Force the use of H3 (TLSv1.3) over DoH (DNS over Https)

[junzhli]

Since DoQ (DNS over Quic) is not supported at this moment, is it possible to explicitly force it to use H3 protocol in supported remote resolvers? Thanks!

[jedisct1]

Set http3 = true in the configuration file. HTTP/3 will be used if the server supports it.

[junzhli]

Seems like it can only handle Doh in HTTP/3 when there's a header src-alt containing h3 magic string.
I tried with [unique-id].dns.nextdns.io and it didn't work due to the above reason and ended up with using dot3.dns.nextdns.io/[unique-id], which hits the above condition.
Not sure if the issue is from NextDNS, anyways many thanks! @jedisct1

[zubrRB]

Having a problem with this when using AdGuard. AdguardTeam/CoreLibs#1892

[junzhli]

Hi @jedisct1 @zubrRB

I made some changes on this to force the use of httpv3 on the supplied list of hosts
It helps a lot in my case and hopefully it can be part of feature in release version!

#2846

[bcookatpcsd]

I had to enable http3 as well as the probe for http3

Now I see this in the logs:

and via tcpdump

10:51:48.128488 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 248)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 220
10:51:48.202709 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 249)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 221
10:51:48.244496 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 62)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 34
10:51:48.273566 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 62)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 34
10:51:48.278660 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 315)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 287
10:51:48.290223 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 61)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 33
10:51:48.293601 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 70)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 42
10:51:48.297853 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 61)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 33
10:51:48.326999 IP (tos 0x2,ECT(0), ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 62)
    10.120.48.253.8235 > 45.90.28.0.443: UDP, length 34

 dnscrypt-proxy -version
2.1.12