[New feature] The bootstrap resolver feature could support DNS-over-TCP and to set the port arbitrarily

[junkurihara]

          The bootstrap resolver feature could support DNS-over-TCP and to set the port arbitrarily. This would be useful in firewalled environments, when the UDP or ports other than 80/443 are blocked.

Originally posted by @przemyslaw0 in #43 (comment)

[przemyslaw0]

OpenDNS has some resolvers that accepts connections on port 443 and works well with TCP:

208.67.222.222:443
208.67.220.220:443
[2620:119:35::35]:443
[2620:119:53::53]:443

Really good for a firewalled environment. My mobile phone provider blocks UDP ports other than 53 (for avoiding Torrent), DNSCrypt with anonymized relays doesn't work well here when I use USB Thetering, but doh-auth-proxy does.

[junkurihara]

Now the develop branch just supported TCP bootstrap DNS resolver with an arbitrary port. To explicitly specify the protocol and port, we need to set the resolver as tcp://1.1.1.1:53 in toml file. But existing format without protocol and port, e.g., 1.1.1.1, still works as an alias of udp://1.1.1.1:53.

I will ship this in the next patch release (not a breaking change due to the alias).

[przemyslaw0]

@junkurihara

Thanks a lot, I will test later.