cleanup sdp

sdp/sdp.go

@@ -2,6 +2,12 @@
 package sdp
 
 import (
+	"errors"
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+
 	psdp "github.com/pion/sdp/v3"
 )
 
@@ -12,3 +18,620 @@ type SessionDescription psdp.SessionDescription
 func (s *SessionDescription) Marshal() ([]byte, error) {
 	return (*psdp.SessionDescription)(s).Marshal()
 }
+
+var (
+	errSDPInvalidSyntax       = errors.New("sdp: invalid syntax")
+	errSDPInvalidNumericValue = errors.New("sdp: invalid numeric value")
+	errSDPInvalidValue        = errors.New("sdp: invalid value")
+	errSDPInvalidPortValue    = errors.New("sdp: invalid port value")
+)
+
+func indexOf(element string, data []string) int {
+	for k, v := range data {
+		if element == v {
+			return k
+		}
+	}
+	return -1
+}
+
+func parsePort(value string) (int, error) {
+	port, err := strconv.Atoi(value)
+	if err != nil {
+		return 0, fmt.Errorf("%w `%v`", errSDPInvalidPortValue, port)
+	}
+
+	if port < 0 || port > 65536 {
+		return 0, fmt.Errorf("%w -- out of range `%v`", errSDPInvalidPortValue, port)
+	}
+
+	return port, nil
+}
+
+func (s *SessionDescription) unmarshalVersion(value string) error {
+	if value != "0" {
+		return fmt.Errorf("invalid version")
+	}
+	return nil
+}
+
+func (s *SessionDescription) unmarshalSessionName(value string) error {
+	s.SessionName = psdp.SessionName(value)
+	return nil
+}
+
+func (s *SessionDescription) unmarshalOrigin(value string) error {
+	// special case for live reporter app
+	if value[:3] == "-0 " {
+		value = "- 0 " + value[3:]
+	}
+
+	// special case for sone onvif2 cameras
+	if value[len(value)-1] == ' ' {
+		value += "127.0.0.1"
+	}
+
+	fields := strings.Fields(value)
+	if len(fields) != 6 {
+		return fmt.Errorf("%w `o=%v`", errSDPInvalidSyntax, fields)
+	}
+
+	sessionID, err := strconv.ParseUint(fields[1], 10, 64)
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[1])
+	}
+
+	sessionVersion, err := strconv.ParseUint(fields[2], 10, 64)
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[2])
+	}
+
+	// Set according to currently registered with IANA
+	// https://tools.ietf.org/html/rfc4566#section-8.2.6
+	if i := indexOf(fields[3], []string{"IN"}); i == -1 {
+		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[3])
+	}
+
+	// Set according to currently registered with IANA
+	// https://tools.ietf.org/html/rfc4566#section-8.2.7
+	if i := indexOf(fields[4], []string{"IP4", "IP6"}); i == -1 {
+		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[3])
+	}
+
+	s.Origin = psdp.Origin{
+		Username:       fields[0],
+		SessionID:      sessionID,
+		SessionVersion: sessionVersion,
+		NetworkType:    fields[3],
+		AddressType:    fields[4],
+		UnicastAddress: fields[5],
+	}
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalSessionInformation(value string) error {
+	sessionInformation := psdp.Information(value)
+	s.SessionInformation = &sessionInformation
+	return nil
+}
+
+func (s *SessionDescription) unmarshalURI(value string) error {
+	var err error
+	s.URI, err = url.Parse(value)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalEmail(value string) error {
+	emailAddress := psdp.EmailAddress(value)
+	s.EmailAddress = &emailAddress
+	return nil
+}
+
+func (s *SessionDescription) unmarshalPhone(value string) error {
+	phoneNumber := psdp.PhoneNumber(value)
+	s.PhoneNumber = &phoneNumber
+	return nil
+}
+
+func unmarshalConnectionInformation(value string) (*psdp.ConnectionInformation, error) {
+	fields := strings.Fields(value)
+	if len(fields) < 2 {
+		return nil, fmt.Errorf("%w `c=%v`", errSDPInvalidSyntax, fields)
+	}
+
+	// Set according to currently registered with IANA
+	// https://tools.ietf.org/html/rfc4566#section-8.2.6
+	if i := indexOf(fields[0], []string{"IN"}); i == -1 {
+		return nil, fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[0])
+	}
+
+	// Set according to currently registered with IANA
