[Mining] Use -miningaddress for in-wallet mining.

Replaces the hook to get a mining address from the wallet
with a retrieval of the address set as `-miningaddress`.

Performs an additional safety check at startup that the wallet
actually owns the given address.

Author: Zannick

src/init.cpp

@@ -1933,6 +1933,17 @@ bool AppInitMain()
         // Link thread groups
         LinkAutoSpendThreadGroup(&threadGroupAutoSpend);
 
+        // Validate wallet mining address.
+        std::string sAddress = gArgs.GetArg("-miningaddress", "");
+        if (!sAddress.empty()) {
+            CTxDestination dest = DecodeDestination(sAddress);
+
+            auto pt = GetMainWallet();
+            if (pt && pt->IsMine(dest) != ISMINE_SPENDABLE) {
+                return InitError(strprintf(_("Invalid -miningaddress: '%s' not owned by wallet"), sAddress));
+            }
+        }
+
         // Start wallet CPU mining if the -gen=<n> parameter is given
         int nThreads = gArgs.GetArg("-gen", 0);
         if (nThreads) {

src/wallet/wallet.cpp

@@ -4702,7 +4702,7 @@ void CWallet::MarkReserveKeysAsUsed(int64_t keypool_id)
     }
 }
 
-void CWallet::GetScriptForMining(std::shared_ptr<CReserveScript> &script)
+void CWallet::GetScriptForMiningReserveKey(std::shared_ptr<CReserveScript> &script)
 {
     std::shared_ptr<CReserveKey> rKey = std::make_shared<CReserveKey>(this);
     CPubKey pubkey;
@@ -4713,6 +4713,19 @@ void CWallet::GetScriptForMining(std::shared_ptr<CReserveScript> &script)
     script->reserveScript = CScript() << ToByteVector(pubkey) << OP_CHECKSIG;
 }
 
+void CWallet::GetScriptForMining(std::shared_ptr<CReserveScript> &script)
+{
+    std::string sAddress = gArgs.GetArg("-miningaddress", "");
+    if (!sAddress.empty()) {
+        CTxDestination dest = DecodeDestination(sAddress);
+
+        script = std::make_shared<CReserveScript>();
+        script->reserveScript = GetScriptForDestination(dest);
+        return;
+    }
+    return GetScriptForMiningReserveKey(script);
+}
+
 void CWallet::LockCoin(const COutPoint& output)
 {
     AssertLockHeld(cs_wallet); // setLockedCoins

src/wallet/wallet.h

@@ -1221,6 +1221,7 @@ class CWallet final : public CCryptoKeyStore, public CValidationInterface
 
     const std::string& GetLabelName(const CScript& scriptPubKey) const;
 
+    void GetScriptForMiningReserveKey(std::shared_ptr<CReserveScript> &script);
     void GetScriptForMining(std::shared_ptr<CReserveScript> &script);
 
     unsigned int GetKeyPoolSize() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet)