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socketcan: the priority/VCID field in the CAN XL header is big-endian. 

The joys of dealing with history....
This commit is contained in:
Guy Harris 2024-02-12 13:47:51 -08:00
parent a018829a36
commit 38a29e82cc
1 changed files with 11 additions and 2 deletions
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13
epan/dissectors/packet-socketcan.c
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@ -669,8 +669,13 @@ dissect_socketcan_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gu
guint32 proto_vcid;
proto_tree_add_bitmask_list(can_tree, tvb, 0, 4, canxl_prio_vcid_fields, xl_encoding);
proto_vcid = tvb_get_guint32(tvb, 0, xl_encoding);
/*
* The priority/VCID field is big-endian in LINKTYPE_CAN_SOCKETCAN
* captures, for historical reasons. It's host-endian in
* Linux cooked captures. This means we use the non-XL encoding.
*/
proto_tree_add_bitmask_list(can_tree, tvb, 0, 4, canxl_prio_vcid_fields, encoding);
proto_vcid = tvb_get_guint32(tvb, 0, encoding);
col_add_fstr(pinfo->cinfo, COL_INFO, "Priority: %u (0x%03x), VCID: %u (0x%02X)", proto_vcid & 0x7FF, proto_vcid & 0x7FF, (proto_vcid >> 16) & 0xFF, (proto_vcid >> 16) & 0xFF);
proto_item_append_text(can_tree, ", Priority: %u (0x%03x), VCID: %u (0x%02X)", proto_vcid & 0x7FF, proto_vcid & 0x7FF, (proto_vcid >> 16) & 0xFF, (proto_vcid >> 16) & 0xFF);
proto_tree_add_bitmask_list(can_tree, tvb, 4, 1, canxl_flag_fields, xl_encoding);
@ -679,6 +684,10 @@ dissect_socketcan_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gu
guint32 sdu_type;
/*
* These fields are, if multi-byte, little-endian in
* LINKTYPE_CAN_SOCKETCAN captures, so use xl_encoding.
*/
proto_tree_add_item_ret_uint(can_tree, hf_canxl_sdu_type, tvb, 5, 1, ENC_NA, &sdu_type);
proto_tree_add_item_ret_uint(can_tree, hf_canxl_len, tvb, CANXL_LEN_OFFSET, 2, xl_encoding, &can_info.len);
col_append_fstr(pinfo->cinfo, COL_INFO, ", Length: %u", can_info.len);