54 lines
1.5 KiB
Go
54 lines
1.5 KiB
Go
package middleware
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// Ported from Goji's middleware, source:
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// https://github.com/zenazn/goji/tree/master/web/middleware
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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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var trueClientIP = http.CanonicalHeaderKey("True-Client-IP")
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var xForwardedFor = http.CanonicalHeaderKey("X-Forwarded-For")
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var xRealIP = http.CanonicalHeaderKey("X-Real-IP")
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// RealIP is a middleware that sets a http.Request's RemoteAddr to the results
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// of parsing either the True-Client-IP, X-Real-IP or the X-Forwarded-For headers
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// (in that order).
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//
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// Deprecated: RealIP is vulnerable to IP spoofing — it mutates r.RemoteAddr
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// to the leftmost X-Forwarded-For value, or to True-Client-IP / X-Real-IP
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// whether or not your infrastructure actually sets them. See
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// GHSA-3fxj-6jh8-hvhx, GHSA-rjr7-jggh-pgcp, GHSA-9g5q-2w5x-hmxf.
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//
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// Use [ClientIPFromHeader], [ClientIPFromXFF], [ClientIPFromXFFTrustedProxies]
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// or [ClientIPFromRemoteAddr] and read the IP with [GetClientIP] instead.
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// These never mutate r.RemoteAddr.
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func RealIP(h http.Handler) http.Handler {
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fn := func(w http.ResponseWriter, r *http.Request) {
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if rip := realIP(r); rip != "" {
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r.RemoteAddr = rip
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}
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h.ServeHTTP(w, r)
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}
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return http.HandlerFunc(fn)
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}
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func realIP(r *http.Request) string {
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var ip string
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if tcip := r.Header.Get(trueClientIP); tcip != "" {
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ip = tcip
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} else if xrip := r.Header.Get(xRealIP); xrip != "" {
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ip = xrip
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} else if xff := r.Header.Get(xForwardedFor); xff != "" {
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ip, _, _ = strings.Cut(xff, ",")
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}
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if ip == "" || net.ParseIP(ip) == nil {
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return ""
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}
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return ip
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}
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