43 lines
1.4 KiB
Go
43 lines
1.4 KiB
Go
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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)
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// HTTPMiddleware wraps next with per-client-IP rate limiting, returning 429
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// for requests over the limit. realIPHeader (e.g. "X-Forwarded-For"), if
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// non-empty, is trusted for the client IP instead of RemoteAddr — only set
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// this when the server is genuinely behind a reverse proxy that sets it;
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// trusting it otherwise lets any client spoof their rate-limit identity.
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func (l *Limiter) HTTPMiddleware(realIPHeader string, next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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ip := ClientIP(r, realIPHeader)
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if !l.Allow(ip) {
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w.Header().Set("Retry-After", "60")
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http.Error(w, "rate limit exceeded, try again shortly", http.StatusTooManyRequests)
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return
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}
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next.ServeHTTP(w, r)
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})
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}
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// ClientIP resolves the request's client IP the same way HTTPMiddleware
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// does, for callers that need it outside a rate-limit context (e.g. an IP
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// allowlist middleware). See HTTPMiddleware's doc comment for the
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// realIPHeader trust caveat.
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func ClientIP(r *http.Request, realIPHeader string) string {
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if realIPHeader != "" {
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if v := r.Header.Get(realIPHeader); v != "" {
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parts := strings.Split(v, ",")
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return strings.TrimSpace(parts[0])
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}
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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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