[RPC] Add wallet support for witness transactions (using P2SH)

Includes support for pushkeyhash wit v0 by Alex Morcos.

src/wallet/rpcwallet.cpp

@@ -1011,6 +1011,85 @@ UniValue addmultisigaddress(const UniValue& params, bool fHelp)
     return CBitcoinAddress(innerID).ToString();
 }
 
+class Witnessifier : public boost::static_visitor<bool>
+{
+public:
+    CScriptID result;
+
+    bool operator()(const CNoDestination &dest) const { return false; }
+
+    bool operator()(const CKeyID &keyID) {
+        CPubKey pubkey;
+        if (pwalletMain && pwalletMain->GetPubKey(keyID, pubkey)) {
+            CScript basescript;
+            basescript << ToByteVector(pubkey) << OP_CHECKSIG;
+            CScript witscript = GetScriptForWitness(basescript);
+            pwalletMain->AddCScript(witscript);
+            result = CScriptID(witscript);
+            return true;
+        }
+        return false;
+    }
+
+    bool operator()(const CScriptID &scriptID) {
+        CScript subscript;
+        if (pwalletMain && pwalletMain->GetCScript(scriptID, subscript)) {
+            int witnessversion;
+            std::vector<unsigned char> witprog;
+            if (subscript.IsWitnessProgram(witnessversion, witprog)) {
+                result = scriptID;
+                return true;
+            }
+            CScript witscript = GetScriptForWitness(subscript);
+            pwalletMain->AddCScript(witscript);
+            result = CScriptID(witscript);
+            return true;
+        }
+        return false;
+    }
+};
+
+UniValue addwitnessaddress(const UniValue& params, bool fHelp)
+{
+    if (!EnsureWalletIsAvailable(fHelp))
+        return NullUniValue;
+
+    if (fHelp || params.size() < 1 || params.size() > 1)
+    {
+        string msg = "addwitnessaddress \"address\"\n"
+            "\nAdd a witness address for a script (with pubkey or redeemscript known).\n"
+            "It returns the witness script.\n"
+
+            "\nArguments:\n"
+            "1. \"address\"       (string, required) An address known to the wallet\n"
+
+            "\nResult:\n"
+            "\"witnessaddress\",  (string) The value of the new address (P2SH of witness script).\n"
+            "}\n"
+        ;
+        throw runtime_error(msg);
+    }
+
+    {
+        LOCK(cs_main);
+        if (!IsWitnessEnabled(chainActive.Tip(), Params().GetConsensus())) {
+            throw JSONRPCError(RPC_WALLET_ERROR, "Segregated witness not enabled on network");
+        }
+    }
+
+    CBitcoinAddress address(params[0].get_str());
+    if (!address.IsValid())
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Bitcoin address");
+
+    Witnessifier w;
+    CTxDestination dest = address.Get();
+    bool ret = boost::apply_visitor(w, dest);
+    if (!ret) {
+        throw JSONRPCError(RPC_WALLET_ERROR, "Public key or redeemscript not known to wallet");
+    }
+
+    return CBitcoinAddress(w.result).ToString();
+}
 
 struct tallyitem
 {
@@ -2491,6 +2570,7 @@ static const CRPCCommand commands[] =
     { "hidden",             "resendwallettransactions", &resendwallettransactions, true  },
     { "wallet",             "abandontransaction",       &abandontransaction,       false },
     { "wallet",             "addmultisigaddress",       &addmultisigaddress,       true  },
+    { "wallet",             "addwitnessaddress",        &addwitnessaddress,        true  },
     { "wallet",             "backupwallet",             &backupwallet,             true  },
     { "wallet",             "dumpprivkey",              &dumpprivkey,              true  },
     { "wallet",             "dumpwallet",               &dumpwallet,               true  },