Beej's Guide to Network Programming Using Internet Sockets

Beej’s Guide to Network Programming Using Internet Sockets 448.3. connect()Connect a socket to a serverPrototypes#include #include int connect(int sockfd, const struct sockaddr *serv_addr,socklen_t addrlen);DescriptionOnce you’ve built a socket descriptor with the socket() call, you can connect() that socketto a remote server using the well-named connect() system call. All you need to do is pass it thesocket descriptor and the address of the server you’re interested in getting to know better. (Oh, andthe length of the address, which is commonly passed to functions like this.)If you haven’t yet called bind() on the socket descriptor, it is automatically bound to yourIP address and a random local port. This is usually just fine with you, since you really don’t carewhat your local port is; you only care what the remote port is so you can put it in the serv_addrparameter. You can call bind() if you really want your client socket to be on a specific IP addressand port, but this is pretty rare.Once the socket is connect()ed, you’re free to send() and recv() data on it to your heart’scontent.Special note: if you connect() a SOCK_DGRAM UDP socket to a remote host, you can usesend() and recv() as well as sendto() and recvfrom(). If you want.Return ValueReturns zero on success, or -1 on error (and errno will be set accordingly.)Exampleint s;struct sockaddr_in serv_addr;// pretend the server is at 63.161.169.137 listening on port 80:myaddr.sin_family = AF_INET;myaddr.sin_port = htons(80);inet_aton("63.161.169.137", &myaddr.sin_addr.s_addr);s = socket(PF_INET, SOCK_STREAM, 0);connect(s, (struct sockaddr*)myaddr, sizeof(myaddr));// now we’re ready to send() and recv()See Alsosocket(), bind()