When a serialized length refers to an array of structures, the trivial
DOS prevention can be out by a factor of sizeof(serialized struct). Use
the size of the serialized structure as a multiplier to prevent this.
Transaction inputs are the motivating example, where the check is out by
a factor of ~40.
If no witnesses are present on any inputs, then extended serialisation
should not be used.
[ Amended to make adding new flags clearer in future -- RR ]
Signed-off-by: Jon Griffiths <jon_p_griffiths@yahoo.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The deserialization of bitcoin transactions in wire/ is rather
annoying in that we first allocate a new bitcoin_tx, then copy it's
contents onto the destination and then still carry the newly allocated
one around due to the tal-tree. This splits `pull_bitcoin_tx` into
two: one part that does the allocation and another one that proceeds
to parse.
Signed-off-by: Christian Decker <decker.christian@gmail.com>
It's just a sha256_double, but importantly when we convert it to a
string (in type_to_string, which is used in logging) we use
bitcoin_txid_to_hex() so it's reversed as people expect.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
To avoid everything pulling in HTLCs stuff to the opening daemon, we
split the channel and commit_tx routines into initial_channel and
initial_commit_tx (no HTLC support) and move full HTLC supporting versions
into channeld.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The signing code asserts these are NULL, and if we unmarshal from the
wire then sign them, it gets upset.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
From doing a code walkthrough with Christian Decker; unnecessary const in
bitcoin/tx.c, an erroneous FIXME, a missing comment, and an unused struct.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
BIP141 indicates that the rule for block size has changed: witness
bytes effectively count for 1, and non-witness bytes count for 4, but
the maximum total has increased to 4,000,000.
This means that fee estimates should use the witness cost (divided by
4), not the raw txlen.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We currently linearize and then measure the string; this is better since
we're about to do it in a second place.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We need this for signing segwitness txs. Unfortunately, we don't have it
for transactions we received as hex, only ones we created; to make this safe
we use a pointer which is NULL if we don't know, and those will crash if
we try to sign or check their sigs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This could only happen via our RPC interface (bitcoind should not give
us bad txs!) but it's better to be robust.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Without Alpha, it's superfluous. We're about to add segwit support,
but linearization requires a more powerful approach, and segwit
signature checking is completely different and really deserves its
own function.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I had already disabled it, and this clears the decks for Segregated Witness
which gives us everything we want.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
All the members of the transaction should be allocated off the
transaction, as they have the same lifetime.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I got confused navigating these, especially since Alpha and Bitcoin
have diverged (BIP68 was proposed after Elements Alpha).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The format for both the nSequence field and the stack arg for
OP_CHECKSEQUENCEVERIFY is either:
Time-relative: [Bit 22 = 1] 00000 <time-shifted-by-9>
Block-relative: [Bit 22 = 0] 00000 <number of blocks>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The latest version of the BIP doesn't use inversion, but does use
bitshifts.
It also uncovered a bug in the test scripts: the block timestamps
creep forward when we generate large numbers of blocks (UpdateTime
insists it be > GetMedianTimePast() so it's valid). We need to take
this into account when waiting for the median to move (reduced it from
60 to 30 seconds, since that adds about 14 seconds).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It doesn't matter until we start setting sequence numbers properly,
so hasn't been noticed until now.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Otherwise valgrind tells you when you test a hash; you want to
know if you hash uninitialized memory long before that.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
practicalswift
Rusty Russell
Jon Griffiths
Christian Decker
Jacob