Perf optimization for Bilibili provider

src/AspNet.Security.OAuth.Bilibili/BilibiliAuthenticationHandler.cs

@@ -90,17 +90,19 @@ private static string ComputeHmacSHA256(string key, string data)
         return Convert.ToHexStringLower(hash);
     }
 
-    private static string BuildSignatureString(HttpRequestMessage request, string appSecret)
+    private static string BuildSignatureString(SortedList<string, string> xbiliHeaders, string appSecret)
     {
-        var headers = request.Headers
-            .Where(h => h.Key.StartsWith("x-bili-", StringComparison.OrdinalIgnoreCase))
-            .OrderBy(h => h.Key)
-            .Select(h => $"{h.Key}:{string.Join(",", h.Value)}")
-            .ToList();
-
-        var signature = string.Join('\n', headers);
+        var sb = new StringBuilder(256); // 256 is an estimated size for the plain text
+        foreach ((var name, var value) in xbiliHeaders)
+        {
+            sb.Append(name)
+              .Append(':')
+              .Append(value)
+              .Append('\n');
+        }
 
-        return ComputeHmacSHA256(appSecret, signature);
+        var signSrcText = sb.ToString(0, sb.Length - 1); // Ignore the last '\n'
+        return ComputeHmacSHA256(appSecret, signSrcText);
     }
 
     protected override async Task<AuthenticationTicket> CreateTicketAsync(
@@ -110,14 +112,14 @@ protected override async Task<AuthenticationTicket> CreateTicketAsync(
     {
         using var request = new HttpRequestMessage(HttpMethod.Get, Options.UserInformationEndpoint);
         request.Headers.Add("access-token", tokens.AccessToken);
-        request.Headers.Add("x-bili-accesskeyid", Options.ClientId);
-        request.Headers.Add("x-bili-content-md5", "d41d8cd98f00b204e9800998ecf8427e"); // It's a GET request so there's no content, so we send the MD5 hash of an empty string
-        request.Headers.Add("x-bili-signature-method", "HMAC-SHA256");
-        request.Headers.Add("x-bili-signature-nonce", Base64Url.EncodeToString(RandomNumberGenerator.GetBytes(256 / 8)));
-        request.Headers.Add("x-bili-signature-version", "2.0");
-        request.Headers.Add("x-bili-timestamp", TimeProvider.GetUtcNow().ToUnixTimeSeconds().ToString(CultureInfo.InvariantCulture));
-
-        var signature = BuildSignatureString(request, Options.ClientSecret);
+
+        var xbiliHeaders = BuildXBiliHeaders();
+        foreach ((var name, var value) in xbiliHeaders)
+        {
+            request.Headers.Add(name, value);
+        }
+
+        var signature = BuildSignatureString(xbiliHeaders, Options.ClientSecret);
         request.Headers.Add("Authorization", signature);
 
         request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
@@ -145,6 +147,23 @@ protected override async Task<AuthenticationTicket> CreateTicketAsync(
         return new AuthenticationTicket(context.Principal!, context.Properties, Scheme.Name);
     }
 
+    private SortedList<string, string> BuildXBiliHeaders() => new(6, StringComparer.OrdinalIgnoreCase)
+    {
+        { "x-bili-accesskeyid", Options.ClientId },
+        { "x-bili-content-md5", "d41d8cd98f00b204e9800998ecf8427e" }, // It's a GET request so there's no content, so we send the MD5 hash of an empty string
+        { "x-bili-signature-method", "HMAC-SHA256" },
+        { "x-bili-signature-nonce", GenerateNonce() },
+        { "x-bili-signature-version", "2.0" },
+        { "x-bili-timestamp", TimeProvider.GetUtcNow().ToUnixTimeSeconds().ToString(CultureInfo.InvariantCulture) }
+    };
+
+    private static string GenerateNonce()
+    {
+        Span<byte> bytes = stackalloc byte[256 / 8];
+        RandomNumberGenerator.Fill(bytes);
+        return Base64Url.EncodeToString(bytes);
+    }
+
     /// <summary>
     /// Check the code sent back by server for potential server errors.
     /// </summary>
@@ -154,14 +173,13 @@ protected override async Task<AuthenticationTicket> CreateTicketAsync(
     /// <returns>True if succeed, otherwise false.</returns>
     private static bool ValidateReturnCode(JsonElement element, out int code)
     {
-        code = 0;
         if (!element.TryGetProperty("code", out JsonElement errorCodeElement))
         {
+            code = 0;
             return true;
         }
 
         code = errorCodeElement.GetInt32();
-
         return code == 0;
     }
 

test/AspNet.Security.OAuth.Providers.Tests/Bilibili/BilibiliTests.cs

@@ -4,7 +4,6 @@
  * for more information concerning the license and the contributors participating to this project.
  */
 
-using System.Web;
 using Microsoft.AspNetCore.WebUtilities;
 
 namespace AspNet.Security.OAuth.Bilibili;