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digitalmars.D - std.socket and raw socket for Layer 2 capture.

reply zann <zann arklab.dev> writes:
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.

```d



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

```

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:

```d
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
Jun 05 2023
parent reply Adam D Ruppe <destructionator gmail.com> writes:
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



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.
Jun 05 2023
parent zann <zann arklab.dev> writes:
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



 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.
Jun 05 2023