CreatePermission is called for every TURN packet sent

[Andrepuel]

From the source code

async fn send_to(&mut self, p: &[u8], addr: SocketAddr) -> Result<usize> {
    // ...
    let mut perm = if let Some(perm) = self.perm_map.find(&addr) {
        *perm
    } else {
        let perm = Permission::default();
        self.perm_map.insert(&addr, perm);
        perm
    };

    let mut result = Ok(());
    for _ in 0..MAX_RETRY_ATTEMPTS {
        result = self.create_perm(&mut perm, addr).await;
        if let Err(err) = &result {
            if !Error::ErrTryAgain.equal(err) {
                break;
            }
        }
    }

The perm variable is read from perm_map but never written back to it. So, every time send_to is called, it will get a Idle permission, which triggers a new CreatePermission on the create_perm function.

After the create_perm is called, the perm variable should be set back to perm_map.

Besides that, there is no Lifetime tracking. If we didn't receive any packet from a given address for more than 300 seconds, then the Permission for that given address should be removed from the perm_map. Because we must update the permission.

[rainliu]

Yes, it is a bug in https://sourcegraph.com/github.com/webrtc-rs/turn/-/blob/src/client/relay_conn.rs?L212-218.

Will fix it soon.

[Andrepuel]

Besides that, there is no Lifetime tracking. If we didn't receive any packet from a given address for more than 300 seconds, then the Permission for that given address should be removed from the perm_map. Because we must update the permission.

Could you confirm this? Upon closer inspection I've found a reference to a timed refresh of permissions:

https://sourcegraph.com/github.com/webrtc-rs/turn@909eac74d669d62202cd89783ef7e6136e1f4026/-/blob/src/client/relay_conn.rs?L600

Does that mean we don't need to track permissions timeout?

[rainliu]

The bug of CreatePermission is called for every TURN packet sent should be fixed in commit # f593cc4d1940a9cbae03ff32d70b33d2f8bda969.

[Andrepuel]

The bug of CreatePermission is called for every TURN packet sent should be fixed in commit # f593cc4d1940a9cbae03ff32d70b33d2f8bda969.

I can confirm that this commit fixes the problem.