New function to test for multicast addresses that must not be forwarded.

diff --git a/lib/packets.h b/lib/packets.h
index adda6bd..7f6bd42 100644 (file)
--- a/lib/packets.h
+++ b/lib/packets.h
@@ -89,6 +89,17 @@ static inline void eth_addr_random(uint8_t ea[ETH_ADDR_LEN])
     ea[0] &= ~1;                /* Unicast. */
     ea[0] |= 2;                 /* Private. */
 }
+/* Returns true if 'ea' is a reserved multicast address, that a bridge must
+ * never forward, false otherwise. */
+static inline bool eth_addr_is_reserved(const uint8_t ea[ETH_ADDR_LEN])
+{
+    return (ea[0] == 0x01
+            && ea[1] == 0x80
+            && ea[2] == 0xc2
+            && ea[3] == 0x00
+            && ea[4] == 0x00
+            && (ea[5] & 0xf0) == 0x00);
+}
 
 #define ETH_ADDR_FMT                                                    \
     "%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8