/* * CSSE 132 * Rose-Hulman Institute of Technology * Computer Science and Software Engineering * * whoconnected.c - basic socket server that prints information about incoming * connections, greets clients, then disconnects them. * * Author: Sid Stamm */ #include #include #include #include #include #include int main(int argc, char** argv) { // The first step is to create a server socket. int srv_sock; // server socket (used for listening for clients) // Next, construct local address structure struct sockaddr_in serv_addr; // for local address serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); // accept on any interface serv_addr.sin_port = htons(20000); // Create a socket for listening. srv_sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if (srv_sock < 1) { printf("Failed to create server socket\n"); return; } // lets us reuse the port immediately after we kill the server int optval = 1; setsockopt(srv_sock, SOL_SOCKET, SO_REUSEADDR, (const void *)&optval, sizeof(int)); // Bind to address and port int result = 0; result = bind(srv_sock, (struct sockaddr*) &serv_addr, sizeof(struct sockaddr_in)); if (result < 0) { printf("Failed to bind to port.\n"); return; } // Listen for incoming connections result = listen(srv_sock, 5); if (result < 0) { printf("Failed to listen.\n"); return; } // some variables reused for each client. int cli_sock; struct hostent* hostname; unsigned int sock_addr_len; struct sockaddr_in client_addr; // for remote address // Handle incoming clients forever while(1) { // WARNING: must initialize this length to an appropriate size or accept() // won't fill the address struct with information about the client. sock_addr_len = sizeof(struct sockaddr_in); // Accept one client (into cli_sock) and put client's address into client_addr. cli_sock = accept(srv_sock, (struct sockaddr*)&client_addr, &sock_addr_len); printf("Connected to client socket %d\n", cli_sock); printf(" len: %d\n", sock_addr_len); printf(" addr: %s\n", inet_ntoa(client_addr.sin_addr)); // It's also fun to print out the remote host's name. hostname = gethostbyaddr(&(client_addr.sin_addr), sizeof(client_addr.sin_addr), AF_INET); printf(" name: %s\n", hostname->h_name); // HANDLE ONE CLIENT send(cli_sock, "Sup, dude?\n", 11, 0); // Shutdown and close (this gracefully disconnects the client) shutdown(cli_sock, SHUT_RDWR); close(cli_sock); } // outside the loop, the server has nothing left to do. Close the server socket. close(srv_sock); return 0; }
