sing-box UDP DNS type create mass of UDP sockets that are not released

[ZeroClover]

Operating system

Linux

System version

Debian 13 trixie

Installation type

Original sing-box Command Line

If you are using a graphical client, please provide the version of the client.

No response

Version

sing-box version 1.12.0-alpha.2

Environment: go1.23.5 linux/amd64
Tags: with_gvisor,with_quic,with_dhcp,with_wireguard,with_ech,with_utls,with_reality_server,with_acme,with_clash_api
Revision: 460c5236718b3bab9baf63f32333bae41a6f135e
CGO: disabled

Description

When using UDP DNS server type, sing-box creates numerous UDP sockets and fails to release them, leading to a gradual increase in the number of sockets as sing-box runs until the 5-tuple is exhausted.

This phenomenon does not occur in version 1.11.0.

lsof -i udp:53
sing-box 105611 root 8200u  IPv4 1804714      0t0  UDP localhost:35419->localhost:domain 
sing-box 105611 root 8201u  IPv4 1806459      0t0  UDP localhost:59827->localhost:domain 
sing-box 105611 root 8202u  IPv4 1804719      0t0  UDP localhost:57271->localhost:domain 
sing-box 105611 root 8203u  IPv4 1804720      0t0  UDP localhost:47106->localhost:domain 
sing-box 105611 root 8204u  IPv4 1807387      0t0  UDP localhost:40489->localhost:domain 
sing-box 105611 root 8205u  IPv4 1804878      0t0  UDP localhost:49876->localhost:domain 
sing-box 105611 root 8206u  IPv4 1807388      0t0  UDP localhost:60220->localhost:domain 
sing-box 105611 root 8207u  IPv4 1807697      0t0  UDP localhost:33344->localhost:domain 
sing-box 105611 root 8208u  IPv4 1808948      0t0  UDP localhost:37605->localhost:domain 
sing-box 105611 root 8209u  IPv4 1804734      0t0  UDP localhost:60493->localhost:domain 
sing-box 105611 root 8210u  IPv4 1805923      0t0  UDP localhost:54634->localhost:domain 
sing-box 105611 root 8211u  IPv4 1806172      0t0  UDP localhost:37663->localhost:domain 
sing-box 105611 root 8212u  IPv4 1806683      0t0  UDP localhost:51929->localhost:domain 
sing-box 105611 root 8213u  IPv4 1805959      0t0  UDP localhost:50436->localhost:domain 
sing-box 105611 root 8214u  IPv4 1806511      0t0  UDP localhost:43363->localhost:domain 

Reproduction

{
  "log":{
    "level":"info"
  },
  "dns":{
    "servers": [
      {
        "tag": "dnsproxy",
        "type": "udp",
        "server": "127.0.0.1"
      }
    ]
  },
  "ntp":{
    "enabled":true,
    "server":"time.cloudflare.com",
    "server_port":123,
    "interval":"30m"
  },
  "inbounds":[
    {
      "tag":"ss2022",
      "type":"shadowsocks",
      "listen":"::",
      "listen_port":2022,
      "tcp_multi_path":true,
      "udp_fragment":true,
      "udp_timeout":"5m",
      "method":"2022-blake3-aes-256-gcm",
      "password": "xxxxxxxxxx",
      "users": [
        {
          "name": "zero",
          "password": "xxxxxxxxxx"
        }
      ]
    }
  ],
  "outbounds":[
    {
      "type":"direct",
      "tag": "direct",
      "domain_resolver": "dnsproxy",
      "domain_strategy": "prefer_ipv4"
    }
  ],
  "route": {
      "default_domain_resolver": {
        "server": "dnsproxy"
      },
    "rules": [
      {
        "action": "resolve",
        "strategy": "prefer_ipv4"
      },
      {
        "action": "sniff",
        "timeout": "3s"
      },
      {
        "protocol": "dns",
        "action": "hijack-dns"
      },
      {
        "action": "route",
        "outbound": "direct"
      },
      {
        "action": "route-options",
        "udp_disable_domain_unmapping": true,
        "udp_timeout": "5m"
      }
    ]
  }
}

Logs

Feb 05 02:17:46 sing-box.node sing-box[105611]: INFO[90135] [2955962781 0ms] inbound/shadowsocks[ss2022]: inbound multiplex connection to login.live.com:443
Feb 05 02:17:46 sing-box.node sing-box[105611]: ERROR[90135] [2955962781 7ms] dns: lookup failed for login.live.com: exchange6: dial udp 127.0.0.1:53: connect: resource temporarily unavailable | exchange4: dial udp 127.0.0.1:53: connect: resource temporarily unavailable
Feb 05 02:17:46 sing-box.node sing-box[105611]: INFO[90135] [202936287 0ms] inbound/shadowsocks[ss2022]: inbound multiplex connection to login.live.com:443
Feb 05 02:17:46 sing-box.node sing-box[105611]: ERROR[90135] [202936287 7ms] dns: lookup failed for login.live.com: exchange6: dial udp 127.0.0.1:53: connect: resource temporarily unavailable | exchange4: dial udp 127.0.0.1:53: connect: resource temporarily unavailable
Feb 05 02:17:48 sing-box.node sing-box[105611]: INFO[90137] [1327441837 0ms] inbound/shadowsocks[ss2022]: inbound multiplex connection to login.live.com:443
Feb 05 02:17:48 sing-box.node sing-box[105611]: ERROR[90137] [1327441837 8ms] dns: lookup failed for login.live.com: exchange6: dial udp 127.0.0.1:53: connect: resource temporarily unavailable | exchange4: dial udp 127.0.0.1:53: connect: resource temporarily unavailable
Feb 05 02:17:48 sing-box.node sing-box[105611]: INFO[90137] [72354193 0ms] inbound/shadowsocks[ss2022]: inbound multiplex connection to login.live.com:443
Feb 05 02:17:48 sing-box.node sing-box[105611]: ERROR[90137] [72354193 8ms] dns: lookup failed for login.live.com: exchange6: dial udp 127.0.0.1:53: connect: resource temporarily unavailable | exchange4: dial udp 127.0.0.1:53: connect: resource temporarily unavailable
Feb 05 02:17:50 sing-box.node sing-box[105611]: INFO[90139] [232824877 0ms] inbound/shadowsocks[ss2022]: inbound connection from <REDACTED>:33106
Feb 05 02:17:50 sing-box.node sing-box[105611]: INFO[90139] [232824877 54ms] inbound/shadowsocks[ss2022]: [zero] inbound connection to init.push.apple.com:443
Feb 05 02:17:50 sing-box.node sing-box[105611]: ERROR[90139] [232824877 62ms] dns: lookup failed for init.push.apple.com: exchange6: dial udp 127.0.0.1:53: connect: resource temporarily unavailable | exchange4: dial udp 127.0.0.1:53: connect: resource temporarily unavailable
Feb 05 02:17:50 sing-box.node sing-box[105611]: INFO[90139] [44009752 0ms] inbound/shadowsocks[ss2022]: inbound connection from <REDACTED>:33108
Feb 05 02:17:50 sing-box.node sing-box[105611]: INFO[90139] [44009752 53ms] inbound/shadowsocks[ss2022]: [zero] inbound connection to init.push.apple.com:443
Feb 05 02:17:50 sing-box.node sing-box[105611]: ERROR[90139] [44009752 62ms] dns: lookup failed for init.push.apple.com: exchange6: dial udp 127.0.0.1:53: connect: resource temporarily unavailable | exchange4: dial udp 127.0.0.1:53: connect: resource temporarily unavailable

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