134 lines
2.9 KiB
Go
134 lines
2.9 KiB
Go
package middleware
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import (
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"context"
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"net/http"
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"strconv"
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"sync"
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"time"
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"github.com/gin-gonic/gin"
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"github.com/redis/go-redis/v9"
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)
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type rateLimitBucket struct {
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count int
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resetAt time.Time
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lastSeen time.Time
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}
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type rateLimiter struct {
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mu sync.Mutex
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limit int
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window time.Duration
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buckets map[string]rateLimitBucket
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}
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type redisRateLimiter struct {
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redis *redis.Client
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fallback *rateLimiter
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limit int
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window time.Duration
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}
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func RateLimitPerMinute(limit int, rdb *redis.Client) gin.HandlerFunc {
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if limit <= 0 {
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return func(c *gin.Context) {
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c.Next()
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}
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}
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limiter := &rateLimiter{
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limit: limit,
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window: time.Minute,
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buckets: make(map[string]rateLimitBucket),
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}
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if rdb != nil {
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return (&redisRateLimiter{
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redis: rdb,
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fallback: limiter,
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limit: limit,
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window: time.Minute,
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}).handle
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}
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return limiter.handle
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}
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func (l *redisRateLimiter) handle(c *gin.Context) {
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now := time.Now()
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key := c.ClientIP()
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allowed, resetAt, err := l.allow(c.Request.Context(), key, now)
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if err != nil {
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allowed, resetAt = l.fallback.allow(key, now)
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}
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if !allowed {
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writeRateLimited(c, now, resetAt)
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return
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}
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c.Next()
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}
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func (l *rateLimiter) handle(c *gin.Context) {
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now := time.Now()
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key := c.ClientIP()
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allowed, resetAt := l.allow(key, now)
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if !allowed {
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writeRateLimited(c, now, resetAt)
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return
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}
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c.Next()
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}
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func (l *redisRateLimiter) allow(ctx context.Context, key string, now time.Time) (bool, time.Time, error) {
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windowSeconds := int64(l.window / time.Second)
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windowID := now.Unix() / windowSeconds
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redisKey := "rate_limit:" + key + ":" + strconv.FormatInt(windowID, 10)
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count, err := l.redis.Incr(ctx, redisKey).Result()
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if err != nil {
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return false, time.Time{}, err
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}
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if count == 1 {
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_ = l.redis.Expire(ctx, redisKey, 2*l.window).Err()
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}
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resetAt := time.Unix((windowID+1)*windowSeconds, 0)
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return count <= int64(l.limit), resetAt, nil
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}
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func (l *rateLimiter) allow(key string, now time.Time) (bool, time.Time) {
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l.mu.Lock()
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defer l.mu.Unlock()
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l.cleanup(now)
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bucket := l.buckets[key]
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if bucket.resetAt.IsZero() || !now.Before(bucket.resetAt) {
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bucket = rateLimitBucket{resetAt: now.Add(l.window)}
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}
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bucket.count++
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bucket.lastSeen = now
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l.buckets[key] = bucket
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return bucket.count <= l.limit, bucket.resetAt
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}
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func (l *rateLimiter) cleanup(now time.Time) {
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for key, bucket := range l.buckets {
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if now.Sub(bucket.lastSeen) > 2*l.window {
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delete(l.buckets, key)
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}
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}
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}
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func retryAfterSeconds(now time.Time, resetAt time.Time) string {
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seconds := int(resetAt.Sub(now).Seconds())
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if seconds < 1 {
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seconds = 1
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}
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return strconv.Itoa(seconds)
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}
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func writeRateLimited(c *gin.Context, now time.Time, resetAt time.Time) {
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c.Header("Retry-After", retryAfterSeconds(now, resetAt))
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c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
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"code": "rate_limited",
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"message": "请求过于频繁，请稍后再试",
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})
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}
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