zbeacon.patch

diff --git a/src/zbeacon.c b/src/zbeacon.c
index 249c37c..7c5bc47 100644
--- a/src/zbeacon.c
+++ b/src/zbeacon.c
@@ -324,6 +324,7 @@ typedef struct {
     zframe_t *transmit;         //  Beacon transmit data
     zframe_t *filter;           //  Beacon filter data
     inaddr_t address;           //  Our own address
+    inaddr_t netmask;           //  Our own netmask
     inaddr_t broadcast;         //  Our broadcast address
 } agent_t;
 
@@ -471,6 +472,13 @@ s_get_interface (agent_t *self)
                     self->broadcast.sin_addr.s_addr
                         |= ~(((inaddr_t *) interface->ifa_netmask)->sin_addr.s_addr);
 
+                // If the returned broadcast address is the limited broadcast
+                // address, build the broadcast address from the source
+                // address and netmask.
+                if (self->broadcast.sin_addr.s_addr == INADDR_BROADCAST)
+                    self->broadcast.sin_addr.s_addr = self->address.sin_addr.s_addr
+                        | ~(((inaddr_t *) interface->ifa_netmask)->sin_addr.s_addr);
+
                 //  Keep track of the number of interfaces on this host
                 if (self->address.sin_addr.s_addr != ntohl (INADDR_LOOPBACK))
                     num_interfaces++;
@@ -535,6 +543,21 @@ s_get_interface (agent_t *self)
         zsys_socket_error ("siocgifbrdaddr");
 
     memcpy (&self->broadcast, ((inaddr_t *) &ifr.ifr_broadaddr), sizeof (inaddr_t));
+
+    self->broadcast.sin_port = htons (self->port_nbr);
+
+    // If the returned broadcast address is the limited broadcast
+    // address, build the broadcast address from the source
+    // address and netmask.
+    if (self->broadcast.sin_addr.s_addr == INADDR_BROADCAST) {
+        rc = ioctl (sock, SIOCGIFNETMASK, (caddr_t) &ifr, sizeof (struct ifreq));
+        if (rc == -1)
+            zsys_socket_error ("siocgifnetmask");
+        memcpy (&self->netmask, ((inaddr_t *) &ifr.ifr_netmask), sizeof (inaddr_t));
+        self->broadcast.sin_addr.s_addr = self->address.sin_addr.s_addr
+            | ~(self->netmask.sin_addr.s_addr);
+    }
+
     close (sock);
 
 #   elif defined (__WINDOWS__)