resolved: split out helper for allocating DnsResourceRecord object from raw data

No change in behaviour, just some refactoring.

src/resolve/resolvectl.c

@@ -395,20 +395,9 @@ static int resolve_address(sd_bus *bus, int family, const union in_addr_union *a
 
 static int output_rr_packet(const void *d, size_t l, int ifindex) {
         _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
-        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
         int r;
 
-        r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0, DNS_PACKET_SIZE_MAX);
-        if (r < 0)
-                return log_oom();
-
-        p->refuse_compression = true;
-
-        r = dns_packet_append_blob(p, d, l, NULL);
-        if (r < 0)
-                return log_oom();
-
-        r = dns_packet_read_rr(p, &rr, NULL, NULL);
+        r = dns_resource_record_new_from_raw(&rr, d, l);
         if (r < 0)
                 return log_error_errno(r, "Failed to parse RR: %m");
 

src/resolve/resolved-dns-rr.c

@@ -1832,6 +1832,23 @@ int dns_txt_item_new_empty(DnsTxtItem **ret) {
         return 0;
 }
 
+int dns_resource_record_new_from_raw(DnsResourceRecord **ret, const void *data, size_t size) {
+        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+        int r;
+
+        r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0, DNS_PACKET_SIZE_MAX);
+        if (r < 0)
+                return r;
+
+        p->refuse_compression = true;
+
+        r = dns_packet_append_blob(p, data, size, NULL);
+        if (r < 0)
+                return r;
+
+        return dns_packet_read_rr(p, ret, NULL, NULL);
+}
+
 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",

src/resolve/resolved-dns-rr.h

@@ -364,6 +364,8 @@ bool dns_txt_item_equal(DnsTxtItem *a, DnsTxtItem *b);
 DnsTxtItem *dns_txt_item_copy(DnsTxtItem *i);
 int dns_txt_item_new_empty(DnsTxtItem **ret);
 
+int dns_resource_record_new_from_raw(DnsResourceRecord **ret, const void *data, size_t size);
+
 void dns_resource_record_hash_func(const DnsResourceRecord *i, struct siphash *state);
 int dns_resource_record_compare_func(const DnsResourceRecord *x, const DnsResourceRecord *y);