rpc: Move the `generate` RPC call to rpcwallet

This makes it possible to mine to any wallet when multi-wallet mode is added.
Solves the same problem as #10649, but IMO in a cleaner way.

It also gets rid of the circuitous `ScriptForMining` method on
`CValidationInterface`, which really doesn't belong there.

After this change it's still possible to mine without wallet through
`generatetoaddress`.

2 files changed, 45 insertions, 1 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 5bbb5088e2..93d3920d21 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -15,6 +15,7 @@
 #include "policy/fees.h"
 #include "policy/policy.h"
 #include "policy/rbf.h"
+#include "rpc/mining.h"
 #include "rpc/server.h"
 #include "script/sign.h"
 #include "timedata.h"
@@ -2922,6 +2923,47 @@ UniValue bumpfee(const JSONRPCRequest& request)
     return result;
 }
 
+UniValue generate(const JSONRPCRequest& request)
+{
+    CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
+
+    if (!EnsureWalletIsAvailable(pwallet, request.fHelp))
+        return NullUniValue;
+
+    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
+        throw std::runtime_error(
+            "generate nblocks ( maxtries )\n"
+            "\nMine up to nblocks blocks immediately (before the RPC call returns) to an address in the wallet.\n"
+            "\nArguments:\n"
+            "1. nblocks      (numeric, required) How many blocks are generated immediately.\n"
+            "2. maxtries     (numeric, optional) How many iterations to try (default = 1000000).\n"
+            "\nResult:\n"
+            "[ blockhashes ]     (array) hashes of blocks generated\n"
+            "\nExamples:\n"
+            "\nGenerate 11 blocks\n"
+            + HelpExampleCli("generate", "11")
+        );
+
+    int nGenerate = request.params[0].get_int();
+    uint64_t nMaxTries = 1000000;
+    if (request.params.size() > 1) {
+        nMaxTries = request.params[1].get_int();
+    }
+
+    std::shared_ptr<CReserveScript> coinbaseScript;
+    pwallet->GetScriptForMining(coinbaseScript);
+
+    // If the keypool is exhausted, no script is returned at all.  Catch this.
+    if (!coinbaseScript)
+        throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
+
+    //throw an error if no script was provided
+    if (coinbaseScript->reserveScript.empty())
+        throw JSONRPCError(RPC_INTERNAL_ERROR, "No coinbase script available (mining requires a wallet)");
+
+    return generateBlocks(coinbaseScript, nGenerate, nMaxTries, true);
+}
+
 extern UniValue abortrescan(const JSONRPCRequest& request); // in rpcdump.cpp
 extern UniValue dumpprivkey(const JSONRPCRequest& request); // in rpcdump.cpp
 extern UniValue importprivkey(const JSONRPCRequest& request);
@@ -2985,6 +3027,8 @@ static const CRPCCommand commands[] =
     { "wallet",             "walletpassphrasechange",   &walletpassphrasechange,   true,   {"oldpassphrase","newpassphrase"} },
     { "wallet",             "walletpassphrase",         &walletpassphrase,         true,   {"passphrase","timeout"} },
     { "wallet",             "removeprunedfunds",        &removeprunedfunds,        true,   {"txid"} },
+
+    { "generating",         "generate",                 &generate,                 true,   {"nblocks","maxtries"} },
 };
 
 void RegisterWalletRPCCommands(CRPCTable &t)
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 6ed955cf58..2af61b1aa5 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -1025,7 +1025,7 @@ public:
         }
     }
 
-    void GetScriptForMining(std::shared_ptr<CReserveScript> &script) override;
+    void GetScriptForMining(std::shared_ptr<CReserveScript> &script);
     
     unsigned int GetKeyPoolSize()
     {