Merge bitcoin#17004: validation: Remove REJECT code from CValidationState

9075d13 [docs] Add release notes for removal of REJECT reasons (John Newbery)
04a2f32 [validation] Fix REJECT message comments (John Newbery)
e9d5a59 [validation] Remove REJECT code from CValidationState (John Newbery)
0053e16 [logging] Don't log REJECT code when transaction is rejected (John Newbery)
a1a07cf [validation] Fix peer punishment for bad blocks (John Newbery)

Pull request description:

  We no longer send BIP 61 REJECT messages, so there's no need to set
  a REJECT code in the CValidationState object.

  Note that there is a minor bug fix in p2p behaviour here. Because the
  call to `MaybePunishNode()` in `PeerLogicValidation::BlockChecked()` only
  previously happened if the REJECT code was > 0 and < `REJECT_INTERNAL`,
  then there are cases were `MaybePunishNode()` can get called where it
  wasn't previously:

  - when `AcceptBlockHeader()` fails with `CACHED_INVALID`.
  - when `AcceptBlockHeader()` fails with `BLOCK_MISSING_PREV`.

  Note that `BlockChecked()` cannot fail with an 'internal' reject code. The
  only internal reject code was `REJECT_HIGHFEE`, which was only set in
  ATMP.

  This reverts a minor bug introduced in 5d08c9c.

ACKs for top commit:
  ariard:
    ACK 9075d13, changes since last reviewed are splitting them in separate commits to ease understanding and fix nits
  fjahr:
    ACK 9075d13, confirmed diff to last review was fixing nits in docs/comments.
  ryanofsky:
    Code review ACK 9075d13. Only changes since last review are splitting the main commit and updating comments

Tree-SHA512: 58e8a1a4d4e6f156da5d29fb6ad6a62fc9c594bbfc6432b3252e962d0e9e10149bf3035185dc5320c46c09f3e49662bc2973ec759679c0f3412232087cb8a3a7

Author: laanwj

doc/release-notes-15437.md

@@ -32,3 +32,22 @@ Please use the recommended alternatives if you rely on this deprecated feature:
   could wait until the transaction has confirmed (taking into account the fee
   target they set (compare the RPC `estimatesmartfee`)) or listen for the
   transaction announcement by other network peers to check for propagation.
+
+The removal of BIP61 REJECT message support also has the following minor RPC
+and logging implications:
+
+* `testmempoolaccept` and `sendrawtransaction` no longer return the P2P REJECT
+  code when a transaction is not accepted to the mempool. They still return the
+  verbal reject reason.
+
+* Log messages that previously reported the REJECT code when a transaction was
+  not accepted to the mempool now no longer report the REJECT code. The reason
+  for rejection is still reported.
+
+Updated RPCs
+------------
+
+- `testmempoolaccept` and `sendrawtransaction` no longer return the P2P REJECT
+  code when a transaction is not accepted to the mempool. See the Section
+  _Removal of reject network messages from Bitcoin Core (BIP61)_ for details on
+  the removal of BIP61 REJECT message support.

src/consensus/tx_check.cpp

@@ -11,24 +11,24 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fChe
 {
     // Basic checks that don't depend on any context
     if (tx.vin.empty())
-        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vin-empty");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-vin-empty");
     if (tx.vout.empty())
-        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vout-empty");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-vout-empty");
     // Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)
     if (::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * WITNESS_SCALE_FACTOR > MAX_BLOCK_WEIGHT)
-        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-oversize");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-oversize");
 
     // Check for negative or overflow output values (see CVE-2010-5139)
     CAmount nValueOut = 0;
     for (const auto& txout : tx.vout)
     {
         if (txout.nValue < 0)
-            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vout-negative");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-vout-negative");
         if (txout.nValue > MAX_MONEY)
-            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vout-toolarge");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-vout-toolarge");
         nValueOut += txout.nValue;
         if (!MoneyRange(nValueOut))
-            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-txouttotal-toolarge");
     }
 
