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package main
import (
"net"
"net/http"
"strings"
"sync"
"time"
)
type limiter struct {
mu sync.Mutex
hits map[string][]time.Time
max int
window time.Duration
}
func newLimiter(max int, window time.Duration) *limiter {
return &limiter{hits: map[string][]time.Time{}, max: max, window: window}
}
func (l *limiter) prune(key string, now time.Time) []time.Time {
cutoff := now.Add(-l.window)
kept := l.hits[key][:0]
for _, t := range l.hits[key] {
if t.After(cutoff) {
kept = append(kept, t)
}
}
if len(kept) == 0 {
delete(l.hits, key)
} else {
l.hits[key] = kept
}
if len(l.hits) > 10000 {
for k, v := range l.hits {
if !v[len(v)-1].After(cutoff) {
delete(l.hits, k)
}
}
}
return kept
}
func (l *limiter) blocked(key string) bool {
l.mu.Lock()
defer l.mu.Unlock()
return len(l.prune(key, time.Now())) >= l.max
}
func (l *limiter) fail(key string) {
l.mu.Lock()
defer l.mu.Unlock()
now := time.Now()
l.hits[key] = append(l.prune(key, now), now)
}
func clientIP(r *http.Request) string {
host, _, err := net.SplitHostPort(r.RemoteAddr)
if err != nil {
host = r.RemoteAddr
}
if ip := net.ParseIP(host); ip != nil && ip.IsLoopback() {
if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
hops := strings.Split(xff, ",")
return strings.TrimSpace(hops[len(hops)-1])
}
}
return host
}
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