f6b7fc349c Support h instead of ' in hardened descriptor paths (Pieter Wuille)
fddea672eb Add experimental warning to scantxoutset (Jonas Schnelli)
6495849bfd [QA] Extend tests to more combinations (Pieter Wuille)
1af237faef [QA] Add xpub range tests in scantxoutset tests (Jonas Schnelli)
151600bb49 Swap in descriptors support into scantxoutset (Pieter Wuille)
0652c3284f Descriptor tests (Pieter Wuille)
fe8a7dcd78 Output descriptors module (Pieter Wuille)
e54d76044b Add simple FlatSigningProvider (Pieter Wuille)
29943a904a Add more methods to Span class (Pieter Wuille)
Pull request description:
As promised, here is an implementation of my output descriptor concept (https://gist.github.com/sipa/e3d23d498c430bb601c5bca83523fa82) and integration within the `scantxoutset` RPC that was just added through #12196.
It changes the RPC to use descriptors for everything; I hope the interface is simple enough to encompass all use cases. It includes support for P2PK, P2PKH, P2WPKH, P2SH, P2WSH, multisig, xpubs, xprvs, and chains of keys - combined in every possible way.
Tree-SHA512: 63b54a96e7a72f5b04a8d645b8517d43ecd6a65a41f9f4e593931ce725a8845ab0baa1e9db6a7243190d8ac841f6e7e2f520d98c539312d78f7fd687d2c7b88f
ac8a1d092e [RPC] Remove field in getblocktemplate help that has never been used (Conor Scott)
Pull request description:
[BIP 22 - getblocktemplate](https://github.com/bitcoin/bips/blob/master/bip-0022.mediawiki#Transactions%20Object%20Format) specifies an optional flag, `required` if the transaction must be in the block.
Luke's implementation #936 did not include this flag, and it was later added to the help description in #3246 (more than a year later) but the field was still never actually implemented. As far as I can tell, bitcoin core would have never actually included this in a `getblocktemplate` call, so it seems logical to remove it from the help description.
If I am missing something or this is considered harmless - I can close the PR.
Tree-SHA512: f25dda51cc4e1512aff69309be04e3053bdccc1cf03c8d58e8866aa1fdf9d86cc57df872e85528351fc8a8d6d64a8f46a36c513680834762d854f368fbeb0f44
a3fa4d6a6a QA: Fix bug in -usecli logic that converts booleans to non-lowercase strings (Jonas Schnelli)
4704e5f074 [QA] add createwallet disableprivatekey test (Jonas Schnelli)
c7b8f343e9 [Qt] Disable creating receive addresses when private keys are disabled (Jonas Schnelli)
2f15c2bc20 Add disable privatekeys option to createwallet (Jonas Schnelli)
cebefba085 Add option to disable private keys during internal wallet creation (Jonas Schnelli)
9995a602a6 Add facility to store wallet flags (64 bits) (Jonas Schnelli)
Pull request description:
This mode ('createwallet {"disableprivatekeys": true}') is intended for a sane pure watch-only mode, ideal for a use-case where one likes to use Bitcoin-Core in conjunction with a hardware-wallet or another solutions for cold-storage.
Since we have support for custom change addresses in `fundrawtransaction`, pure watch-only wallets including coin-selection are possible and do make sense for some use cases.
This new mode disables all forms of private key generation and ensure that no mix between hot and cold keys are possible.
Tree-SHA512: 3ebe7e8d54c4d4e5f790c348d4c292d456f573960a5b04d69ca5ef43a9217c7e7671761c6968cdc56f9a8bc235f3badd358576651af9f10855a0eb731f3fc508
020628e3a4 Tests for PSBT (Andrew Chow)
a4b06fb42e Create wallet RPCs for PSBT (Andrew Chow)
c27fe419ef Create utility RPCs for PSBT (Andrew Chow)
8b5ef27937 SignPSBTInput wrapper function (Andrew Chow)
58a8e28918 Refactor transaction creation and transaction funding logic (Andrew Chow)
e9d86a43ad Methods for interacting with PSBT structs (Andrew Chow)
12bcc64f27 Add pubkeys and whether input was witness to SignatureData (Andrew Chow)
41c607f09b Implement PSBT Structures and un/serialization methods per BIP 174 (Andrew Chow)
Pull request description:
This Pull Request fully implements the [updated](https://github.com/bitcoin/bips/pull/694) BIP 174 specification. It is based upon #13425 which implements the majority of the signing logic.
