src/resolve/resolved-dns-answer.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once

typedef struct DnsAnswer DnsAnswer;
typedef struct DnsAnswerItem DnsAnswerItem;

#include "macro.h"
#include "resolved-dns-rr.h"
#include "set.h"

/* A simple array of resource records. We keep track of the originating ifindex for each RR where that makes
 * sense, so that we can qualify A and AAAA RRs referring to a local link with the right ifindex.
 *
 * Note that we usually encode the empty DnsAnswer object as a simple NULL. */

typedef enum DnsAnswerFlags {
        DNS_ANSWER_AUTHENTICATED      = 1 << 0, /* Item has been authenticated */
        DNS_ANSWER_CACHEABLE          = 1 << 1, /* Item is subject to caching */
        DNS_ANSWER_SHARED_OWNER       = 1 << 2, /* For mDNS: RRset may be owner by multiple peers */
        DNS_ANSWER_CACHE_FLUSH        = 1 << 3, /* For mDNS: sets cache-flush bit in the rrclass of response records */
        DNS_ANSWER_GOODBYE            = 1 << 4, /* For mDNS: item is subject to disappear */
        DNS_ANSWER_SECTION_ANSWER     = 1 << 5, /* When parsing: RR originates from answer section */
        DNS_ANSWER_SECTION_AUTHORITY  = 1 << 6, /* When parsing: RR originates from authority section */
        DNS_ANSWER_SECTION_ADDITIONAL = 1 << 7, /* When parsing: RR originates from additional section */

        DNS_ANSWER_MASK_SECTIONS      = DNS_ANSWER_SECTION_ANSWER|
                                        DNS_ANSWER_SECTION_AUTHORITY|
                                        DNS_ANSWER_SECTION_ADDITIONAL,
} DnsAnswerFlags;

struct DnsAnswerItem {
        DnsResourceRecord *rr;
        DnsResourceRecord *rrsig; /* Optionally, also store RRSIG RR that successfully validates this item */
        int ifindex;
        DnsAnswerFlags flags;
};

struct DnsAnswer {
        unsigned n_ref;
        Set *set_items; /* Used by dns_answer_add() for optimization. */
        size_t n_rrs, n_allocated;
        DnsAnswerItem items[0];
};

DnsAnswer *dns_answer_new(size_t n);
DnsAnswer *dns_answer_ref(DnsAnswer *a);
DnsAnswer *dns_answer_unref(DnsAnswer *a);

int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr, int ifindex, DnsAnswerFlags flags, DnsResourceRecord *rrsig);
int dns_answer_add_extend(DnsAnswer **a, DnsResourceRecord *rr, int ifindex, DnsAnswerFlags flags, DnsResourceRecord *rrsig);
int dns_answer_add_soa(DnsAnswer *a, const char *name, uint32_t ttl, int ifindex);

int dns_answer_match_key(DnsAnswer *a, const DnsResourceKey *key, DnsAnswerFlags *ret_flags);
bool dns_answer_contains_nsec_or_nsec3(DnsAnswer *a);
int dns_answer_contains_zone_nsec3(DnsAnswer *answer, const char *zone);
bool dns_answer_contains(DnsAnswer *answer, DnsResourceRecord *rr);

int dns_answer_find_soa(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *ret_flags);
int dns_answer_find_cname_or_dname(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *ret_flags);

int dns_answer_merge(DnsAnswer *a, DnsAnswer *b, DnsAnswer **ret);
int dns_answer_extend(DnsAnswer **a, DnsAnswer *b);

void dns_answer_order_by_scope(DnsAnswer *a, bool prefer_link_local);

int dns_answer_reserve(DnsAnswer **a, size_t n_free);
int dns_answer_reserve_or_clone(DnsAnswer **a, size_t n_free);

int dns_answer_remove_by_key(DnsAnswer **a, const DnsResourceKey *key);
int dns_answer_remove_by_rr(DnsAnswer **a, DnsResourceRecord *rr);
int dns_answer_remove_by_answer_keys(DnsAnswer **a, DnsAnswer *b);

