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