Refactor ForwardedHeaders configuration to improve proxy and network handling

Updated the ForwardedHeadersOptions configuration in Program.cs to utilize a new ReadList method for better handling of known proxies and networks. This change allows for flexible input from environment variables and appsettings, ensuring proper parsing of both comma-separated values and array formats. Enhanced code readability and maintainability by consolidating the logic for reading configuration values.

backend/src/TeleWave.Api/Program.cs

@@ -38,26 +38,35 @@ builder.Services.Configure<ForwardedHeadersOptions>(options =>
 {
     options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
 
-    foreach (
-        var proxy in builder
-            .Configuration.GetSection("ForwardedHeaders:KnownProxies")
-            .Get<string[]>()
-            ?? []
-    )
+    foreach (var proxy in ReadList(builder.Configuration, "ForwardedHeaders:KnownProxies"))
         options.KnownProxies.Add(IPAddress.Parse(proxy));
 
-    foreach (
-        var network in builder
-            .Configuration.GetSection("ForwardedHeaders:KnownNetworks")
-            .Get<string[]>()
-            ?? []
-    )
+    foreach (var network in ReadList(builder.Configuration, "ForwardedHeaders:KnownNetworks"))
     {
         var parts = network.Split('/');
         options.KnownIPNetworks.Add(
             new System.Net.IPNetwork(IPAddress.Parse(parts[0]), int.Parse(parts[1]))
         );
     }
+
+    // Список доверенных прокси/сетей приходит из .env одной строкой (env-переменная по одному ключу
+    // в string[] не биндится) — принимаем и запятые, и массив appsettings/индексы __0. Иначе
+    // задокументированная в .env.example запись через запятую молча игнорировалась бы, оставляя
+    // доверие только loopback и обрывая подхват X-Forwarded-Proto.
+    static string[] ReadList(IConfiguration config, string key)
+    {
+        var array = config.GetSection(key).Get<string[]>();
+        if (array is { Length: > 0 })
+            return array;
+
+        var scalar = config[key];
+        return string.IsNullOrWhiteSpace(scalar)
+            ? []
+            : scalar.Split(
+                ',',
+                StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries
+            );
+    }
 });
 
 builder.Services.AddHttpContextAccessor();