int dns_answer_copy_by_key(DnsAnswer **a, DnsAnswer *source, const DnsResourceKey *key, DnsAnswerFlags or_flags, DnsResourceRecord *rrsig);
int dns_answer_move_by_key(DnsAnswer **to, DnsAnswer **from, const DnsResourceKey *key, DnsAnswerFlags or_flags, DnsResourceRecord *rrsig);

int dns_answer_has_dname_for_cname(DnsAnswer *a, DnsResourceRecord *cname);

static inline size_t dns_answer_size(DnsAnswer *a) {
        return a ? a->n_rrs : 0;
}

static inline bool dns_answer_isempty(DnsAnswer *a) {
        return dns_answer_size(a) <= 0;
}

void dns_answer_dump(DnsAnswer *answer, FILE *f);

void dns_answer_randomize(DnsAnswer *a);

uint32_t dns_answer_min_ttl(DnsAnswer *a);

DEFINE_TRIVIAL_CLEANUP_FUNC(DnsAnswer*, dns_answer_unref);

#define _DNS_ANSWER_FOREACH(q, kk, a)                                   \
        for (size_t UNIQ_T(i, q) = ({                                   \
                        (kk) = dns_answer_isempty(a) ? NULL : (a)->items[0].rr; \
                        0;                                              \
                });                                                     \
             UNIQ_T(i, q) < dns_answer_size(a);                         \
             UNIQ_T(i, q)++,                                            \
                     (kk) = UNIQ_T(i, q) < dns_answer_size(a) ? (a)->items[UNIQ_T(i, q)].rr : NULL)

#define DNS_ANSWER_FOREACH(kk, a) _DNS_ANSWER_FOREACH(UNIQ, kk, a)

#define _DNS_ANSWER_FOREACH_IFINDEX(q, kk, ifi, a)                      \
        for (size_t UNIQ_T(i, q) = ({                                   \
                                (kk) = dns_answer_isempty(a) ? NULL : (a)->items[0].rr; \
                                (ifi) = dns_answer_isempty(a) ? 0 : (a)->items[0].ifindex; \
                                0;                                      \
                        });                                             \
             UNIQ_T(i, q) < dns_answer_size(a);                         \
             UNIQ_T(i, q)++,                                            \
                     (kk) = UNIQ_T(i, q) < dns_answer_size(a) ? (a)->items[UNIQ_T(i, q)].rr : NULL, \
                     (ifi) = UNIQ_T(i, q) < dns_answer_size(a) ? (a)->items[UNIQ_T(i, q)].ifindex : 0)

#define DNS_ANSWER_FOREACH_IFINDEX(kk, ifindex, a) _DNS_ANSWER_FOREACH_IFINDEX(UNIQ, kk, ifindex, a)

#define _DNS_ANSWER_FOREACH_FLAGS(q, kk, fl, a)                         \
        for (size_t UNIQ_T(i, q) = ({                                   \
                                (kk) = dns_answer_isempty(a) ? NULL : (a)->items[0].rr; \
                                (fl) = dns_answer_isempty(a) ? 0 : (a)->items[0].flags; \
                                0;                                      \
                        });                                             \
             UNIQ_T(i, q) < dns_answer_size(a);                         \
             UNIQ_T(i, q)++,                                            \
                     (kk) = UNIQ_T(i, q) < dns_answer_size(a) ? (a)->items[UNIQ_T(i, q)].rr : NULL, \
                     (fl) = UNIQ_T(i, q) < dns_answer_size(a) ? (a)->items[UNIQ_T(i, q)].flags : 0)

#define DNS_ANSWER_FOREACH_FLAGS(kk, flags, a) _DNS_ANSWER_FOREACH_FLAGS(UNIQ, kk, flags, a)

#define _DNS_ANSWER_FOREACH_ITEM(q, item, a)                            \
        for (size_t UNIQ_T(i, q) = ({                                   \
                                (item) = dns_answer_isempty(a) ? NULL : (a)->items; \
                                0;                                      \
                        });                                             \
             UNIQ_T(i, q) < dns_answer_size(a);                         \
             UNIQ_T(i, q)++,                                            \
                     (item) = (UNIQ_T(i, q) < dns_answer_size(a)) ? (a)->items + UNIQ_T(i, q) : NULL)

#define DNS_ANSWER_FOREACH_ITEM(item, a) _DNS_ANSWER_FOREACH_ITEM(UNIQ, item, a)