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// Copyright (C) 2021 Scott Lamb <slamb@slamb.org>
// SPDX-License-Identifier: MIT OR Apache-2.0
//! High-level RTSP library.
//!
//! Currently this is useful for clients; it will be extended to support
//! servers and proxies.
#![forbid(clippy::print_stderr, clippy::print_stdout)]
// I prefer to use from_str_radix(..., 10) to explicitly note the base.
#![allow(clippy::from_str_radix_10)]
use bytes::Bytes;
use log::trace;
use rand::Rng;
use rtsp_types::Message;
use std::fmt::{Debug, Display};
use std::net::{IpAddr, SocketAddr, UdpSocket};
use std::num::NonZeroU32;
use std::ops::Range;
mod error;
mod hex;
pub mod rtcp;
pub mod rtp;
#[cfg(test)]
mod testutil;
pub use error::Error;
/// Wraps the supplied `ErrorInt` and returns it as an `Err`.
macro_rules! bail {
($e:expr) => {
return Err(crate::error::Error(std::sync::Arc::new($e)))
};
}
macro_rules! wrap {
($e:expr) => {
crate::error::Error(std::sync::Arc::new($e))
};
}
pub mod client;
pub mod codec;
//mod error;
mod tokio;
use error::ErrorInt;
/// A received RTSP message.
#[derive(Debug)]
struct ReceivedMessage {
ctx: RtspMessageContext,
msg: Message<Bytes>,
}
/// An annotated RTP timestamp.
///
/// This couples together three pieces of information:
///
/// * The stream's starting time. In client use, this is often as received in the RTSP
/// `RTP-Info` header but may be controlled via [`crate::client::InitialTimestampPolicy`].
/// According to [RFC 3550 section 5.1](https://datatracker.ietf.org/doc/html/rfc3550#section-5.1), "the initial
/// value of the timestamp SHOULD be random".
///
/// * The codec-specific clock rate.
///
/// * The timestamp as an `i64`. In client use, its top bits should be inferred from wraparounds
/// of 32-bit RTP timestamps. The Retina client's policy is that timestamps that differ by more
/// than `i32::MAX` from previous timestamps are treated as backwards jumps. It's allowed for
/// a timestamp to indicate a time *before* the stream's starting point.
///
/// In combination, these allow conversion to "normal play time" (NPT): seconds since start of
/// the stream.
///
/// According to [RFC 3550 section 5.1](https://datatracker.ietf.org/doc/html/rfc3550#section-5.1),
/// RTP timestamps "MUST be derived from a clock that increments monotonically". In practice,
/// many RTP servers violate this. The Retina client allows such violations unless
/// [`crate::client::PlayOptions::enforce_timestamps_with_max_jump_secs`] says otherwise.
///
/// [`Timestamp`] can't represent timestamps which overflow/underflow `i64` can't be constructed or
/// elapsed times (`elapsed = timestamp - start`) which underflow `i64`. The client will return
/// error in these cases. This should rarely cause problems. It'd take ~2^32 packets (~4 billion)
/// to advance the time this far forward or backward even with a hostile server.
///
/// The [`Display`] and [`Debug`] implementations currently display:
/// * the bottom 32 bits, as seen in RTP packet headers. This advances at a
/// codec-specified clock rate.
/// * the full timestamp.
/// * NPT
#[derive(Copy, Clone, PartialEq, Eq)]
pub struct Timestamp {
/// A timestamp which must be compared to `start`.
timestamp: i64,
/// The codec-specified clock rate, in Hz. Must be non-zero.
clock_rate: NonZeroU32,
/// The stream's starting time, as specified in the RTSP `RTP-Info` header.
start: u32,
}
impl Timestamp {
/// Creates a new timestamp unless `timestamp - start` underflows.
#[inline]
pub fn new(timestamp: i64, clock_rate: NonZeroU32, start: u32) -> Option<Self> {
timestamp.checked_sub(i64::from(start)).map(|_| Timestamp {
timestamp,
clock_rate,
start,
})
}
/// Returns time since some arbitrary point before the stream started.
