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net/dns/{publicdns,resolver}: add start of Control D support

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Updates #7946

[@bradfitz fixed up version of #8417]

Change-Id: I1dbf6fa8d525b25c0d7ad5c559a7f937c3cd142a
Signed-off-by: alexelisenko <39712468+alexelisenko@users.noreply.github.com>
Signed-off-by: Alex Paguis <alex@windscribe.com>
This commit is contained in:
alexelisenko 2023-06-22 20:47:36 -04:00 committed by Brad Fitzpatrick
parent aa084a29c6
commit fe22032fb3
No known key found for this signature in database
3 changed files with 109 additions and 5 deletions
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86
net/dns/publicdns/publicdns.go
View File

@ -7,10 +7,13 @@
import (
"bytes"
"encoding/binary"
"encoding/hex"
"fmt"
"math/big"
"net/netip"
"sort"
"strconv"
"strings"
"sync"
)
@ -23,6 +26,11 @@
var dohIPsOfBase = map[string][]netip.Addr{}
var populateOnce sync.Once
const (
nextDNSBase = "https://dns.nextdns.io/"
controlDBase = "https://dns.controld.com/"
)
// DoHEndpointFromIP returns the DNS-over-HTTPS base URL for a given IP
// and whether it's DoH-only (not speaking DNS on port 53).
//
@ -39,14 +47,21 @@ func DoHEndpointFromIP(ip netip.Addr) (dohBase string, dohOnly bool, ok bool) {
if nextDNSv6RangeA.Contains(ip) || nextDNSv6RangeB.Contains(ip) {
a := ip.As16()
var sb strings.Builder
const base = "https://dns.nextdns.io/"
sb.Grow(len(base) + 12)
sb.WriteString(base)
sb.Grow(len(nextDNSBase) + 12)
sb.WriteString(nextDNSBase)
for _, b := range bytes.TrimLeft(a[4:], "\x00") {
fmt.Fprintf(&sb, "%02x", b)
}
return sb.String(), true, true
}
// Control D DoH URLs are of the form "https://dns.controld.com/8yezwenugs"
// where the path component is represented by 8 bytes (7-14) of the IPv6 address in base36
if controlDv6RangeA.Contains(ip) || controlDv6RangeB.Contains(ip) {
path := big.NewInt(0).SetBytes(ip.AsSlice()[6:14]).Text(36)
return controlDBase + path, true, true
}
return "", false, false
}
@ -80,7 +95,7 @@ func DoHIPsOfBase(dohBase string) []netip.Addr {
if s := dohIPsOfBase[dohBase]; len(s) > 0 {
return s
}
if hexStr, ok := strings.CutPrefix(dohBase, "https://dns.nextdns.io/"); ok {
if hexStr, ok := strings.CutPrefix(dohBase, nextDNSBase); ok {
// The path is of the form /<profile-hex>[/<hostname>/<model>/<device id>...]
// or /<profile-hex>?<query params>
// but only the <profile-hex> is required. Ignore the rest:
@ -106,6 +121,14 @@ func DoHIPsOfBase(dohBase string) []netip.Addr {
}
}
}
if pathStr, ok := strings.CutPrefix(dohBase, controlDBase); ok {
return []netip.Addr{
controlDv4One,
controlDv4Two,
controlDv6Gen(nextDNSv6RangeA.Addr(), pathStr),
controlDv6Gen(nextDNSv6RangeB.Addr(), pathStr),
}
}
return nil
}
@ -213,6 +236,36 @@ func populate() {
// Wikimedia
addDoH(wikimediaDNSv4, "https://wikimedia-dns.org/dns-query")
addDoH(wikimediaDNSv6, "https://wikimedia-dns.org/dns-query")
// Control D
addDoH("76.76.2.0", "https://freedns.controld.com/p0")
addDoH("76.76.10.0", "https://freedns.controld.com/p0")
addDoH("2606:1a40::", "https://freedns.controld.com/p0")
addDoH("2606:1a40:1::", "https://freedns.controld.com/p0")
// Control D -Malware
addDoH("76.76.2.1", "https://freedns.controld.com/p1")
addDoH("76.76.10.1", "https://freedns.controld.com/p1")
addDoH("2606:1a40::1", "https://freedns.controld.com/p1")
addDoH("2606:1a40:1::1", "https://freedns.controld.com/p1")
// Control D -Malware + Ads
addDoH("76.76.2.2", "https://freedns.controld.com/p2")
addDoH("76.76.10.2", "https://freedns.controld.com/p2")
addDoH("2606:1a40::2", "https://freedns.controld.com/p2")
addDoH("2606:1a40:1::2", "https://freedns.controld.com/p2")
// Control D -Malware + Ads + Social
addDoH("76.76.2.3", "https://freedns.controld.com/p3")
addDoH("76.76.10.3", "https://freedns.controld.com/p3")
addDoH("2606:1a40::3", "https://freedns.controld.com/p3")
addDoH("2606:1a40:1::3", "https://freedns.controld.com/p3")
// Control D -Malware + Ads + Adult
addDoH("76.76.2.4", "https://freedns.controld.com/family")
addDoH("76.76.10.4", "https://freedns.controld.com/family")
addDoH("2606:1a40::4", "https://freedns.controld.com/family")
addDoH("2606:1a40:1::4", "https://freedns.controld.com/family")
}
var (
@ -239,6 +292,13 @@ func populate() {
// Wikimedia DNS server IPs (anycast)
wikimediaDNSv4Addr = netip.MustParseAddr(wikimediaDNSv4)
wikimediaDNSv6Addr = netip.MustParseAddr(wikimediaDNSv6)
// The Control D IPv6 ranges (primary and secondary). The customer ID is
// encoded in the ipv6 address is used (in base 36 form) as the DoH query
controlDv6RangeA = netip.MustParsePrefix("2606:1a40::/48")
controlDv6RangeB = netip.MustParsePrefix("2606:1a40:1::/48")
controlDv4One = netip.MustParseAddr("76.76.2.22")
controlDv4Two = netip.MustParseAddr("76.76.10.22")
)
// nextDNSv6Gen generates a NextDNS IPv6 address from the upper 8 bytes in the
@ -252,10 +312,26 @@ func nextDNSv6Gen(ip netip.Addr, id []byte) netip.Addr {
return netip.AddrFrom16(a)
}
// controlDv6Gen generates a Control D IPv6 address from provided ip and id.
//
// The id is taken from the DoH query path component and represents a unique resolver configuration.
// e.g. https://dns.controld.com/hyq3ipr2ct
func controlDv6Gen(ip netip.Addr, id string) netip.Addr {
b := make([]byte, 8)
decoded, _ := strconv.ParseUint(id, 36, 64)
binary.BigEndian.PutUint64(b, decoded)
a := ip.AsSlice()
copy(a[6:14], b)
addr, _ := netip.AddrFromSlice(a)
return addr
}
// IPIsDoHOnlyServer reports whether ip is a DNS server that should only use
// DNS-over-HTTPS (not regular port 53 DNS).
func IPIsDoHOnlyServer(ip netip.Addr) bool {
return nextDNSv6RangeA.Contains(ip) || nextDNSv6RangeB.Contains(ip) ||
nextDNSv4RangeA.Contains(ip) || nextDNSv4RangeB.Contains(ip) ||
ip == wikimediaDNSv4Addr || ip == wikimediaDNSv6Addr
ip == wikimediaDNSv4Addr || ip == wikimediaDNSv6Addr ||
controlDv6RangeA.Contains(ip) || controlDv6RangeB.Contains(ip) ||
ip == controlDv4One || ip == controlDv4Two
}

