C# Implementation (#2)
C# implementation of SEP-1763 --------- Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Peder Holdgaard Pedersen
GitHub
parent
46d96779d6
commit
45f9e0ef27
1 changed files with 13862 additions and 21 deletions
|
|
@ -0,0 +1,394 @@
|
|||
using ModelContextProtocol.Interceptors;
|
||||
using ModelContextProtocol.Interceptors.Server;
|
||||
using ModelContextProtocol.Protocol;
|
||||
using System.Text.Json;
|
||||
using System.Text.Json.Nodes;
|
||||
using System.Text.RegularExpressions;
|
||||
|
||||
/// <summary>
|
||||
/// Server-side mutation interceptors for MCP operations.
|
||||
/// These interceptors transform requests and responses as they pass through
|
||||
/// the interceptor service, enabling centralized data transformation.
|
||||
/// </summary>
|
||||
[McpServerInterceptorType]
|
||||
public partial class ServerMutationInterceptors
|
||||
{
|
||||
// Patterns for sensitive data redaction
|
||||
private static readonly Regex ApiKeyPattern = new(@"\b(sk_live_|sk_test_|api_key[=:]\s*|apikey[=:]\s*)[a-zA-Z0-9_-]+\b", RegexOptions.Compiled | RegexOptions.IgnoreCase);
|
||||
private static readonly Regex PasswordPattern = new(@"(password|passwd|pwd|secret|token)[=:]\s*[^\s,;]+", RegexOptions.Compiled | RegexOptions.IgnoreCase);
|
||||
private static readonly Regex BearerTokenPattern = new(@"Bearer\s+[a-zA-Z0-9._-]+", RegexOptions.Compiled);
|
||||
private static readonly Regex SsnPattern = new(@"\b\d{3}-\d{2}-\d{4}\b", RegexOptions.Compiled);
|
||||
private static readonly Regex CreditCardPattern = new(@"\b(?:\d{4}[-\s]?){3}\d{4}\b", RegexOptions.Compiled);
|
||||
|
||||
/// <summary>
|
||||
/// Normalizes tool call arguments by trimming whitespace.
|
||||
/// </summary>
|
||||
[McpServerInterceptor(
|
||||
Name = "argument-normalizer",
|
||||
Description = "Normalizes tool call arguments by trimming whitespace",
|
||||
Events = [InterceptorEvents.ToolsCall],
|
||||
Phase = InterceptorPhase.Request,
|
||||
PriorityHint = -100)] // Run early
|
||||
public MutationInterceptorResult NormalizeArguments(JsonNode? payload)
|
||||
{
|
||||
if (payload is null)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
CallToolRequestParams? toolCall;
|
||||
try
|
||||
{
|
||||
toolCall = payload.Deserialize<CallToolRequestParams>();
|
||||
}
|
||||
catch (JsonException)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
if (toolCall?.Arguments is null || toolCall.Arguments.Count == 0)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
var modified = false;
|
||||
var normalizedArgs = new Dictionary<string, object?>();
|
||||
|
||||
foreach (var arg in toolCall.Arguments)
|
||||
{
|
||||
var value = arg.Value;
|
||||
if (value is JsonElement element && element.ValueKind == JsonValueKind.String)
|
||||
{
|
||||
var strValue = element.GetString();
|
||||
var trimmed = strValue?.Trim();
|
||||
if (trimmed != strValue)
|
||||
{
|
||||
normalizedArgs[arg.Key] = trimmed;
|
||||
modified = true;
|
||||
}
|
||||
else
|
||||
{
|
||||
normalizedArgs[arg.Key] = value;
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
normalizedArgs[arg.Key] = value;
|
||||
}
|
||||
}
|
||||
|
||||
if (modified)
|
||||
{
|
||||
var mutatedPayload = new JsonObject
|
||||
{
|
||||
["name"] = toolCall.Name,
|
||||
["arguments"] = JsonSerializer.SerializeToNode(normalizedArgs)
|
||||
};
|
||||
|
||||
var result = MutationInterceptorResult.Mutated(mutatedPayload);
|
||||
result.Info = new JsonObject { ["action"] = "trimmed whitespace from string arguments" };
|
||||
return result;
|
||||
}
|
||||
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Redacts sensitive information from tool responses.
