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反向域名集合缓存咨询 #1618

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lonecale opened this issue Jan 9, 2024 · 11 comments
Open

反向域名集合缓存咨询 #1618

lonecale opened this issue Jan 9, 2024 · 11 comments

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@lonecale
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lonecale commented Jan 9, 2024 •
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需求简述：
我计划将 SmartDNS 用作某些特定域名的预加载服务。我的目标是让 SmartDNS 仅针对一个特定的域名列表进行操作，并且只对这些域名进行缓存处理。对于不在这个列表中的任何域名，SmartDNS 不进行缓存。

具体应用背景：
我想将 SmartDNS 配置成仅对我指定的某些域名进行解析和缓存，而不是对所有通过它解析的域名都进行缓存。这是为了优化特定域名。

配置方案细节：
bind：默认不禁用缓存
创建一个名为 test 的域名集合，并通过文件 /etc/smartdns/domain-set/test.txt 定义这个集合。
配置规则，以便 test 集合内的域名通过我指定的上游服务器（例如 test 服务器）进行解析。

domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /domain-set:test / -nameserver test

我想请教，是否有可能通过上述配置进行修改实现只对 test 域名集合中的域名进行缓存，而不缓存通过 SmartDNS 解析的其他所有域名？在不使用第二DNS服务器状况下
@PikuZheng
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最新代码的group功能好像可以实现，但是配置文件要怎么写我还没有搞清楚。可以先参考这个

@lonecale
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最新代码的group功能好像可以实现，但是配置文件要怎么写我还没有搞清楚。可以先参考这个

客户端规则好像只能针对指定的客户端，但是看了下好像也无法实现反向判断，并且在我的环境smartdns是局域网设备唯一DNS服务器，我希望的是所有设备都是这样。不是单一的

@pymumu
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pymumu commented Jan 10, 2024 •
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最新代码增加了相关的能力

domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /./ -no-cache

group-begin test
group-match -domain domain-set:test
group-end

如果是老代码
可以通过设置TTL超时时间来实现类似的效果

rr-ttl 1
rr-ttl-max 1
domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /domain-set:test / -nameserver test -rr-ttl-min 600

@lonecale
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domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /domain-set:test / -nameserver test -rr-ttl-min 600

感谢
那像下面的配置应该都可以实现 只有test域名预加载缓存非test 不缓存

老代码

serve-expired no
prefetch-domain yes
cache-persist yes
cache-size 20000
cache-checkpoint-time 3600
rr-ttl 1
rr-ttl-max 1
domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /domain-set:test / -nameserver test -rr-ttl-min 600

新代码

serve-expired no
prefetch-domain yes
cache-persist yes
cache-size 20000
cache-checkpoint-time 3600
domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /./ -no-cache

group-begin test
group-match -domain domain-set:test
group-end

@lonecale
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lonecale commented Jan 13, 2024 •
edited
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最新代码增加了相关的能力

domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /./ -no-cache

group-begin test
group-match -domain domain-set:test
group-end

如果是老代码 可以通过设置TTL超时时间来实现类似的效果

rr-ttl 1
rr-ttl-max 1
domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /domain-set:test / -nameserver test -rr-ttl-min 600

在比较最新版本的SmartDNS和之前的Release 43版本时，我发现了一个差异。在最新版本中，即使在接收到响应代码为0的情况下(没有有效的返回)，系统仍会尝试重新发送请求。而在Release 43版本中，这种情况不会引发重试。这一点尤其显著，因为当上游DNS针对一个特定域名进行拦截并返回响应代码0时，按照正常逻辑，系统不应该进行重试。不太清楚这是什么情况

