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plugin/dns64 : add support for DNS requests over IPv4 network (#4809)

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This commit is contained in:
Ondřej Benkovský
2022-01-07 17:16:23 +01:00
committed by GitHub
parent 39a99a5bbe
commit b546031f9b
5 changed files with 106 additions and 9 deletions
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13
plugin/dns64/dns64.go
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@@ -28,13 +28,14 @@ type DNS64 struct {
Next plugin.Handler
Prefix *net.IPNet
TranslateAll bool // Not comply with 5.1.1
AllowIPv4 bool
Upstream UpstreamInt
}
// ServeDNS implements the plugin.Handler interface.
func (d *DNS64) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
// Don't proxy if we don't need to.
if !requestShouldIntercept(&request.Request{W: w, Req: r}) {
if !d.requestShouldIntercept(&request.Request{W: w, Req: r}) {
return d.Next.ServeDNS(ctx, w, r)
}
@@ -69,13 +70,13 @@ func (d *DNS64) Name() string { return "dns64" }
// requestShouldIntercept returns true if the request represents one that is eligible
// for DNS64 rewriting:
// 1. The request came in over IPv6 (not in RFC)
// 1. The request came in over IPv6 or the 'allow_ipv4' option is set
// 2. The request is of type AAAA
// 3. The request is of class INET
func requestShouldIntercept(req *request.Request) bool {
// Only intercept with this when the request came in over IPv6. This is not mentioned in the RFC.
// File an issue if you think we should translate even requests made using IPv4, or have a configuration flag
if req.Family() == 1 { // If it came in over v4, don't do anything.
func (d *DNS64) requestShouldIntercept(req *request.Request) bool {
// Make sure that request came in over IPv4 unless AllowIPv4 option is enabled.
// Translating requests without taking into consideration client (source) IP might be problematic in dual-stack networks.
if !d.AllowIPv4 && req.Family() == 1 {
return false
}