Merge pull request #5065

16d78bd Add valid invert of invalid every numeric opcode tests (Peter Todd)
2b62e17 Clearly separate PUSHDATA and numeric argument MINIMALDATA tests (Peter Todd)
dfeec18 Test every numeric-accepting opcode for correct handling of the numeric minimal encoding rule (Peter Todd)
554147a Ensure MINIMALDATA invalid tests can only fail one way (Peter Todd)
6004e77 Improve CScriptNum() comment (Peter Todd)
698c6ab Add SCRIPT_VERIFY_MINIMALDATA (BIP62 rules 3 and 4) (Pieter Wuille)
d752ba8 Add SCRIPT_VERIFY_SIGPUSHONLY (BIP62 rule 2) (Pieter Wuille)

1 files changed, 27 insertions, 8 deletions

diff --git a/src/script/script.h b/src/script/script.h
index d450db5ca..05f2e7e3a 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -192,10 +192,29 @@ 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) {
+            // Check that the number is encoded with the minimum possible
+            // number of bytes.
+            //
+            // If the most-significant-byte - excluding the sign bit - is zero
+            // then we're not minimal. Note how this test also rejects the
+            // negative-zero encoding, 0x80.
+            if ((vch.back() & 0x7f) == 0) {
+                // One exception: if there's more than one byte and the most
+                // significant bit of the second-most-significant-byte is set
+                // it would conflict with the sign bit. An example of this case
+                // is +-255, which encode to 0xff00 and 0xff80 respectively.
+                // (big-endian).
+                if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
+                    throw scriptnum_error("non-minimally encoded script number");
+                }
+            }
+        }
         m_value = set_vch(vch);
     }
 
@@ -319,7 +338,6 @@ private:
     int64_t m_value;
 };
 
-
 /** Serialized script, used inside transaction inputs and outputs */
 class CScript : public std::vector<unsigned char>
 {
@@ -330,6 +348,10 @@ protected:
         {
             push_back(n + (OP_1 - 1));
         }
+        else if (n == 0)
+        {
+            push_back(OP_0);
+        }
         else
         {
             *this << CScriptNum::serialize(n);
@@ -551,12 +573,9 @@ public:
 
     bool IsPayToScriptHash() const;
 
-    // Called by IsStandardTx and P2SH VerifyScript (which makes it consensus-critical).
+    // 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.