Allow trusted proxy via APP_TRUSTED_PROXIES (#9196)

* Allow trusted proxy via APP_TRUSTED_PROXIES
Set to '*' by default to emulate legacy behavior.
Set up doc describing environment variables

* Create helper to parse environment variables into arrays properly.

* Update doc blocks

config/trustedproxy.php

@@ -0,0 +1,51 @@
+<?php
+
+return [
+
+    /*
+     * Set trusted proxy IP addresses.
+     *
+     * Both IPv4 and IPv6 addresses are
+     * supported, along with CIDR notation.
+     *
+     * The "*" character is syntactic sugar
+     * within TrustedProxy to trust any proxy
+     * that connects directly to your server,
+     * a requirement when you cannot know the address
+     * of your proxy (e.g. if using ELB or similar).
+     *
+     */
+    'proxies' => \LibreNMS\Util\Env::parseArray('APP_TRUSTED_PROXIES', '*', ['', '*', '**']),
+
+    /*
+     * To trust one or more specific proxies that connect
+     * directly to your server, use an array of IP addresses:
+     */
+     # 'proxies' => ['192.168.1.1'],
+
+    /*
+     * Or, to trust all proxies that connect
+     * directly to your server, use a "*"
+     */
+     # 'proxies' => '*',
+
+    /*
+     * Which headers to use to detect proxy related data (For, Host, Proto, Port)
+     * 
+     * Options include:
+     * 
+     * - Illuminate\Http\Request::HEADER_X_FORWARDED_ALL (use all x-forwarded-* headers to establish trust)
+     * - Illuminate\Http\Request::HEADER_FORWARDED (use the FORWARDED header to establish trust)
+     * 
+     * @link https://symfony.com/doc/current/deployment/proxies.html
+     */
+    'headers' => Illuminate\Http\Request::HEADER_X_FORWARDED_ALL,
+//    'headers' => [
+//        (defined('Illuminate\Http\Request::HEADER_FORWARDED') ? Illuminate\Http\Request::HEADER_FORWARDED : 'forwarded') => 'FORWARDED',
+//        \Illuminate\Http\Request::HEADER_CLIENT_IP    => 'X_FORWARDED_FOR',
+//        \Illuminate\Http\Request::HEADER_CLIENT_HOST  => 'X_FORWARDED_HOST',
+//        \Illuminate\Http\Request::HEADER_CLIENT_PROTO => 'X_FORWARDED_PROTO',
+//        \Illuminate\Http\Request::HEADER_CLIENT_PORT  => 'X_FORWARDED_PORT',
+//    ]
+    
+];