1 files changed, 99 insertions, 0 deletions
diff --git a/vendor/git.torproject.org/pluggable-transports/snowflake.git/common/util/util.go b/vendor/git.torproject.org/pluggable-transports/snowflake.git/common/util/util.go
new file mode 100644
index 0000000..00f7302
--- /dev/null
+++ b/vendor/git.torproject.org/pluggable-transports/snowflake.git/common/util/util.go
@@ -0,0 +1,99 @@
+package util
+
+import (
+	"encoding/json"
+	"errors"
+	"net"
+
+	"github.com/pion/ice/v2"
+	"github.com/pion/sdp/v3"
+	"github.com/pion/webrtc/v3"
+)
+
+func SerializeSessionDescription(desc *webrtc.SessionDescription) (string, error) {
+	bytes, err := json.Marshal(*desc)
+	if err != nil {
+		return "", err
+	}
+	return string(bytes), nil
+}
+
+func DeserializeSessionDescription(msg string) (*webrtc.SessionDescription, error) {
+	var parsed map[string]interface{}
+	err := json.Unmarshal([]byte(msg), &parsed)
+	if err != nil {
+		return nil, err
+	}
+	if _, ok := parsed["type"]; !ok {
+		return nil, errors.New("cannot deserialize SessionDescription without type field")
+	}
+	if _, ok := parsed["sdp"]; !ok {
+		return nil, errors.New("cannot deserialize SessionDescription without sdp field")
+	}
+
+	var stype webrtc.SDPType
+	switch parsed["type"].(string) {
+	default:
+		return nil, errors.New("Unknown SDP type")
+	case "offer":
+		stype = webrtc.SDPTypeOffer
+	case "pranswer":
+		stype = webrtc.SDPTypePranswer
+	case "answer":
+		stype = webrtc.SDPTypeAnswer
+	case "rollback":
+		stype = webrtc.SDPTypeRollback
+	}
+
+	return &webrtc.SessionDescription{
+		Type: stype,
+		SDP:  parsed["sdp"].(string),
+	}, nil
+}
+
+// Stolen from https://github.com/golang/go/pull/30278
+func IsLocal(ip net.IP) bool {
+	if ip4 := ip.To4(); ip4 != nil {
+		// Local IPv4 addresses are defined in https://tools.ietf.org/html/rfc1918
+		return ip4[0] == 10 ||
+			(ip4[0] == 172 && ip4[1]&0xf0 == 16) ||
+			(ip4[0] == 192 && ip4[1] == 168) ||
+			// Carrier-Grade NAT as per https://tools.ietf.org/htm/rfc6598
+			(ip4[0] == 100 && ip4[1]&0xc0 == 64) ||
+			// Dynamic Configuration as per https://tools.ietf.org/htm/rfc3927
+			(ip4[0] == 169 && ip4[1] == 254)
+	}
+	// Local IPv6 addresses are defined in https://tools.ietf.org/html/rfc4193
+	return len(ip) == net.IPv6len && ip[0]&0xfe == 0xfc
+}
+
+// Removes local LAN address ICE candidates
+func StripLocalAddresses(str string) string {
+	var desc sdp.SessionDescription
+	err := desc.Unmarshal([]byte(str))
+	if err != nil {
+		return str
+	}
+	for _, m := range desc.MediaDescriptions {
+		attrs := make([]sdp.Attribute, 0)
+		for _, a := range m.Attributes {
+			if a.IsICECandidate() {
+				c, err := ice.UnmarshalCandidate(a.Value)
+				if err == nil && c.Type() == ice.CandidateTypeHost {
+					ip := net.ParseIP(c.Address())
+					if ip != nil && (IsLocal(ip) || ip.IsUnspecified() || ip.IsLoopback()) {
+						/* no append in this case */
+						continue
+					}
+				}
+			}
+			attrs = append(attrs, a)
+		}
+		m.Attributes = attrs
+	}
+	bts, err := desc.Marshal()
+	if err != nil {
+		return str
+	}
+	return string(bts)
+}