songgao/water

Latest changes broken darwin TUNs

jpillora opened this issue · 3 comments

jpillora commented

Can you please provide a working macOS example, which:

  • creates tun interface
  • assigns ip (10.0.0.1)
  • responds to icmp (ping 10.0.0.1 works)

This program https://github.com/twitchyliquid64/subnet works because it vendors an older version, if you update github.com/songgao/water in vendor/ you'll see that it no longer works on macOS.

jpillora commented

Ah seems like the TUN interface emits/requires a leading 0x00000002. Do you know why this is?

songgao commented

It sounds like related to #21

By default the kernel prepends a 4-byte header to packets read from the TUN fd, and expects that header from packets written into the fd. To avoid that, water uses IFF_NO_PI on Linux so that user don't have to worry about that header. But the same flag isn't supported on darwin. So that PR added a wrapper to "fake" IFF_NO_PI behavior on darwin, so that it's consistent with Linux.

That repo doesn't have a SHA1 of vendored commit, but from this file it seems it has the latest water code regarding to IFF_NO_PI. What commit did you try to vendor into it? Any chance you vendored an old commit?

songgao commented

Closing due to inactivity. Please let me know if you are still having issues.