+	// https://tools.ietf.org/html/rfc4566#section-8.2.7
+	if i := indexOf(fields[1], []string{"IP4", "IP6"}); i == -1 {
+		return nil, fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[1])
+	}
+
+	connAddr := new(psdp.Address)
+	if len(fields) > 2 {
+		connAddr.Address = fields[2]
+	}
+
+	return &psdp.ConnectionInformation{
+		NetworkType: fields[0],
+		AddressType: fields[1],
+		Address:     connAddr,
+	}, nil
+}
+
+func (s *SessionDescription) unmarshalSessionConnectionInformation(value string) error {
+	var err error
+	s.ConnectionInformation, err = unmarshalConnectionInformation(value)
+	if err != nil {
+		return fmt.Errorf("%w `c=%v`", errSDPInvalidSyntax, value)
+	}
+	return nil
+}
+
+func unmarshalBandwidth(value string) (*psdp.Bandwidth, error) {
+	parts := strings.Split(value, ":")
+	if len(parts) != 2 {
+		return nil, fmt.Errorf("%w `b=%v`", errSDPInvalidValue, parts)
+	}
+
+	experimental := strings.HasPrefix(parts[0], "X-")
+	if experimental {
+		parts[0] = strings.TrimPrefix(parts[0], "X-")
+	} else if i := indexOf(parts[0], []string{"CT", "AS", "RR"}); i == -1 {
+		// Set according to currently registered with IANA
+		// https://tools.ietf.org/html/rfc4566#section-5.8
+		return nil, fmt.Errorf("%w `%v`", errSDPInvalidValue, parts[0])
+	}
+
+	bandwidth, err := strconv.ParseUint(parts[1], 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, parts[1])
+	}
+
+	return &psdp.Bandwidth{
+		Experimental: experimental,
+		Type:         parts[0],
+		Bandwidth:    bandwidth,
+	}, nil
+}
+
+func (s *SessionDescription) unmarshalSessionBandwidth(value string) error {
+	bandwidth, err := unmarshalBandwidth(value)
+	if err != nil {
+		return fmt.Errorf("%w `b=%v`", errSDPInvalidValue, value)
+	}
+	s.Bandwidth = append(s.Bandwidth, *bandwidth)
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalTimeZones(value string) error {
+	// These fields are transimitted in pairs
+	// z=<adjustment time> <offset> <adjustment time> <offset> ....
+	// so we are making sure that there are actually multiple of 2 total.
+	fields := strings.Fields(value)
+	if len(fields)%2 != 0 {
+		return fmt.Errorf("%w `t=%v`", errSDPInvalidSyntax, fields)
+	}
+
+	for i := 0; i < len(fields); i += 2 {
+		var timeZone psdp.TimeZone
+
+		var err error
+		timeZone.AdjustmentTime, err = strconv.ParseUint(fields[i], 10, 64)
+		if err != nil {
+			return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
+		}
+
+		timeZone.Offset, err = parseTimeUnits(fields[i+1])
+		if err != nil {
+			return err
+		}
+
+		s.TimeZones = append(s.TimeZones, timeZone)
+	}
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalSessionEncryptionKey(value string) error {
+	encryptionKey := psdp.EncryptionKey(value)
+	s.EncryptionKey = &encryptionKey
+	return nil
+}
+
+func (s *SessionDescription) unmarshalSessionAttribute(value string) error {
+	i := strings.IndexRune(value, ':')
+	var a psdp.Attribute
+	if i > 0 {
+		a = psdp.NewAttribute(value[:i], value[i+1:])
+	} else {
+		a = psdp.NewPropertyAttribute(value)
+	}
+
+	s.Attributes = append(s.Attributes, a)
+	return nil
+}
+
+func (s *SessionDescription) unmarshalTiming(value string) error {
+	fields := strings.Fields(value)
+	if len(fields) < 2 {
+		return fmt.Errorf("%w `t=%v`", errSDPInvalidSyntax, fields)
+	}
+
+	td := psdp.TimeDescription{}
+
+	var err error
+	td.Timing.StartTime, err = strconv.ParseUint(fields[0], 10, 64)
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[1])
+	}
+
+	td.Timing.StopTime, err = strconv.ParseUint(fields[1], 10, 64)
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[1])
+	}
+
+	s.TimeDescriptions = append(s.TimeDescriptions, td)
+
+	return nil
+}
+
+func parseTimeUnits(value string) (int64, error) {
+	// Some time offsets in the protocol can be provided with a shorthand
+	// notation. This code ensures to convert it to NTP timestamp format.
