Save maximum length in packet buffers

5 files changed, 28 insertions, 21 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) {
diff --git a/src/send.c b/src/send.c
index cdeb07a..56685c3 100644
--- a/src/send.c
+++ b/src/send.c
@@ -44,22 +44,22 @@ static inline bool send_neigh(gmrf_t *gmrf, const gp_babel_neigh_t *neigh, const
 }
 
 void gp_babel_send_ack(gmrf_t *gmrf, gmrf_context_t *ctx, gp_babel_neigh_t *neigh, uint16_t nonce) {
-	gp_babel_packet_t *packet = gp_babel_packet_alloca(GP_BABEL_PACKET_MAX);
+	gp_babel_packet_buf_t *buf = gp_babel_packet_alloca(GP_BABEL_PACKET_MAX);
 
-	gp_babel_tlv_ack_t *ack = gp_babel_tlv_add(packet, GP_BABEL_PACKET_MAX, TLV_ACK, sizeof(gp_babel_tlv_ack_t));
+	gp_babel_tlv_ack_t *ack = gp_babel_tlv_add(buf, TLV_ACK, sizeof(gp_babel_tlv_ack_t));
 	if (!ack)
 		return;
 
 	ack->nonce = htons(nonce);
 
-	send_neigh(gmrf, neigh, packet);
+	send_neigh(gmrf, neigh, &buf->packet);
 }
 
-static void add_ihus(gmrf_t *gmrf, gp_babel_packet_t *packet, size_t max_len, const gp_babel_iface_t *iface) {
+static void add_ihus(gmrf_t *gmrf, gp_babel_packet_buf_t *buf, const gp_babel_iface_t *iface) {
 	const gp_babel_neigh_t *neigh;
 
 	for (neigh = iface->neighbours; neigh; neigh = neigh->next) {
-		gp_babel_tlv_ihu_t *ihu = gp_babel_tlv_add(packet, GP_BABEL_PACKET_MAX, TLV_IHU, sizeof(gp_babel_tlv_ihu_t)+sizeof(gmrf_addr_t));
+		gp_babel_tlv_ihu_t *ihu = gp_babel_tlv_add(buf, TLV_IHU, sizeof(gp_babel_tlv_ihu_t)+sizeof(gmrf_addr_t));
 		if (!ihu)
 			return;
 
@@ -74,25 +74,25 @@ static void add_ihus(gmrf_t *gmrf, gp_babel_packet_t *packet, size_t max_len, co
 void gp_babel_send_hellos(gmrf_t *gmrf, gmrf_context_t *ctx) {
 	gmrf_logf(gmrf, LOG_DEBUG, "sending hellos...");
 
-	gp_babel_packet_t *packet = gp_babel_packet_alloca(GP_BABEL_PACKET_MAX);
+	gp_babel_packet_buf_t *buf = gp_babel_packet_alloca(GP_BABEL_PACKET_MAX);
 
-	gp_babel_tlv_hello_t *hello = gp_babel_tlv_add(packet, GP_BABEL_PACKET_MAX, TLV_HELLO, sizeof(gp_babel_tlv_hello_t));
+	gp_babel_tlv_hello_t *hello = gp_babel_tlv_add(buf, TLV_HELLO, sizeof(gp_babel_tlv_hello_t));
 	if (!hello)
 		return;
 
 	hello->reserved = 0;
 	hello->interval = htons(GP_BABEL_HELLO_INTERVAL);
 
-	uint16_t len = packet->len;
+	uint16_t len = buf->packet.len;
 
 	gp_babel_iface_t *iface;
 	for (iface = ctx->interfaces; iface; iface = iface->next) {
 		hello->seqno = htons(iface->seqno++);
 
-		packet->len = len;
+		buf->packet.len = len;
 
-		add_ihus(gmrf, packet, GP_BABEL_PACKET_MAX, iface);
+		add_ihus(gmrf, buf, iface);
 
-		gmrf_iface_send_bc(gmrf, iface->gmrf_iface, packet, gp_babel_packet_size(packet));
+		gmrf_iface_send_bc(gmrf, iface->gmrf_iface, &buf->packet, gp_babel_packet_size(&buf->packet));
 	}
 }
diff --git a/src/tlv.c b/src/tlv.c
index 488f775..38232d1 100644
--- a/src/tlv.c
+++ b/src/tlv.c
@@ -57,18 +57,18 @@ bool gp_babel_tlv_parse(gmrf_t *gmrf, gmrf_context_t *ctx, const gp_babel_packet
 	return true;
 }
 
-void* gp_babel_tlv_add(gp_babel_packet_t *packet, size_t max_len, gp_babel_tlv_type_t type, size_t len) {
-	size_t pktlen = ntohs(packet->len);
+void* gp_babel_tlv_add(gp_babel_packet_buf_t *buf, gp_babel_tlv_type_t type, size_t len) {
+	size_t pktlen = ntohs(buf->packet.len);
 
-	if (pktlen+len+2 > max_len)
+	if (pktlen+len+2 > buf->max_len)
 		return NULL;
 
-	uint8_t *data = packet->tlv+pktlen+2;
+	uint8_t *data = buf->packet.tlv+pktlen+2;
 
 	data[-2] = type;
 	data[-1] = len;
 
-	packet->len = htons(pktlen+len+2);
+	buf->packet.len = htons(pktlen+len+2);
 
 	return data;
 }
diff --git a/src/tlv.h b/src/tlv.h
index d05a4a8..6c35129 100644
--- a/src/tlv.h
+++ b/src/tlv.h
@@ -57,7 +57,7 @@ typedef void (*gp_babel_tlv_cb)(gmrf_t *gmrf, gmrf_context_t *ctx, gp_babel_tlv_
 
 
 bool gp_babel_tlv_parse(gmrf_t *gmrf, gmrf_context_t *ctx, const gp_babel_packet_t *packet, gp_babel_tlv_cb cb, void *arg);
-void* gp_babel_tlv_add(gp_babel_packet_t *packet, size_t max_len, gp_babel_tlv_type_t type, size_t len);
+void* gp_babel_tlv_add(gp_babel_packet_buf_t *buf, gp_babel_tlv_type_t type, size_t len);
 
 
 #endif /* _GMRF_PROTO_BABEL_TLV_H_ */
diff --git a/src/types.h b/src/types.h
index ce3d99f..1d05c03 100644
--- a/src/types.h
+++ b/src/types.h
@@ -35,6 +35,7 @@ typedef struct __attribute__((packed)) gp_gabel_node_id {
 } gp_babel_node_id_t;
 
 typedef struct gp_babel_packet gp_babel_packet_t;
+typedef struct gp_babel_packet_buf gp_babel_packet_buf_t;
 typedef struct gp_babel_iface gp_babel_iface_t;
 typedef struct gp_babel_neigh gp_babel_neigh_t;