Aggiunto esempio di client daytime basato su UDP.

[gapil.git] / listati / UDP_daytime.c

diff --git a/listati/UDP_daytime.c b/listati/UDP_daytime.c
new file mode 100644 (file)
index 0000000..838678f
--- /dev/null
+++ b/listati/UDP_daytime.c
@@ -0,0 +1,43 @@
+int main(int argc, char *argv[])
+{
+    int sock;
+    int i, nread;
+    struct sockaddr_in addr;
+    char buffer[MAXLINE];
+    ...
+    /* create socket */
+    if ( (sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+       perror("Socket creation error");
+       return -1;
+    }
+    /* initialize address */
+    memset((void *) &addr, 0, sizeof(addr));    /* clear server address */
+    addr.sin_family = AF_INET;                  /* address type is INET */
+    addr.sin_port = htons(13);                  /* daytime port is 13 */
+    /* build address using inet_pton */
+    if ( (inet_pton(AF_INET, argv[optind], &addr.sin_addr)) <= 0) {
+       perror("Address creation error");
+       return -1;
+    }
+    /* send request packet */
+    nread = sendto(sock, NULL, 0, 0, (struct sockaddr *)&addr, sizeof(addr));
+    if (nread < 0) {
+       perror("Request error");
+       return -1;
+    }
+    nread = recvfrom(sock, buffer, MAXLINE, 0, NULL, NULL);
+    if (nread < 0) {
+       perror("Read error");
+       return -1;
+    }
+    /* print results */
+    if (nread > 0) {
+       buffer[nread]=0;
+       if (fputs(buffer, stdout) == EOF) {          /* write daytime */
+           perror("fputs error");
+           return -1;
+       }
+    }
+    /* normal exit */
+    return 0;
+}