sockets/ud_ucase_cl.c

+/* ud_ucase_cl.c
+
+   A UNIX domain client that communicates with the server in ud_ucase_sv.c.
+   This client sends each command-line argument as a datagram to the server,
+   and then displays the contents of the server's response datagram.
+*/
 #include "ud_ucase.h"
 
 int
 main(int argc, char *argv[])
 {
     struct sockaddr_un svaddr, claddr;
     int sfd, j;
     size_t msgLen;
     ssize_t numBytes;
     char resp[BUF_SIZE];
 
     if (argc < 2 || strcmp(argv[1], "--help") == 0)
         usageErr("%s msg...\n", argv[0]);
 
     /* Create client socket; bind to unique pathname (based on PID) */
 
     sfd = socket(AF_UNIX, SOCK_DGRAM, 0);
     if (sfd == -1)
         errExit("socket");
 
     memset(&claddr, 0, sizeof(struct sockaddr_un));
     claddr.sun_family = AF_UNIX;
     snprintf(claddr.sun_path, sizeof(claddr.sun_path),
             "/tmp/ud_ucase_cl.%ld", (long) getpid());
 
     if (bind(sfd, (struct sockaddr *) &claddr, sizeof(struct sockaddr_un)) == -1)
         errExit("bind");
 
     /* Construct address of server */
 
     memset(&svaddr, 0, sizeof(struct sockaddr_un));
     svaddr.sun_family = AF_UNIX;
     strncpy(svaddr.sun_path, SV_SOCK_PATH, sizeof(svaddr.sun_path) - 1);
 
     /* Send messages to server; echo responses on stdout */
 
     for (j = 1; j < argc; j++) {
         msgLen = strlen(argv[j]);       /* May be longer than BUF_SIZE */
         if (sendto(sfd, argv[j], msgLen, 0, (struct sockaddr *) &svaddr,
                 sizeof(struct sockaddr_un)) != msgLen)
             fatal("sendto");
 
         numBytes = recvfrom(sfd, resp, BUF_SIZE, 0, NULL, NULL);
+        /* Or equivalently: numBytes = recv(sfd, resp, BUF_SIZE, 0);
+                        or: numBytes = read(sfd, resp, BUF_SIZE); */
         if (numBytes == -1)
             errExit("recvfrom");
         printf("Response %d: %.*s\n", j, (int) numBytes, resp);
     }
 
     remove(claddr.sun_path);            /* Remove client socket pathname */
     exit(EXIT_SUCCESS);
 }