feat: Parse command line argument of remote worker

Add command line argument parsing in remote worker
for allowing user to assign the IP address of the RabbitMQ broker.

Close #185.

src/remote_worker.c

@@ -6,23 +6,45 @@
  * "LICENSE" at the root of this distribution.
  */
 
+#include <getopt.h>
 #include "common.h"
 #include "constants.h"
 #include "dcurl.h"
 #include "remote_common.h"
 
-int main(int argc, char const *const *argv)
+int main(int argc, char *const *argv)
 {
     char trytes[TRANSACTION_TRYTES_LENGTH];
     char buf[4];
     int mwm;
+    int cmdOpt;
+    int optIdx;
+    const struct option longOpt[] = {{"broker", required_argument, NULL, 'b'},
+                                     {NULL, 0, NULL, 0}};
 
     amqp_connection_state_t conn;
     amqp_envelope_t envelope;
+    char *hostIP = NULL;
+
+    /* Parse the command line options */
+    /* TODO: Support macOS since getopt_long() is GNU extension */
+    while (1) {
+        cmdOpt = getopt_long(argc, argv, "b:", longOpt, &optIdx);
+        if (cmdOpt == -1)
+            break;
+
+        /* Invalid option */
+        if (cmdOpt == '?')
+            break;
+
+        if (cmdOpt == 'b') {
+            hostIP = optarg;
+        }
+    }
 
     dcurl_init();
 
-    if (!connect_broker(&conn, NULL))
+    if (!connect_broker(&conn, hostIP))
         goto fail;
 
     if (!set_consuming_queue(&conn, 1, "incoming_queue"))