Add custom HTTP headers for subscription updates (#10118)

* Add custom HTTP headers for subscription updates

* Res

---------

Co-authored-by: 2dust <31833384+2dust@users.noreply.github.com>

v2rayN/ServiceLib/Helper/DownloaderHelper.cs

@@ -8,7 +8,8 @@ public class DownloaderHelper
     private static readonly Lazy<DownloaderHelper> _instance = new(() => new());
     public static DownloaderHelper Instance => _instance.Value;
 
-    public async Task<string?> DownloadStringAsync(IWebProxy? webProxy, string url, string? userAgent, int timeout)
+    public async Task<string?> DownloadStringAsync(IWebProxy? webProxy, string url, string? userAgent, int timeout,
+        IReadOnlyDictionary<string, string>? requestHeaders = null, string? acceptHeader = null)
     {
         if (url.IsNullOrEmpty())
         {
@@ -28,6 +29,7 @@ public class DownloaderHelper
         var requestConfiguration = new RequestConfiguration()
         {
             Headers = headers,
+            Accept = acceptHeader,
             UserAgent = userAgent,
             ConnectTimeout = connectTimeout * 1000,
             Proxy = webProxy
@@ -37,7 +39,7 @@ public class DownloaderHelper
             BlockTimeout = timeout * 1000,
             MaxTryAgainOnFailure = 2,
             RequestConfiguration = requestConfiguration,
-            CustomHttpMessageHandlerFactory = () => GetSocketsHttpHandler(requestConfiguration),
+            CustomHttpMessageHandlerFactory = () => HttpRequestHeadersHelper.CreateHandler(GetSocketsHttpHandler(requestConfiguration), requestHeaders),
         };
 
         await using var downloader = new Downloader.DownloadService(downloadOpt);

v2rayN/ServiceLib/Helper/HttpRequestHeadersHelper.cs

@@ -0,0 +1,88 @@
+namespace ServiceLib.Helper;
+
+public static class HttpRequestHeadersHelper
+{
+    public static bool TryParse(string? json, out Dictionary<string, string> headers)
+    {
+        headers = new(StringComparer.OrdinalIgnoreCase);
+        if (string.IsNullOrWhiteSpace(json))
+        {
+            return true;
+        }
+
+        try
+        {
+            using var document = JsonDocument.Parse(json);
+            if (document.RootElement.ValueKind != JsonValueKind.Object)
+            {
+                return false;
+            }
+
+            var parsed = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            using var request = new HttpRequestMessage { Content = new ByteArrayContent([]) };
+            foreach (var property in document.RootElement.EnumerateObject())
+            {
+                if (property.Value.ValueKind != JsonValueKind.String
+                    || !parsed.TryAdd(property.Name, property.Value.GetString()!)
+                    || !TryAddHeader(request, property.Name, parsed[property.Name]))
+                {
+                    return false;
+                }
+            }
+
+            headers = parsed;
+            return true;
+        }
+        catch (Exception ex) when (ex is JsonException or ArgumentException or FormatException)
+        {
+            return false;
+        }
+    }
+
+    public static HttpMessageHandler CreateHandler(HttpMessageHandler innerHandler, IReadOnlyDictionary<string, string>? headers)
+    {
+        return headers is { Count: > 0 } ? new RequestHeadersHandler(innerHandler, headers) : innerHandler;
+    }
+
+    private static bool TryAddHeader(HttpRequestMessage request, string name, string value)
+    {
+        if (value.Any(c => char.IsControl(c) && c != '\t'))
+        {
+            return false;
+        }
+
+        return request.Headers.TryAddWithoutValidation(name, value)
+            || request.Content!.Headers.TryAddWithoutValidation(name, value);
+    }
+
+    private sealed class RequestHeadersHandler(HttpMessageHandler innerHandler, IReadOnlyDictionary<string, string> headers)
+        : DelegatingHandler(innerHandler)
+    {
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            using var customHeaders = new HttpRequestMessage { Content = new ByteArrayContent([]) };
+            foreach (var header in headers)
+            {
+                if (!TryAddHeader(customHeaders, header.Key, header.Value))
+                {
+                    throw new FormatException(ResUI.SubRequestHeadersInvalid);
+                }
+            }
+
+            // Apply after each downloader's defaults, replacing headers without changing their values.
+            foreach (var header in customHeaders.Headers.NonValidated)
+            {
+                request.Headers.Remove(header.Key);
+                request.Headers.TryAddWithoutValidation(header.Key, header.Value);
+            }
+            foreach (var header in customHeaders.Content.Headers.NonValidated)
+            {
+                request.Content ??= new ByteArrayContent([]);
+                request.Content.Headers.Remove(header.Key);
+                request.Content.Headers.TryAddWithoutValidation(header.Key, header.Value);
+            }
+
+            return base.SendAsync(request, cancellationToken);
+        }
+    }
+}