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dissector/mqtt: Payload length computation 

This patch modifies how the payload length is
computed. With this patch we want to simplify
and reduce the number of operations.

Change-Id: Ie1c9a3f26c689e92fbbd57c34e4f68abd3ea7d02
Signed-off-by: Flavio Santes <flavio.santes@1byt3.com>
Reviewed-on: https://code.wireshark.org/review/24336
Petri-Dish: Stig Bjørlykke <stig@bjorlykke.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>
This commit is contained in:
Flavio Santes 2017-11-09 18:34:04 -05:00 committed by Anders Broman
parent bce5b50f73
commit d337f4c5b7
1 changed files with 8 additions and 21 deletions
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29
epan/dissectors/packet-mqtt.c
View File

@ -604,6 +604,7 @@ static int dissect_mqtt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi
gint mqtt_msg_len = 0;
guint16 mqtt_str_len;
guint16 mqtt_len_offset;
gint mqtt_payload_len;
conversation_t *conv;
mqtt_conv_t *mqtt;
@ -799,34 +800,30 @@ static int dissect_mqtt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi
mqtt_str_len = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(mqtt_tree, hf_mqtt_topic_len, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
mqtt_msg_len -= 2;
proto_tree_add_item_ret_string(mqtt_tree, hf_mqtt_topic, tvb, offset, mqtt_str_len, ENC_UTF_8|ENC_NA,
wmem_epan_scope(), &topic_str);
offset += mqtt_str_len;
mqtt_msg_len -= mqtt_str_len;
/* Message ID is included only when QoS > 0 */
if(mqtt_fixed_hdr & MQTT_MASK_QOS)
{
proto_tree_add_item(mqtt_tree, hf_mqtt_msgid, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
mqtt_msg_len -= 2;
}
if (mqtt->runtime_proto_version == MQTT_PROTO_V50)
{
guint32 mqtt_prop_offset = dissect_mqtt_properties(tvb, mqtt_tree, offset);
offset += mqtt_prop_offset;
mqtt_msg_len -= mqtt_prop_offset;
}
proto_tree_add_item(mqtt_tree, hf_mqtt_pubmsg, tvb, offset, mqtt_msg_len, ENC_UTF_8|ENC_NA);
mqtt_payload_len = tvb_reported_length(tvb) - offset;
proto_tree_add_item(mqtt_tree, hf_mqtt_pubmsg, tvb, offset, mqtt_payload_len, ENC_UTF_8|ENC_NA);
if (num_mqtt_message_decodes > 0)
{
tvbuff_t *msg_tvb = tvb_new_subset_length(tvb, offset, mqtt_msg_len);
tvbuff_t *msg_tvb = tvb_new_subset_length(tvb, offset, mqtt_payload_len);
mqtt_user_decode_message(tree, mqtt_tree, pinfo, topic_str, msg_tvb);
}
break;
@ -839,28 +836,20 @@ static int dissect_mqtt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi
proto_tree_add_item(mqtt_tree, hf_mqtt_msgid, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* Subtract the Packet Id size to compute the Payload length */
mqtt_msg_len -= 2;
if (mqtt->runtime_proto_version == MQTT_PROTO_V50)
{
guint32 mqtt_prop_offset = dissect_mqtt_properties(tvb, mqtt_tree, offset);
offset += mqtt_prop_offset;
/* Subtract the Property offset to compute the Payload length */
mqtt_msg_len -= mqtt_prop_offset;
}
while (mqtt_msg_len > 0)
while (offset < (guint32)tvb_reported_length(tvb))
{
mqtt_str_len = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(mqtt_tree, hf_mqtt_topic_len, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
mqtt_msg_len -= 2;
proto_tree_add_item(mqtt_tree, hf_mqtt_topic, tvb, offset, mqtt_str_len, ENC_UTF_8|ENC_NA);
offset += mqtt_str_len;
mqtt_msg_len -= mqtt_str_len;
if (mqtt->runtime_proto_version == MQTT_PROTO_V50)
{
@ -874,7 +863,6 @@ static int dissect_mqtt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi
}
offset += 1;
mqtt_msg_len -= 1;
}
break;
@ -885,16 +873,15 @@ static int dissect_mqtt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi
*/
proto_tree_add_item(mqtt_tree, hf_mqtt_msgid, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
for(mqtt_msg_len -= 2; mqtt_msg_len > 0;)
while (offset < (guint32)tvb_reported_length(tvb))
{
mqtt_str_len = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(mqtt_tree, hf_mqtt_topic_len, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
mqtt_msg_len -= 2;
proto_tree_add_item(mqtt_tree, hf_mqtt_topic, tvb, offset, mqtt_str_len, ENC_UTF_8|ENC_NA);
offset += mqtt_str_len;
mqtt_msg_len -= mqtt_str_len;
}
break;
@ -910,7 +897,7 @@ static int dissect_mqtt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, voi
offset += dissect_mqtt_properties(tvb, mqtt_tree, offset);
}
for(mqtt_msg_len -= 2; mqtt_msg_len > 0; mqtt_msg_len--)
while (offset < (guint32)tvb_reported_length(tvb))
{
proto_tree_add_item(mqtt_tree, hf_mqtt_suback_qos, tvb, offset, 1, ENC_BIG_ENDIAN);
offset += 1;