turn_rs/processor/
channel_data.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
use super::{Context, Response};
use crate::StunClass;
use faster_stun::ChannelData;

/// process channel data
///
/// If the ChannelData message is received on a channel that is not bound
/// to any peer, then the message is silently discarded.
///
/// On the client, it is RECOMMENDED that the client discard the
/// ChannelData message if the client believes there is no active
/// permission towards the peer.  On the server, the receipt of a
/// ChannelData message MUST NOT refresh either the channel binding or
/// the permission towards the peer.
///
/// On the server, if no errors are detected, the server relays the
/// application data to the peer by forming a UDP datagram as follows:
///
/// * the source transport address is the relayed transport address of
/// the allocation, where the allocation is determined by the 5-tuple
/// on which the ChannelData message arrived;
///
/// * the destination transport address is the transport address to
/// which the channel is bound;
///
/// * the data following the UDP header is the contents of the data
/// field of the ChannelData message.
///
/// The resulting UDP datagram is then sent to the peer.  Note that if
/// the Length field in the ChannelData message is 0, then there will be
/// no data in the UDP datagram, but the UDP datagram is still formed and
/// sent [(Section 4.1 of [RFC6263])](https://tools.ietf.org/html/rfc6263#section-4.1).
pub fn process(ctx: Context, data: ChannelData<'_>) -> Option<Response<'_>> {
    let addr = ctx.env.router.get_channel_bound(&ctx.addr, data.number)?;
    let interface = ctx.env.router.get_interface(&addr)?;
    let to = (&ctx.env.interface != &interface.addr).then(|| interface.addr);
    Some(Response::new(data.buf, StunClass::Channel, Some(addr), to))
}