Save maximum length in packet buffers

1 files changed, 10 insertions, 4 deletions

diff --git a/src/packet.h b/src/packet.h
index df22dd6..09b6dc0 100644
--- a/src/packet.h
+++ b/src/packet.h
@@ -43,11 +43,17 @@ struct __attribute__((packed)) gp_babel_packet {
 	uint8_t tlv[];
 };
 
+struct gp_babel_packet_buf {
+	size_t max_len;
+	gp_babel_packet_t packet;
+};
+
 #define gp_babel_packet_alloca(size) ({ \
-			gp_babel_packet_t *__packet = alloca(sizeof(gp_babel_packet_t)+size); \
-			__packet->version = htons(GP_BABEL_VERSION);	\
-			__packet->len = 0;				\
-			__packet;					\
+			gp_babel_packet_buf_t *__buf = alloca(sizeof(gp_babel_packet_buf_t) + size - sizeof(gp_babel_packet_t)); \
+			__buf->max_len = size - sizeof(gp_babel_packet_t); \
+			__buf->packet.version = htons(GP_BABEL_VERSION); \
+			__buf->packet.len = 0;				\
+			__buf;						\
 		})
 
 static inline size_t gp_babel_packet_size(const gp_babel_packet_t *packet) {