Add SCRIPT_VERIFY_MINIMALDATA (BIP62 rules 3 and 4)

Also use the new flag as a standard rule, and replace the IsCanonicalPush
standardness check with it (as it is more complete).

1 files changed, 11 insertions, 7 deletions

diff --git a/src/script/script.h b/src/script/script.h
index 706a85a29b..e97967dcea 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -192,10 +192,14 @@ public:
         m_value = n;
     }
 
-    explicit CScriptNum(const std::vector<unsigned char>& vch)
+    explicit CScriptNum(const std::vector<unsigned char>& vch, bool fRequireMinimal)
     {
-        if (vch.size() > nMaxNumSize)
-            throw scriptnum_error("CScriptNum(const std::vector<unsigned char>&) : overflow");
+        if (vch.size() > nMaxNumSize) {
+            throw scriptnum_error("script number overflow");
+        }
+        if (fRequireMinimal && vch.size() > 0 && (vch.back() & 0x7f) == 0 && (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0)) {
+            throw scriptnum_error("non-minimally encoded script number");
+        }
         m_value = set_vch(vch);
     }
 
@@ -319,7 +323,6 @@ private:
     int64_t m_value;
 };
 
-
 /** Serialized script, used inside transaction inputs and outputs */
 class CScript : public std::vector<unsigned char>
 {
@@ -330,6 +333,10 @@ protected:
         {
             push_back(n + (OP_1 - 1));
         }
+        else if (n == 0)
+        {
+            push_back(OP_0);
+        }
         else
         {
             *this << CScriptNum::serialize(n);
@@ -554,9 +561,6 @@ public:
     // Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it consensus-critical).
     bool IsPushOnly() const;
 
-    // Called by IsStandardTx.
-    bool HasCanonicalPushes() const;
-
     // Returns whether the script is guaranteed to fail at execution,
     // regardless of the initial stack. This allows outputs to be pruned
     // instantly when entering the UTXO set.