[PATCH BlueZ 4/4] mesh: Always relay messages from Low Power nodes

[Isak Westin <isak.westin@loytec.com>]

If we receive a message from one of our Low Power nodes, which is
encrypted using frendship credentials and where the destination is not
us, we must relay that message using master credentials.
See MshPRFv1.0.1 section 3.6.6.2.
---
 mesh/net.c | 47 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/mesh/net.c b/mesh/net.c
index 577121f30..a1b586a0b 100644
--- a/mesh/net.c
+++ b/mesh/net.c
@@ -1763,7 +1763,8 @@ not_for_friend:
 	return true;
 }
 
-static uint16_t key_id_to_net_idx(struct mesh_net *net, uint32_t net_key_id)
+static uint16_t key_id_to_net_idx(struct mesh_net *net,
+				uint32_t net_key_id, bool *frnd)
 {
 	struct mesh_subnet *subnet;
 	struct mesh_friend *friend;
@@ -1771,6 +1772,9 @@ static uint16_t key_id_to_net_idx(struct mesh_net *net, uint32_t net_key_id)
 	if (!net)
 		return NET_IDX_INVALID;
 
+	if (frnd)
+		*frnd = false;
+
 	subnet = l_queue_find(net->subnets, match_key_id,
 						L_UINT_TO_PTR(net_key_id));
 
@@ -1780,8 +1784,12 @@ static uint16_t key_id_to_net_idx(struct mesh_net *net, uint32_t net_key_id)
 	friend = l_queue_find(net->friends, match_friend_key_id,
 						L_UINT_TO_PTR(net_key_id));
 
-	if (friend)
+	if (friend) {
+		if (frnd)
+			*frnd = true;
+
 		return friend->net_idx;
+	}
 
 	friend = l_queue_find(net->negotiations, match_friend_key_id,
 						L_UINT_TO_PTR(net_key_id));
@@ -2078,7 +2086,7 @@ static bool ctl_received(struct mesh_net *net, uint32_t net_key_id,
 			return false;
 
 		print_packet("Rx-NET_OP_FRND_REQUEST", pkt, len);
-		net_idx = key_id_to_net_idx(net, net_key_id);
+		net_idx = key_id_to_net_idx(net, net_key_id, NULL);
 		friend_request(net, net_idx, src, pkt[0], pkt[1],
 				l_get_be32(pkt + 1) & 0xffffff,
 				l_get_be16(pkt + 5), pkt[7],
@@ -2269,7 +2277,8 @@ static void send_msg_pkt(struct mesh_net *net, uint8_t cnt, uint16_t interval,
 }
 
 static enum _relay_advice packet_received(void *user_data,
-				uint32_t net_key_id, uint32_t iv_index,
+				uint32_t net_key_id, uint16_t net_idx,
+				bool frnd, uint32_t iv_index,
 				const void *data, uint8_t size, int8_t rssi)
 {
 	struct mesh_net *net = user_data;
@@ -2278,16 +2287,11 @@ static enum _relay_advice packet_received(void *user_data,
 	uint8_t net_ttl, key_aid, net_segO, net_segN, net_opcode;
 	uint32_t net_seq, cache_cookie;
 	uint16_t net_src, net_dst, net_seqZero;
-	uint16_t net_idx;
 	uint8_t packet[31];
 	bool net_ctl, net_segmented, net_szmic, net_relay;
 
 	memcpy(packet + 2, data, size);
 
-	net_idx = key_id_to_net_idx(net, net_key_id);
-	if (net_idx == NET_IDX_INVALID)
-		return RELAY_NONE;
-
 	print_packet("RX: Network [clr] :", packet + 2, size);
 
 	if (!mesh_crypto_packet_parse(packet + 2, size, &net_ctl, &net_ttl,
@@ -2389,6 +2393,13 @@ static enum _relay_advice packet_received(void *user_data,
 			return RELAY_DISALLOWED;
 	}
 
+	/*
+	 * Messages that are encrypted with friendship credentials
+	 * should *always* be relayed
+	 */
+	if (frnd)
+		return RELAY_ALWAYS;
+
 	/* If relay not enable, or no more hops allowed */
 	if (!net->relay.enable || net_ttl < 0x02)
 		return RELAY_NONE;
@@ -2414,7 +2425,9 @@ static void net_rx(void *net_ptr, void *user_data)
 	uint8_t *out;
 	size_t out_size;
 	uint32_t net_key_id;
+	uint16_t net_idx;
 	int8_t rssi = 0;
+	bool frnd;
 	bool ivi_net = !!(net->iv_index & 1);
 	bool ivi_pkt = !!(data->data[0] & 0x80);
 
@@ -2438,9 +2451,21 @@ static void net_rx(void *net_ptr, void *user_data)
 		rssi = data->info->rssi;
 	}
 
-	relay_advice = packet_received(net, net_key_id, iv_index, out, out_size,
-									rssi);
+	net_idx = key_id_to_net_idx(net, net_key_id, &frnd);
+
+	if (net_idx == NET_IDX_INVALID)
+		return;
+
+	relay_advice = packet_received(net, net_key_id, net_idx, frnd,
+						iv_index, out, out_size, rssi);
 	if (relay_advice > data->relay_advice) {
+		/*
+		 * If packet was encrypted with friendship credentials,
+		 * relay it using master credentials
+		 */
+		if (frnd && !mesh_net_get_key(net, false, net_idx, &net_key_id))
+			return;
+
 		data->iv_index = iv_index;
 		data->relay_advice = relay_advice;
 		data->net_key_id = net_key_id;
-- 
2.20.1