1 files changed, 74 insertions, 0 deletions
diff --git a/src/broadcaster.c b/src/broadcaster.c
new file mode 100644
index 0000000..9c02f79
--- /dev/null
+++ b/src/broadcaster.c
@@ -0,0 +1,74 @@
+/*
+** 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>
+
+#include "common.h"
+
+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;
+
+    // assemble packet
+    if (argc < 3 || argc > 4) {
+        fprintf(stderr,"usage: broadcaster hostname task [message]\n");
+        exit(1);
+    }
+    char buf[MAXBUFLEN],
+      *task = argv[2],
+      *message = (argc == 4) ? argv[3] : NULL;
+    int task_len = strlen(task),
+      total_len = task_len + 1 + strlen(message);
+    if (total_len > MAXBUFLEN) {
+      fprintf(stderr,"payload to long: max %d bytes, was %d\n", MAXBUFLEN, total_len);
+      exit(1);
+    }
+    strcpy(buf, task);
+    buf[task_len] = 0;
+    strcpy(buf + 1 + task_len, message);
+
+    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, buf, total_len, 0,
+             (struct sockaddr *)&their_addr, sizeof their_addr)) == -1) {
+        perror("sendto");
+        exit(1);
+    }
+
+    return 0;
+}