Getting IP address from an interface in C
 

My program (in C) sends data via 4 interfaces. ppp0,ppp1,ppp2,ppp3. I have to find a way to get the IP address of each of the sending interfaces and I have to log these IP addresses. The program reads data from a file and sends it to the server. It has to also send the IP address to the server. What function can I use? and where do I put it? Any help would be appreciated.



int i;
for (i = 0; i < 4; i++){

if (setsockopt(client_socket, SOL_SOCKET, SO_BINDTODEVICE, ifname[i], strlen(ifname[i]) + 1) ==-1) {
printf ("Error setting interface %s \n", ifname[i]);
perror("XXX ");
} else{
printf("about to connect ip addr %s\n", ServerIPAddr);
if (connect(client_socket, (struct sockaddr *)&server_ssin, sizeof(struct sockaddr_in)) == -1 ) {
printf ("Error connecting to server from interface %s \n", ifname[i]);
} else {
printf("Connected to server on port %d from interface %s \n", dport, ifname[i]);
break;
}
}
}


int data_read=0;
while ((data_read = read(file_tosend, buffer, BUFF_SIZE)) > 0){
if ((data = send(client_socket, buffer, data_read, 0)) == -1) {
printf("Error sending data to server\n");
return -1;
}
total_sent += data;
memset(buffer, 0x0, BUFF_SIZE);
}

IT IS URGENTLY NEEDED
Thank you in advance

and if u look around more on my main page u'll see a guide to netlink, which can also do this for u, although a bit more complex.