Merge #15141: Rewrite DoS interface between validation and net_processing

0ff1c2a838da9e8dc7f77609adc89124bbea3e2b Separate reason for premature spends (coinbase/locktime) (Suhas Daftuar)
54470e767bab37f9b7089782b1be73d5883bb244 Assert validation reasons are contextually correct (Suhas Daftuar)
2120c31521aa51aa1984ee33250b8320506d3a0f [refactor] Update some comments in validation.cpp as we arent doing DoS there (Matt Corallo)
12dbdd7a41bac73e51ed8f7b290b7671196bf9ea [refactor] Drop unused state.DoS(), state.GetDoS(), state.CorruptionPossible() (Matt Corallo)
aa502b88d10c2c3ac56d9163555849b96dc4df1e scripted-diff: Remove DoS calls to CValidationState (Matt Corallo)
7721ad64f40a0c67edefaaf7353264d78df8803e [refactor] Prep for scripted-diff by removing some \ns which annoy sed. (Matt Corallo)
5e78c5734bb0c9aae7b0a7019a745b2d7059b3d9 Allow use of state.Invalid() for all reasons (Matt Corallo)
6b34bc6b6f54f85537494cbea3846d5d195a06d9 Fix handling of invalid headers (Suhas Daftuar)
ef54b486d5333dfc85c56e6b933c81735196a25d [refactor] Use Reasons directly instead of DoS codes (Matt Corallo)
9ab2a0412e96e87956fe61257387683635213035 CorruptionPossible -> BLOCK_MUTATED (Matt Corallo)
6e55b292b0ea944897b6dc2f766446fd209af484 CorruptionPossible -> TX_WITNESS_MUTATED (Matt Corallo)
7df16e70e67c753c871797ce947ea09d7cb0e519 LookupBlockIndex -> CACHED_INVALID (Matt Corallo)
c8b0d22698385f91215ce8145631e3d5826dc977 [refactor] Drop redundant nDoS, corruptionPossible, SetCorruptionPossible (Matt Corallo)
34477ccd39a8d4bfa8ad612f22d5a46291922185 [refactor] Add useful-for-dos "reason" field to CValidationState (Matt Corallo)
6a7f8777a0b193fae4f976196f3464ffac01bf1b Ban all peers for all block script failures (Suhas Daftuar)
7b999103e21509e1c2dec10f68e48744ffe90f55 Clean up banning levels (Matt Corallo)
b8b4c80146780f9011abbd1be72343cc965c07b9 [refactor] drop IsInvalid(nDoSOut) (Matt Corallo)
8818729013e17c650a25f030b2b80e0997389155 [refactor] Refactor misbehavior ban decisions to MaybePunishNode() (Matt Corallo)
00e11e61c0211a62788611cd6a6714a393fdc26c [refactor] rename stateDummy -> orphan_state (Matt Corallo)
f34fa719cf33a51d11f1d2219cbe73ccff6fd697 Drop obsolete sigops comment (Matt Corallo)

Pull request description:

  This is a rebase of #11639 with some fixes for the last few comments which were not yet addressed.

  The original PR text, with some strikethroughs of text that is no longer correct:

  > This cleans up an old main-carryover - it made sense that main could decide what DoS scores to assign things because the DoS scores were handled in a different part of main, but now validation is telling net_processing what DoS scores to assign to different things, which is utter nonsense. Instead, we replace CValidationState's nDoS and CorruptionPossible with a general ValidationInvalidReason, which net_processing can handle as it sees fit. I keep the behavior changes here to a minimum, but in the future we can utilize these changes for other smarter behavior, such as disconnecting/preferring to rotate outbound peers based on them providing things which are invalid due to SOFT_FORK because we shouldn't ban for such cases.
  >
  > This is somewhat complementary with, though obviously conflicts heavily with #11523, which added enums in place of DoS scores, as well as a few other cleanups (which are still relevant).
  >
  > Compared with previous bans, the following changes are made:
  >
  > Txn with empty vin/vout or null prevouts move from 10 DoS
  > points to 100.
  > Loose transactions with a dependency loop now result in a ban
  > instead of 10 DoS points.
  > ~~BIP68-violation no longer results in a ban as it is SOFT_FORK.~~
  > ~~Non-SegWit SigOp violation no longer results in a ban as it
  > considers P2SH sigops and is thus SOFT_FORK.~~
  > ~~Any script violation in a block no longer results in a ban as
  > it may be the result of a SOFT_FORK. This should likely be
  > fixed in the future by differentiating between them.~~
  > Proof of work failure moves from 50 DoS points to a ban.
  > Blocks with timestamps under MTP now result in a ban, blocks
  > too far in the future continue to not result in a ban.
  > Inclusion of non-final transactions in a block now results in a
  > ban instead of 10 DoS points.

  Note: The change to ban all peers for consensus violations is actually NOT the change I'd like to make -- I'd prefer to only ban outbound peers in those situations.  The current behavior is a bit of a mess, however, and so in the interests of advancing this PR I tried to keep the changes to a minimum.  I plan to revisit the behavior in a followup PR.

  EDIT: One reviewer suggested I add some additional context for this PR:

  > The goal of this work was to make net_processing aware of the actual reasons for validation failures, rather than just deal with opaque numbers instructing it to do something.
  >
  > In the future, I'd like to make it so that we use more context to decide how to punish a peer. One example is to differentiate inbound and outbound peer misbehaviors. Another potential example is if we'd treat RECENT_CONSENSUS_CHANGE failures differently (ie after the next consensus change is implemented), and perhaps again we'd want to treat some peers differently than others.

ACKs for commit 0ff1c2:
  jnewbery:
    utACK 0ff1c2a838da9e8dc7f77609adc89124bbea3e2b
  ryanofsky:
    utACK 0ff1c2a838da9e8dc7f77609adc89124bbea3e2b. Only change is dropping the first commit (f3883a321bf4ab289edcd9754b12cae3a648b175), and dropping the temporary `assert(level == GetDoS())` that was in 35ee77f2832eaffce30042e00785c310c5540cdc (now c8b0d22698385f91215ce8145631e3d5826dc977)

Tree-SHA512: e915a411100876398af5463d0a885920e44d473467bb6af991ef2e8f2681db6c1209bb60f848bd154be72d460f039b5653df20a6840352c5f7ea5486d9f777a3

