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Validate UTF-8 in WebSocket text frames (RFC 6455 §8.1, close 1007) #40

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Merged
hellerve merged 1 commit into from
Jul 10, 2026
Merged

Validate UTF-8 in WebSocket text frames (RFC 6455 §8.1, close 1007) #40

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8 changes: 8 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,5 +1,13 @@
# Changelog

## Unreleased

### Fixed
- **WebSocket text frames with invalid UTF-8 now close with 1007.** Per
RFC 6455 §8.1, incoming text payloads (and reassembled fragmented text
messages) are validated as UTF-8; malformed data fails the connection
with close code 1007 instead of being passed to the handler.

## 0.7.0 (2026-07-06)

### Added
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37 changes: 26 additions & 11 deletions web.carp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
(load "git@github.com:carpentry-org/json@0.2.2")
(load "git@github.com:carpentry-org/file@0.1.2")
(load "git@github.com:carpentry-org/log@0.1.1")
(load "git@github.com:carpentry-org/utf8.carp@0.1.0")

(defmodule SHA1
(hidden mask32)
Expand Down Expand Up @@ -1773,12 +1774,20 @@ fallback.")
&fd)
(Map.remove! (ConnState.ws-frag-start cs)
&fd)
; fragments are reassembled before dispatch, so this
; UTF-8 check is message-level (RFC 6455 §8.1 Non-Strict)
(if (= orig-op 1)
(~(WSRoute.handler (Array.unsafe-nth ws-routes
route-idx))
&(WSEvent.Message (String.from-bytes &frag-buf))
&params
&ws)
(if (UTF8.valid? &frag-buf)
(~(WSRoute.handler (Array.unsafe-nth ws-routes
route-idx))
&(WSEvent.Message (String.from-bytes &frag-buf))
&params
&ws)
(do
(Array.push-back! (WebSocket.outbox &ws)
(WebSocket.encode-close-with-code 1007))
(set! should-close true)
(break)))
(~(WSRoute.handler (Array.unsafe-nth ws-routes
route-idx)) &(WSEvent.Binary @&frag-buf)
&params
Expand All @@ -1804,12 +1813,18 @@ fallback.")
(break))
(do
(if (= op 1)
(~(WSRoute.handler (Array.unsafe-nth ws-routes
route-idx))
&(WSEvent.Message
(String.from-bytes (WSFrame.payload &frame)))
&params
&ws)
(if (UTF8.valid? (WSFrame.payload &frame))
(~(WSRoute.handler (Array.unsafe-nth ws-routes
route-idx))
&(WSEvent.Message
(String.from-bytes (WSFrame.payload &frame)))
&params
&ws)
(do
(Array.push-back! (WebSocket.outbox &ws)
(WebSocket.encode-close-with-code 1007))
(set! should-close true)
(break)))
(~(WSRoute.handler (Array.unsafe-nth ws-routes
route-idx))
&(WSEvent.Binary @(WSFrame.payload &frame))
Expand Down
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