getSSHClient.go

/*
Copyright © 2023 Miha miha.kralj@outlook.com

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package internal

import (
	"fmt"
	"net"
	"strings"
	"syscall"

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

type SSHClient struct {
	Session *ssh.Session
	Client  *ssh.Client
}

var (
	SshClient *SSHClient
	SSHTarget string
	config    *ssh.ClientConfig
)

func getSSHClient(target string) (*SSHClient, error) {
	var user, host, port string

	userhost, port, err := net.SplitHostPort(target)
	if err != nil {
		userhost = target
	}
	if port == "" {
		port = "22"
	}
	split := strings.SplitN(userhost, "@", 2)
	if len(split) == 2 {
		user = split[0]
		host = split[1]
	} else {
		user = "admin"
		host = userhost
	}

	var connection *ssh.Client

	if config == nil {
		config = &ssh.ClientConfig{
			User:            user,
			Auth:            []ssh.AuthMethod{},
			HostKeyCallback: ssh.InsecureIgnoreHostKey(),
		}

		//try to get sshAgent
		sshAgent, err := GetSSHAgent()
		if err == nil {
			config.Auth = append(config.Auth, sshAgent)
			if len(config.Auth) > 0 {
				connection, err = ssh.Dial("tcp", host+":"+port, config)
				if err == nil {
					return &SSHClient{Client: connection}, nil
				}
			}
		}
		fmt.Println("No authorized SSH keys found in local ssh agent, reverting to password-based access.\nTo enable seamless access, use the 'ssh-add' to add the authorized key for user", user)
		fmt.Printf("Enter password for %s@%s: ", user, host)
		bytePassword, err := term.ReadPassword(int(syscall.Stdin))
		if err != nil {
			Log(5, "failed to read password: %v", err)
		}
		password := string(bytePassword)
		config.Auth = []ssh.AuthMethod{ssh.Password(password)}
		connection, err = ssh.Dial("tcp", host+":"+port, config)
		if err != nil {
			fmt.Println()
			Log(1, "%v", err)
		} else {
			fmt.Println()
			return &SSHClient{Client: connection}, nil
		}
	}
	connection, err = ssh.Dial("tcp", host+":"+port, config)
	if err != nil {
		Log(1, "%v", err)
	}
	SshClient = &SSHClient{Client: connection}

	return SshClient, nil
}