7 files changed, 317 insertions, 214 deletions

diff --git a/src/blockencodings.cpp b/src/blockencodings.cpp
index 10f51931f0..f0fcf675eb 100644
--- a/src/blockencodings.cpp
+++ b/src/blockencodings.cpp
@@ -203,7 +203,7 @@ ReadStatus PartiallyDownloadedBlock::FillBlock(CBlock& block, const std::vector<
         // but that is expensive, and CheckBlock caches a block's
         // "checked-status" (in the CBlock?). CBlock should be able to
         // check its own merkle root and cache that check.
-        if (state.CorruptionPossible())
+        if (state.GetReason() == ValidationInvalidReason::BLOCK_MUTATED)
             return READ_STATUS_FAILED; // Possible Short ID collision
         return READ_STATUS_CHECKBLOCK_FAILED;
     }
diff --git a/src/consensus/tx_check.cpp b/src/consensus/tx_check.cpp
index 61a607ef7f..23ed3ecb53 100644
--- a/src/consensus/tx_check.cpp
+++ b/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.DoS(10, false, REJECT_INVALID, "bad-txns-vin-empty");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vin-empty");
     if (tx.vout.empty())
-        return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "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.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-oversize");
 
     // Check for negative or overflow output values
     CAmount nValueOut = 0;
     for (const auto& txout : tx.vout)
     {
         if (txout.nValue < 0)
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-negative");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vout-negative");
         if (txout.nValue > MAX_MONEY)
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-toolarge");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-vout-toolarge");
         nValueOut += txout.nValue;
         if (!MoneyRange(nValueOut))
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "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.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
         }
     }
 
     if (tx.IsCoinBase())
     {
         if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
-            return state.DoS(100, false, REJECT_INVALID, "bad-cb-length");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-cb-length");
     }
     else
     {
         for (const auto& txin : tx.vin)
             if (txin.prevout.IsNull())
-                return state.DoS(10, false, REJECT_INVALID, "bad-txns-prevout-null");
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-prevout-null");
     }
 
     return true;
diff --git a/src/consensus/tx_verify.cpp b/src/consensus/tx_verify.cpp
index fbbbcfd040..4b93cae848 100644
--- a/src/consensus/tx_verify.cpp
+++ b/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.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-missingorspent", false,
+        return state.Invalid(ValidationInvalidReason::TX_MISSING_INPUTS, false, REJECT_INVALID, "bad-txns-inputs-missingorspent",
                          strprintf("%s: inputs missing/spent", __func__));
     }
 
@@ -172,28 +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(false,
-                REJECT_INVALID, "bad-txns-premature-spend-of-coinbase",
+            return state.Invalid(ValidationInvalidReason::TX_PREMATURE_SPEND, false, REJECT_INVALID, "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.DoS(100, false, REJECT_INVALID, "bad-txns-inputvalues-outofrange");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-inputvalues-outofrange");
         }
     }
 
     const CAmount value_out = tx.GetValueOut();
     if (nValueIn < value_out) {
-        return state.DoS(100, false, REJECT_INVALID, "bad-txns-in-belowout", false,
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "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.DoS(100, false, REJECT_INVALID, "bad-txns-fee-outofrange");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-fee-outofrange");
     }
 
     txfee = txfee_aux;
diff --git a/src/consensus/validation.h b/src/consensus/validation.h
index f2e2c3585a..2e23f4b3a4 100644
--- a/src/consensus/validation.h
+++ b/src/consensus/validation.h
@@ -22,6 +22,78 @@ static const unsigned char REJECT_NONSTANDARD = 0x40;
 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:
+    NONE,                    //!< not actually invalid
+    CONSENSUS,               //!< invalid by consensus rules (excluding any below reasons)
+    /**
+     * Invalid by a change to consensus rules more recent than SegWit.
+     * Currently unused as there are no such consensus rule changes, and any download
+     * sources realistically need to support SegWit in order to provide useful data,
+     * so differentiating between always-invalid and invalid-by-pre-SegWit-soft-fork
+     * is uninteresting.
+     */
+    RECENT_CONSENSUS_CHANGE,
+    // Only blocks (or headers):
+    CACHED_INVALID,          //!< this object was cached as being invalid, but we don't know why
+    BLOCK_INVALID_HEADER,    //!< invalid proof of work or time too old
+    BLOCK_MUTATED,           //!< the block's data didn't match the data committed to by the PoW
+    BLOCK_MISSING_PREV,      //!< We don't have the previous block the checked one is built on
+    BLOCK_INVALID_PREV,      //!< A block this one builds on is invalid
+    BLOCK_TIME_FUTURE,          //!< block timestamp was > 2 hours in the future (or our clock is bad)
+    BLOCK_CHECKPOINT,        //!< the block failed to meet one of our checkpoints
+    // Only loose txn:
+    TX_NOT_STANDARD,          //!< didn't meet our local policy rules
+    TX_MISSING_INPUTS,        //!< a transaction was missing some of its inputs
+    TX_PREMATURE_SPEND,       //!< transaction spends a coinbase too early, or violates locktime/sequence locks
+    /**
+     * Transaction might be missing a witness, have a witness prior to SegWit
+     * activation, or witness may have been malleated (which includes
+     * non-standard witnesses).
+     */
+    TX_WITNESS_MUTATED,
+    /**
+     * Tx already in mempool or conflicts with a tx in the chain
+     * (if it conflicts with another tx in mempool, we use MEMPOOL_POLICY as it failed to reach the RBF threshold)
+     * TODO: Currently this is only used if the transaction already exists in the mempool or on chain,
+     * TODO: ATMP's fMissingInputs and a valid CValidationState being used to indicate missing inputs
+     */
+    TX_CONFLICT,
+    TX_MEMPOOL_POLICY,        //!< violated mempool's fee/size/descendant/RBF/etc limits
+};
+
+inline bool IsTransactionReason(ValidationInvalidReason r)
+{
+    return r == ValidationInvalidReason::NONE ||
+           r == ValidationInvalidReason::CONSENSUS ||
+           r == ValidationInvalidReason::RECENT_CONSENSUS_CHANGE ||
+           r == ValidationInvalidReason::TX_NOT_STANDARD ||
+           r == ValidationInvalidReason::TX_PREMATURE_SPEND ||
+           r == ValidationInvalidReason::TX_MISSING_INPUTS ||
+           r == ValidationInvalidReason::TX_WITNESS_MUTATED ||
+           r == ValidationInvalidReason::TX_CONFLICT ||
+           r == ValidationInvalidReason::TX_MEMPOOL_POLICY;
+}
+
+inline bool IsBlockReason(ValidationInvalidReason r)
+{
+    return r == ValidationInvalidReason::NONE ||
+           r == ValidationInvalidReason::CONSENSUS ||
+           r == ValidationInvalidReason::RECENT_CONSENSUS_CHANGE ||
+           r == ValidationInvalidReason::CACHED_INVALID ||
+           r == ValidationInvalidReason::BLOCK_INVALID_HEADER ||
+           r == ValidationInvalidReason::BLOCK_MUTATED ||
+           r == ValidationInvalidReason::BLOCK_MISSING_PREV ||
+           r == ValidationInvalidReason::BLOCK_INVALID_PREV ||
+           r == ValidationInvalidReason::BLOCK_TIME_FUTURE ||
+           r == ValidationInvalidReason::BLOCK_CHECKPOINT;
+}
+
 /** Capture information about block/transaction validation */
 class CValidationState {
 private:
@@ -30,32 +102,24 @@ private:
         MODE_INVALID, //!< network rule violation (DoS value may be set)
         MODE_ERROR,   //!< run-time error
     } mode;
-    int nDoS;
+    ValidationInvalidReason m_reason;
     std::string strRejectReason;
     unsigned int chRejectCode;
-    bool corruptionPossible;
     std::string strDebugMessage;
 public:
-    CValidationState() : mode(MODE_VALID), nDoS(0), chRejectCode(0), corruptionPossible(false) {}
-    bool DoS(int level, bool ret = false,
-             unsigned int chRejectCodeIn=0, const std::string &strRejectReasonIn="",
-             bool corruptionIn=false,
-             const std::string &strDebugMessageIn="") {
+    CValidationState() : mode(MODE_VALID), m_reason(ValidationInvalidReason::NONE), chRejectCode(0) {}
+    bool Invalid(ValidationInvalidReason reasonIn, bool ret = false,
+            unsigned int chRejectCodeIn=0, const std::string &strRejectReasonIn="",
+            const std::string &strDebugMessageIn="") {
+        m_reason = reasonIn;
         chRejectCode = chRejectCodeIn;
         strRejectReason = strRejectReasonIn;
-        corruptionPossible = corruptionIn;
         strDebugMessage = strDebugMessageIn;
         if (mode == MODE_ERROR)
             return ret;
-        nDoS += level;
         mode = MODE_INVALID;
         return ret;
     }
-    bool Invalid(bool ret = false,
-                 unsigned int _chRejectCode=0, const std::string &_strRejectReason="",
-                 const std::string &_strDebugMessage="") {
-        return DoS(0, ret, _chRejectCode, _strRejectReason, false, _strDebugMessage);
-    }
     bool Error(const std::string& strRejectReasonIn) {
         if (mode == MODE_VALID)
             strRejectReason = strRejectReasonIn;
@@ -71,19 +135,7 @@ public:
     bool IsError() const {
         return mode == MODE_ERROR;
     }
-    bool IsInvalid(int &nDoSOut) const {
-        if (IsInvalid()) {
-            nDoSOut = nDoS;
-            return true;
-        }
-        return false;
-    }
-    bool CorruptionPossible() const {
-        return corruptionPossible;
-    }
-    void SetCorruptionPossible() {
-        corruptionPossible = true;
-    }
+    ValidationInvalidReason GetReason() const { return m_reason; }
     unsigned int GetRejectCode() const { return chRejectCode; }
     std::string GetRejectReason() const { return strRejectReason; }
     std::string GetDebugMessage() const { return strDebugMessage; }
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 74e33189dc..71ebd72b83 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -351,7 +351,16 @@ struct CNodeState {
 
