std.socket and raw socket for Layer 2 capture.

[Adam D Ruppe]

On Monday, 5 June 2023 at 18:13:48 UTC, zann wrote:
> In C i can create a socket( AF_PACKET, SOCK_RAW, 0 ) and thats 
> it.
>
> ```d
> import core.stdc ... # there is no socket.d ...

That's cuz socket isn't stdc, it is posix.

// in C it is #include <sys/socket.h>
// and it is "CONFORMING TO Posix..."
// so that means in D you can generally find it under
// core.sys.posix for the posix conformation, then
// sys.socket cuz of sys/socket. thus this:

import core.sys.posix.sys.socket;

Lets you use the same functions as from C.

> $ grep -ir socket /usr/include/dlang/dmd/core/stdc/"

expand the search to core, not just stdc as a general rule.

> Socket init_sock() {
>   auto socket = new Socket( AddressFamily.INET, SocketType.RAW, 
> ProtocolType.RAW );
>   socket.setOption( SocketOptionLevel.RAW, SocketOption.TYPE, 3 
> );
>   return socket;
> }
>
> void main() {
>
>   ubyte[1500] socket_buffer;
>
>   writeln("init socket.");
>   auto sock = init_sock();
>
>   sock.receiveFrom( socket_buffer );
>   writeln(socket_buffer);
>
> }

I've never actually used a raw socket but you might also have to 
pass an address buffer to receiveFrom and you definitely should 
be checking the return value minimally.