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SparkplugB: Fix handling of malformed message 

Make the dissector more defensive when handling a message with
a malformed topic string

Fixes #17566
This commit is contained in:
Graham Bloice 2021-09-03 13:04:48 +01:00
parent 738670df7e
commit 436eab0d77
1 changed files with 26 additions and 16 deletions
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42
epan/dissectors/packet-sparkplug.c
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@ -58,6 +58,7 @@ dissect_sparkplugb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *da
gchar **topic_elements, **current_element;
char *topic = (char *)data;
/* Confirm the expected topic data is present */
if (topic == NULL)
return FALSE;
@ -75,7 +76,7 @@ dissect_sparkplugb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *da
/* Adjust the info column */
col_clear(pinfo->cinfo, COL_INFO);
col_set_str(pinfo->cinfo, COL_INFO, "SparkplugB");
col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, "SparkplugB");
/* create display subtree for the protocol */
ti = proto_tree_add_item(tree, proto_sparkplugb, tvb, 0, -1, ENC_NA);
@ -90,10 +91,13 @@ dissect_sparkplugb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *da
proto_item_set_generated(ti);
current_element += 1;
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_groupid, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
if (!current_element[0]) {
expert_add_info(pinfo, ti, &ei_sparkplugb_missing_groupid);
if (current_element[0]) {
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_groupid, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
}
else {
expert_add_info(pinfo, namespace_tree, &ei_sparkplugb_missing_groupid);
return FALSE;
}
/* Adjust the info colum text with the message type */
@ -101,25 +105,31 @@ dissect_sparkplugb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *da
if (current_element[0]) {
col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, current_element[0]);
col_set_fence(pinfo->cinfo, COL_INFO);
}
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_messagetype, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
if (!current_element[0]) {
expert_add_info(pinfo, ti, &ei_sparkplugb_missing_messagetype);
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_messagetype, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
}
else {
expert_add_info(pinfo, namespace_tree, &ei_sparkplugb_missing_messagetype);
return FALSE;
}
current_element += 1;
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_edgenodeid, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
if (!current_element[0]) {
expert_add_info(pinfo, ti, &ei_sparkplugb_missing_edgenodeid);
if (current_element[0]) {
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_edgenodeid, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
}
else {
expert_add_info(pinfo, namespace_tree, &ei_sparkplugb_missing_edgenodeid);
return FALSE;
}
/* Device ID is optional */
current_element += 1;
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_deviceid, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
if (current_element[0]) {
ti = proto_tree_add_string(namespace_tree, hf_sparkplugb_deviceid, tvb, 0, 0, current_element[0]);
proto_item_set_generated(ti);
}
g_strfreev(topic_elements);