Linux Socket Programming-UDP

The following is the code for the UDP server:

/* SERVER.C */#include <stdio.h> #include <string.h> #include <netinet/in.h> #include <arpa/inet.h > #include <ctype.h> #include "wrap.h" #define MAXLINE 80#define serv_port 8000int Main (void) {struct sockaddr_in SERVADDR, cliaddr;socklen_t cliaddr_len;int sockfd;char buf[maxline];char str[inet_addrstrlen];int i, N;SOCKFD = Wrap_ Socket (af_inet, SOCK_DGRAM, 0); Bzero (&servaddr, sizeof (SERVADDR)); servaddr.sin_family = Af_inet;servaddr.sin_ ADDR.S_ADDR = htonl (inaddr_any); servaddr.sin_port = Htons (Serv_port); Wrap_bind (SOCKFD, (struct sockaddr*) & SERVADDR, sizeof (SERVADDR));p rintf ("accepting connections ... \ n"); while (1) {Cliaddr_len = sizeof (CLIADDR); n = recvfrom (SOCKFD, buf, MAXLINE, 0, (struct sockaddr *) &cliaddr, &cliaddr_len); if (n = =-1) {perr_exit ("Recvfrom error");} printf ("received from%s at Port%d\n", Inet_ntop (Af_inet, &cliaddr.sin_addr, str, sizeof (STR)), Ntohs (cliaddr.sin_ Port)); for (i = 0; i < n; ++i) {Buf[i] = ToUpper (Buf[i]);} n = sendto (sOCKFD, buf, N, 0, (struct sockaddr *) &cliaddr, sizeof (CLIADDR)), if (n = =-1) perr_exit ("SendTo error!");}} 

Client code:

/* client.c */#include <stdio.h> #include <string.h> #include <unistd.h> #include <netinet/in.h > #include <arpa/inet.h> #include "wrap.h" #define MAXLINE 80#define serv_port 8000int Main (int argc, char *argv[] {struct sockaddr_in servaddr;int sockfd, N;char buf[maxline];char str[inet_addrstrlen];socklen_t SERVADDR_LEN;SOCKFD = Wrap_socket (af_inet, SOCK_DGRAM, 0); Bzero (&servaddr, sizeof (SERVADDR)); servaddr.sin_family = Af_inet;inet_pton (Af_inet, "127.0.0.1", &servaddr.sin_addr); servaddr.sin_port = Htons (Serv_port); while (Fgets (buf, MAXLINE, stdin) ! = NULL) {n = sendto (SOCKFD, buf, strlen (BUF), 0, (struct sockaddr *) &servaddr, sizeof (SERVADDR)), if (n = =-1) perr_exit ( "SendTo error") n = recvfrom (SOCKFD, buf, MAXLINE, 0, NULL, 0), if (n = =-1) perr_exit ("Recvfrom error"); Wrap_write (Stdout_f Ileno, buf, n);} Wrap_close (SOCKFD); return 0;}

Because the server and the client do not have the conditions to establish a connection and then communicate, the server can have concurrency capabilities.

Use CTRL + C to close the server, and then run server,client to contact the server.

Linux Socket Programming-UDP