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BER: fix ber.error.bits_unknown display 

Before the changes done in v3.1.0rc0-431-gc2ac157ac0 and
v3.1.0rc0-458-g37b91eedd6 the expert info was only displayed
if at least 1 unknown bit was set to 1. Restore this behavior.

Bug: 16301
Change-Id: I3bea0992d6727154ef07d40ac18a7b012d3c1da4
Reviewed-on: https://code.wireshark.org/review/35612
Petri-Dish: Pascal Quantin <pascal@wireshark.org>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Pascal Quantin <pascal@wireshark.org>
This commit is contained in:
Pascal Quantin 2019-12-31 00:09:39 +01:00
parent 4f105e1f24
commit 11aef7c19b
1 changed files with 19 additions and 10 deletions
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29
epan/dissectors/packet-ber.c
View File

@ -4035,6 +4035,7 @@ dissect_ber_constrained_bitstring(gboolean implicit_tag, asn1_ctx_t *actx, proto
item = proto_tree_add_item(parent_tree, hf_id, tvb, offset, len, ENC_NA);
actx->created_item = item;
if (named_bits) {
guint8 *bitstring = (guint8 *)tvb_memdup(wmem_packet_scope(), tvb, offset, len);
const int named_bits_bytelen = (num_named_bits + 7) / 8;
if (show_internal_ber_fields) {
guint zero_bits_omitted = 0;
@ -4047,13 +4048,6 @@ dissect_ber_constrained_bitstring(gboolean implicit_tag, asn1_ctx_t *actx, proto
tree = proto_item_add_subtree(item, ett_id);
}
for (int i = 0; i < named_bits_bytelen; i++) {
// If less data is available than the number of named bits, then
// the trailing (right) bits are assumed to be 0.
guint64 value = 0;
if (i < len) {
value = tvb_get_guint8(tvb, offset + i);
}
// Process 8 bits at a time instead of 64, each field masks a
// single byte.
const int bit_offset = 8 * i;
@ -4065,6 +4059,18 @@ dissect_ber_constrained_bitstring(gboolean implicit_tag, asn1_ctx_t *actx, proto
section_named_bits = (const int** )flags;
}
// If less data is available than the number of named bits, then
// the trailing (right) bits are assumed to be 0.
guint64 value = 0;
if (i < len) {
value = bitstring[i];
if (num_named_bits - bit_offset > 7) {
bitstring[i] = 0;
} else {
bitstring[i] &= 0xff >> (num_named_bits - bit_offset);
}
}
// TODO should non-zero pad bits be masked from the value?
// When trailing zeroes are not present in the data, mark the
// last byte for the lack of a better alternative.
@ -4072,9 +4078,12 @@ dissect_ber_constrained_bitstring(gboolean implicit_tag, asn1_ctx_t *actx, proto
}
// If more data is available than the number of named bits, then
// either the spec was updated or the packet is malformed.
if (named_bits_bytelen < len) {
expert_add_info_format(actx->pinfo, item, &ei_ber_bits_unknown, "Unknown bit(s): 0x%s",
tvb_bytes_to_str(wmem_packet_scope(), tvb, offset + named_bits_bytelen, len - named_bits_bytelen));
for (int i = 0; i < len; i++) {
if (bitstring[i]) {
expert_add_info_format(actx->pinfo, item, &ei_ber_bits_unknown, "Unknown bit(s): 0x%s",
bytes_to_str(wmem_packet_scope(), bitstring, len));
break;
}
}
}
}