78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
package xff
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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 privateMasks = func() []net.IPNet {
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masks := []net.IPNet{}
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for _, cidr := range []string{"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "fc00::/7"} {
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_, net, err := net.ParseCIDR(cidr)
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if err != nil {
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panic(err)
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}
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masks = append(masks, *net)
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}
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return masks
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}()
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// IsPublicIP returns true if the given IP can be routed on the Internet
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func IsPublicIP(ip net.IP) bool {
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if !ip.IsGlobalUnicast() {
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return false
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}
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for _, mask := range privateMasks {
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if mask.Contains(ip) {
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return false
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}
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}
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return true
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}
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// Parse parses the value of the X-Forwarded-For Header and returns the IP address.
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func Parse(ipList string) string {
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for _, ip := range strings.Split(ipList, ",") {
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ip = strings.TrimSpace(ip)
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if IP := net.ParseIP(ip); IP != nil && IsPublicIP(IP) {
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return ip
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}
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}
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return ""
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}
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// GetRemoteAddr parses the given request, resolves the X-Forwarded-For header
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// and returns the resolved remote address.
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func GetRemoteAddr(r *http.Request) string {
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xff := r.Header.Get("X-Forwarded-For")
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var ip string
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if xff != "" {
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ip = Parse(xff)
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}
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_, oport, err := net.SplitHostPort(r.RemoteAddr)
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if err == nil && ip != "" {
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return net.JoinHostPort(ip, oport)
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}
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return r.RemoteAddr
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}
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// Handler is a middleware to update RemoteAdd from X-Fowarded-* Headers.
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func Handler(h http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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r.RemoteAddr = GetRemoteAddr(r)
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h.ServeHTTP(w, r)
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})
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}
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// HandlerFunc is a Martini compatible handler
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func HandlerFunc(w http.ResponseWriter, r *http.Request) {
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r.RemoteAddr = GetRemoteAddr(r)
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}
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// XFF is a Negroni compatible interface
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func XFF(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
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r.RemoteAddr = GetRemoteAddr(r)
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next(w, r)
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}
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