Make and get the multisig redeemscript and destination in one function instead of two

Instead of creating a redeemScript with CreateMultisigRedeemscript and
then getting the destination with AddAndGetDestinationForScript, do
both in the same function.

CreateMultisigRedeemscript is changed to AddAndGetMultisigDestination.
It creates the redeemScript and returns it via an output parameter. Then
it calls AddAndGetDestinationForScript to add the destination to the
keystore and get the proper destination.

This allows us to inspect the public keys in the redeemScript before creating
the destination so that the correct destination is used when uncompressed
pubkeys are in the multisig.

Github-Pull: #16026
Rebased-From: a49503402b6bc21e3878e151c07529941d36aed0

3 files changed, 22 insertions, 9 deletions

diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 0a97f80297..780a10e03f 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -128,9 +128,9 @@ static UniValue createmultisig(const JSONRPCRequest& request)
     }
 
     // Construct using pay-to-script-hash:
-    const CScript inner = CreateMultisigRedeemscript(required, pubkeys);
     CBasicKeyStore keystore;
-    const CTxDestination dest = AddAndGetDestinationForScript(keystore, inner, output_type);
+    CScript inner;
+    const CTxDestination dest = AddAndGetMultisigDestination(required, pubkeys, output_type, keystore, inner);
 
     UniValue result(UniValue::VOBJ);
     result.pushKV("address", EncodeDestination(dest));
diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index 40ac133186..ff832810bc 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -5,6 +5,7 @@
 #include <key_io.h>
 #include <keystore.h>
 #include <policy/fees.h>
+#include <outputtype.h>
 #include <rpc/util.h>
 #include <tinyformat.h>
 #include <util/strencodings.h>
@@ -46,8 +47,8 @@ CPubKey AddrToPubKey(CKeyStore* const keystore, const std::string& addr_in)
     return vchPubKey;
 }
 
-// Creates a multisig redeemscript from a given list of public keys and number required.
-CScript CreateMultisigRedeemscript(const int required, const std::vector<CPubKey>& pubkeys)
+// Creates a multisig address from a given list of public keys, number of signatures required, and the address type
+CTxDestination AddAndGetMultisigDestination(const int required, const std::vector<CPubKey>& pubkeys, OutputType type, CKeyStore& keystore, CScript& script_out)
 {
     // Gather public keys
     if (required < 1) {
@@ -60,13 +61,24 @@ CScript CreateMultisigRedeemscript(const int required, const std::vector<CPubKey
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Number of keys involved in the multisignature address creation > 16\nReduce the number");
     }
 
-    CScript result = GetScriptForMultisig(required, pubkeys);
+    script_out = GetScriptForMultisig(required, pubkeys);
 
-    if (result.size() > MAX_SCRIPT_ELEMENT_SIZE) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, (strprintf("redeemScript exceeds size limit: %d > %d", result.size(), MAX_SCRIPT_ELEMENT_SIZE)));
+    if (script_out.size() > MAX_SCRIPT_ELEMENT_SIZE) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, (strprintf("redeemScript exceeds size limit: %d > %d", script_out.size(), MAX_SCRIPT_ELEMENT_SIZE)));
     }
 
-    return result;
+    // Check if any keys are uncompressed. If so, the type is legacy
+    for (const CPubKey& pk : pubkeys) {
+        if (!pk.IsCompressed()) {
+            type = OutputType::LEGACY;
+            break;
+        }
+    }
+
+    // Make the address
+    CTxDestination dest = AddAndGetDestinationForScript(keystore, script_out, type);
+
+    return dest;
 }
 
 class DescribeAddressVisitor : public boost::static_visitor<UniValue>
diff --git a/src/rpc/util.h b/src/rpc/util.h
index f1bd2c89df..d4d8694053 100644
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -6,6 +6,7 @@
 #define BITCOIN_RPC_UTIL_H
 
 #include <node/transaction.h>
+#include <outputtype.h>
 #include <pubkey.h>
 #include <rpc/protocol.h>
 #include <script/standard.h>
@@ -28,7 +29,7 @@ extern InitInterfaces* g_rpc_interfaces;
 
 CPubKey HexToPubKey(const std::string& hex_in);
 CPubKey AddrToPubKey(CKeyStore* const keystore, const std::string& addr_in);
-CScript CreateMultisigRedeemscript(const int required, const std::vector<CPubKey>& pubkeys);
+CTxDestination AddAndGetMultisigDestination(const int required, const std::vector<CPubKey>& pubkeys, OutputType type, CKeyStore& keystore, CScript& script_out);
 
 UniValue DescribeAddress(const CTxDestination& dest);