build-web-application-with-golang/en/14.4.md

14.4 User validation

In the process of developping web applications, user authentication is a problem which developers frequently encounter. User login, registration and logout, among other operations, as well as general authentication can also divided into three parts:

• HTTP Basic, and HTTP Digest Authentication
• Third Party Authentication Integration: QQ, micro-blogging, watercress, OPENID, Google, GitHub, Facebook and twitter, etc.
• Custom user login, registration, logout, are generally based on sessions and cookie authentication

Beego does not natively provide support for any of these three things, however you can easily make use of existing third party open source libraries to implement them. The first two authentication solutions are on Beego's roadmap to eventually be integrated.

HTTP basic and digest authentication

Both HTTP basic and digest authentication are relatively simple techniques commonly used by web applications. There are already many open source third-party libraries which support these two authentication methods, such as:

github.com/abbot/go-http-auth

The following code demonstrates how to use this library to implement authentication in a Beego application:

package controllers

import (
	"github.com/abbot/go-http-auth"
	"github.com/astaxie/beego"
)

func Secret(user, realm string) string {
	if user == "john" {
		// password is "hello"
		return "$1$dlPL2MqE$oQmn16q49SqdmhenQuNgs1"
	}
	return ""
}

type MainController struct {
	beego.Controller
}

func (this *MainController) Prepare() {
	a := auth.NewBasicAuthenticator("example.com", Secret)
	if username := a.CheckAuth(this.Ctx.Request); username == "" {
		a.RequireAuth(this.Ctx.ResponseWriter, this.Ctx.Request)
	}
}

func (this *MainController) Get() {
	this.Data["Username"] = "astaxie"
	this.Data["Email"] = "astaxie@gmail.com"
	this.TplNames = "index.tpl"
}

The above code takes advantage of Beego's prepare() function to perform authentication before allowing the normal flow of execution to proceed; as you can see, it's very simple to implement HTTP authentication. Digest authentication can be implemented in much the same way.

OAuth and OAuth 2 certification

OAuth and OAuth 2 is currently more popular two authentication methods, but fortunately, there is a third-party library to achieve this certification, but it is realized abroad, and did not QQ, microblogging like domestic application certified integration:

github.com/bradrydzewski/go.auth

The following code demonstrates how to put the library in order to achieve the introduction of beego OAuth authentication, an example to demonstrate GitHub here:

1. Add two routes

    beego.RegisterController("/auth/login", &controllers.GithubController{})
    beego.RegisterController("/mainpage", &controllers.PageController{})
   

2. Then we deal GithubController landing page:

    package controllers
   
    import (
    	"github.com/astaxie/beego"
    	"github.com/bradrydzewski/go.auth"
    )
   
    const (
    	githubClientKey = "a0864ea791ce7e7bd0df"
    	githubSecretKey = "a0ec09a647a688a64a28f6190b5a0d2705df56ca"
    )
   
    type GithubController struct {
    	beego.Controller
    }
   
    func (this *GithubController) Get() {
    	// set the auth parameters
    	auth.Config.CookieSecret = []byte("7H9xiimk2QdTdYI7rDddfJeV")
    	auth.Config.LoginSuccessRedirect = "/mainpage"
    	auth.Config.CookieSecure = false
   
    	githubHandler := auth.Github(githubClientKey, githubSecretKey)
   
    	githubHandler.ServeHTTP(this.Ctx.ResponseWriter, this.Ctx.Request)
    }
   

3. treatment after successful landing pages

    package controllers
   
    import (
    	"github.com/astaxie/beego"
    	"github.com/bradrydzewski/go.auth"
    	"net/http"
    	"net/url"
    )
   
    type PageController struct {
    	beego.Controller
    }
   
    func (this *PageController) Get() {
    	// set the auth parameters
    	auth.Config.CookieSecret = []byte("7H9xiimk2QdTdYI7rDddfJeV")
    	auth.Config.LoginSuccessRedirect = "/mainpage"
    	auth.Config.CookieSecure = false
   
    	user, err := auth.GetUserCookie(this.Ctx.Request)
   
