package git
import (
"bufio"
"io"
"net/url"
"os"
"path/filepath"
"regexp"
"strings"
"github.com/mitchellh/go-homedir"
)
var (
sshHostRE,
sshTokenRE *regexp.Regexp
)
func init() {
sshHostRE = regexp.MustCompile("(?i)^[ \t]*(host|hostname)[ \t]+(.+)$")
sshTokenRE = regexp.MustCompile(`%[%h]`)
}
// SSHAliasMap encapsulates the translation of SSH hostname aliases
type SSHAliasMap map[string]string
// Translator returns a function that applies hostname aliases to URLs
func (m SSHAliasMap) Translator() func(*url.URL) *url.URL {
return func(u *url.URL) *url.URL {
if u.Scheme != "ssh" {
return u
}
resolvedHost, ok := m[u.Hostname()]
if !ok {
return u
}
// FIXME: cleanup domain logic
if strings.EqualFold(u.Hostname(), "github.com") && strings.EqualFold(resolvedHost, "ssh.github.com") {
return u
}
newURL, _ := url.Parse(u.String())
newURL.Host = resolvedHost
return newURL
}
}
// ParseSSHConfig constructs a map of SSH hostname aliases based on user and
// system configuration files
func ParseSSHConfig() SSHAliasMap {
configFiles := []string{
"/etc/ssh_config",
"/etc/ssh/ssh_config",
}
if homedir, err := homedir.Dir(); err == nil {
userConfig := filepath.Join(homedir, ".ssh", "config")
configFiles = append([]string{userConfig}, configFiles...)
}
openFiles := make([]io.Reader, 0, len(configFiles))
for _, file := range configFiles {
f, err := os.Open(file)
if err != nil {
continue
}
defer f.Close()
openFiles = append(openFiles, f)
}
return sshParse(openFiles...)
}
func sshParse(r ...io.Reader) SSHAliasMap {
config := make(SSHAliasMap)
for _, file := range r {
_ = sshParseConfig(config, file)
}
return config
}
func sshParseConfig(c SSHAliasMap, file io.Reader) error {
hosts := []string{"*"}
scanner := bufio.NewScanner(file)
for scanner.Scan() {
line := scanner.Text()
match := sshHostRE.FindStringSubmatch(line)
if match == nil {
continue
}
names := strings.Fields(match[2])
if strings.EqualFold(match[1], "host") {
hosts = names
} else {
for _, host := range hosts {
for _, name := range names {
c[host] = sshExpandTokens(name, host)
}
}
}
}
return scanner.Err()
}
func sshExpandTokens(text, host string) string {
return sshTokenRE.ReplaceAllStringFunc(text, func(match string) string {
switch match {
case "%h":
return host
case "%%":
return "%"
}
return ""
})
}