Add a header to change the which header we look for the remote IP

closes #3

main.go

@@ -15,6 +15,7 @@ type Configuration struct {
 	hostname string // Displayed Hostname
 	host     string // Listened Host
 	port     string // HTTP Port
+	ipheader string // Header to overwrite the remote IP
 	tls      bool   // TLS enabled
 	tlscert  string // TLS Cert Path
 	tlskey   string // TLS Cert Key Path
@@ -29,6 +30,9 @@ func init() {
 	host := getEnvWithDefault("HOST", "")
 	port := getEnvWithDefault("PORT", "8080")
 
+	// Most common alternative would be X-Forwarded-For
+	ipheader := getEnvWithDefault("FORWARD_IP_HEADER", "CF-Connecting-IP")
+
 	tlsenabled := getEnvWithDefault("TLS", "0")
 	tlsport := getEnvWithDefault("TLSPORT", "8443")
 	tlscert := getEnvWithDefault("TLSCERT", "/opt/ifconfig/.cf/ifconfig.io.crt")
@@ -38,6 +42,7 @@ func init() {
 		hostname: hostname,
 		host:     host,
 		port:     port,
+		ipheader: ipheader,
 		tls:      tlsenabled == "1",
 		tlscert:  tlscert,
 		tlskey:   tlskey,
@@ -71,9 +76,9 @@ func mainHandler(c *gin.Context) {
 		c.Abort()
 	}
 
-	cfIP := net.ParseIP(c.Request.Header.Get("CF-Connecting-IP"))
-	if cfIP != nil {
-		ip.IP = cfIP
+	header_ip := net.ParseIP(c.Request.Header.Get(configuration.ipheader))
+	if header_ip != nil {
+		ip.IP = header_ip
 	}
 
 	if fields[0] == "porttest" {
@@ -192,7 +197,6 @@ func main() {
 		}
 	}(errc)
 
-
 	go func(errc chan error) {
 		errc <- r.Run(fmt.Sprintf("%s:%s", configuration.host, configuration.port))
 	}(errc)