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Resolve into a stub page when blocked by parental or safebrowsing. 

Closes #475.
This commit is contained in:
Eugene Bujak 2018-12-11 15:02:23 +03:00
parent 5c4ec62d96
commit 1c89e1df32
1 changed files with 52 additions and 1 deletions
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53
dnsforward/dnsforward.go
View File

@ -38,6 +38,11 @@ type Server struct {
ServerConfig
}
const (
safeBrowsingBlockHost = "standard-block.dns.adguard.com"
parentalBlockHost = "family-block.dns.adguard.com"
)
// uncomment this block to have tracing of locks
/*
func (s *Server) Lock() {
@ -426,6 +431,9 @@ func (s *Server) handlePacketInternal(msg *dns.Msg, addr net.Addr, conn *net.UDP
return s.genNotImpl(msg), nil, nil, nil
}
// we need upstream to resolve A records
upstream := s.chooseUpstream()
host := strings.TrimSuffix(msg.Question[0].Name, ".")
// use dnsfilter before cache -- changed settings or filters would require cache invalidation otherwise
var res dnsfilter.Result
@ -437,6 +445,12 @@ func (s *Server) handlePacketInternal(msg *dns.Msg, addr net.Addr, conn *net.UDP
return s.genServerFailure(msg), &res, nil, err
} else if res.IsFiltered {
log.Printf("Host %s is filtered, reason - '%s', matched rule: '%s'", host, res.Reason, res.Rule)
switch res.Reason {
case dnsfilter.FilteredSafeBrowsing:
return s.genArecord(msg, safeBrowsingBlockHost, upstream), &res, nil, nil
case dnsfilter.FilteredParental:
return s.genArecord(msg, parentalBlockHost, upstream), &res, nil, nil
}
return s.genNXDomain(msg), &res, nil, nil
}
}
@ -449,7 +463,6 @@ func (s *Server) handlePacketInternal(msg *dns.Msg, addr net.Addr, conn *net.UDP
}
// TODO: replace with single-socket implementation
upstream := s.chooseUpstream()
reply, err := upstream.Exchange(msg)
if err != nil {
log.Printf("talking to upstream failed for host '%s': %s", host, err)
@ -563,6 +576,44 @@ func (s *Server) genNotImpl(request *dns.Msg) *dns.Msg {
return &resp
}
func (s *Server) genArecord(request *dns.Msg, newAddr string, upstream Upstream) *dns.Msg {
addr := net.ParseIP(newAddr)
if addr != nil {
// this is an IP address, return it
resp := dns.Msg{}
resp.SetReply(request)
answer, err := dns.NewRR(fmt.Sprintf("%s %d A %s", request.Question[0].Name, s.BlockedResponseTTL, newAddr))
if err != nil {
log.Printf("Couldn't generate A record for up replacement host '%s': %s", newAddr, err)
return s.genServerFailure(request)
}
resp.Answer = append(resp.Answer, answer)
return &resp
}
// look up the hostname, TODO: cache
replReq := dns.Msg{}
replReq.SetQuestion(dns.Fqdn(newAddr), request.Question[0].Qtype)
replReq.RecursionDesired = true
reply, err := upstream.Exchange(&replReq)
if err != nil {
log.Printf("Couldn't look up replacement host '%s' on upstream %s: %s", newAddr, upstream.Address(), err)
return s.genServerFailure(request)
}
resp := dns.Msg{}
resp.SetReply(request)
resp.Authoritative, resp.RecursionAvailable = true, true
if reply != nil {
for _, answer := range reply.Answer {
answer.Header().Name = request.Question[0].Name
resp.Answer = append(resp.Answer, answer)
}
}
return &resp
}
func (s *Server) genNXDomain(request *dns.Msg) *dns.Msg {
resp := dns.Msg{}
resp.SetRcode(request, dns.RcodeNameError)