HttpClientTransportOAuthTokenHelper to extract and inject the OAuth token, until we get the TokenCache (modelcontextprotocol/csharp-sdk#834).

Author: halllo

MyMCPClient.Console/HttpClientTransportOAuthTokenHelper.cs

@@ -0,0 +1,45 @@
+using ModelContextProtocol.Client;
+using System.Reflection;
+using System.Text.Json;
+
+/// <summary>
+/// Extract and inject the OAuth token, until we get the TokenCache (https://github.com/modelcontextprotocol/csharp-sdk/pull/834).
+/// </summary>
+public static class HttpClientTransportOAuthTokenHelper
+{
+	public static string? ExtractOAuthToken(this HttpClientTransport httpTransport)
+	{
+		var mcpHttpClientField = httpTransport.GetType().GetField("_mcpHttpClient", BindingFlags.NonPublic | BindingFlags.Instance);
+		var mcpHttpClient = mcpHttpClientField?.GetValue(httpTransport);
+		var clientOAuthProviderField = (mcpHttpClient?.GetType() as TypeInfo)?.DeclaredFields.FirstOrDefault(df => df.FieldType.FullName == "ModelContextProtocol.Authentication.ClientOAuthProvider");
+		var clientOAuthProvider = clientOAuthProviderField?.GetValue(mcpHttpClient);
+		var tokenField = clientOAuthProvider?.GetType().GetField("_token", BindingFlags.NonPublic | BindingFlags.Instance);
+		var token = tokenField?.GetValue(clientOAuthProvider);
+		var obtainedAtProperty = token?.GetType().GetProperty("ObtainedAt");
+		var obtainedAt = obtainedAtProperty?.GetValue(token);
+		if (token == null || obtainedAt == null) return null;
+		var tokenJson = JsonSerializer.Serialize(token, token!.GetType());
+		return JsonSerializer.Serialize(new { tokenJson, obtainedAt });
+	}
+
+	public static void InjectOAuthToken(this HttpClientTransport httpTransport, string? token)
+	{
+		if (string.IsNullOrEmpty(token)) return;
+		var tokenObj = JsonSerializer.Deserialize<JsonElement>(token);
+		var tokenJson = tokenObj.GetProperty("tokenJson").GetString();
+		var obtainedAt = tokenObj.GetProperty("obtainedAt").GetDateTimeOffset();
+		var mcpHttpClientField = httpTransport.GetType().GetField("_mcpHttpClient", BindingFlags.NonPublic | BindingFlags.Instance);
+		var mcpHttpClient = mcpHttpClientField?.GetValue(httpTransport);
+		var clientOAuthProviderField = (mcpHttpClient?.GetType() as TypeInfo)?.DeclaredFields.FirstOrDefault(df => df.FieldType.FullName == "ModelContextProtocol.Authentication.ClientOAuthProvider");
+		var clientOAuthProvider = clientOAuthProviderField?.GetValue(mcpHttpClient);
+		var tokenField = clientOAuthProvider?.GetType().GetField("_token", BindingFlags.NonPublic | BindingFlags.Instance);
+		var tokenType = tokenField?.FieldType;
+		var deserializedToken = JsonSerializer.Deserialize(tokenJson!, tokenType!);
+		if (deserializedToken != null)
+		{
+			var obtainedAtProperty = tokenType!.GetProperty("ObtainedAt");
+			obtainedAtProperty?.SetValue(deserializedToken, obtainedAt);
+			tokenField?.SetValue(clientOAuthProvider, deserializedToken);
+		}
+	}
+}

MyMCPClient.Console/Program.cs

@@ -1,13 +1,10 @@
 using Microsoft.Extensions.AI;
-using Microsoft.Extensions.Logging;
 using ModelContextProtocol.Client;
-using System.ClientModel;
 using System.Diagnostics;
 using System.Net;
 using System.Text;
-using System.Web;
-using System.Linq;
 using System.Text.Json;
+using System.Web;
 
 
 // Local tool
@@ -23,7 +20,7 @@
 //var tokenResponse = await http.GetAsync($"https://localhost:7296/debug_token?userId={Guid.NewGuid()}&userName={"bob"}");
 //var debugtoken = await tokenResponse.Content.ReadFromJsonAsync<string>();
 //http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", debugtoken);
-await using var mcpClient2 = await McpClient.CreateAsync(new HttpClientTransport(new()
+var httpClientTransport = new HttpClientTransport(new()
 {
 	Name = "Vibe MCP Server",
 	Endpoint = new Uri("http://localhost:5253/bot"),
@@ -37,7 +34,12 @@
 		Scopes = ["openid", "profile", "verification", "notes", "admin", "offline_access"],//the client we registered supports refresh tokens
 		TokenCache = new TokenCacheFile("token_cache.json"),
 	},
-}, http));
+}, http);
+
+//var token = File.Exists("token.json") ? File.ReadAllText("token.json") : null;
+//httpClientTransport.InjectOAuthToken(token);
+await using var mcpClient2 = await McpClient.CreateAsync(httpClientTransport);
+//File.WriteAllText("token.json", httpClientTransport.ExtractOAuthToken());
 
 /// Taken from https://github.com/modelcontextprotocol/csharp-sdk/blob/c0440760ac363d817cbdca87e1ab7eff7e74a025/samples/ProtectedMCPClient/Program.cs#L72
 static async Task<string?> HandleAuthorizationUrlAsync(Uri authorizationUrl, Uri redirectUri, CancellationToken cancellationToken)