Disallow using addresses in createmultisig

Make createmultisig only accept public keys with the old functionality
marked as deprecated.

Splits _createmultisig_redeemscript into two functions, one for
getting public keys from UniValue and one for getting addresses
from UniValue and then their respective public keys. The one for
retrieving address's public keys is located in rpcwallet.cpp

Changes addwitnessaddress's output to be a JSON object with
two fields, address and redeemscript.

Adds a test to deprecated_rpc.py for testing the deprecation.

Update the tests to use addwitnessaddress or give only public keys
to createmultisig. Anything that used addwitnessaddress was also
updated to reflect the new API.

1 files changed, 32 insertions, 77 deletions

diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 95a27d474b..62bcdea31c 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -15,6 +15,7 @@
 #include <netbase.h>
 #include <rpc/blockchain.h>
 #include <rpc/server.h>
+#include <rpc/util.h>
 #include <timedata.h>
 #include <util.h>
 #include <utilstrencodings.h>
@@ -254,88 +255,21 @@ UniValue validateaddress(const JSONRPCRequest& request)
 // Needed even with !ENABLE_WALLET, to pass (ignored) pointers around
 class CWallet;
 
-/**
- * Used by addmultisigaddress / createmultisig:
- */
-CScript _createmultisig_redeemScript(CWallet * const pwallet, const UniValue& params)
-{
-    int nRequired = params[0].get_int();
-    const UniValue& keys = params[1].get_array();
-
-    // Gather public keys
-    if (nRequired < 1)
-        throw std::runtime_error("a multisignature address must require at least one key to redeem");
-    if ((int)keys.size() < nRequired)
-        throw std::runtime_error(
-            strprintf("not enough keys supplied "
-                      "(got %u keys, but need at least %d to redeem)", keys.size(), nRequired));
-    if (keys.size() > 16)
-        throw std::runtime_error("Number of addresses involved in the multisignature address creation > 16\nReduce the number");
-    std::vector<CPubKey> pubkeys;
-    pubkeys.resize(keys.size());
-    for (unsigned int i = 0; i < keys.size(); i++)
-    {
-        const std::string& ks = keys[i].get_str();
-#ifdef ENABLE_WALLET
-        // Case 1: Bitcoin address and we have full public key:
-        CTxDestination dest = DecodeDestination(ks);
-        if (pwallet && IsValidDestination(dest)) {
-            CKeyID key = GetKeyForDestination(*pwallet, dest);
-            if (key.IsNull()) {
-                throw std::runtime_error(strprintf("%s does not refer to a key", ks));
-            }
-            CPubKey vchPubKey;
-            if (!pwallet->GetPubKey(key, vchPubKey)) {
-                throw std::runtime_error(strprintf("no full public key for address %s", ks));
-            }
-            if (!vchPubKey.IsFullyValid())
-                throw std::runtime_error(" Invalid public key: "+ks);
-            pubkeys[i] = vchPubKey;
-        }
-
-        // Case 2: hex public key
-        else
-#endif
-        if (IsHex(ks))
-        {
-            CPubKey vchPubKey(ParseHex(ks));
-            if (!vchPubKey.IsFullyValid())
-                throw std::runtime_error(" Invalid public key: "+ks);
-            pubkeys[i] = vchPubKey;
-        }
-        else
-        {
-            throw std::runtime_error(" Invalid public key: "+ks);
-        }
-    }
-    CScript result = GetScriptForMultisig(nRequired, pubkeys);
-
-    if (result.size() > MAX_SCRIPT_ELEMENT_SIZE)
-        throw std::runtime_error(
-                strprintf("redeemScript exceeds size limit: %d > %d", result.size(), MAX_SCRIPT_ELEMENT_SIZE));
-
-    return result;
-}
-
 UniValue createmultisig(const JSONRPCRequest& request)
 {
-#ifdef ENABLE_WALLET
-    CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
-#else
-    CWallet * const pwallet = nullptr;
-#endif
-
     if (request.fHelp || request.params.size() < 2 || request.params.size() > 2)
     {
         std::string msg = "createmultisig nrequired [\"key\",...]\n"
             "\nCreates a multi-signature address with n signature of m keys required.\n"
             "It returns a json object with the address and redeemScript.\n"
-
+            "DEPRECATION WARNING: Using addresses with createmultisig is deprecated. Clients must\n"
+            "transition to using addmultisigaddress to create multisig addresses with addresses known\n"
+            "to the wallet before upgrading to v0.17. To use the deprecated functionality, start bitcoind with -deprecatedrpc=createmultisig\n"
             "\nArguments:\n"
-            "1. nrequired      (numeric, required) The number of required signatures out of the n keys or addresses.\n"
-            "2. \"keys\"       (string, required) A json array of keys which are bitcoin addresses or hex-encoded public keys\n"
+            "1. nrequired                    (numeric, required) The number of required signatures out of the n keys or addresses.\n"
+            "2. \"keys\"                       (string, required) A json array of hex-encoded public keys\n"
             "     [\n"
-            "       \"key\"    (string) bitcoin address or hex-encoded public key\n"
+            "       \"key\"                    (string) The hex-encoded public key\n"
             "       ,...\n"
             "     ]\n"
 