BIP 174 specifies a binary transaction format which contains the information necessary for a signer to produce signatures for the transaction and holds the signatures for an input while the input does not have a complete set of signatures.
This PR contains structs for PSBT, serialization, and deserialzation code. Some changes to `SignatureData` have been made to support detection of UTXO type and storing public keys.
***
Many RPCs have been added to handle PSBTs.
`walletprocesspsbt` takes a PSBT format transaction, updates the PSBT with any inputs related to this wallet, signs, and finalizes the transaction. There is also an option to not sign and just update.
`walletcreatefundedpsbt` creates a PSBT from user provided data in the same form as createrawtransaction. It also funds the transaction and takes an options argument in the same form as `fundrawtransaction`. The resulting PSBT is blank with no input or output data filled in. It is analogous to a combination of `createrawtransaction` and `fundrawtransaction`
`decodepsbt` takes a PSBT and decodes it to JSON. It is analogous to `decoderawtransaction`
`combinepsbt` takes multiple PSBTs for the same tx and combines them. It is analogous to `combinerawtransaction`
`finalizepsbt` takes a PSBT and finalizes the inputs. If all inputs are final, it extracts the network serialized transaction and returns that instead of a PSBT unless instructed otherwise.
`createpsbt` is like `createrawtransaction` but for PSBTs instead of raw transactions.
`convertpsbt` takes a network serialized transaction and converts it into a psbt. The resulting psbt will lose all signature data and an explicit flag must be set to allow transactions with signature data to be converted.
***
This supersedes #12136
Tree-SHA512: 1ac7a79e5bc669933f0a6fcc93ded55263fdde9e8c144a30266b13ef9f62aacf43edd4cbca1ffbe003090b067e9643c9298c79be69d7c1b10231b32acafb6338
be98b2d9a8 [QA] Add scantxoutset test (Jonas Schnelli)
eec7cf7b33 scantxoutset: mention that scanning by address will miss P2PK txouts (Jonas Schnelli)
94d73d32ab scantxoutset: support legacy P2PK script type (Jonas Schnelli)
892de1dfea scantxoutset: add support for scripts (Jonas Schnelli)
78304941f7 Blockchain/RPC: Add scantxoutset method to scan UTXO set (Jonas Schnelli)
9048575511 Add FindScriptPubKey() to search the UTXO set (Jonas Schnelli)
Pull request description:
Alternative to #9152.
This takes `<n>` pubkeys and optionally `<n>` xpubs (together with a definable lookup windows where the default is 0-1000) and looks up common scripts in the UTXO set of all given or derived keys.
The output will be an array similar to `listunspent`. That array is compatible with `createrawtransaction` as well as with `signrawtransaction`.
This makes it possible to prepare sweeps and have them signed in a secure (cold) space.
Tree-SHA512: a2b22a117cf6e27febeb97e5d6fe30184926d50c0c7cbc77bb4121f490fed65560c52f8eac67a9720d7bf8f420efa42459768685c7e7cc03722859f51a5e1e3b
walletprocesspsbt takes a PSBT format transaction, updates the
PSBT with any inputs related to this wallet, signs, and finalizes
the transaction. There is also an option to not sign and just
update.
walletcreatefundedpsbt creates a PSBT from user provided data
in the same form as createrawtransaction. It also funds the transaction
and takes an options argument in the same form as fundrawtransaction.
The resulting PSBT is blank with no input or output data filled
in.
decodepsbt takes a PSBT and decodes it to JSON
combinepsbt takes multiple PSBTs for the same tx and combines them.
finalizepsbt takes a PSBT and finalizes the inputs. If all inputs
are final, it extracts the network serialized transaction and returns
that instead of a PSBT unless instructed otherwise.
createpsbt is like createrawtransaction but for PSBTs instead of
raw transactions.
convertpsbt takes a network serialized transaction and converts it
into a psbt. The resulting psbt will lose all signature data and
an explicit flag must be set to allow transactions with signature
data to be converted.
f40b3b82df [tests] functional test for createmultisig RPC (Anthony Towns)
b9024fdda3 segwit support for createmultisig RPC (Anthony Towns)
d58055d25f Move AddAndGetDestinationForScript from wallet to outputype module (Anthony Towns)
9a44db2e46 Add outputtype module (Anthony Towns)
Pull request description:
Adds an "address_type" parameter that accepts "legacy", "p2sh-segwit", and "bech32" to choose the type of address created. Defaults to "legacy" rather than the value of the `-address-type` option for backwards compatibility.
