Potentially confusing displayed index of DNS rules

[john-jane-doe]

Operating system

Linux

System version

Ubuntu 20.04.6 LTS (Linux 6.5.0-1025-azure)

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 1.10.3-93966bdd

Environment: go1.23.1 linux/amd64
Tags: with_gvisor,with_dhcp,with_wireguard,with_reality_server,with_clash_api,with_quic,with_utls,with_ech
Revision: 93966bdd36fc466de7b66d5e36900e3df568e936
CGO: enabled

Description

Seems sing-box outputs a strange index (1, 3, 5, ...) for matched DNS rules:

sing-box/route/route_dns.go

Lines 59 to 68 in 93966bd

	displayRuleIndex := currentRuleIndex
	if displayRuleIndex != -1 {
	displayRuleIndex += displayRuleIndex + 1
	}
	ruleDescription := currentRule.String()
	if ruleDescription != "" {
	r.logger.DebugContext(ctx, "match[", displayRuleIndex, "] ", currentRule, " => ", currentRule.Action())
	} else {
	r.logger.DebugContext(ctx, "match[", displayRuleIndex, "] => ", currentRule.Action())
	}

This behavior is different from the displayed index when showing matched route rule:

sing-box/route/route.go

Lines 375 to 380 in 93966bd

	ruleDescription := currentRule.String()
	if ruleDescription != "" {
	r.logger.DebugContext(ctx, "match[", currentRuleIndex, "] ", currentRule, " => ", currentRule.Action())
	} else {
	r.logger.DebugContext(ctx, "match[", currentRuleIndex, "] => ", currentRule.Action())
	}

Reproduction

{
    "log": {
        "level": "debug"
    },
    "dns": {
        "servers": [
            {
                "tag": "demo-1",
                "address": "8.8.8.8"
            },
            {
                "tag": "demo-2",
                "address": "8.8.4.4"
            },
            {
                "tag": "demo-3",
                "address": "1.1.1.1"
            }
        ],
        "rules": [
            {
                "domain": [
                    "www.demo-1.com"
                ],
                "server": "demo-1"
            },
            {
                "domain": [
                    "www.demo-2.com"
                ],
                "server": "demo-2"
            },
            {
                "domain": [
                    "www.demo-3.com"
                ],
                "server": "demo-3"
            }
        ]
    },
    "inbounds": [
        {
            "type": "mixed",
            "listen": "127.0.0.1",
            "listen_port": 7890
        }
    ],
    "outbounds": [
        {
            "type": "direct",
            "tag": "direct",
        }
    ]
}

Logs

# Why 1, 3, 5 instead of 1, 2, 3 or 0, 1, 2?
DEBUG[0007] [4215554483 0ms] dns: lookup domain www.demo-1.com
DEBUG[0007] [4215554483 0ms] router: match[1] domain=www.demo-1.com => route(demo-1)
DEBUG[0007] [4215554483 0ms] router: match[1] => route(demo-1)
...
DEBUG[0012] [1933278907 0ms] dns: lookup domain www.demo-2.com
DEBUG[0012] [1933278907 0ms] router: match[3] domain=www.demo-2.com => route(demo-2)
DEBUG[0012] [1933278907 0ms] router: match[3] => route(demo-2)
...
DEBUG[0017] [3735997981 0ms] dns: lookup domain www.demo-3.com
DEBUG[0017] [3735997981 0ms] router: match[5] domain=www.demo-3.com => route(demo-3)
DEBUG[0017] [3735997981 0ms] router: match[5] => route(demo-3)
...

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Integrity requirements

• I confirm that I have read the documentation, understand the meaning of all the configuration items I wrote, and did not pile up seemingly useful options or default values.
• I confirm that I have provided the server and client configuration files and process that can be reproduced locally, instead of a complicated client configuration file that has been stripped of sensitive data.
• I confirm that I have provided the simplest configuration that can be used to reproduce the error I reported, instead of depending on remote servers, TUN, graphical interface clients, or other closed-source software.
• I confirm that I have provided the complete configuration files and logs, rather than just providing parts I think are useful out of confidence in my own intelligence.