mirror of
https://github.com/safing/portmaster
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92 lines
2.9 KiB
Go
92 lines
2.9 KiB
Go
package nsutil
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import (
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"github.com/miekg/dns"
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"github.com/safing/portbase/log"
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)
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// Responder defines the interface that any block/deny reason interface
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// may implement to support sending custom DNS responses for a given reason.
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// That is, if a reason context implements the Responder interface the
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// ReplyWithDNS method will be called instead of creating the default
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// zero-ip response.
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type Responder interface {
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// ReplyWithDNS is called when a DNS response to a DNS message is
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// crafted because the request is either denied or blocked.
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ReplyWithDNS(query *dns.Msg, reason string, reasonCtx interface{}) *dns.Msg
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}
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// RRProvider defines the interface that any block/deny reason interface
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// may implement to support adding additional DNS resource records to
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// the DNS responses extra (additional) section.
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type RRProvider interface {
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// GetExtraRR is called when a DNS response to a DNS message is
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// crafted because the request is either denied or blocked.
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GetExtraRR(query *dns.Msg, reason string, reasonCtx interface{}) []dns.RR
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}
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// ResponderFunc is a convenience type to use a function
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// directly as a Responder.
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type ResponderFunc func(query *dns.Msg, reason string, reasonCtx interface{}) *dns.Msg
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// ReplyWithDNS implements the Responder interface and calls rf.
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func (rf ResponderFunc) ReplyWithDNS(query *dns.Msg, reason string, reasonCtx interface{}) *dns.Msg {
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return rf(query, reason, reasonCtx)
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}
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// ZeroIP is a ResponderFunc than replies with either 0.0.0.0 or :: for
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// each A or AAAA question respectively.
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func ZeroIP() ResponderFunc {
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return func(query *dns.Msg, _ string, _ interface{}) *dns.Msg {
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m := new(dns.Msg)
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hasErr := false
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for _, question := range query.Question {
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var rr dns.RR
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var err error
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switch question.Qtype {
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case dns.TypeA:
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rr, err = dns.NewRR(question.Name + " 0 IN A 0.0.0.0")
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case dns.TypeAAAA:
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rr, err = dns.NewRR(question.Name + " 0 IN AAAA ::")
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}
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if err != nil {
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log.Errorf("nameserver: failed to create zero-ip response for %s: %s", question.Name, err)
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hasErr = true
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} else {
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m.Answer = append(m.Answer, rr)
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}
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}
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if hasErr && len(m.Answer) == 0 {
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m.SetRcode(query, dns.RcodeServerFailure)
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} else {
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m.SetRcode(query, dns.RcodeSuccess)
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}
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return m
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}
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}
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// NxDomain returns a ResponderFunc that replies with NXDOMAIN.
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func NxDomain() ResponderFunc {
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return func(query *dns.Msg, _ string, _ interface{}) *dns.Msg {
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return new(dns.Msg).SetRcode(query, dns.RcodeNameError)
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}
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}
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// Refused returns a ResponderFunc that replies with REFUSED.
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func Refused() ResponderFunc {
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return func(query *dns.Msg, _ string, _ interface{}) *dns.Msg {
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return new(dns.Msg).SetRcode(query, dns.RcodeRefused)
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}
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}
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// ServeFail returns a ResponderFunc that replies with SERVFAIL.
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func ServeFail() ResponderFunc {
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return func(query *dns.Msg, _ string, _ interface{}) *dns.Msg {
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return new(dns.Msg).SetRcode(query, dns.RcodeServerFailure)
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}
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}
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