As part of implementing this, OutputType is moved from wallet into its own module, and `AddAndGetDestinationForScript` is changed to apply to a `CKeyStore` rather than a wallet, and to invoke `keystore.AddCScript(script)` itself rather than expecting the caller to have done that.
Fixes#12502
Tree-SHA512: a08c1cfa89976e4fd7d29caa90919ebd34a446354d17abb862e99f2ee60ed9bc19d8a21a18547c51dc3812cb9fbed86af0bef2f1e971f62bf95cade4a7d86237
685d1d8115 [tests] Check signrawtransaction* errors on missing prevtx info (Anthony Towns)
a3b065b51f Error on missing amount in signrawtransaction* (Anthony Towns)
Pull request description:
Signatures using segregated witness commit to the amount being spent, so that value must be passed into signrawtransactionwithkey and signrawtransactionwithwallet. This ensures an error is issued if that doesn't happen, rather than just assuming the value is 0 and producing a signature that is almost certainly invalid.
Based on Ben Woosley's #12458, Fixes: #12429.
Tree-SHA512: 8e2ff89d5bcf79548e569210af0d850028bc98d86c149b92207c9300ab1d63664a7e2b222c1be403a15941aa5cf36ccc3c0d570ee1c1466f3496b4fe06c17e11
d280617bf5 [qa] Add a test for merkle proof malleation (Suhas Daftuar)
ed82f17000 have verifytxoutproof check the number of txns in proof structure (Gregory Sanders)
Pull request description:
Recent publication of a weakness in Bitcoin's merkle tree construction demonstrates many SPV applications vulnerable to an expensive to pull off yet still plausible attack: https://bitslog.wordpress.com/2018/06/09/leaf-node-weakness-in-bitcoin-merkle-tree-design/
This change would at least allow `verifytxoutproof` to properly validate that the proof matches a known block, with known number of transactions any time after the full block is processed. This should neuter the attack entirely.
The negative is that a header-only processed block/future syncing mode would cause this to fail until the node has imported the data required.
related: #13451
`importprunedfunds` needs this check as well. Can expand it to cover this if people like the idea.
Tree-SHA512: 0682ec2b622a38b29f3f635323e0a8b6fc071e8a6fd134c954579926ee7b516e642966bafa667016744ce49c16e19b24dbc8801f982a36ad0a6a4aff6d93f82b
b81560029 Remove CombineSignatures and replace tests (Andrew Chow)
ed94c8b55 Replace CombineSignatures with ProduceSignature (Andrew Chow)
0422beb9b Make SignatureData able to store signatures and scripts (Andrew Chow)
b6edb4f5e Inline Sign1 and SignN (Andrew Chow)
Pull request description:
Currently CombineSignatures is used to create the final scriptSig or an input. However ProduceSignature is capable of doing this itself. Using both CombineSignatures and ProduceSignature results in code duplication which is unnecessary.
To move the scriptSig construction to ProduceSignatures, the SignatureData class contains two maps to hold pubkeys mapped to signatures, and script ids mapped to scripts. DataFromTransaction is extended to be able to extract signatures, their public keys, and scripts from existing ScriptSigs.
The SignaureData are then passed down to SignStep which can use the aforementioned maps to get the signatures, pubkeys, and scripts that it needs, falling back to the actual SigningProvider and SignatureCreator if the data are not available in the SignatureData.
Additionally, Sign1 and SignN have been removed and their functionality inlined into SignStep since Sign1 is really just a wrapper around CreateSig.
Since ProduceSignature can produce the final scriptSig or scriptWitness by using SignatureData which has extracted data from the transaction, CombineSignatures is unnecessary as ProduceSignature is able to replicate all of CombineSignatures' functionality.
This also furthers BIP 174 support and begins moving towards a BIP 174 style backend.
The tests have also been updated to use the new combining methodology.
