d01a626b76Re-implementation of C# interceptors SDK with clearer focus on server-side / gateway interceptors. Fixes a lot of issues with the existing implementation. Still more boilerplate than I'm happy with, but this is better than what was there. Will refine further in later PRs.
73 lines
2.9 KiB
C#
73 lines
2.9 KiB
C#
using System.Runtime.CompilerServices;
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using ModelContextProtocol.Client;
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using ModelContextProtocol.Interceptors.Gateway;
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using ModelContextProtocol.Interceptors.Protocol;
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using ModelContextProtocol.Server;
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// ──────────────────────────────────────────────────────────────────────
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// Transparent Proxy Sample
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//
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// Creates a transparent MCP proxy that:
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// 1. Connects as a CLIENT to a backend MCP server (everything server)
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// 2. Connects as a CLIENT to an interceptor server (PII + email interceptors)
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// 3. Exposes itself as a SERVER via stdio
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//
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// To connecting clients (e.g. Claude Desktop), this proxy appears to be
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// the everything server — but all requests flow through the interceptor
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// chain first (validation, mutation, sink).
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//
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// Claude Desktop config example:
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// {
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// "mcpServers": {
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// "everything-with-interceptors": {
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// "command": "dotnet",
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// "args": ["run", "--project", "path/to/TransparentProxySample"]
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// }
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// }
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// }
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// ──────────────────────────────────────────────────────────────────────
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// 1. Connect to the interceptor server
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var interceptorServerPath = Path.Combine(GetSourceDir(), "..", "InterceptorServerSample");
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await using var interceptorClient = await McpClient.CreateAsync(
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new StdioClientTransport(new()
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{
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Name = "InterceptorServer",
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Command = "dotnet",
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Arguments = ["run", "--project", interceptorServerPath],
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}));
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// 2. Connect to the backend everything server
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await using var backendClient = await McpClient.CreateAsync(
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new StdioClientTransport(new()
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{
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Name = "EverythingServer",
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Command = "npx",
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Arguments = ["-y", "@modelcontextprotocol/server-everything"],
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}));
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// 3. Create the gateway
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await using var gateway = new McpInterceptorGateway(new McpInterceptorGatewayOptions
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{
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BackendClient = backendClient,
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InterceptorClients = [interceptorClient],
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Events = [InterceptionEvents.ToolsCall], // Only intercept tools/call
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});
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// 4. Configure server options and create the proxy server on stdio
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var serverOptions = new McpServerOptions
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{
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ServerInfo = new() { Name = "interceptor-proxy", Version = "1.0.0" },
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};
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gateway.ConfigureServerOptions(serverOptions);
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await using var server = McpServer.Create(new StdioServerTransport("interceptor-proxy"), serverOptions);
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// 5. Forward backend notifications to connected clients
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gateway.RegisterNotificationForwarding(server);
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// 6. Run the proxy — it will serve requests until the client disconnects
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await server.RunAsync();
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static string GetSourceDir([CallerFilePath] string? path = null) =>
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Path.GetDirectoryName(path) ?? throw new InvalidOperationException();
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