|
||||
/// </summary>
|
||||
[McpServerInterceptor(
|
||||
Name = "response-redactor",
|
||||
Description = "Redacts sensitive information from tool responses",
|
||||
Events = [InterceptorEvents.ToolsCall],
|
||||
Phase = InterceptorPhase.Response,
|
||||
PriorityHint = 100)] // Run late
|
||||
public MutationInterceptorResult RedactResponse(JsonNode? payload)
|
||||
{
|
||||
if (payload is null)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
CallToolResult? result;
|
||||
try
|
||||
{
|
||||
result = payload.Deserialize<CallToolResult>();
|
||||
}
|
||||
catch (JsonException)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
if (result?.Content is null || result.Content.Count == 0)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
var modified = false;
|
||||
var redactions = new List<string>();
|
||||
var newContent = new List<ContentBlock>();
|
||||
|
||||
foreach (var content in result.Content)
|
||||
{
|
||||
if (content is TextContentBlock textBlock)
|
||||
{
|
||||
var text = textBlock.Text ?? string.Empty;
|
||||
var originalText = text;
|
||||
|
||||
// Redact API keys
|
||||
if (ApiKeyPattern.IsMatch(text))
|
||||
{
|
||||
text = ApiKeyPattern.Replace(text, "[REDACTED_API_KEY]");
|
||||
redactions.Add("api_key");
|
||||
}
|
||||
|
||||
// Redact passwords/secrets
|
||||
if (PasswordPattern.IsMatch(text))
|
||||
{
|
||||
text = PasswordPattern.Replace(text, "[REDACTED_SECRET]");
|
||||
redactions.Add("password");
|
||||
}
|
||||
|
||||
// Redact bearer tokens
|
||||
if (BearerTokenPattern.IsMatch(text))
|
||||
{
|
||||
text = BearerTokenPattern.Replace(text, "Bearer [REDACTED_TOKEN]");
|
||||
redactions.Add("bearer_token");
|
||||
}
|
||||
|
||||
// Redact SSNs
|
||||
if (SsnPattern.IsMatch(text))
|
||||
{
|
||||
text = SsnPattern.Replace(text, "XXX-XX-XXXX");
|
||||
redactions.Add("ssn");
|
||||
}
|
||||
|
||||
// Redact credit cards
|
||||
if (CreditCardPattern.IsMatch(text))
|
||||
{
|
||||
text = CreditCardPattern.Replace(text, "XXXX-XXXX-XXXX-XXXX");
|
||||
redactions.Add("credit_card");
|
||||
}
|
||||
|
||||
if (text != originalText)
|
||||
{
|
||||
modified = true;
|
||||
newContent.Add(new TextContentBlock { Text = text });
|
||||
}
|
||||
else
|
||||
{
|
||||
newContent.Add(content);
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
newContent.Add(content);
|
||||
}
|
||||
}
|
||||
|
||||
if (modified)
|
||||
{
|
||||
var mutatedResult = new CallToolResult
|
||||
{
|
||||
Content = newContent,
|
||||
IsError = result.IsError
|
||||
};
|
||||
|
||||
var mutatedPayload = JsonSerializer.SerializeToNode(mutatedResult);
|
||||
var mutationResult = MutationInterceptorResult.Mutated(mutatedPayload);
|
||||
mutationResult.Info = new JsonObject
|
||||
{
|
||||
["action"] = "redacted sensitive data",
|
||||
["types"] = JsonNode.Parse($"[\"{string.Join("\", \"", redactions.Distinct())}\"]")
|
||||
};
|
||||
return mutationResult;
|
||||
}
|
||||
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Adds tracking metadata to tool requests.
|
||||
/// </summary>
|
||||
[McpServerInterceptor(
|
||||
Name = "request-metadata-injector",
|
||||
Description = "Adds tracking metadata to tool requests",
|
||||
Events = [InterceptorEvents.ToolsCall],
|
||||
Phase = InterceptorPhase.Request,
|
||||
PriorityHint = 100)] // Run late
|
||||
public MutationInterceptorResult InjectRequestMetadata(JsonNode? payload)
|
||||
{
|
||||
if (payload is not JsonObject obj)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
// Clone the payload and add metadata
|
||||
var mutatedPayload = obj.DeepClone() as JsonObject ?? new JsonObject();
|
||||
|
||||
// Add or update _meta object
|
||||
if (mutatedPayload["_meta"] is not JsonObject meta)
|
||||
{
|
||||
meta = new JsonObject();
|
||||
mutatedPayload["_meta"] = meta;
|
||||
}
|
||||
|
||||
meta["interceptor_processed"] = true;
|
||||
meta["interceptor_timestamp"] = DateTimeOffset.UtcNow.ToString("O");
|
||||
meta["interceptor_id"] = Guid.NewGuid().ToString("N")[..8];
|
||||
|
||||
var result = MutationInterceptorResult.Mutated(mutatedPayload);
|
||||
result.Info = new JsonObject { ["action"] = "added tracking metadata" };
|
||||
return result;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Sanitizes resource content by removing potentially dangerous HTML/script tags.
