URL: http://bugs.freeciv.org/Ticket/Display.html?id=40299
Marko Lindqvist wrote:
URL: http://bugs.freeciv.org/Ticket/Display.html?id=40299
2008/6/22 Jason Dorje Short:
Also with utf-8 truncating things like this is not at all safe. This
can send incorrect utf-8 to the server which when sent back to the
client becomes very hard to handle. GTK will crash (yes, crash) if
given invalid utf-8; it's supposed to be checked before it's passed in
but I'm not sure if we do that. If it is checked the best thing the
client could do is discard the invalid utf-8 string.
Actually, that truncation is not needed with any correctly working
implementation of vsnprintf(). Ending zero should be there already,
and hopefully in right place UTF-8 wise.
Yes, most (all?) implementations of snprintf should truncate. But it
will NOT be in the right place utf-8 wise; snprintf knows nothing about
characters, only bytes. If truncation happens it'll be on the 50th byte
regardless of how many characters fit in there or if it gets truncated
mid-character.
But does it makes sense to send such truncated command at all. At
worst case we execute wrong variant of the command that has different
versions taking different number of parameters. At best case we are
just abbreviating something so that server still understands it.
Possibly aborting and giving the user an error message is better, yes.
For *commands* truncation shouldn't be much issue anyway as utf-8 should
generally not be used (possible exceptions being with player names or
such). For chat lines utf-8 would be the standard. Chat lines are also
limited (by packet length if nothing else) and thus some form of
truncation or filtering (discarding too-long lines) is needed. This may
be done at the client end (limiting lines to 100 letters for instance,
in GTK code) but should also be checked before such strings received
across the network are actually used (glib has a function for checking
UTF-8 string validity, for instance).
I don't know how much of this has been done, but having written most of
the encoding code I believe this is probably one area where our checks
fall short.
-jason
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