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DNS DoH: Use EDNS0 with 100-300 padding by default (body padding)

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https://github.com/XTLS/Xray-core/pull/4516#issuecomment-2744093003
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RPRX 2025-03-21 20:13:09 +00:00 • committed by GitHub
parent b585b26f29
commit 607c2a6d31
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6 changed files with 51 additions and 39 deletions
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78
app/dns/dnscommon.go
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@ -68,49 +68,59 @@ type dnsRequest struct {
msg *dnsmessage.Message
}
func genEDNS0Options(clientIP net.IP) *dnsmessage.Resource {
if len(clientIP) == 0 {
func genEDNS0Options(clientIP net.IP, padding int) *dnsmessage.Resource {
if len(clientIP) == 0 && padding == 0 {
return nil
}
var netmask int
var family uint16
if len(clientIP) == 4 {
family = 1
netmask = 24 // 24 for IPV4, 96 for IPv6
} else {
family = 2
netmask = 96
}
b := make([]byte, 4)
binary.BigEndian.PutUint16(b[0:], family)
b[2] = byte(netmask)
b[3] = 0
switch family {
case 1:
ip := clientIP.To4().Mask(net.CIDRMask(netmask, net.IPv4len*8))
needLength := (netmask + 8 - 1) / 8 // division rounding up
b = append(b, ip[:needLength]...)
case 2:
ip := clientIP.Mask(net.CIDRMask(netmask, net.IPv6len*8))
needLength := (netmask + 8 - 1) / 8 // division rounding up
b = append(b, ip[:needLength]...)
}
const EDNS0SUBNET = 0x08
const EDNS0SUBNET = 0x8
const EDNS0PADDING = 0xc
opt := new(dnsmessage.Resource)
common.Must(opt.Header.SetEDNS0(1350, 0xfe00, true))
body := dnsmessage.OPTResource{}
opt.Body = &body
opt.Body = &dnsmessage.OPTResource{
Options: []dnsmessage.Option{
{
if len(clientIP) != 0 {
var netmask int
var family uint16
if len(clientIP) == 4 {
family = 1
netmask = 24 // 24 for IPV4, 96 for IPv6
} else {
family = 2
netmask = 96
}
b := make([]byte, 4)
binary.BigEndian.PutUint16(b[0:], family)
b[2] = byte(netmask)
b[3] = 0
switch family {
case 1:
ip := clientIP.To4().Mask(net.CIDRMask(netmask, net.IPv4len*8))
needLength := (netmask + 8 - 1) / 8 // division rounding up
b = append(b, ip[:needLength]...)
case 2:
ip := clientIP.Mask(net.CIDRMask(netmask, net.IPv6len*8))
needLength := (netmask + 8 - 1) / 8 // division rounding up
b = append(b, ip[:needLength]...)
}
body.Options = append(body.Options,
dnsmessage.Option{
Code: EDNS0SUBNET,
Data: b,
},
},
})
}
if padding != 0 {
body.Options = append(body.Options,
dnsmessage.Option{
Code: EDNS0PADDING,
Data: make([]byte, padding),
})
}
return opt