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dns-rr: add dns_resource_record_from_json()

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This only parses a small subset of RR types for now, but we can add more
later.

Covered are the most important RR types: A, AAAA, PTR.
This commit is contained in:
Lennart Poettering
2026-02-26 15:50:26 +01:00
parent 333a9a91ef
commit 2f1bbebeb9
3 changed files with 135 additions and 4 deletions
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43
src/resolve/test-dns-rr.c
View File

@@ -7,6 +7,16 @@
#include "dns-type.h"
#include "tests.h"
static void test_to_json_from_json(DnsResourceRecord *rr) {
_cleanup_(sd_json_variant_unrefp) sd_json_variant *j = NULL;
ASSERT_OK(dns_resource_record_to_json(rr, &j));
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr2 = NULL;
ASSERT_OK(dns_resource_record_from_json(j, &rr2));
ASSERT_TRUE(dns_resource_record_equal(rr, rr2));
}
/* ================================================================
* DNS_RESOURCE_RECORD_RDATA()
* ================================================================ */
@@ -802,6 +812,8 @@ TEST(dns_resource_record_new_address_ipv4) {
ASSERT_EQ(rr->key->type, DNS_TYPE_A);
ASSERT_STREQ(dns_resource_key_name(rr->key), "www.example.com");
ASSERT_EQ(rr->a.in_addr.s_addr, addr.in.s_addr);
test_to_json_from_json(rr);
}
TEST(dns_resource_record_new_address_ipv6) {
@@ -818,6 +830,8 @@ TEST(dns_resource_record_new_address_ipv6) {
ASSERT_EQ(rr->key->type, DNS_TYPE_AAAA);
ASSERT_STREQ(dns_resource_key_name(rr->key), "www.example.com");
ASSERT_EQ(memcmp(&rr->aaaa.in6_addr, &addr.in6, sizeof(struct in6_addr)), 0);
test_to_json_from_json(rr);
}
/* ================================================================
@@ -1003,11 +1017,13 @@ TEST(dns_resource_record_equal_cname_copy) {
a = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_CNAME, "www.example.com");
ASSERT_NOT_NULL(a);
a->cname.name = strdup("example.com");
a->cname.name = ASSERT_PTR(strdup("example.com"));
b = dns_resource_record_copy(a);
ASSERT_NOT_NULL(b);
ASSERT_TRUE(dns_resource_record_equal(a, b));
test_to_json_from_json(a);
}
TEST(dns_resource_record_equal_cname_fail) {
@@ -1220,11 +1236,13 @@ TEST(dns_resource_record_equal_ptr_copy) {
a = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, "127.1.168.192.in-addr-arpa");
ASSERT_NOT_NULL(a);
a->ptr.name = strdup("example.com");
a->ptr.name = ASSERT_PTR(strdup("example.com"));
b = dns_resource_record_copy(a);
ASSERT_NOT_NULL(b);
ASSERT_TRUE(dns_resource_record_equal(a, b));
test_to_json_from_json(a);
}
TEST(dns_resource_record_equal_ptr_fail) {
@@ -2461,4 +2479,25 @@ TEST(dns_resource_record_clamp_ttl_copy) {
ASSERT_EQ(orig->ttl, 3600u);
}
static void test_from_json(const char *text, int expected) {
log_notice("Trying to parse as JSON RR: %s", text);
_cleanup_(sd_json_variant_unrefp) sd_json_variant *j = NULL;
ASSERT_OK(sd_json_parse(text, /* flags= */ 0, &j, /* reterr_line= */ NULL, /* reterr_column= */ NULL));
ASSERT_EQ(dns_resource_record_from_json(j, NULL), expected);
}
TEST(from_bad_json) {
test_from_json("{}", -EBADMSG);
test_from_json("{\"key\":{}}", -ENXIO);
test_from_json("{\"key\":{\"name\":\"foobar\",\"type\":9}}", -EOPNOTSUPP);
test_from_json("{\"key\":{\"name\":\"foobar\"}}", -ENXIO);
test_from_json("{\"key\":{\"type\":9}}", -ENXIO);
test_from_json("{\"key\":{\"name\":\"foobar\",\"type\":1}}", -ENXIO);
test_from_json("{\"key\":{\"name\":\"foobar\",\"type\":1},\"address\":[1,2,3,4]}", 0);
test_from_json("{\"key\":{\"name\":\"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\",\"type\":1},\"address\":[1,2,3,4]}", 0);
test_from_json("{\"key\":{\"name\":\"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\",\"type\":1},\"address\":[1,2,3,4]}", -EBADMSG);
test_from_json("{\"key\":{\"name\":\"a.a\",\"type\":1},\"address\":[1,2,3,4]}", 0);
test_from_json("{\"key\":{\"name\":\"a..a\",\"type\":1},\"address\":[1,2,3,4]}", -EBADMSG);
}
DEFINE_TEST_MAIN(LOG_DEBUG);

