Doing so would allow an attack on old nodes, which would relay a
standard transaction spending a BIP16 output in an invalid way,
until reaching a new node, which will disconnect their peer.
Reported by makomk on IRC.
Introduce the following network rule:
* a block is not valid if it contains a transaction whose hash
already exists in the block chain, unless all that transaction's
outputs were already spent before said block.
Warning: this is effectively a network rule change, with potential
risk for forking the block chain. Leaving this unfixed carries the
same risk however, for attackers that can cause a reorganisation
in part of the network.
Thanks to Russell O'Connor and Ben Reeves.
Allow mining of min-difficulty blocks if 20 minutes have gone by without mining a regular-difficulty block.
Normal rules apply every 2016 blocks, though, so there may be a very-slow-to-confirm block at the difficulty-adjustment blocks.
During the rushed transition from 0.01 BTC to 0.0005 BTC fees, we took the
approach of dropping the relay and block-inclusion fee to 0.0005 BTC
immediately, and only delayed adjusting the sending fee for the next release.
Afterward, the relay fee was lowered to 0.0001 BTC to avoid having the same
problem in the future. However, the block inclusion code was left setting
fForRelay to true! This fixes that, so the lower 0.0001 BTC allowance is (as
intended) only permitted for real relaying.
Collapsed multiple wallet mutexes to a single cs_wallet, to avoid deadlocks with wallet methods that acquired locks in different order.
Also change master RPC call handler to acquire cs_main and cs_wallet locks before executing RPC calls; requiring each RPC call to acquire the right set of locks in the right order was too error-prone.
Explicitly make these global variables less-global to reduce the maximum
scope of this global state.
In my experience global variables tend to be a major source of bugs. As
such the less accessible they are the less likely they are to be the
source of a bug.
Signed-off-by: Giel van Schijndel <me@mortis.eu>
Regarding https://bitcointalk.org/index.php?topic=28022.0
main.cpp has: "char pchMessageStart[4] = { 0xf9, 0xbe, 0xb4, 0xd9 };"
Per discussion on the thread linked, leaving the signedness of
pchMessageStart is unsafe for values > 0x80. This patch specifies
'unsigned char' in main.cpp and net.h.
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Previously, mapAlreadyAskedFor was read from, but never added to.
The original intent was to use mapAlreadyAskedFor to keep track
of the time an item was requested and "Each retry is 2 minutes
after the last".
This implements that intent.
In the assert()s take advantage of the fact that string constants
("string") are effectively of type 'const char []', which when used in
an expression yield a non-NULL pointer.
An assertion that should always fail can thus be formulated as:
assert(!"fail);
An assertion where a text message should be added to the expression can
be written as such:
assert("message" && expression);
Signed-off-by: Giel van Schijndel <me@mortis.eu>
This commit adds support for ckeys, or enCrypted private keys, to the wallet.
All keys are stored in memory in their encrypted form and thus the passphrase
is required from the user to spend coins, or to create new addresses.
Keys are encrypted with AES-256-CBC using OpenSSL's EVP library. The key is
calculated via EVP_BytesToKey using SHA512 with (by default) 25000 rounds and
a random salt.
By default, the user's wallet remains unencrypted until they call the RPC
command encryptwallet <passphrase> or, from the GUI menu, Options->
Encrypt Wallet.
When the user is attempting to call RPC functions which require the password
to unlock the wallet, an error will be returned unless they call
walletpassphrase <passphrase> <time to keep key in memory> first.
A keypoolrefill command has been added which tops up the users keypool
(requiring the passphrase via walletpassphrase first).
keypoolsize has been added to the output of getinfo to show the user the
number of keys left before they need to specify their passphrase (and call
keypoolrefill).
Note that walletpassphrase will automatically fill keypool in a separate
thread which it spawns when the passphrase is set. This could cause some
delays in other threads waiting for locks on the wallet passphrase, including
one which could cause the passphrase to be stored longer than expected,
however it will not allow the passphrase to be used longer than expected as
ThreadCleanWalletPassphrase will attempt to get a lock on the key as soon
as the specified lock time has arrived.
When the keypool runs out (and wallet is locked) GetOrReuseKeyFromPool
returns vchDefaultKey, meaning miners may start to generate many blocks to
vchDefaultKey instead of a new key each time.
A walletpassphrasechange <oldpassphrase> <newpassphrase> has been added to
allow the user to change their password via RPC.
Whenever keying material (unencrypted private keys, the user's passphrase,
the wallet's AES key) is stored unencrypted in memory, any reasonable attempt
is made to mlock/VirtualLock that memory before storing the keying material.
This is not true in several (commented) cases where mlock/VirtualLocking the
memory is not possible.
Although encryption of private keys in memory can be very useful on desktop
systems (as some small amount of protection against stupid viruses), on an
RPC server, the password is entered fairly insecurely. Thus, the only main
advantage encryption has for RPC servers is for RPC servers that do not spend
coins, except in rare cases, eg. a webserver of a merchant which only receives
payment except for cases of manual intervention.
Thanks to jgarzik for the original patch and sipa, gmaxwell and many others
for all their input.
Conflicts:
src/wallet.cpp
Introduce SendBufferSize() and ReceiveBufferSize(), and limit
the blocks sent as response to the "getblocks" message to
half of the active send buffer size.
