batman-adv: Unify the first 3 bytes in each packet

The amount of duplicated code in the receive and routing code can be
reduced when all headers provide the packet type, version and ttl in the
same first bytes.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

Author: Antonio Quartulli

net/batman-adv/packet.h

@@ -34,7 +34,7 @@ enum bat_packettype {
 };
 
 /* this file is included by batctl which needs these defines */
-#define COMPAT_VERSION 12
+#define COMPAT_VERSION 14
 
 enum batman_flags {
 	PRIMARIES_FIRST_HOP = 1 << 4,
@@ -66,28 +66,29 @@ enum unicast_frag_flags {
 struct batman_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
+	uint8_t  ttl;
 	uint8_t  flags;    /* 0x40: DIRECTLINK flag, 0x20 VIS_SERVER flag... */
-	uint8_t  tq;
 	uint32_t seqno;
 	uint8_t  orig[6];
 	uint8_t  prev_sender[6];
-	uint8_t  ttl;
-	uint8_t  num_tt;
 	uint8_t  gw_flags;  /* flags related to gateway class */
-	uint8_t  align;
+	uint8_t  tq;
+	uint8_t  num_tt;
+	uint8_t  reserved;
 } __packed;
 
 #define BAT_PACKET_LEN sizeof(struct batman_packet)
 
 struct icmp_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
-	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  ttl;
+	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  dst[6];
 	uint8_t  orig[6];
 	uint16_t seqno;
 	uint8_t  uid;
+	uint8_t  reserved;
 } __packed;
 
 #define BAT_RR_LEN 16
@@ -97,8 +98,8 @@ struct icmp_packet {
 struct icmp_packet_rr {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
-	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  ttl;
+	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  dst[6];
 	uint8_t  orig[6];
 	uint16_t seqno;
@@ -110,35 +111,40 @@ struct icmp_packet_rr {
 struct unicast_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
-	uint8_t  dest[6];
 	uint8_t  ttl;
+	uint8_t  reserved;
+	uint8_t  dest[6];
 } __packed;
 
 struct unicast_frag_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
-	uint8_t  dest[6];
 	uint8_t  ttl;
+	uint8_t  reserved;
+	uint8_t  dest[6];
 	uint8_t  flags;
+	uint8_t  align;
 	uint8_t  orig[6];
 	uint16_t seqno;
 } __packed;
 
 struct bcast_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
-	uint8_t  orig[6];
 	uint8_t  ttl;
+	uint8_t  reserved;
 	uint32_t seqno;
+	uint8_t  orig[6];
 } __packed;
 
 struct vis_packet {
 	uint8_t  packet_type;
 	uint8_t  version;        /* batman version field */
+	uint8_t  ttl;		 /* TTL */
 	uint8_t  vis_type;	 /* which type of vis-participant sent this? */
-	uint8_t  entries;	 /* number of entries behind this struct */
 	uint32_t seqno;		 /* sequence number */
-	uint8_t  ttl;		 /* TTL */
+	uint8_t  entries;	 /* number of entries behind this struct */
+	uint8_t  reserved;
 	uint8_t  vis_orig[6];	 /* originator that announces its neighbors */
 	uint8_t  target_orig[6]; /* who should receive this packet */
 	uint8_t  sender_orig[6]; /* who sent or rebroadcasted this packet */