     // Check for duplicate inputs - note that this check is slow so we skip it in CheckBlock
@@ -37,20 +37,20 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fChe
         for (const auto& txin : tx.vin)
         {
             if (!vInOutPoints.insert(txin.prevout).second)
-                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-inputs-duplicate");
         }
     }
 
     if (tx.IsCoinBase())
     {
         if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
-            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-cb-length");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-cb-length");
     }
     else
     {
         for (const auto& txin : tx.vin)
             if (txin.prevout.IsNull())
-                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-prevout-null");
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-prevout-null");
     }
 
     return true;

src/consensus/tx_verify.cpp

@@ -160,7 +160,7 @@ bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, c
 {
     // are the actual inputs available?
     if (!inputs.HaveInputs(tx)) {
-        return state.Invalid(ValidationInvalidReason::TX_MISSING_INPUTS, false, REJECT_INVALID, "bad-txns-inputs-missingorspent",
+        return state.Invalid(ValidationInvalidReason::TX_MISSING_INPUTS, false, "bad-txns-inputs-missingorspent",
                          strprintf("%s: inputs missing/spent", __func__));
     }
 
@@ -172,27 +172,27 @@ bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, c
 
         // If prev is coinbase, check that it's matured
         if (coin.IsCoinBase() && nSpendHeight - coin.nHeight < COINBASE_MATURITY) {
-            return state.Invalid(ValidationInvalidReason::TX_PREMATURE_SPEND, false, REJECT_INVALID, "bad-txns-premature-spend-of-coinbase",
+            return state.Invalid(ValidationInvalidReason::TX_PREMATURE_SPEND, false, "bad-txns-premature-spend-of-coinbase",
                 strprintf("tried to spend coinbase at depth %d", nSpendHeight - coin.nHeight));
         }
 
         // Check for negative or overflow input values
         nValueIn += coin.out.nValue;
         if (!MoneyRange(coin.out.nValue) || !MoneyRange(nValueIn)) {
-            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-inputvalues-outofrange");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-inputvalues-outofrange");
         }
     }
 
     const CAmount value_out = tx.GetValueOut();
     if (nValueIn < value_out) {
-        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-in-belowout",
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-in-belowout",
             strprintf("value in (%s) < value out (%s)", FormatMoney(nValueIn), FormatMoney(value_out)));
     }
 
     // Tally transaction fees
     const CAmount txfee_aux = nValueIn - value_out;
     if (!MoneyRange(txfee_aux)) {
-        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-fee-outofrange");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, "bad-txns-fee-outofrange");
     }
 
     txfee = txfee_aux;

src/consensus/validation.h

@@ -12,20 +12,8 @@
 #include <primitives/transaction.h>
 #include <primitives/block.h>
 
-/** "reject" message codes */
-static const unsigned char REJECT_MALFORMED = 0x01;
-static const unsigned char REJECT_INVALID = 0x10;
-static const unsigned char REJECT_OBSOLETE = 0x11;
-static const unsigned char REJECT_DUPLICATE = 0x12;
-static const unsigned char REJECT_NONSTANDARD = 0x40;
-// static const unsigned char REJECT_DUST = 0x41; // part of BIP 61
-static const unsigned char REJECT_INSUFFICIENTFEE = 0x42;
-static const unsigned char REJECT_CHECKPOINT = 0x43;
-
 /** A "reason" why something was invalid, suitable for determining whether the
   * provider of the object should be banned/ignored/disconnected/etc.
-  * These are much more granular than the rejection codes, which may be more
-  * useful for some other use-cases.
   */
 enum class ValidationInvalidReason {
     // txn and blocks:
@@ -104,15 +92,13 @@ class CValidationState {
     } mode;
     ValidationInvalidReason m_reason;
     std::string strRejectReason;
-    unsigned int chRejectCode;
     std::string strDebugMessage;
 public:
-    CValidationState() : mode(MODE_VALID), m_reason(ValidationInvalidReason::NONE), chRejectCode(0) {}
+    CValidationState() : mode(MODE_VALID), m_reason(ValidationInvalidReason::NONE) {}
     bool Invalid(ValidationInvalidReason reasonIn, bool ret = false,
-            unsigned int chRejectCodeIn=0, const std::string &strRejectReasonIn="",
+            const std::string &strRejectReasonIn="",
             const std::string &strDebugMessageIn="") {
         m_reason = reasonIn;
-        chRejectCode = chRejectCodeIn;
         strRejectReason = strRejectReasonIn;
         strDebugMessage = strDebugMessageIn;
         if (mode == MODE_ERROR)
@@ -136,7 +122,6 @@ class CValidationState {
         return mode == MODE_ERROR;
     }
     ValidationInvalidReason GetReason() const { return m_reason; }
-    unsigned int GetRejectCode() const { return chRejectCode; }
     std::string GetRejectReason() const { return strRejectReason; }
     std::string GetDebugMessage() const { return strDebugMessage; }
 };

src/net_processing.cpp

@@ -116,8 +116,8 @@ namespace {
     int nSyncStarted GUARDED_BY(cs_main) = 0;
 
