From: Nathael Pajani <nathael.pajani@ed3l.fr>
Date: Sat, 16 Mar 2019 16:28:02 +0000 (+0100)
Subject: there is no packet ID in mqtt publish packets for QoS 0 publish
X-Git-Url: http://git.techno-innov.fr/?a=commitdiff_plain;h=93c94e151bd3ecb72fcf3fee610b569947261867;p=soft%2Flpc122x%2Fcore

there is no packet ID in mqtt publish packets for QoS 0 publish
---

diff --git a/lib/protocols/mqtt.c b/lib/protocols/mqtt.c
index d11a809..d0a62d4 100644
--- a/lib/protocols/mqtt.c
+++ b/lib/protocols/mqtt.c
@@ -253,10 +253,14 @@ int mqtt_pack_publish_packet(const struct mqtt_publish_pkt* pkt, uint8_t* buf, u
 		return -ENODATA;
 	}
 	/* Compute message size
-	 * Packet ID is 2 bytes long. There is no "message size" field in the publish packet, as the
-	 * message size can be computed by substracting the topic string size and packet id size from
-	 * the packet "remaining length" field. */
-	remaining_length = 2 + pkt->message_size;
+	 * There is no "message size" field in the publish packet, as the message size can be computed by
+	 * substracting the topic string size and packet id size from the packet "remaining length" field.
+	 */
+	remaining_length = pkt->message_size;
+	/* Packet ID is 2 bytes long. If QoS is 0, then the packet must not include a packet ID */
+	if (pkt->topic.QoS != 0) {
+		remaining_length += 2;
+	}
 	/* Topic is mandatory */
 	if (pkt->topic.name == NULL) {
 		return -EINVAL;
@@ -283,9 +287,11 @@ int mqtt_pack_publish_packet(const struct mqtt_publish_pkt* pkt, uint8_t* buf, u
 	/* Topic is mandatory */
 	len += mqtt_pack_str((buf + len), pkt->topic.name, topic_len);
 	/* Packet ID */
-	tmp_packet_id = htons(pkt->packet_id);
-	memcpy((buf + len), &tmp_packet_id, 2);
-	len += 2;
+	if (pkt->topic.QoS != 0) {
+		tmp_packet_id = htons(pkt->packet_id);
+		memcpy((buf + len), &tmp_packet_id, 2);
+		len += 2;
+	}
 	/* Add optionnal application message */
 	if (pkt->message_size != 0) {
 		memcpy((buf + len), pkt->application_message, pkt->message_size);
@@ -334,13 +340,20 @@ int mqtt_unpack_publish_packet(struct mqtt_publish_pkt* pkt, uint8_t* buf, uint3
 	topic_len = ntohs(tmp);
 	pkt->topic.name = (char*)(buf + idx + 2);
 	idx += topic_len + 2;
-	if ((idx + 2) > size) {
+	/* Does it fit in the remaining length ? */
+	tmp = idx;
+	if (pkt->topic.QoS != 0) {
+		tmp += 2;
+	}
+	if (tmp > size) {
 		return -EPROTO;
 	}
 	/* Decode packet ID */
-	idx += 2;
+	if (pkt->topic.QoS != 0) {
 		memcpy(&tmp, (buf + idx), 2);
 		pkt->packet_id = ntohs(tmp);
+		idx += 2;
+	}
 	/* Get application message */
 	pkt->message_size = size - idx;
 	if (pkt->message_size != 0) {