Hi all,
I have a simple client/server setup running on my localhost that is currently set to be in a loop and to send a tcp packet containing "This is the message to send" to the server.
I'd like to have the client send the message once, wait (kind of like a keep alive) and send it again. I am noticing that it sends a bunch of packets at once and the server doesn't necessarily know what to do with it. The server echoing that the client has been sending traffic is a bit wacky.
Any ideas to get me going?
Client.c
server.cCode:#include <stdio.h> #include <netdb.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <errno.h> #include <stdlib.h> #include <strings.h> #include <arpa/inet.h> #include <unistd.h> #define SERVER_TCP_PORT 7000 // Default port #define BUFLEN 1024 // Buffer length int main (int argc, char **argv) { int n, bytes_to_read; int sd, port; struct hostent *hp; struct sockaddr_in server; char *host, *bp, rbuf[BUFLEN], **pptr; char *sbuf="This is a message to send\n\r"; char str[16]; switch(argc) { case 2: host = argv[1]; // Host name port = SERVER_TCP_PORT; break; case 3: host = argv[1]; port = atoi(argv[2]); // User specified port break; default: fprintf(stderr, "Usage: %s host [port]\n", argv[0]); exit(1); } // Create the socket if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("Cannot create socket"); exit(1); } bzero((char *)&server, sizeof(struct sockaddr_in)); server.sin_family = AF_INET; server.sin_port = htons(port); if ((hp = gethostbyname(host)) == NULL) { fprintf(stderr, "Unknown server address\n"); exit(1); } bcopy(hp->h_addr, (char *)&server.sin_addr, hp->h_length); // Connecting to the server if (connect (sd, (struct sockaddr *)&server, sizeof(server)) == -1) { fprintf(stderr, "Can't connect to server\n"); perror("connect"); exit(1); } printf("Connected: Server Name: %s\n", hp->h_name); pptr = hp->h_addr_list; printf("\t\tIP Address: %s\n", inet_ntop(hp->h_addrtype, *pptr, str, sizeof(str))); while(1){ printf("Transmiting:\n"); for(;;) { // Transmit data through the socket send(sd, sbuf, strlen(sbuf), 0); sleep(12); } } fflush(stdout); close (sd); return (0); }
Code:#include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <stdlib.h> #include <strings.h> #include <arpa/inet.h> #include <unistd.h> #define SERVER_TCP_PORT 7000 // Default port #define BUFLEN 80 //Buffer length #define TRUE 1 #define LISTENQ 5 #define MAXLINE 4096 // Function Prototypes static void SystemFatal(const char* ); int main (int argc, char **argv) { int i, maxi, nready, bytes_to_read, arg; int listen_sd, new_sd, sockfd, client_len, port, maxfd, client[FD_SETSIZE]; struct sockaddr_in server, client_addr; char *bp, buf[BUFLEN]; ssize_t n; fd_set rset, allset; switch(argc) { case 1: port = SERVER_TCP_PORT; // Use the default port break; case 2: port = atoi(argv[1]); // Get user specified port break; default: fprintf(stderr, "Usage: %s [port]\n", argv[0]); exit(1); } // Create a stream socket if ((listen_sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) SystemFatal("Cannot Create Socket!"); // set SO_REUSEADDR so port can be resused imemediately after exit, i.e., after CTRL-c arg = 1; if (setsockopt (listen_sd, SOL_SOCKET, SO_REUSEADDR, &arg, sizeof(arg)) == -1) SystemFatal("setsockopt"); // Bind an address to the socket bzero((char *)&server, sizeof(struct sockaddr_in)); server.sin_family = AF_INET; server.sin_port = htons(port); server.sin_addr.s_addr = htonl(INADDR_ANY); // Accept connections from any client if (bind(listen_sd, (struct sockaddr *)&server, sizeof(server)) == -1) SystemFatal("bind error"); // Listen for connections // queue up to LISTENQ connect requests listen(listen_sd, LISTENQ); maxfd = listen_sd; // initialize maxi = -1; // index into client[] array for (i = 0; i < FD_SETSIZE; i++) client[i] = -1; // -1 indicates available entry FD_ZERO(&allset); FD_SET(listen_sd, &allset); while (TRUE) { rset = allset; // structure assignment nready = select(maxfd + 1, &rset, NULL, NULL, NULL); if (FD_ISSET(listen_sd, &rset)) // new client connection { client_len = sizeof(client_addr); if ((new_sd = accept(listen_sd, (struct sockaddr *) &client_addr, &client_len)) == -1) SystemFatal("accept error"); printf(" Remote Address: %s\n", inet_ntoa(client_addr.sin_addr)); for (i = 0; i < FD_SETSIZE; i++) if (client[i] < 0) { client[i] = new_sd; // save descriptor break; } if (i == FD_SETSIZE) { printf ("Too many clients\n"); exit(1); } FD_SET (new_sd, &allset); // add new descriptor to set if (new_sd > maxfd) maxfd = new_sd; // for select if (i > maxi) maxi = i; // new max index in client[] array if (--nready <= 0) continue; // no more readable descriptors } for (i = 0; i <= maxi; i++) // check all clients for data { if ((sockfd = client[i]) < 0) continue; if (FD_ISSET(sockfd, &rset)) { for(;;) { bp = buf; bytes_to_read = BUFLEN; while ((n = read(sockfd, bp, bytes_to_read)) > 0) { bp += n; bytes_to_read -= n; } printf("%s",buf); } if (n == 0) // connection closed by client { printf(" Remote Address: %s closed connection\n", inet_ntoa(client_addr.sin_addr)); close(sockfd); FD_CLR(sockfd, &allset); client[i] = -1; } if (--nready <= 0) break; // no more readable descriptors } } } return(0); } // Prints the error stored in errno and aborts the program. static void SystemFatal(const char* message) { perror (message); exit (EXIT_FAILURE); }
Originally Posted by lantzvillian
