How to use network programming functions in Go language to upload files to FTP server?

How to use network programming functions in Go language to upload files to FTP server?

Introduction:
FTP (File Transfer Protocol) is a commonly used file transfer protocol on the Internet. It implements file upload, download, and deletion operations by establishing a data connection between the client and the server. This article will introduce how to use network programming functions in the Go language to implement a simple FTP server, and demonstrate how to use the server to upload files.

Implementing the FTP server:
First, we need to import the "net" package and "log" package of the Go language in order to use network programming functions and output logs.

package main

import (
    "log"
    "net"
)

func main() {
    // 监听服务器的地址和端口
    listen, err := net.Listen("tcp", "localhost:2121")
    if err != nil {
        log.Fatal(err)
    }

    defer listen.Close()

    log.Printf("服务器已启动，等待客户端连接...")
    for {
        // 等待客户端连接
        conn, err := listen.Accept()
        if err != nil {
            log.Fatal(err)
        }

        go handleConn(conn)
    }
}

func handleConn(conn net.Conn) {
    defer conn.Close()

    // 读取客户端发送的命令
    buf := make([]byte, 1024)
    _, err := conn.Read(buf)
    if err != nil {
        log.Println(err)
        return
    }

    // 处理客户端上传的文件
    // 你可以在这里编写具体的代码逻辑，实现文件的接收和存储

}

The above is the implementation of a simple FTP server, which listens to port 2121 of the local host and waits for client connections. When a client connects, the server will start a new goroutine to handle the connection.

In the client connection processing function handleConn, we use the conn.Read() function to read the command sent by the client. For the FTP protocol, the client usually sends a STOR command when uploading files. You can parse and process commands according to specific needs.

File upload:
In the handleConn function, we can use conn.Read()or other related functions to receive and store files uploaded by the client. The following is a simple sample code that demonstrates how to save files uploaded by the client to the local computer.

func handleConn(conn net.Conn) {
    defer conn.Close()

    // 读取客户端发送的命令
    buf := make([]byte, 1024)
    n, err := conn.Read(buf)
    if err != nil {
        log.Println(err)
        return
    }

    // 解析命令
    cmd := string(buf[:n])
    if cmd[:4] != "STOR" {
        log.Println("未知命令：", cmd)
        return
    }

    // 从命令中获取文件名
    fileName := cmd[5:]

    // 创建本地文件
    file, err := os.Create(fileName)
    if err != nil {
        log.Println(err)
        return
    }
    defer file.Close()

    // 读取客户端上传的文件数据，并保存至本地文件
    for {
        n, err := conn.Read(buf)
        if err != nil {
            if err != io.EOF {
                log.Println(err)
            }
            break
        }

        _, err = file.Write(buf[:n])
        if err != nil {
            log.Println(err)
            break
        }
    }

    log.Println("文件上传成功：", fileName)
}

In the above code, we use the os.Create() function to create a local file, and then use the conn.Read() function to read the file uploaded by the client data and writes the data to a local file.

Note:

• The above code only implements a simple FTP server function to upload files. For more complex functions, such as user identity authentication, security, etc., you need Expand based on specific needs.
• When processing file uploads, attention should be paid to validation and handling errors to ensure that uploaded files are saved correctly.
• In order to make the code more robust and reliable, you may need to add more error handling and log output in actual use.

Summary:
This article demonstrates how to use network programming functions in the Go language to implement a simple FTP server, and how to use the server to upload files. By learning and understanding these implementation methods, you can further expand the functionality and implement a more powerful FTP server. At the same time, I also hope that this article can provide you with some help in network programming and Go language learning.

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