Expose ErrDetermineNetworkType

Expose this error so pion/webrtc can handle gracefully.
rfc8839#section-5.1 specifies that a WebRTC Agent MUST
ignore any name/value pairs it doesn't understand.

Relates to pion/webrtc#1949

candidate_test.go

@@ -307,6 +307,7 @@ func TestCandidateMarshal(t *testing.T) {
 		{nil, "4207374051 1 udp INVALID 10.0.75.1 53634 typ host", true},
 		{nil, "4207374051 INVALID udp 2130706431 10.0.75.1 INVALID typ host", true},
 		{nil, "4207374051 1 udp 2130706431 10.0.75.1 53634 typ INVALID", true},
+		{nil, "4207374051 1 INVALID 2130706431 10.0.75.1 53634 typ host", true},
 	} {
 		actualCandidate, err := UnmarshalCandidate(test.marshaled)
 		if test.expectError {

errors.go

@@ -112,6 +112,9 @@ var (
 	// ErrUnknownCandidateTyp indicates that a candidate had a unknown type value.
 	ErrUnknownCandidateTyp = errors.New("unknown candidate typ")
 
+	// ErrDetermineNetworkType indicates that the NetworkType was not able to be parsed
+	ErrDetermineNetworkType = errors.New("unable to determine networkType")
+
 	errSendPacket                    = errors.New("failed to send packet")
 	errAttributeTooShortICECandidate = errors.New("attribute not long enough to be ICE candidate")
 	errParseComponent                = errors.New("could not parse component")
@@ -124,7 +127,6 @@ var (
 	errReadingStreamingPacket        = errors.New("error reading streaming packet")
 	errWriting                       = errors.New("error writing to")
 	errClosingConnection             = errors.New("error closing connection")
-	errDetermineNetworkType          = errors.New("unable to determine networkType")
 	errMissingProtocolScheme         = errors.New("missing protocol scheme")
 	errTooManyColonsAddr             = errors.New("too many colons in address")
 	errRead                          = errors.New("unexpected error trying to read")

networktype.go

@@ -126,5 +126,5 @@ func determineNetworkType(network string, ip net.IP) (NetworkType, error) {
 		return NetworkTypeTCP6, nil
 	}
 
-	return NetworkType(0), fmt.Errorf("%w from %s %s", errDetermineNetworkType, network, ip)
+	return NetworkType(0), fmt.Errorf("%w from %s %s", ErrDetermineNetworkType, network, ip)
 }