9153ff3e27 rpc: add non-regression test about deriveaddresses crash when index is 2147483647 (muxator)
addf9d6502 rpc: fix crash in deriveaddresses when derivation index is 2147483647 (muxator)
Pull request description:
This PR is a proposal for fixing #26274 (better described there).
The problem is due to a signed int wrapping when the `index` parameter of the `deriveaddresses` RPC call has the value `2^31-1`.
```C++
for (int i = range_begin; i <= range_end; ++i) {
```
* the first commit adds a "temporary" test case (`test/functional/rpc_deriveaddresses_crash.py`) that shows the crash, and can be used to generate a core dump;
* the second commit fixes the problem giving an explicit size to the `i` variable in a for loop, from `int` to `int64_t`. The same commit also removes the ephemeral test case and adds a passing test to `test/functional/rpc_deriveaddresses.py`, in order to prevent future regressions.
This is my first submission to this project and I do not know its conventions. Please advise if something needs to be changed.
ACKs for top commit:
achow101:
ACK 9153ff3e27
Tree-SHA512: 0477b57b15dc2c682cf539d6002f100d44a8c7e668041aa3340c39dcdbd40e083c75dec6896b6c076b044a01c2e5254272ae6696d8a1467539391926f270940a
cf288377c0