Relay OP_RETURN data TxOut as standard transaction type

src/main.cpp

@@ -497,17 +497,28 @@ bool IsStandardTx(const CTransaction& tx, string& reason)
             return false;
         }
     }
+
+    unsigned int nDataOut = 0;
+    txnouttype whichType;
     BOOST_FOREACH(const CTxOut& txout, tx.vout) {
-        if (!::IsStandard(txout.scriptPubKey)) {
+        if (!::IsStandard(txout.scriptPubKey, whichType)) {
             reason = "scriptpubkey";
             return false;
         }
-        if (txout.IsDust(CTransaction::nMinRelayTxFee)) {
+        if (whichType == TX_NULL_DATA)
+            nDataOut++;
+        else if (txout.IsDust(CTransaction::nMinRelayTxFee)) {
             reason = "dust";
             return false;
         }
     }
 
+    // only one OP_RETURN txout is permitted
+    if (nDataOut > 1) {
+        reason = "mucho-data";
+        return false;
+    }
+
     return true;
 }
 

src/script.cpp

@@ -79,6 +79,7 @@ const char* GetTxnOutputType(txnouttype t)
     case TX_PUBKEYHASH: return "pubkeyhash";
     case TX_SCRIPTHASH: return "scripthash";
     case TX_MULTISIG: return "multisig";
+    case TX_NULL_DATA: return "nulldata";
     }
     return NULL;
 }
@@ -220,6 +221,7 @@ const char* GetOpName(opcodetype opcode)
     // template matching params
     case OP_PUBKEYHASH             : return "OP_PUBKEYHASH";
     case OP_PUBKEY                 : return "OP_PUBKEY";
+    case OP_SMALLDATA              : return "OP_SMALLDATA";
 
     case OP_INVALIDOPCODE          : return "OP_INVALIDOPCODE";
     default:
@@ -1148,6 +1150,9 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, vector<vector<unsi
 
         // Sender provides N pubkeys, receivers provides M signatures
         mTemplates.insert(make_pair(TX_MULTISIG, CScript() << OP_SMALLINTEGER << OP_PUBKEYS << OP_SMALLINTEGER << OP_CHECKMULTISIG));
+
+        // Empty, provably prunable, data-carrying output
+        mTemplates.insert(make_pair(TX_NULL_DATA, CScript() << OP_RETURN << OP_SMALLDATA));
     }
 
     // Shortcut for pay-to-script-hash, which are more constrained than the other types:
@@ -1232,6 +1237,12 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, vector<vector<unsi
                 else
                     break;
             }
+            else if (opcode2 == OP_SMALLDATA)
+            {
+                // small pushdata, <= 80 bytes
+                if (vch1.size() > 80)
+                    break;
+            }
             else if (opcode1 != opcode2 || vch1 != vch2)
             {
                 // Others must match exactly
@@ -1294,6 +1305,7 @@ bool Solver(const CKeyStore& keystore, const CScript& scriptPubKey, uint256 hash
     switch (whichTypeRet)
     {
     case TX_NONSTANDARD:
+    case TX_NULL_DATA:
         return false;
     case TX_PUBKEY:
         keyID = CPubKey(vSolutions[0]).GetID();
@@ -1325,6 +1337,8 @@ int ScriptSigArgsExpected(txnouttype t, const std::vector<std::vector<unsigned c
     {
     case TX_NONSTANDARD:
         return -1;
+    case TX_NULL_DATA:
+        return 1;
     case TX_PUBKEY:
         return 1;
     case TX_PUBKEYHASH:
@@ -1339,10 +1353,9 @@ int ScriptSigArgsExpected(txnouttype t, const std::vector<std::vector<unsigned c
     return -1;
 }
 
-bool IsStandard(const CScript& scriptPubKey)
+bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType)
 {
     vector<valtype> vSolutions;
-    txnouttype whichType;
     if (!Solver(scriptPubKey, whichType, vSolutions))
         return false;
 
@@ -1401,6 +1414,7 @@ bool IsMine(const CKeyStore &keystore, const CScript& scriptPubKey)
     switch (whichType)
     {
     case TX_NONSTANDARD:
+    case TX_NULL_DATA:
         return false;
     case TX_PUBKEY:
         keyID = CPubKey(vSolutions[0]).GetID();
@@ -1462,6 +1476,8 @@ bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, vecto
     vector<valtype> vSolutions;
     if (!Solver(scriptPubKey, typeRet, vSolutions))
         return false;
+    if (typeRet == TX_NULL_DATA)
+        return true;
 
     if (typeRet == TX_MULTISIG)
     {
@@ -1677,6 +1693,7 @@ static CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo,
     switch (txType)
     {
     case TX_NONSTANDARD:
+    case TX_NULL_DATA:
         // Don't know anything about this, assume bigger one is correct:
         if (sigs1.size() >= sigs2.size())
             return PushAll(sigs1);