+	//      d - days (86400 seconds)
+	//      h - hours (3600 seconds)
+	//      m - minutes (60 seconds)
+	//      s - seconds (allowed for completeness)
+	switch value[len(value)-1:] {
+	case "d":
+		num, err := strconv.ParseInt(value[:len(value)-1], 10, 64)
+		if err != nil {
+			return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
+		}
+		return num * 86400, nil
+	case "h":
+		num, err := strconv.ParseInt(value[:len(value)-1], 10, 64)
+		if err != nil {
+			return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
+		}
+		return num * 3600, nil
+	case "m":
+		num, err := strconv.ParseInt(value[:len(value)-1], 10, 64)
+		if err != nil {
+			return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
+		}
+		return num * 60, nil
+	}
+
+	num, err := strconv.ParseInt(value, 10, 64)
+	if err != nil {
+		return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
+	}
+
+	return num, nil
+}
+
+func (s *SessionDescription) unmarshalRepeatTimes(value string) error {
+	fields := strings.Fields(value)
+	if len(fields) < 3 {
+		return fmt.Errorf("%w `r=%v`", errSDPInvalidSyntax, fields)
+	}
+
+	latestTimeDesc := &s.TimeDescriptions[len(s.TimeDescriptions)-1]
+
+	newRepeatTime := psdp.RepeatTime{}
+	var err error
+	newRepeatTime.Interval, err = parseTimeUnits(fields[0])
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
+	}
+
+	newRepeatTime.Duration, err = parseTimeUnits(fields[1])
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
+	}
+
+	for i := 2; i < len(fields); i++ {
+		offset, err := parseTimeUnits(fields[i])
+		if err != nil {
+			return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
+		}
+		newRepeatTime.Offsets = append(newRepeatTime.Offsets, offset)
+	}
+	latestTimeDesc.RepeatTimes = append(latestTimeDesc.RepeatTimes, newRepeatTime)
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalMediaDescription(value string) error {
+	fields := strings.Fields(value)
+	if len(fields) < 4 {
+		return fmt.Errorf("%w `m=%v`", errSDPInvalidSyntax, fields)
+	}
+
+	newMediaDesc := &psdp.MediaDescription{}
+
+	// <media>
+	// Set according to currently registered with IANA
+	// https://tools.ietf.org/html/rfc4566#section-5.14
+	if i := indexOf(fields[0], []string{"audio", "video", "text", "application", "message"}); i == -1 {
+		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[0])
+	}
+	newMediaDesc.MediaName.Media = fields[0]
+
+	// <port>
+	parts := strings.Split(fields[1], "/")
+	var err error
+	newMediaDesc.MediaName.Port.Value, err = parsePort(parts[0])
+	if err != nil {
+		return fmt.Errorf("%w `%v`", errSDPInvalidPortValue, parts[0])
+	}
+
+	if len(parts) > 1 {
+		portRange, err := strconv.Atoi(parts[1])
+		if err != nil {
+			return fmt.Errorf("%w `%v`", errSDPInvalidValue, parts)
+		}
+		newMediaDesc.MediaName.Port.Range = &portRange
+	}
+
+	// <proto>
+	// Set according to currently registered with IANA
+	// https://tools.ietf.org/html/rfc4566#section-5.14
+	for _, proto := range strings.Split(fields[2], "/") {
+		if i := indexOf(proto, []string{"UDP", "RTP", "AVP", "SAVP", "SAVPF",
+			"MP2T", "TLS", "DTLS", "SCTP", "AVPF", "TCP"}); i == -1 {
+			return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[2])
+		}
+		newMediaDesc.MediaName.Protos = append(newMediaDesc.MediaName.Protos, proto)
+	}
+
+	// <fmt>...