版本号:1.2023.v43.0.78
[2024-01-14 00:33:16,624][DEBUG][     dns_client.c:1799] qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 44, id = 14312, tc = 0, rd = 1, ra = 1, rcode = 0, payloadsize = 1200
[2024-01-14 00:33:16,624][DEBUG][     dns_client.c:1811] domain: www.youtube.com qtype: 28  qclass: 1
[2024-01-14 00:33:16,624][DEBUG][     dns_server.c:4173] query result from server 127.0.0.1:5353, type: 0, domain: www.youtube.com qtype: 28 rcode: 0, id: 44195
[2024-01-14 00:33:16,624][DEBUG][     dns_server.c:3749] no result, www.youtube.com qtype: 28, rcode: 0, id: 14312, retry
[2024-01-14 00:33:17,123][DEBUG][     dns_client.c:4449] retry query www.youtube.com, type: 28, id: 14312
[2024-01-14 00:33:17,123][DEBUG][     dns_client.c:3775] send query to server 127.0.0.1:5353
[2024-01-14 00:33:17,124][DEBUG][     dns_client.c:2531] recv udp packet from 127.0.0.1, len: 44, ttl: 64, latency: 0
[2024-01-14 00:33:17,124][DEBUG][     dns_client.c:1799] qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 44, id = 14312, tc = 0, rd = 1, ra = 1, rcode = 0, payloadsize = 1200
[2024-01-14 00:33:17,124][DEBUG][     dns_client.c:1811] domain: www.youtube.com qtype: 28  qclass: 1
[2024-01-14 00:33:17,124][DEBUG][     dns_server.c:4173] query result from server 127.0.0.1:5353, type: 0, domain: www.youtube.com qtype: 28 rcode: 0, id: 44195
[2024-01-14 00:33:17,124][DEBUG][     dns_server.c:3749] no result, www.youtube.com qtype: 28, rcode: 0, id: 14312, retry
[2024-01-14 00:33:17,723][DEBUG][     dns_client.c:4449] retry query www.youtube.com, type: 28, id: 14312
[2024-01-14 00:33:17,723][DEBUG][     dns_client.c:3775] send query to server 127.0.0.1:5353
[2024-01-14 00:33:17,724][DEBUG][     dns_client.c:2531] recv udp packet from 127.0.0.1, len: 44, ttl: 64, latency: 0
[2024-01-14 00:33:17,724][DEBUG][     dns_client.c:1799] qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 44, id = 14312, tc = 0, rd = 1, ra = 1, rcode = 0, payloadsize = 1200
[2024-01-14 00:33:17,724][DEBUG][     dns_client.c:1811] domain: www.youtube.com qtype: 28  qclass: 1
[2024-01-14 00:33:17,724][DEBUG][     dns_server.c:4173] query result from server 127.0.0.1:5353, type: 0, domain: www.youtube.com qtype: 28 rcode: 0, id: 44195
[2024-01-14 00:33:17,724][DEBUG][     dns_server.c:3749] no result, www.youtube.com qtype: 28, rcode: 0, id: 14312, retry
[2024-01-14 00:33:18,107][DEBUG][     dns_server.c:6506] recv query packet from 127.0.0.1, len = 33, type = 0
[2024-01-14 00:33:18,107][DEBUG][     dns_server.c:6518] request qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 33, id = 34726, tc = 0, rd = 1, ra = 0, rcode = 0
[2024-01-14 00:33:18,107][DEBUG][     dns_server.c:6542] query www.youtube.com from 127.0.0.1, qtype: 28, id: 34726, query-num: 2
[2024-01-14 00:33:18,323][DEBUG][     dns_client.c:4446] retry query www.youtube.com, type: 28, id: 14312 failed
[2024-01-14 00:33:18,323][DEBUG][     dns_client.c:1563] result: www.youtube.com, qtype: 28, has-result: 0, id 14312
[2024-01-14 00:33:18,323][ INFO][     dns_server.c:2455] result: www.youtube.com, qtype: 28, rtt: -0.1 ms, 0000:0000:0000:0000:0000:0000:0000:0000
[2024-01-14 00:33:18,323][DEBUG][     dns_server.c:2174] reply www.youtube.com qtype: 28, rcode: 0, reply: 1
[2024-01-14 00:33:18,323][ INFO][     dns_server.c:2229] result: www.youtube.com, client: 127.0.0.1, qtype: 28, id: 44195, group: default, time: 2288ms
[2024-01-14 00:33:18,323][ INFO][     dns_server.c:4053] result: www.youtube.com, client: 127.0.0.1, qtype: 28, id: 34726, group: default, time: 217ms

