`SockProtocol` lacks protocols; No way to use ETH_P_ALL

[mexus]

Currently the only protocols supported in SockProtocol are Tcp and Udp (for linux), while there are many more.

For example, I'm working with raw sockets and I need to specify a special ETH_P_ALL protocol (man 7 packet), and there is one important thing about it: its number has to be presented in network byte order when passed to the system socket call.

Currently the SockProtocol enum simply provides i32 constants, so I can't put htons conversion there since there is no const fn call for that.

There is also no way to provide an arbitrary integer as a protocol number to the nix's socket call, hence I'm left with no options.

So I would say it would be great to have an option to pass the protocol number as a number (i32 or whatever) to the socket call, but it might be there are other ways to address the issue.

[kristate]

I am also interested in ETH_P_ALL

[Susurrus]

Why don't we just account for the network byte order translation within the nix wrapper rather than make the user do it? And if you provided an example of how you'd like to use the API, I'm sure we could hash something out that wouldn't be hard to implement. Unfortunately we don't have the manpower to implement requested features like this and rely on contributors to do that heavy lifting.

[kristate]

Update: Working on PR

[jaykru]

What's the status of this issue? There was a PR that seems to solve most of the problems #865 but it hasn't been touched in years.

[asomers]

That PR has been abandoned. You may resurrect it if you like.

[ajguerrer]

For anyone who encountered this issue, as a workaround I had some luck by making a socket and calling bind on a sockaddr_ll with the sll_protocol field set to the protocol you like:

let fd = socket(AddressFamily::Packet, ty, SockFlag::SOCK_NONBLOCK, None)?;
let addr = LinkAddr(libc::sockaddr_ll {
    sll_family: libc::AF_PACKET as libc::c_ushort,
    // Equivalent to htons(libc::ETH_P_ALL). 
    // Make sure the integer width is 16 bits first! Still getting my sanity back from that one lololol.
    sll_protocol: (libc::ETH_P_ALL as libc::c_ushort).to_be(),
    sll_ifindex: 0 /* match any interface */,
    sll_hatype: 1,
    sll_pkttype: 0,
    sll_halen: 6,
    sll_addr: [0; 8],
});
bind(fd, &SockAddr::Link(addr))?;

[devanlai]

As of #1684, LinkAddr is opaque and it seems to be necessary to use the unsafe LinkAddr::from_raw() to handle this situation, which feels like a major step backward to me:

let fd = socket(AddressFamily::Packet, ty, SockFlag::SOCK_NONBLOCK, None)?;
let sockaddr = libc::sockaddr_ll {
    sll_family: libc::AF_PACKET as libc::c_ushort,
    // Equivalent to htons(libc::ETH_P_ALL). 
    sll_protocol: (libc::ETH_P_ALL as libc::c_ushort).to_be(),
    sll_ifindex: 0 /* match any interface */,
    sll_hatype: 1,
    sll_pkttype: 0,
    sll_halen: 6,
    sll_addr: [0; 8],
};
let p_sockaddr = &raw const sockaddr as *const libc::sockaddr;
let len = Some(std::mem::size_of::<libc::sockaddr_ll>() as libc::socklen_t);
let link_addr = unsafe { LinkAddr::from_raw(p_sockaddr, len).unwrap() };
bind(fd, &link_addr)?;