#[inline]
pub fn timestamp(&self) -> i64 {
self.timestamp
}
/// Returns timestamp of the start of the stream.
#[inline]
pub fn start(&self) -> u32 {
self.start
}
/// Returns codec-specified clock rate, in Hz.
#[inline]
pub fn clock_rate(&self) -> NonZeroU32 {
self.clock_rate
}
/// Returns elapsed time since the stream start in clock rate units.
#[inline]
pub fn elapsed(&self) -> i64 {
self.timestamp - i64::from(self.start)
}
/// Returns elapsed time since the stream start in seconds, aka "normal play
/// time" (NPT).
#[inline]
pub fn elapsed_secs(&self) -> f64 {
(self.elapsed() as f64) / (self.clock_rate.get() as f64)
}
/// Returns `self + delta` unless it would overflow.
pub fn try_add(&self, delta: u32) -> Option<Self> {
// Check for `timestamp` overflow only. We don't need to check for
// `timestamp - start` underflow because delta is non-negative.
self.timestamp
.checked_add(i64::from(delta))
.map(|timestamp| Timestamp {
timestamp,
clock_rate: self.clock_rate,
start: self.start,
})
}
}
impl Display for Timestamp {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(
f,
"{} (mod-2^32: {}), npt {:.03}",
self.timestamp,
self.timestamp as u32,
self.elapsed_secs()
)
}
}
impl Debug for Timestamp {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
Display::fmt(self, f)
}
}
/// The Unix epoch as an [`NtpTimestamp`].
pub const UNIX_EPOCH: NtpTimestamp = NtpTimestamp((2_208_988_800) << 32);
/// A wallclock time represented using the format of the Network Time Protocol.
///
/// NTP timestamps are in a fixed-point representation of seconds since
/// 0h UTC on 1 January 1900. The top 32 bits represent the integer part
/// (wrapping around every 68 years) and the bottom 32 bits represent the
/// fractional part.
///
/// This is a simple wrapper around a `u64` in that format, with a `Display`
/// impl that writes the timestamp as a human-readable string. Currently this
/// assumes the time is within 68 years of 1970; the string will be incorrect
/// after `2038-01-19T03:14:07Z`.
///
/// An `NtpTimestamp` isn't necessarily gathered from a real NTP server.
/// Reported NTP timestamps are allowed to jump backwards and/or be complete
/// nonsense.
///
/// The NTP timestamp of the Unix epoch is available via the constant [`UNIX_EPOCH`].
#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)]
pub struct NtpTimestamp(pub u64);
impl std::fmt::Display for NtpTimestamp {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let since_epoch = self.0.wrapping_sub(UNIX_EPOCH.0);
let sec_since_epoch = (since_epoch >> 32) as u32;
let tm = time::at(time::Timespec {
sec: i64::from(sec_since_epoch),
nsec: 0,
});
let ms = ((since_epoch & 0xFFFF_FFFF) * 1_000) >> 32;
let zone_minutes = tm.tm_utcoff.abs() / 60;
write!(
f,
"{}.{:03}{}{:02}:{:02}",
tm.strftime("%FT%T").map_err(|_| std::fmt::Error)?,
ms,
if tm.tm_utcoff > 0 { '+' } else { '-' },
zone_minutes / 60,
zone_minutes % 60
)
}
}
impl std::fmt::Debug for NtpTimestamp {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
// Write both the raw and display forms.
write!(f, "{} /* {} */", self.0, self)
}
}
/// A wall time taken from the local machine's realtime clock, used in error reporting.
///
/// Currently this just allows formatting via `Debug` and `Display`.
#[derive(Copy, Clone, Debug)]
pub struct WallTime(time::Timespec);
impl WallTime {
fn now() -> Self {
Self(time::get_time())
}
}
impl Display for WallTime {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
std::fmt::Display::fmt(
&time::at(self.0)
.strftime("%FT%T")
.map_err(|_| std::fmt::Error)?,
f,
)
}
}
/// RTSP connection context.
