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config.go
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config.go
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package sshc
import (
"bufio"
"bytes"
"fmt"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"github.com/kevinburke/ssh_config"
"golang.org/x/crypto/ssh"
)
var (
defaultConfigPaths = []string{
filepath.Join("~", ".ssh", "config"),
filepath.Join("/", "etc", "ssh", "ssh_config"),
}
includeRelRe = regexp.MustCompile(`^(Include\s+~)(.+)$`)
includeRelRe2 = regexp.MustCompile(`^(Include\s+)([^~/].+)$`)
)
type sshConfig struct {
sc *ssh_config.Config
path string
}
// Config is the type for the SSH Client config. not ssh_config.
type Config struct {
configPaths []string
hostname string
user string
port int
identityKey []byte
passphrase []byte
useAgent bool
sshConfigs []*sshConfig
knownhosts []string
password string
auth []ssh.AuthMethod
}
// Option is the type for change Config.
type Option func(*Config) error
// NewConfig creates SSH client config.
func NewConfig(options ...Option) (*Config, error) {
var err error
c := &Config{
configPaths: defaultConfigPaths,
useAgent: true, // Default is true
}
for _, option := range options {
err = option(c)
if err != nil {
return nil, err
}
}
homeDir, err := os.UserHomeDir()
if err != nil {
return nil, err
}
for _, p := range c.configPaths {
cPath := filepath.Clean(strings.Replace(p, "~", homeDir, 1))
if _, err := os.Lstat(cPath); err != nil {
continue
}
f, err := os.Open(cPath)
if err != nil {
return nil, err
}
buf := new(bytes.Buffer)
s := bufio.NewScanner(f)
for s.Scan() {
line := s.Bytes()
// Replace include path
if includeRelRe.Match(line) {
line = includeRelRe.ReplaceAll(line, []byte(fmt.Sprintf("Include %s$2", homeDir)))
} else if includeRelRe2.Match(line) {
line = includeRelRe2.ReplaceAll(line, []byte(fmt.Sprintf("Include %s/.ssh/$2", homeDir)))
}
if _, err := buf.Write(append(line, []byte("\n")...)); err != nil {
return nil, err
}
}
cfg, err := ssh_config.Decode(buf)
if err != nil {
return nil, err
}
c.sshConfigs = append([]*sshConfig{{path: cPath, sc: cfg}}, c.sshConfigs...)
}
return c, nil
}
// Get returns Config value.
func (c *Config) Get(host, key string) string {
// Return the value overridden by option
switch key {
case "User":
return c.getUser(host)
case "Port":
p, err := c.getPort(host)
if err != nil {
return ""
}
return strconv.Itoa(p)
case "Hostname":
h, err := c.getHostname(host)
if err != nil {
return ""
}
return h
}
return c.getRaw(host, key)
}
func (c *Config) getRaw(host, key string) string {
for _, scs := range c.sshConfigs {
val, err := scs.sc.Get(host, key)
if err != nil || val != "" {
return val
}
}
return ssh_config.Default(key)
}
func (c *Config) getRawWithBase(host, key string) (string, string) {
for _, scs := range c.sshConfigs {
val, err := scs.sc.Get(host, key)
if err != nil || val != "" {
return val, filepath.Dir(scs.path)
}
}
return ssh_config.Default(key), ""
}
func (c *Config) getUser(host string) string {
if c.user != "" {
return c.user
}
return c.getRaw(host, "User")
}
func (c *Config) getPort(host string) (int, error) {
if c.port != 0 {
return c.port, nil
}
p := c.getRaw(host, "Port")
return strconv.Atoi(p)
}
func (c *Config) getHostname(host string) (string, error) {
if c.hostname != "" {
return c.hostname, nil
}
h := c.getRaw(host, "Hostname")
if h == "" {
return host, nil
}
return h, nil
}
func (c *Config) getIdentityKey(host string) ([]byte, error) {
if c.identityKey != nil {
return c.identityKey, nil
}
user := c.getUser(host)
port, err := c.getPort(host)
if err != nil {
return nil, err
}
hostname, err := c.getHostname(host)
if err != nil {
return nil, err
}
keyPath, base := c.getRawWithBase(host, "IdentityFile")
keyPath = expandVerbs(keyPath, user, port, hostname)
keyPath, err = expandPath(keyPath, base)
if err != nil {
return nil, err
}
if i, _ := expandPath("~/.ssh/identity", base); keyPath == i {
if _, err := os.Lstat(i); err != nil {
keyPath, err = expandPath("~/.ssh/id_rsa", base)
if err != nil {
return nil, err
}
}
}
return os.ReadFile(keyPath)
}
func (c *Config) getProxyCommand(host string) (string, string) {
return c.getRawWithBase(host, "ProxyCommand")
}
// User returns Option that set Config.user for override SSH client user.
