The CTxUndo class encapsulates data necessary to undo the effects of
a transaction on the txout set, namely the previous outputs consumed
by it (script + amount), and potentially transaction meta-data when
it is spent entirely.
The CCoins class represents a pruned set of transaction outputs from
a given transaction. It only retains information about its height in
the block chain, whether it was a coinbase transaction, and its
unspent outputs (script + amount).
It has a custom serializer that has very low redundancy.
Special serializer/deserializer for amount values. It is optimized for
values which have few non-zero digits in decimal representation. Most
amounts currently in the txout set take only 1 or 2 bytes to
represent.
Special serializers for script which detect common cases and encode
them much more efficiently. 3 special cases are defined:
* Pay to pubkey hash (encoded as 21 bytes)
* Pay to script hash (encoded as 21 bytes)
* Pay to pubkey starting with 0x02, 0x03 or 0x04 (encoded as 33 bytes)
Other scripts up to 121 bytes require 1 byte + script length. Above
that, scripts up to 16505 bytes require 2 bytes + script length.
Variable-length integers: bytes are a MSB base-128 encoding of the number.
The high bit in each byte signifies whether another digit follows. To make
the encoding is one-to-one, one is subtracted from all but the last digit.
Thus, the byte sequence a[] with length len, where all but the last byte
has bit 128 set, encodes the number:
(a[len-1] & 0x7F) + sum(i=1..len-1, 128^i*((a[len-i-1] & 0x7F)+1))
Properties:
* Very small (0-127: 1 byte, 128-16511: 2 bytes, 16512-2113663: 3 bytes)
* Every integer has exactly one encoding
* Encoding does not depend on size of original integer type
This reverts commit 199d88cf90, reversing
changes made to 65bc1573e7.
License is worse instead of better. Will only accept public domain and
MIT-licensed icons from now on.
- this patch enables several new GCC compiler hardening options that
allows us to increase the security of our binaries (see:
https://wiki.debian.org/Hardening)
-D_FORTIFY_SOURCE=2:
Enables compile-time protection against static sized buffer overflows.
-Wl,-z,relro -Wl,-z,now:
Enables full RELRO (RELocation Read-Only), which is a generic mitigation
technique to harden the data sections of an ELF binary/process. See:
http://isisblogs.poly.edu/2011/06/01/relro-relocation-read-only/ for
further details.
Corrupt wallets used to cause a DB_RUNRECOVERY uncaught exception and a
crash. This commit does three things:
1) Runs a BDB verify early in the startup process, and if there is a
low-level problem with the database:
+ Moves the bad wallet.dat to wallet.timestamp.bak
+ Runs a 'salvage' operation to get key/value pairs, and
writes them to a new wallet.dat
+ Continues with startup.
2) Much more tolerant of serialization errors. All errors in deserialization
are reported by tolerated EXCEPT for errors related to reading keypairs
or master key records-- those are reported and then shut down, so the user
can get help (or recover from a backup).
3) Adds a new -salvagewallet option, which:
+ Moves the wallet.dat to wallet.timestamp.bak
+ extracts ONLY keypairs and master keys into a new wallet.dat
+ soft-sets -rescan, to recreate transaction history
This was tested by randomly corrupting testnet wallets using a little
python script I wrote (https://gist.github.com/3812689)
Before, opening a -datadir that was created with a new
version of Berkeley DB would result in an un-caught DB_RUNRECOVERY
exception.
After these changes, the error is caught and the user is told
that there is a problem and is told how to try to recover from
it.
Before, opening a -datadir that was created with a new
version of Berkeley DB would result in an un-caught DB_RUNRECOVERY
exception.
After these changes, the error is caught and the user is told
that there is a problem and is told how to try to recover from
it.