///
/// This gives enough information to pick out the flow in a packet capture.
#[derive(Copy, Clone, Debug)]
pub struct ConnectionContext {
local_addr: std::net::SocketAddr,
peer_addr: std::net::SocketAddr,
established_wall: WallTime,
}
impl ConnectionContext {
#[doc(hidden)]
pub fn dummy() -> Self {
let addr = SocketAddr::new(IpAddr::V4(std::net::Ipv4Addr::UNSPECIFIED), 0);
Self {
local_addr: addr,
peer_addr: addr,
established_wall: WallTime::now(),
}
}
}
impl Display for ConnectionContext {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
// TODO: this current hardcodes the assumption we are the client.
// Change if/when adding server code.
write!(
f,
"{}(me)->{}@{}",
&self.local_addr, &self.peer_addr, &self.established_wall,
)
}
}
/// Context of a received message (or read error) within an RTSP connection.
///
/// When paired with a [`ConnectionContext`], this should allow picking the
/// message out of a packet capture.
#[derive(Copy, Clone, Debug)]
pub struct RtspMessageContext {
/// The starting byte position within the input stream. The bottom 32 bits
/// can be compared to the relative TCP sequence number.
pos: u64,
/// Time when the application parsed the message. Caveat: this may not
/// closely match the time on a packet capture if the application is
/// overloaded (or if `CLOCK_REALTIME` jumps).
received_wall: WallTime,
received: std::time::Instant,
}
impl RtspMessageContext {
#[doc(hidden)]
pub fn dummy() -> Self {
Self {
pos: 0,
received_wall: WallTime::now(),
received: std::time::Instant::now(),
}
}
pub fn received(&self) -> std::time::Instant {
self.received
}
pub fn pos(&self) -> u64 {
self.pos
}
}
impl Display for RtspMessageContext {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}@{}", self.pos, &self.received_wall)
}
}
/// Context for an active stream (RTP+RTCP session), either TCP or UDP. Owned version.
#[derive(Copy, Clone, Debug)]
pub struct StreamContext(StreamContextInner);
impl StreamContext {
#[doc(hidden)]
pub fn dummy() -> Self {
StreamContext(StreamContextInner::Dummy)
}
}
impl Display for StreamContext {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match &self.0 {
StreamContextInner::Tcp(tcp) => {
write!(
f,
"TCP, interleaved channel ids {}-{}",
tcp.rtp_channel_id,
tcp.rtp_channel_id + 1
)
}
StreamContextInner::Udp(udp) => Display::fmt(udp, f),
StreamContextInner::Dummy => write!(f, "dummy"),
}
}
}
#[derive(Copy, Clone, Debug)]
enum StreamContextInner {
Tcp(TcpStreamContext),
Udp(UdpStreamContext),
Dummy,
}
/// Context for a UDP stream (aka UDP-based RTP transport). Unstable/internal. Exposed for benchmarks.
///
/// This stores only the RTP addresses; the RTCP addresses are assumed to use
/// the same IP and one port higher.
#[doc(hidden)]
#[derive(Copy, Clone, Debug)]
pub struct UdpStreamContext {
local_ip: IpAddr,
peer_ip: IpAddr,
local_rtp_port: u16,
peer_rtp_port: u16,
}
/// Context for a TCP stream. Unstable/internal. Exposed for benchmarks.
///
/// This stores only the RTP channel id; the RTCP channel id is assumed to be one higher.
#[doc(hidden)]
#[derive(Copy, Clone, Debug)]
pub struct TcpStreamContext {
rtp_channel_id: u8,
}
impl Display for UdpStreamContext {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
// TODO: this assumes we are the client. Revisit when adding server support.
write!(
f,
"{}:{}-{}(me) -> {}:{}-{}",
self.local_ip,
self.local_rtp_port,
self.local_rtp_port + 1,
self.peer_ip,
self.peer_rtp_port,
self.peer_rtp_port + 1
)
}
}
/// Context for an RTP or RTCP packet, received either via RTSP interleaved data or UDP.
