/
ssh.go
94 lines (82 loc) · 1.91 KB
/
ssh.go
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// Package ssh resolves local SSH hostname aliases.
package ssh
import (
"bufio"
"net/url"
"os/exec"
"strings"
"sync"
"github.com/cli/safeexec"
)
type Translator struct {
cacheMap map[string]string
cacheMu sync.RWMutex
sshPath string
sshPathErr error
sshPathMu sync.Mutex
sshConfig string
}
// NewTranslator initializes a new Translator instance.
func NewTranslator() *Translator {
return &Translator{}
}
// Translate applies applicable SSH hostname aliases to the specified URL and returns the resulting URL.
func (t *Translator) Translate(u *url.URL) *url.URL {
if u.Scheme != "ssh" {
return u
}
resolvedHost, err := t.resolve(u.Hostname())
if err != nil {
return u
}
if strings.EqualFold(resolvedHost, "ssh.github.com") {
resolvedHost = "github.com"
}
newURL, _ := url.Parse(u.String())
newURL.Host = resolvedHost
return newURL
}
func (t *Translator) resolve(hostname string) (string, error) {
t.cacheMu.RLock()
cached, cacheFound := t.cacheMap[strings.ToLower(hostname)]
t.cacheMu.RUnlock()
if cacheFound {
return cached, nil
}
var sshPath string
t.sshPathMu.Lock()
if t.sshPath == "" && t.sshPathErr == nil {
t.sshPath, t.sshPathErr = safeexec.LookPath("ssh")
}
if t.sshPathErr != nil {
defer t.sshPathMu.Unlock()
return t.sshPath, t.sshPathErr
}
sshPath = t.sshPath
t.sshPathMu.Unlock()
t.cacheMu.Lock()
defer t.cacheMu.Unlock()
sshArgs := []string{"-G", hostname}
if t.sshConfig != "" {
sshArgs = append(sshArgs, "-F", t.sshConfig)
}
sshCmd := exec.Command(sshPath, sshArgs...)
stdout, err := sshCmd.StdoutPipe()
if err != nil {
return "", err
}
if err := sshCmd.Start(); err != nil {
return "", err
}
var resolvedHost string
s := bufio.NewScanner(stdout)
for s.Scan() {
line := s.Text()
parts := strings.SplitN(line, " ", 2)
if len(parts) == 2 && parts[0] == "hostname" {
resolvedHost = parts[1]
}
}
_ = sshCmd.Wait()
return resolvedHost, nil
}