1 files changed, 29 insertions, 8 deletions
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index dc50467d3f..838e502a0a 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -1,16 +1,16 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2016 The Bitcoin Core developers
+// Copyright (c) 2009-2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "script/sign.h"
+#include <script/sign.h>
 
-#include "key.h"
-#include "keystore.h"
-#include "policy/policy.h"
-#include "primitives/transaction.h"
-#include "script/standard.h"
-#include "uint256.h"
+#include <key.h>
+#include <keystore.h>
+#include <policy/policy.h>
+#include <primitives/transaction.h>
+#include <script/standard.h>
+#include <uint256.h>
 
 
 typedef std::vector<unsigned char> valtype;
@@ -79,6 +79,7 @@ static bool SignStep(const BaseSignatureCreator& creator, const CScript& scriptP
     {
     case TX_NONSTANDARD:
     case TX_NULL_DATA:
+    case TX_WITNESS_UNKNOWN:
         return false;
     case TX_PUBKEY:
         keyID = CPubKey(vSolutions[0]).GetID();
@@ -309,6 +310,7 @@ static Stacks CombineSignatures(const CScript& scriptPubKey, const BaseSignature
     {
     case TX_NONSTANDARD:
     case TX_NULL_DATA:
+    case TX_WITNESS_UNKNOWN:
         // Don't know anything about this, assume bigger one is correct:
         if (sigs1.script.size() >= sigs2.script.size())
             return sigs1;
@@ -420,3 +422,22 @@ bool DummySignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const
     vchSig[6 + 33 + 32] = SIGHASH_ALL;
     return true;
 }
+
+bool IsSolvable(const CKeyStore& store, const CScript& script)
+{
+    // This check is to make sure that the script we created can actually be solved for and signed by us
+    // if we were to have the private keys. This is just to make sure that the script is valid and that,
+    // if found in a transaction, we would still accept and relay that transaction. In particular,
+    // it will reject witness outputs that require signing with an uncompressed public key.
+    DummySignatureCreator creator(&store);
+    SignatureData sigs;
+    // Make sure that STANDARD_SCRIPT_VERIFY_FLAGS includes SCRIPT_VERIFY_WITNESS_PUBKEYTYPE, the most
+    // important property this function is designed to test for.
+    static_assert(STANDARD_SCRIPT_VERIFY_FLAGS & SCRIPT_VERIFY_WITNESS_PUBKEYTYPE, "IsSolvable requires standard script flags to include WITNESS_PUBKEYTYPE");
+    if (ProduceSignature(creator, script, sigs)) {
+        // VerifyScript check is just defensive, and should never fail.
+        assert(VerifyScript(sigs.scriptSig, script, &sigs.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, creator.Checker()));
+        return true;
+    }
+    return false;
+}