235 lines
7.3 KiB
Go
235 lines
7.3 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of go-ethereum.
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//
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// go-ethereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// go-ethereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
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package main
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"io/ioutil"
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"net"
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"os"
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"os/user"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/ethereum/go-ethereum/log"
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"golang.org/x/crypto/ssh"
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"golang.org/x/crypto/ssh/terminal"
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)
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// sshClient is a small wrapper around Go's SSH client with a few utility methods
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// implemented on top.
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type sshClient struct {
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server string // Server name or IP without port number
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address string // IP address of the remote server
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pubkey []byte // RSA public key to authenticate the server
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client *ssh.Client
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logger log.Logger
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}
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// dial establishes an SSH connection to a remote node using the current user and
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// the user's configured private RSA key. If that fails, password authentication
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// is fallen back to. The caller may override the login user via user@server:port.
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func dial(server string, pubkey []byte) (*sshClient, error) {
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// Figure out a label for the server and a logger
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label := server
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if strings.Contains(label, ":") {
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label = label[:strings.Index(label, ":")]
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}
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login := ""
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if strings.Contains(server, "@") {
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login = label[:strings.Index(label, "@")]
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label = label[strings.Index(label, "@")+1:]
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server = server[strings.Index(server, "@")+1:]
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}
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logger := log.New("server", label)
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logger.Debug("Attempting to establish SSH connection")
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user, err := user.Current()
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if err != nil {
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return nil, err
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}
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if login == "" {
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login = user.Username
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}
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// Configure the supported authentication methods (private key and password)
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var auths []ssh.AuthMethod
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path := filepath.Join(user.HomeDir, ".ssh", "id_rsa")
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if buf, err := ioutil.ReadFile(path); err != nil {
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log.Warn("No SSH key, falling back to passwords", "path", path, "err", err)
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} else {
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key, err := ssh.ParsePrivateKey(buf)
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if err != nil {
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log.Warn("Bad SSH key, falling back to passwords", "path", path, "err", err)
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} else {
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auths = append(auths, ssh.PublicKeys(key))
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}
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}
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auths = append(auths, ssh.PasswordCallback(func() (string, error) {
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fmt.Printf("What's the login password for %s at %s? (won't be echoed)\n> ", login, server)
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blob, err := terminal.ReadPassword(int(syscall.Stdin))
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fmt.Println()
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return string(blob), err
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}))
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// Resolve the IP address of the remote server
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addr, err := net.LookupHost(label)
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if err != nil {
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return nil, err
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}
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if len(addr) == 0 {
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return nil, errors.New("no IPs associated with domain")
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}
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// Try to dial in to the remote server
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logger.Trace("Dialing remote SSH server", "user", login)
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if !strings.Contains(server, ":") {
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server += ":22"
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}
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keycheck := func(hostname string, remote net.Addr, key ssh.PublicKey) error {
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// If no public key is known for SSH, ask the user to confirm
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if pubkey == nil {
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fmt.Printf("The authenticity of host '%s (%s)' can't be established.\n", hostname, remote)
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fmt.Printf("SSH key fingerprint is %s [MD5]\n", ssh.FingerprintLegacyMD5(key))
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fmt.Printf("Are you sure you want to continue connecting (yes/no)? ")
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text, err := bufio.NewReader(os.Stdin).ReadString('\n')
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switch {
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case err != nil:
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return err
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case strings.TrimSpace(text) == "yes":
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pubkey = key.Marshal()
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return nil
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default:
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return fmt.Errorf("unknown auth choice: %v", text)
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}
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}
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// If a public key exists for this SSH server, check that it matches
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if bytes.Equal(pubkey, key.Marshal()) {
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return nil
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}
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// We have a mismatch, forbid connecting
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return errors.New("ssh key mismatch, readd the machine to update")
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}
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client, err := ssh.Dial("tcp", server, &ssh.ClientConfig{User: login, Auth: auths, HostKeyCallback: keycheck})
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if err != nil {
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return nil, err
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}
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// Connection established, return our utility wrapper
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c := &sshClient{
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server: label,
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address: addr[0],
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pubkey: pubkey,
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client: client,
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logger: logger,
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}
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if err := c.init(); err != nil {
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client.Close()
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return nil, err
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}
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return c, nil
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}
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// init runs some initialization commands on the remote server to ensure it's
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// capable of acting as puppeth target.
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func (client *sshClient) init() error {
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client.logger.Debug("Verifying if docker is available")
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if out, err := client.Run("docker version"); err != nil {
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if len(out) == 0 {
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return err
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}
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return fmt.Errorf("docker configured incorrectly: %s", out)
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}
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client.logger.Debug("Verifying if docker-compose is available")
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if out, err := client.Run("docker-compose version"); err != nil {
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if len(out) == 0 {
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return err
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}
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return fmt.Errorf("docker-compose configured incorrectly: %s", out)
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}
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return nil
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}
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// Close terminates the connection to an SSH server.
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func (client *sshClient) Close() error {
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return client.client.Close()
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}
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// Run executes a command on the remote server and returns the combined output
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// along with any error status.
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func (client *sshClient) Run(cmd string) ([]byte, error) {
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// Establish a single command session
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session, err := client.client.NewSession()
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if err != nil {
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return nil, err
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}
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defer session.Close()
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// Execute the command and return any output
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client.logger.Trace("Running command on remote server", "cmd", cmd)
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return session.CombinedOutput(cmd)
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}
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// Stream executes a command on the remote server and streams all outputs into
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// the local stdout and stderr streams.
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func (client *sshClient) Stream(cmd string) error {
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// Establish a single command session
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session, err := client.client.NewSession()
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if err != nil {
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return err
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}
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defer session.Close()
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session.Stdout = os.Stdout
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session.Stderr = os.Stderr
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// Execute the command and return any output
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client.logger.Trace("Streaming command on remote server", "cmd", cmd)
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return session.Run(cmd)
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}
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// Upload copied the set of files to a remote server via SCP, creating any non-
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// existing folder in te mean time.
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func (client *sshClient) Upload(files map[string][]byte) ([]byte, error) {
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// Establish a single command session
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session, err := client.client.NewSession()
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if err != nil {
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return nil, err
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}
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defer session.Close()
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// Create a goroutine that streams the SCP content
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go func() {
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out, _ := session.StdinPipe()
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defer out.Close()
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for file, content := range files {
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client.logger.Trace("Uploading file to server", "file", file, "bytes", len(content))
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fmt.Fprintln(out, "D0755", 0, filepath.Dir(file)) // Ensure the folder exists
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fmt.Fprintln(out, "C0644", len(content), filepath.Base(file)) // Create the actual file
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out.Write(content) // Stream the data content
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fmt.Fprint(out, "\x00") // Transfer end with \x00
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fmt.Fprintln(out, "E") // Leave directory (simpler)
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}
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}()
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return session.CombinedOutput("/usr/bin/scp -v -tr ./")
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}
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