     TxDownloadState m_tx_download;
 
-    CNodeState(CAddress addrIn, std::string addrNameIn) : address(addrIn), name(addrNameIn) {
+    //! Whether this peer is an inbound connection
+    bool m_is_inbound;
+
+    //! Whether this peer is a manual connection
+    bool m_is_manual_connection;
+
+    CNodeState(CAddress addrIn, std::string addrNameIn, bool is_inbound, bool is_manual) :
+        address(addrIn), name(std::move(addrNameIn)), m_is_inbound(is_inbound),
+        m_is_manual_connection (is_manual)
+    {
         fCurrentlyConnected = false;
         nMisbehavior = 0;
         fShouldBan = false;
@@ -747,7 +756,7 @@ void PeerLogicValidation::InitializeNode(CNode *pnode) {
     NodeId nodeid = pnode->GetId();
     {
         LOCK(cs_main);
-        mapNodeState.emplace_hint(mapNodeState.end(), std::piecewise_construct, std::forward_as_tuple(nodeid), std::forward_as_tuple(addr, std::move(addrName)));
+        mapNodeState.emplace_hint(mapNodeState.end(), std::piecewise_construct, std::forward_as_tuple(nodeid), std::forward_as_tuple(addr, std::move(addrName), pnode->fInbound, pnode->m_manual_connection));
     }
     if(!pnode->fInbound)
         PushNodeVersion(pnode, connman, GetTime());
@@ -959,6 +968,90 @@ void Misbehaving(NodeId pnode, int howmuch, const std::string& message) EXCLUSIV
         LogPrint(BCLog::NET, "%s: %s peer=%d (%d -> %d)%s\n", __func__, state->name, pnode, state->nMisbehavior-howmuch, state->nMisbehavior, message_prefixed);
 }
 
+/**
+ * Returns true if the given validation state result may result in a peer
+ * banning/disconnecting us. We use this to determine which unaccepted
+ * transactions from a whitelisted peer that we can safely relay.
+ */
+static bool TxRelayMayResultInDisconnect(const CValidationState& state)
+{
+    assert(IsTransactionReason(state.GetReason()));
+    return state.GetReason() == ValidationInvalidReason::CONSENSUS;
+}
+
+/**
+ * Potentially ban a node based on the contents of a CValidationState object
+ *
+ * @param[in] via_compact_block: this bool is passed in because net_processing should
+ * punish peers differently depending on whether the data was provided in a compact
+ * block message or not. If the compact block had a valid header, but contained invalid
+ * txs, the peer should not be punished. See BIP 152.
+ *
+ * @return Returns true if the peer was punished (probably disconnected)
+ *
+ * Changes here may need to be reflected in TxRelayMayResultInDisconnect().
+ */
+static bool MaybePunishNode(NodeId nodeid, const CValidationState& state, bool via_compact_block, const std::string& message = "") {
+    switch (state.GetReason()) {
+    case ValidationInvalidReason::NONE:
+        break;
+    // The node is providing invalid data:
+    case ValidationInvalidReason::CONSENSUS:
+    case ValidationInvalidReason::BLOCK_MUTATED:
+        if (!via_compact_block) {
+            LOCK(cs_main);
+            Misbehaving(nodeid, 100, message);
+            return true;
+        }
+        break;
+    case ValidationInvalidReason::CACHED_INVALID:
+        {
+            LOCK(cs_main);
+            CNodeState *node_state = State(nodeid);
+            if (node_state == nullptr) {
+                break;
+            }
+
+            // Ban outbound (but not inbound) peers if on an invalid chain.
+            // Exempt HB compact block peers and manual connections.
+            if (!via_compact_block && !node_state->m_is_inbound && !node_state->m_is_manual_connection) {
+                Misbehaving(nodeid, 100, message);
+                return true;
+            }
+            break;
+        }
+    case ValidationInvalidReason::BLOCK_INVALID_HEADER:
+    case ValidationInvalidReason::BLOCK_CHECKPOINT:
+    case ValidationInvalidReason::BLOCK_INVALID_PREV:
+        {
+            LOCK(cs_main);
+            Misbehaving(nodeid, 100, message);
+        }
+        return true;
+    // Conflicting (but not necessarily invalid) data or different policy:
+    case ValidationInvalidReason::BLOCK_MISSING_PREV:
+        {
+            // TODO: Handle this much more gracefully (10 DoS points is super arbitrary)
+            LOCK(cs_main);
+            Misbehaving(nodeid, 10, message);
+        }
+        return true;
+    case ValidationInvalidReason::RECENT_CONSENSUS_CHANGE:
+    case ValidationInvalidReason::BLOCK_TIME_FUTURE:
+    case ValidationInvalidReason::TX_NOT_STANDARD:
+    case ValidationInvalidReason::TX_MISSING_INPUTS:
+    case ValidationInvalidReason::TX_PREMATURE_SPEND:
+    case ValidationInvalidReason::TX_WITNESS_MUTATED:
+    case ValidationInvalidReason::TX_CONFLICT:
+    case ValidationInvalidReason::TX_MEMPOOL_POLICY:
+        break;
+    }
+    if (message != "") {
+        LogPrint(BCLog::NET, "peer=%d: %s\n", nodeid, message);
+    }
+    return false;
+}
+
 
