resolved: split out check whether reply matches our question

It's complicated enough, it deserves its own call.

(Also contains some unrelated whitespace, comment and assertion changes)

1 files changed, 24 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index b9c2dee557..399ba59749 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -2021,6 +2021,30 @@ finish:
         return r;
 }
 
+int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key) {
+        int r;
+
+        assert(p);
+        assert(key);
+
+        /* Checks if the specified packet is a reply for the specified
+         * key and the specified key is the only one in the question
+         * section. */
+
+        if (DNS_PACKET_QR(p) != 1)
+                return 0;
+
+        /* Let's unpack the packet, if that hasn't happened yet. */
+        r = dns_packet_extract(p);
+        if (r < 0)
+                return r;
+
+        if (p->question->n_keys != 1)
+                return 0;
+
+        return dns_resource_key_equal(p->question->keys[0], key);
+}
+
 static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
         [DNS_RCODE_SUCCESS] = "SUCCESS",
         [DNS_RCODE_FORMERR] = "FORMERR",