Sv2NewTemplate: add coinbase_witness

src/sv2/messages.cpp

@@ -12,6 +12,13 @@ node::Sv2NewTemplateMsg::Sv2NewTemplateMsg(const CBlockHeader& header, const CTr
 
     m_coinbase_tx_version = coinbase_tx->CURRENT_VERSION;
     m_coinbase_prefix = coinbase_tx->vin[0].scriptSig;
+    if (coinbase_tx->HasWitness()) {
+        const auto& witness_stack{coinbase_tx->vin[0].scriptWitness.stack};
+        Assert(witness_stack.size() == 1 || witness_stack[0].size() == 32);
+        m_coinbase_witness = uint256(witness_stack[0]);
+    } else {
+        m_coinbase_witness = uint256(0);
+    }
     m_coinbase_tx_input_sequence = coinbase_tx->vin[0].nSequence;
 
     // The coinbase nValue already contains the nFee + the Block Subsidy when built using CreateBlock().

src/sv2/messages.h

@@ -282,6 +282,18 @@ struct Sv2NewTemplateMsg
      */
     CScript m_coinbase_prefix;
 
+    /**
+     * 32 byte array of the first (and only) witness stack element of the coinbase.
+     *
+     * If there is no segwit commitment in m_coinbase_tx_outputs this value
+     * must be ignored.
+     *
+     * This is the BIP 141 witness reserved value. A future soft fork may move
+     * the witness reserved value elsewhere. In that case this field still
+     * represents the coinbase witness, for backward compatibility.
+     */
+    uint256 m_coinbase_witness;
+
     /**
      * The coinbase transaction input’s nSequence field.
      */
@@ -324,6 +336,7 @@ struct Sv2NewTemplateMsg
           << m_version
           << m_coinbase_tx_version
           << m_coinbase_prefix
+          << m_coinbase_witness
           << m_coinbase_tx_input_sequence
           << m_coinbase_tx_value_remaining
           << m_coinbase_tx_outputs_count;

src/test/sv2_messages_tests.cpp

@@ -110,6 +110,7 @@ BOOST_AUTO_TEST_CASE(Sv2NewTemplate_test)
     // U32              02000000            coinbase tx version
     // B0_255           04                  coinbase_prefix len
     //                  03012100            coinbase prefix
+    // U256             0000000000000000000000000000000000000000000000000000000000000000 - witness
     // U32              ffffffff            coinbase tx input sequence
     // U64              0040075af0750700    coinbase tx value remaining
     // U32              01000000            coinbase tx outputs count
@@ -119,7 +120,7 @@ BOOST_AUTO_TEST_CASE(Sv2NewTemplate_test)
     // U32              dbc80d00            coinbase lock time (height 903,387)
     // SEQ0_255[U256]   01                  merkle path length
     //                  1a6240823de4c8d6aaf826851bdf2b0e8d5acf7c31e8578cff4c394b5a32bd4e - merkle path
-    std::string expected{"01000000000000000000000030020000000403012100ffffffff0040075af0750700010000000c000100000000000000036a012adbc80d00011a6240823de4c8d6aaf826851bdf2b0e8d5acf7c31e8578cff4c394b5a32bd4e"};
+    std::string expected{"010000000000000000000000300200000004030121000000000000000000000000000000000000000000000000000000000000000000ffffffff0040075af0750700010000000c000100000000000000036a012adbc80d00011a6240823de4c8d6aaf826851bdf2b0e8d5acf7c31e8578cff4c394b5a32bd4e"};
 
     node::Sv2NewTemplateMsg new_template;
     new_template.m_template_id = 1;
@@ -131,6 +132,8 @@ BOOST_AUTO_TEST_CASE(Sv2NewTemplate_test)
     CScript prefix(coinbase_prefix.begin(), coinbase_prefix.end());
     new_template.m_coinbase_prefix = prefix;
 
+    new_template.m_coinbase_witness = uint256(0);
+
     new_template.m_coinbase_tx_input_sequence = 4294967295;
     new_template.m_coinbase_tx_value_remaining = MAX_MONEY;
 

src/test/sv2_template_provider_tests.cpp

@@ -61,7 +61,8 @@ BOOST_AUTO_TEST_CASE(client_tests)
         1 +                 // future_template
         4 +                 // version
         4 +                 // coinbase_tx_version
-    2 +                 // coinbase_prefix (CompactSize(1) + 1-byte OP_0)
+        2 +                 // coinbase_prefix (CompactSize(1) + 1-byte OP_0)
+        32 +                // coinbase_witness (fixed-size reserved value)
         4 +                 // coinbase_tx_input_sequence
         8 +                 // coinbase_tx_value_remaining
         4 +                 // coinbase_tx_outputs_count (0)