开启fastOpen后在ipv4 only的环境下，域名解析只会返回ipv6地址，mode auto没有生效

[XxyokixX]

描述问题

当ipv4 only的机器在outbound type: direct里fastOpen的值设置为true 而且此时mode为auto时，proxy将不会正常工作

观察日志看出，发现解析出的域名是ipv6地址，并没有ipv4地址，可我只有ipv4地址，此时会提示网络不可达

2025-02-05T13:32:17+08:00       INFO    server mode
2025-02-05T13:32:17+08:00       INFO    traffic stats server up and running     {"listen": "127.0.0.1:48336"}
2025-02-05T13:32:17+08:00       INFO    server up and running   {"listen": ":45458"}
2025-02-05T13:32:17+08:00       INFO    masquerade HTTPS server up and running  {"listen": ":45458"}
2025-02-05T13:35:15+08:00       INFO    client connected        {"addr": "1.2.3.4:44095", "id": "user", "tx": 27500000}
2025-02-05T13:35:15+08:00       WARN    TCP error       {"addr": "1.2.3.4:44095", "id": "user", "reqAddr": "www.google.com:443", "error": "dial tcp6 [2404:6800:4012:7::2004]:443: connect: network is unreachable"}
2025-02-05T13:35:15+08:00       WARN    TCP error       {"addr": "1.2.3.4:44095", "id": "user", "reqAddr": "api.hy2.io:443", "error": "dial tcp6 [2606:4700:3037::ac43:d0f6]:443: connect: network is unreachable"}

如何复现

outbound配置如下就会触发这个bug

outbounds:
  - name: hihy
    type: direct
    direct:
      mode: auto
      fastOpen: true
  - name: v4_only
    type: direct
    direct:
      mode: 4
      fastOpen: true
  - name: v6_only
    type: direct
    direct:
      mode: 6
      fastOpen: true

将

  - name: hihy
    type: direct
    direct:
      mode: auto
      fastOpen: true

mode修改成46 ipv4优先，此时不会出错:

  - name: hihy
    type: direct
    direct:
      mode: 46
      fastOpen: true

或者关闭fastOpen后域名,auto将成功返回ipv4地址，也不会出错

  - name: hihy
    type: direct
    direct:
      mode: auto
      fastOpen: false

虽然由上的实验，不应该是其他配置的问题，姑且放上完整server config 以及 client config

listen: :45458
auth:
  type: password
  password: b3407d35-8359-4cc3-9d30-ed5f9fcecd44
quic:
  initStreamReceiveWindow: 10560000
  maxStreamReceiveWindow: 15840000
  initConnReceiveWindow: 26400000
  maxConnReceiveWindow: 39600000
  maxIdleTimeout: 30s
  maxIncomingStreams: 1024
  disablePathMTUDiscovery: false
bandwidth:
  up: 220mbps
  down: 55mbps
acl:
  file: /etc/hihy/acl/acl.txt
masquerade:
  type: string
  string:
    content: HelloWorld
    headers:
      content-type: text/plain
      custom-stuff: HelloWorld
    statusCode: 200
  listenHTTPS: :45458
speedTest: true
tls:
  cert: /etc/hihy/cert/helloworld.com.crt
  key: /etc/hihy/cert/helloworld.com.key
  sniGuard: strict
outbounds:
  - name: hihy
    type: direct
    direct:
      mode: auto
      fastOpen: true
  - name: v4_only
    type: direct
    direct:
      mode: 4
      fastOpen: true
  - name: v6_only
    type: direct
    direct:
      mode: 6
      fastOpen: true
trafficStats:
  listen: 127.0.0.1:48336
  secret: b3407d35-8359-4cc3-9d30-ed5f9fcecd44

server: hysteria2://[email protected]:45458,47000-48000/
tls:
  sni: helloworld.com
  insecure: true
transport:
  type: udp
  udp:
    hopInterval: 120s
quic:
  initStreamReceiveWindow: 10560000
  initConnReceiveWindow: 26400000
  maxConnReceiveWindow: 39600000
  maxStreamReceiveWindow: 15840000
  keepAlivePeriod: 60s
bandwidth:
  down: 220mbps
  up: 55mbps
fastOpen: true
lazy: true
socks5:
  listen: 127.0.0.1:20808

预期行为

希望开启fastOpen后mode: auto可以正常工作

日志

localhost:~# hihy 14
-> 14) 查看实时日志 
2025-02-05T13:32:17+08:00       INFO    server mode
2025-02-05T13:32:17+08:00       INFO    traffic stats server up and running     {"listen": "127.0.0.1:48336"}
2025-02-05T13:32:17+08:00       INFO    server up and running   {"listen": ":45458"}
2025-02-05T13:32:17+08:00       INFO    masquerade HTTPS server up and running  {"listen": ":45458"}
2025-02-05T13:35:15+08:00       INFO    client connected        {"addr": "1.2.3.4:44095", "id": "user", "tx": 27500000}
2025-02-05T13:35:15+08:00       WARN    TCP error       {"addr": "1.2.3.4:44095", "id": "user", "reqAddr": "www.google.com:443", "error": "dial tcp6 [2404:6800:4012:7::2004]:443: connect: network is unreachable"}
2025-02-05T13:35:15+08:00       WARN    TCP error       {"addr": "1.2.3.4:44095", "id": "user", "reqAddr": "api.hy2.io:443", "error": "dial tcp6 [2606:4700:3037::ac43:d0f6]:443: connect: network is unreachable"}

设备和操作系统
我在多台ipv4 only的服务器上都复现了这个bug，因此可以排除是我机器的问题，测试环境包括debian和alpine

额外信息

如果需要额外信息可以再次补充