62 lines
1.4 KiB
Go
62 lines
1.4 KiB
Go
// Package ratelimit provides a simple in-memory fixed-window limiter
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// keyed by client IP, used to protect authentication endpoints.
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package ratelimit
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import (
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"net"
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"net/http"
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"strings"
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"sync"
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"time"
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)
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// Limiter is a fixed-window, per-IP request limiter.
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type Limiter struct {
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mu sync.Mutex
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max int
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window time.Duration
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hits map[string]*hits
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}
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type hits struct {
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windowStart time.Time
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count int
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}
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// New returns a limiter allowing max requests per window per IP.
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func New(max int, window time.Duration) *Limiter {
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return &Limiter{max: max, window: window, hits: make(map[string]*hits)}
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}
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// Allow reports whether the request passes the limit, consuming one slot.
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func (l *Limiter) Allow(r *http.Request) bool {
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ip := ClientIP(r)
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now := time.Now()
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l.mu.Lock()
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defer l.mu.Unlock()
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h := l.hits[ip]
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if h == nil || now.Sub(h.windowStart) >= l.window {
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h = &hits{windowStart: now}
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l.hits[ip] = h
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}
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h.count++
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return h.count <= l.max
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}
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// ClientIP extracts the remote address, preferring X-Forwarded-For when
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// running behind a reverse proxy.
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func ClientIP(r *http.Request) string {
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if fwd := r.Header.Get("X-Forwarded-For"); fwd != "" {
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if i := strings.IndexByte(fwd, ','); i > 0 {
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return strings.TrimSpace(fwd[:i])
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}
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return strings.TrimSpace(fwd)
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}
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host, _, err := net.SplitHostPort(r.RemoteAddr)
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if err != nil {
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return r.RemoteAddr
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}
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return host
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}
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