Remote file transfer using Go language

preface

The previous article described how to use Go to execute remote commands via the SSH protocol: How to use Go to execute remote commands similarly, Go can be used to transfer files remotely via the SSH protocol.

In addition to the SSH library, you need to transfer files github.com/pkg/sftp This library.

implementation

Without further ado, just look at the code. Since it is a remote file transfer based on the SSH protocol, the SSH connection is created first, and then the sftp client for the transfer file is created.

func connect(user, password, host string, port int) (*sftp.Client, error) { 
 var (
 auth   []ssh.AuthMethod
 addr   string
 clientConfig *ssh.ClientConfig
 sshClient *ssh.Client
 sftpClient *sftp.Client
 err   error
 )
 // get auth method
 auth = make([]ssh.AuthMethod, 0)
 auth = append(auth, ssh.Password(password))

 clientConfig = &ssh.ClientConfig{
 User: user,
 Auth: auth,
 Timeout: 30 * time.Second,
 }

 // connet to ssh
 addr = fmt.Sprintf("%s:%d", host, port)

 if sshClient, err = ssh.Dial("tcp", addr, clientConfig); err != nil {
 return nil, err
 }

 // create sftp client
 if sftpClient, err = sftp.NewClient(sshClient); err != nil {
 return nil, err
 }

 return sftpClient, nil
}

Send a file

After creating sftpClient using the connect method above, sending the file is simple.

package main

import ( 
 "fmt"
 "log"
 "os"
 "path"
 "time"

 "github.com/pkg/sftp"

 "golang.org/x/crypto/ssh"
)

func main() { 
 var (
 err  error
 sftpClient *sftp.Client
 )

 //  Let me put it in real terms  SSH  Of the connection   User name, password, host name or IP . SSH port 
 sftpClient, err = connect("root", "rootpass", "127.0.0.1", 22)
 if err != nil {
 log.Fatal(err)
 }
 defer sftpClient.Close()

 //  The local file path used to test   and   Folders on remote machines 
 var localFilePath = "/path/to/local/file/test.txt"
 var remoteDir = "/remote/dir/"
 srcFile, err := os.Open(localFilePath)
 if err != nil {
 log.Fatal(err)
 }
 defer srcFile.Close()

 var remoteFileName = path.Base(localFilePath)
 dstFile, err := sftpClient.Create(path.Join(remoteDir, remoteFileName))
 if err != nil {
 log.Fatal(err)
 }
 defer dstFile.Close()

 buf := make([]byte, 1024)
 for {
 n, _ := srcFile.Read(buf)
 if n == 0 {
  break
 }
 dstFile.Write(buf)
 }

 fmt.Println("copy file to remote server finished!")
}

Access to the file

Getting files from a remote machine is slightly different, but also simple.

package main

import ( 
 "fmt"
 "log"
 "os"
 "path"
 "time"

 "github.com/pkg/sftp"

 "golang.org/x/crypto/ssh"
)

func main() {

 var (
 err  error
 sftpClient *sftp.Client
 )

 //  Let me put it in real terms  SSH  Of the connection   User name, password, host name or IP . SSH port 
 sftpClient, err = connect("root", "rootpass", "127.0.0.1", 22)
 if err != nil {
 log.Fatal(err)
 }
 defer sftpClient.Close()

 //  The remote file path used to test   and   Local folder 
 var remoteFilePath = "/path/to/remote/path/test.txt"
 var localDir = "/local/dir"

 srcFile, err := sftpClient.Open(remoteFilePath)
 if err != nil {
 log.Fatal(err)
 }
 defer srcFile.Close()

 var localFileName = path.Base(remoteFilePath)
 dstFile, err := os.Create(path.Join(localDir, localFileName))
 if err != nil {
 log.Fatal(err)
 }
 defer dstFile.Close()

 if _, err = srcFile.WriteTo(dstFile); err != nil {
 log.Fatal(err)
 }

 fmt.Println("copy file from remote server finished!")
}

conclusion

The above example only demonstrates the file transfer, the transfer folder is also very simple, but more steps to traverse the folder and create the folder, the specific function can see doc in the sftp library. That's all for remote file transfer in Go language. I hope this article is helpful for you to learn Go language.