moq-rs/moq-transport/src/message/subscribe.rs

127 lines
3.3 KiB
Rust

use crate::coding::{Decode, DecodeError, Encode, EncodeError, Params, VarInt};
use crate::coding::{AsyncRead, AsyncWrite};
/// Sent by the subscriber to request all future objects for the given track.
///
/// Objects will use the provided ID instead of the full track name, to save bytes.
#[derive(Clone, Debug)]
pub struct Subscribe {
/// An ID we choose so we can map to the track_name.
// Proposal: https://github.com/moq-wg/moq-transport/issues/209
pub id: VarInt,
/// The track namespace.
pub namespace: String,
/// The track name.
pub name: String,
/// The start/end group/object.
pub start_group: SubscribeLocation,
pub start_object: SubscribeLocation,
pub end_group: SubscribeLocation,
pub end_object: SubscribeLocation,
/// Optional parameters
pub params: Params,
}
impl Subscribe {
pub async fn decode<R: AsyncRead>(r: &mut R) -> Result<Self, DecodeError> {
let id = VarInt::decode(r).await?;
let namespace = String::decode(r).await?;
let name = String::decode(r).await?;
let start_group = SubscribeLocation::decode(r).await?;
let start_object = SubscribeLocation::decode(r).await?;
let end_group = SubscribeLocation::decode(r).await?;
let end_object = SubscribeLocation::decode(r).await?;
// You can't have a start object without a start group.
if start_group == SubscribeLocation::None && start_object != SubscribeLocation::None {
return Err(DecodeError::InvalidSubscribeLocation);
}
// You can't have an end object without an end group.
if end_group == SubscribeLocation::None && end_object != SubscribeLocation::None {
return Err(DecodeError::InvalidSubscribeLocation);
}
// NOTE: There's some more location restrictions in the draft, but they're enforced at a higher level.
let params = Params::decode(r).await?;
Ok(Self {
id,
namespace,
name,
start_group,
start_object,
end_group,
end_object,
params,
})
}
pub async fn encode<W: AsyncWrite>(&self, w: &mut W) -> Result<(), EncodeError> {
self.id.encode(w).await?;
self.namespace.encode(w).await?;
self.name.encode(w).await?;
self.start_group.encode(w).await?;
self.start_object.encode(w).await?;
self.end_group.encode(w).await?;
self.end_object.encode(w).await?;
self.params.encode(w).await?;
Ok(())
}
}
/// Signal where the subscription should begin, relative to the current cache.
#[derive(Clone, Debug, PartialEq)]
pub enum SubscribeLocation {
None,
Absolute(VarInt),
Latest(VarInt),
Future(VarInt),
}
impl SubscribeLocation {
pub async fn decode<R: AsyncRead>(r: &mut R) -> Result<Self, DecodeError> {
let kind = VarInt::decode(r).await?;
match kind.into_inner() {
0 => Ok(Self::None),
1 => Ok(Self::Absolute(VarInt::decode(r).await?)),
2 => Ok(Self::Latest(VarInt::decode(r).await?)),
3 => Ok(Self::Future(VarInt::decode(r).await?)),
_ => Err(DecodeError::InvalidSubscribeLocation),
}
}
pub async fn encode<W: AsyncWrite>(&self, w: &mut W) -> Result<(), EncodeError> {
match self {
Self::None => {
VarInt::from_u32(0).encode(w).await?;
}
Self::Absolute(val) => {
VarInt::from_u32(1).encode(w).await?;
val.encode(w).await?;
}
Self::Latest(val) => {
VarInt::from_u32(2).encode(w).await?;
val.encode(w).await?;
}
Self::Future(val) => {
VarInt::from_u32(3).encode(w).await?;
val.encode(w).await?;
}
}
Ok(())
}
}