+	for i := 3; i < len(fields); i++ {
+		newMediaDesc.MediaName.Formats = append(newMediaDesc.MediaName.Formats, fields[i])
+	}
+
+	s.MediaDescriptions = append(s.MediaDescriptions, newMediaDesc)
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalMediaTitle(value string) error {
+	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
+	mediaTitle := psdp.Information(value)
+	latestMediaDesc.MediaTitle = &mediaTitle
+	return nil
+}
+
+func (s *SessionDescription) unmarshalMediaConnectionInformation(value string) error {
+	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
+	var err error
+	latestMediaDesc.ConnectionInformation, err = unmarshalConnectionInformation(value)
+	if err != nil {
+		return fmt.Errorf("%w `c=%v`", errSDPInvalidSyntax, value)
+	}
+
+	return nil
+}
+
+func (s *SessionDescription) unmarshalMediaBandwidth(value string) error {
+	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
+	bandwidth, err := unmarshalBandwidth(value)
+	if err != nil {
+		return fmt.Errorf("%w `b=%v`", errSDPInvalidSyntax, value)
+	}
+	latestMediaDesc.Bandwidth = append(latestMediaDesc.Bandwidth, *bandwidth)
+	return nil
+}
+
+func (s *SessionDescription) unmarshalMediaEncryptionKey(value string) error {
+	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
+	encryptionKey := psdp.EncryptionKey(value)
+	latestMediaDesc.EncryptionKey = &encryptionKey
+	return nil
+}
+
+func (s *SessionDescription) unmarshalMediaAttribute(value string) error {
+	i := strings.IndexRune(value, ':')
+	var a psdp.Attribute
+	if i > 0 {
+		a = psdp.NewAttribute(value[:i], value[i+1:])
+	} else {
+		a = psdp.NewPropertyAttribute(value)
+	}
+
+	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
+	latestMediaDesc.Attributes = append(latestMediaDesc.Attributes, a)
+	return nil
+}
+
+// Unmarshal decodes a SessionDescription.
+// This is rewritten from scratch to guarantee compatibility with most RTSP
+// implementations.
+func (s *SessionDescription) Unmarshal(byts []byte) error {
+	str := string(byts)
+
+	type stateVal int
+
+	const (
+		stateInitial stateVal = iota
+		stateSession
+		stateMedia
+	)
+
+	state := stateInitial
+
+	for _, line := range strings.Split(strings.ReplaceAll(str, "\r", ""), "\n") {
+		if line == "" {
+			continue
+		}
+
+		if len(line) < 2 || line[1] != '=' {
+			return fmt.Errorf("invalid line: (%s)", line)
+		}
+
+		key := line[0]
+		val := line[2:]
+
+		switch state {
+		case stateInitial:
+			switch key {
+			case 'v':
+				err := s.unmarshalVersion(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+				state = stateSession
+
+			default:
+				return fmt.Errorf("invalid key: %c (%s)", key, line)
+			}
+
+		case stateSession:
+			switch key {
+			case 'o':
+				err := s.unmarshalOrigin(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 's':
+				err := s.unmarshalSessionName(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'i':
+				err := s.unmarshalSessionInformation(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'u':
+				err := s.unmarshalURI(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'e':
+				err := s.unmarshalEmail(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'p':
+				err := s.unmarshalPhone(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'c':
+				err := s.unmarshalSessionConnectionInformation(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'b':
+				err := s.unmarshalSessionBandwidth(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'z':
+				err := s.unmarshalTimeZones(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'k':
+				err := s.unmarshalSessionEncryptionKey(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'a':
+				err := s.unmarshalSessionAttribute(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 't':
+				err := s.unmarshalTiming(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'r':
+				err := s.unmarshalRepeatTimes(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'm':
+				err := s.unmarshalMediaDescription(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+				state = stateMedia
+
+			default:
+				return fmt.Errorf("invalid key: %c (%s)", key, line)
+			}
+
+		case stateMedia:
+			switch key {
+			case 'm':
