batman-adv: Explicitly mark the common header structure

All batman-adv packets have a common 3 byte header. It can be used to share
some code between different code paths, but it was never explicit stated that
this header has to be always the same for all packets. Therefore, new code
changes always have the problem that they may accidently introduce regressions
by moving some elements around.

A new structure is introduced that contains the common header and makes it
easier visible that these 3 bytes have to be the same for all on-wire packets.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

net/batman-adv/bat_iv_ogm.c

@@ -38,10 +38,10 @@ void bat_ogm_init(struct hard_iface *hard_iface)
 	hard_iface->packet_buff = kmalloc(hard_iface->packet_len, GFP_ATOMIC);
 
 	batman_ogm_packet = (struct batman_ogm_packet *)hard_iface->packet_buff;
-	batman_ogm_packet->packet_type = BAT_OGM;
-	batman_ogm_packet->version = COMPAT_VERSION;
+	batman_ogm_packet->header.packet_type = BAT_OGM;
+	batman_ogm_packet->header.version = COMPAT_VERSION;
+	batman_ogm_packet->header.ttl = 2;
 	batman_ogm_packet->flags = NO_FLAGS;
-	batman_ogm_packet->ttl = 2;
 	batman_ogm_packet->tq = TQ_MAX_VALUE;
 	batman_ogm_packet->tt_num_changes = 0;
 	batman_ogm_packet->ttvn = 0;
@@ -53,7 +53,7 @@ void bat_ogm_init_primary(struct hard_iface *hard_iface)
 
 	batman_ogm_packet = (struct batman_ogm_packet *)hard_iface->packet_buff;
 	batman_ogm_packet->flags = PRIMARIES_FIRST_HOP;
-	batman_ogm_packet->ttl = TTL;
+	batman_ogm_packet->header.ttl = TTL;
 }
 
 void bat_ogm_update_mac(struct hard_iface *hard_iface)
@@ -137,7 +137,7 @@ static void bat_ogm_send_to_if(struct forw_packet *forw_packet,
 			fwd_str, (packet_num > 0 ? "aggregated " : ""),
 			batman_ogm_packet->orig,
 			ntohl(batman_ogm_packet->seqno),
-			batman_ogm_packet->tq, batman_ogm_packet->ttl,
+			batman_ogm_packet->tq, batman_ogm_packet->header.ttl,
 			(batman_ogm_packet->flags & DIRECTLINK ?
 			 "on" : "off"),
 			batman_ogm_packet->ttvn, hard_iface->net_dev->name,
@@ -188,7 +188,7 @@ void bat_ogm_emit(struct forw_packet *forw_packet)
 
 	/* multihomed peer assumed */
 	/* non-primary OGMs are only broadcasted on their interface */
-	if ((directlink && (batman_ogm_packet->ttl == 1)) ||
+	if ((directlink && (batman_ogm_packet->header.ttl == 1)) ||
 	    (forw_packet->own && (forw_packet->if_incoming != primary_if))) {
 
 		/* FIXME: what about aggregated packets ? */
@@ -198,7 +198,7 @@ void bat_ogm_emit(struct forw_packet *forw_packet)
 			(forw_packet->own ? "Sending own" : "Forwarding"),
 			batman_ogm_packet->orig,
 			ntohl(batman_ogm_packet->seqno),
-			batman_ogm_packet->ttl,
+			batman_ogm_packet->header.ttl,
 			forw_packet->if_incoming->net_dev->name,
 			forw_packet->if_incoming->net_dev->dev_addr);
 
@@ -272,7 +272,7 @@ static bool bat_ogm_can_aggregate(const struct batman_ogm_packet
 		 * are flooded through the net  */
 		if ((!directlink) &&
 		    (!(batman_ogm_packet->flags & DIRECTLINK)) &&
-		    (batman_ogm_packet->ttl != 1) &&
+		    (batman_ogm_packet->header.ttl != 1) &&
 
 		    /* own packets originating non-primary
 		     * interfaces leave only that interface */
@@ -285,7 +285,7 @@ static bool bat_ogm_can_aggregate(const struct batman_ogm_packet
 		/* if the incoming packet is sent via this one
 		 * interface only - we still can aggregate */
 		if ((directlink) &&
-		    (new_batman_ogm_packet->ttl == 1) &&
+		    (new_batman_ogm_packet->header.ttl == 1) &&
 		    (forw_packet->if_incoming == if_incoming) &&
 
 		    /* packets from direct neighbors or
@@ -471,18 +471,18 @@ static void bat_ogm_forward(struct orig_node *orig_node,
 	uint8_t in_tq, in_ttl, tq_avg = 0;
 	uint8_t tt_num_changes;
 