///
/// Should be paired with an [`ConnectionContext`] of the RTSP connection that started
/// the session. In the interleaved data case, it's assumed the packet was received over
/// that same connection.
#[derive(Copy, Clone, Debug)]
pub struct PacketContext(PacketContextInner);
impl PacketContext {
#[doc(hidden)]
pub fn dummy() -> PacketContext {
Self(PacketContextInner::Dummy)
}
}
#[derive(Copy, Clone, Debug)]
enum PacketContextInner {
Tcp { msg_ctx: RtspMessageContext },
Udp { received_wall: WallTime },
Dummy,
}
impl Display for PacketContext {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self.0 {
PacketContextInner::Udp { received_wall } => std::fmt::Display::fmt(&received_wall, f),
PacketContextInner::Tcp { msg_ctx } => std::fmt::Display::fmt(&msg_ctx, f),
PacketContextInner::Dummy => write!(f, "dummy"),
}
}
}
/// Returns the range within `buf` that represents `subset`.
/// If `subset` is empty, returns None; otherwise panics if `subset` is not within `buf`.
pub(crate) fn as_range(buf: &[u8], subset: &[u8]) -> Option<std::ops::Range<usize>> {
if subset.is_empty() {
return None;
}
let subset_p = subset.as_ptr() as usize;
let buf_p = buf.as_ptr() as usize;
let off = match subset_p.checked_sub(buf_p) {
Some(off) => off,
None => panic!(
"{}-byte subset not within {}-byte buf",
subset.len(),
buf.len()
),
};
let end = off + subset.len();
assert!(end <= buf.len());
Some(off..end)
}
/// A pair of local UDP sockets used for RTP and RTCP transmission.
///
/// The RTP port is always even, and the RTCP port is always the following (odd) integer.
struct UdpPair {
rtp_port: u16,
rtp_socket: UdpSocket,
rtcp_socket: UdpSocket,
}
impl UdpPair {
fn for_ip(ip_addr: IpAddr) -> Result<Self, std::io::Error> {
const MAX_TRIES: usize = 10;
const ALLOWED_RTP_RANGE: Range<u16> = 5000..65000; // stolen from ffmpeg's defaults.
let mut rng = rand::thread_rng();
for i in 0..MAX_TRIES {
let rtp_port = rng.gen_range(ALLOWED_RTP_RANGE) & !0b1;
debug_assert!(ALLOWED_RTP_RANGE.contains(&rtp_port));
let rtp_addr = SocketAddr::new(ip_addr, rtp_port);
let rtp_socket = match UdpSocket::bind(rtp_addr) {
Ok(s) => s,
Err(e) if e.kind() == std::io::ErrorKind::AddrInUse => {
trace!(
"Try {}/{}: unable to bind RTP addr {:?}",
i,
MAX_TRIES,
rtp_addr
);
continue;
}
Err(e) => return Err(e),
};
let rtcp_addr = SocketAddr::new(ip_addr, rtp_port + 1);
let rtcp_socket = match UdpSocket::bind(rtcp_addr) {
Ok(s) => s,
Err(e) if e.kind() == std::io::ErrorKind::AddrInUse => {
trace!(
"Try {}/{}: unable to bind RTCP addr {:?}",
i,
MAX_TRIES,
rtcp_addr
);
continue;
}
Err(e) => return Err(e),
};
return Ok(Self {
rtp_port,
rtp_socket,
rtcp_socket,
});
}
Err(std::io::Error::new(
std::io::ErrorKind::AddrInUse,
format!(
"Unable to find even/odd pair in {}:{}..{} after {} tries",
ip_addr, ALLOWED_RTP_RANGE.start, ALLOWED_RTP_RANGE.end, MAX_TRIES
),
))
}
}
#[cfg(test)]
mod test {
use std::net::Ipv4Addr;
use super::*;
#[test]
fn local_udp_pair() {
// Just test that it succeeds.
UdpPair::for_ip(IpAddr::V4(Ipv4Addr::LOCALHOST)).unwrap();
}
}