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config.go
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config.go
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package config
import (
"bufio"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"os"
"path"
"path/filepath"
"sort"
"strings"
"time"
"github.com/moul/flexyaml"
"github.com/moul/advanced-ssh-config/pkg/logger"
"github.com/moul/advanced-ssh-config/pkg/utils"
"github.com/moul/advanced-ssh-config/pkg/version"
)
var asshBinaryPath = "assh"
const defaultSSHConfigPath = "~/.ssh/config"
// Config contains a list of Hosts sections and a Defaults section representing a configuration file
type Config struct {
Hosts HostsMap `yaml:"hosts,omitempty,flow" json:"hosts"`
Templates HostsMap `yaml:"templates,omitempty,flow" json:"templates"`
Defaults Host `yaml:"defaults,omitempty,flow" json:"defaults,omitempty"`
Includes []string `yaml:"includes,omitempty,flow" json:"includes,omitempty"`
ASSHKnownHostFile string `yaml:"asshknownhostfile,omitempty,flow" json:"asshknownhostfile,omitempty"`
ASSHBinaryPath string `yaml:"asshbinarypath,omitempty,flow" json:"asshbinarypath,omitempty"`
includedFiles map[string]bool
sshConfigPath string
}
// DisableAutomaticRewrite will configure the ~/.ssh/config file to not automatically rewrite the configuration file
func (c *Config) DisableAutomaticRewrite() {
c.Defaults.noAutomaticRewrite = true
}
// SetASSHBinaryPath sets the default assh binary path
// this value may be overwritten in the assh.yml file using the asshbinarypath variable
func SetASSHBinaryPath(path string) {
asshBinaryPath = path
}
// String returns the JSON output
func (c *Config) String() string {
s, _ := json.Marshal(c)
return string(s)
}
// SaveNewKnownHost registers the target as a new known host and save the full known hosts list on disk
func (c *Config) SaveNewKnownHost(target string) {
c.addKnownHost(target)
path, err := utils.ExpandUser(c.ASSHKnownHostFile)
if err != nil {
logger.Logger.Errorf("Cannot append host %q, unknown ASSH known_hosts file: %v", target, err)
}
file, err := os.OpenFile(path, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0600)
if err != nil {
logger.Logger.Errorf("Cannot append host %q to %q (performance degradation): %v", target, c.ASSHKnownHostFile, err)
return
}
defer func() {
if err := file.Close(); err != nil {
panic(err)
}
}()
fmt.Fprintln(file, target)
}
func (c *Config) addKnownHost(target string) {
host := c.GetHostSafe(target)
if inst, ok := c.Hosts[host.pattern]; ok {
inst.AddKnownHost(target)
}
}
// KnownHostsFileExists returns nil if it the file exists and an error if it doesn't
func (c *Config) KnownHostsFileExists() error {
path, err := utils.ExpandUser(c.ASSHKnownHostFile)
if err != nil {
return err
}
if _, err := os.Stat(path); os.IsNotExist(err) {
return err
}
return nil
}
// LoadKnownHosts loads known hosts list from disk
func (c *Config) LoadKnownHosts() error {
path, err := utils.ExpandUser(c.ASSHKnownHostFile)
if err != nil {
return err
}
file, err := os.Open(path)
if err != nil {
return err
}
defer func() {
if err := file.Close(); err != nil {
panic(err)
}
}()
scanner := bufio.NewScanner(file)
for scanner.Scan() {
c.addKnownHost(scanner.Text())
}
return scanner.Err()
}
// IncludedFiles returns the list of the included files
func (c *Config) IncludedFiles() []string {
includedFiles := []string{}
for file := range c.includedFiles {
includedFiles = append(includedFiles, file)
}
return includedFiles
}
// JSONString returns a string representing the JSON of a Config object
func (c *Config) JSONString() ([]byte, error) {
return json.MarshalIndent(c, "", " ")
}
// computeHost returns a copy of the host with applied defaults, resolved inheritances and configured internal fields
func computeHost(host *Host, config *Config, name string, fullCompute bool) (*Host, error) {
computedHost := NewHost(name)
computedHost.pattern = name
if host != nil {
*computedHost = *host
}
// name internal field
computedHost.name = name
computedHost.inherited = make(map[string]bool)
// self is already inherited
computedHost.inherited[name] = true
// Inheritance
// FIXME: allow deeper inheritance:
// currently not resolving inherited hosts
// we should resolve all inherited hosts and pass the
// currently resolved hosts to avoid computing an host twice
for _, name := range host.Inherits {
_, found := computedHost.inherited[name]
if found {
logger.Logger.Debugf("Detected circular loop inheritance, skiping...")