-	if (batman_ogm_packet->ttl <= 1) {
+	if (batman_ogm_packet->header.ttl <= 1) {
 		bat_dbg(DBG_BATMAN, bat_priv, "ttl exceeded\n");
 		return;
 	}
 
 	router = orig_node_get_router(orig_node);
 
 	in_tq = batman_ogm_packet->tq;
-	in_ttl = batman_ogm_packet->ttl;
+	in_ttl = batman_ogm_packet->header.ttl;
 	tt_num_changes = batman_ogm_packet->tt_num_changes;
 
-	batman_ogm_packet->ttl--;
+	batman_ogm_packet->header.ttl--;
 	memcpy(batman_ogm_packet->prev_sender, ethhdr->h_source, ETH_ALEN);
 
 	/* rebroadcast tq of our best ranking neighbor to ensure the rebroadcast
@@ -494,7 +494,8 @@ static void bat_ogm_forward(struct orig_node *orig_node,
 			batman_ogm_packet->tq = router->tq_avg;
 
 			if (router->last_ttl)
-				batman_ogm_packet->ttl = router->last_ttl - 1;
+				batman_ogm_packet->header.ttl =
+					router->last_ttl - 1;
 		}
 
 		tq_avg = router->tq_avg;
@@ -510,7 +511,7 @@ static void bat_ogm_forward(struct orig_node *orig_node,
 		"Forwarding packet: tq_orig: %i, tq_avg: %i, "
 		"tq_forw: %i, ttl_orig: %i, ttl_forw: %i\n",
 		in_tq, tq_avg, batman_ogm_packet->tq, in_ttl - 1,
-		batman_ogm_packet->ttl);
+		batman_ogm_packet->header.ttl);
 
 	batman_ogm_packet->seqno = htonl(batman_ogm_packet->seqno);
 	batman_ogm_packet->tt_crc = htons(batman_ogm_packet->tt_crc);
@@ -642,8 +643,8 @@ static void bat_ogm_orig_update(struct bat_priv *bat_priv,
 	spin_unlock_bh(&neigh_node->tq_lock);
 
 	if (!is_duplicate) {
-		orig_node->last_ttl = batman_ogm_packet->ttl;
-		neigh_node->last_ttl = batman_ogm_packet->ttl;
+		orig_node->last_ttl = batman_ogm_packet->header.ttl;
+		neigh_node->last_ttl = batman_ogm_packet->header.ttl;
 	}
 
 	bonding_candidate_add(orig_node, neigh_node);
@@ -683,7 +684,7 @@ static void bat_ogm_orig_update(struct bat_priv *bat_priv,
 	/* I have to check for transtable changes only if the OGM has been
 	 * sent through a primary interface */
 	if (((batman_ogm_packet->orig != ethhdr->h_source) &&
-	     (batman_ogm_packet->ttl > 2)) ||
+	     (batman_ogm_packet->header.ttl > 2)) ||
 	    (batman_ogm_packet->flags & PRIMARIES_FIRST_HOP))
 		tt_update_orig(bat_priv, orig_node, tt_buff,
 			       batman_ogm_packet->tt_num_changes,
@@ -918,7 +919,7 @@ static void bat_ogm_process(const struct ethhdr *ethhdr,
 	 * packet in an aggregation.  Here we expect that the padding
 	 * is always zero (or not 0x01)
 	 */
-	if (batman_ogm_packet->packet_type != BAT_OGM)
+	if (batman_ogm_packet->header.packet_type != BAT_OGM)
 		return;
 
 	/* could be changed by schedule_own_packet() */
@@ -938,8 +939,8 @@ static void bat_ogm_process(const struct ethhdr *ethhdr,
 		batman_ogm_packet->prev_sender, batman_ogm_packet->seqno,
 		batman_ogm_packet->ttvn, batman_ogm_packet->tt_crc,
 		batman_ogm_packet->tt_num_changes, batman_ogm_packet->tq,
-		batman_ogm_packet->ttl, batman_ogm_packet->version,
-		has_directlink_flag);
+		batman_ogm_packet->header.ttl,
+		batman_ogm_packet->header.version, has_directlink_flag);
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
@@ -966,10 +967,10 @@ static void bat_ogm_process(const struct ethhdr *ethhdr,
 	}
 	rcu_read_unlock();
 
-	if (batman_ogm_packet->version != COMPAT_VERSION) {
+	if (batman_ogm_packet->header.version != COMPAT_VERSION) {
 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Drop packet: incompatible batman version (%i)\n",
-			batman_ogm_packet->version);
+			batman_ogm_packet->header.version);
 		return;
 	}
 
