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Copy pathproxy_headers.go
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132 lines (120 loc) · 4.25 KB
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// Copyright © 2020 The Things Network Foundation, The Things Industries B.V.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package webmiddleware
import (
"fmt"
"net"
"net/http"
"regexp"
"strings"
)
const (
headerForwarded = "Forwarded"
headerXForwardedFor = "X-Forwarded-For"
headerXForwardedHost = "X-Forwarded-Host"
headerXForwardedProto = "X-Forwarded-Proto" // We don't support non-standard headers such as Front-End-Https, X-Forwarded-Ssl, X-Url-Scheme.
headerXRealIP = "X-Real-IP"
headerXForwardedClientCert = "X-Forwarded-Client-Cert" // Envoy mTLS.
headerXForwardedTLSClientCert = "X-Forwarded-Tls-Client-Cert" // Traefik mTLS.
headerXForwardedTLSClientCertInfo = "X-Forwarded-Tls-Client-Cert-Info" // Traefik mTLS.
schemeHTTP = "http"
schemeHTTPS = "https"
)
var (
proxyHeaders = []string{
headerForwarded,
headerXForwardedFor, headerXForwardedHost, headerXForwardedProto,
headerXForwardedClientCert,
headerXForwardedTLSClientCert, headerXForwardedTLSClientCertInfo,
headerXRealIP,
}
forwardedForRegex = regexp.MustCompile(`(?i)(?:for=)([^(;|,| )]+)`)
forwardedHostRegex = regexp.MustCompile(`(?i)(?:host=)([^(;|,| )]+)`)
forwardedProtoRegex = regexp.MustCompile(`(?i)(?:proto=)(https|http)`)
)
// ProxyConfiguration is the configuration for the ProxyHeaders middleware.
type ProxyConfiguration struct {
Trusted []*net.IPNet
}
func (c ProxyConfiguration) trustedIP(ip net.IP) bool {
for _, ipNet := range c.Trusted {
if ipNet.Contains(ip) {
return true
}
}
return false
}
// ParseAndAddTrusted parses a list of CIDRs and adds them to the list of trusted ranges.
func (c *ProxyConfiguration) ParseAndAddTrusted(cidrs ...string) error {
for _, cidr := range cidrs {
_, net, err := net.ParseCIDR(cidr)
if err != nil {
return err
}
c.Trusted = append(c.Trusted, net)
}
return nil
}
// ProxyHeaders processes proxy headers for trusted proxies.
func ProxyHeaders(config ProxyConfiguration) MiddlewareFunc {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
remoteIP, _, err := net.SplitHostPort(r.RemoteAddr)
if err != nil {
// The *http.Server should have set r.RemoteAddr to "IP:port".
panic(fmt.Errorf("invalid RemoteAddr %q in *http.Request: %w", r.RemoteAddr, err))
}
if config.trustedIP(net.ParseIP(remoteIP)) {
// We trust the proxy, so we parse the headers if present.
forwardedFor, forwardedScheme, forwardedHost := parseForwardedHeaders(r.Header)
if forwardedFor != "" {
r.Header.Set(headerXRealIP, forwardedFor)
}
if forwardedScheme != "" {
r.URL.Scheme = forwardedScheme
}
if forwardedHost != "" {
r.URL.Host = forwardedHost
}
} else {
// We don't trust the proxy, remove its headers.
for _, header := range proxyHeaders {
r.Header.Del(header)
}
r.Header.Set(headerXRealIP, remoteIP)
}
next.ServeHTTP(w, r)
})
}
}
func parseForwardedHeaders(h http.Header) (forwardedFor, forwardedScheme, forwardedHost string) {
if xForwardedProto := h.Get(headerXForwardedProto); xForwardedProto != "" {
forwardedScheme = xForwardedProto
}
if xForwardedHost := h.Get(headerXForwardedHost); xForwardedHost != "" {
forwardedHost = xForwardedHost
}
if forwarded := h.Get(headerForwarded); forwarded != "" {
if match := forwardedForRegex.FindStringSubmatch(forwarded); len(match) > 1 {
forwardedFor = strings.ToLower(match[1])
}
if match := forwardedProtoRegex.FindStringSubmatch(forwarded); len(match) > 1 {
forwardedScheme = strings.ToLower(match[1])
}
if match := forwardedHostRegex.FindStringSubmatch(forwarded); len(match) > 1 {
forwardedHost = strings.ToLower(match[1])
}
}
return forwardedFor, forwardedScheme, forwardedHost
}