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add a node chain traversal mechanism

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dns_qp_findname_ancestor() now takes an optional 'chain' parameter;
if set, the dns_qpchain object it points to will be updated with an
array of pointers to the populated nodes between the tree root and the
requested name. the number of nodes in the chain can then be accessed
using dns_qpchain_length() and the individual nodes using
dns_qpchain_node().
This commit is contained in:
Evan Hunt
2023-09-08 17:44:53 -07:00
parent 29cf7dceb7
commit 7f766ba7c4
10 changed files with 299 additions and 54 deletions
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61
lib/dns/include/dns/qp.h
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@@ -86,6 +86,7 @@
#include <isc/attributes.h>
#include <dns/name.h>
#include <dns/types.h>
/*%
@@ -182,8 +183,9 @@ typedef union dns_qpreadable {
typedef uint8_t dns_qpkey_t[DNS_QP_MAXKEY];
/*%
* A trie iterator describes a path through the trie from the root to
* a leaf node, for use with `dns_qpiter_init()` and `dns_qpiter_next()`.
* A QP iterator traverses a trie starting with the root and passing
* though each leaf node in lexicographic order; it is used with
* `dns_qpiter_init()` and `dns_qpiter_next()`.
*/
typedef struct dns_qpiter {
unsigned int magic;
@@ -195,6 +197,22 @@ typedef struct dns_qpiter {
} stack[DNS_QP_MAXKEY];
} dns_qpiter_t;
/*%
* A QP chain holds references to each populated node between
* the root and a given leaf. It is set while running
* `dns_qp_findname_ancestor()`, and can optionally be passed
* back to the caller so that individual nodes can be accessed.
*/
typedef struct dns_qpchain {
unsigned int magic;
dns_qpreader_t *qp;
uint8_t len;
struct {
void *node;
size_t offset;
} chain[DNS_NAME_MAXLABELS];
} dns_qpchain_t;
/*%
* These leaf methods allow the qp-trie code to call back to the code
* responsible for the leaf values that are stored in the trie. The
@@ -481,7 +499,7 @@ dns_qp_getname(dns_qpreadable_t qpr, const dns_name_t *name, void **pval_r,
isc_result_t
dns_qp_findname_ancestor(dns_qpreadable_t qpr, const dns_name_t *name,
dns_qpfind_t options, dns_name_t *foundname,
void **pval_r, uint32_t *ival_r);
dns_qpchain_t *chain, void **pval_r, uint32_t *ival_r);
/*%<
* Find a leaf in a qp-trie that is an ancestor domain of, or equal to, the
* given DNS name.
@@ -491,6 +509,10 @@ dns_qp_findname_ancestor(dns_qpreadable_t qpr, const dns_name_t *name,
*
* If 'foundname' is not NULL, it is updated to contain the name found.
*
* If 'chain' is not NULL, it is updated to contain a QP chain with
* references to the populated nodes in the tree between the root and
* the name found.
*
* The leaf values are assigned to whichever of `*pval_r` and `*ival_r`
* are not null, unless the return value is ISC_R_NOTFOUND.
*
@@ -600,6 +622,39 @@ dns_qpiter_next(dns_qpiter_t *qpi, void **pval_r, uint32_t *ival_r);
* \li ISC_R_NOMORE otherwise
*/
void
dns_qpchain_init(dns_qpreadable_t qpr, dns_qpchain_t *chain);
/*%<
* Initialize a QP chain.
*
* Requires:
* \li `qpr` is a pointer to a valid qp-trie
* \li `chain` is not NULL.
*/
unsigned int
dns_qpchain_length(dns_qpchain_t *chain);
/*%<
* Returns the length of a QP chain.
*
* Requires:
* \li `chain` is a pointer to an initialized QP chain object.
*/
void
dns_qpchain_node(dns_qpchain_t *chain, unsigned int level, dns_name_t *name,
void **pval_r, uint32_t *ival_r);
/*%<
* Sets 'name' to the name of the leaf referenced at `chain->stack[level]`.
*
* The leaf values are assigned to whichever of `*pval_r` and `*ival_r`
* are not null.
*
* Requires:
* \li `chain` is a pointer to an initialized QP chain object.
* \li `level` is less than `chain->len`.
*/
/***********************************************************************
*
* functions - transactions