72 lines
1.4 KiB
Go
72 lines
1.4 KiB
Go
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package realip
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import (
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"log"
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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 cidrs []*net.IPNet
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func init() {
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lancidrs := []string{
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"127.0.0.1/8", "10.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.168.0.0/16", "::1/128", "fc00::/7",
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}
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cidrs = make([]*net.IPNet, len(lancidrs))
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for i, it := range lancidrs {
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_, cidrnet, err := net.ParseCIDR(it)
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if err != nil {
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log.Fatalf("ParseCIDR error: %v", err) // assuming I did it right above
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}
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cidrs[i] = cidrnet
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}
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}
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func isLocalAddress(addr string) bool {
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for i := range cidrs {
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myaddr := net.ParseIP(addr)
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if cidrs[i].Contains(myaddr) {
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return true
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}
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}
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return false
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}
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// Request.RemoteAddress contains port, which we want to remove i.e.:
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// "[::1]:58292" => "[::1]"
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func ipAddrFromRemoteAddr(s string) string {
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idx := strings.LastIndex(s, ":")
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if idx == -1 {
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return s
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}
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return s[:idx]
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}
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// RealIP return client's real public IP address
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// from http request headers.
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func RealIP(r *http.Request) string {
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hdr := r.Header
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hdrRealIP := hdr.Get("X-Real-Ip")
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hdrForwardedFor := hdr.Get("X-Forwarded-For")
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if len(hdrForwardedFor) == 0 && len(hdrRealIP) == 0 {
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return ipAddrFromRemoteAddr(r.RemoteAddr)
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}
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// X-Forwarded-For is potentially a list of addresses separated with ","
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for _, addr := range strings.Split(hdrForwardedFor, ",") {
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// return first non-local address
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addr = strings.TrimSpace(addr)
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if len(addr) > 0 && !isLocalAddress(addr) {
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return addr
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}
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}
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return hdrRealIP
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}
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