Tree-SHA512: 78cd58a4ebe37f79229bd5eee2958a0bb45cd7f36d0e993eee13ff685b3665dd76ef2dfd5f47d34678995bb587f5594100ee5f6c09b1c69ee96d3684d470d01e
1fabd59e7 Break circular dependency: init -> * -> init by extracting shutdown.h (Ben Woosley)
e62fdfeea Drop unused init.h includes (Ben Woosley)
Pull request description:
Most includers just wanted to react to pending shutdown.
This isolates access to `fRequestShutdown` and limits access to the shutdown api functions, including the new `CancelShutdown` for setting it to `false`.
Tree-SHA512: df42f75dfbba163576710e9a67cf1228531fd99d70a2f187bfba0bcc476d6749cf88180a97e66a81bb5b6c3c7f0917de7402d26039ba7b644cb7509b02f7e267
bb582a59c Add P2WSH destination helper and use it instead of manual hashing (Pieter Wuille)
eaba1c111 Add additional unit tests for invalid IsMine combinations (Pieter Wuille)
e6b9730c4 Do not expose invalidity from IsMine (Pieter Wuille)
Pull request description:
This improves the handling of INVALID in IsMine:
* Extra INVALID conditions were added to `IsMine` (following https://github.com/bitcoin/bitcoin/pull/13142/files#r185349057), but these were untested. Add unit tests for them.
* In https://github.com/bitcoin/bitcoin/pull/13142#issuecomment-386396975 it was suggested to merge `isInvalid` into the return status. This PR takes a different approach, and removes the `isInvalid` entirely. It was only ever used inside tests, as normal users of IsMine don't care about the reason for non-mine-ness, only whether it is or not. As the unit tests are extensive enough, it seems sufficient to have a black box text (with tests for both compressed and uncompressed keys).
Some addition code simplification is done as well.
Tree-SHA512: 3267f8846f3fa4e994f57504b155b0e1bbdf13808c4c04dab7c6886c2c0b88716169cee9c5b350513297e0ca2a00812e3401acf30ac9cde5d892f9fb59ad7fef
Instead of using CombineSignatures to create the final scriptSig or
scriptWitness of an input, use ProduceSignature itself.
To allow for ProduceSignature to place signatures, pubkeys, and scripts
that it does not know about, we pass down the SignatureData to SignStep
which pulls out the information that it needs from the SignatureData.
In addition to having the scriptSig and scriptWitness, have SignatureData
also be able to store just the signatures (pubkeys mapped to sigs) and
scripts (script ids mapped to scripts).
Also have DataFromTransaction be able to extract signatures and scripts
from the scriptSig and scriptWitness of an input to put them in SignatureData.
Adds a new SignatureChecker which takes a SignatureData and puts pubkeys
and signatures into it when it successfully verifies a signature.
Adds a new field in SignatureData which stores whether the SignatureData
was complete. This allows us to also update the scriptSig and
scriptWitness to the final one when updating a SignatureData with another
one.
Signatures using segregated witness commit to the amount being spent,
so that value must be passed into signrawtransactionwithkey and
signrawtransactionwithwallet. This ensures an error is issued if that
doesn't happen, rather than just assuming the value is 0 and producing
a signature that is almost certainly invalid.
Most includers just wanted to react to pending shutdown.
This isolates access to `fRequestShutdown` and limits access to the shutdown
api functions, including the new `AbortShutdown` for setting it to `false`.