@@ -1091,7 +1092,7 @@ static void bat_ogm_process(const struct ethhdr *ethhdr,
 	if (is_bidirectional &&
 	    (!is_duplicate ||
 	     ((orig_node->last_real_seqno == batman_ogm_packet->seqno) &&
-	      (orig_node->last_ttl - 3 <= batman_ogm_packet->ttl))))
+	      (orig_node->last_ttl - 3 <= batman_ogm_packet->header.ttl))))
 		bat_ogm_orig_update(bat_priv, orig_node, ethhdr,
 				    batman_ogm_packet, if_incoming,
 				    tt_buff, is_duplicate);

net/batman-adv/hard-interface.c

@@ -590,17 +590,17 @@ static int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 
 	batman_ogm_packet = (struct batman_ogm_packet *)skb->data;
 
-	if (batman_ogm_packet->version != COMPAT_VERSION) {
+	if (batman_ogm_packet->header.version != COMPAT_VERSION) {
 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Drop packet: incompatible batman version (%i)\n",
-			batman_ogm_packet->version);
+			batman_ogm_packet->header.version);
 		goto err_free;
 	}
 
 	/* all receive handlers return whether they received or reused
 	 * the supplied skb. if not, we have to free the skb. */
 
-	switch (batman_ogm_packet->packet_type) {
+	switch (batman_ogm_packet->header.packet_type) {
 		/* batman originator packet */
 	case BAT_OGM:
 		ret = recv_bat_ogm_packet(skb, hard_iface);

net/batman-adv/icmp_socket.c

@@ -191,7 +191,7 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
 		goto free_skb;
 	}
 
-	if (icmp_packet->packet_type != BAT_ICMP) {
+	if (icmp_packet->header.packet_type != BAT_ICMP) {
 		bat_dbg(DBG_BATMAN, bat_priv,
 			"Error - can't send packet from char device: "
 			"got bogus packet type (expected: BAT_ICMP)\n");
@@ -209,9 +209,9 @@ static ssize_t bat_socket_write(struct file *file, const char __user *buff,
 
 	icmp_packet->uid = socket_client->index;
 
-	if (icmp_packet->version != COMPAT_VERSION) {
+	if (icmp_packet->header.version != COMPAT_VERSION) {
 		icmp_packet->msg_type = PARAMETER_PROBLEM;
-		icmp_packet->version = COMPAT_VERSION;
+		icmp_packet->header.version = COMPAT_VERSION;
 		bat_socket_add_packet(socket_client, icmp_packet, packet_len);
 		goto free_skb;
 	}

net/batman-adv/packet.h

@@ -90,10 +90,14 @@ enum tt_client_flags {
 	TT_CLIENT_PENDING = 1 << 10
 };
 
-struct batman_ogm_packet {
+struct batman_header {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
 	uint8_t  ttl;
+} __packed;
+
+struct batman_ogm_packet {
+	struct batman_header header;
 	uint8_t  flags;    /* 0x40: DIRECTLINK flag, 0x20 VIS_SERVER flag... */
 	uint32_t seqno;
 	uint8_t  orig[6];
@@ -108,9 +112,7 @@ struct batman_ogm_packet {
 #define BATMAN_OGM_LEN sizeof(struct batman_ogm_packet)
 
 struct icmp_packet {
-	uint8_t  packet_type;
-	uint8_t  version;  /* batman version field */
-	uint8_t  ttl;
+	struct batman_header header;
 	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  dst[6];
 	uint8_t  orig[6];
@@ -124,9 +126,7 @@ struct icmp_packet {
 /* icmp_packet_rr must start with all fields from imcp_packet
  * as this is assumed by code that handles ICMP packets */
 struct icmp_packet_rr {
-	uint8_t  packet_type;
-	uint8_t  version;  /* batman version field */
-	uint8_t  ttl;
+	struct batman_header header;
 	uint8_t  msg_type; /* see ICMP message types above */
 	uint8_t  dst[6];
 	uint8_t  orig[6];
@@ -137,17 +137,13 @@ struct icmp_packet_rr {
 } __packed;
 
 struct unicast_packet {
-	uint8_t  packet_type;
-	uint8_t  version;  /* batman version field */
-	uint8_t  ttl;
+	struct batman_header header;
 	uint8_t  ttvn; /* destination translation table version number */
 	uint8_t  dest[6];
 } __packed;
 
 struct unicast_frag_packet {
-	uint8_t  packet_type;
-	uint8_t  version;  /* batman version field */
-	uint8_t  ttl;
+	struct batman_header header;
 	uint8_t  ttvn; /* destination translation table version number */
 	uint8_t  dest[6];
 	uint8_t  flags;
@@ -157,18 +153,14 @@ struct unicast_frag_packet {
 } __packed;
 
