Replace invalid characters in WebChannel messages

Turns out JavaScript's JSON.stringify is not guaranteed to produce valid UTF-16
strings. It is possible in JavaScript to produce string objects which contain
invalid code units (unmatched surrogate pairs) and JSON.stringify will simply
copy this data to it's output. However, such a string cannot be losslessly
converted to UTF-8 and this leads to fun errors in WebChannelIPCTransport.

This patch

  - Adds a test for the scenario above.

  - Changes WebChannelIPCTransport to replace these invalid code units with the
    Unicode replacement character U+FFFD.

  - Changes WebChannelIPCTransportHost to validate the data it gets from the
    renderer. Not validating the data defeats the whole point of Chromium's
    fancy multi-process architecture: the renderer is not to be trusted.

  - Changes WebChannelIPCTransport to throw JavaScript exceptions for various
    errors (missing argument, wrong type, invalid JSON). Seems like the polite
    thing to do.

Task-number: QTBUG-61969
Change-Id: I83275a0eaed77109dc458b80e27217108dde9f7b
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

0 files changed, 0 insertions, 0 deletions