+				err := s.unmarshalMediaDescription(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'i':
+				err := s.unmarshalMediaTitle(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'c':
+				err := s.unmarshalMediaConnectionInformation(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'b':
+				err := s.unmarshalMediaBandwidth(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'k':
+				err := s.unmarshalMediaEncryptionKey(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			case 'a':
+				err := s.unmarshalMediaAttribute(val)
+				if err != nil {
+					return fmt.Errorf("%s (%s)", err, line)
+				}
+
+			default:
+				return fmt.Errorf("invalid key: %c (%s)", key, line)
+			}
+		}
+	}
+
+	return nil
+}

sdp/unmarshal.go

@@ -1,628 +0,0 @@
-package sdp
-
-import (
-	"errors"
-	"fmt"
-	"net/url"
-	"strconv"
-	"strings"
-
-	psdp "github.com/pion/sdp/v3"
-)
-
-type stateVal int
-
-const (
-	stateInitial stateVal = iota
-	stateSession
-	stateMedia
-)
-
-var (
-	errSDPInvalidSyntax       = errors.New("sdp: invalid syntax")
-	errSDPInvalidNumericValue = errors.New("sdp: invalid numeric value")
-	errSDPInvalidValue        = errors.New("sdp: invalid value")
-	errSDPInvalidPortValue    = errors.New("sdp: invalid port value")
-)
-
-func indexOf(element string, data []string) int {
-	for k, v := range data {
-		if element == v {
-			return k
-		}
-	}
-	return -1
-}
-
-func parsePort(value string) (int, error) {
-	port, err := strconv.Atoi(value)
-	if err != nil {
-		return 0, fmt.Errorf("%w `%v`", errSDPInvalidPortValue, port)
-	}
-
-	if port < 0 || port > 65536 {
-		return 0, fmt.Errorf("%w -- out of range `%v`", errSDPInvalidPortValue, port)
-	}
-
-	return port, nil
-}
-
-func (s *SessionDescription) unmarshalVersion(value string) error {
-	if value != "0" {
-		return fmt.Errorf("invalid version")
-	}
-	return nil
-}
-
-func (s *SessionDescription) unmarshalSessionName(value string) error {
-	s.SessionName = psdp.SessionName(value)
-	return nil
-}
-
-func (s *SessionDescription) unmarshalOrigin(value string) error {
-	// special case for live reporter app
-	if value[:3] == "-0 " {
-		value = "- 0 " + value[3:]
-	}
-
-	// special case for sone onvif2 cameras
-	if value[len(value)-1] == ' ' {
-		value += "127.0.0.1"
-	}
-
-	fields := strings.Fields(value)
-	if len(fields) != 6 {
-		return fmt.Errorf("%w `o=%v`", errSDPInvalidSyntax, fields)
-	}
-
-	sessionID, err := strconv.ParseUint(fields[1], 10, 64)
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[1])
-	}
-
-	sessionVersion, err := strconv.ParseUint(fields[2], 10, 64)
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[2])
-	}
-
-	// Set according to currently registered with IANA
-	// https://tools.ietf.org/html/rfc4566#section-8.2.6
-	if i := indexOf(fields[3], []string{"IN"}); i == -1 {
-		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[3])
-	}
-
-	// Set according to currently registered with IANA
-	// https://tools.ietf.org/html/rfc4566#section-8.2.7
-	if i := indexOf(fields[4], []string{"IP4", "IP6"}); i == -1 {
-		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[3])
-	}
-
-	s.Origin = psdp.Origin{
-		Username:       fields[0],
-		SessionID:      sessionID,
-		SessionVersion: sessionVersion,
-		NetworkType:    fields[3],
-		AddressType:    fields[4],
-		UnicastAddress: fields[5],
-	}
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalSessionInformation(value string) error {
-	sessionInformation := psdp.Information(value)
-	s.SessionInformation = &sessionInformation
-	return nil
-}
-
-func (s *SessionDescription) unmarshalURI(value string) error {
-	var err error
-	s.URI, err = url.Parse(value)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalEmail(value string) error {
-	emailAddress := psdp.EmailAddress(value)
-	s.EmailAddress = &emailAddress
-	return nil
-}
-
-func (s *SessionDescription) unmarshalPhone(value string) error {
-	phoneNumber := psdp.PhoneNumber(value)
-	s.PhoneNumber = &phoneNumber
-	return nil
-}
-
-func unmarshalConnectionInformation(value string) (*psdp.ConnectionInformation, error) {
-	fields := strings.Fields(value)
-	if len(fields) < 2 {
-		return nil, fmt.Errorf("%w `c=%v`", errSDPInvalidSyntax, fields)
-	}
-
