use client-IP if none was provided (fix #2)

.gitignore

@@ -1,4 +1,5 @@
 **/geoip-lookup-service
 **/geoip-lookup
 **/main
-build/
+build/
+.idea/

README.md

@@ -89,6 +89,9 @@ curl "http://127.0.0.1:10069/?ip=8.8.8.8&lookup=country&filter=country.names.en"
 
 curl "http://127.0.0.1:10069/?ip=8.8.8.8&lookup=city&filter=location"
 > {"accuracy_radius":1000,"latitude":37.751,"longitude":-97.822,"time_zone":"America/Chicago"}
+
+# listen on all external IPs
+./geoip_lookup_service -l 0.0.0.0 -p 10069 ...
 ```
 
 ----

cnf/main.go

@@ -1,3 +1,3 @@
 package cnf
 
-const VERSION = 1.0
+const VERSION = 1.1

main/server.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -39,12 +40,53 @@ func returnResult(w http.ResponseWriter, data interface{}, logPrefix string) {
 	}
 }
 
+func getClientIP(r *http.Request) (string, error) {
+	fwdIPs := strings.Split(r.Header.Get("X-Forwarded-For"), ",")
+	if len(fwdIPs) > 0 {
+		netIP := net.ParseIP(fwdIPs[len(fwdIPs)-1])
+		if netIP != nil {
+			return netIP.String(), nil
+		}
+	}
+
+	realIP := r.Header.Get("X-Real-IP")
+	if realIP != "" {
+		netIP := net.ParseIP(realIP)
+		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 geoIpLookup(w http.ResponseWriter, r *http.Request) {
 	ipStr := r.URL.Query().Get("ip")
 	lookupStr := r.URL.Query().Get("lookup")
 	filterStr := r.URL.Query().Get("filter")
 	logPrefix := fmt.Sprintf("IP: '%v', Lookup: '%v', Filter: '%v'", ipStr, lookupStr, filterStr)
 
+	if ipStr == "" {
+		clientIpStr, err := getClientIP(r)
+		if err == nil {
+			ipStr = clientIpStr
+		}
+	}
+
 	if lookupStr == "" || ipStr == "" {
 		errorResponse(w, "Either 'lookup' or 'ip' were not provided")
 		return

script/build_all_bin.sh

@@ -8,7 +8,7 @@ VERSION="$(cat "../cnf/main.go" | grep VERSION | cut -d '=' -f2 | tr -d ' ')"
 
 mkdir -p "../build"
 
-rm ../build/*
+rm -f ../build/*
 
 function compile() {
     os="$1" arch="$2"
@@ -30,6 +30,7 @@ compile "linux" "amd64"
 compile "linux" "arm"
 compile "linux" "arm64"
 
+# untested
 compile "freebsd" "386"
 compile "freebsd" "amd64"
 compile "freebsd" "arm"
@@ -41,6 +42,5 @@ compile "openbsd" "arm"
 compile "darwin" "amd64"
 compile "darwin" "arm64"
 
-# untested
 compile "windows" "386"
 compile "windows" "amd64"