|
The cid: namespacing scheme (cid:<prefix>!<id>) is only unambiguous
because the prefix half is guaranteed free of '!': the first '!' in the
result is always the separator, so an attacker-controlled Content-ID
containing '!' only extends the id half rather than colliding with a
different prefix. That invariant previously existed only as a comment.
Add Q_ASSERT_X at both independent call sites that perform this
concatenation (CidSchemeHandler::namespacedKey and
HtmlBuilder::namespaceCids) so a future prefix generator that violates it
traps in debug builds, per Task 5's precedent of not letting one unit's
correctness depend silently on another's future behaviour. Since
Q_ASSERT compiles out in release, pin the property that actually matters
release builds too test: distinct (prefix, id) pairs across a documented
"m<index>" prefix set and hostile Content-IDs (containing '!', percent-
encoded '!', empty, leading/trailing '!') never collide, and the key
always splits at its first '!' back to the exact original prefix.
|
|
HtmlBuilder renders parsed messages (and whole threads, as one document,
so newsletter threads don't spawn one Chromium process per message) into
the HTML string the web view loads. Plain text is escaped and quote lines
marked; the cid: rewrite is namespaced per message ("<prefix>!<id>") so
two thread messages sharing a Content-ID don't collide.
Hardened namespaceCids beyond the initial sketch after attacking it:
handles unquoted cid: attribute values, background=/poster= (not just
src/href), and CSS url(cid:...) in both style="" attributes and <style>
blocks, all case-insensitively. Replaced the greedy [^"']+ capture with
per-quote-style alternation so two cid: refs on one line can't bleed into
each other.
CidSchemeHandler serves cid: requests from the thread's inline-parts map,
keyed by the same namespaced string, replaced wholesale per thread.
|
