Memory cache implemented

README.MD

@@ -15,7 +15,13 @@ Similar as [dnsmasq](http://www.thekelleys.org.uk/dnsmasq/doc.html) ,but support
 * Cache records save in memory or redis configurable
 
 
-### Configuration
+## Install & Running
+
+
+
+
+
+## Configuration
 
 All the configuration on `godns.conf` a TOML formating config file.   
 More about Toml :[https://github.com/mojombo/toml](https://github.com/mojombo/toml)
@@ -33,5 +39,14 @@ If multi `namerserver` set at resolv.conf, the upsteam server will try in order
 
 
 
+#### hosts
+
+
+
+
+#### cache
+
+
+
 
 

cache.go

@@ -1,13 +1,144 @@
 package main
 
-type Cache struct {
-	config CacheSettings
+import (
+	"crypto/md5"
+	"encoding/json"
+	"fmt"
+	"github.com/miekg/dns"
+	"time"
+)
+
+type KeyNotFound struct {
+	key string
 }
 
-func (c *Cache) Get() {
+func (e KeyNotFound) Error() string {
+	return e.key + " " + "not found"
+}
+
+type KeyExpired struct {
+	Key string
+}
+
+func (e KeyExpired) Error() string {
+	return e.Key + " " + "expired"
+}
+
+type CacheIsFull struct {
+}
+
+func (e CacheIsFull) Error() string {
+	return "Cache is Full"
+}
+
+type SerializerError struct {
+}
+
+func (e SerializerError) Error() string {
+	return "Serializer error"
+}
+
+type Cache interface {
+	Get(string) ([]byte, error)
+	Set(string, *dns.Msg) error
+	Exists(string) bool
+	Remove()
+	Length() int
+}
+
+type MemoryCache struct {
+	backend    map[string]string
+	serializer *JsonSerializer
+	expire     time.Duration
+	maxcount   int
+}
+
+func (c *MemoryCache) Get(key string) ([]byte, error) {
+	fmt.Println(c.backend)
+	data, ok := c.backend[key]
+	if !ok {
+		return nil, KeyNotFound{key}
+	}
+	return []byte(data), nil
+
+	// mesg := new(dns.Msg)
+	// if err := c.serializer.Loads([]byte(data), &mesg); err != nil {
+	// 	fmt.Println(err)
+	// 	return nil, SerializerError{}
+	// }
+	// return mesg, nil
 
 }
 
-func (c *Cache) Set() {
+func (c *MemoryCache) Set(key string, mesg *dns.Msg) error {
+	if c.Full() && !c.Exists(key) {
+		return CacheIsFull{}
+	}
+	// data, err := c.serializer.Dumps(mesg)
+
+	// if err != nil {
+	// 	return SerializerError{}
+	// }
+
+	c.backend[key] = mesg.String()
+	return nil
+}
+
+func (c *MemoryCache) Remove() {
+
+}
+
+func (c *MemoryCache) Exists(key string) bool {
+	_, ok := c.backend[key]
+	return ok
+}
+
+func (c *MemoryCache) Length() int {
+	return len(c.backend)
+}
+
+func (c *MemoryCache) Full() bool {
+	// if maxcount is zero. the cache will never be full.
+	if c.maxcount == 0 {
+		return false
+	}
+	return c.Length() >= c.maxcount
+}
+
+// type RedisCache struct{
+// backend redis.client
+// }
+
+// func (c *RedisCache) Get(key string) {
+
+// }
+
+// func (c *RedisCache) Set() {
+
+// }
+
+// func (c &RedisCache) Remove(){
+
+// }
+
+func KeyGen(q Question) string {
+	h := md5.New()
+	h.Write([]byte(q.String()))
+	x := h.Sum(nil)
+	key := fmt.Sprintf("%x", x)
+	return key
+}
+
+type JsonSerializer struct {
+}
+
+func (*JsonSerializer) Dumps(mesg *dns.Msg) (encoded []byte, err error) {
+	encoded, err = json.Marshal(mesg)
+	return
+}
+
+func (*JsonSerializer) Loads(data []byte, mesg **dns.Msg) error {
+	err := json.Unmarshal(data, mesg)
+	return err
 
