121 lines
3.6 KiB
Go
121 lines
3.6 KiB
Go
package client
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import (
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"crypto/sha256"
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"crypto/x509"
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"errors"
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"fmt"
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"strings"
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"time"
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"github.com/makeworld-the-better-one/amfora/config"
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)
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// TOFU implementation.
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// Stores cert hash and expiry for now, like Bombadillo.
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// There is ongoing TOFU discussion on the mailing list about better
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// ways to do this, and I will update this file once those are decided on.
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// Update: See #7 for some small improvements made.
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var ErrTofu = errors.New("server cert does not match TOFU database")
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var tofuStore = config.TofuStore
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// idKey returns the config/viper key needed to retrieve
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// a cert's ID / fingerprint.
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func idKey(domain string, port string) string {
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if port == "1965" || port == "" {
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return strings.ReplaceAll(domain, ".", "/")
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}
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return strings.ReplaceAll(domain, ".", "/") + ":" + port
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}
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func expiryKey(domain string, port string) string {
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if port == "1965" || port == "" {
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return strings.ReplaceAll(strings.TrimSuffix(domain, "."), ".", "/") + "/expiry"
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}
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return strings.ReplaceAll(strings.TrimSuffix(domain, "."), ".", "/") + "/expiry" + ":" + port
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}
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func loadTofuEntry(domain string, port string) (string, time.Time, error) {
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id := tofuStore.GetString(idKey(domain, port)) // Fingerprint
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if len(id) != 64 {
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// Not set, or invalid
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return "", time.Time{}, errors.New("not found")
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}
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expiry := tofuStore.GetTime(expiryKey(domain, port))
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if expiry.IsZero() {
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// Not set
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return id, time.Time{}, errors.New("not found")
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}
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return id, expiry, nil
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}
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// certID returns a generic string representing a cert or domain.
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func certID(cert *x509.Certificate) string {
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h := sha256.New()
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h.Write(cert.RawSubjectPublicKeyInfo) // Better than cert.Raw, see #7
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return fmt.Sprintf("%X", h.Sum(nil))
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}
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// origCertID uses cert.Raw, which was used in v1.0.0 of the app.
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func origCertID(cert *x509.Certificate) string {
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h := sha256.New()
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h.Write(cert.Raw)
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return fmt.Sprintf("%X", h.Sum(nil))
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}
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func saveTofuEntry(domain, port string, cert *x509.Certificate) {
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tofuStore.Set(idKey(domain, port), certID(cert))
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tofuStore.Set(expiryKey(domain, port), cert.NotAfter.UTC())
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tofuStore.WriteConfig()
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}
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// handleTofu is the abstracted interface for taking care of TOFU.
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// A cert is provided and storage, checking, etc, are taken care of.
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// It returns a bool indicating if the cert is valid according to
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// the TOFU database.
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// If false is returned, the connection should not go ahead.
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func handleTofu(domain, port string, cert *x509.Certificate) bool {
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id, expiry, err := loadTofuEntry(domain, port)
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if err != nil {
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// Cert isn't in database or data is malformed
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// So it can't be checked and anything is valid
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saveTofuEntry(domain, port, cert)
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return true
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}
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if certID(cert) == id {
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// Same cert as the one stored
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// Store expiry again in case it changed
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tofuStore.Set(expiryKey(domain, port), cert.NotAfter.UTC())
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tofuStore.WriteConfig()
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return true
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}
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if origCertID(cert) == id {
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// Valid but uses old ID type
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saveTofuEntry(domain, port, cert)
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return true
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}
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if time.Now().After(expiry) {
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// Old cert expired, so anything is valid
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saveTofuEntry(domain, port, cert)
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return true
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}
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return false
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}
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// ResetTofuEntry forces the cert passed to be valid, overwriting any previous TOFU entry.
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// The port string can be empty, to indicate port 1965.
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func ResetTofuEntry(domain, port string, cert *x509.Certificate) {
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saveTofuEntry(domain, port, cert)
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}
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// GetExpiry returns the stored expiry date for the given host.
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// The time will be empty (zero) if there is not expiry date stored for that host.
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func GetExpiry(domain, port string) time.Time {
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return tofuStore.GetTime(expiryKey(domain, port))
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}
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