|
||||
/// </summary>
|
||||
[McpServerInterceptor(
|
||||
Name = "content-sanitizer",
|
||||
Description = "Sanitizes resource content by removing dangerous tags",
|
||||
Events = [InterceptorEvents.ResourcesRead],
|
||||
Phase = InterceptorPhase.Response,
|
||||
PriorityHint = 50)]
|
||||
public MutationInterceptorResult SanitizeContent(JsonNode? payload)
|
||||
{
|
||||
if (payload is null)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
ReadResourceResult? result;
|
||||
try
|
||||
{
|
||||
result = payload.Deserialize<ReadResourceResult>();
|
||||
}
|
||||
catch (JsonException)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
if (result?.Contents is null || result.Contents.Count == 0)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
var modified = false;
|
||||
var sanitizations = new List<string>();
|
||||
var newContents = new List<ResourceContents>();
|
||||
|
||||
foreach (var content in result.Contents)
|
||||
{
|
||||
if (content is TextResourceContents textContent)
|
||||
{
|
||||
var text = textContent.Text ?? string.Empty;
|
||||
var originalText = text;
|
||||
|
||||
// Remove script tags
|
||||
var scriptPattern = new Regex(@"<script[^>]*>[\s\S]*?</script>", RegexOptions.IgnoreCase);
|
||||
if (scriptPattern.IsMatch(text))
|
||||
{
|
||||
text = scriptPattern.Replace(text, "[REMOVED_SCRIPT]");
|
||||
sanitizations.Add("script_tags");
|
||||
}
|
||||
|
||||
// Remove onclick/onerror handlers
|
||||
var eventHandlerPattern = new Regex(@"\s+on\w+\s*=\s*[""'][^""']*[""']", RegexOptions.IgnoreCase);
|
||||
if (eventHandlerPattern.IsMatch(text))
|
||||
{
|
||||
text = eventHandlerPattern.Replace(text, "");
|
||||
sanitizations.Add("event_handlers");
|
||||
}
|
||||
|
||||
// Remove javascript: URLs
|
||||
var jsUrlPattern = new Regex(@"javascript\s*:", RegexOptions.IgnoreCase);
|
||||
if (jsUrlPattern.IsMatch(text))
|
||||
{
|
||||
text = jsUrlPattern.Replace(text, "[REMOVED_JS_URL]");
|
||||
sanitizations.Add("javascript_urls");
|
||||
}
|
||||
|
||||
if (text != originalText)
|
||||
{
|
||||
modified = true;
|
||||
newContents.Add(new TextResourceContents
|
||||
{
|
||||
Uri = textContent.Uri,
|
||||
MimeType = textContent.MimeType,
|
||||
Text = text
|
||||
});
|
||||
}
|
||||
else
|
||||
{
|
||||
newContents.Add(content);
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
newContents.Add(content);
|
||||
}
|
||||
}
|
||||
|
||||
if (modified)
|
||||
{
|
||||
var mutatedResult = new ReadResourceResult
|
||||
{
|
||||
Contents = newContents
|
||||
};
|
||||
|
||||
var mutatedPayload = JsonSerializer.SerializeToNode(mutatedResult);
|
||||
var mutationResult = MutationInterceptorResult.Mutated(mutatedPayload);
|
||||
mutationResult.Info = new JsonObject
|
||||
{
|
||||
["action"] = "sanitized content",
|
||||
["removed"] = JsonNode.Parse($"[\"{string.Join("\", \"", sanitizations.Distinct())}\"]")
|
||||
};
|
||||
return mutationResult;
|
||||
}
|
||||
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Transforms tool names to enforce naming conventions.
|
||||
/// </summary>
|
||||
[McpServerInterceptor(
|
||||
Name = "tool-name-normalizer",
|
||||
Description = "Normalizes tool names to enforce naming conventions",
|
||||
Events = [InterceptorEvents.ToolsCall],
|
||||
Phase = InterceptorPhase.Request,
|
||||
PriorityHint = -50)]
|
||||
public MutationInterceptorResult NormalizeToolName(JsonNode? payload)
|
||||
{
|
||||
if (payload is not JsonObject obj)
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
var name = obj["name"]?.GetValue<string>();
|
||||
if (string.IsNullOrEmpty(name))
|
||||
{
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
|
||||
// Normalize: lowercase, replace spaces with underscores
|
||||
var normalizedName = name.ToLowerInvariant().Replace(" ", "_").Replace("-", "_");
|
||||
|
||||
if (normalizedName != name)
|
||||
{
|
||||
var mutatedPayload = obj.DeepClone() as JsonObject ?? new JsonObject();
|
||||
mutatedPayload["name"] = normalizedName;
|
||||
|
||||
var result = MutationInterceptorResult.Mutated(mutatedPayload);
|
||||
result.Info = new JsonObject
|
||||
{
|
||||
["action"] = "normalized tool name",
|
||||
["original"] = name,
|
||||
["normalized"] = normalizedName
|
||||
};
|
||||
return result;
|
||||
}
|
||||
|
||||
return MutationInterceptorResult.Unchanged(payload);
|
||||
}
|
||||
}
|
||||
Loading…
Reference in a new issue