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server/vendor/github.com/pion/rtcp/compound_packet.go

@@ -0,0 +1,161 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package rtcp
+
+import (
+	"fmt"
+	"strings"
+)
+
+// A CompoundPacket is a collection of RTCP packets transmitted as a single packet with
+// the underlying protocol (for example UDP).
+//
+// To maximize the resolution of receiption statistics, the first Packet in a CompoundPacket
+// must always be either a SenderReport or a ReceiverReport.  This is true even if no data
+// has been sent or received, in which case an empty ReceiverReport must be sent, and even
+// if the only other RTCP packet in the compound packet is a Goodbye.
+//
+// Next, a SourceDescription containing a CNAME item must be included in each CompoundPacket
+// to identify the source and to begin associating media for purposes such as lip-sync.
+//
+// Other RTCP packet types may follow in any order. Packet types may appear more than once.
+type CompoundPacket []Packet
+
+// Validate returns an error if this is not an RFC-compliant CompoundPacket.
+func (c CompoundPacket) Validate() error {
+	if len(c) == 0 {
+		return errEmptyCompound
+	}
+
+	// SenderReport and ReceiverReport are the only types that
+	// are allowed to be the first packet in a compound datagram
+	switch c[0].(type) {
+	case *SenderReport, *ReceiverReport:
+		// ok
+	default:
+		return errBadFirstPacket
+	}
+
+	for _, pkt := range c[1:] {
+		switch p := pkt.(type) {
+		// If the number of RecetpionReports exceeds 31 additional ReceiverReports
+		// can be included here.
+		case *ReceiverReport:
+			continue
+
+		// A SourceDescription containing a CNAME must be included in every
+		// CompoundPacket.
+		case *SourceDescription:
+			var hasCNAME bool
+			for _, c := range p.Chunks {
+				for _, it := range c.Items {
+					if it.Type == SDESCNAME {
+						hasCNAME = true
+					}
+				}
+			}
+
+			if !hasCNAME {
+				return errMissingCNAME
+			}
+
+			return nil
+
+		// Other packets are not permitted before the CNAME
+		default:
+			return errPacketBeforeCNAME
+		}
+	}
+
+	// CNAME never reached
+	return errMissingCNAME
+}
+
+// CNAME returns the CNAME that *must* be present in every CompoundPacket
+func (c CompoundPacket) CNAME() (string, error) {
+	var err error
+
+	if len(c) < 1 {
+		return "", errEmptyCompound
+	}
+
+	for _, pkt := range c[1:] {
+		sdes, ok := pkt.(*SourceDescription)
+		if ok {
+			for _, c := range sdes.Chunks {
+				for _, it := range c.Items {
+					if it.Type == SDESCNAME {
+						return it.Text, err
+					}
+				}
+			}
+		} else {
+			_, ok := pkt.(*ReceiverReport)
+			if !ok {
+				err = errPacketBeforeCNAME
+			}
+		}
+	}
+	return "", errMissingCNAME
+}
+
+// Marshal encodes the CompoundPacket as binary.
+func (c CompoundPacket) Marshal() ([]byte, error) {
+	if err := c.Validate(); err != nil {
+		return nil, err
+	}
+
+	p := []Packet(c)
+	return Marshal(p)
+}
+
+// MarshalSize returns the size of the packet once marshaled
+func (c CompoundPacket) MarshalSize() int {
+	l := 0
+	for _, p := range c {
+		l += p.MarshalSize()
+	}
+	return l
+}
+
+// Unmarshal decodes a CompoundPacket from binary.
+func (c *CompoundPacket) Unmarshal(rawData []byte) error {
+	out := make(CompoundPacket, 0)
+	for len(rawData) != 0 {
+		p, processed, err := unmarshal(rawData)
+		if err != nil {
+			return err
+		}
+
+		out = append(out, p)
+		rawData = rawData[processed:]
+	}
+	*c = out
+
+	return c.Validate()
+}
+
+// DestinationSSRC returns the synchronization sources associated with this
+// CompoundPacket's reception report.
+func (c CompoundPacket) DestinationSSRC() []uint32 {
+	if len(c) == 0 {
+		return nil
+	}
+
+	return c[0].DestinationSSRC()
+}
+
+func (c CompoundPacket) String() string {
+	out := "CompoundPacket\n"
+	for _, p := range c {
+		stringer, canString := p.(fmt.Stringer)
+		if canString {
+			out += stringer.String()
+		} else {
+			out += stringify(p)
+		}
+	}
+	out = strings.TrimSuffix(strings.ReplaceAll(out, "\n", "\n\t"), "\t")
+	return out
+}