 
 
@@ -1132,14 +1225,12 @@ 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);
 
-    int nDoS = 0;
-    if (state.IsInvalid(nDoS)) {
+    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) {
             CBlockReject reject = {(unsigned char)state.GetRejectCode(), state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), hash};
             State(it->second.first)->rejects.push_back(reject);
-            if (nDoS > 0 && it->second.second)
-                Misbehaving(it->second.first, nDoS);
+            MaybePunishNode(/*nodeid=*/ it->second.first, state, /*via_compact_block=*/ !it->second.second);
         }
     }
     // Check that:
@@ -1489,7 +1580,7 @@ inline void static SendBlockTransactions(const CBlock& block, const BlockTransac
     connman->PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCKTXN, resp));
 }
 
-bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams, bool punish_duplicate_invalid)
+bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams, bool via_compact_block)
 {
     const CNetMsgMaker msgMaker(pfrom->GetSendVersion());
     size_t nCount = headers.size();
@@ -1551,48 +1642,8 @@ bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::ve
     CValidationState state;
     CBlockHeader first_invalid_header;
     if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast, &first_invalid_header)) {
-        int nDoS;
-        if (state.IsInvalid(nDoS)) {
-            LOCK(cs_main);
-            if (nDoS > 0) {
-                Misbehaving(pfrom->GetId(), nDoS, "invalid header received");
-            } else {
-                LogPrint(BCLog::NET, "peer=%d: invalid header received\n", pfrom->GetId());
-            }
-            if (punish_duplicate_invalid && LookupBlockIndex(first_invalid_header.GetHash())) {
-                // Goal: don't allow outbound peers to use up our outbound
-                // connection slots if they are on incompatible chains.
-                //
-                // We ask the caller to set punish_invalid appropriately based
-                // on the peer and the method of header delivery (compact
-                // blocks are allowed to be invalid in some circumstances,
-                // under BIP 152).
-                // Here, we try to detect the narrow situation that we have a
-                // valid block header (ie it was valid at the time the header
-                // was received, and hence stored in mapBlockIndex) but know the
-                // block is invalid, and that a peer has announced that same
-                // block as being on its active chain.
-                // Disconnect the peer in such a situation.
-                //
-                // Note: if the header that is invalid was not accepted to our
-                // mapBlockIndex at all, that may also be grounds for
-                // disconnecting the peer, as the chain they are on is likely
-                // to be incompatible. However, there is a circumstance where
-                // that does not hold: if the header's timestamp is more than
-                // 2 hours ahead of our current time. In that case, the header
-                // may become valid in the future, and we don't want to
-                // disconnect a peer merely for serving us one too-far-ahead
-                // block header, to prevent an attacker from splitting the
-                // network by mining a block right at the 2 hour boundary.
-                //
-                // TODO: update the DoS logic (or, rather, rewrite the
-                // DoS-interface between validation and net_processing) so that
-                // the interface is cleaner, and so that we disconnect on all the
-                // reasons that a peer's headers chain is incompatible
-                // with ours (eg block->nVersion softforks, MTP violations,
-                // etc), and not just the duplicate-invalid case.
-                pfrom->fDisconnect = true;
-            }
+        if (state.IsInvalid()) {
+            MaybePunishNode(pfrom->GetId(), state, via_compact_block, "invalid header received");
             return false;
         }
     }
@@ -1727,13 +1778,13 @@ void static ProcessOrphanTx(CConnman* connman, std::set<uint256>& orphan_work_se
         const CTransaction& orphanTx = *porphanTx;
         NodeId fromPeer = orphan_it->second.fromPeer;
         bool fMissingInputs2 = false;
-        // Use a dummy CValidationState so someone can't setup nodes to counter-DoS based on orphan
-        // resolution (that is, feeding people an invalid transaction based on LegitTxX in order to get
-        // anyone relaying LegitTxX banned)
-        CValidationState stateDummy;
+        // Use a new CValidationState because orphans come from different peers (and we call
+        // MaybePunishNode based on the source peer from the orphan map, not based on the peer
+        // that relayed the previous transaction).
+        CValidationState orphan_state;
 
