* Add a `Transaction::version` getter
Returns the version of the transaction as a `u32`.
* Add `Transaction::is_overwintered` helper method
Returns if the `fOverwintered` flag should be set for the transaction's
version.
* Use new helpers to serialize transaction version
Reduce the repeated code and make it less error-prone with future
changes.
* Add getter methods to `transaction::Request` type
Refactor to move the type deconstruction code into the `Request` type.
The main objective is to make it easier to split the call handler into
methods that receive the request directly.
* Refactor to create `verify_v4_transaction` helper
Split the code specific to V4 transactions into a separate helper
method.
* Create `verify_v5_transaction` helper method
Prepare a separate method to have the validation code.
* Add `UnsupportedByNetworkUpgrade` error variant
An error for when a transaction's version isn't supported by the network
upgrade of the block it's included or for the current network upgrade if
the transaction is for the mempool.
* Verify a V5 transaction's network upgrade
For now, only NU5 supports V5 transactions.
* Test that V5 transaction is rejected on Canopy
Create a fake V5 transaction and try to verify it using a block height
from Canopy's activation. The verifier should reject the transaction
with an error saying that the network upgrade does not support that
transaction version.
* Test if V5 tx. is accepted after NU5 activation
Create a fake V5 transaction and pretend it is placed in a block that
has a height after the NU5 activation. The test should succeed, but
since the NU5 activation height has not been specified yet (neither for
the testnet nor the mainnet), for now this test is marked as
`should_panic`.
* Add `TODO` comment to the code
Add more detail to what's left to do, and link to the appropriate PRs.
* Use `u32` to store transaction version
Use a type consistent with how the version is specified.
Co-authored-by: teor <teor@riseup.net>
Co-authored-by: teor <teor@riseup.net>