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`.

7 files changed, 62 insertions, 44 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 9b9dd89f68..8ecd391804 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -127,6 +127,7 @@ BITCOIN_CORE_H = \
   reverselock.h \
   rpc/blockchain.h \
   rpc/client.h \
+  rpc/mining.h \
   rpc/protocol.h \
   rpc/server.h \
   rpc/register.h \
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 8c682592c5..e50742f36e 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -18,6 +18,7 @@
 #include "policy/fees.h"
 #include "pow.h"
 #include "rpc/blockchain.h"
+#include "rpc/mining.h"
 #include "rpc/server.h"
 #include "txmempool.h"
 #include "util.h"
@@ -141,42 +142,6 @@ UniValue generateBlocks(std::shared_ptr<CReserveScript> coinbaseScript, int nGen
     return blockHashes;
 }
 
-UniValue generate(const JSONRPCRequest& request)
-{
-    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)\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;
-    GetMainSignals().ScriptForMining(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);
-}
-
 UniValue generatetoaddress(const JSONRPCRequest& request)
 {
     if (request.fHelp || request.params.size() < 2 || request.params.size() > 3)
@@ -962,7 +927,6 @@ static const CRPCCommand commands[] =
     { "mining",             "getblocktemplate",       &getblocktemplate,       true,  {"template_request"} },
     { "mining",             "submitblock",            &submitblock,            true,  {"hexdata","dummy"} },
 
-    { "generating",         "generate",               &generate,               true,  {"nblocks","maxtries"} },
     { "generating",         "generatetoaddress",      &generatetoaddress,      true,  {"nblocks","address","maxtries"} },
 
     { "util",               "estimatefee",            &estimatefee,            true,  {"nblocks"} },
diff --git a/src/rpc/mining.h b/src/rpc/mining.h
new file mode 100644
index 0000000000..a148d851da
--- /dev/null
+++ b/src/rpc/mining.h
@@ -0,0 +1,15 @@
+// Copyright (c) 2017 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_RPC_MINING_H
+#define BITCOIN_RPC_MINING_H
+
+#include "script/script.h"
+
+#include <univalue.h>
+
+/** Generate blocks (mine) */
+UniValue generateBlocks(std::shared_ptr<CReserveScript> coinbaseScript, int nGenerate, uint64_t nMaxTries, bool keepScript);
+
+#endif
diff --git a/src/validationinterface.cpp b/src/validationinterface.cpp
index 46d7c9b329..be2f20b863 100644
--- a/src/validationinterface.cpp
+++ b/src/validationinterface.cpp
@@ -21,12 +21,10 @@ void RegisterValidationInterface(CValidationInterface* pwalletIn) {
     g_signals.Inventory.connect(boost::bind(&CValidationInterface::Inventory, pwalletIn, _1));
     g_signals.Broadcast.connect(boost::bind(&CValidationInterface::ResendWalletTransactions, pwalletIn, _1, _2));
     g_signals.BlockChecked.connect(boost::bind(&CValidationInterface::BlockChecked, pwalletIn, _1, _2));
-    g_signals.ScriptForMining.connect(boost::bind(&CValidationInterface::GetScriptForMining, pwalletIn, _1));
     g_signals.NewPoWValidBlock.connect(boost::bind(&CValidationInterface::NewPoWValidBlock, pwalletIn, _1, _2));
 }
 
 void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
-    g_signals.ScriptForMining.disconnect(boost::bind(&CValidationInterface::GetScriptForMining, pwalletIn, _1));
     g_signals.BlockChecked.disconnect(boost::bind(&CValidationInterface::BlockChecked, pwalletIn, _1, _2));
     g_signals.Broadcast.disconnect(boost::bind(&CValidationInterface::ResendWalletTransactions, pwalletIn, _1, _2));
     g_signals.Inventory.disconnect(boost::bind(&CValidationInterface::Inventory, pwalletIn, _1));
@@ -39,7 +37,6 @@ void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
 }
 
 void UnregisterAllValidationInterfaces() {
-    g_signals.ScriptForMining.disconnect_all_slots();
     g_signals.BlockChecked.disconnect_all_slots();
     g_signals.Broadcast.disconnect_all_slots();
     g_signals.Inventory.disconnect_all_slots();
diff --git a/src/validationinterface.h b/src/validationinterface.h
index 460aecf243..17545018df 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -40,7 +40,6 @@ protected:
     virtual void Inventory(const uint256 &hash) {}
     virtual void ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman) {}
     virtual void BlockChecked(const CBlock&, const CValidationState&) {}
-    virtual void GetScriptForMining(std::shared_ptr<CReserveScript>&) {};
     virtual void NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& block) {};
     friend void ::RegisterValidationInterface(CValidationInterface*);
     friend void ::UnregisterValidationInterface(CValidationInterface*);
@@ -72,8 +71,6 @@ struct CMainSignals {
      * callback was generated (not necessarily now)
      */
     boost::signals2::signal<void (const CBlock&, const CValidationState&)> BlockChecked;
-    /** Notifies listeners that a key for mining is required (coinbase) */
-    boost::signals2::signal<void (std::shared_ptr<CReserveScript>&)> ScriptForMining;
     /**
      * Notifies listeners that a block which builds directly on our current tip
      * has been received and connected to the headers tree, though not validated yet */
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()
     {