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Fix QP chain on partial match

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When searching for a requested name in dns_qp_lookup(), we may add
a leaf node to the QP chain, then subsequently determine that the
branch we were on was a dead end. When that happens, the chain can be
left holding a pointer to a node that is *not* an ancestor of the
requested name.

We correct for this by unwinding any chain links with an offset
value greater or equal to that of the node we found.
This commit is contained in:
Evan Hunt 2024-05-13 15:56:15 -07:00
parent 5d96f11693
commit b6815de316
1 changed files with 27 additions and 6 deletions
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33
lib/dns/qp.c
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@ -2241,6 +2241,23 @@ fix_iterator(dns_qpreader_t *qp, dns_qpiter_t *iter, dns_qpkey_t search,
}
}
/*
* When searching for a requested name in dns_qp_lookup(), we might add
* a leaf node to the chain, then subsequently determine that it was a
* dead end. When this happens, the chain can be left holding a node
* that is *not* an ancestor of the requested name. We correct for that
* here.
*/
static void
fix_chain(dns_qpchain_t *chain, size_t offset) {
while (chain->len > 0 && chain->chain[chain->len - 1].offset >= offset)
{
chain->len--;
chain->chain[chain->len].node = NULL;
chain->chain[chain->len].offset = 0;
}
}
isc_result_t
dns_qp_lookup(dns_qpreadable_t qpr, const dns_name_t *name,
dns_name_t *foundname, dns_qpiter_t *iter, dns_qpchain_t *chain,
@ -2364,16 +2381,20 @@ dns_qp_lookup(dns_qpreadable_t qpr, const dns_name_t *name,
foundlen = leaf_qpkey(qp, n, found);
offset = qpkey_compare(search, searchlen, found, foundlen);
/* the search ended with an exact or partial match */
if (offset == QPKEY_EQUAL || offset == foundlen) {
isc_result_t result = ISC_R_SUCCESS;
if (offset == foundlen) {
fix_chain(chain, offset);
result = DNS_R_PARTIALMATCH;
}
add_link(chain, n, offset);
SET_IF_NOT_NULL(pval_r, leaf_pval(n));
SET_IF_NOT_NULL(ival_r, leaf_ival(n));
maybe_set_name(qp, n, foundname);
add_link(chain, n, offset);
if (offset == QPKEY_EQUAL) {
return (ISC_R_SUCCESS);
} else {
return (DNS_R_PARTIALMATCH);
}
return (result);
}
/*