the_Foundation [main]

diff --git a/include/the_Foundation/address.h b/include/the_Foundation/address.h
index e2e4edf..b715d98 100644
--- a/include/the_Foundation/address.h
+++ b/include/the_Foundation/address.h
@@ -47,8 +47,18 @@ enum iSocketType {
     udp_SocketType,
 };
 
-iAddress *  newBroadcast_Address(uint16_t port);
-iAddress *  newSockAddr_Address (const void *sockAddr, size_t sockAddrSize, enum iSocketType socketType);
+iAddress *  newBroadcast_Address    (uint16_t port); /* 255.255.255.255 */
+iAddress *  newSockAddr_Address     (const void *sockAddr, size_t sockAddrSize, enum iSocketType socketType);
+
+/**
+ * Makes a UDP broadcast address for the interface that owns this address.
+ *
+ * @param port  UDP port number for broadcasting.
+ *
+ * @return A new Address instance (ownership given to caller), or NULL if not applicable (IPv6,
+ * loopback, point-to-point).
+ */
+iAddress *  makeBroadcast_Address   (const iAddress *, uint16_t port);
 
 void        init_Address        (iAddress *);
 void        deinit_Address      (iAddress *);
diff --git a/src/address.c b/src/address.c
index a4c28d0..9d07354 100644
--- a/src/address.c
+++ b/src/address.c
@@ -46,6 +46,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</small>
 #  include <arpa/inet.h>
 #  include <netinet/in.h>
 #  include <ifaddrs.h>
+#  include <net/if.h>
 #endif
 
 enum iAddressFlag {
@@ -161,6 +162,39 @@ iAddress *newBroadcast_Address(uint16_t port) {
     return d;
 }
 
+iAddress *makeBroadcast_Address(const iAddress *d, uint16_t port) {
+#if !defined (iPlatformWindows)
+    waitForFinished_Address(d);
+    if (!d->info || d->info->ai_family != AF_INET) {
+        return NULL; /* not an IPv4 address */
+    }
+    /* Find the network interface that owns this address and use its broadcast address.
+       On macOS/BSD, sending to 255.255.255.255 from an INADDR_ANY socket fails with
+       EADDRNOTAVAIL because the kernel requires a specific source interface for limited
+       broadcast. On Linux it works, but using per-interface broadcast addresses is
+       more correct on multi-homed hosts regardless of platform. */
+    const struct in_addr inputAddr =
+        ((const struct sockaddr_in *) d->info->ai_addr)->sin_addr;
+    struct ifaddrs *ifs = NULL;
+    if (getifaddrs(&ifs) == 0) {
+        for (const struct ifaddrs *i = ifs; i; i = i->ifa_next) {
+            if (!i->ifa_addr || i->ifa_addr->sa_family != AF_INET) continue;
+            if (!(i->ifa_flags & IFF_BROADCAST) || !i->ifa_broadaddr) continue;
+            const struct in_addr ifAddr =
+                ((const struct sockaddr_in *) i->ifa_addr)->sin_addr;
+            if (ifAddr.s_addr != inputAddr.s_addr) continue;
+            struct sockaddr_in ba = *(const struct sockaddr_in *) i->ifa_broadaddr;
+            ba.sin_port = htons(port);
+            freeifaddrs(ifs);
+            return newSockAddr_Address(&ba, sizeof(ba), udp_SocketType);
+        }
+        freeifaddrs(ifs);
+    }
+    return NULL; /* no broadcast-capable interface found for this address */
+#endif
+    return NULL;
+}
+
 iAddress *newSockAddr_Address(const void *     sockAddr,
                               size_t           sockAddrSize,
                               enum iSocketType socketType) {
diff --git a/tests/t_network.c b/tests/t_network.c
index 02bc00b..e9521cd 100644
--- a/tests/t_network.c
+++ b/tests/t_network.c
@@ -279,8 +279,12 @@ int main(int argc, char *argv[]) {
         printf("%zu network interfaces:\n", size_ObjectList(ifs));
         iConstForEach(ObjectList, i, ifs) {
             iString *str = toString_Address(i.object);
-            printf("- %s\n", cstr_String(str));
+            iAddress *broad = makeBroadcast_Address(i.object, 0);
+            printf("- %s (broadcast: %s)\n",
+                   cstr_String(str),
+                   broad ? cstrCollect_String(toString_Address(broad)) : "n/a");
             delete_String(str);
+            iRelease(broad);
         }
         iRelease(ifs);
     }