This patch implements:
1. A dns server that handles .et.net. zone in local and forward all other queries to system dns server.
2. A dns server instance which is a singleton in one machine, using one specific tcp port to be exclusive with each other. this instance is responsible for config system dns and run the dns server to handle dns queries.
3. A dns client instance that all easytier instance will run one, this instance will try to connect to dns server instance, and update the dns record in the dns server instance.
this pr only implements the system config for windows. linux & mac will do later.
* fix peer rpc stop working because of mpsc tunnel close unexpectedly
* fix gui:
1. allow set network prefix for virtual ipv4
2. fix android crash
3. fix subnet proxy cannot be set on android
this patch optimize the udp hole punch logic:
1. allow start punch hole before stun test complete.
2. add lock to symmetric punch, avoid conflict between concurrent hole punching task.
3. support punching hole for predictable nat4-nat4.
4. make backoff of retry reasonable
This patch removes Tarpc & Tonic GRPC and implements a customized rpc framework, which can be used by peer rpc and cli interface.
web config server can also use this rpc framework.
moreover, rewrite the public server logic, use ospf route to implement public server based networking. this make public server mesh possible.
Sijie.Sun