func User(u string) Option {
return func(c *Config) error {
c.user = u
return nil
}
}
// Port returns Option that set Config.port for override SSH client port.
func Port(p int) Option {
return func(c *Config) error {
c.port = p
return nil
}
}
// Hostname returns Option that set Config.hostname for override SSH client port.
func Hostname(h string) Option {
return func(c *Config) error {
c.hostname = h
return nil
}
}
// IdentityFile returns Option that set Config.identityKey for override SSH client identity file.
func IdentityFile(p string) Option {
return func(c *Config) error {
key, err := os.ReadFile(filepath.Clean(p))
if err != nil {
return err
}
c.identityKey = key
return nil
}
}
// IdentityKey returns Option that set Config.identityKey for override SSH client identity file.
func IdentityKey(b []byte) Option {
return func(c *Config) error {
c.identityKey = b
return nil
}
}
// Passphrase returns Option that set Config.passphrase for set SSH key passphrase.
func Passphrase(p []byte) Option {
return func(c *Config) error {
c.passphrase = p
return nil
}
}
// ConfigPath is alias of UnshiftConfigPath.
func ConfigPath(p string) Option {
return UnshiftConfigPath(p)
}
// UnshiftConfigPath returns Option that unshift ssh_config path to Config.configpaths.
func UnshiftConfigPath(p string) Option {
return func(c *Config) error {
c.configPaths = unique(append([]string{p}, c.configPaths...))
return nil
}
}
// AppendConfigPath returns Option that append ssh_config path to Config.configpaths.
func AppendConfigPath(p string) Option {
return func(c *Config) error {
c.configPaths = unique(append(c.configPaths, p))
return nil
}
}
// ClearConfigPath returns Option thet clear Config.configpaths,
func ClearConfigPath() Option {
return func(c *Config) error {
c.configPaths = []string{}
return nil
}
}
// UseAgent returns Option that override Config.useAgent.
func UseAgent(u bool) Option {
return func(c *Config) error {
c.useAgent = u
return nil
}
}
// Knownhosts returns Option that override Config.knownhosts.
func Knownhosts(files ...string) Option {
return func(c *Config) error {
c.knownhosts = files
return nil
}
}
// Password returns Option that override Config.password
func Password(pass string) Option {
return func(c *Config) error {
c.password = pass
return nil
}
}
// AuthMethod returns Option that append ssh.AuthMethod to Config.auth
func AuthMethod(m ssh.AuthMethod) Option {
return func(c *Config) error {
c.auth = append(c.auth, m)
return nil
}
}
func unique(s []string) []string {
keys := make(map[string]bool)
l := []string{}
for _, e := range s {
if _, v := keys[e]; !v {
keys[e] = true
l = append(l, e)
}
}
return l
}
func expandPath(path, base string) (string, error) {
switch {
case strings.HasPrefix(path, "/"):
return path, nil
case strings.HasPrefix(path, "~"):
homeDir, err := os.UserHomeDir()
if err != nil {
return "", err
}
return filepath.Clean(strings.Replace(path, "~", homeDir, 1)), nil
default:
return filepath.Clean(filepath.Join(base, path)), nil
}
}