18
net/dns/publicdns/publicdns_test.go
View File

@ -116,6 +116,24 @@ func TestDoHIPsOfBase(t *testing.T) {
"2a07:a8c1::c3:a884",
),
},
{
base: "https://dns.controld.com/hyq3ipr2ct",
want: ips(
"76.76.2.22",
"76.76.10.22",
"2a07:a8c0:0:6:7b5b:5949:35ad:0",
"2a07:a8c1:0:6:7b5b:5949:35ad:0",
),
},
{
base: "https://dns.controld.com/112233445566778899aabbcc",
want: ips(
"76.76.2.22",
"76.76.10.22",
"2a07:a8c0:0:ffff:ffff:ffff:ffff:0",
"2a07:a8c1:0:ffff:ffff:ffff:ffff:0",
),
},
}
for _, tt := range tests {
got := DoHIPsOfBase(tt.base)

10
net/dns/resolver/forwarder_test.go
View File

@ -101,6 +101,16 @@ func TestResolversWithDelays(t *testing.T) {
in: q("https://dns.nextdns.io/c3a884"),
want: o("https://dns.nextdns.io/c3a884"),
},
{
name: "controld-ipv6-expand",
in: q("2606:1a40:0:6:7b5b:5949:35ad:0"),
want: o("https://dns.controld.com/hyq3ipr2ct"),
},
{
name: "controld-doh-input",
in: q("https://dns.controld.com/hyq3ipr2ct"),
want: o("https://dns.controld.com/hyq3ipr2ct"),
},
}
for _, tt := range tests {