-	// Set according to currently registered with IANA
-	// https://tools.ietf.org/html/rfc4566#section-8.2.6
-	if i := indexOf(fields[0], []string{"IN"}); i == -1 {
-		return nil, fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[0])
-	}
-
-	// Set according to currently registered with IANA
-	// https://tools.ietf.org/html/rfc4566#section-8.2.7
-	if i := indexOf(fields[1], []string{"IP4", "IP6"}); i == -1 {
-		return nil, fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[1])
-	}
-
-	connAddr := new(psdp.Address)
-	if len(fields) > 2 {
-		connAddr.Address = fields[2]
-	}
-
-	return &psdp.ConnectionInformation{
-		NetworkType: fields[0],
-		AddressType: fields[1],
-		Address:     connAddr,
-	}, nil
-}
-
-func (s *SessionDescription) unmarshalSessionConnectionInformation(value string) error {
-	var err error
-	s.ConnectionInformation, err = unmarshalConnectionInformation(value)
-	if err != nil {
-		return fmt.Errorf("%w `c=%v`", errSDPInvalidSyntax, value)
-	}
-	return nil
-}
-
-func unmarshalBandwidth(value string) (*psdp.Bandwidth, error) {
-	parts := strings.Split(value, ":")
-	if len(parts) != 2 {
-		return nil, fmt.Errorf("%w `b=%v`", errSDPInvalidValue, parts)
-	}
-
-	experimental := strings.HasPrefix(parts[0], "X-")
-	if experimental {
-		parts[0] = strings.TrimPrefix(parts[0], "X-")
-	} else if i := indexOf(parts[0], []string{"CT", "AS", "RR"}); i == -1 {
-		// Set according to currently registered with IANA
-		// https://tools.ietf.org/html/rfc4566#section-5.8
-		return nil, fmt.Errorf("%w `%v`", errSDPInvalidValue, parts[0])
-	}
-
-	bandwidth, err := strconv.ParseUint(parts[1], 10, 64)
-	if err != nil {
-		return nil, fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, parts[1])
-	}
-
-	return &psdp.Bandwidth{
-		Experimental: experimental,
-		Type:         parts[0],
-		Bandwidth:    bandwidth,
-	}, nil
-}
-
-func (s *SessionDescription) unmarshalSessionBandwidth(value string) error {
-	bandwidth, err := unmarshalBandwidth(value)
-	if err != nil {
-		return fmt.Errorf("%w `b=%v`", errSDPInvalidValue, value)
-	}
-	s.Bandwidth = append(s.Bandwidth, *bandwidth)
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalTimeZones(value string) error {
-	// These fields are transimitted in pairs
-	// z=<adjustment time> <offset> <adjustment time> <offset> ....
-	// so we are making sure that there are actually multiple of 2 total.
-	fields := strings.Fields(value)
-	if len(fields)%2 != 0 {
-		return fmt.Errorf("%w `t=%v`", errSDPInvalidSyntax, fields)
-	}
-
-	for i := 0; i < len(fields); i += 2 {
-		var timeZone psdp.TimeZone
-
-		var err error
-		timeZone.AdjustmentTime, err = strconv.ParseUint(fields[i], 10, 64)
-		if err != nil {
-			return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
-		}
-
-		timeZone.Offset, err = parseTimeUnits(fields[i+1])
-		if err != nil {
-			return err
-		}
-
-		s.TimeZones = append(s.TimeZones, timeZone)
-	}
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalSessionEncryptionKey(value string) error {
-	encryptionKey := psdp.EncryptionKey(value)
-	s.EncryptionKey = &encryptionKey
-	return nil
-}
-
-func (s *SessionDescription) unmarshalSessionAttribute(value string) error {
-	i := strings.IndexRune(value, ':')
-	var a psdp.Attribute
-	if i > 0 {
-		a = psdp.NewAttribute(value[:i], value[i+1:])
-	} else {
-		a = psdp.NewPropertyAttribute(value)
-	}
-
-	s.Attributes = append(s.Attributes, a)
-	return nil
-}
-
-func (s *SessionDescription) unmarshalTiming(value string) error {
-	fields := strings.Fields(value)
-	if len(fields) < 2 {
-		return fmt.Errorf("%w `t=%v`", errSDPInvalidSyntax, fields)
-	}
-
-	td := psdp.TimeDescription{}
-
-	var err error
-	td.Timing.StartTime, err = strconv.ParseUint(fields[0], 10, 64)
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[1])
-	}
-
-	td.Timing.StopTime, err = strconv.ParseUint(fields[1], 10, 64)
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[1])
-	}
-
-	s.TimeDescriptions = append(s.TimeDescriptions, td)
-
-	return nil
-}
-
-func parseTimeUnits(value string) (int64, error) {
-	// Some time offsets in the protocol can be provided with a shorthand
-	// notation. This code ensures to convert it to NTP timestamp format.
