添加 github.com/pion/dtls 代码

dtls-2.0.9/flight1handler.go

@@ -0,0 +1,112 @@
+package dtls
+
+import (
+	"context"
+
+	"github.com/pion/dtls/v2/pkg/crypto/elliptic"
+	"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 flight1Parse(ctx context.Context, c 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,
+		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, c, 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
+}
+
+func flight1Generate(c flightConn, state *State, cache *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
+	}
+
+	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
+}