         if (setMisbehaving.count(fromPeer)) continue;
-        if (AcceptToMemoryPool(mempool, stateDummy, porphanTx, &fMissingInputs2, &removed_txn, false /* bypass_limits */, 0 /* nAbsurdFee */)) {
+        if (AcceptToMemoryPool(mempool, orphan_state, porphanTx, &fMissingInputs2, &removed_txn, false /* bypass_limits */, 0 /* nAbsurdFee */)) {
             LogPrint(BCLog::MEMPOOL, "   accepted orphan tx %s\n", orphanHash.ToString());
             RelayTransaction(orphanTx, connman);
             for (unsigned int i = 0; i < orphanTx.vout.size(); i++) {
@@ -1747,17 +1798,18 @@ void static ProcessOrphanTx(CConnman* connman, std::set<uint256>& orphan_work_se
             EraseOrphanTx(orphanHash);
             done = true;
         } else if (!fMissingInputs2) {
-            int nDos = 0;
-            if (stateDummy.IsInvalid(nDos) && nDos > 0) {
+            if (orphan_state.IsInvalid()) {
                 // Punish peer that gave us an invalid orphan tx
-                Misbehaving(fromPeer, nDos);
-                setMisbehaving.insert(fromPeer);
+                if (MaybePunishNode(fromPeer, orphan_state, /*via_compact_block*/ false)) {
+                    setMisbehaving.insert(fromPeer);
+                }
                 LogPrint(BCLog::MEMPOOL, "   invalid orphan tx %s\n", orphanHash.ToString());
             }
             // Has inputs but not accepted to mempool
             // Probably non-standard or insufficient fee
             LogPrint(BCLog::MEMPOOL, "   removed orphan tx %s\n", orphanHash.ToString());
-            if (!orphanTx.HasWitness() && !stateDummy.CorruptionPossible()) {
+            assert(IsTransactionReason(orphan_state.GetReason()));
+            if (!orphanTx.HasWitness() && orphan_state.GetReason() != ValidationInvalidReason::TX_WITNESS_MUTATED) {
                 // Do not use rejection cache for witness transactions or
                 // witness-stripped transactions, as they can have been malleated.
                 // See https://github.com/bitcoin/bitcoin/issues/8279 for details.
@@ -2474,7 +2526,8 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 recentRejects->insert(tx.GetHash());
             }
         } else {
-            if (!tx.HasWitness() && !state.CorruptionPossible()) {
+            assert(IsTransactionReason(state.GetReason()));
+            if (!tx.HasWitness() && state.GetReason() != ValidationInvalidReason::TX_WITNESS_MUTATED) {
                 // Do not use rejection cache for witness transactions or
                 // witness-stripped transactions, as they can have been malleated.
                 // See https://github.com/bitcoin/bitcoin/issues/8279 for details.
@@ -2493,15 +2546,13 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 // to policy, allowing the node to function as a gateway for
                 // nodes hidden behind it.
                 //
-                // Never relay transactions that we would assign a non-zero DoS
-                // score for, as we expect peers to do the same with us in that
-                // case.
-                int nDoS = 0;
-                if (!state.IsInvalid(nDoS) || nDoS == 0) {
+                // Never relay transactions that might result in being
+                // disconnected (or banned).
+                if (state.IsInvalid() && TxRelayMayResultInDisconnect(state)) {
+                    LogPrintf("Not relaying invalid transaction %s from whitelisted peer=%d (%s)\n", tx.GetHash().ToString(), pfrom->GetId(), FormatStateMessage(state));
+                } else {
                     LogPrintf("Force relaying tx %s from whitelisted peer=%d\n", tx.GetHash().ToString(), pfrom->GetId());
                     RelayTransaction(tx, connman);
-                } else {
-                    LogPrintf("Not relaying invalid transaction %s from whitelisted peer=%d (%s)\n", tx.GetHash().ToString(), pfrom->GetId(), FormatStateMessage(state));
                 }
             }
         }
@@ -2526,8 +2577,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         // peer simply for relaying a tx that our recentRejects has caught,
         // regardless of false positives.
 
-        int nDoS = 0;
-        if (state.IsInvalid(nDoS))
+        if (state.IsInvalid())
         {
             LogPrint(BCLog::MEMPOOLREJ, "%s from peer=%d was not accepted: %s\n", tx.GetHash().ToString(),
                 pfrom->GetId(),
@@ -2536,9 +2586,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::REJECT, strCommand, (unsigned char)state.GetRejectCode(),
                                    state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), inv.hash));
             }
-            if (nDoS > 0) {
-                Misbehaving(pfrom->GetId(), nDoS);
-            }
+            MaybePunishNode(pfrom->GetId(), state, /*via_compact_block*/ false);
         }
         return true;
     }
@@ -2574,14 +2622,8 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         const CBlockIndex *pindex = nullptr;
         CValidationState state;
         if (!ProcessNewBlockHeaders({cmpctblock.header}, state, chainparams, &pindex)) {
-            int nDoS;
-            if (state.IsInvalid(nDoS)) {
-                if (nDoS > 0) {
-                    LOCK(cs_main);
-                    Misbehaving(pfrom->GetId(), nDoS, strprintf("Peer %d sent us invalid header via cmpctblock\n", pfrom->GetId()));
-                } else {
-                    LogPrint(BCLog::NET, "Peer %d sent us invalid header via cmpctblock\n", pfrom->GetId());
-                }
+            if (state.IsInvalid()) {
+                MaybePunishNode(pfrom->GetId(), state, /*via_compact_block*/ true, "invalid header via cmpctblock");
                 return true;
             }
         }
@@ -2731,7 +2773,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             // the peer if the header turns out to be for an invalid block.
             // Note that if a peer tries to build on an invalid chain, that
             // will be detected and the peer will be banned.
-            return ProcessHeadersMessage(pfrom, connman, {cmpctblock.header}, chainparams, /*punish_duplicate_invalid=*/false);
+            return ProcessHeadersMessage(pfrom, connman, {cmpctblock.header}, chainparams, /*via_compact_block=*/true);
         }
 
         if (fBlockReconstructed) {
@@ -2874,12 +2916,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
         }
 
-        // Headers received via a HEADERS message should be valid, and reflect
-        // the chain the peer is on. If we receive a known-invalid header,
-        // disconnect the peer if it is using one of our outbound connection
-        // slots.
-        bool should_punish = !pfrom->fInbound && !pfrom->m_manual_connection;
-        return ProcessHeadersMessage(pfrom, connman, headers, chainparams, should_punish);
+        return ProcessHeadersMessage(pfrom, connman, headers, chainparams, /*via_compact_block=*/false);
     }
 
     if (strCommand == NetMsgType::BLOCK)
diff --git a/src/test/txvalidation_tests.cpp b/src/test/txvalidation_tests.cpp
index 331c340b74..26ae7be202 100644
--- a/src/test/txvalidation_tests.cpp
+++ b/src/test/txvalidation_tests.cpp
@@ -52,10 +52,7 @@ BOOST_FIXTURE_TEST_CASE(tx_mempool_reject_coinbase, TestChain100Setup)
     // Check that the validation state reflects the unsuccessful attempt.
     BOOST_CHECK(state.IsInvalid());
     BOOST_CHECK_EQUAL(state.GetRejectReason(), "coinbase");
-
-    int nDoS;
-    BOOST_CHECK_EQUAL(state.IsInvalid(nDoS), true);
-    BOOST_CHECK_EQUAL(nDoS, 100);
+    BOOST_CHECK(state.GetReason() == ValidationInvalidReason::CONSENSUS);
 }
 
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/validation.cpp b/src/validation.cpp
index 1da79e09f6..ba9d6184ee 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -585,28 +585,28 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
 
     // Coinbase is only valid in a block, not as a loose transaction
     if (tx.IsCoinBase())
-        return state.DoS(100, false, REJECT_INVALID, "coinbase");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "coinbase");
 
     // Rather not work on nonstandard transactions (unless -testnet/-regtest)
     std::string reason;
     if (fRequireStandard && !IsStandardTx(tx, reason))
-        return state.DoS(0, false, REJECT_NONSTANDARD, reason);
+        return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false, REJECT_NONSTANDARD, reason);
 
