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resolve: change DNS_PACKET_UNICAST_SIZE_LARGE_MAX to 1232 (#27171)

The old common default was 4096, until 2020 on which all DNS servers (verified
on BIND9, NSD, Unbound, dnsmasq) switched to 1232 as an agreed max size [1].

[1] https://www.dnsflagday.net/2020/#message-size-considerations

(cherry picked from commit e144a26306dbe07fe37f294301421a938b781247)
(cherry picked from commit b2e1dabbeb020e06ecaecedc05187b60f78669c8)
(cherry picked from commit 9b832c44577f57fdc1fce1f66774c1c33e7f6d4d)
This commit is contained in:
Cristian Rodríguez 2023-04-07 03:52:52 -04:00 committed by Luca Boccassi
parent 2866dee297
commit 7fb9c442b7

View File

@ -55,8 +55,8 @@ assert_cc(sizeof(DnsPacketHeader) == 12);
/* RFC 1035 say 512 is the maximum, for classic unicast DNS */
#define DNS_PACKET_UNICAST_SIZE_MAX 512u
/* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */
#define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096u
/* With EDNS0 we can use larger packets, default to 1232, which is what is commonly used */
#define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 1232u
struct DnsPacket {
unsigned n_ref;