Add support for UDP proxying

[VastBlast]

Reopening #154 as it was auto closed after restructuring my fork.

This PR adds support for a proxying a UDP server through WireGuard. It can listen on IPv4 while tunneling to an IPv6 address or vice versa.

When sending, it goes through BindAddress -> Wireguard -> Target and the opposite when receiving.

For example, if you wanted to proxy Cloudflare's DNS server, an example config would be:

[Interface]
...

[Peer]
...

[UDPProxyTunnel]
BindAddress = 127.0.0.1:53

#Target = [2606:4700:4700::1111]:53
Target = 1.1.1.1:53

# If its set to 0, it will never timeout
InactivityTimeout = 30

[shihiro09]

Love the DNS use-case. cc @whyvl

Just a thought: would this enable nested wireguard tunnels with two wireproxy daemons? e.g.

outer.conf:

[Peer]
Endpoint = [outer-tunnel]:51280
PublicKey = [outer-key]

[UDPProxyTunnel]
BindAddress = 127.0.0.1:1234
Target = [inner-tunnel]:51280

inner.conf:

[Peer]
Endpoint = 127.0.0.1:1234 # inner proxy
PublicKey = [inner-key]

[VastBlast]

Love the DNS use-case. cc @whyvl

Just a thought: would this enable nested wireguard tunnels with two wireproxy daemons? e.g.

outer.conf:

[Peer]
Endpoint = [outer-tunnel]:51280
PublicKey = [outer-key]

[UDPProxyTunnel]
BindAddress = 127.0.0.1:1234
Target = [inner-tunnel]:51280

inner.conf:

[Peer]
Endpoint = 127.0.0.1:1234 # inner proxy
PublicKey = [inner-key]

Yes, it would. Might need more testing, but it should.

[penyuan]

Reopening #154 as it was auto closed after restructuring my fork.

This PR adds support for a proxying a UDP server through WireGuard. It can listen on IPv4 while tunneling to an IPv6 address or vice versa.

When sending, it goes through BindAddress -> Wireguard -> Target and the opposite when receiving.

For example, if you wanted to proxy Cloudflare's DNS server, an example config would be:

[Interface]
...

[Peer]
...

[UDPProxyTunnel]
BindAddress = 127.0.0.1:53

#Target = [2606:4700:4700::1111]:53
Target = 1.1.1.1:53

# If its set to 0, it will never timeout
InactivityTimeout = 30

@VastBlast Thanks!
Does your solution allow UDP traffic through Wireproxy's SOCKS or HTTP proxies? If so, how should it be configured in the .conf file? If not, could this capability be implemented?