     // Do not work on transactions that are too small.
     // A transaction with 1 segwit input and 1 P2WPHK output has non-witness size of 82 bytes.
     // Transactions smaller than this are not relayed to reduce unnecessary malloc overhead.
     if (::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) < MIN_STANDARD_TX_NONWITNESS_SIZE)
-        return state.DoS(0, false, REJECT_NONSTANDARD, "tx-size-small");
+        return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false, REJECT_NONSTANDARD, "tx-size-small");
 
     // Only accept nLockTime-using transactions that can be mined in the next
     // block; we don't want our mempool filled up with transactions that can't
     // be mined yet.
     if (!CheckFinalTx(tx, STANDARD_LOCKTIME_VERIFY_FLAGS))
-        return state.DoS(0, false, REJECT_NONSTANDARD, "non-final");
+        return state.Invalid(ValidationInvalidReason::TX_PREMATURE_SPEND, false, REJECT_NONSTANDARD, "non-final");
 
     // is it already in the memory pool?
     if (pool.exists(hash)) {
-        return state.Invalid(false, REJECT_DUPLICATE, "txn-already-in-mempool");
+        return state.Invalid(ValidationInvalidReason::TX_CONFLICT, false, REJECT_DUPLICATE, "txn-already-in-mempool");
     }
 
     // Check for conflicts with in-memory transactions
@@ -642,7 +642,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                     }
                 }
                 if (fReplacementOptOut) {
-                    return state.Invalid(false, REJECT_DUPLICATE, "txn-mempool-conflict");
+                    return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_DUPLICATE, "txn-mempool-conflict");
                 }
 
                 setConflicts.insert(ptxConflicting->GetHash());
@@ -672,7 +672,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                 for (size_t out = 0; out < tx.vout.size(); out++) {
                     // Optimistically just do efficient check of cache for outputs
                     if (pcoinsTip->HaveCoinInCache(COutPoint(hash, out))) {
-                        return state.Invalid(false, REJECT_DUPLICATE, "txn-already-known");
+                        return state.Invalid(ValidationInvalidReason::TX_CONFLICT, false, REJECT_DUPLICATE, "txn-already-known");
                     }
                 }
                 // Otherwise assume this might be an orphan tx for which we just haven't seen parents yet
@@ -695,7 +695,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
         // Must keep pool.cs for this unless we change CheckSequenceLocks to take a
         // CoinsViewCache instead of create its own
         if (!CheckSequenceLocks(pool, tx, STANDARD_LOCKTIME_VERIFY_FLAGS, &lp))
-            return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
+            return state.Invalid(ValidationInvalidReason::TX_PREMATURE_SPEND, false, REJECT_NONSTANDARD, "non-BIP68-final");
 
         CAmount nFees = 0;
         if (!Consensus::CheckTxInputs(tx, state, view, GetSpendHeight(view), nFees)) {
@@ -704,11 +704,11 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
 
         // Check for non-standard pay-to-script-hash in inputs
         if (fRequireStandard && !AreInputsStandard(tx, view))
-            return state.Invalid(false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
+            return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
 
         // Check for non-standard witness in P2WSH
         if (tx.HasWitness() && fRequireStandard && !IsWitnessStandard(tx, view))
-            return state.DoS(0, false, REJECT_NONSTANDARD, "bad-witness-nonstandard", true);
+            return state.Invalid(ValidationInvalidReason::TX_WITNESS_MUTATED, false, REJECT_NONSTANDARD, "bad-witness-nonstandard");
 
         int64_t nSigOpsCost = GetTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
 
@@ -731,27 +731,22 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                               fSpendsCoinbase, nSigOpsCost, lp);
         unsigned int nSize = entry.GetTxSize();
 
-        // Check that the transaction doesn't have an excessive number of
-        // sigops, making it impossible to mine. Since the coinbase transaction
-        // itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
-        // MAX_BLOCK_SIGOPS; we still consider this an invalid rather than
-        // merely non-standard transaction.
         if (nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST)
-            return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
+            return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops",
                 strprintf("%d", nSigOpsCost));
 
         CAmount mempoolRejectFee = pool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nSize);
         if (!bypass_limits && mempoolRejectFee > 0 && nModifiedFees < mempoolRejectFee) {
-            return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool min fee not met", false, strprintf("%d < %d", nModifiedFees, mempoolRejectFee));
+            return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_INSUFFICIENTFEE, "mempool min fee not met", strprintf("%d < %d", nModifiedFees, mempoolRejectFee));
         }
 
         // No transactions are allowed below minRelayTxFee except from disconnected blocks
         if (!bypass_limits && nModifiedFees < ::minRelayTxFee.GetFee(nSize)) {
-            return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "min relay fee not met", false, strprintf("%d < %d", nModifiedFees, ::minRelayTxFee.GetFee(nSize)));
+            return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_INSUFFICIENTFEE, "min relay fee not met", strprintf("%d < %d", nModifiedFees, ::minRelayTxFee.GetFee(nSize)));
         }
 
         if (nAbsurdFee && nFees > nAbsurdFee)
-            return state.Invalid(false,
+            return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false,
                 REJECT_HIGHFEE, "absurdly-high-fee",
                 strprintf("%d > %d", nFees, nAbsurdFee));
 
@@ -763,7 +758,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
         size_t nLimitDescendantSize = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
         std::string errString;
         if (!pool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
-            return state.DoS(0, false, REJECT_NONSTANDARD, "too-long-mempool-chain", false, errString);
+            return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_NONSTANDARD, "too-long-mempool-chain", errString);
         }
 
