This repository has been archived by the owner on Jul 12, 2023. It is now read-only.
/
realip.go
49 lines (42 loc) · 1.49 KB
/
realip.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
// Copyright 2021 the Exposure Notifications Verification Server authors
//
// 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 realip attempts to extract the real IP address from a service running
// behind a load balancer.
package realip
import (
"net/http"
"strings"
)
const headerKeyXForwardedFor = "X-Forwarded-For"
// FromGoogleCloud extracts the best real client IP address from the request,
// handling xff behind a load balancer. It returns the empty string if no real
// IP was found.
func FromGoogleCloud(r *http.Request) string {
if r == nil {
return ""
}
// Get the remote addr
ip := r.RemoteAddr
// Check if x-forwarded-for exists, the load balancer sets this, and last
// entry is the IP. We only check xff if there's at least two values to ensure
// that it was, in fact, behind a load balancer.
xff := r.Header.Get(headerKeyXForwardedFor)
if xff != "" {
parts := strings.Split(xff, ",")
if len(parts) > 1 {
ip = parts[len(parts)-1]
}
}
return strings.TrimSpace(ip)
}