continue
}
computedHost.inherited[name] = true
target, err := config.getHostByPath(name, false, false, true)
if err != nil {
logger.Logger.Warnf("Cannot inherits from %q: %v", name, err)
continue
}
computedHost.ApplyDefaults(target)
}
// fullCompute applies config.Defaults
// config.Defaults should be applied when proxying
// but should not when exporting .ssh/config file
if fullCompute {
// apply defaults based on "Host *"
computedHost.ApplyDefaults(&config.Defaults)
if computedHost.HostName == "" {
computedHost.HostName = name
}
// expands variables in host
// i.e: %h.some.zone -> {name}.some.zone
hostname := strings.Replace(computedHost.HostName, "%h", "%n", -1)
// ssh resolve '%h' in hostnames
// -> we bypass the string expansion if the input matches
// an already resolved hostname
// See https://github.com/moul/advanced-ssh-config/issues/103
pattern := strings.Replace(hostname, "%n", "*", -1)
if match, _ := path.Match(pattern, computedHost.inputName); match {
computedHost.HostName = computedHost.inputName
} else {
computedHost.HostName = computedHost.ExpandString(hostname, "")
}
}
return computedHost, nil
}
func (c *Config) getHostByName(name string, safe bool, compute bool, allowTemplate bool) (*Host, error) {
if host, ok := c.Hosts[name]; ok {
logger.Logger.Debugf("getHostByName direct matching: %q", name)
return computeHost(host, c, name, compute)
}
for origPattern, host := range c.Hosts {
patterns := append([]string{origPattern}, host.Aliases...)
for _, pattern := range patterns {
matched, err := path.Match(pattern, name)
if err != nil {
return nil, err
}
if matched {
logger.Logger.Debugf("getHostByName pattern matching: %q => %q", pattern, name)
return computeHost(host, c, name, compute)
}
}
}
if allowTemplate {
for pattern, template := range c.Templates {
matched, err := path.Match(pattern, name)
if err != nil {
return nil, err
}
if matched {
return computeHost(template, c, name, compute)
}
}
}
if safe {
host := NewHost(name)
host.HostName = name
return computeHost(host, c, name, compute)
}
return nil, fmt.Errorf("no such host: %s", name)
}
func (c *Config) getHostByPath(path string, safe bool, compute bool, allowTemplate bool) (*Host, error) {
parts := strings.SplitN(path, "/", 2)
host, err := c.getHostByName(parts[0], safe, compute, allowTemplate)
if err != nil {
return nil, err
}
if len(parts) > 1 {
host.Gateways = []string{parts[1]}
}
return host, nil
}
// GetGatewaySafe returns gateway Host configuration, a gateway is like a Host, except, the host path is not resolved
func (c *Config) GetGatewaySafe(name string) *Host {
host, err := c.getHostByName(name, true, true, false) // FIXME: fullCompute for gateway ?
if err != nil {
panic(err)
}
return host
}
// GetHost returns a matching host form Config hosts list
func (c *Config) GetHost(name string) (*Host, error) {
return c.getHostByPath(name, false, true, false)
}
// GetHostSafe won't fail, in case the host is not found, it will returns a virtual host matching the pattern
func (c *Config) GetHostSafe(name string) *Host {
host, err := c.getHostByPath(name, true, true, false)
if err != nil {
panic(err)
}
return host
}
// isSSHConfigOutdated returns true if assh.yml or an included file has a
// modification date more recent than .ssh/config
func (c *Config) isSSHConfigOutdated() (bool, error) {
filepath, err := utils.ExpandUser(c.sshConfigPath)
if err != nil {
return false, err
}
sshConfigStat, err := os.Stat(filepath)
if err != nil {
return false, err
}
sshConfigModTime := sshConfigStat.ModTime()
for filepath := range c.includedFiles {
asshConfigStat, err := os.Stat(filepath)
if err != nil {
return false, err
}
if asshConfigStat.ModTime().After(sshConfigModTime) {
return true, nil
}
}
return false, nil
}
// IsConfigOutdated returns true if .ssh/config needs to be rebuild.
