fix: bound MCP input before line parsing#3
Merged
Conversation
There was a problem hiding this comment.
Pull request overview
This PR hardens the MCP stdio transport by replacing readline-based line accumulation with a bounded byte parser so oversized input can be rejected as soon as it exceeds maxLineBytes, before a newline is received/buffered.
Changes:
- Replaces Node
readlineline handling with a custom incremental byte parser that enforcesmaxLineBytesduring streaming reads. - Adds a regression test ensuring oversized input is rejected even when no newline has yet been buffered.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
src/mcp.ts |
Implements bounded streaming line parsing and input listener cleanup to enforce maxLineBytes before newline completion. |
tests/mcp.test.ts |
Adds test coverage for rejecting oversized input prior to newline buffering. |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
Comment on lines
+144
to
+151
| const newline = bytes.indexOf(0x0a, offset); | ||
| const end = newline < 0 ? bytes.byteLength : newline; | ||
| const segmentBytes = end - offset; | ||
| if (!discardingOversizedLine) { | ||
| if (lineBytes + segmentBytes > maxLineBytes) { | ||
| discardingOversizedLine = true; | ||
| lineBytes = 0; | ||
| rejectOversizedLine(); |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Closes #2. Replaces unbounded readline accumulation with a byte-capped parser and proves oversized chunked input is rejected before newline buffering.