refactor the password hashing / password autoupgrade system

irc/legacy.go

@@ -0,0 +1,72 @@
+// Copyright (c) 2018 Shivaram Lingamneni
+
+package irc
+
+import (
+	"encoding/base64"
+	"errors"
+	"fmt"
+
+	"github.com/tidwall/buntdb"
+	"golang.org/x/crypto/bcrypt"
+)
+
+var (
+	errInvalidPasswordHash = errors.New("invalid password hash")
+)
+
+// Decode a hashed passphrase as it would appear in a config file,
+// retaining compatibility with old versions of `oragono genpasswd`
+// that used to apply a redundant layer of base64
+func decodeLegacyPasswordHash(hash string) ([]byte, error) {
+	// a correctly formatted bcrypt hash is 60 bytes of printable ASCII
+	if len(hash) == 80 {
+		// double-base64, remove the outer layer:
+		return base64.StdEncoding.DecodeString(hash)
+	} else if len(hash) == 60 {
+		return []byte(hash), nil
+	} else {
+		return nil, errInvalidPasswordHash
+	}
+}
+
+// helper to check a version 0 password hash, with global and per-passphrase salts
+func checkLegacyPasswordV0(hashedPassword, globalSalt, passphraseSalt []byte, passphrase string) error {
+	var assembledPasswordBytes []byte
+	assembledPasswordBytes = append(assembledPasswordBytes, globalSalt...)
+	assembledPasswordBytes = append(assembledPasswordBytes, '-')
+	assembledPasswordBytes = append(assembledPasswordBytes, passphraseSalt...)
+	assembledPasswordBytes = append(assembledPasswordBytes, '-')
+	assembledPasswordBytes = append(assembledPasswordBytes, []byte(passphrase)...)
+	return bcrypt.CompareHashAndPassword(hashedPassword, assembledPasswordBytes)
+}
+
+// checks a version 0 password hash; if successful, upgrades the database entry to version 1
+func handleLegacyPasswordV0(server *Server, account string, credentials AccountCredentials, passphrase string) (err error) {
+	var globalSaltString string
+	err = server.store.View(func(tx *buntdb.Tx) (err error) {
+		globalSaltString, err = tx.Get("crypto.salt")
+		return err
+	})
+	if err != nil {
+		return err
+	}
+	globalSalt, err := base64.StdEncoding.DecodeString(globalSaltString)
+	if err != nil {
+		return err
+	}
+
+	err = checkLegacyPasswordV0(credentials.PassphraseHash, globalSalt, credentials.PassphraseSalt, passphrase)
+	if err != nil {
+		// invalid password
+		return err
+	}
+
+	// upgrade credentials
+	err = server.accounts.setPassword(account, passphrase)
+	if err != nil {
+		server.logger.Error("internal", fmt.Sprintf("could not upgrade user password: %v", err))
+	}
+
+	return nil
+}