Identify program that connects to a Unix Domain Socket

Question

I have a program that is listening to a Unix Domain Socket.

When a client connects to the socket I\'d like to find out which program connected and then decide if I allow

Answer 1

I searched for this quite a bit, so I will show you this example on how to use SO_PEERCRED on a socket sock to get the pid/uid/gid of the peer of a socket:

int len;
struct ucred ucred;

len = sizeof(struct ucred);

if (getsockopt(sock, SOL_SOCKET, SO_PEERCRED, &ucred, &len) == -1) {
    //getsockopt failed
}

printf("Credentials from SO_PEERCRED: pid=%ld, euid=%ld, egid=%ld\n",
    (long) ucred.pid, (long) ucred.uid, (long) ucred.gid);