panic: V is not in context.

[rurirei]

i uses v2ray-core (commit top to #406 merged) as a Android library (code as below) and met errors as below, but do not met this if uses tree before FakeDns added. especially fakednssniffer.go appears at logs, maybe that is introduced by FakeDns commits? sorry for my not read codes of FakeDns.

[v2ray] [Warning] v2ray.com/core: V2Ray 4.34.0 started

[tun2socks] [Handle] tcp 172.19.0.1:41201 147.202.171.5:443 147.202.171.5:443

panic: V is not in context.

goroutine 31 [running]:

v2ray.com/core.MustFromContext(0x7dea651aa0, 0x4002cb94d0, 0x10)
	/home/runner/go/src/v2ray.com/core/context.go:26 +0x8c

v2ray.com/core.RequireFeatures(0x7dea651aa0, 0x4002cb94d0, 0x7dea471ce0, 0x4002638d40, 0x30, 0x7dea47c760)
	/home/runner/go/src/v2ray.com/core/v2ray.go:154 +0x28

v2ray.com/core/app/dispatcher.newFakeDNSSniffer(0x7dea651aa0, 0x4002cb94d0, 0x4002d8c070, 0x7de9f685f0, 0x7dea462280, 0x400000f460)
	/home/runner/go/src/v2ray.com/core/app/dispatcher/fakednssniffer.go:18 +0x88

v2ray.com/core/app/dispatcher.NewSniffer(0x7dea651aa0, 0x4002cb94d0, 0x400000f460)
	/home/runner/go/src/v2ray.com/core/app/dispatcher/sniffer.go:41 +0xa8

v2ray.com/core/app/dispatcher.sniffer(0x7dea651aa0, 0x4002cb94d0, 0x4002cb9590, 0x0, 0x0, 0x0, 0x0, 0x0)
	/home/runner/go/src/v2ray.com/core/app/dispatcher/default.go:252 +0xb4

v2ray.com/core/app/dispatcher.(*DefaultDispatcher).Dispatch.func1(0x400000f3c0, 0x7dea651aa0, 0x4002cb94d0, 0x400000f320, 0x2, 0x2, 0x7e00960001, 0x4000ead3c0, 0x400000f340, 0x4002cb94a0, ...)
	/home/runner/go/src/v2ray.com/core/app/dispatcher/default.go:232 +0x90

created by v2ray.com/core/app/dispatcher.(*DefaultDispatcher).Dispatch
	/home/runner/go/src/v2ray.com/core/app/dispatcher/default.go:227 +0x4f8

import (
    "context"

    vcore "v2ray.com/core"
    vnet "v2ray.com/core/common/net"
    vproxyman "v2ray.com/core/app/proxyman"
    vprotocol "v2ray.com/core/common/protocol"
    vsession "v2ray.com/core/common/session"
)

    vinbound := &vsession.Inbound{Tag: "vinbound"}

    vsniffing := &vproxyman.SniffingConfig{
        Enabled:             true,
        DestinationOverride: []string{"http", "tls"},
        MetadataOnly:        false,
    }

    vcontent := &vsession.Content{
        SniffingRequest: vsession.SniffingRequest{
            Enabled:                        vsniffing.Enabled,
            OverrideDestinationForProtocol: vsniffing.DestinationOverride,
            MetadataOnly:                   vsniffing.MetadataOnly,
        },
    }

    ctx := vsession.ContextWithID(context.Background(), vsession.NewID())
    ctx = vsession.ContextWithInbound(ctx, vinbound)
    ctx = vsession.ContextWithContent(ctx, vcontent)

    c, err := vcore.Dial(ctx, h.v, dest)

v2ray-core/context.go

Lines 14 to 29 in efb9632

	// FromContext returns an Instance from the given context, or nil if the context doesn't contain one.
	func FromContext(ctx context.Context) *Instance {
	if s, ok := ctx.Value(v2rayKey).(*Instance); ok {
	return s
	}
	return nil
	}
	// MustFromContext returns an Instance from the given context, or panics if not present.
	func MustFromContext(ctx context.Context) *Instance {
	v := FromContext(ctx)
	if v == nil {
	panic("V is not in context.")
	}
	return v
	}

[yuhan6665]

I wasn't see this issue. What's your json config?

[rurirei]

@yuhan6665

{
  "log": {
    "loglevel": "debug"
  },
  "inbounds": [  // unused inbound
    {
      "listen": "127.0.0.1",
      "port": 1080,
      "protocol": "socks",
      "settings": {
        "auth": "noauth",
        "udp": true
      },
      "sniffing": {
        "destOverride": [
          "http",
          "tls"
        ],
        "enabled": true
      }
    }
  ],
  "outbounds": [
    {
      "protocol": "shadowsocks",
      "settings": {
        "servers": [
          ...
        ]
      },
      "streamSettings": {
        "network": "tcp",
        "security": "none"
      },
      "tag": "proxy"
    }
  ],
  "routing": {
    "domainStrategy": "AsIs",
    "rules": []
  },
  "stats": {}
}

[yuhan6665]

@rurirei I tried config similar to yours but can not reproduce the issue. It is quite weird. Do you also have this issue if you turn fake dns on?

"fakedns": {
    "ipPool": "240.0.0.0/8",
    "poolSize": 65535
}
"dns": {
        "servers": [
            "fakedns"
            "8.8.8.8",
            "https://1.1.1.1/dns-query"
        ]
},
...
"sniffing": {
        "enabled": true,
        "destOverride": [
            "http",
            "tls",
            "fakedns"
        ]
},

[rurirei]

@yuhan6665 errors met as well.

[rurirei]

especially do not met this if disabled sniffing.

vsniffing := &vproxyman.SniffingConfig{
        Enabled:             false,
        DestinationOverride: []string{"http", "tls", "fakedns"},
        MetadataOnly:        false,
}

[yuhan6665]

@rurirei based on your error log, the context has some issue when init sniffer. That's why if you turn off sniffer it will be ok.
I think it is issue in your way of init the context.

    ctx := vsession.ContextWithID(context.Background(), vsession.NewID())
    ctx = vsession.ContextWithInbound(ctx, vinbound)
    ctx = vsession.ContextWithContent(ctx, vcontent)

https://github.com/2dust/AndroidLibV2rayLite

[rurirei]

@yuhan6665 that's it. i'll try v.RequireFeatures() to do not uses ctx.

v2ray-core/app/dispatcher/fakednssniffer.go

Lines 16 to 20 in 38da831

	func newFakeDNSSniffer(ctx context.Context) (protocolSnifferWithMetadata, error) {
	var fakeDNSEngine dns.FakeDNSEngine
	err := core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) {
	fakeDNSEngine = fdns
	})

[rurirei]

seems gently fixed by.

v2ray-core/functions.go

Line 19 in 38da831

ctx = context.WithValue(v.ctx, v2rayKey, v)

[rurirei]

seems ok.

[v2ray] [Debug] v2ray.com/core/app/dns: domain github.com will use DNS in order: [FakeDNS]
[v2ray] [Info] [3492521930] v2ray.com/core/app/dispatcher: fake dns got domain: github.com for ip: 198.18.0.2
[v2ray] [Info] [3492521930] v2ray.com/core/app/dispatcher: sniffed domain: github.com
[v2ray] [Info] [3492521930] v2ray.com/core/app/dispatcher: taking detour [proxy] for [tcp:github.com:443]

[simo8102]

Add to config

"sniffing": {
"enabled": true,
"destOverride": [
"http",
"tls",
"fakedns"
]
},