Feat: [app/dns] Support per-client configuration #1977

Vigilans · 2022-09-12T14:33:42Z

This PR defines a new way to interpret DNS module and all its name servers:

Each nameserver (the client) could configure their options (e.g. tag, clientIP, queryStrategy) independently, while options specified in the DNS module are used as global default.

That is, a client for now could configure following options individually:

Inbound Tag
A special nameserver could name its inbound with a unique tag, thus made possible for domain-based DNS routing.
E.g. a server resolving geosite:bilibili gets named bilibili, and in routing it could be routed either directly or via HK proxy, to switch between different regions.

Client IP
Nameservers of same address could use different clientIP for different domains.

Fallback Strategy
A special nameserver serving geosite:bilibili may not expect to be used by other domains. Thus could be disabled from fallback individually.
On the other hand, when a domain matching geosite:bilibili, we also do not want the fallback servers to resolve it anymore, such could be set to disabledIfAnyMatch.

Cache Strategy
Each nameserver could disable cache individually.

Query Strategy
We could force certain domains to use only IPv4 or IPv6 address, if either route is preferred or with better quality.
A use case in transparent proxy:
In transparent proxy, we could specify all IPv6 packets go direct, but route all global IPv4 addresses to proxy (since when proxied, it normally doesn't matter whether dest is v4 or v6). Then, with queryStrategy, we could enforce all 1) global geosite domains, and 2) domains hit fallback server expecting non-CN IP to return only IPv4 IP, therefore gets routed to v2ray naturally.
This sorts of works like fakedns, but all resolved IPs are real, and v2ray does not take control of all traffic, only expected ones.

In this PR, following options are deprecated (but keep compatible with new options):

disableFallback, disableFallbackIfMatch, skipFallback: use fallbackStrategy.
disableCache: use cacheStrategy.

This PR also refactors the DNS module code, majorly to improve the readability and renders it more maintainable.

This PR does not introduce any change to existing features API. They'll be discussed and separated to future PRs.

codecov-commenter · 2022-09-12T15:39:59Z

Codecov Report

Base: 38.88% // Head: 38.81% // Decreases project coverage by -0.06% ⚠️

Coverage data is based on head (0669047) compared to base (2e0ea88).
Patch coverage: 44.66% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1977      +/-   ##
==========================================
- Coverage   38.88%   38.81%   -0.07%     
==========================================
  Files         616      608       -8     
  Lines       36336    36502     +166     
==========================================
+ Hits        14128    14170      +42     
- Misses      20630    20763     +133     
+ Partials     1578     1569       -9

Impacted Files	Coverage Δ
app/dns/config.pb.go	`11.16% <3.09%> (-1.27%)`	⬇️
app/dns/nameserver.go	`53.84% <53.84%> (+1.30%)`	⬆️
infra/conf/synthetic/dns/dns.go	`60.28% <56.66%> (-2.05%)`	⬇️
app/dns/dns.go	`56.27% <59.66%> (-0.61%)`	⬇️
app/dns/config.go	`80.64% <100.00%> (+12.22%)`	⬆️
features/dns/client.go	`100.00% <100.00%> (ø)`
app/router/command/errors.generated.go	`0.00% <0.00%> (-100.00%)`	⬇️
common/strmatcher/matchers.go	`64.78% <0.00%> (-14.38%)`	⬇️
testing/servers/tcp/tcp.go	`81.81% <0.00%> (-5.46%)`	⬇️
testing/scenarios/common.go	`75.00% <0.00%> (-4.29%)`	⬇️
... and 39 more

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Vigilans · 2022-09-14T13:03:02Z

app/dns/config.proto

  // DisableCache disables DNS cache
-  bool disableCache = 8;
+  // Deprecated. Use cache_strategy.
+  bool disableCache = 8 [deprecated = true];
+
+  // Deprecated. Use fallback_strategy.
+  bool disableFallback = 10 [deprecated = true];
+
+  // Deprecated. Use fallback_strategy.
+  bool disableFallbackIfMatch = 11 [deprecated = true];

+  // Default query strategy (IPv4, IPv6, or both) for each name server.
  QueryStrategy query_strategy = 9;

-  bool disableFallback = 10;
+  // Default cache strategy for each name server.
+  CacheStrategy cache_strategy = 12;

-  bool disableFallbackIfMatch = 11;
+  // Default fallback strategy for each name server.
+  FallbackStrategy fallback_strategy = 13;
 }


Seems for now SimplifiedConfig and SimplifiedNameServer is not used in infra/conf yet, should these fields marked deprecated or directly changed to reserved ?

I think marking deprecated is better.

Vigilans · 2022-09-14T15:11:23Z

Future works

Routing Strategy

This strategy aims to unify the three scenarios in routing dns inbound requests:

Default: sends to router normally.
SkipDNS: do not use internal DNS. Corresponds to session.Content.SkipDNSResolve.
Skip: do not use router. Corresponds to schemes like https+local://.

FakeDNS

Work on FakeDNS aims to remove FakeEnable member in dns.IPOption, ipOption and ctx member in DNS, and provide a new user-friendly way to configure FakeDNS.

Currently I may propose two ways and would like to know any of them would be a good idea:

Configure `fakedns` server objects independently from `servers`

Since fakedns is only enabled when using dns outbound, putting the fakedns server object along with other normal servers made the rules in servers hard to interpret when fakedns not enabled.

