1 files changed, 67 insertions, 0 deletions
diff --git a/broadcaster.c b/broadcaster.c
new file mode 100644
index 0000000..0e4eef5
--- /dev/null
+++ b/broadcaster.c
@@ -0,0 +1,67 @@
+/*
+** broadcaster.c -- a datagram "client" like talker.c, except
+**                  this one can broadcast
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#define SERVERPORT 4950    // the port users will be connecting to
+
+int main(int argc, char *argv[])
+{
+    int sockfd;
+    struct sockaddr_in their_addr; // connector's address information
+    struct hostent *he;
+    int numbytes;
+    int broadcast = 1;
+    //char broadcast = '1'; // if that doesn't work, try this
+
+    if (argc != 3) {
+        fprintf(stderr,"usage: broadcaster hostname message\n");
+        exit(1);
+    }
+
+    if ((he=gethostbyname(argv[1])) == NULL) {  // get the host info
+        perror("gethostbyname");
+        exit(1);
+    }
+
+    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
+        perror("socket");
+        exit(1);
+    }
+
+    // this call is what allows broadcast packets to be sent:
+    if (setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &broadcast,
+        sizeof broadcast) == -1) {
+        perror("setsockopt (SO_BROADCAST)");
+        exit(1);
+    }
+
+    their_addr.sin_family = AF_INET;     // host byte order
+    their_addr.sin_port = htons(SERVERPORT); // short, network byte order
+    their_addr.sin_addr = *((struct in_addr *)he->h_addr);
+    memset(their_addr.sin_zero, '\0', sizeof their_addr.sin_zero);
+
+    if ((numbytes=sendto(sockfd, argv[2], strlen(argv[2]), 0,
+             (struct sockaddr *)&their_addr, sizeof their_addr)) == -1) {
+        perror("sendto");
+        exit(1);
+    }
+
+    printf("sent %d bytes to %s\n", numbytes,
+        inet_ntoa(their_addr.sin_addr));
+
+    close(sockfd);
+
+    return 0;
+}