    	//if no active user session then authorize user
    	if err != nil || user.Id() == "" {
    		http.Redirect(this.Ctx.ResponseWriter, this.Ctx.Request, auth.Config.LoginRedirect, http.StatusSeeOther)
    		return
    	}
   
    	//else, add the user to the URL and continue
    	this.Ctx.Request.URL.User = url.User(user.Id())
    	this.Data["pic"] = user.Picture()
    	this.Data["id"] = user.Id()
    	this.Data["name"] = user.Name()
    	this.TplNames = "home.tpl"
    }
   

The whole process is as follows, first open your browser and enter the address:

Figure 14.4 shows the home page with a log in button

Then click on the link following screen appears:

Figure 14.5 is displayed after clicking the log in button authorization GitHub page

Then click Authorize app will appear the following interface:

Figure 14.6 is displayed after log in authorization to obtain information page GitHub

Custom authentication

Custom authentication and session are generally a combination of proven, the following code from an open source based beego blog:

//Login process
func (this *LoginController) Post() {
	this.TplNames = "login.tpl"
	this.Ctx.Request.ParseForm()
	username := this.Ctx.Request.Form.Get("username")
	password := this.Ctx.Request.Form.Get("password")
	md5Password := md5.New()
	io.WriteString(md5Password, password)
	buffer := bytes.NewBuffer(nil)
	fmt.Fprintf(buffer, "%x", md5Password.Sum(nil))
	newPass := buffer.String()

	now := time.Now().Format("2006-01-02 15:04:05")

	userInfo := models.GetUserInfo(username)
	if userInfo.Password == newPass {
		var users models.User
		users.Last_logintime = now
		models.UpdateUserInfo(users)

		//Set the session successful login
		sess := globalSessions.SessionStart(this.Ctx.ResponseWriter, this.Ctx.Request)
		sess.Set("uid", userInfo.Id)
		sess.Set("uname", userInfo.Username)

		this.Ctx.Redirect(302, "/")
	}	
}

//Registration process
func (this *RegController) Post() {
	this.TplNames = "reg.tpl"
	this.Ctx.Request.ParseForm()
	username := this.Ctx.Request.Form.Get("username")
	password := this.Ctx.Request.Form.Get("password")
	usererr := checkUsername(username)
	fmt.Println(usererr)
	if usererr == false {
		this.Data["UsernameErr"] = "Username error, Please to again"
		return
	}

	passerr := checkPassword(password)
	if passerr == false {
		this.Data["PasswordErr"] = "Password error, Please to again"
		return
	}

	md5Password := md5.New()
	io.WriteString(md5Password, password)
	buffer := bytes.NewBuffer(nil)
	fmt.Fprintf(buffer, "%x", md5Password.Sum(nil))
	newPass := buffer.String()

	now := time.Now().Format("2006-01-02 15:04:05")

	userInfo := models.GetUserInfo(username)

	if userInfo.Username == "" {
		var users models.User
		users.Username = username
		users.Password = newPass
		users.Created = now
		users.Last_logintime = now
		models.AddUser(users)

		//Set the session successful login
		sess := globalSessions.SessionStart(this.Ctx.ResponseWriter, this.Ctx.Request)
		sess.Set("uid", userInfo.Id)
		sess.Set("uname", userInfo.Username)
		this.Ctx.Redirect(302, "/")
	} else {
		this.Data["UsernameErr"] = "User already exists"
	}

}

func checkPassword(password string) (b bool) {
	if ok, _ := regexp.MatchString("^[a-zA-Z0-9]{4,16}$", password); !ok {
		return false
	}
	return true
}

func checkUsername(username string) (b bool) {
	if ok, _ := regexp.MatchString("^[a-zA-Z0-9]{4,16}$", username); !ok {
		return false
	}
	return true
}

With the user log in and registration, where you can add other modules such as the judgment of whether the user log in:

func (this *AddBlogController) Prepare() {
	sess := globalSessions.SessionStart(this.Ctx.ResponseWriter, this.Ctx.Request)
	sess_uid := sess.Get("userid")
	sess_username := sess.Get("username")
	if sess_uid == nil {
		this.Ctx.Redirect(302, "/admin/login")
		return
	}
	this.Data["Username"] = sess_username
}

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