resolve: Try to remove the ambiguity about the mtu parameter of dns_packet_new (#6285)

Actually the caller of dns_packet_new() pass 0 or the data size of the UDP message.
So try to reflect that, so rename the `mtu` parameter to `min_alloc_dsize`.

In fact `mtu` is the size of the whole UDP message, including the UDP header,
and here we just need to pass the size of data (without header). This was confusing.

Also add a check on the requested allocated size, since some caller do not check what is really allocated.
Indeed the function do not allocate more than DNS_PACKET_SIZE_MAX whatever the value of the `mtu` parameter.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index 5dff272fd9..a65d6d38cf 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -183,8 +183,8 @@ static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
                 (unsigned) DNS_PACKET_ARCOUNT(p);
 }
 
-int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
-int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled);
+int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t min_alloc_dsize);
+int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t min_alloc_dsize, bool dnssec_checking_disabled);
 
 void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated);