recursive

package module
v0.18.0 Latest Latest
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 Go to latest Published: Oct 1, 2025 License: MIT Imports: 20 Imported by: 0

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recursive

Recursive DNS resolver with QNAME minimization and optional cache.

package main

import (
	"context"
	"fmt"
	"time"

	"github.com/linkdata/recursive"
	"github.com/miekg/dns"
)

func main() {
	rec := recursive.New(nil)
	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
	defer cancel()
	msg, srv, err := rec.DnsResolve(ctx, "one.one.one.one", dns.TypeA)
	if err != nil {
		panic(err)
	}
	fmt.Println(msg)
    fmt.Println(";; SERVER ", srv)
}

The resolver can log query details. To protect privacy, logs only include the first few characters of the client and server cookie values.

Some servers don't handle QNAME minimization well. In that case, we fall back to normal resolution. For example, here is the output with debug logging for A console.aws.amazon.com:

$ go run ./cmd/cli -debug A console.aws.amazon.com
[0      1]  QUERY NS "com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[0      1]  SENDING udp4: @198.41.0.4 NS "com." COOKIE:c="55d80081..." s="" => NOERROR [0+13+27 A/N/E] (3ms, 1527 bytes)
[3      1]  QUERY NS "amazon.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[3      1]  SENDING udp4: @192.5.6.30 NS "amazon.com." COOKIE:c="55d80081..." s="" => NOERROR [0+8+5 A/N/E] (22ms, 503 bytes)
[26     1]  QUERY NS "aws.amazon.com." from [ns1.amzndns.com. 156.154.64.10 ns2.amzndns.com. 156.154.68.10 ns1.amzndns.net. ns1.amzndns.org.]
[26     1]  SENDING udp4: @156.154.64.10 NS "aws.amazon.com." COOKIE:c="55d80081..." s="" => NOERROR [1+4+1 A/N/E] (2ms, 359 bytes AUTH)
[29     1]  QUERY NS "console.aws.amazon.com." from [ns-1172.awsdns-18.org. ns-439.awsdns-54.com. ns-959.awsdns-55.net. ns-2017.awsdns-60.co.uk.]
[29     1]  GLUE lookup for NS "ns-1172.awsdns-18.org."
[29     2]   QUERY A "org." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[29     2]   SENDING udp4: @198.41.0.4 A "org." => NOERROR [0+6+13 A/N/E] (2ms, 803 bytes)
[30     2]   QUERY A "awsdns-18.org." from [c0.org.afilias-nst.info. 199.19.53.1 b0.org.afilias-nst.org. 199.19.54.1 a0.org.afilias-nst.info. 199.19.56.1 d0.org.afilias-nst.org. 199.19.57.1]
[30     2]   SENDING udp4: @199.19.53.1 A "awsdns-18.org." COOKIE:c="55d80081..." s="" => NOERROR [0+4+9 A/N/E] (255ms, 596 bytes)
[286    2]   QUERY A "ns-1172.awsdns-18.org." from [g-ns-146.awsdns-18.org. 205.251.192.146 g-ns-724.awsdns-18.org. 205.251.194.212 g-ns-1045.awsdns-18.org. 205.251.196.21 g-ns-1618.awsdns-18.org. 205.251.198.82]
[286    2]   SENDING udp4: @205.251.192.146 A "ns-1172.awsdns-18.org." COOKIE:c="55d80081..." s="" => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[289    2]   QUERY FINAL A "ns-1172.awsdns-18.org." from [g-ns-146.awsdns-18.org. 205.251.192.146 g-ns-724.awsdns-18.org. 205.251.194.212 g-ns-1045.awsdns-18.org. 205.251.196.21 g-ns-1618.awsdns-18.org. 205.251.198.82]
[290    2]   cached answer: A "ns-1172.awsdns-18.org." => NOERROR [1+4+9 A/N/E] AUTH
[290    2]   final nameservers: [205.251.192.146 205.251.194.212 205.251.196.21 205.251.198.82]
[290    2]   cached answer: A "ns-1172.awsdns-18.org." => NOERROR [1+4+9 A/N/E] AUTH
[290    2]   ANSWER NOERROR for A "ns-1172.awsdns-18.org." with 1 records
[290    1]  SENDING udp4: @205.251.196.148 NS "console.aws.amazon.com." COOKIE:c="55d80081..." s="" => REFUSED [0+0+0 A/N/E] (5ms, 40 bytes)
[295    1]  got REFUSED, retry without QNAME minimization
[295    2]   QUERY A "console.aws.amazon.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[295    2]   SENDING udp4: @198.41.0.4 A "console.aws.amazon.com." => NOERROR [0+13+27 A/N/E] (2ms, 1546 bytes)
[298    2]   QUERY A "console.aws.amazon.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[298    2]   SENDING udp4: @192.5.6.30 A "console.aws.amazon.com." => NOERROR [0+8+5 A/N/E] (23ms, 515 bytes)
[321    2]   QUERY A "console.aws.amazon.com." from [ns1.amzndns.com. 156.154.64.10 ns2.amzndns.com. 156.154.68.10 ns1.amzndns.net. ns1.amzndns.org.]
[321    2]   SENDING udp4: @156.154.64.10 A "console.aws.amazon.com." => NOERROR [1+4+1 A/N/E] (2ms, 345 bytes AUTH)
[324    2]   CNAME QUERY "console.aws.amazon.com." => "console.cname-proxy.amazon.com."
[324    3]    QUERY A "console.cname-proxy.amazon.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[324    3]    SENDING udp4: @198.41.0.4 A "console.cname-proxy.amazon.com." => NOERROR [0+13+27 A/N/E] (2ms, 1554 bytes)
[326    3]    QUERY A "console.cname-proxy.amazon.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[326    3]    SENDING udp4: @192.5.6.30 A "console.cname-proxy.amazon.com." => NOERROR [0+8+5 A/N/E] (24ms, 523 bytes)
[350    3]    QUERY A "console.cname-proxy.amazon.com." from [ns1.amzndns.com. 156.154.64.10 ns2.amzndns.com. 156.154.68.10 ns1.amzndns.net. ns1.amzndns.org.]
[350    3]    SENDING udp4: @156.154.64.10 A "console.cname-proxy.amazon.com." => NOERROR [0+4+1 A/N/E] (2ms, 287 bytes)
[353    3]    QUERY A "console.cname-proxy.amazon.com." from [ns-1313.awsdns-36.org. ns-429.awsdns-53.com. ns-689.awsdns-22.net. ns-1878.awsdns-42.co.uk.]
[353    3]    GLUE lookup for NS "ns-1313.awsdns-36.org."
[353    4]     QUERY A "ns-1313.awsdns-36.org." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[353    4]     SENDING udp4: @198.41.0.4 A "ns-1313.awsdns-36.org." => NOERROR [0+6+13 A/N/E] (2ms, 821 bytes)
[354    4]     QUERY A "ns-1313.awsdns-36.org." from [c0.org.afilias-nst.info. 199.19.53.1 b0.org.afilias-nst.org. 199.19.54.1 a0.org.afilias-nst.info. 199.19.56.1 d0.org.afilias-nst.org. 199.19.57.1]
[354    4]     SENDING udp4: @199.19.53.1 A "ns-1313.awsdns-36.org." => NOERROR [0+4+9 A/N/E] (261ms, 604 bytes)
[615    4]     QUERY A "ns-1313.awsdns-36.org." from [g-ns-164.awsdns-36.org. 205.251.192.164 g-ns-742.awsdns-36.org. 205.251.194.230 g-ns-1063.awsdns-36.org. 205.251.196.39 g-ns-1636.awsdns-36.org. 205.251.198.100]
[615    4]     SENDING udp4: @205.251.192.164 A "ns-1313.awsdns-36.org." COOKIE:c="55d80081..." s="" => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[618    4]     QUERY FINAL A "ns-1313.awsdns-36.org." from [g-ns-164.awsdns-36.org. 205.251.192.164 g-ns-742.awsdns-36.org. 205.251.194.230 g-ns-1063.awsdns-36.org. 205.251.196.39 g-ns-1636.awsdns-36.org. 205.251.198.100]
[618    4]     SENDING udp4: @205.251.192.164 A "ns-1313.awsdns-36.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[620    4]     final nameservers: [205.251.192.164 205.251.194.230 205.251.196.39 205.251.198.100]
[620    4]     SENDING udp4: @205.251.192.164 A "ns-1313.awsdns-36.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[623    4]     ANSWER NOERROR for A "ns-1313.awsdns-36.org." with 1 records
[623    3]    SENDING udp4: @205.251.197.33 A "console.cname-proxy.amazon.com." COOKIE:c="55d80081..." s="" => NOERROR [1+4+1 A/N/E] (5ms, 359 bytes AUTH)
[628    3]    CNAME QUERY "console.cname-proxy.amazon.com." => "lbr.us.console.amazonaws.com."
[628    4]     QUERY A "lbr.us.console.amazonaws.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[628    4]     SENDING udp4: @198.41.0.4 A "lbr.us.console.amazonaws.com." => NOERROR [0+13+27 A/N/E] (2ms, 1552 bytes)
[630    4]     QUERY A "lbr.us.console.amazonaws.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[630    4]     SENDING udp4: @192.5.6.30 A "lbr.us.console.amazonaws.com." => NOERROR [0+4+2 A/N/E] (23ms, 283 bytes)
[653    4]     QUERY A "lbr.us.console.amazonaws.com." from [ns-27.awsdns-03.com. 205.251.192.27 ns-1321.awsdns-37.org. ns-967.awsdns-56.net. ns-1670.awsdns-16.co.uk.]
[653    4]     SENDING udp4: @205.251.192.27 A "lbr.us.console.amazonaws.com." COOKIE:c="55d80081..." s="" => NOERROR [0+4+1 A/N/E] (2ms, 281 bytes)
[656    4]     QUERY A "lbr.us.console.amazonaws.com." from [ns-1342.awsdns-39.org. ns-372.awsdns-46.com. ns-671.awsdns-19.net. ns-1832.awsdns-37.co.uk.]
[656    4]     GLUE lookup for NS "ns-1342.awsdns-39.org."
[656    5]      QUERY A "ns-1342.awsdns-39.org." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[656    5]      SENDING udp4: @198.41.0.4 A "ns-1342.awsdns-39.org." => NOERROR [0+6+13 A/N/E] (1ms, 821 bytes)
[657    5]      QUERY A "ns-1342.awsdns-39.org." from [c0.org.afilias-nst.info. 199.19.53.1 b0.org.afilias-nst.org. 199.19.54.1 a0.org.afilias-nst.info. 199.19.56.1 d0.org.afilias-nst.org. 199.19.57.1]
[657    5]      SENDING udp4: @199.19.53.1 A "ns-1342.awsdns-39.org." => NOERROR [0+4+9 A/N/E] (268ms, 604 bytes)
[925    5]      QUERY A "ns-1342.awsdns-39.org." from [g-ns-167.awsdns-39.org. 205.251.192.167 g-ns-745.awsdns-39.org. 205.251.194.233 g-ns-1066.awsdns-39.org. 205.251.196.42 g-ns-1639.awsdns-39.org. 205.251.198.103]
[926    5]      SENDING udp4: @205.251.192.167 A "ns-1342.awsdns-39.org." COOKIE:c="55d80081..." s="" => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[928    5]      QUERY FINAL A "ns-1342.awsdns-39.org." from [g-ns-167.awsdns-39.org. 205.251.192.167 g-ns-745.awsdns-39.org. 205.251.194.233 g-ns-1066.awsdns-39.org. 205.251.196.42 g-ns-1639.awsdns-39.org. 205.251.198.103]
[928    5]      SENDING udp4: @205.251.192.167 A "ns-1342.awsdns-39.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[931    5]      final nameservers: [205.251.192.167 205.251.194.233 205.251.196.42 205.251.198.103]
[931    5]      SENDING udp4: @205.251.192.167 A "ns-1342.awsdns-39.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[934    5]      ANSWER NOERROR for A "ns-1342.awsdns-39.org." with 1 records
[934    4]     SENDING udp4: @205.251.197.62 A "lbr.us.console.amazonaws.com." COOKIE:c="55d80081..." s="" => NOERROR [0+4+1 A/N/E] (4ms, 293 bytes)
[939    4]     QUERY A "lbr.us.console.amazonaws.com." from [ns-1335.awsdns-38.org. ns-499.awsdns-62.com. ns-611.awsdns-12.net. ns-1892.awsdns-44.co.uk.]
[939    4]     GLUE lookup for NS "ns-1335.awsdns-38.org."
[939    5]      QUERY A "ns-1335.awsdns-38.org." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[939    5]      SENDING udp4: @198.41.0.4 A "ns-1335.awsdns-38.org." => NOERROR [0+6+13 A/N/E] (2ms, 821 bytes)
[941    5]      QUERY A "ns-1335.awsdns-38.org." from [c0.org.afilias-nst.info. 199.19.53.1 b0.org.afilias-nst.org. 199.19.54.1 a0.org.afilias-nst.info. 199.19.56.1 d0.org.afilias-nst.org. 199.19.57.1]
[941    5]      SENDING udp4: @199.19.53.1 A "ns-1335.awsdns-38.org." => NOERROR [0+4+9 A/N/E] (265ms, 604 bytes)
[1206   5]      QUERY A "ns-1335.awsdns-38.org." from [g-ns-166.awsdns-38.org. 205.251.192.166 g-ns-744.awsdns-38.org. 205.251.194.232 g-ns-1065.awsdns-38.org. 205.251.196.41 g-ns-1638.awsdns-38.org. 205.251.198.102]
[1206   5]      SENDING udp4: @205.251.192.166 A "ns-1335.awsdns-38.org." COOKIE:c="55d80081..." s="" => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[1209   5]      QUERY FINAL A "ns-1335.awsdns-38.org." from [g-ns-166.awsdns-38.org. 205.251.192.166 g-ns-744.awsdns-38.org. 205.251.194.232 g-ns-1065.awsdns-38.org. 205.251.196.41 g-ns-1638.awsdns-38.org. 205.251.198.102]
[1209   5]      SENDING udp4: @205.251.192.166 A "ns-1335.awsdns-38.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[1212   5]      final nameservers: [205.251.192.166 205.251.194.232 205.251.196.41 205.251.198.102]
[1212   5]      SENDING udp4: @205.251.192.166 A "ns-1335.awsdns-38.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[1215   5]      ANSWER NOERROR for A "ns-1335.awsdns-38.org." with 1 records
[1215   4]     SENDING udp4: @205.251.197.55 A "lbr.us.console.amazonaws.com." COOKIE:c="55d80081..." s="" => NOERROR [1+4+1 A/N/E] (5ms, 368 bytes AUTH)
[1220   4]     CNAME QUERY "lbr.us.console.amazonaws.com." => "eu-north-1.console.aws.amazon.com."
[1220   5]      QUERY A "eu-north-1.console.aws.amazon.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[1220   5]      SENDING udp4: @198.41.0.4 A "eu-north-1.console.aws.amazon.com." => NOERROR [0+13+27 A/N/E] (2ms, 1557 bytes)
[1223   5]      QUERY A "eu-north-1.console.aws.amazon.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[1223   5]      SENDING udp4: @192.5.6.30 A "eu-north-1.console.aws.amazon.com." => NOERROR [0+8+5 A/N/E] (23ms, 526 bytes)
[1246   5]      QUERY A "eu-north-1.console.aws.amazon.com." from [ns1.amzndns.com. 156.154.64.10 ns2.amzndns.com. 156.154.68.10 ns1.amzndns.net. ns1.amzndns.org.]
[1246   5]      SENDING udp4: @156.154.64.10 A "eu-north-1.console.aws.amazon.com." => NOERROR [1+4+1 A/N/E] (3ms, 378 bytes AUTH)
[1249   5]      CNAME QUERY "eu-north-1.console.aws.amazon.com." => "eu-north-1.console.cname-proxy.amazon.com."
[1249   6]       QUERY A "eu-north-1.console.cname-proxy.amazon.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[1249   6]       SENDING udp4: @198.41.0.4 A "eu-north-1.console.cname-proxy.amazon.com." => NOERROR [0+13+27 A/N/E] (2ms, 1565 bytes)
[1251   6]       QUERY A "eu-north-1.console.cname-proxy.amazon.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[1251   6]       SENDING udp4: @192.5.6.30 A "eu-north-1.console.cname-proxy.amazon.com." => NOERROR [0+8+5 A/N/E] (21ms, 534 bytes)
[1273   6]       QUERY A "eu-north-1.console.cname-proxy.amazon.com." from [ns1.amzndns.com. 156.154.64.10 ns2.amzndns.com. 156.154.68.10 ns1.amzndns.net. ns1.amzndns.org.]
[1273   6]       SENDING udp4: @156.154.64.10 A "eu-north-1.console.cname-proxy.amazon.com." => NOERROR [0+4+1 A/N/E] (2ms, 298 bytes)
[1275   6]       QUERY A "eu-north-1.console.cname-proxy.amazon.com." from [ns-1313.awsdns-36.org. 205.251.197.33 ns-429.awsdns-53.com. ns-689.awsdns-22.net. ns-1878.awsdns-42.co.uk.]
[1275   6]       SENDING udp4: @205.251.197.33 A "eu-north-1.console.cname-proxy.amazon.com." => NOERROR [1+4+1 A/N/E] (4ms, 396 bytes AUTH)
[1279   6]       CNAME QUERY "eu-north-1.console.cname-proxy.amazon.com." => "gr.aga.console-geo.eu-north-1.amazonaws.com."
[1279   7]        QUERY A "gr.aga.console-geo.eu-north-1.amazonaws.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[1279   7]        SENDING udp4: @198.41.0.4 A "gr.aga.console-geo.eu-north-1.amazonaws.com." => NOERROR [0+13+27 A/N/E] (3ms, 1567 bytes)
[1282   7]        QUERY A "gr.aga.console-geo.eu-north-1.amazonaws.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[1282   7]        SENDING udp4: @192.5.6.30 A "gr.aga.console-geo.eu-north-1.amazonaws.com." => NOERROR [0+4+2 A/N/E] (23ms, 298 bytes)
[1305   7]        QUERY A "gr.aga.console-geo.eu-north-1.amazonaws.com." from [ns-27.awsdns-03.com. 205.251.192.27 ns-1321.awsdns-37.org. ns-967.awsdns-56.net. ns-1670.awsdns-16.co.uk.]
[1305   7]        SENDING udp4: @205.251.192.27 A "gr.aga.console-geo.eu-north-1.amazonaws.com." => NOERROR [0+8+1 A/N/E] (2ms, 500 bytes)
[1307   7]        QUERY A "gr.aga.console-geo.eu-north-1.amazonaws.com." from [ns1.amzndns.com. 156.154.64.10 ns2.amzndns.com. 156.154.68.10 ns1.amzndns.net. ns1.amzndns.org.]
[1307   7]        SENDING udp4: @156.154.64.10 A "gr.aga.console-geo.eu-north-1.amazonaws.com." => NOERROR [0+4+1 A/N/E] (2ms, 356 bytes)
[1309   7]        QUERY A "gr.aga.console-geo.eu-north-1.amazonaws.com." from [ns-1055.awsdns-03.org. ns-148.awsdns-18.com. ns-581.awsdns-08.net. ns-1737.awsdns-25.co.uk.]
[1309   7]        GLUE lookup for NS "ns-1055.awsdns-03.org."
[1309   8]         QUERY A "ns-1055.awsdns-03.org." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[1309   8]         SENDING udp4: @198.41.0.4 A "ns-1055.awsdns-03.org." => NOERROR [0+6+13 A/N/E] (2ms, 821 bytes)
[1311   8]         QUERY A "ns-1055.awsdns-03.org." from [c0.org.afilias-nst.info. 199.19.53.1 b0.org.afilias-nst.org. 199.19.54.1 a0.org.afilias-nst.info. 199.19.56.1 d0.org.afilias-nst.org. 199.19.57.1]
[1311   8]         SENDING udp4: @199.19.53.1 A "ns-1055.awsdns-03.org." => NOERROR [0+4+9 A/N/E] (257ms, 604 bytes)
[1569   8]         QUERY A "ns-1055.awsdns-03.org." from [g-ns-131.awsdns-03.org. 205.251.192.131 g-ns-709.awsdns-03.org. 205.251.194.197 g-ns-1030.awsdns-03.org. 205.251.196.6 g-ns-1603.awsdns-03.org. 205.251.198.67]
[1569   8]         SENDING udp4: @205.251.192.131 A "ns-1055.awsdns-03.org." COOKIE:c="55d80081..." s="" => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[1571   8]         QUERY FINAL A "ns-1055.awsdns-03.org." from [g-ns-131.awsdns-03.org. 205.251.192.131 g-ns-709.awsdns-03.org. 205.251.194.197 g-ns-1030.awsdns-03.org. 205.251.196.6 g-ns-1603.awsdns-03.org. 205.251.198.67]
[1571   8]         SENDING udp4: @205.251.192.131 A "ns-1055.awsdns-03.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[1573   8]         final nameservers: [205.251.192.131 205.251.194.197 205.251.196.6 205.251.198.67]
[1573   8]         SENDING udp4: @205.251.192.131 A "ns-1055.awsdns-03.org." => NOERROR [1+4+9 A/N/E] (2ms, 641 bytes AUTH)
[1575   8]         ANSWER NOERROR for A "ns-1055.awsdns-03.org." with 1 records
[1575   7]        SENDING udp4: @205.251.196.31 A "gr.aga.console-geo.eu-north-1.amazonaws.com." COOKIE:c="55d80081..." s="" => NOERROR [1+4+1 A/N/E] (4ms, 455 bytes AUTH)
[1579   7]        CNAME QUERY "gr.aga.console-geo.eu-north-1.amazonaws.com." => "aba8735d2c3d241de.awsglobalaccelerator.com."
[1579   8]         QUERY A "aba8735d2c3d241de.awsglobalaccelerator.com." from [root 198.41.0.4 root 192.36.148.17 root 192.203.230.10 root 192.5.5.241]
[1579   8]         SENDING udp4: @198.41.0.4 A "aba8735d2c3d241de.awsglobalaccelerator.com." => NOERROR [0+13+27 A/N/E] (2ms, 1566 bytes)
[1581   8]         QUERY A "aba8735d2c3d241de.awsglobalaccelerator.com." from [a.gtld-servers.net. 192.5.6.30 e.gtld-servers.net. 192.12.94.30 c.gtld-servers.net. 192.26.92.30 d.gtld-servers.net. 192.31.80.30]
[1581   8]         SENDING udp4: @192.5.6.30 A "aba8735d2c3d241de.awsglobalaccelerator.com." => NOERROR [0+4+2 A/N/E] (23ms, 343 bytes)
[1605   8]         QUERY A "aba8735d2c3d241de.awsglobalaccelerator.com." from [ns-409.awsdns-51.com. 205.251.193.153 ns-1484.awsdns-57.org. ns-609.awsdns-12.net. ns-1949.awsdns-51.co.uk.]
[1605   8]         SENDING udp4: @205.251.193.153 A "aba8735d2c3d241de.awsglobalaccelerator.com." COOKIE:c="55d80081..." s="" => NOERROR [2+4+1 A/N/E] (2ms, 423 bytes AUTH)
[1607   8]         QUERY FINAL A "aba8735d2c3d241de.awsglobalaccelerator.com." from [ns-409.awsdns-51.com. 205.251.193.153 ns-1484.awsdns-57.org. ns-609.awsdns-12.net. ns-1949.awsdns-51.co.uk.]
[1607   8]         SENDING udp4: @205.251.193.153 A "aba8735d2c3d241de.awsglobalaccelerator.com." => NOERROR [2+4+1 A/N/E] (2ms, 423 bytes AUTH)
[1609   8]         final nameservers: [205.251.193.153]
[1609   8]         SENDING udp4: @205.251.193.153 A "aba8735d2c3d241de.awsglobalaccelerator.com." => NOERROR [2+4+1 A/N/E] (2ms, 423 bytes AUTH)
[1611   8]         ANSWER NOERROR for A "aba8735d2c3d241de.awsglobalaccelerator.com." with 2 records
[1611   7]        CNAME ANSWER NOERROR "aba8735d2c3d241de.awsglobalaccelerator.com." with 2 records
[1611   6]       CNAME ANSWER NOERROR "gr.aga.console-geo.eu-north-1.amazonaws.com." with 3 records
[1611   5]      CNAME ANSWER NOERROR "eu-north-1.console.cname-proxy.amazon.com." with 4 records
[1611   4]     CNAME ANSWER NOERROR "eu-north-1.console.aws.amazon.com." with 5 records
[1611   3]    CNAME ANSWER NOERROR "lbr.us.console.amazonaws.com." with 6 records
[1611   2]   CNAME ANSWER NOERROR "console.cname-proxy.amazon.com." with 7 records

;; opcode: QUERY, status: NOERROR, id: 39234
;; flags: qr aa rd; QUERY: 1, ANSWER: 8, AUTHORITY: 4, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version 0; flags:; udp: 4096

;; QUESTION SECTION:
;console.aws.amazon.com.        IN       A

;; ANSWER SECTION:
console.aws.amazon.com. 7200    IN      CNAME   console.cname-proxy.amazon.com.
console.cname-proxy.amazon.com. 60      IN      CNAME   lbr.us.console.amazonaws.com.
lbr.us.console.amazonaws.com.   60      IN      CNAME   eu-north-1.console.aws.amazon.com.
eu-north-1.console.aws.amazon.com.      7200    IN      CNAME   eu-north-1.console.cname-proxy.amazon.com.
eu-north-1.console.cname-proxy.amazon.com.      60      IN      CNAME   gr.aga.console-geo.eu-north-1.amazonaws.com.
gr.aga.console-geo.eu-north-1.amazonaws.com.    60      IN      CNAME   aba8735d2c3d241de.awsglobalaccelerator.com.
aba8735d2c3d241de.awsglobalaccelerator.com.     300     IN      A       166.117.98.246
aba8735d2c3d241de.awsglobalaccelerator.com.     300     IN      A       166.117.166.206

;; AUTHORITY SECTION:
cname-proxy.amazon.com. 60      IN      NS      ns-1313.awsdns-36.org.
cname-proxy.amazon.com. 60      IN      NS      ns-1878.awsdns-42.co.uk.
cname-proxy.amazon.com. 60      IN      NS      ns-429.awsdns-53.com.
cname-proxy.amazon.com. 60      IN      NS      ns-689.awsdns-22.net.

;; Sent 56 queries in 1.611s
;; SERVER: 192.5.6.30
;;; cache size 3, hit ratio 20.00%

Documentation

Overview

package recursive provides a minimal iterative DNS resolver with QNAME minimization using github.com/miekg/dns for wire format and transport.

Index

Constants

View Source 
const DefaultMaxTTL = 6 * time.Hour // six hours
View Source 
const DefaultMinTTL = 10 * time.Second // ten seconds
View Source 
const DefaultNXTTL = time.Hour // one hour
View Source 
const MaxQtype = 260

Variables

View Source 
var (
	// ErrInvalidCookie is returned if the DNS cookie from the server is invalid.
	ErrInvalidCookie = errors.New("invalid cookie")
	// ErrMaxDepth is returned when recursive resolving exceeds the allowed limit.
	ErrMaxDepth = fmt.Errorf("recursion depth exceeded %d", maxDepth)
	// ErrMaxSteps is returned when resolving exceeds the step limit.
	ErrMaxSteps = fmt.Errorf("resolve steps exceeded %d", maxSteps)
	// ErrNoResponse is returned when no authoritative server could be successfully queried.
	// It is equivalent to SERVFAIL.
	ErrNoResponse = errors.New("no authoritative response")

	DefaultCache          = NewCache()
	DefaultTimeout        = time.Second * 3
	DefaultDNSPort uint16 = 53
)
View Source 
var ErrExtendedErrorCode = extendedErrorCodeError(0)
View Source 
var Roots4 = []netip.Addr{
	netip.AddrFrom4([4]byte([]byte{0xaa, 0xf7, 0xaa, 0x2})),
	netip.AddrFrom4([4]byte([]byte{0xc0, 0x5, 0x5, 0xf1})),
	netip.AddrFrom4([4]byte([]byte{0xc0, 0x21, 0x4, 0xc})),
	netip.AddrFrom4([4]byte([]byte{0xc0, 0x24, 0x94, 0x11})),
	netip.AddrFrom4([4]byte([]byte{0xc0, 0x3a, 0x80, 0x1e})),
	netip.AddrFrom4([4]byte([]byte{0xc0, 0x70, 0x24, 0x4})),
	netip.AddrFrom4([4]byte([]byte{0xc0, 0xcb, 0xe6, 0xa})),
	netip.AddrFrom4([4]byte([]byte{0xc1, 0x0, 0xe, 0x81})),
	netip.AddrFrom4([4]byte([]byte{0xc6, 0x29, 0x0, 0x4})),
	netip.AddrFrom4([4]byte([]byte{0xc6, 0x61, 0xbe, 0x35})),
	netip.AddrFrom4([4]byte([]byte{0xc7, 0x7, 0x53, 0x2a})),
	netip.AddrFrom4([4]byte([]byte{0xc7, 0x7, 0x5b, 0xd})),
	netip.AddrFrom4([4]byte([]byte{0xca, 0xc, 0x1b, 0x21})),
}
View Source 
var Roots6 = []netip.Addr{
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x53})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xc})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0x12, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xd, 0xd})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0x2d, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xd})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0x2f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xf})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0x9f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x42})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x0, 0x0, 0xa8, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xe})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x3, 0xc, 0x27, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x0, 0x30})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x5, 0x3, 0xba, 0x3e, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x0, 0x30})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x7, 0xfd, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0x7, 0xfe, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x53})),
	netip.AddrFrom16([16]byte([]byte{0x20, 0x1, 0xd, 0xc3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x35})),
	netip.AddrFrom16([16]byte([]byte{0x28, 0x1, 0x1, 0xb8, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xb})),
}

Functions

func ErrorFromExtendedErrorCode added in v0.16.0 

func ErrorFromExtendedErrorCode(code uint16) (err error)

ErrorFromExtendedErrorCode returns the canonical Go error for the provided Extended Error Code. It returns ErrExtendedErrorCode if there is no known mapping.

func ExtendedErrorCodeFromError added in v0.16.0 

func ExtendedErrorCodeFromError(err error) (rcode uint16)

ExtendedErrorCodeFromError attempts to map a Go error to a DNS Extended Rcode. The function understands well-known errors from the os, io, and net packages (including their wrapper types) and returns dns.ExtendedErrorCodeOther if no mapping is known.

Types

type Cache added in v0.1.2 

type Cache struct {
	MinTTL time.Duration // always cache responses for at least this long
	MaxTTL time.Duration // never cache responses for longer than this (excepting successful NS responses)
	NXTTL  time.Duration // cache NXDOMAIN responses for this long
	// contains filtered or unexported fields
}

func NewCache added in v0.1.2 

func NewCache() *Cache

func (*Cache) Clean added in v0.1.2 

func (cache *Cache) Clean()

func (*Cache) Clear added in v0.1.4 

func (cache *Cache) Clear()

func (*Cache) DnsGet added in v0.2.0 

func (cache *Cache) DnsGet(qname string, qtype uint16) (msg *dns.Msg)

func (*Cache) DnsResolve added in v0.2.0 

func (cache *Cache) DnsResolve(ctx context.Context, qname string, qtype uint16) (msg *dns.Msg, srv netip.Addr, err error)

func (*Cache) DnsSet added in v0.2.0 

func (cache *Cache) DnsSet(msg *dns.Msg)

func (*Cache) Entries added in v0.2.0 

func (cache *Cache) Entries() (n int)

Entries returns the number of entries in the cache.

func (*Cache) HitRatio added in v0.1.2 

func (cache *Cache) HitRatio() (n float64)

HitRatio returns the hit ratio as a percentage.

type Cacher added in v0.1.4 

type Cacher interface {
	// DnsSet stores msg for the supplied question. Implementations may keep a
	// private copy, but the cached instance must have dns.Msg.Zero set to true
	// before it is returned by DnsGet.
	DnsSet(msg *dns.Msg)

	// DnsGet returns the cached dns.Msg pointer for the given qname and qtype, or
	// nil if no entry exists. The returned message MUST keep dns.Msg.Zero set to
	// true to signal it originated from cache, and callers MUST treat it as
	// immutable by copying it before applying any mutations.
	DnsGet(qname string, qtype uint16) *dns.Msg
}

type CachingResolver added in v0.2.0 

type CachingResolver interface {
	Resolver
	Cacher
}

type Recursive added in v0.1.6 

type Recursive struct {
	proxy.ContextDialer // context dialer to use
	Cacher              // cache to use for DnsResolve
	Timeout             time.Duration
	DNSPort             uint16
	// contains filtered or unexported fields
}

func New 

func New(dialer proxy.ContextDialer) *Recursive

New returns a new Recursive resolver using the given ContextDialer and has DefaultCache as it's cache.

It calls OrderRoots before returning.

func NewWithOptions 

func NewWithOptions(dialer proxy.ContextDialer, cache Cacher, roots4, roots6 []netip.Addr, rateLimiter <-chan struct{}) *Recursive

NewWithOptions returns a new Recursive resolver using the given ContextDialer and using the given Cacher as the cache when calling DnsResolve. It does not call OrderRoots.

Passing nil for dialer will use a net.Dialer. Passing nil for the roots will use the default set of roots. Passing nil for the rateLimiter means no rate limiting

func (*Recursive) DnsResolve added in v0.2.0 

func (r *Recursive) DnsResolve(ctx context.Context, qname string, qtype uint16) (msg *dns.Msg, srv netip.Addr, err error)

func (*Recursive) GetRoots added in v0.9.1 

func (r *Recursive) GetRoots() (root4, root6 []netip.Addr)

GetRoots returns the current set of root servers in use.

func (*Recursive) OrderRoots added in v0.2.0 

func (r *Recursive) OrderRoots(ctx context.Context)

func (*Recursive) OrderRootsTimeout added in v0.18.0 

func (r *Recursive) OrderRootsTimeout(ctx context.Context, cutoff time.Duration)

OrderRootsTimeout sorts the root server list by their current latency and removes those that don't respond within cutoff.

func (*Recursive) ResetCookies added in v0.5.0 

func (r *Recursive) ResetCookies()

ResetCookies generates a new DNS client cookie and clears the known DNS server cookies.

func (*Recursive) ResolveWithOptions added in v0.1.6 

func (r *Recursive) ResolveWithOptions(ctx context.Context, cache Cacher, logw io.Writer, qname string, qtype uint16) (msg *dns.Msg, origin netip.Addr, err error)

ResolveWithOptions performs iterative resolution with QNAME minimization for qname/qtype.

type Resolver 

type Resolver interface {
	DnsResolve(ctx context.Context, qname string, qtype uint16) (msg *dns.Msg, srv netip.Addr, err error)
}

Source Files

View all Source files

Directories

Path Synopsis
cmd
cli command
genhints command

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