 }

handler.go

@@ -3,12 +3,22 @@ package main
 import (
 	"github.com/miekg/dns"
 	// "log"
-	// "fmt"
+	"fmt"
 )
 
+type Question struct {
+	qname  string
+	qtype  string
+	qclass string
+}
+
+func (q *Question) String() string {
+	return q.qname + " " + q.qclass + " " + q.qtype
+}
+
 type GODNSHandler struct {
 	resolver *Resolver
-	cache    *Cache
+	cache    Cache
 }
 
 func NewHandler() *GODNSHandler {
@@ -16,6 +26,8 @@ func NewHandler() *GODNSHandler {
 	var (
 		clientConfig *dns.ClientConfig
 		cacheConfig  CacheSettings
+		resolver     *Resolver
+		cache        Cache
 	)
 
 	resolvConfig := settings.ResolvConfig
@@ -26,11 +38,28 @@ func NewHandler() *GODNSHandler {
 		panic(err)
 	}
 	clientConfig.Timeout = resolvConfig.Timeout
-	resolver := &Resolver{clientConfig}
+	resolver = &Resolver{clientConfig}
 
 	cacheConfig = settings.Cache
-	cache := &Cache{cacheConfig}
-
+	switch cacheConfig.Backend {
+	case "memory":
+		cache = &MemoryCache{
+			backend:    make(map[string]string),
+			serializer: new(JsonSerializer),
+			expire:     cacheConfig.Expire,
+			maxcount:   cacheConfig.Maxcount,
+		}
+	case "redis":
+		cache = &MemoryCache{
+			backend:    make(map[string]string),
+			serializer: new(JsonSerializer),
+			expire:     cacheConfig.Expire,
+			maxcount:   cacheConfig.Maxcount,
+		}
+	default:
+		logger.Printf("Invalid cache backend %s", cacheConfig.Backend)
+		panic("Invalid cache backend")
+	}
 	return &GODNSHandler{resolver, cache}
 }
 
@@ -41,6 +70,22 @@ func (h *GODNSHandler) do(net string, w dns.ResponseWriter, req *dns.Msg) {
 
 	Debug("Question:　%s", Q.String())
 
+	key := KeyGen(Q)
+	fmt.Println(key)
+	// Only query cache when qtype == 'A' , qclass == 'IN'
+	if q.Qtype == dns.TypeA && q.Qclass == dns.ClassINET {
+		mesg, err := h.cache.Get(key)
+		if err != nil {
+			Debug("%s didn't hit cache: %s", Q.String(), err)
+		} else {
+			Debug("%s hit cache", Q.String())
+			fmt.Println(string(mesg))
+			w.Write(mesg)
+			return
+		}
+
+	}
+
 	mesg, err := h.resolver.Lookup(net, req)
 
 	if err != nil {
@@ -51,6 +96,16 @@ func (h *GODNSHandler) do(net string, w dns.ResponseWriter, req *dns.Msg) {
 
 	w.WriteMsg(mesg)
 
+	if q.Qtype == dns.TypeA && q.Qclass == dns.ClassINET {
+		err = h.cache.Set(key, mesg)
+
+		if err != nil {
+			Debug("Set %s cache failed: %s", Q.String(), err.Error())
+		}
+
+		Debug("Insert %s into cache", Q.String())
+	}
+
 }
 
 func (h *GODNSHandler) DoTCP(w dns.ResponseWriter, req *dns.Msg) {
@@ -60,13 +115,3 @@ func (h *GODNSHandler) DoTCP(w dns.ResponseWriter, req *dns.Msg) {
 func (h *GODNSHandler) DoUDP(w dns.ResponseWriter, req *dns.Msg) {
 	h.do("udp", w, req)
 }
-
-type Question struct {
-	qname  string
-	qtype  string
-	qclass string
-}
-
-func (q *Question) String() string {
-	return q.qname + " " + q.qclass + " " + q.qtype
-}

settings.go

@@ -46,7 +46,7 @@ type LogSettings struct {
 type CacheSettings struct {
 	Backend  string
 	Expire   time.Duration
-	Maxcount uint32
+	Maxcount int
 }
 
 func init() {