret:
if cfg.extendedMasterSecret != DisableExtendedMasterSecret {
state.extendedMasterSecret = true
}
}
}
if cfg.extendedMasterSecret == RequireExtendedMasterSecret && !state.extendedMasterSecret {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errClientRequiredButNoServerEMS
}
if len(cfg.localSRTPProtectionProfiles) > 0 && state.srtpProtectionProfile == 0 {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errRequestedButNoSRTPExtension
}
remoteCipherSuite := cipherSuiteForID(CipherSuiteID(*h.CipherSuiteID), cfg.customCipherSuites)
if remoteCipherSuite == nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errCipherSuiteNoIntersection
}
selectedCipherSuite, ok := findMatchingCipherSuite([]CipherSuite{remoteCipherSuite}, cfg.localCipherSuites)
if !ok {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errInvalidCipherSuite
}
state.cipherSuite = selectedCipherSuite
state.remoteRandom = h.Random
cfg.log.Tracef("[handshake] use cipher suite: %s", selectedCipherSuite.String())
}
if h, ok := msgs[handshake.TypeCertificate].(*handshake.MessageCertificate); ok {
state.PeerCertificates = h.Certificate
} else if state.cipherSuite.AuthenticationType() == CipherSuiteAuthenticationTypeCertificate {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.NoCertificate}, errInvalidCertificate
}
if h, ok := msgs[handshake.TypeServerKeyExchange].(*handshake.MessageServerKeyExchange); ok {
alertPtr, err := handleServerKeyExchange(c, state, cfg, h)
if err != nil {
return 0, alertPtr, err
}
}
if _, ok := msgs[handshake.TypeCertificateRequest].(*handshake.MessageCertificateRequest); ok {
state.remoteRequestedCertificate = true
}
return flight5, nil, nil
}
func handleServerKeyExchange(_ flightConn, state *State, cfg *handshakeConfig, h *handshake.MessageServerKeyExchange) (*alert.Alert, error) {
var err error
if cfg.localPSKCallback != nil {
var psk []byte
if psk, err = cfg.localPSKCallback(h.IdentityHint); err != nil {
return &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
state.IdentityHint = h.IdentityHint
state.preMasterSecret = prf.PSKPreMasterSecret(psk)
} else {
if state.localKeypair, err = elliptic.GenerateKeypair(h.NamedCurve); err != nil {
return &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
if state.preMasterSecret, err = prf.PreMasterSecret(h.PublicKey, state.localKeypair.PrivateKey, state.localKeypair.Curve); err != nil {
return &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
}
return nil, nil
}
func flight3Generate(c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) ([]*packet, *alert.Alert, error) {
extensions := []extension.Extension{
&extension.SupportedSignatureAlgorithms{
SignatureHashAlgorithms: cfg.localSignatureSchemes,
},
&extension.RenegotiationInfo{
RenegotiatedConnection: 0,
},
}
if cfg.localPSKCallback == nil {
extensions = append(extensions, []extension.Extension{
&extension.SupportedEllipticCurves{
EllipticCurves: []elliptic.Curve{elliptic.X25519, elliptic.P256, elliptic.P384},
},
&extension.SupportedPointFormats{
PointFormats: []elliptic.CurvePointFormat{elliptic.CurvePointFormatUncompressed},
},
}...)
}
if len(cfg.localSRTPProtectionProfiles) > 0 {
extensions = append(extensions, &extension.UseSRTP{
ProtectionProfiles: cfg.localSRTPProtectionProfiles,
})
}
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})
}
return []*packet{
{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: &handshake.MessageClientHello{
Version: protocol.Version1_2,
Cookie: state.cookie,
Random: state.localRandom,
CipherSuiteIDs: cipherSuiteIDs(cfg.localCipherSuites),
CompressionMethods: defaultCompressionMethods(),
Extensions: extensions,
},
},
},
},
}, nil, nil
}
|
