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Golang get IP address from web HTTP request handler
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package main | |
import ( | |
"errors" | |
"log" | |
"net" | |
"net/http" | |
"strings" | |
) | |
// getIP returns the ip address from the http request | |
func getIP(r *http.Request) (string, error) { | |
ips := r.Header.Get("X-Forwarded-For") | |
splitIps := strings.Split(ips, ",") | |
if len(splitIps) > 0 { | |
// get last IP in list since ELB prepends other user defined IPs, meaning the last one is the actual client IP. | |
netIP := net.ParseIP(splitIps[len(splitIps)-1]) | |
if netIP != nil { | |
return netIP.String(), nil | |
} | |
} | |
ip, _, err := net.SplitHostPort(r.RemoteAddr) | |
if err != nil { | |
return "", err | |
} | |
netIP := net.ParseIP(ip) | |
if netIP != nil { | |
ip := netIP.String() | |
if ip == "::1" { | |
return "127.0.0.1", nil | |
} | |
return ip, nil | |
} | |
return "", errors.New("IP not found") | |
} | |
func handler(w http.ResponseWriter, r *http.Request) { | |
ip, err := getIP(r) | |
if err != nil { | |
w.WriteHeader(http.StatusInternalServerError) | |
return | |
} | |
w.WriteHeader(http.StatusOK) | |
w.Write([]byte(ip)) | |
} | |
func main() { | |
http.HandleFunc("/", handler) | |
log.Fatal(http.ListenAndServe(":8080", nil)) | |
} |
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Hi,
Thanks for this, it helped me for get IP.
it seems , the if condition in line 16 not needed as splitIps always greater than 1
and also i think in x-forwarded-for header the left most is the client IP