2020-10-24 19:15:32 +00:00
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package gemini
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2020-09-25 22:53:20 +00:00
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import (
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"bufio"
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"crypto/sha512"
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"crypto/x509"
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"fmt"
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"io"
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2020-09-26 03:06:54 +00:00
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"os"
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"path/filepath"
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2020-11-06 03:30:13 +00:00
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"strconv"
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2020-09-25 22:53:20 +00:00
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"strings"
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)
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2020-11-01 02:34:51 +00:00
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// Trust represents the trustworthiness of a certificate.
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type Trust int
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const (
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TrustNone Trust = iota // The certificate is not trusted.
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TrustOnce // The certificate is trusted once.
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TrustAlways // The certificate is trusted always.
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)
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2020-09-26 00:22:48 +00:00
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// KnownHosts represents a list of known hosts.
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2020-09-27 18:18:30 +00:00
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// The zero value for KnownHosts is an empty list ready to use.
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type KnownHosts struct {
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hosts map[string]Fingerprint
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file *os.File
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}
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2020-10-12 20:56:26 +00:00
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// LoadDefault loads the known hosts from the default known hosts path, which is
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2020-09-28 02:19:24 +00:00
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// $XDG_DATA_HOME/gemini/known_hosts.
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2020-09-26 17:35:56 +00:00
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// It creates the path and any of its parent directories if they do not exist.
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// KnownHosts will append to the file whenever a certificate is added.
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func (k *KnownHosts) LoadDefault() error {
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path, err := defaultKnownHostsPath()
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if err != nil {
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return err
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}
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return k.Load(path)
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}
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2020-10-12 20:56:26 +00:00
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// Load loads the known hosts from the provided path.
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// It creates the path and any of its parent directories if they do not exist.
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// KnownHosts will append to the file whenever a certificate is added.
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func (k *KnownHosts) Load(path string) error {
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if dir := filepath.Dir(path); dir != "." {
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err := os.MkdirAll(dir, 0755)
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if err != nil {
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return err
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}
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}
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f, err := os.OpenFile(path, os.O_CREATE|os.O_RDONLY, 0644)
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if err != nil {
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return err
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}
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k.Parse(f)
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f.Close()
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// Open the file for append-only use
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f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
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if err != nil {
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return err
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}
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k.file = f
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return nil
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}
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// Add adds a certificate to the list of known hosts.
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// If KnownHosts was loaded from a file, Add will append to the file.
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2020-09-27 20:06:17 +00:00
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func (k *KnownHosts) Add(hostname string, cert *x509.Certificate) {
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k.add(hostname, cert, true)
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}
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2020-09-26 00:22:48 +00:00
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2020-10-13 23:54:48 +00:00
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// AddTemporary adds a certificate to the list of known hosts
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// without writing it to the known hosts file.
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2020-09-27 21:41:41 +00:00
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func (k *KnownHosts) AddTemporary(hostname string, cert *x509.Certificate) {
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k.add(hostname, cert, false)
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}
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func (k *KnownHosts) add(hostname string, cert *x509.Certificate, write bool) {
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if k.hosts == nil {
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k.hosts = map[string]Fingerprint{}
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}
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fingerprint := NewFingerprint(cert)
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k.hosts[hostname] = fingerprint
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// Append to the file
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if write && k.file != nil {
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appendKnownHost(k.file, hostname, fingerprint)
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}
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2020-09-27 21:41:41 +00:00
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}
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2020-11-05 20:27:12 +00:00
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// Lookup returns the fingerprint of the certificate corresponding to
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// the given hostname.
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func (k *KnownHosts) Lookup(hostname string) (Fingerprint, bool) {
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c, ok := k.hosts[hostname]
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return c, ok
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2020-09-26 17:27:03 +00:00
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}
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// Parse parses the provided reader and adds the parsed known hosts to the list.
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// Invalid lines are ignored.
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func (k *KnownHosts) Parse(r io.Reader) {
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if k.hosts == nil {
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k.hosts = map[string]Fingerprint{}
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}
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scanner := bufio.NewScanner(r)
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for scanner.Scan() {
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text := scanner.Text()
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parts := strings.Split(text, " ")
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2020-11-06 03:30:13 +00:00
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if len(parts) < 4 {
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continue
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}
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hostname := parts[0]
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algorithm := parts[1]
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2020-10-13 23:54:48 +00:00
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if algorithm != "SHA-512" {
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continue
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}
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fingerprint := parts[2]
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2020-11-06 03:30:13 +00:00
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expires, err := strconv.ParseInt(parts[3], 10, 0)
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if err != nil {
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continue
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}
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2020-11-05 20:27:12 +00:00
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k.hosts[hostname] = Fingerprint{
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Algorithm: algorithm,
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Hex: fingerprint,
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Expires: expires,
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}
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2020-09-25 22:53:20 +00:00
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}
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2020-09-26 00:55:37 +00:00
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}
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2020-09-25 22:53:20 +00:00
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2020-09-27 18:18:30 +00:00
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// Write writes the known hosts to the provided io.Writer.
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func (k *KnownHosts) Write(w io.Writer) {
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for h, c := range k.hosts {
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appendKnownHost(w, h, c)
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}
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}
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2020-11-05 20:27:12 +00:00
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func appendKnownHost(w io.Writer, hostname string, f Fingerprint) (int, error) {
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return fmt.Fprintf(w, "%s %s %s %d\n", hostname, f.Algorithm, f.Hex, f.Expires)
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}
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// Fingerprint represents a fingerprint using a certain algorithm.
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type Fingerprint struct {
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Algorithm string // fingerprint algorithm e.g. SHA-512
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Hex string // fingerprint in hexadecimal, with ':' between each octet
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Expires int64 // unix time of the fingerprint expiration date
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}
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// NewFingerprint returns the SHA-512 fingerprint of the provided certificate.
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func NewFingerprint(cert *x509.Certificate) Fingerprint {
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sum512 := sha512.Sum512(cert.Raw)
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2020-10-28 19:13:31 +00:00
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var b strings.Builder
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for i, f := range sum512 {
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if i > 0 {
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b.WriteByte(':')
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}
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2020-10-28 19:13:31 +00:00
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fmt.Fprintf(&b, "%02X", f)
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}
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return Fingerprint{
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Algorithm: "SHA-512",
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Hex: b.String(),
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2020-11-06 03:30:13 +00:00
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Expires: cert.NotAfter.Unix(),
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}
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2020-09-25 22:53:20 +00:00
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}
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2020-09-26 17:35:56 +00:00
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// defaultKnownHostsPath returns the default known_hosts path.
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// The default path is $XDG_DATA_HOME/gemini/known_hosts
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func defaultKnownHostsPath() (string, error) {
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dataDir, err := userDataDir()
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if err != nil {
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return "", err
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}
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return filepath.Join(dataDir, "gemini", "known_hosts"), nil
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}
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// userDataDir returns the user data directory.
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func userDataDir() (string, error) {
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dataDir, ok := os.LookupEnv("XDG_DATA_HOME")
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if ok {
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return dataDir, nil
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}
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home, err := os.UserHomeDir()
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if err != nil {
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return "", err
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}
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return filepath.Join(home, ".local", "share"), nil
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}
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