Adding support for ServerIP context

caddyhttp/httpserver/context.go

@@ -84,6 +84,29 @@ func (c Context) IP() string {
 	return ip
 }
 
+// To mock the net.InterfaceAddrs from the test.
+var networkInterfacesFn = net.InterfaceAddrs
+
+// ServerIP gets the (local) IP address of the server.
+// TODO: The bind directive should be honored in this method (see PR #1474).
+func (c Context) ServerIP() string {
+	addrs, err := networkInterfacesFn()
+	if err != nil {
+		return ""
+	}
+
+	for _, address := range addrs {
+		// Validate the address and check if it's not a loopback
+		if ipnet, ok := address.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
+			if ipnet.IP.To4() != nil || ipnet.IP.To16() != nil {
+				return ipnet.IP.String()
+			}
+		}
+	}
+
+	return ""
+}
+
 // URI returns the raw, unprocessed request URI (including query
 // string and hash) obtained directly from the Request-Line of
 // the HTTP request.