snap.shadowsocks-rust.sslocal-daemon.service crashes periodically with tun interface client

[AlexCG22]

When using tun interface, sslocal-daemon crashes periodically (once in 1-2 days in my setup).

This behavior is observed both on physical hardware and in virtualized environments.

Jul 21 16:01:29 shadowsocks-rust.sslocal-daemon[116325]: thread 'smoltcp-poll' panicked at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/smoltcp-0.12.0/src/wire/tcp.rs:81:13:
Jul 21 16:01:29 shadowsocks-rust.sslocal-daemon[116325]: attempt to subtract sequence numbers with underflow
Jul 21 16:01:29 shadowsocks-rust.sslocal-daemon[116325]: note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Jul 21 16:01:29 systemd[1]: snap.shadowsocks-rust.sslocal-daemon.service: Main process exited, code=killed, status=6/ABRT
Jul 21 16:01:29 systemd[1]: snap.shadowsocks-rust.sslocal-daemon.service: Failed with result 'signal'.

Platform: Debian stable.

config.json:

{
    "locals": [
        {
            "local_address":"127.0.0.1",
            "local_port":3000
        },
        {
            "protocol":"tun",
            "tun_interface_name":"tun1",
            "outbound_bind_interface":"lo"
        }
    ],
    "servers": [
        {
            "server":"xxx.xx.xxx.xxx",
            "server_port":443,
            "method":"aes-256-gcm",
            "password":"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
        }
    ],
   "mode":"tcp_and_udp",
   "timeout": 300
}

[zonyitoo]

This is a known issue in smoltcp: smoltcp-rs/smoltcp#1048 .

Are you running the latest version?

[AlexCG22]

$ snap list shadowsocks-rust 
Name              Version               Rev   Tracking       Publisher  Notes
shadowsocks-rust  v1.23.5.r0.g8f9419ef  2291  latest/stable  ducksoft   -

[zonyitoo]

Actually it is quite hard to reproduce. Do you have a stable case?

[AlexCG22]

Unfortunately, no. It seems to happen randomly, and I can't pinpoint it to specific conditions, like periods of high load or something like that.

I used to run the same configuration on physical hardware. Now it works on a VPS. It seems to crash more frequently on the VPS, within 1-2 days, while on the physical server it happens about once a week.

[zonyitoo]

The tun interface process packets locally, so it shouldn't have anything to do with your remote servers.

[AlexCG22]

To be clear, I route packets between tun interfaces, one of which belongs to sslocal, the other to OpenVPN server.
It works great, except for this issue.