版本号:Release43-1
[2024-01-14 01:02:41,201][ INFO][     dns_server.c:4537] query server youtube.com from 127.0.0.1, qtype = 28
[2024-01-14 01:02:41,201][DEBUG][     dns_client.c:535 ] send query to group default
[2024-01-14 01:02:41,201][DEBUG][     dns_client.c:2910] send query to server 127.0.0.1
[2024-01-14 01:02:41,202][ INFO][     dns_client.c:3206] send request youtube.com, qtype 28, id 4
[2024-01-14 01:02:41,202][DEBUG][     dns_client.c:2021] recv udp packet from 127.0.0.1, len: 40, ttl: 64
[2024-01-14 01:02:41,202][DEBUG][     dns_client.c:1613] qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 40, id = 4, tc = 0, rd = 1, ra = 1, rcode = 0, payloadsize = 1200
[2024-01-14 01:02:41,202][DEBUG][     dns_client.c:1624] domain: youtube.com qtype: 28  qclass: 1
[2024-01-14 01:02:41,202][DEBUG][     dns_server.c:3086] query result from server 127.0.0.1: 5353, type: 0
[2024-01-14 01:02:41,202][DEBUG][     dns_client.c:1403] result: youtube.com, qtype: 28, hasresult: 1, id 4
[2024-01-14 01:02:41,202][DEBUG][     dns_server.c:1538] reply youtube.com qtype: 28, rcode: 0, reply: 1
[2024-01-14 01:02:41,202][DEBUG][     dns_server.c:1063] cache youtube.com qtype: 28 ttl: 0

@pymumu
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pymumu commented Jan 14, 2024

RCODE=0，且没有任何结果的情况，在某些上游查询会出现此问题，所以增加重试避免没有结果。

不清楚你的场景是什么。

@lonecale
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lonecale commented Jan 14, 2024 •
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RCODE=0，且没有任何结果的情况，在某些上游查询会出现此问题，所以增加重试避免没有结果。

不清楚你的场景是什么。

这个情况易出现，在双栈环境当中访问一个域名并且该域名没有IPV6的时候，大多数DNS都是这样返回，RCODE=0，且没有有效返回。重试很容易增加延迟，降低体验，哪怕配置双栈优选也是前提IPV6解析出来。

@pymumu
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pymumu commented Jan 14, 2024

按照协议，如果没有IPV6，会有一条SOA记录的。不会返回只有question的记录。

如果返回了只包含question，而没有answer记录，这条记录是会被标记为truncated的。属于无效结果，协议上是要求重新用TCP之类的协议查询的。

@pymumu
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pymumu commented Jan 14, 2024

想了一下，可以做一下细化判断，如果确认是truncated记录才重试，否则只是没有结果的记录，但非truncated，认为结果OK。

最新代码改了下，验证下看看吧。

@lonecale
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想了一下，可以做一下细化判断，如果确认是truncated记录才重试，否则只是没有结果的记录，但非truncated，认为结果OK。

