Re: ICMP socket with Gambas - working

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Le 29/06/2025 à 17:17, Lee a écrit :
> On 6/29/25 9:59 AM, vuott@xxxxxxxxxxxx wrote:
> > Hello Lee,
> > ...and now ?
>
> Wow, great minds think alike, eh?
>
> I haven't tried your code yet, but I see it does something very similar 
> to what I did to finally get my code working.
>
> I abandoned the use of structures because, for whatever reason, 
> extraneous bytes were being added in. The two Short members of Struct 
> Sockaddr (sin_family and sin_port) took 4 bytes total and then there 
> were 4 extra bytes in the structure which put sin_addr at offset 8 when 
> it should have been at offset 4. Likewise, the single Integer member of 
> Struct In_addr comprised 8 bytes when it should have been only 4. 
> Perhaps that is due to structure field alignment, but that doesn't make 
> sense to me as two Shorts align well with one Integer.

It's because you used "Long" for SinAddr, whereas it must be "Integer". 
"Long" in Gambas is a 64-bit integer.

Every structure field is aligned to a memory address that is a multiple 
of the field size, but as the fields order is kept, some extra padding 
may be added between misaligned fields.

Moreover, the structure you must declare is actually "SockAddr_In", not 
"SockAddr". So:

Public Struct SockAddr_In
  SinFamily As Short
  SinPort As Short
  SinAddr As Integer
  _Padding[8] As Byte
End Struct

Because you have SockAddr_In6 too for IPV6, which is different, but both 
can be aliased to SockAddr which is declared that way:

Public Struct SockAddr_In
  SinFamily As Short
  _Padding[14] As Byte
End Struct

Regards,

--
Benoît Minisini.