@@ -346,16 +280,37 @@ UniValue createmultisig(const JSONRPCRequest& request)
             "}\n"
 
             "\nExamples:\n"
-            "\nCreate a multisig address from 2 addresses\n"
-            + HelpExampleCli("createmultisig", "2 \"[\\\"16sSauSf5pF2UkUwvKGq4qjNRzBZYqgEL5\\\",\\\"171sgjn4YtPu27adkKGrdDwzRTxnRkBfKV\\\"]\"") +
+            "\nCreate a multisig address from 2 public keys\n"
+            + HelpExampleCli("createmultisig", "2 \"[\\\"03789ed0bb717d88f7d321a368d905e7430207ebbd82bd342cf11ae157a7ace5fd\\\",\\\"03dbc6764b8884a92e871274b87583e6d5c2a58819473e17e107ef3f6aa5a61626\\\"]\"") +
             "\nAs a json rpc call\n"
-            + HelpExampleRpc("createmultisig", "2, \"[\\\"16sSauSf5pF2UkUwvKGq4qjNRzBZYqgEL5\\\",\\\"171sgjn4YtPu27adkKGrdDwzRTxnRkBfKV\\\"]\"")
+            + HelpExampleRpc("createmultisig", "2, \"[\\\"03789ed0bb717d88f7d321a368d905e7430207ebbd82bd342cf11ae157a7ace5fd\\\",\\\"03dbc6764b8884a92e871274b87583e6d5c2a58819473e17e107ef3f6aa5a61626\\\"]\"")
         ;
         throw std::runtime_error(msg);
     }
 
+    int required = request.params[0].get_int();
+
+    // Get the public keys
+    const UniValue& keys = request.params[1].get_array();
+    std::vector<CPubKey> pubkeys;
+    for (unsigned int i = 0; i < keys.size(); ++i) {
+        if (IsHex(keys[i].get_str()) && (keys[i].get_str().length() == 66 || keys[i].get_str().length() == 130)) {
+            pubkeys.push_back(HexToPubKey(keys[i].get_str()));
+        } else {
+#ifdef ENABLE_WALLET
+            CWallet* const pwallet = GetWalletForJSONRPCRequest(request);
+            if (IsDeprecatedRPCEnabled("createmultisig") && EnsureWalletIsAvailable(pwallet, false)) {
+                pubkeys.push_back(AddrToPubKey(pwallet, keys[i].get_str()));
+            } else
+#endif
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Invalid public key: %s\nNote that from v0.16, createmultisig no longer accepts addresses."
+            " Clients must transition to using addmultisigaddress to create multisig addresses with addresses known to the wallet before upgrading to v0.17."
+            " To use the deprecated functionality, start bitcoind with -deprecatedrpc=createmultisig", keys[i].get_str()));
+        }
+    }
+
     // Construct using pay-to-script-hash:
-    CScript inner = _createmultisig_redeemScript(pwallet, request.params);
+    CScript inner = CreateMultisigRedeemscript(required, pubkeys);
     CScriptID innerID(inner);
 
     UniValue result(UniValue::VOBJ);