sockets/i6d_ucase_cl.c

+/* i6d_ucase_cl.c
+
+   Client for i6d_ucase_sv.c: send each command-line argument as a datagram to
+   the server, and then display the contents of the server's response datagram.
+*/
 #include "i6d_ucase.h"
 
 int
 main(int argc, char *argv[])
 {
     struct sockaddr_in6 svaddr;
     int sfd, j;
     size_t msgLen;
     ssize_t numBytes;
     char resp[BUF_SIZE];
 
     if (argc < 3 || strcmp(argv[1], "--help") == 0)
         usageErr("%s host-address msg...\n", argv[0]);
 
+    /* Create a datagram socket; send to an address in the IPv6 domain */
+
     sfd = socket(AF_INET6, SOCK_DGRAM, 0);      /* Create client socket */
     if (sfd == -1)
         errExit("socket");
 
     memset(&svaddr, 0, sizeof(struct sockaddr_in6));
     svaddr.sin6_family = AF_INET6;
     svaddr.sin6_port = htons(PORT_NUM);
     if (inet_pton(AF_INET6, argv[1], &svaddr.sin6_addr) <= 0)
         fatal("inet_pton failed for address '%s'", argv[1]);
 
     /* Send messages to server; echo responses on stdout */
 
     for (j = 2; j < argc; j++) {
         msgLen = strlen(argv[j]);
         if (sendto(sfd, argv[j], msgLen, 0, (struct sockaddr *) &svaddr,
                     sizeof(struct sockaddr_in6)) != msgLen)
             fatal("sendto");
 
         numBytes = recvfrom(sfd, resp, BUF_SIZE, 0, NULL, NULL);
         if (numBytes == -1)
             errExit("recvfrom");
 
         printf("Response %d: %.*s\n", j - 1, (int) numBytes, resp);
     }
 
     exit(EXIT_SUCCESS);
 }