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DNS: Base32-encode NSEC3 Next Hashed Owner Name 

As the owner name of each NSEC3 record is Base32-encoded, the Next
Hashed Owner Name field in those records should also be displayed in
Base32-encoded form.  This enables the user to quickly tell what span of
hashed owner names is covered by a given NSEC3 record.
This commit is contained in:
Michał Kępień 2022-01-25 20:58:16 +01:00 committed by A Wireshark GitLab Utility
parent f7a882d3eb
commit d408ad5ba8
1 changed files with 21 additions and 3 deletions
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24
epan/dissectors/packet-dns.c
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@ -3344,9 +3344,14 @@ dissect_dns_answer(tvbuff_t *tvb, int offsetx, int dns_data_offset,
{
int rr_len, initial_offset = cur_offset;
guint8 salt_len, hash_len;
proto_item *flags_item;
proto_item *flags_item, *hash_item;
proto_tree *flags_tree;
/* Base 32 Encoding with Extended Hex Alphabet (see RFC 4648 section 7) */
const char *base32hex = "0123456789abcdefghijklmnopqrstuv";
char *hash_value_base32hex;
int group, in_offset, out_offset;
proto_tree_add_item(rr_tree, hf_dns_nsec3_algo, tvb, cur_offset, 1, ENC_BIG_ENDIAN);
cur_offset += 1;
@ -3369,7 +3374,20 @@ dissect_dns_answer(tvbuff_t *tvb, int offsetx, int dns_data_offset,
hash_len = tvb_get_guint8(tvb, cur_offset);
cur_offset += 1;
proto_tree_add_item(rr_tree, hf_dns_nsec3_hash_value, tvb, cur_offset, hash_len, ENC_NA);
/*
* The code below is optimized for simplicity as trailing padding
* characters ("=") are not used in the NSEC3 specification (see RFC 5155
* section 1.3).
*/
hash_value_base32hex = (char *)wmem_alloc0(wmem_packet_scope(), hash_len * 2);
for (in_offset = 0, out_offset = 0;
in_offset / 8 < hash_len;
in_offset += 5, out_offset += 1) {
group = tvb_get_bits8(tvb, cur_offset * 8 + in_offset, 5);
hash_value_base32hex[out_offset] = base32hex[group];
}
hash_item = proto_tree_add_string(rr_tree, hf_dns_nsec3_hash_value, tvb, cur_offset, hash_len, hash_value_base32hex);
proto_item_set_generated(hash_item);
cur_offset += hash_len;
rr_len = data_len - (cur_offset - initial_offset);
@ -5915,7 +5933,7 @@ proto_register_dns(void)
{ &hf_dns_nsec3_hash_value,
{ "Next hashed owner", "dns.nsec3.hash_value",
FT_BYTES, BASE_NONE, NULL, 0,
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }},
{ &hf_dns_tlsa_certificate_usage,