-	//      d - days (86400 seconds)
-	//      h - hours (3600 seconds)
-	//      m - minutes (60 seconds)
-	//      s - seconds (allowed for completeness)
-	switch value[len(value)-1:] {
-	case "d":
-		num, err := strconv.ParseInt(value[:len(value)-1], 10, 64)
-		if err != nil {
-			return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
-		}
-		return num * 86400, nil
-	case "h":
-		num, err := strconv.ParseInt(value[:len(value)-1], 10, 64)
-		if err != nil {
-			return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
-		}
-		return num * 3600, nil
-	case "m":
-		num, err := strconv.ParseInt(value[:len(value)-1], 10, 64)
-		if err != nil {
-			return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
-		}
-		return num * 60, nil
-	}
-
-	num, err := strconv.ParseInt(value, 10, 64)
-	if err != nil {
-		return 0, fmt.Errorf("%w `%v`", errSDPInvalidValue, value)
-	}
-
-	return num, nil
-}
-
-func (s *SessionDescription) unmarshalRepeatTimes(value string) error {
-	fields := strings.Fields(value)
-	if len(fields) < 3 {
-		return fmt.Errorf("%w `r=%v`", errSDPInvalidSyntax, fields)
-	}
-
-	latestTimeDesc := &s.TimeDescriptions[len(s.TimeDescriptions)-1]
-
-	newRepeatTime := psdp.RepeatTime{}
-	var err error
-	newRepeatTime.Interval, err = parseTimeUnits(fields[0])
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
-	}
-
-	newRepeatTime.Duration, err = parseTimeUnits(fields[1])
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
-	}
-
-	for i := 2; i < len(fields); i++ {
-		offset, err := parseTimeUnits(fields[i])
-		if err != nil {
-			return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields)
-		}
-		newRepeatTime.Offsets = append(newRepeatTime.Offsets, offset)
-	}
-	latestTimeDesc.RepeatTimes = append(latestTimeDesc.RepeatTimes, newRepeatTime)
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalMediaDescription(value string) error {
-	fields := strings.Fields(value)
-	if len(fields) < 4 {
-		return fmt.Errorf("%w `m=%v`", errSDPInvalidSyntax, fields)
-	}
-
-	newMediaDesc := &psdp.MediaDescription{}
-
-	// <media>
-	// Set according to currently registered with IANA
-	// https://tools.ietf.org/html/rfc4566#section-5.14
-	if i := indexOf(fields[0], []string{"audio", "video", "text", "application", "message"}); i == -1 {
-		return fmt.Errorf("%w `%v`", errSDPInvalidValue, fields[0])
-	}
-	newMediaDesc.MediaName.Media = fields[0]
-
-	// <port>
-	parts := strings.Split(fields[1], "/")
-	var err error
-	newMediaDesc.MediaName.Port.Value, err = parsePort(parts[0])
-	if err != nil {
-		return fmt.Errorf("%w `%v`", errSDPInvalidPortValue, parts[0])
-	}
-
-	if len(parts) > 1 {
-		portRange, err := strconv.Atoi(parts[1])
-		if err != nil {
-			return fmt.Errorf("%w `%v`", errSDPInvalidValue, parts)
-		}
-		newMediaDesc.MediaName.Port.Range = &portRange
-	}
-
-	// <proto>
-	// Set according to currently registered with IANA
-	// https://tools.ietf.org/html/rfc4566#section-5.14
-	for _, proto := range strings.Split(fields[2], "/") {
-		if i := indexOf(proto, []string{"UDP", "RTP", "AVP", "SAVP", "SAVPF",
-			"MP2T", "TLS", "DTLS", "SCTP", "AVPF", "TCP"}); i == -1 {
-			return fmt.Errorf("%w `%v`", errSDPInvalidNumericValue, fields[2])
-		}
-		newMediaDesc.MediaName.Protos = append(newMediaDesc.MediaName.Protos, proto)
-	}
-
-	// <fmt>...