 struct bcast_packet {
-	uint8_t  packet_type;
-	uint8_t  version;  /* batman version field */
-	uint8_t  ttl;
+	struct batman_header header;
 	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 */
+	struct batman_header header;
 	uint8_t  vis_type;	 /* which type of vis-participant sent this? */
 	uint32_t seqno;		 /* sequence number */
 	uint8_t  entries;	 /* number of entries behind this struct */
@@ -179,9 +171,7 @@ struct vis_packet {
 } __packed;
 
 struct tt_query_packet {
-	uint8_t  packet_type;
-	uint8_t  version;  /* batman version field */
-	uint8_t  ttl;
+	struct batman_header header;
 	/* the flag field is a combination of:
 	 * - TT_REQUEST or TT_RESPONSE
 	 * - TT_FULL_TABLE */
@@ -202,9 +192,7 @@ struct tt_query_packet {
 } __packed;
 
 struct roam_adv_packet {
-	uint8_t  packet_type;
-	uint8_t  version;
-	uint8_t  ttl;
+	struct batman_header header;
 	uint8_t  reserved;
 	uint8_t  dst[ETH_ALEN];
 	uint8_t  src[ETH_ALEN];

net/batman-adv/routing.c

@@ -320,7 +320,7 @@ static int recv_my_icmp_packet(struct bat_priv *bat_priv,
 	memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN);
 	memcpy(icmp_packet->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 	icmp_packet->msg_type = ECHO_REPLY;
-	icmp_packet->ttl = TTL;
+	icmp_packet->header.ttl = TTL;
 
 	send_skb_packet(skb, router->if_incoming, router->addr);
 	ret = NET_RX_SUCCESS;
@@ -376,7 +376,7 @@ static int recv_icmp_ttl_exceeded(struct bat_priv *bat_priv,
 	memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN);
 	memcpy(icmp_packet->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 	icmp_packet->msg_type = TTL_EXCEEDED;
-	icmp_packet->ttl = TTL;
+	icmp_packet->header.ttl = TTL;
 
 	send_skb_packet(skb, router->if_incoming, router->addr);
 	ret = NET_RX_SUCCESS;
@@ -441,7 +441,7 @@ int recv_icmp_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 		return recv_my_icmp_packet(bat_priv, skb, hdr_size);
 
 	/* TTL exceeded */
-	if (icmp_packet->ttl < 2)
+	if (icmp_packet->header.ttl < 2)
 		return recv_icmp_ttl_exceeded(bat_priv, skb);
 
 	/* get routing information */
@@ -460,7 +460,7 @@ int recv_icmp_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 	icmp_packet = (struct icmp_packet_rr *)skb->data;
 
 	/* decrement ttl */
-	icmp_packet->ttl--;
+	icmp_packet->header.ttl--;
 
 	/* route it */
 	send_skb_packet(skb, router->if_incoming, router->addr);
@@ -815,7 +815,7 @@ int route_unicast_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 	unicast_packet = (struct unicast_packet *)skb->data;
 
 	/* TTL exceeded */
-	if (unicast_packet->ttl < 2) {
+	if (unicast_packet->header.ttl < 2) {
 		pr_debug("Warning - can't forward unicast packet from %pM to "
 			 "%pM: ttl exceeded\n", ethhdr->h_source,
 			 unicast_packet->dest);
@@ -840,15 +840,15 @@ int route_unicast_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 
 	unicast_packet = (struct unicast_packet *)skb->data;
 
-	if (unicast_packet->packet_type == BAT_UNICAST &&
+	if (unicast_packet->header.packet_type == BAT_UNICAST &&
 	    atomic_read(&bat_priv->fragmentation) &&
 	    skb->len > neigh_node->if_incoming->net_dev->mtu) {
 		ret = frag_send_skb(skb, bat_priv,
 				    neigh_node->if_incoming, neigh_node->addr);
 		goto out;
 	}
 
-	if (unicast_packet->packet_type == BAT_UNICAST_FRAG &&
+	if (unicast_packet->header.packet_type == BAT_UNICAST_FRAG &&
 	    frag_can_reassemble(skb, neigh_node->if_incoming->net_dev->mtu)) {
 
 		ret = frag_reassemble_skb(skb, bat_priv, &new_skb);
@@ -867,7 +867,7 @@ int route_unicast_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 	}
 
 	/* decrement ttl */
-	unicast_packet->ttl--;
+	unicast_packet->header.ttl--;
 
 	/* route it */
 	send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
@@ -1041,7 +1041,7 @@ int recv_bcast_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 	if (is_my_mac(bcast_packet->orig))
 		goto out;
 
-	if (bcast_packet->ttl < 2)
+	if (bcast_packet->header.ttl < 2)
 		goto out;
 
 	orig_node = orig_hash_find(bat_priv, bcast_packet->orig);