     /**
-     * Sources of received blocks, saved to be able to send them reject
-     * messages or ban them when processing happens afterwards.
+     * Sources of received blocks, saved to be able punish them when processing
+     * happens afterwards.
      * Set mapBlockSource[hash].second to false if the node should not be
      * punished if the block is invalid.
      */
@@ -1233,11 +1233,12 @@ void PeerLogicValidation::BlockChecked(const CBlock& block, const CValidationSta
     const uint256 hash(block.GetHash());
     std::map<uint256, std::pair<NodeId, bool>>::iterator it = mapBlockSource.find(hash);
 
-    if (state.IsInvalid()) {
-        // Don't send reject message with code 0 or an internal reject code.
-        if (it != mapBlockSource.end() && State(it->second.first) && state.GetRejectCode() > 0 && state.GetRejectCode() < REJECT_INTERNAL) {
+    // If the block failed validation, we know where it came from and we're still connected
+    // to that peer, maybe punish.
+    if (state.IsInvalid() &&
+        it != mapBlockSource.end() &&
+        State(it->second.first)) {
             MaybePunishNode(/*nodeid=*/ it->second.first, state, /*via_compact_block=*/ !it->second.second);
-        }
     }
     // Check that:
     // 1. The block is valid
@@ -2859,11 +2860,12 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 // been run).  This is handled below, so just treat this as
                 // though the block was successfully read, and rely on the
                 // handling in ProcessNewBlock to ensure the block index is
-                // updated, reject messages go out, etc.
+                // updated, etc.
                 MarkBlockAsReceived(resp.blockhash); // it is now an empty pointer
                 fBlockRead = true;
-                // mapBlockSource is only used for sending reject messages and DoS scores,
-                // so the race between here and cs_main in ProcessNewBlock is fine.
+                // mapBlockSource is used for potentially punishing peers and
+                // updating which peers send us compact blocks, so the race
+                // between here and cs_main in ProcessNewBlock is fine.
                 // BIP 152 permits peers to relay compact blocks after validating
                 // the header only; we should not punish peers if the block turns
                 // out to be invalid.
@@ -2935,8 +2937,9 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             // Also always process if we requested the block explicitly, as we may
             // need it even though it is not a candidate for a new best tip.
             forceProcessing |= MarkBlockAsReceived(hash);
-            // mapBlockSource is only used for sending reject messages and DoS scores,
-            // so the race between here and cs_main in ProcessNewBlock is fine.
+            // mapBlockSource is only used for punishing peers and setting
+            // which peers send us compact blocks, so the race between here and
+            // cs_main in ProcessNewBlock is fine.
             mapBlockSource.emplace(hash, std::make_pair(pfrom->GetId(), true));
         }
         bool fNewBlock = false;

src/rpc/rawtransaction.cpp

@@ -904,7 +904,7 @@ static UniValue testmempoolaccept(const JSONRPCRequest& request)
     result_0.pushKV("allowed", test_accept_res);
     if (!test_accept_res) {
         if (state.IsInvalid()) {
-            result_0.pushKV("reject-reason", strprintf("%i: %s", state.GetRejectCode(), state.GetRejectReason()));
+            result_0.pushKV("reject-reason", strprintf("%s", state.GetRejectReason()));
         } else if (missing_inputs) {
             result_0.pushKV("reject-reason", "missing-inputs");
         } else {

src/util/validation.cpp

@@ -11,10 +11,9 @@
 /** Convert CValidationState to a human-readable message for logging */
 std::string FormatStateMessage(const CValidationState &state)
 {
-    return strprintf("%s%s (code %i)",
+    return strprintf("%s%s",
         state.GetRejectReason(),
-        state.GetDebugMessage().empty() ? "" : ", "+state.GetDebugMessage(),
-        state.GetRejectCode());
+        state.GetDebugMessage().empty() ? "" : ", "+state.GetDebugMessage());
 }
 
 const std::string strMessageMagic = "Bitcoin Signed Message:\n";