// The reason may be:
// - assh.yml (or an included file) was updated recently
// - <target> matches a regex and was never seen before (not present in known-hosts file)
func (c *Config) IsConfigOutdated(target string) (bool, error) {
// check if the target is a regex and if the pattern
// was never matched before (not in known hosts)
if c.needsARebuildForTarget(target) {
c.SaveNewKnownHost(target)
return true, nil
}
// check if the ~/.ssh/config file is older than assh.yml or any included file
return c.isSSHConfigOutdated()
}
// needsARebuildForTarget returns true if the .ssh/config file needs to be rebuild for a specific target
func (c *Config) needsARebuildForTarget(target string) bool {
parts := strings.Split(target, "/")
// compute lists
aliases := map[string]bool{}
for _, host := range c.Hosts {
for _, alias := range host.Aliases {
aliases[alias] = true
}
for _, knownHost := range host.knownHosts {
aliases[knownHost] = true
}
}
patterns := []string{}
for origPattern, host := range c.Hosts {
patterns = append(patterns, origPattern)
patterns = append(patterns, host.Aliases...)
}
for _, part := range parts {
// check for direct hostname matching
if _, ok := c.Hosts[part]; ok {
continue
}
// check for direct alias matching
if _, ok := aliases[part]; ok {
continue
}
// check for pattern matching
for _, pattern := range patterns {
matched, err := path.Match(pattern, part)
if err != nil {
continue
}
if matched {
return true
}
}
}
return false
}
// LoadConfig loads the content of an io.Reader source
func (c *Config) LoadConfig(source io.Reader) error {
buf, err := ioutil.ReadAll(source)
if err != nil {
return err
}
err = flexyaml.Unmarshal(buf, &c)
if err != nil {
return err
}
c.applyMissingNames()
return nil
}
func (c *Config) applyMissingNames() {
for key, host := range c.Hosts {
if host == nil {
c.Hosts[key] = &Host{}
host = c.Hosts[key]
}
host.pattern = key
host.name = key // should be removed
host.prepare()
}
for key, template := range c.Templates {
if template == nil {
c.Templates[key] = &Host{}
template = c.Templates[key]
}
template.pattern = key
template.name = key // should be removed
template.isTemplate = true
template.prepare()
}
c.Defaults.isDefault = true
if c.Defaults.Hooks == nil {
c.Defaults.Hooks = &HostHooks{}
}
}
// SaveSSHConfig saves the configuration to ~/.ssh/config
func (c *Config) SaveSSHConfig() error {
if c.sshConfigPath == "" {
return fmt.Errorf("no Config.sshConfigPath configured")
}
configPath, err := utils.ExpandUser(c.sshConfigPath)
if err != nil {
return err
}
// validate hosts
if err = c.ValidateSummary(); err != nil {
return err
}
logger.Logger.Debugf("Writing SSH config file to %q", configPath)
tmpDir := filepath.Dir(configPath)
tmpFile, err := ioutil.TempFile(tmpDir, "config")
if err != nil {
return err
}
defer func() {
if err := os.Remove(tmpFile.Name()); err != nil {
logger.Logger.Warnf("Unable to remove tempfile: %s", tmpFile.Name())
// panic(err)
}
}()
if err := c.WriteSSHConfigTo(tmpFile); err != nil {
return err
}
if err := tmpFile.Close(); err != nil {
return err
}
return os.Rename(tmpFile.Name(), configPath)
}
// LoadFile loads the content of a configuration file in the Config object
func (c *Config) LoadFile(filename string) error {
beforeHostsCount := len(c.Hosts)
// Resolve '~' and '$HOME'
filepath, err := utils.ExpandUser(filename)
if err != nil {
return err
}
// Anti-loop protection
if _, ok := c.includedFiles[filepath]; ok {
return nil
}
c.includedFiles[filepath] = false
logger.Logger.Debugf("Loading config file '%s'", filepath)
// Read file
