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use std::ops::Deref;
use crate::io::Id;
use crate::rtp::{ChannelId, Direction, Extensions, Mid, Ssrc};
use crate::sctp::{DcepOpen, ReliabilityType};
use crate::sdp::{MediaLine, Msid, Offer};
use crate::media::{CodecConfig, MLine, MediaKind, PayloadParams};
use crate::session::MLineOrApp;
use crate::Rtc;
pub(crate) struct Changes(pub Vec<Change>);
#[derive(Debug)]
pub(crate) enum Change {
AddMedia(AddMedia),
AddApp(Mid),
AddChannel(ChannelId, DcepOpen),
Direction(Mid, Direction),
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct AddMedia {
pub mid: Mid,
pub cname: String,
pub msid: Msid,
pub kind: MediaKind,
pub dir: Direction,
pub ssrcs: Vec<(Ssrc, Option<Ssrc>)>,
pub params: Vec<PayloadParams>,
pub index: usize,
}
pub struct ChangeSet<'a> {
rtc: &'a mut Rtc,
changes: Changes,
}
impl<'a> ChangeSet<'a> {
pub(crate) fn new(rtc: &'a mut Rtc) -> Self {
ChangeSet {
rtc,
changes: Changes(vec![]),
}
}
pub fn has_changes(&self) -> bool {
!self.changes.is_empty()
}
pub fn add_media(&mut self, kind: MediaKind, dir: Direction, cname: Option<String>) -> Mid {
let mid = self.rtc.new_mid();
let cname = if let Some(cname) = cname {
fn is_token_char(c: &char) -> bool {
let u = *c as u32;
u == 0x21
|| (0x23..=0x27).contains(&u)
|| (0x2a..=0x2b).contains(&u)
|| (0x2d..=0x2e).contains(&u)
|| (0x30..=0x39).contains(&u)
|| (0x41..=0x5a).contains(&u)
|| (0x5e..0x7e).contains(&u)
}
cname.chars().filter(is_token_char).take(64).collect()
} else {
Id::<20>::random().to_string()
};
let ssrcs = {
let has_rtx = kind == MediaKind::Video;
let ssrc_base = if has_rtx { 2 } else { 1 };
let simulcast_count = 1;
let ssrc_count = ssrc_base * simulcast_count;
let mut v = Vec::with_capacity(ssrc_count);
let mut prev = 0.into();
for i in 0..ssrc_count {
let new_ssrc = self.rtc.new_ssrc();
let is_rtx = has_rtx && i % 2 == 1;
let repairs = if is_rtx { Some(prev) } else { None };
v.push((new_ssrc, repairs));
prev = new_ssrc;
}
v
};
let msid = Msid {
stream_id: cname.clone(),
track_id: Id::<30>::random().to_string(),
};
let add = AddMedia {
mid,
cname,
msid,
kind,
dir,
ssrcs,
params: vec![],
index: 0,
};
self.changes.0.push(Change::AddMedia(add));
mid
}
pub fn set_direction(&mut self, mid: Mid, dir: Direction) {
let Some(media) = self.rtc.session.m_line_by_mid_mut(mid) else {
return;
};
if media.direction() == dir {
return;
}
self.changes.0.push(Change::Direction(mid, dir));
}
pub fn add_channel(&mut self, label: String) -> ChannelId {
let has_m_line = self.rtc.session.app().is_some();
if !has_m_line {
let mid = self.rtc.new_mid();
self.changes.0.push(Change::AddApp(mid));
}
let id = self.rtc.new_sctp_channel();
let dcep = DcepOpen {
unordered: false,
channel_type: ReliabilityType::Reliable,
reliability_parameter: 0,
label,
priority: 0,
protocol: String::new(),
};
self.changes.0.push(Change::AddChannel(id, dcep));
id
}
pub fn apply(self) -> Option<Offer> {
let requires_negotiation = self.changes.iter().any(|c| c.requires_negotiation());
if requires_negotiation {
Some(self.rtc.set_pending(self.changes))
} else {
self.rtc.apply_direct_changes(self.changes);
None
}
}
}
impl Changes {
pub fn take_new_channels(&mut self) -> Vec<(ChannelId, DcepOpen)> {
let mut v = vec![];
if self.0.is_empty() {
return v;
}
for i in (0..self.0.len()).rev() {
if matches!(&self.0[i], Change::AddChannel(_, _)) {
if let Change::AddChannel(id, dcep) = self.0.remove(i) {
v.push((id, dcep));
}
}
}
v
}
pub fn ensure_correct_answer(&self, lines: &[&MediaLine]) -> Option<String> {
if self.count_new_m_lines() != lines.len() {
return Some(format!(
"Differing m-line count in offer vs answer: {} != {}",
self.count_new_m_lines(),
lines.len()
));
}
'next: for l in lines {
let mid = l.mid();
for m in &self.0 {
use Change::*;
match m {
AddMedia(v) if v.mid == mid => {
if !l.typ.is_media() {
return Some(format!(
"Answer m-line for mid ({}) is not of media type: {:?}",
mid, l.typ
));
}
continue 'next;
}
AddApp(v) if *v == mid => {
if !l.typ.is_channel() {
return Some(format!(
"Answer m-line for mid ({}) is not a data channel: {:?}",
mid, l.typ
));
}
continue 'next;
}
_ => {}
}
}
return Some(format!("Mid in answer is not in offer: {mid}"));
}
None
}
fn count_new_m_lines(&self) -> usize {
self.0
.iter()
.filter(|c| matches!(c, Change::AddMedia(_) | Change::AddApp(_)))
.count()
}
pub fn as_new_m_lines<'a, 'b: 'a>(
&'a self,
index_start: usize,
config: &'b CodecConfig,
exts: &'b Extensions,
) -> impl Iterator<Item = MLineOrApp> + '_ {
self.0
.iter()
.enumerate()
.filter_map(move |(idx, c)| c.as_new_m_line(index_start + idx, config, exts))
}
pub(crate) fn apply_to(&self, lines: &mut [MediaLine]) {
for change in &self.0 {
if let Change::Direction(mid, dir) = change {
if let Some(line) = lines.iter_mut().find(|l| l.mid() == *mid) {
if let Some(dir_pos) = line.attrs.iter().position(|a| a.is_direction()) {
line.attrs[dir_pos] = (*dir).into();
}
}
}
}
}
}
impl Change {
fn as_new_m_line(
&self,
index: usize,
config: &CodecConfig,
exts: &Extensions,
) -> Option<MLineOrApp> {
use Change::*;
match self {
AddMedia(v) => {
let mut add = v.clone();
add.params = config.all_for_kind(v.kind).copied().collect();
add.index = index;
let m_line = MLine::from_add_media(add, *exts);
Some(MLineOrApp::MLine(m_line))
}
AddApp(mid) => {
let channel = (*mid, index).into();
Some(MLineOrApp::App(channel))
}
_ => None,
}
}
fn requires_negotiation(&self) -> bool {
match self {
Change::AddMedia(_) => true,
Change::AddApp(_) => true,
Change::AddChannel(_, _) => false,
Change::Direction(_, _) => true,
}
}
}
impl Deref for Changes {
type Target = [Change];
fn deref(&self) -> &Self::Target {
&self.0
}
}