初始提交：姜十三论坛 Jiang13 Forum

轻量自用论坛，Go 单二进制 + React SPA 内嵌 + SQLite。

Co-authored-by: Cursor <cursoragent@cursor.com>

service/common.go

@@ -0,0 +1,109 @@
+package service
+
+import (
+	"errors"
+	"regexp"
+	"strings"
+	"sync"
+	"unicode/utf8"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+var (
+	ErrUserExists       = errors.New("用户名已存在")
+	ErrInvalidCred      = errors.New("用户名或密码错误")
+	ErrUserBanned       = errors.New("账号已被禁言")
+	ErrWeakPassword     = errors.New("密码至少 6 位")
+	ErrInvalidUsername  = errors.New("用户名 3-32 位字母数字下划线")
+	ErrPostNotFound     = errors.New("帖子不存在")
+	ErrCommentNotFound  = errors.New("评论不存在")
+	ErrPermissionDenied = errors.New("无权操作")
+	ErrBoardNotFound    = errors.New("板块不存在")
+)
+
+var usernameRe = regexp.MustCompile(`^[a-zA-Z0-9_]{3,32}$`)
+
+// HashPassword 使用 bcrypt 加密密码
+func HashPassword(password string) (string, error) {
+	bytes, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	return string(bytes), err
+}
+
+// CheckPassword 校验密码
+func CheckPassword(hash, password string) bool {
+	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(password)) == nil
+}
+
+// ValidateUsername 校验用户名格式
+func ValidateUsername(username string) error {
+	if !usernameRe.MatchString(username) {
+		return ErrInvalidUsername
+	}
+	return nil
+}
+
+// ValidatePassword 校验密码强度
+func ValidatePassword(password string) error {
+	if utf8.RuneCountInString(password) < 6 {
+		return ErrWeakPassword
+	}
+	return nil
+}
+
+// SensitiveFilter 敏感词过滤器
+type SensitiveFilter struct {
+	mu    sync.RWMutex
+	words []string
+}
+
+func NewSensitiveFilter() *SensitiveFilter {
+	return &SensitiveFilter{
+		words: []string{"违禁词示例", "广告刷单"},
+	}
+}
+
+// LoadFromFile 从配置文件加载敏感词，每行一个词
+func (f *SensitiveFilter) LoadFromFile(path string) {
+	data, err := osReadFile(path)
+	if err != nil {
+		return
+	}
+	lines := strings.Split(string(data), "\n")
+	var words []string
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line != "" && !strings.HasPrefix(line, "#") {
+			words = append(words, line)
+		}
+	}
+	if len(words) > 0 {
+		f.mu.Lock()
+		f.words = words
+		f.mu.Unlock()
+	}
+}
+
+func (f *SensitiveFilter) Filter(text string) string {
+	f.mu.RLock()
+	defer f.mu.RUnlock()
+	result := text
+	for _, w := range f.words {
+		if w == "" {
+			continue
+		}
+		replacement := strings.Repeat("*", utf8.RuneCountInString(w))
+		result = strings.ReplaceAll(result, w, replacement)
+	}
+	return result
+}
+
+// osReadFile 避免循环依赖，简单封装
+func osReadFile(path string) ([]byte, error) {
+	return readFile(path)
+}
+
+// readFile 由 filter_io.go 实现
+var readFile = func(path string) ([]byte, error) {
+	return nil, errors.New("not implemented")
+}