first release

2026-09-18 13:05:49 +08:00
commit b327bc1230
123 changed files with 30003 additions and 0 deletions
@@ -0,0 +1,208 @@
+package auth
+
+import (
+	"context"
+	"crypto/hmac"
+	"crypto/pbkdf2"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/subtle"
+	"database/sql"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	iterations = 210_000
+	keyLen     = 32
+	saltLen    = 16
+)
+
+var ErrInvalidCredentials = errors.New("用户名或密码错误")
+
+// HashPassword 使用 PBKDF2-SHA256 生成口令摘要。
+func HashPassword(password string) (string, error) {
+	salt := make([]byte, saltLen)
+	if _, err := rand.Read(salt); err != nil {
+		return "", err
+	}
+	dk, err := pbkdf2.Key(sha256.New, password, salt, iterations, keyLen)
+	if err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("pbkdf2$sha256$%d$%s$%s", iterations, b64(salt), b64(dk)), nil
+}
+
+func VerifyPassword(encoded, password string) bool {
+	parts := strings.Split(encoded, "$")
+	if len(parts) != 5 || parts[0] != "pbkdf2" {
+		return false
+	}
+	iter, err := strconv.Atoi(parts[2])
+	if err != nil {
+		return false
+	}
+	salt, err := unb64(parts[3])
+	if err != nil {
+		return false
+	}
+	want, err := unb64(parts[4])
+	if err != nil {
+		return false
+	}
+	got, err := pbkdf2.Key(sha256.New, password, salt, iter, len(want))
+	if err != nil {
+		return false
+	}
+	return subtle.ConstantTimeCompare(got, want) == 1
+}
+
+func b64(b []byte) string            { return base64.RawStdEncoding.EncodeToString(b) }
+func unb64(s string) ([]byte, error) { return base64.RawStdEncoding.DecodeString(s) }
+
+type User struct {
+	ID          int64
+	Username    string
+	DisplayName string
+	Hash        string
+}
+
+type Store struct {
+	DB     *sql.DB
+	Secret []byte
+	Days   int
+}
+
+// Authenticate 校验用户口令。
+func (s *Store) Authenticate(ctx context.Context, username, password string) (*User, error) {
+	var u User
+	err := s.DB.QueryRowContext(ctx, `SELECT id, username, COALESCE(display_name,''), password_hash
+		FROM users WHERE username=$1`, username).Scan(&u.ID, &u.Username, &u.DisplayName, &u.Hash)
+	if errors.Is(err, sql.ErrNoRows) {
+		return nil, ErrInvalidCredentials
+	}
+	if err != nil {
+		return nil, err
+	}
+	if !VerifyPassword(u.Hash, password) {
+		return nil, ErrInvalidCredentials
+	}
+	if _, err := s.DB.ExecContext(ctx, `UPDATE users SET last_login_at=now() WHERE id=$1`, u.ID); err != nil {
+		return nil, err
+	}
+	return &u, nil
+}
+
+// EnsureDefaultUser 在没有任何用户时创建初始管理员。
+func (s *Store) EnsureDefaultUser(ctx context.Context, username, password string) (bool, error) {
+	var n int
+	if err := s.DB.QueryRowContext(ctx, `SELECT count(*) FROM users`).Scan(&n); err != nil {
+		return false, err
+	}
+	if n > 0 {
+		return false, nil
+	}
+	hash, err := HashPassword(password)
+	if err != nil {
+		return false, err
+	}
+	if _, err := s.DB.ExecContext(ctx, `INSERT INTO users (username, password_hash, display_name)
+		VALUES ($1,$2,$3)`, username, hash, "站长"); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func (s *Store) ChangePassword(ctx context.Context, userID int64, current, next string) error {
+	var hash string
+	if err := s.DB.QueryRowContext(ctx, `SELECT password_hash FROM users WHERE id=$1`, userID).Scan(&hash); err != nil {
+		return err
+	}
+	if !VerifyPassword(hash, current) {
+		return ErrInvalidCredentials
+	}
+	nh, err := HashPassword(next)
+	if err != nil {
+		return err
+	}
+	_, err = s.DB.ExecContext(ctx, `UPDATE users SET password_hash=$1 WHERE id=$2`, nh, userID)
+	return err
+}
+
+// ErrUsernameTaken 表示新用户名已被占用。
+var ErrUsernameTaken = errors.New("用户名已被占用")
+
+// ChangeUsername 校验口令后改名。
+// 会话 cookie 认的是 id 与口令摘要（都不含用户名），所以改名不会把当前登录踢掉。
+func (s *Store) ChangeUsername(ctx context.Context, userID int64, current, name string) error {
+	var hash string
+	if err := s.DB.QueryRowContext(ctx, `SELECT password_hash FROM users WHERE id=$1`, userID).Scan(&hash); err != nil {
+		return err
+	}
+	if !VerifyPassword(hash, current) {
+		return ErrInvalidCredentials
+	}
+	var taken bool
+	if err := s.DB.QueryRowContext(ctx,
+		`SELECT EXISTS(SELECT 1 FROM users WHERE username=$1 AND id<>$2)`, name, userID).Scan(&taken); err != nil {
+		return err
+	}
+	if taken {
+		return ErrUsernameTaken
+	}
+	_, err := s.DB.ExecContext(ctx, `UPDATE users SET username=$1 WHERE id=$2`, name, userID)
+	return err
+}
+
+// UserByID 读取用户；用于每次请求还原登录态。
+func (s *Store) UserByID(ctx context.Context, id int64) (*User, error) {
+	var u User
+	err := s.DB.QueryRowContext(ctx, `SELECT id, username, COALESCE(display_name,''), password_hash
+		FROM users WHERE id=$1`, id).Scan(&u.ID, &u.Username, &u.DisplayName, &u.Hash)
+	if err != nil {
+		return nil, err
+	}
+	return &u, nil
+}
+
+// 会话令牌 = expiry|uid|hmac(uid|expiry|口令摘要前缀)，口令变更即自动失效。
+func (s *Store) SignToken(userID int64, hash string) string {
+	exp := time.Now().AddDate(0, 0, s.Days).Unix()
+	payload := fmt.Sprintf("%d|%d", userID, exp)
+	return payload + "|" + s.mac(payload, hash)
+}
+
+func (s *Store) ParseToken(token, hash string) (int64, bool) {
+	parts := strings.Split(token, "|")
+	if len(parts) != 3 {
+		return 0, false
+	}
+	uid, err1 := strconv.ParseInt(parts[0], 10, 64)
+	exp, err2 := strconv.ParseInt(parts[1], 10, 64)
+	if err1 != nil || err2 != nil || time.Now().Unix() > exp {
+		return 0, false
+	}
+	if !hmac.Equal([]byte(parts[2]), []byte(s.mac(parts[0]+"|"+parts[1], hash))) {
+		return 0, false
+	}
+	return uid, true
+}
+
+func (s *Store) mac(payload, hash string) string {
+	m := hmac.New(sha256.New, s.Secret)
+	m.Write([]byte(payload))
+	// 混入口令摘要，改密后旧 cookie 立即作废
+	m.Write([]byte("|" + hash[:min(len(hash), 16)]))
+	return b64(m.Sum(nil))
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}