At least one service that accepted zero-confirmation transactions
was vulnerable because an attacker could send a transaction
with a lock time far in the future, and then have plenty of time in
which to get a double-spend mined (perhaps from a miner who wasn't
on the network when the first transaction was broadcast).
That is a variation on the "Finney attack". We still don't
recommend anybody accept 0-confirmation transactions as final
payment for anything. This change keeps non-final transactions
from appearing in the wallet, and, assuming most of the network
accepts this change, will prevent them from being relayed until
they are final.
- don't show QR Code context menu, when USE_QRCODE=1 was not specified
when compiling the client
- re-work on_showQRCode_clicked() for better readability and remove an
unneeded duplicate check
- re-work on_signMessage_clicked() and on_verifyMessage_clicked() to match
foreach in on_showQRCode_clicked(), which seems more robust / cleaner
- re-order context menu stuff to match real context menu layout
- add comments for all private slots in the class
Several changes to make the native windows leveldb code compile
with mingw32 and run on 32-bit Windows:
* Remove -std=c++0x dependency (modified code to use NULL instead of
nullptr)
* Link with -lshlwapi
* Only #define snprintf/etc if compiling with Visual Studio
* Do not link against DbgHelp.lib (wrote a CreateDir instead of using
DbgHelp's MakeSureDirectoryPathExists
* Define WINVER=0x0500 so MinGW32 can use the 64-bit-filesystem Windows
api calls
* Define __USE_MINGW_ANSI_STDIO=1 to use MinGW's printf (which supports
%ll)
I also cleaned up makefile.mingw, assuming that dependencies would be in
the standard /usr/local/{include,lib} by default but allowing overriding
with make DEPSDIR=... etc
This actually simplifies some SPV code, as they can keep track of
a filtered block and its txn before accepting both in one step.
The previous argument was that SPV nodes should handle the txn the
same as any other free txn and then mark them as connected to a
block when they get the filtered block itself. However, it now
appears that SPV nodes will need to put in more effort to verify
loose txn than they would to verify txn in blocks, thus making it
more approriate to send the txn after the filtered block.
Pieter Wuille