src/script.h

@@ -46,6 +46,7 @@ enum txnouttype
     TX_PUBKEYHASH,
     TX_SCRIPTHASH,
     TX_MULTISIG,
+    TX_NULL_DATA,
 };
 
 class CNoDestination {
@@ -202,6 +203,7 @@ enum opcodetype
 
 
     // template matching params
+    OP_SMALLDATA = 0xf9,
     OP_SMALLINTEGER = 0xfa,
     OP_PUBKEYS = 0xfb,
     OP_PUBKEYHASH = 0xfd,
@@ -683,7 +685,7 @@ bool IsCanonicalSignature(const std::vector<unsigned char> &vchSig, unsigned int
 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags, int nHashType);
 bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::vector<unsigned char> >& vSolutionsRet);
 int ScriptSigArgsExpected(txnouttype t, const std::vector<std::vector<unsigned char> >& vSolutions);
-bool IsStandard(const CScript& scriptPubKey);
+bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType);
 bool IsMine(const CKeyStore& keystore, const CScript& scriptPubKey);
 bool IsMine(const CKeyStore& keystore, const CTxDestination &dest);
 void ExtractAffectedKeys(const CKeyStore &keystore, const CScript& scriptPubKey, std::vector<CKeyID> &vKeys);

src/test/multisig_tests.cpp

@@ -133,21 +133,23 @@ BOOST_AUTO_TEST_CASE(multisig_IsStandard)
     for (int i = 0; i < 4; i++)
         key[i].MakeNewKey(true);
 
+    txnouttype whichType;
+
     CScript a_and_b;
     a_and_b << OP_2 << key[0].GetPubKey() << key[1].GetPubKey() << OP_2 << OP_CHECKMULTISIG;
-    BOOST_CHECK(::IsStandard(a_and_b));
+    BOOST_CHECK(::IsStandard(a_and_b, whichType));
 
     CScript a_or_b;
     a_or_b  << OP_1 << key[0].GetPubKey() << key[1].GetPubKey() << OP_2 << OP_CHECKMULTISIG;
-    BOOST_CHECK(::IsStandard(a_or_b));
+    BOOST_CHECK(::IsStandard(a_or_b, whichType));
 
     CScript escrow;
     escrow << OP_2 << key[0].GetPubKey() << key[1].GetPubKey() << key[2].GetPubKey() << OP_3 << OP_CHECKMULTISIG;
-    BOOST_CHECK(::IsStandard(escrow));
+    BOOST_CHECK(::IsStandard(escrow, whichType));
 
     CScript one_of_four;
     one_of_four << OP_1 << key[0].GetPubKey() << key[1].GetPubKey() << key[2].GetPubKey() << key[3].GetPubKey() << OP_4 << OP_CHECKMULTISIG;
-    BOOST_CHECK(!::IsStandard(one_of_four));
+    BOOST_CHECK(!::IsStandard(one_of_four, whichType));
 
     CScript malformed[6];
     malformed[0] << OP_3 << key[0].GetPubKey() << key[1].GetPubKey() << OP_2 << OP_CHECKMULTISIG;
@@ -158,7 +160,7 @@ BOOST_AUTO_TEST_CASE(multisig_IsStandard)
     malformed[5] << OP_1 << key[0].GetPubKey() << key[1].GetPubKey();
 
     for (int i = 0; i < 6; i++)
-        BOOST_CHECK(!::IsStandard(malformed[i]));
+        BOOST_CHECK(!::IsStandard(malformed[i], whichType));
 }
 
 BOOST_AUTO_TEST_CASE(multisig_Solver1)

src/test/transaction_tests.cpp

@@ -273,6 +273,20 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
 
     t.vout[0].scriptPubKey = CScript() << OP_1;
     BOOST_CHECK(!IsStandardTx(t, reason));
+
+    // 80-byte TX_NULL_DATA (standard)
+    t.vout[0].scriptPubKey = CScript() << OP_RETURN << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef3804678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38");
+    BOOST_CHECK(IsStandardTx(t, reason));
+
+    // 81-byte TX_NULL_DATA (non-standard)
+    t.vout[0].scriptPubKey = CScript() << OP_RETURN << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef3804678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef3800");
+    BOOST_CHECK(!IsStandardTx(t, reason));
+
+    // Only one TX_NULL_DATA permitted
+    t.vout.resize(2);
+    t.vout[0].scriptPubKey = CScript() << OP_RETURN << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef3804678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38");
+    t.vout[1].scriptPubKey = CScript() << OP_RETURN << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef3804678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38");
+    BOOST_CHECK(!IsStandardTx(t, reason));
 }
 
 BOOST_AUTO_TEST_SUITE_END()