batman-adv: create common header for ICMP packets

the icmp and the icmp_rr packets share the same initial
fields since they use the same code to be processed and
forwarded.

Extract the common fields and put them into a separate
struct so that future ICMP packets can be easily added
without bloating the packet definition.

However, keep the seqno field outside of the newly created
common header because future ICMP types may require a
bigger sequence number space.

This change breaks compatibility due to fields reordering
in the ICMP headers.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

1 files changed, 28 insertions, 10 deletions

diff --git a/net/batman-adv/packet.h b/net/batman-adv/packet.h
index aa46c27..65e723e 100644
--- a/net/batman-adv/packet.h
+++ b/net/batman-adv/packet.h
@@ -186,29 +186,47 @@ struct batadv_ogm_packet {
 
 #define BATADV_OGM_HLEN sizeof(struct batadv_ogm_packet)
 
-struct batadv_icmp_packet {
+/**
+ * batadv_icmp_header - common ICMP header
+ * @header: common batman header
+ * @msg_type: ICMP packet type
+ * @dst: address of the destination node
+ * @orig: address of the source node
+ * @uid: local ICMP socket identifier
+ */
+struct batadv_icmp_header {
 	struct batadv_header header;
 	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  dst[ETH_ALEN];
 	uint8_t  orig[ETH_ALEN];
-	__be16   seqno;
 	uint8_t  uid;
+};
+
+/**
+ * batadv_icmp_packet - ICMP packet
+ * @icmph: common ICMP header
+ * @reserved: not used - useful for alignment
+ * @seqno: ICMP sequence number
+ */
+struct batadv_icmp_packet {
+	struct batadv_icmp_header icmph;
 	uint8_t  reserved;
+	__be16   seqno;
 };
 
 #define BATADV_RR_LEN 16
 
-/* icmp_packet_rr must start with all fields from imcp_packet
- * as this is assumed by code that handles ICMP packets
+/**
+ * batadv_icmp_packet_rr - ICMP RouteRecord packet
+ * @icmph: common ICMP header
+ * @rr_cur: number of entries the rr array
+ * @seqno: ICMP sequence number
+ * @rr: route record array
  */
 struct batadv_icmp_packet_rr {
-	struct batadv_header header;
-	uint8_t  msg_type; /* see ICMP message types above */
-	uint8_t  dst[ETH_ALEN];
-	uint8_t  orig[ETH_ALEN];
-	__be16   seqno;
-	uint8_t  uid;
+	struct batadv_icmp_header icmph;
 	uint8_t  rr_cur;
+	__be16   seqno;
 	uint8_t  rr[BATADV_RR_LEN][ETH_ALEN];
 };