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socketcan: append text only after putting the value into the tree. 

Don't fetch values in advance and set the Info column and top-level
protocol item text early.  Instead, add each field to the Info column
and top-level protocol item when we add the field to the protocol tree,
so that if the frame is cut short, we dissect as much of it as we can
and put as much of it as we can into the Info column and top-level
protocol item.
This commit is contained in:
Guy Harris 2024-02-10 17:47:52 -08:00
parent 214a744bb7
commit 825f27723c
1 changed files with 20 additions and 19 deletions
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39
epan/dissectors/packet-socketcan.c
View File

@ -697,9 +697,6 @@ dissect_socketcan_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gu
proto_tree_add_item(can_tree, hf_can_padding, tvb, CANXL_DATA_OFFSET+can_info.len, -1, ENC_NA);
}
} else {
can_info.id = tvb_get_guint32(tvb, 0, encoding);
can_info.len = tvb_get_guint8(tvb, CAN_LEN_OFFSET);
if (can_packet_type == PACKET_TYPE_CAN_FD) {
can_info.fd = CAN_TYPE_CAN_FD;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CANFD");
@ -709,6 +706,16 @@ dissect_socketcan_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gu
}
col_clear(pinfo->cinfo, COL_INFO);
ti = proto_tree_add_item(tree, proto_can, tvb, 0, -1, ENC_NA);
if (can_packet_type == PACKET_TYPE_CAN_FD) {
proto_item_set_hidden(ti);
ti = proto_tree_add_item(tree, proto_canfd, tvb, 0, -1, ENC_NA);
}
can_tree = proto_item_add_subtree(ti, (can_packet_type == PACKET_TYPE_CAN_FD) ? ett_can_fd : ett_can);
/* Get the ID and flags field */
can_info.id = tvb_get_guint32(tvb, 0, encoding);
/* Error Message Frames are only encapsulated in Classic CAN frames */
if (can_packet_type == PACKET_TYPE_CAN && (can_info.id & CAN_ERR_FLAG)) {
frame_type = LINUX_CAN_ERR;
@ -725,23 +732,17 @@ dissect_socketcan_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gu
socketcan_set_source_and_destination_columns(pinfo, &can_info);
ti = proto_tree_add_item(tree, proto_can, tvb, 0, -1, ENC_NA);
if (can_packet_type == PACKET_TYPE_CAN_FD) {
proto_item_set_hidden(ti);
ti = proto_tree_add_item(tree, proto_canfd, tvb, 0, -1, ENC_NA);
}
can_tree = proto_item_add_subtree(ti, (can_packet_type == PACKET_TYPE_CAN_FD) ? ett_can_fd : ett_can);
if (can_info.id & CAN_EFF_FLAG) {
col_add_fstr(pinfo->cinfo, COL_INFO, "Ext. ID: %u (0x%08x), Length: %u", can_info.id & CAN_EFF_MASK, can_info.id & CAN_EFF_MASK, can_info.len);
proto_item_append_text(can_tree, ", Ext. ID: %u (0x%08x), Length: %u", can_info.id & CAN_EFF_MASK, can_info.id & CAN_EFF_MASK, can_info.len);
} else {
col_add_fstr(pinfo->cinfo, COL_INFO, "ID: %u (0x%03x), Length: %u", can_info.id & CAN_SFF_MASK, can_info.id & CAN_SFF_MASK, can_info.len);
proto_item_append_text(can_tree, ", ID: %u (0x%03x), Length: %u", can_info.id & CAN_SFF_MASK, can_info.id & CAN_SFF_MASK, can_info.len);
}
proto_tree_add_bitmask_list(can_tree, tvb, 0, 4, can_flags_id, encoding);
proto_tree_add_item(can_tree, hf_can_len, tvb, CAN_LEN_OFFSET, 1, ENC_NA);
if (can_info.id & CAN_EFF_FLAG) {
col_add_fstr(pinfo->cinfo, COL_INFO, "Ext. ID: %u (0x%08x)", can_info.id & CAN_EFF_MASK, can_info.id & CAN_EFF_MASK);
proto_item_append_text(can_tree, ", Ext. ID: %u (0x%08x)", can_info.id & CAN_EFF_MASK, can_info.id & CAN_EFF_MASK);
} else {
col_add_fstr(pinfo->cinfo, COL_INFO, "ID: %u (0x%03x)", can_info.id & CAN_SFF_MASK, can_info.id & CAN_SFF_MASK);
proto_item_append_text(can_tree, ", ID: %u (0x%03x)", can_info.id & CAN_SFF_MASK, can_info.id & CAN_SFF_MASK);
}
proto_tree_add_item_ret_uint(can_tree, hf_can_len, tvb, CAN_LEN_OFFSET, 1, ENC_NA, &can_info.len);
col_append_fstr(pinfo->cinfo, COL_INFO, ", Length: %u", can_info.len);
proto_item_append_text(can_tree, ", Length: %u", can_info.len);
if (frame_type == LINUX_CAN_ERR && can_info.len != CAN_ERR_DLC) {
proto_tree_add_expert(tree, pinfo, &ei_can_err_dlc_mismatch, tvb, CAN_LEN_OFFSET, 1);