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package SessionUtil
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import (
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"crypto/rand"
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"encoding/base64"
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"fmt"
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"io"
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"net/http"
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"net/url"
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"sync"
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"time"
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)
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//session存储方式接口
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type Provider interface {
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//初始化一个session，sid根据需要生成后传入
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SessionInit(sid string) (Session, error)
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//根据sid,获取session
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SessionRead(sid string) (Session, error)
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//销毁session
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SessionDestroy(sid string) error
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//回收
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SessionGC(maxLifeTime int64)
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}
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//Session操作接口
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type Session interface {
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Set(key, value interface{}) error
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Get(key interface{}) interface{}
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Delete(ket interface{}) error
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SessionID() string
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}
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type Manager struct {
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cookieName string
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lock sync.Mutex //互斥锁
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provider Provider //存储session方式
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maxLifeTime int64 //有效期
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}
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//实例化一个session管理器
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func NewSessionManager(provideName, cookieName string, maxLifeTime int64) (*Manager, error) {
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provide, ok := provides[provideName]
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if !ok {
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return nil, fmt.Errorf("session: unknown provide %q ", provideName)
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}
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return &Manager{cookieName: cookieName, provider: provide, maxLifeTime: maxLifeTime}, nil
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}
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//注册 由实现Provider接口的结构体调用
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func Register(name string, provide Provider) {
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if provide == nil {
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panic("session: Register provide is nil")
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}
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if _, ok := provides[name]; ok {
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panic("session: Register called twice for provide " + name)
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}
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provides[name] = provide
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}
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var provides = make(map[string]Provider)
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//生成sessionId
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func (manager *Manager) sessionId() string {
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b := make([]byte, 32)
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if _, err := io.ReadFull(rand.Reader, b); err != nil {
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return ""
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}
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//加密
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return base64.URLEncoding.EncodeToString(b)
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}
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//判断当前请求的cookie中是否存在有效的session，存在返回，否则创建
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func (manager *Manager) SessionStart(w http.ResponseWriter, r *http.Request) (session Session) {
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manager.lock.Lock() //加锁
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defer manager.lock.Unlock()
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cookie, err := r.Cookie(manager.cookieName)
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if err != nil || cookie.Value == "" {
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//创建一个
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sid := manager.sessionId()
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session, _ = manager.provider.SessionInit(sid)
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cookie := http.Cookie{
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Name: manager.cookieName,
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Value: url.QueryEscape(sid), //转义特殊符号@#￥%+*-等
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Path: "/",
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HttpOnly: true,
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MaxAge: int(manager.maxLifeTime),
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Expires: time.Now().Add(time.Duration(manager.maxLifeTime)),
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//MaxAge和Expires都可以设置cookie持久化时的过期时长，Expires是老式的过期方法，
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// 如果可以，应该使用MaxAge设置过期时间，但有些老版本的浏览器不支持MaxAge。
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// 如果要支持所有浏览器，要么使用Expires，要么同时使用MaxAge和Expires。
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}
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http.SetCookie(w, &cookie)
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} else {
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sid, _ := url.QueryUnescape(cookie.Value) //反转义特殊符号
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session, _ = manager.provider.SessionRead(sid)
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}
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return session
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}
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//销毁session 同时删除cookie
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func (manager *Manager) SessionDestroy(w http.ResponseWriter, r *http.Request) {
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cookie, err := r.Cookie(manager.cookieName)
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if err != nil || cookie.Value == "" {
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return
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} else {
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manager.lock.Lock()
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defer manager.lock.Unlock()
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sid, _ := url.QueryUnescape(cookie.Value)
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manager.provider.SessionDestroy(sid)
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expiration := time.Now()
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cookie := http.Cookie{
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Name: manager.cookieName,
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Path: "/",
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HttpOnly: true,
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Expires: expiration,
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MaxAge: -1}
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http.SetCookie(w, &cookie)
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}
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}
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func (manager *Manager) GC() {
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manager.lock.Lock()
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defer manager.lock.Unlock()
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manager.provider.SessionGC(manager.maxLifeTime)
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time.AfterFunc(time.Duration(manager.maxLifeTime), func() { manager.GC() })
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} |
