| // Copyright Istio Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package client |
| |
| import ( |
| "net" |
| "time" |
| ) |
| |
| import ( |
| "github.com/miekg/dns" |
| ) |
| |
| type dnsProxy struct { |
| serveMux *dns.ServeMux |
| server *dns.Server |
| |
| // This is the upstream Client used to make upstream DNS queries |
| // in case the data is not in our name table. |
| upstreamClient *dns.Client |
| protocol string |
| resolver *LocalDNSServer |
| } |
| |
| func newDNSProxy(protocol, addr string, resolver *LocalDNSServer) (*dnsProxy, error) { |
| p := &dnsProxy{ |
| serveMux: dns.NewServeMux(), |
| server: &dns.Server{}, |
| upstreamClient: &dns.Client{ |
| Net: protocol, |
| DialTimeout: 5 * time.Second, |
| ReadTimeout: 5 * time.Second, |
| WriteTimeout: 5 * time.Second, |
| }, |
| protocol: protocol, |
| resolver: resolver, |
| } |
| |
| var err error |
| p.serveMux.Handle(".", p) |
| p.server.Handler = p.serveMux |
| if protocol == "udp" { |
| p.server.PacketConn, err = net.ListenPacket("udp", addr) |
| } else { |
| p.server.Listener, err = net.Listen("tcp", addr) |
| } |
| log.Infof("Starting local %s DNS server on %v", p.protocol, addr) |
| if err != nil { |
| log.Errorf("Failed to listen on %s port %s: %v", protocol, addr, err) |
| return nil, err |
| } |
| return p, nil |
| } |
| |
| func (p *dnsProxy) start() { |
| err := p.server.ActivateAndServe() |
| if err != nil { |
| log.Errorf("Local %s DNS server terminated: %v", p.protocol, err) |
| } |
| } |
| |
| func (p *dnsProxy) close() { |
| if p.server != nil { |
| if err := p.server.Shutdown(); err != nil { |
| log.Errorf("error in shutting down %s dns downstreamUDPServer :%v", p.protocol, err) |
| } |
| } |
| } |
| |
| func (p *dnsProxy) ServeDNS(w dns.ResponseWriter, req *dns.Msg) { |
| p.resolver.ServeDNS(p, w, req) |
| } |