How to log in golang

How to log in to Golang

Golang is an open source programming language that was launched by Google in 2009. Golang is widely used in back-end development, cloud computing and other fields because of its advantages such as efficiency, reliability, and easy maintenance. In Golang development, due to the need to implement user login and other functions, how to implement user login in Golang has become an important issue. This article will introduce how to implement user login in Golang.

1. The principle of user login in Golang

To implement the user login function, user information, such as user name, password, etc., needs to be saved on the server side. When the user enters the user name and password, the server needs to verify the user's input. If the match is successful, the server will return authentication success information to the user and save the user's login status on the server side. The login status can be saved in the form of cookies or sessions, so that the server can identify the user the next time he visits and return the corresponding data.

2. Steps to implement user login in Golang

To implement user login in Golang, you need to complete the following steps:

1. Create a database table

Create a user table in the database to save the user's user name, password and other information, as shown below:

CREATE TABLE users (
ID int NOT NULL AUTO_INCREMENT,
Name varchar( 20) NOT NULL,
Password varchar(50) NOT NULL,
PRIMARY KEY (ID)
);

2. Write login page

In the front-end page, input boxes for username and password need to be provided. After the user enters his account and password, click the login button, and a request will be sent to the server. The request needs to include the account and password information entered by the user.

3. Writing Golang interface

After receiving the request from the front-end page, the server needs to write the corresponding interface to receive and process the request. The processing steps are as follows:

(1) Obtain the user name and password information carried in the request.

(2) Connect to the database and verify the user name and password entered by the user. If the username and password match successfully, successful authentication information is returned and the found user information is saved on the server.

(3) Return login status information to the front end.

4. Save login status

In Golang, user login status can be saved through the session or cookie mechanism. The session is some information saved on the server side, and the cookie is some information saved on the client side. After the user successfully logs in, the server can save the user information in the session and save the session identification information in the cookie so that the server can identify the user the next time he visits.

5. Security issues of user information

During the user login process, the security of user information needs to be ensured. The user's password needs to be encrypted. In Golang, the bcrypt algorithm can be used to encrypt passwords. The bcrypt encryption algorithm is a secure hashing algorithm that repeatedly hashes passwords in multiple rounds, thereby enhancing password security.

3. Example of implementing user login in Golang

The following is a simple example that demonstrates how to implement user login in Golang.

1. Create user table

Execute the following SQL statement in MySQL:

CREATE TABLE users (
ID int NOT NULL AUTO_INCREMENT,
Name varchar(20) NOT NULL,
Password varchar(100) NOT NULL,
PRIMARY KEY (ID)
);

2. Write login page

In the HTML file, you can write the following code:

<meta charset="UTF-8" />
<title>Login Page</title>

<h1>Login Page</h1>
<form action="/login" method="POST">
  <label for="username">Username:</label>
  <input type="text" id="username" name="username" /><br />
  <label for="password">Password:</label>
  <input type="password" id="password" name="password" /><br />
  <input type="submit" name="submit" value="Login" />
</form>

3. Writing Golang code

The Golang code is as follows:

package main

import (

"crypto/rand"
"database/sql"
"fmt"
"html/template"
"log"
"net/http"
"strings"
"time"

"golang.org/x/crypto/bcrypt"

_ "github.com/go-sql-driver/mysql"

)

type User struct {

ID       int    `json:"id"`
Name     string `json:"name"`
Password string `json:"password"`

}

var db *sql.DB

func dbSetup() {

var err error
db, err = sql.Open("mysql",
    "username:password@tcp(localhost:3306)/dbname")
if err != nil {
    log.Fatal(err)
}

}

func dbClose() {

db.Close()

}

func UserExists(username string) bool {

var count int
stmt := "SELECT COUNT(*) FROM users WHERE Name = ?"
row := db.QueryRow(stmt, username)
err := row.Scan(&count)
if err != nil {
    log.Fatal(err)
}
return count > 0

}

func AddUser(user User) {

stmt := "INSERT INTO users(Name, Password) VALUES(?, ?)"
_, err := db.Exec(stmt, user.Name, user.Password)
if err != nil {
    log.Fatal(err)
}

}

func GetUserByUsername( username string) (User, error) {

var user User
stmt := "SELECT ID, Name, Password FROM users WHERE Name = ?"
row := db.QueryRow(stmt, username)
err := row.Scan(&user.ID, &user.Name, &user.Password)
switch {
case err == sql.ErrNoRows:
    return User{}, fmt.Errorf("No user with username %s", username)
case err != nil:
    return User{}, err
}
return user, nil

}

func HashPassword(password string) (string, error) {

bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
return string(bytes), err

}

func CheckPasswordHash(password, hash string) bool {

err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
return err == nil

}

func LoginHandler(w http.ResponseWriter, r *http.Request) {

if r.Method == "GET" {
    t, _ := template.ParseFiles("login.html")
    t.Execute(w, nil)
} else {
    r.ParseForm()
    username := strings.TrimSpace(r.Form.Get("username"))
    password := strings.TrimSpace(r.Form.Get("password"))

    if !UserExists(username) {
        http.Error(w, "User not found.", http.StatusUnauthorized)
        return
    }

    user, err := GetUserByUsername(username)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    if !CheckPasswordHash(password, user.Password) {
        http.Error(w, "Invalid credentials.", http.StatusUnauthorized)
        return
    }

    sessionID := createSession()
    cookie := &http.Cookie{
        Name:     "sessionid",
        Value:    sessionID,
        Path:     "/",
        Expires:  time.Now().Add(time.Hour * 24 * 7),
        HttpOnly: true,
    }
    http.SetCookie(w, cookie)

    fmt.Fprintf(w, "Welcome, %s!", user.Name)
}

}

func createSession() string {

b := make([]byte, 16)
_, err := rand.Read(b)
if err != nil {
    log.Fatal(err)
}
return fmt.Sprintf("%x", b)

}

func main() {

dbSetup()
defer dbClose()

http.HandleFunc("/login", LoginHandler)

log.Fatal(http.ListenAndServe(":8080", nil))

}

The above code implements the user login function. Its logic mainly includes steps such as determining whether the user exists, verifying the password, generating session ID, and creating cookies. For specific implementation, please refer to the comments in the code.

4. Summary

To implement the user login function in Golang, the main steps that need to be completed include creating a user table, writing a login page, writing a Golang interface, saving login status, and ensuring the security of user information. question. During the implementation process, attention needs to be paid to the security of user information. This article uses a simple example to introduce how to implement the user login function in Golang. On this basis, readers can expand to implement more complex functions.

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