Handle overlong frames like runt frames

ethertype-dump.c

@@ -82,6 +82,14 @@ int main(int argc, char **argv) {
 			continue;
 		}
 
+		if (frame_length > 1522) {
+			errno = 0;
+			if (printf("Overlong frame (%zdB)\n", frame_length) == -1) {
+				err(1, "printf");
+			}
+			continue;
+		}
+
 		// Extract the MACs
 		// 012345 012345
 		// dest   source