         // A transaction that spends outputs that would be replaced by it is invalid. Now
@@ -775,8 +770,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
             const uint256 &hashAncestor = ancestorIt->GetTx().GetHash();
             if (setConflicts.count(hashAncestor))
             {
-                return state.DoS(10, false,
-                                 REJECT_INVALID, "bad-txns-spends-conflicting-tx", false,
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-spends-conflicting-tx",
                                  strprintf("%s spends conflicting transaction %s",
                                            hash.ToString(),
                                            hashAncestor.ToString()));
@@ -818,8 +812,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                 CFeeRate oldFeeRate(mi->GetModifiedFee(), mi->GetTxSize());
                 if (newFeeRate <= oldFeeRate)
                 {
-                    return state.DoS(0, false,
-                            REJECT_INSUFFICIENTFEE, "insufficient fee", false,
+                    return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_INSUFFICIENTFEE, "insufficient fee",
                             strprintf("rejecting replacement %s; new feerate %s <= old feerate %s",
                                   hash.ToString(),
                                   newFeeRate.ToString(),
@@ -847,8 +840,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                     nConflictingSize += it->GetTxSize();
                 }
             } else {
-                return state.DoS(0, false,
-                        REJECT_NONSTANDARD, "too many potential replacements", false,
+                return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_NONSTANDARD, "too many potential replacements",
                         strprintf("rejecting replacement %s; too many potential replacements (%d > %d)\n",
                             hash.ToString(),
                             nConflictingCount,
@@ -867,8 +859,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                     // it's cheaper to just check if the new input refers to a
                     // tx that's in the mempool.
                     if (pool.exists(tx.vin[j].prevout.hash)) {
-                        return state.DoS(0, false,
-                                         REJECT_NONSTANDARD, "replacement-adds-unconfirmed", false,
+                        return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_NONSTANDARD, "replacement-adds-unconfirmed",
                                          strprintf("replacement %s adds unconfirmed input, idx %d",
                                                   hash.ToString(), j));
                     }
@@ -880,8 +871,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
             // transactions would not be paid for.
             if (nModifiedFees < nConflictingFees)
             {
-                return state.DoS(0, false,
-                                 REJECT_INSUFFICIENTFEE, "insufficient fee", false,
+                return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_INSUFFICIENTFEE, "insufficient fee",
                                  strprintf("rejecting replacement %s, less fees than conflicting txs; %s < %s",
                                           hash.ToString(), FormatMoney(nModifiedFees), FormatMoney(nConflictingFees)));
             }
@@ -891,8 +881,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
             CAmount nDeltaFees = nModifiedFees - nConflictingFees;
             if (nDeltaFees < ::incrementalRelayFee.GetFee(nSize))
             {
-                return state.DoS(0, false,
-                        REJECT_INSUFFICIENTFEE, "insufficient fee", false,
+                return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_INSUFFICIENTFEE, "insufficient fee",
                         strprintf("rejecting replacement %s, not enough additional fees to relay; %s < %s",
                               hash.ToString(),
                               FormatMoney(nDeltaFees),
@@ -913,8 +902,10 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
             if (!tx.HasWitness() && CheckInputs(tx, stateDummy, view, true, scriptVerifyFlags & ~(SCRIPT_VERIFY_WITNESS | SCRIPT_VERIFY_CLEANSTACK), true, false, txdata) &&
                 !CheckInputs(tx, stateDummy, view, true, scriptVerifyFlags & ~SCRIPT_VERIFY_CLEANSTACK, true, false, txdata)) {
                 // Only the witness is missing, so the transaction itself may be fine.
-                state.SetCorruptionPossible();
+                state.Invalid(ValidationInvalidReason::TX_WITNESS_MUTATED, false,
+                        state.GetRejectCode(), state.GetRejectReason(), state.GetDebugMessage());
             }
+            assert(IsTransactionReason(state.GetReason()));
             return false; // state filled in by CheckInputs
         }
 
@@ -971,7 +962,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
         if (!bypass_limits) {
             LimitMempoolSize(pool, gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
             if (!pool.exists(hash))
-                return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool full");
+                return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_INSUFFICIENTFEE, "mempool full");
         }
     }
 
@@ -1309,7 +1300,7 @@ void static InvalidChainFound(CBlockIndex* pindexNew) EXCLUSIVE_LOCKS_REQUIRED(c
 }
 
 void CChainState::InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) {
-    if (!state.CorruptionPossible()) {
+    if (state.GetReason() != ValidationInvalidReason::BLOCK_MUTATED) {
         pindex->nStatus |= BLOCK_FAILED_VALID;
         m_failed_blocks.insert(pindex);
         setDirtyBlockIndex.insert(pindex);
@@ -1377,6 +1368,9 @@ void InitScriptExecutionCache() {
  * which are matched. This is useful for checking blocks where we will likely never need the cache
  * entry again.
  *
+ * Note that we may set state.reason to NOT_STANDARD for extra soft-fork flags in flags, block-checking
+ * callers should probably reset it to CONSENSUS in such cases.
+ *
  * Non-static (and re-declared) in src/test/txvalidationcache_tests.cpp
  */
 bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheSigStore, bool cacheFullScriptStore, PrecomputedTransactionData& txdata, std::vector<CScriptCheck> *pvChecks) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
@@ -1432,22 +1426,26 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsVi
                         // Check whether the failure was caused by a
                         // non-mandatory script verification check, such as
                         // non-standard DER encodings or non-null dummy
-                        // arguments; if so, don't trigger DoS protection to
-                        // avoid splitting the network between upgraded and
-                        // non-upgraded nodes.
+                        // arguments; if so, ensure we return NOT_STANDARD
+                        // instead of CONSENSUS to avoid downstream users
+                        // splitting the network between upgraded and
+                        // non-upgraded nodes by banning CONSENSUS-failing
+                        // data providers.
                         CScriptCheck check2(coin.out, tx, i,
                                 flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS, cacheSigStore, &txdata);
                         if (check2())
-                            return state.Invalid(false, REJECT_NONSTANDARD, strprintf("non-mandatory-script-verify-flag (%s)", ScriptErrorString(check.GetScriptError())));
+                            return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false, REJECT_NONSTANDARD, strprintf("non-mandatory-script-verify-flag (%s)", ScriptErrorString(check.GetScriptError())));
                     }
-                    // Failures of other flags indicate a transaction that is
-                    // invalid in new blocks, e.g. an invalid P2SH. We DoS ban
-                    // such nodes as they are not following the protocol. That
-                    // said during an upgrade careful thought should be taken
-                    // as to the correct behavior - we may want to continue
-                    // peering with non-upgraded nodes even after soft-fork
-                    // super-majority signaling has occurred.
-                    return state.DoS(100,false, REJECT_INVALID, strprintf("mandatory-script-verify-flag-failed (%s)", ScriptErrorString(check.GetScriptError())));
+                    // MANDATORY flag failures correspond to
+                    // ValidationInvalidReason::CONSENSUS. Because CONSENSUS
+                    // failures are the most serious case of validation
+                    // failures, we may need to consider using
+                    // RECENT_CONSENSUS_CHANGE for any script failure that
+                    // could be due to non-upgraded nodes which we may want to
+                    // support, to avoid splitting the network (but this
+                    // depends on the details of how net_processing handles
+                    // such errors).
+                    return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, strprintf("mandatory-script-verify-flag-failed (%s)", ScriptErrorString(check.GetScriptError())));
                 }
             }
 
