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use crate::rtp::SSRC;
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("packet truncated")]
Truncated,
#[error("unsupported version")]
Version,
}
pub struct RtcpPacket<'a> {
parts: Vec<RtcpPart<'a>>,
}
pub enum RtcpPart<'a> {
SenderReport(SenderReport<'a>),
ReceiverReport(ReceiverReport),
SourceDescription(SourceDescription),
Bye(Bye),
Application(Application<'a>),
}
struct SenderReport<'a> {
ssrc: SSRC,
sender_info: SenderInfo,
reports: Vec<ReportBlock>,
extension: &'a [u8],
}
struct ReceiverReport {
sender_ssrc: SSRC,
reports: Vec<ReportBlock>,
}
struct SourceDescription {}
struct Bye {}
struct Application<'a> {
data: &'a [u8],
}
struct SenderInfo {
ntp_ts: u64,
rtp_ts: u32,
packet_count: u32,
octet_count: u32,
}
struct ReportBlock {
ssrc: SSRC,
fraction_lost: u8,
cumulative_packets_lost: u32,
ext_max_seq_num_recv: u32,
interarrical_jitter: u32,
lsr: u32,
dlsr: u32,
}
impl<'a> RtcpPacket<'a> {
pub fn parse(mut packet: &'a [u8]) -> Result<RtcpPacket<'a>, Error> {
let mut parts = Vec::with_capacity(2);
while packet.len() > 0 {
if packet.len() < 4 {
return Err(Error::Truncated);
}
let version = (packet[0] & 0b11000000) >> 6;
if !matches!(version, 1 | 2) {
return Err(Error::Version);
}
let padding = (packet[0] & 0b00100000) != 0;
let num_reports = (packet[0] & 0b00011111) >> 0;
let packet_type = packet[1];
let length = u16::from_be_bytes([packet[2], packet[3]]);
match packet_type {
200 => {
// Sender Report
if packet.len() < 28 + 24 * num_reports as usize {
return Err(Error::Truncated);
}
let ssrc = SSRC(u32::from_be_bytes(packet[4..8].try_into().unwrap()));
let sender_info = SenderInfo::parse(packet[8..28].try_into().unwrap());
let mut reports = Vec::with_capacity(num_reports as usize);
for n in 0..num_reports as usize {
reports.push(ReportBlock::parse(
packet[28 + 24 * n..28 + 24 * (n + 1)].try_into().unwrap(),
));
}
let extension = &packet[28 + 24 * num_reports as usize..];
parts.push(RtcpPart::SenderReport(SenderReport {
reports,
sender_info,
ssrc,
extension,
}))
}
201 => { // Receiver Report
}
_ => {}
}
packet = &packet[length as usize..];
}
Ok(Self { parts })
}
pub fn write(&self, out: &mut Vec<u8>) {
for part in &self.parts {
let version = 2;
let padding = false;
match part {
RtcpPart::SenderReport(sender_report) => {
out.push(
version << 6 | (padding as u8) << 5 | sender_report.reports.len() as u8,
);
out.push(200);
}
RtcpPart::ReceiverReport(receiver_report) => todo!(),
RtcpPart::SourceDescription(source_description) => todo!(),
RtcpPart::Bye(bye) => todo!(),
RtcpPart::Application(application) => todo!(),
}
}
}
}
impl SenderInfo {
pub const SIZE: usize = 5 * 4;
pub fn parse(packet: [u8; 5 * 4]) -> SenderInfo {
Self {
ntp_ts: u64::from_be_bytes(packet[0..8].try_into().unwrap()),
rtp_ts: u32::from_be_bytes(packet[8..12].try_into().unwrap()),
packet_count: u32::from_be_bytes(packet[12..16].try_into().unwrap()),
octet_count: u32::from_be_bytes(packet[16..20].try_into().unwrap()),
}
}
pub fn write(&self, out: &mut Vec<u8>) {
out.extend(self.ntp_ts.to_be_bytes());
out.extend(self.rtp_ts.to_be_bytes());
out.extend(self.packet_count.to_be_bytes());
out.extend(self.octet_count.to_be_bytes());
}
}
impl ReportBlock {
pub fn parse(packet: [u8; 6 * 4]) -> ReportBlock {
Self {
ssrc: SSRC(u32::from_be_bytes(packet[0..4].try_into().unwrap())),
fraction_lost: packet[4],
cumulative_packets_lost: u32::from_be_bytes([0, packet[5], packet[6], packet[7]]),
ext_max_seq_num_recv: u32::from_be_bytes(packet[8..12].try_into().unwrap()),
interarrical_jitter: u32::from_be_bytes(packet[12..16].try_into().unwrap()),
lsr: u32::from_be_bytes(packet[16..20].try_into().unwrap()),
dlsr: u32::from_be_bytes(packet[20..24].try_into().unwrap()),
}
}
pub fn write(&self, out: &mut Vec<u8>) {
out.extend(self.ssrc.0.to_be_bytes());
out.push(self.fraction_lost);
out.extend(&self.cumulative_packets_lost.to_be_bytes()[1..]);
out.extend(self.ext_max_seq_num_recv.to_be_bytes());
out.extend(self.interarrical_jitter.to_be_bytes());
out.extend(self.lsr.to_be_bytes());
out.extend(self.dlsr.to_be_bytes());
}
}
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