ssmanager with ipv6_first option doesn't work as expected

[ntzyz]

For example, with the following configuration:

{
  "servers": [{
    "address": "::",
    "port": 34156,
    "password": "redacted",
    "method": "aes-256-gcm"
  }],
  "dns": "2001:4860:4860::8888",
  "mode": "tcp_and_udp",
  "manager_address": "127.0.0.1",
  "manager_port": 55001,
  "ipv6_first": true
}

The server will always establish connections using IPv4 unless the website is IPv6 only:

$ all_proxy=127.0.0.1:6152 curl -s cloudflare.com/cdn-cgi/trace | grep ip
ip=103.152.<redacted>.<redacted>
$ all_proxy=127.0.0.1:6152 curl -s ipv6.ip.sb
2406:4440:<redacted>::<redacted>

However, there is no such issue when using this same configuration with ssserver.

$ all_proxy=127.0.0.1:6152 curl -s cloudflare.com/cdn-cgi/trace | grep ip
ip=2406:4440:<redacted>::<redacted>

An attempt to fix the issue was made in this commit: ntzyz@f51769c. Please let me know if the patch is acceptable, I'd like to create a pull request if it's okay.

[zonyitoo]

You don't need to put ipv6_first in ManagerConfig. The only thing you should do is to add manager.set_ipv6_first(config.ipv6_first) right after:

shadowsocks-rust/crates/shadowsocks-service/src/manager/mod.rs

Lines 65 to 67 in 1c9bac4

	if let Some(resolver) = build_dns_resolver(config.dns, config.ipv6_first, &connect_opts).await {
	manager.set_dns_resolver(Arc::new(resolver));
	}

Everything should work as expected.