95
src/shared/dns-rr.c
View File

@@ -2308,7 +2308,6 @@ int dns_resource_record_to_json(DnsResourceRecord *rr, sd_json_variant **ret) {
int r;
assert(rr);
assert(ret);
r = dns_resource_key_to_json(rr->key, &k);
if (r < 0)
@@ -2514,11 +2513,103 @@ int dns_resource_record_to_json(DnsResourceRecord *rr, sd_json_variant **ret) {
default:
/* Can't provide broken-down format */
*ret = NULL;
if (ret)
*ret = NULL;
return 0;
}
}
int dns_resource_record_from_json(sd_json_variant *v, DnsResourceRecord **ret) {
int r;
assert(v);
sd_json_variant *k = sd_json_variant_by_key(v, "key");
if (!k)
return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG), "Resource record entry lacks key field, refusing.");
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
r = dns_resource_key_from_json(k, &key);
if (r < 0)
return r;
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
rr = dns_resource_record_new(key);
if (!rr)
return log_oom_debug();
/* Note, for now we only support the most common subset of RRs for decoding here. Please send patches for more. */
switch (key->type) {
case DNS_TYPE_PTR:
case DNS_TYPE_NS:
case DNS_TYPE_CNAME:
case DNS_TYPE_DNAME: {
_cleanup_free_ char *name = NULL;
static const struct sd_json_dispatch_field table[] = {
{ "name", SD_JSON_VARIANT_STRING, sd_json_dispatch_string, 0, SD_JSON_MANDATORY },
{ "key", SD_JSON_VARIANT_OBJECT, NULL, 0, SD_JSON_MANDATORY },
{}
};
r = sd_json_dispatch(v, table, /* flags= */ 0, &name);
if (r < 0)
return r;
r = dns_name_is_valid(name);
if (r < 0)
return r;
if (r == 0)
return -EBADMSG;
rr->ptr.name = TAKE_PTR(name);
break;
}
case DNS_TYPE_A: {
struct in_addr addr = {};
static const struct sd_json_dispatch_field table[] = {
{ "address", _SD_JSON_VARIANT_TYPE_INVALID, json_dispatch_in_addr, 0, SD_JSON_MANDATORY },
{ "key", SD_JSON_VARIANT_OBJECT, NULL, 0, SD_JSON_MANDATORY },
{}
};
r = sd_json_dispatch(v, table, /* flags= */ 0, &addr);
if (r < 0)
return r;
rr->a.in_addr = addr;
break;
}
case DNS_TYPE_AAAA: {
struct in6_addr addr = {};
static const struct sd_json_dispatch_field table[] = {
{ "address", _SD_JSON_VARIANT_TYPE_INVALID, json_dispatch_in6_addr, 0, SD_JSON_MANDATORY },
{ "key", SD_JSON_VARIANT_OBJECT, NULL, 0, SD_JSON_MANDATORY },
{}
};
r = sd_json_dispatch(v, table, /* flags= */ 0, &addr);
if (r < 0)
return r;
rr->aaaa.in6_addr = addr;
break;
}
default:
return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Decoding DNS type %s is currently not supported.", dns_type_to_string(key->type));
}
if (ret)
*ret = TAKE_PTR(rr);
return 0;
}
static const char* const dnssec_algorithm_table[_DNSSEC_ALGORITHM_MAX_DEFINED] = {
/* Mnemonics as listed on https://www.iana.org/assignments/dns-sec-alg-numbers/dns-sec-alg-numbers.xhtml */
[DNSSEC_ALGORITHM_RSAMD5] = "RSAMD5",

1
src/shared/dns-rr.h
View File

@@ -419,6 +419,7 @@ int dns_resource_record_new_from_raw(DnsResourceRecord **ret, const void *data,
int dns_resource_key_to_json(DnsResourceKey *key, sd_json_variant **ret);
int dns_resource_key_from_json(sd_json_variant *v, DnsResourceKey **ret);
int dns_resource_record_to_json(DnsResourceRecord *rr, sd_json_variant **ret);
int dns_resource_record_from_json(sd_json_variant *v, DnsResourceRecord **ret);
void dns_resource_key_hash_func(const DnsResourceKey *k, struct siphash *state);
int dns_resource_key_compare_func(const DnsResourceKey *x, const DnsResourceKey *y);