UmputunandGitHub
89dc8ac6dd
* change go mod to 1.17 * update go-pgkz and transitive deps * bump examples to go-1.17 * bump deps
81 lines
2.2 KiB
Go
81 lines
2.2 KiB
Go
// Package realip extracts a real IP address from the request.
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package realip
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import (
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"bytes"
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"fmt"
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"net"
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"net/http"
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"strings"
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)
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type ipRange struct {
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start net.IP
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end net.IP
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}
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var privateRanges = []ipRange{
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{start: net.ParseIP("10.0.0.0"), end: net.ParseIP("10.255.255.255")},
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{start: net.ParseIP("100.64.0.0"), end: net.ParseIP("100.127.255.255")},
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{start: net.ParseIP("172.16.0.0"), end: net.ParseIP("172.31.255.255")},
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{start: net.ParseIP("192.0.0.0"), end: net.ParseIP("192.0.0.255")},
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{start: net.ParseIP("192.168.0.0"), end: net.ParseIP("192.168.255.255")},
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{start: net.ParseIP("198.18.0.0"), end: net.ParseIP("198.19.255.255")},
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}
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// Get returns real ip from the given request
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func Get(r *http.Request) (string, error) {
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for _, h := range []string{"X-Forwarded-For", "X-Real-Ip"} {
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addresses := strings.Split(r.Header.Get(h), ",")
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// march from right to left until we get a public address
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// that will be the address right before our proxy.
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for i := len(addresses) - 1; i >= 0; i-- {
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ip := strings.TrimSpace(addresses[i])
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realIP := net.ParseIP(ip)
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if !realIP.IsGlobalUnicast() || isPrivateSubnet(realIP) {
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continue
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}
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return ip, nil
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}
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}
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// X-Forwarded-For header set but parsing failed above
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if r.Header.Get("X-Forwarded-For") != "" {
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return "", fmt.Errorf("no valid ip found")
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}
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// get IP from RemoteAddr
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ip, _, err := net.SplitHostPort(r.RemoteAddr)
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if err != nil {
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return "", fmt.Errorf("can't parse ip %q: %w", r.RemoteAddr, err)
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}
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if netIP := net.ParseIP(ip); netIP == nil {
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return "", fmt.Errorf("no valid ip found")
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}
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return ip, nil
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}
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// inRange - check to see if a given ip address is within a range given
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func inRange(r ipRange, ipAddress net.IP) bool {
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// strcmp type byte comparison
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if bytes.Compare(ipAddress, r.start) >= 0 && bytes.Compare(ipAddress, r.end) < 0 {
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return true
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}
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return false
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}
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// isPrivateSubnet - check to see if this ip is in a private subnet
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func isPrivateSubnet(ipAddress net.IP) bool {
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if ipCheck := ipAddress.To4(); ipCheck != nil {
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for _, r := range privateRanges {
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// check if this ip is in a private range
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if inRange(r, ipAddress) {
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return true
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}
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}
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}
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return false
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}
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