8c4b338257
FIXME: serialization needs work.
220 lines
4.8 KiB
Go
220 lines
4.8 KiB
Go
package main
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import (
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"net"
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"time"
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"github.com/miekg/dns"
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)
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const (
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notIPQuery = 0
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_IP4Query = 4
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_IP6Query = 6
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)
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type Question struct {
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qname string
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qtype string
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qclass string
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}
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func (q *Question) String() string {
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return q.qname + " " + q.qclass + " " + q.qtype
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}
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type GODNSHandler struct {
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resolver *Resolver
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cache, negCache Cache
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hosts Hosts
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}
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func NewHandler() *GODNSHandler {
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var (
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clientConfig *dns.ClientConfig
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cacheConfig CacheSettings
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resolver *Resolver
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cache, negCache Cache
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)
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resolvConfig := settings.ResolvConfig
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clientConfig, err := dns.ClientConfigFromFile(resolvConfig.ResolvFile)
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if err != nil {
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logger.Warn(":%s is not a valid resolv.conf file\n", resolvConfig.ResolvFile)
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logger.Error(err.Error())
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panic(err)
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}
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clientConfig.Timeout = resolvConfig.Timeout
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resolver = &Resolver{clientConfig}
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cacheConfig = settings.Cache
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switch cacheConfig.Backend {
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case "memory":
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cache = &MemoryCache{
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Backend: make(map[string]Mesg, cacheConfig.Maxcount),
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Expire: time.Duration(cacheConfig.Expire) * time.Second,
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Maxcount: cacheConfig.Maxcount,
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}
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negCache = &MemoryCache{
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Backend: make(map[string]Mesg),
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Expire: time.Duration(cacheConfig.Expire) * time.Second / 2,
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Maxcount: cacheConfig.Maxcount,
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}
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case "memcache":
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cache = NewMemcachedCache(
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settings.Memcache.Servers,
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int32(cacheConfig.Expire))
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negCache = NewMemcachedCache(
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settings.Memcache.Servers,
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int32(cacheConfig.Expire/2))
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case "redis":
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// cache = &MemoryCache{
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// Backend: make(map[string]*dns.Msg),
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// Expire: time.Duration(cacheConfig.Expire) * time.Second,
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// Serializer: new(JsonSerializer),
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// Maxcount: cacheConfig.Maxcount,
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// }
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panic("Redis cache backend not implement yet")
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default:
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logger.Error("Invalid cache backend %s", cacheConfig.Backend)
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panic("Invalid cache backend")
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}
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var hosts Hosts
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if settings.Hosts.Enable {
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hosts = NewHosts(settings.Hosts, settings.Redis)
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}
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return &GODNSHandler{resolver, cache, negCache, hosts}
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}
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func (h *GODNSHandler) do(Net string, w dns.ResponseWriter, req *dns.Msg) {
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q := req.Question[0]
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Q := Question{UnFqdn(q.Name), dns.TypeToString[q.Qtype], dns.ClassToString[q.Qclass]}
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var remote net.IP
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if Net == "tcp" {
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remote = w.RemoteAddr().(*net.TCPAddr).IP
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} else {
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remote = w.RemoteAddr().(*net.UDPAddr).IP
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}
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logger.Info("%s lookup %s", remote, Q.String())
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IPQuery := h.isIPQuery(q)
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// Query hosts
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if settings.Hosts.Enable && IPQuery > 0 {
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if ips, ok := h.hosts.Get(Q.qname, IPQuery); ok {
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m := new(dns.Msg)
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m.SetReply(req)
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switch IPQuery {
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case _IP4Query:
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rr_header := dns.RR_Header{
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Name: q.Name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: settings.Hosts.TTL,
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}
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for _, ip := range ips {
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a := &dns.A{rr_header, ip}
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m.Answer = append(m.Answer, a)
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}
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case _IP6Query:
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rr_header := dns.RR_Header{
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Name: q.Name,
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Rrtype: dns.TypeAAAA,
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Class: dns.ClassINET,
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Ttl: settings.Hosts.TTL,
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}
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for _, ip := range ips {
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aaaa := &dns.AAAA{rr_header, ip}
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m.Answer = append(m.Answer, aaaa)
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}
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}
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w.WriteMsg(m)
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logger.Debug("%s found in hosts file", Q.qname)
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return
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} else {
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logger.Debug("%s didn't found in hosts file", Q.qname)
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}
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}
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// Only query cache when qtype == 'A'|'AAAA' , qclass == 'IN'
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key := KeyGen(Q)
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if IPQuery > 0 {
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mesg, err := h.cache.Get(key)
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if err != nil {
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if mesg, err = h.negCache.Get(key); err != nil {
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logger.Debug("%s didn't hit cache", Q.String())
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} else {
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logger.Debug("%s hit negative cache", Q.String())
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dns.HandleFailed(w, req)
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return
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}
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} else {
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logger.Debug("%s hit cache", Q.String())
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// we need this copy against concurrent modification of Id
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msg := *mesg
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msg.Id = req.Id
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w.WriteMsg(&msg)
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return
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}
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}
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mesg, err := h.resolver.Lookup(Net, req)
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if err != nil {
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logger.Warn("Resolve query error %s", err)
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dns.HandleFailed(w, req)
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// cache the failure, too!
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if err = h.negCache.Set(key, nil); err != nil {
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logger.Warn("Set %s negative cache failed: %v", Q.String(), err)
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}
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return
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}
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w.WriteMsg(mesg)
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if IPQuery > 0 && len(mesg.Answer) > 0 {
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err = h.cache.Set(key, mesg)
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if err != nil {
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logger.Warn("Set %s cache failed: %s", Q.String(), err.Error())
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}
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logger.Debug("Insert %s into cache", Q.String())
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}
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}
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func (h *GODNSHandler) DoTCP(w dns.ResponseWriter, req *dns.Msg) {
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h.do("tcp", w, req)
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}
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func (h *GODNSHandler) DoUDP(w dns.ResponseWriter, req *dns.Msg) {
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h.do("udp", w, req)
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}
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func (h *GODNSHandler) isIPQuery(q dns.Question) int {
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if q.Qclass != dns.ClassINET {
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return notIPQuery
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}
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switch q.Qtype {
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case dns.TypeA:
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return _IP4Query
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case dns.TypeAAAA:
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return _IP6Query
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default:
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return notIPQuery
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}
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}
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func UnFqdn(s string) string {
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if dns.IsFqdn(s) {
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return s[:len(s)-1]
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}
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return s
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}
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