最新代码改了下，验证下看看吧。

看下面日志 最新代码在rcode 0下没有answer记录 是正常了


[2024-01-14 22:32:42,895][DEBUG][     dns_server.c:6542] query www.youtube.com from 127.0.0.1, qtype: 28, id: 37801, query-num: 2
[2024-01-14 22:32:42,895][DEBUG][     dns_client.c:3780] send query to server 127.0.0.1:5353
[2024-01-14 22:32:42,895][ INFO][     dns_client.c:4171] request: www.youtube.com, qtype: 28, id: 40680, group: default
[2024-01-14 22:32:42,896][DEBUG][     dns_client.c:2536] recv udp packet from 127.0.0.1, len: 44, ttl: 64, latency: 1
[2024-01-14 22:32:42,896][DEBUG][     dns_client.c:1800] qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 44, id = 40680, tc = 0, rd = 1, ra = 1, rcode = 0, payloadsize = 1200
[2024-01-14 22:32:42,896][DEBUG][     dns_client.c:1812] domain: www.youtube.com qtype: 28 qclass: 1
[2024-01-14 22:32:42,896][DEBUG][     dns_server.c:4173] query result from server 127.0.0.1:5353, type: 0, domain: www.youtube.com qtype: 28 rcode: 0, id: 37801
[2024-01-14 22:32:42,896][DEBUG][     dns_client.c:1564] result: www.youtube.com, qtype: 28, has-result: 1, id 40680
[2024-01-14 22:32:42,896][ INFO][     dns_server.c:2455] result: www.youtube.com, qtype: 28, rtt: -0.1 ms, 0000:0000:0000:0000:0000:0000:0000:0000
[2024-01-14 22:32:42,896][DEBUG][     dns_server.c:2174] reply www.youtube.com qtype: 28, rcode: 0, reply: 1
[2024-01-14 22:32:42,896][ INFO][     dns_server.c:2229] result: www.youtube.com, client: 127.0.0.1, qtype: 28, id: 37801, group: default, time: 1ms

测试其他的同样情况时候好像还是会重试，例如rcode:5的部分响应返回，正常rcode 5 不是直接拒绝吗？

[2024-01-14 22:45:23,548][DEBUG][     dns_server.c:6542] query adguard-dns.io from 127.0.0.1, qtype: 28, id: 43059, query-num: 2
[2024-01-14 22:45:23,548][DEBUG][     dns_client.c:3780] send query to server 127.0.0.1:5353
[2024-01-14 22:45:23,548][ INFO][     dns_client.c:4171] request: adguard-dns.io, qtype: 28, id: 17406, group: default
[2024-01-14 22:45:23,548][DEBUG][     dns_client.c:2536] recv udp packet from 127.0.0.1, len: 43, ttl: 64, latency: 1
[2024-01-14 22:45:23,548][DEBUG][     dns_client.c:1800] qdcount = 1, ancount = 0, nscount = 0, nrcount= 0, len = 43, id = 17406, tc = 0, rd = 1, ra = 1, rcode = 5, payloadsize = 1200
[2024-01-14 22:45:23,548][DEBUG][ dns_client.c:1812] domain: adguard-dns.io qtype: 28 qclass: 1
[2024-01-14 22:45:23,548][DEBUG][ dns_server.c:4173] query result from server 127.0.0.1:5353, type: 0, domain:adguard-dns.io qtype: 28 rcode: 5, id: 43059
[2024-01-14 22:45:23,548][DEBUG][ dns_server.c:3661] inquery failed, adguard-dns.io, rcode = 5, id = 17406
[2024-01-14 22:45:24,049][DEBUG][ dns_client.c:4052] retry query adguard-dns.io, type: 28, id: 17406
[2024-01-14 22:45:24,049][DEBUG][ dns_client.c:3780] send query to server 127.0.0.1:5353
[2024-01-14 22:45:24,049][DEBUG][ dns_client.c:2536] recv udp packet from 127.0.0.1, len: 43, ttl: 64, latency: 1
[2024-01-14 22:45:24,049][DEBUG][ dns_client.c:1800] qdcount = 1, ancount = 0, nscount = 0, nrcount = 0, len = 43, id = 17406, tc = 0, rd = 1, ra = 1, rcode = 5, payloadsize = 1200

@lonecale
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lonecale commented Jan 14, 2024 •
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最新代码的group功能好像可以实现，但是配置文件要怎么写我还没有搞清楚。可以先参考这个

发现新版本有个更简单的方式实现 先在服务端bind 配置直接no-cache

domain-set -name test -file '/etc/smartdns/domain-set/test.txt'
domain-rules /domain-set:test/ -enable-cache

然后针对域名集合开启缓存就可以了

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@pymumu @PikuZheng @lonecale