We may configure the fakedns server objects in a field sibling to servers field, and merge them to a full servers list when fakedns is enabled, at a certain priority:

"dns": {
    "tag": "dns",
    "servers": [
      {
        "address": "8.8.8.8",
        "domains": ["geosite:geolocation-!cn"]
      }
    ],
    "fakedns": {...}
}

Configure `fakedns` as an independent configuration in each nameserver object

As per FakeDNS | V2Fly.org and #789, integrating fakedns into servers is intended for rule-based dns resolution. In such case, it is the nameserver object that holds the rule semantic, but not the target DNS server address.

Therefore, we could integrate fakedns as a configurable option in a nameserver object, which will return fake ip instead of using original nameserver when fakedns is enabled (also a global default fakedns option):

"dns": {
    "tag": "dns",
    "servers": [
      {
        "address": "8.8.8.8",
        "domains": ["geosite:geolocation-!cn"],
        "fakedns": true
        // or 
        "fakedns": "xxx.xxx.xxx.xxx/xx"  // to return ips in a specific subnet?
      }
    ]
}

Geoip supports specifying IPv4 or IPv6 subsets (Backlog)

Currently, the expect IP "All ipv4 address and only CN ipv6 address" are conveyed as

expectIPs: ["0.0.0.0/0", "geoip:cn"] // ipv4 from geoip:cn just included in "0.0.0.0/0"

It would be better if we could express them as ["geoip:any@v4", "geoip:cn@v6"]
(Yes, also a new country code "any", where geoip:any@v4 = [0.0.0.0/0], geoip:any@v6 = [::/0])

Automatically creates a `geosite:builtin` domain list for all domains written in DNS and Outbound configs (Backlog)

Maintaining a list of all domains in v2ray config will help resolve many issues related to infinite loop.

Dispatch and forward non-A and AAAA requests (Backlog)

Currently, dns outbound only forwards A and AAAA requests to dns app, and forward all other requests to its original destination.

DNS app may also take other type of requests, but only does rules dispatching for them, and forwards the raw dns message to the dispatched destination.

Reserve original destination in DNS outbound (Backlog)

When dns outbound send the dns request to dns app, the latter does not hold any information about the original destination. Sometimes it may help (and simplify the config writing) if dns app has knowledge of the original destination.

kslr · 2022-09-16T06:29:06Z

cc @xiaokangwang

AkinoKaede · 2022-11-29T02:06:52Z

This is a very constructive PR and we should review the code and merge it as soon as possible.

AkinoKaede · 2022-11-29T08:00:09Z

I reviewed it again.

…disableFallback`, `disableFallbackIfMatch`

Vigilans force-pushed the vigilans/dns-per-client-configuration branch 3 times, most recently from 8329c15 to e393017 Compare September 12, 2022 14:47

DNS: Support per-client configuration

1655224

Vigilans force-pushed the vigilans/dns-per-client-configuration branch from e393017 to 1655224 Compare September 12, 2022 15:25

Vigilans mentioned this pull request Sep 12, 2022

Feat: [app/dns] Support specifying domain matcher (linear or mph) #1979

Merged

AkinoKaede requested review from Loyalsoldier and xiaokangwang and removed request for Loyalsoldier September 14, 2022 11:27

AkinoKaede approved these changes Sep 14, 2022

View reviewed changes

Vigilans commented Sep 14, 2022

View reviewed changes

kslr approved these changes Nov 29, 2022

View reviewed changes

Add deprecated feature warnings for skipFallback, disableCache, `…

0669047

…disableFallback`, `disableFallbackIfMatch`

AkinoKaede merged commit d3b50bb into v2fly:master Nov 30, 2022

Vigilans mentioned this pull request Dec 14, 2022

[app/dns] Support per-client configuration for fakedns #2212

Merged

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Feat: [app/dns] Support per-client configuration #1977

Feat: [app/dns] Support per-client configuration #1977

Vigilans commented Sep 12, 2022 •

edited

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codecov-commenter commented Sep 12, 2022 •

edited

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Vigilans Sep 14, 2022

AkinoKaede Sep 14, 2022

Vigilans commented Sep 14, 2022 •

edited

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kslr commented Sep 16, 2022

AkinoKaede commented Nov 29, 2022 •

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AkinoKaede commented Nov 29, 2022

Feat: [app/dns] Support per-client configuration #1977

Feat: [app/dns] Support per-client configuration #1977

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Vigilans commented Sep 12, 2022 • edited Loading

codecov-commenter commented Sep 12, 2022 • edited Loading

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Vigilans commented Sep 14, 2022 • edited Loading

Future works

Routing Strategy

FakeDNS

Configure fakedns server objects independently from servers

Configure fakedns as an independent configuration in each nameserver object

Geoip supports specifying IPv4 or IPv6 subsets (Backlog)

Automatically creates a geosite:builtin domain list for all domains written in DNS and Outbound configs (Backlog)

Dispatch and forward non-A and AAAA requests (Backlog)

Reserve original destination in DNS outbound (Backlog)

kslr commented Sep 16, 2022

AkinoKaede commented Nov 29, 2022 • edited Loading

AkinoKaede commented Nov 29, 2022

Vigilans commented Sep 12, 2022 •

edited

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codecov-commenter commented Sep 12, 2022 •

edited

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Vigilans commented Sep 14, 2022 •

edited

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Configure `fakedns` server objects independently from `servers`

Configure `fakedns` as an independent configuration in each nameserver object

Automatically creates a `geosite:builtin` domain list for all domains written in DNS and Outbound configs (Backlog)

AkinoKaede commented Nov 29, 2022 •

edited

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