std.socket and raw socket for Layer 2 capture.

Jun 05, 2023

zann

Jun 05, 2023

Adam D Ruppe

Jun 06, 2023

zann

June 05, 2023

std.socket and raw socket for Layer 2 capture.

Posted by zann

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zann

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Hello together

I've a question about layer-2 (ethernet frames) capturing.
I have a Network and Linux Admin background, but not a really heavy programmer.

In C i can create a socket( AF_PACKET, SOCK_RAW, 0 ) and thats it.

import core.stdc ... # there is no socket.d ...

# i used a:
$ grep -ir socket /usr/include/dlang/dmd/core/stdc/"
# but no success.

Ok so it's have to be possible with D there is all i need i think and at this moment i'm struggle on:

import std.stdio;
import std.socket;


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);

}

But for the moment i think it's really impossible to capture ethernet frames with D.
Or can someone explain where my "error in head" is?

Capture ip packets or tcp / udp segments, thats all easy and i already did, but it is not what i need.
I need the whole Ethernet Frame.

Best regards

Erich Zann

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.

On Monday, 5 June 2023 at 21:03:12 UTC, Adam D Ruppe wrote: > 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. Hehey, thanks a lot, that helps much. Yes checking the return value is important, but first i want that the socket can be created. And thats not the case. If i can create the socket that i need, at this point, the clean coding with error checking starts.

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