UNIX Network programming: UDP lack of flow control (improved version)

Now we look at the impact of UDP on datagram transmission without any traffic control. First we modify the DG_CLI function to send a fixed number of datagrams and no longer read from the standard input. As follows, it writes 2000 UDP datagrams of 1400 bytes in size to the server.

Client program CLI.C:

#include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <stdlib.h> #include <stdio.h> #include <errno.h> #includ 
                E <string.h> #define Serv_port 3333 #define MAXLINE 1024 #define ERR_EXIT (m) \ do \ {\ Perror (m); \ exit (exit_failure);  
\} while (0) typedef struct SOCKADDR SA; #define NDG/* Datagrams to send */#define DGLEN 1400/* length of each datagram/void Dg_c  
    Li (FILE *fp, int sockfd, const SA *pservaddr, socklen_t servlen) {int i;  
      
    Char Sendline[dglen];  
    for (i = 0; i < ndg i++) {sendto (SOCKFD, Sendline, Dglen, 0, pservaddr, Servlen);  
    int main (int argc, char **argv) {int sockfd;  
      
    struct sockaddr_in servaddr;  
  if (argc!= 2)      Err_exit ("Usage:udpcli <IPaddress>");  
    Bzero (&servaddr, sizeof (SERVADDR));  
    servaddr.sin_family = af_inet;  
    Servaddr.sin_port = htons (Serv_port);  
      
    Inet_pton (Af_inet, argv[1], &servaddr.sin_addr);  
      
    SOCKFD = socket (af_inet, SOCK_DGRAM, 0);  
      
    DG_CLI (stdin, SOCKFD, (SA *) &servaddr, sizeof (SERVADDR));  
Exit (0); }

We then modify the server program to accept the datagram and count it, and no longer send the datagram back to the customer. The following is the new Dg_echo function. When we terminate the server with a terminal break key (equivalent to sending it a SIGINT signal), the server displays the number of datagrams received and terminates.

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