Note I originally called `AbortShutdown` `CancelShutdown` but that name was
already taken by winuser.h
https://travis-ci.org/bitcoin/bitcoin/jobs/386913329
This change also triggered a build error in bench. Fixing it required moving LIBBITCOIN_SERVER after LIBBITCOIN_WALLET in bench_bench_bitcoin_LDADD To make
server definitions in src/net.cpp available to wallet methods in
src/wallet/wallet.cpp. Specifically, solving:
libbitcoin_wallet.a(libbitcoin_wallet_a-wallet.o): In function `CWalletTx::RelayWalletTransaction(CConnman*)':
wallet.cpp:(.text+0x3f0e): undefined reference to `CConnman::NodeFullyConnected(CNode const*)'
collect2: error: ld returned 1 exit status
https://travis-ci.org/bitcoin/bitcoin/jobs/392133581
Need for remaining init.h includes confirmed via a thorough search with a more
specific regex:
\bInterrupt\(\)|\bShutdown\(\)|\bInitLogging\(\)|\bInitParameterInteraction\(\)|\bAppInitBasicSetup\(\)|\bAppInitParameterInteraction\(\)|\bAppInitSanityChecks\(\)|\bAppInitLockDataDirectory\(\)|\bAppInitMain\(\)|\bSetupServerArgs\(\)|\bLicenseInfo\(\)|g_wallet_init_interface|init.h
These were entirely unused, as based on successful compilation
and a grep for:
\bStartShutdown\(\)|\bShutdownRequested\(\)|\bInterrupt\(\)|\bShutdown\(\)|\bInitLogging\(\)|\bInitParameterInteraction\(\)|\bAppInitBasicSetup\(\)|\bAppInitParameterInteraction\(\)|\bAppInitSanityChecks\(\)|\bAppInitLockDataDirectory\(\)|\bAppInitMain\(\)|\bSetupServerArgs\(\)|\bLicenseInfo\(\)|g_wallet_init_interface|init.h
d92204c900 build: add warning to detect hidden copies in range-for loops (Cory Fields)
466e16e0e8 cleanup: avoid hidden copies in range-for loops (Cory Fields)
Pull request description:
Following-up on #13241, which was itself a follow-up of #12169.
See title. Fixing these would otherwise be a continuous process, adding the warning should keep them from cropping up.
Note that the warning seems to be Clang-only for now.
Tree-SHA512: ccfb769c3128b3f92c95715abcf21ee2496fe2aa384f80efead1529a28eeb56b98995b531b49a089f8142601389e63f7bb935963d724eacde4f5e1b4a024934b
f74894480 Only set fNewBlock to true in AcceptBlock when we write to disk (Matt Corallo)
fa6e49731 rpc: Avoid "duplicate" return value for invalid submitblock (MarcoFalke)
Pull request description:
This is #13395 with one more commit tacked on. MarcoFalke got tired of dealing with the stupidity of fixing a return code with too many rounds of review (not that I blame him). Honestly we should probably have no return whatsoever, but for now, this fixes it (as well as nLastBlockTime for eviction purposes).
Original description:
When `submitblock` of an invalid block, the return value should not be `"duplicate"`.
This is only seen when the header was previously found (denoted by the incorrectly named boolean `fBlockPresent`). Fix this bug by removing `fBlockPresent`.
Tree-SHA512: 0ce3092655d5d904b4c8c5ff7479f73ce387144a738f20472b8af132564005c6db5594ae366e589508f6258506ee7a28b1c7995a83a8328b334f99316006bf2d
9b72c988a0 scripted-diff: Avoid temporary copies when looping over std::map (Ben Woosley)
Pull request description:
The ::value_type of the std::map/std::multimap/std::unordered_map containers is
std::pair<const Key, T>. Dropping the const results in an unnecessary copy,
for example in C++11 range-based loops.
For this I started with a more general scripted diff, then narrowed it down
based on the inspection showing that all actual map/multimap/unordered_map
variables used in loops start with m or have map in the name.
Tree-SHA512: b656d66b69ffa1eb954124aa8ae2bc5436ca50262abefa93bdda55cfcdaffc5ff90cd40539051a2bd06355ba69ddf245265cc8764eebff66d761b3aec06155a9
The ::value_type of the std::map/std::multimap/std::unordered_map containers is
std::pair<const Key, T>. Dropping the const results in an unnecessary copy,
for example in C++11 range-based loops.
For this I started with a more general scripted diff, then narrowed it down
based on the inspection showing that all actual map/multimap/unordered_map
variables used in loops start with m or have map in the name.
-BEGIN VERIFY SCRIPT-
sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : m/for (\1std::pair<const \2\3 : m/' src/*.cpp src/**/*.cpp
sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : (.*)map/for (\1std::pair<const \2\3 : \4map/' src/*.cpp src/**/*.cpp
-END VERIFY SCRIPT-
67e0e04140 [wallet] [docs] Update release notes for removing `getlabeladdress` (John Newbery)
81608178cf [wallet] [rpc] Remove getlabeladdress RPC (John Newbery)
Pull request description:
labels are associated with addresses (rather than addresses being
associated with labels, as was the case with accounts). The
getlabeladdress does not make sense in this model, so remove it.
getaccountaddress is still supported for one release as the accounts
API is deprecated.
