Question

According to this article from msdn (
http://msdn.microsoft.com/en-us/library/windows/desktop/ms740496(v=vs.85).aspx) the struct varies depending on which protocol is selected!

Now I want to use this code from http://www.intelliproject.net/articles/showArticle/index/check_tcp_udp_port to check if a port is open or not!

Now I have the struct sockaddr as follows:

struct sockaddr {
    ushort  sa_family;
    char    sa_data[14];
};

but need this strcuture:

struct sockaddr {
    short   sin_family;
    u_short sin_port;
    struct  in_addr sin_addr;
    char    sin_zero[8];
};

Which changes are necessary?

(Ws2_32.lib is linked and following includes

#define WIN32_LEAN_AND_MEAN

// sockets
#include "windows.h"
#include <winsock2.h>
#include <ws2tcpip.h>

Thx

Answer 1

In sockets API the address structure to use depends on the protocol. If you are using IPv4, the structure you need is sockaddr_in.

The sockets API appeared long ago when void * wasn’t in standard. Pointers to sockaddr are used all over the sockets functions in exactly the same way as we would use void * pointers. The functions expect you to pass the pointers to the structures related to protocols you use. The unpleasant thing is that you need a cast whenever you pass a pointer to your address structure, but there is nothing you can do about it.

IPv4 example:

struct sockaddr_in address;

// ...

memset( &address, 0, sizeof(address) );

address.sin_family = AF_INET;
address.sin_port = htons(1100);
address.sin_addr.s_addr = INADDR_ANY;

if ( bind( sock, (struct sockaddr *)&address, sizeof(address) ) < 0 )
{
   //....
}