It is unsigned in Bitcoin Core, so the tests should match it:
The bug was introduced when the code was written in 330b0f31ee5719d94f9e52dfc83c5d82168241f9.
(Lowercase i means signed, see https://docs.python.org/3/library/struct.html#format-characters)
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This can be tested by passing a transaction with a large locktime and then observing the error:
0struct.error: 'i' format requires -2147483648 <= number <= 2147483647
746@@ -747,7 +747,7 @@ def SegwitV0SignatureMsg(script, txTo, inIdx, hashtype, amount):
747 ss += struct.pack("<q", amount)
748 ss += struct.pack("<I", txTo.vin[inIdx].nSequence)
749 ss += ser_uint256(hashOutputs)
750- ss += struct.pack("<i", txTo.nLockTime)
751+ ss += txTo.nLockTime.to_bytes(4, "little")
Could we keep the format?
0 struct.pack("<I", txTo.nLockTime)
In the instructions you’ve mentioned it’s reproducible - can you add a test that fails before this change, but passes after?
Yes, you can try this with the following diff:
0diff --git a/test/functional/p2p_segwit.py b/test/functional/p2p_segwit.py
1index d316c4b602..708e4d7e8f 100755
2--- a/test/functional/p2p_segwit.py
3+++ b/test/functional/p2p_segwit.py
4@@ -1663,6 +1663,7 @@ class SegWitTest(BitcoinTestFramework):
5 pubkeyhash = hash160(pubkey)
6 script_pkh = key_to_p2wpkh_script(pubkey)
7 tx = CTransaction()
8+ tx.nLockTime = 0xffffffff
9 tx.vin.append(CTxIn(COutPoint(temp_utxos[0].sha256, temp_utxos[0].n), b""))
10 tx.vout.append(CTxOut(temp_utxos[0].nValue, script_pkh))
11 tx.wit.vtxinwit.append(CTxInWitness())
To add a test, you may have to disable the locktime by setting the sequence number to the right value as well.
I am happy to push a commit that adds a test, if someone writes one.
can you add a test that fails before this change, but passes after?
Wouldn’t that mean that we added a test that tests the test-framework?
can you add a test that fails before this change, but passes after?
Wouldn’t that mean that we added a test that tests the test-framework?
Yes, it should be possible to write an internal python unit test to check the behavior of SegwitV0SignatureMsg. An alternative would be to extend a python functional test to cover more values of nLockTime and compare the SegwitV0SignatureMsg behavior against Bitcoin Core via the RPC interface.
nLockTime to 2147483648