Tree-SHA512: 7f45d0456248ebcc4e54dd34e2578a09a8ea8e4fceda75238ccea9d731dc99a3f3c0519b18a9739de17d2e6e59c9c2259ba67c9ae2e3cb2a40ddb14b9193fe29
e9a1881b90 refactor: add a function for determining if a block is pruned or not (Karl-Johan Alm)
Pull request description:
The check for whether a block is pruned or not is sufficiently obscure that it deserves a macro. It is also used in 2 places, ~~with more coming, e.g. #10757~~ (turns out it was a move, not an addition).
Tree-SHA512: b9aeb60663e1d1196df5371d5aa00b32ff5d4cdea6a77e4b566f28115cce09570c18e45e4b81a4033f67c4135c8e32c027f67bae3b75c2ea4564285578a3f4dd
ebec7317ca Drop the chain argument to GetDifficulty (Ben Woosley)
Pull request description:
By dropping the chain argument to `GetDifficulty`. `GetDifficulty` was called in two ways:
* with a guaranteed non-null blockindex
* with no argument
Change the latter case to be provided `chainActive.Tip()` explicitly.
Introduced in: #11748
Tree-SHA512: f2c97014be185f3e3de92db15848548650e4a67fab20a41bcfa851c5c63c245915cbe9380f84d9da2081e8756d31a41de417db1d35cfecf41ddb4f25070eb525
6aa33feadb Drop UpdateTransaction in favor of UpdateInput (Ben Woosley)
Pull request description:
Updating the input explicitly requires the caller to present a mutable
input, which more clearly communicates the effects and intent of the call
(and, often, the enclosing loop).
In most cases, this input is already immediately available and need not be
looked up.
Tree-SHA512: 8c7914a8b7ae975d8ad0e9d760e3c5da65776a5f79d060b8ffb6b3ff7a32235f71ad705f2185b368d9263742d7796bb562395d22b806d90e8502d8c496011e57
80b4910f7d wallet: Use shared pointer to retain wallet instance (João Barbosa)
Pull request description:
Currently there are 3 places where it makes sense to retain a wallet shared pointer:
- `vpwallets`;
- `interfaces::Wallet` interface instance - used by the UI;
- wallet RPC functions - given by `GetWalletForJSONRPCRequest`.
The way it is now it is possible to have, for instance, listunspent RPC and in parallel unload the wallet (once #13111 is merged) without blocking. Once the RPC finishes, the shared pointer will release the wallet.
It is also possible to get all existing wallets without blocking because the caller keeps a local list of shared pointers.
This is mostly relevant for wallet unloading.
This PR replaces #11402.
Tree-SHA512: b7e37c7e1ab56626085afe2d40b1628e8d4f0dbda08df01b7e618ecd2d894ce9b83d4219443f444ba889096286eff002f163cb0a48f37063b62e9ba4ccfa6cce
41d0476f62 Tests: Add data file (Anthony Towns)
4cbfb6aad9 Tests: Test new getblockstats RPC (Jorge Timón)
35e77a0288 RPC: Introduce getblockstats (Jorge Timón)
cda8e36f01 Refactor: RPC: Separate GetBlockChecked() from getblock() (Jorge Timón)
Pull request description:
It returns per block statistics about several things. It should be easy to add more if people think of other things to add or remove some if I went too far (but once written, why not keep it? EDIT: answer: not to test or maintain them).
The currently available options are: minfee,maxfee,totalfee,minfeerate,maxfeerate,avgfee,avgfeerate,txs,ins,outs (EDIT: see updated list in the rpc call documentation)
For the x axis, one can use height or block.nTime (I guess I could add mediantime if there's interest [EDIT: nobody showed interest but I implemented mediantime nonetheless, in fact there's no distinction between x or y axis anymore, that's for the caller to judge]).
To calculate fees, -txindex is required.
Tree-SHA512: 2b2787a3c7dc4a11df1fce62c8a4c748f5347d7f7104205d5f0962ffec1e0370c825b49fd4d58ce8ce86bf39d8453f698bcd46206eea505f077541ca7d59b18c
This removes the need to include rpc/blockchain.cpp in order to put
GetDifficulty under test. GetDifficulty was called in two ways:
* with a guaranteed non-null blockindex
* with no argument
Change the latter case to be provided chainActive.Tip() explicitly.