-	for i := 3; i < len(fields); i++ {
-		newMediaDesc.MediaName.Formats = append(newMediaDesc.MediaName.Formats, fields[i])
-	}
-
-	s.MediaDescriptions = append(s.MediaDescriptions, newMediaDesc)
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalMediaTitle(value string) error {
-	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
-	mediaTitle := psdp.Information(value)
-	latestMediaDesc.MediaTitle = &mediaTitle
-	return nil
-}
-
-func (s *SessionDescription) unmarshalMediaConnectionInformation(value string) error {
-	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
-	var err error
-	latestMediaDesc.ConnectionInformation, err = unmarshalConnectionInformation(value)
-	if err != nil {
-		return fmt.Errorf("%w `c=%v`", errSDPInvalidSyntax, value)
-	}
-
-	return nil
-}
-
-func (s *SessionDescription) unmarshalMediaBandwidth(value string) error {
-	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
-	bandwidth, err := unmarshalBandwidth(value)
-	if err != nil {
-		return fmt.Errorf("%w `b=%v`", errSDPInvalidSyntax, value)
-	}
-	latestMediaDesc.Bandwidth = append(latestMediaDesc.Bandwidth, *bandwidth)
-	return nil
-}
-
-func (s *SessionDescription) unmarshalMediaEncryptionKey(value string) error {
-	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
-	encryptionKey := psdp.EncryptionKey(value)
-	latestMediaDesc.EncryptionKey = &encryptionKey
-	return nil
-}
-
-func (s *SessionDescription) unmarshalMediaAttribute(value string) error {
-	i := strings.IndexRune(value, ':')
-	var a psdp.Attribute
-	if i > 0 {
-		a = psdp.NewAttribute(value[:i], value[i+1:])
-	} else {
-		a = psdp.NewPropertyAttribute(value)
-	}
-
-	latestMediaDesc := s.MediaDescriptions[len(s.MediaDescriptions)-1]
-	latestMediaDesc.Attributes = append(latestMediaDesc.Attributes, a)
-	return nil
-}
-
-// Unmarshal decodes a SessionDescription.
-// This is rewritten from scratch to guarantee compatibility with most RTSP
-// implementations.
-func (s *SessionDescription) Unmarshal(byts []byte) error {
-	str := string(byts)
-
-	state := stateInitial
-
-	for _, line := range strings.Split(strings.ReplaceAll(str, "\r", ""), "\n") {
-		if line == "" {
-			continue
-		}
-
-		if len(line) < 2 || line[1] != '=' {
-			return fmt.Errorf("invalid line: (%s)", line)
-		}
-
-		key := line[0]
-		val := line[2:]
-
-		switch state {
-		case stateInitial:
-			switch key {
-			case 'v':
-				err := s.unmarshalVersion(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-				state = stateSession
-
-			default:
-				return fmt.Errorf("invalid key: %c (%s)", key, line)
-			}
-
-		case stateSession:
-			switch key {
-			case 'o':
-				err := s.unmarshalOrigin(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 's':
-				err := s.unmarshalSessionName(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'i':
-				err := s.unmarshalSessionInformation(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'u':
-				err := s.unmarshalURI(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'e':
-				err := s.unmarshalEmail(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'p':
-				err := s.unmarshalPhone(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'c':
-				err := s.unmarshalSessionConnectionInformation(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'b':
-				err := s.unmarshalSessionBandwidth(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'z':
-				err := s.unmarshalTimeZones(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'k':
-				err := s.unmarshalSessionEncryptionKey(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'a':
-				err := s.unmarshalSessionAttribute(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 't':
-				err := s.unmarshalTiming(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'r':
-				err := s.unmarshalRepeatTimes(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'm':
-				err := s.unmarshalMediaDescription(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-				state = stateMedia
-
-			default:
-				return fmt.Errorf("invalid key: %c (%s)", key, line)
-			}
-
-		case stateMedia:
-			switch key {
-			case 'm':
-				err := s.unmarshalMediaDescription(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'i':
-				err := s.unmarshalMediaTitle(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'c':
-				err := s.unmarshalMediaConnectionInformation(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'b':
-				err := s.unmarshalMediaBandwidth(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'k':
-				err := s.unmarshalMediaEncryptionKey(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			case 'a':
-				err := s.unmarshalMediaAttribute(val)
-				if err != nil {
-					return fmt.Errorf("%s (%s)", err, line)
-				}
-
-			default:
-				return fmt.Errorf("invalid key: %c (%s)", key, line)
-			}
-		}
-	}
-
-	return nil
-}