source, err := os.Open(filepath)
if err != nil {
return err
}
// Load config stream
err = c.LoadConfig(source)
if err != nil {
return err
}
// Successful loading
c.includedFiles[filepath] = true
afterHostsCount := len(c.Hosts)
diffHostsCount := afterHostsCount - beforeHostsCount
logger.Logger.Debugf("Loaded config file '%s' (%d + %d => %d hosts)", filepath, beforeHostsCount, afterHostsCount, diffHostsCount)
// Handling includes
for _, include := range c.Includes {
if err = c.LoadFiles(include); err != nil {
return err
}
}
return nil
}
// LoadFiles will try to glob the pattern and load each matching entries
func (c *Config) LoadFiles(pattern string) error {
// Resolve '~' and '$HOME'
expandedPattern, err := utils.ExpandUser(pattern)
if err != nil {
return err
}
// Globbing
filepaths, err := filepath.Glob(expandedPattern)
if err != nil {
return err
}
// Load files iteratively
for _, filepath := range filepaths {
if err := c.LoadFile(filepath); err != nil {
logger.Logger.Warnf("Cannot include %q: %v", filepath, err)
}
}
if c.ASSHBinaryPath != "" {
path, err := utils.ExpandUser(c.ASSHBinaryPath)
if err != nil {
return err
}
asshBinaryPath = path
}
return nil
}
// sortedNames returns the host names sorted alphabetically
func (c *Config) sortedNames() []string {
names := sort.StringSlice{}
for key := range c.Hosts {
names = append(names, key)
}
sort.Sort(names)
return names
}
// Validate checks for values errors
func (c *Config) Validate() []error {
errs := []error{}
for _, host := range c.Hosts {
errs = append(errs, host.Validate()...)
}
return errs
}
// ValidateSummary summaries Validate() errors slice
func (c *Config) ValidateSummary() error {
switch errs := c.Validate(); len(errs) {
case 0:
return nil
case 1:
return errs[0]
default:
errsStrings := []string{}
for _, err := range errs {
errsStrings = append(errsStrings, fmt.Sprintf("- %s", err.Error()))
}
return fmt.Errorf("multiple errors:\n%s", strings.Join(errsStrings, "\n"))
}
}
// WriteSSHConfigTo returns a .ssh/config valid file containing assh configuration
func (c *Config) WriteSSHConfigTo(w io.Writer) error {
header := strings.TrimSpace(`
# This file was automatically generated by assh v%VERSION
# on %BUILD_DATE, based on ~/.ssh/assh.yml
#
# more info: https://github.com/moul/advanced-ssh-config
`)
header = strings.Replace(header, "%VERSION", version.VERSION, -1)
header = strings.Replace(header, "%BUILD_DATE", time.Now().Format("2006-01-02 15:04:05 -0700 MST"), -1)
fmt.Fprintln(w, header)
// FIXME: add version
fmt.Fprintln(w)
fmt.Fprintln(w, "# host-based configuration")
for _, name := range c.sortedNames() {
host := c.Hosts[name]
computedHost, err := computeHost(host, c, name, false)
if err != nil {
return err
}
if err = computedHost.WriteSSHConfigTo(w); err != nil {
return err
}
fmt.Fprintln(w)
}
fmt.Fprintln(w, "# global configuration")
c.Defaults.name = "*"
return c.Defaults.WriteSSHConfigTo(w)
}
// SSHConfigPath returns the ~/.ssh/config file path
func (c *Config) SSHConfigPath() string { return c.sshConfigPath }
// New returns an instantiated Config object
func New() *Config {
var config Config
config.Hosts = make(map[string]*Host)
config.Templates = make(map[string]*Host)
config.includedFiles = make(map[string]bool)
config.sshConfigPath = defaultSSHConfigPath
config.ASSHKnownHostFile = "~/.ssh/assh_known_hosts"
config.ASSHBinaryPath = ""
return &config
}
// Open parses a configuration file and returns a *Config object
func Open(path string) (*Config, error) {
config := New()
err := config.LoadFile(path)
if err != nil {
return nil, err
}
return config, nil
}