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+ dnsforward: use Rewrites table

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This commit is contained in:
Simon Zolin
2019-07-29 11:37:16 +03:00
parent 9857024c5d
commit 1bb6638db7
2 changed files with 143 additions and 4 deletions
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70
dnsforward/dnsforward.go
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@@ -453,11 +453,31 @@ func (s *Server) handleDNSRequest(p *proxy.Proxy, d *proxy.DNSContext) error {
}
if d.Res == nil {
answer := []dns.RR{}
originalQuestion := d.Req.Question[0]
if res.Reason == dnsfilter.ReasonRewrite && len(res.CanonName) != 0 {
answer = append(answer, s.genCNAMEAnswer(d.Req, res.CanonName))
// resolve canonical name, not the original host name
d.Req.Question[0].Name = dns.Fqdn(res.CanonName)
}
// request was not filtered so let it be processed further
err = p.Resolve(d)
if err != nil {
return err
}
if res.Reason == dnsfilter.ReasonRewrite && len(res.CanonName) != 0 {
d.Req.Question[0] = originalQuestion
d.Res.Question[0] = originalQuestion
if len(d.Res.Answer) != 0 {
answer = append(answer, d.Res.Answer...) // host -> IP
d.Res.Answer = answer
}
}
}
shouldLog := true
@@ -485,8 +505,10 @@ func (s *Server) handleDNSRequest(p *proxy.Proxy, d *proxy.DNSContext) error {
// filterDNSRequest applies the dnsFilter and sets d.Res if the request was filtered
func (s *Server) filterDNSRequest(d *proxy.DNSContext) (*dnsfilter.Result, error) {
msg := d.Req
host := strings.TrimSuffix(msg.Question[0].Name, ".")
var res dnsfilter.Result
req := d.Req
host := strings.TrimSuffix(req.Question[0].Name, ".")
origHost := host
s.RLock()
protectionEnabled := s.conf.ProtectionEnabled
@@ -497,7 +519,10 @@ func (s *Server) filterDNSRequest(d *proxy.DNSContext) (*dnsfilter.Result, error
return nil, nil
}
var res dnsfilter.Result
if host != origHost {
log.Debug("Rewrite: not supported: CNAME for %s is %s", origHost, host)
}
var err error
clientAddr := ""
@@ -508,9 +533,35 @@ func (s *Server) filterDNSRequest(d *proxy.DNSContext) (*dnsfilter.Result, error
if err != nil {
// Return immediately if there's an error
return nil, errorx.Decorate(err, "dnsfilter failed to check host '%s'", host)
} else if res.IsFiltered {
// log.Tracef("Host %s is filtered, reason - '%s', matched rule: '%s'", host, res.Reason, res.Rule)
d.Res = s.genDNSFilterMessage(d, &res)
} else if res.Reason == dnsfilter.ReasonRewrite && len(res.IPList) != 0 {
resp := dns.Msg{}
resp.SetReply(req)
name := host
if len(res.CanonName) != 0 {
resp.Answer = append(resp.Answer, s.genCNAMEAnswer(req, res.CanonName))
name = res.CanonName
}
for _, ip := range res.IPList {
if req.Question[0].Qtype == dns.TypeA {
a := s.genAAnswer(req, ip)
a.Hdr.Name = dns.Fqdn(name)
resp.Answer = append(resp.Answer, a)
} else if req.Question[0].Qtype == dns.TypeAAAA {
a := s.genAAAAAnswer(req, res.IP)
a.Hdr.Name = dns.Fqdn(name)
resp.Answer = append(resp.Answer, a)
}
}
d.Res = &resp
}
return &res, err
@@ -644,6 +695,19 @@ func (s *Server) genBlockedHost(request *dns.Msg, newAddr string, d *proxy.DNSCo
return &resp
}
// Make a CNAME response
func (s *Server) genCNAMEAnswer(req *dns.Msg, cname string) *dns.CNAME {
answer := new(dns.CNAME)
answer.Hdr = dns.RR_Header{
Name: req.Question[0].Name,
Rrtype: dns.TypeCNAME,
Ttl: s.conf.BlockedResponseTTL,
Class: dns.ClassINET,
}
answer.Target = dns.Fqdn(cname)
return answer
}
func (s *Server) genNXDomain(request *dns.Msg) *dns.Msg {
resp := dns.Msg{}
resp.SetRcode(request, dns.RcodeNameError)