@@ -1807,7 +1805,7 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
     // re-enforce that rule here (at least until we make it impossible for
     // GetAdjustedTime() to go backward).
     if (!CheckBlock(block, state, chainparams.GetConsensus(), !fJustCheck, !fJustCheck)) {
-        if (state.CorruptionPossible()) {
+        if (state.GetReason() == ValidationInvalidReason::BLOCK_MUTATED) {
             // We don't write down blocks to disk if they may have been
             // corrupted, so this should be impossible unless we're having hardware
             // problems.
@@ -1942,7 +1940,7 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
         for (const auto& tx : block.vtx) {
             for (size_t o = 0; o < tx->vout.size(); o++) {
                 if (view.HaveCoin(COutPoint(tx->GetHash(), o))) {
-                    return state.DoS(100, error("ConnectBlock(): tried to overwrite transaction"),
+                    return state.Invalid(ValidationInvalidReason::CONSENSUS, error("ConnectBlock(): tried to overwrite transaction"),
                                      REJECT_INVALID, "bad-txns-BIP30");
                 }
             }
@@ -1982,11 +1980,19 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
         {
             CAmount txfee = 0;
             if (!Consensus::CheckTxInputs(tx, state, view, pindex->nHeight, txfee)) {
+                if (!IsBlockReason(state.GetReason())) {
+                    // CheckTxInputs may return MISSING_INPUTS or
+                    // PREMATURE_SPEND but we can't return that, as it's not
+                    // defined for a block, so we reset the reason flag to
+                    // CONSENSUS here.
+                    state.Invalid(ValidationInvalidReason::CONSENSUS, false,
+                            state.GetRejectCode(), state.GetRejectReason(), state.GetDebugMessage());
+                }
                 return error("%s: Consensus::CheckTxInputs: %s, %s", __func__, tx.GetHash().ToString(), FormatStateMessage(state));
             }
             nFees += txfee;
             if (!MoneyRange(nFees)) {
-                return state.DoS(100, error("%s: accumulated fee in the block out of range.", __func__),
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, error("%s: accumulated fee in the block out of range.", __func__),
                                  REJECT_INVALID, "bad-txns-accumulated-fee-outofrange");
             }
 
@@ -1999,7 +2005,7 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
             }
 
             if (!SequenceLocks(tx, nLockTimeFlags, &prevheights, *pindex)) {
-                return state.DoS(100, error("%s: contains a non-BIP68-final transaction", __func__),
+                return state.Invalid(ValidationInvalidReason::CONSENSUS, error("%s: contains a non-BIP68-final transaction", __func__),
                                  REJECT_INVALID, "bad-txns-nonfinal");
             }
         }
@@ -2010,7 +2016,7 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
         // * witness (when witness enabled in flags and excludes coinbase)
         nSigOpsCost += GetTransactionSigOpCost(tx, view, flags);
         if (nSigOpsCost > MAX_BLOCK_SIGOPS_COST)
-            return state.DoS(100, error("ConnectBlock(): too many sigops"),
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, error("ConnectBlock(): too many sigops"),
                              REJECT_INVALID, "bad-blk-sigops");
 
         txdata.emplace_back(tx);
@@ -2018,9 +2024,20 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
         {
             std::vector<CScriptCheck> vChecks;
             bool fCacheResults = fJustCheck; /* Don't cache results if we're actually connecting blocks (still consult the cache, though) */
-            if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults, fCacheResults, txdata[i], nScriptCheckThreads ? &vChecks : nullptr))
+            if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults, fCacheResults, txdata[i], nScriptCheckThreads ? &vChecks : nullptr)) {
+                if (state.GetReason() == ValidationInvalidReason::TX_NOT_STANDARD) {
+                    // CheckInputs may return NOT_STANDARD for extra flags we passed,
+                    // but we can't return that, as it's not defined for a block, so
+                    // we reset the reason flag to CONSENSUS here.
+                    // In the event of a future soft-fork, we may need to
+                    // consider whether rewriting to CONSENSUS or
+                    // RECENT_CONSENSUS_CHANGE would be more appropriate.
+                    state.Invalid(ValidationInvalidReason::CONSENSUS, false,
+                              state.GetRejectCode(), state.GetRejectReason(), state.GetDebugMessage());
+                }
                 return error("ConnectBlock(): CheckInputs on %s failed with %s",
                     tx.GetHash().ToString(), FormatStateMessage(state));
+            }
             control.Add(vChecks);
         }
 
@@ -2035,13 +2052,13 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
 
     CAmount blockReward = nFees + GetBlockSubsidy(pindex->nHeight, chainparams.GetConsensus());
     if (block.vtx[0]->GetValueOut() > blockReward)
-        return state.DoS(100,
+        return state.Invalid(ValidationInvalidReason::CONSENSUS,
                          error("ConnectBlock(): coinbase pays too much (actual=%d vs limit=%d)",
                                block.vtx[0]->GetValueOut(), blockReward),
                                REJECT_INVALID, "bad-cb-amount");
 
     if (!control.Wait())
-        return state.DoS(100, error("%s: CheckQueue failed", __func__), REJECT_INVALID, "block-validation-failed");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, error("%s: CheckQueue failed", __func__), REJECT_INVALID, "block-validation-failed");
     int64_t nTime4 = GetTimeMicros(); nTimeVerify += nTime4 - nTime2;
     LogPrint(BCLog::BENCH, "    - Verify %u txins: %.2fms (%.3fms/txin) [%.2fs (%.2fms/blk)]\n", nInputs - 1, MILLI * (nTime4 - nTime2), nInputs <= 1 ? 0 : MILLI * (nTime4 - nTime2) / (nInputs-1), nTimeVerify * MICRO, nTimeVerify * MILLI / nBlocksTotal);
 
@@ -2569,7 +2586,7 @@ bool CChainState::ActivateBestChainStep(CValidationState& state, const CChainPar
             if (!ConnectTip(state, chainparams, pindexConnect, pindexConnect == pindexMostWork ? pblock : std::shared_ptr<const CBlock>(), connectTrace, disconnectpool)) {
                 if (state.IsInvalid()) {
                     // The block violates a consensus rule.
-                    if (!state.CorruptionPossible()) {
+                    if (state.GetReason() != ValidationInvalidReason::BLOCK_MUTATED) {
                         InvalidChainFound(vpindexToConnect.front());
                     }
                     state = CValidationState();
@@ -3067,7 +3084,7 @@ static bool CheckBlockHeader(const CBlockHeader& block, CValidationState& state,
 {
     // Check proof of work matches claimed amount
     if (fCheckPOW && !CheckProofOfWork(block.GetHash(), block.nBits, consensusParams))
-        return state.DoS(50, false, REJECT_INVALID, "high-hash", false, "proof of work failed");
+        return state.Invalid(ValidationInvalidReason::BLOCK_INVALID_HEADER, false, REJECT_INVALID, "high-hash", "proof of work failed");
 
     return true;
 }
@@ -3089,13 +3106,13 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
         bool mutated;
         uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
         if (block.hashMerkleRoot != hashMerkleRoot2)
-            return state.DoS(100, false, REJECT_INVALID, "bad-txnmrklroot", true, "hashMerkleRoot mismatch");
+            return state.Invalid(ValidationInvalidReason::BLOCK_MUTATED, false, REJECT_INVALID, "bad-txnmrklroot", "hashMerkleRoot mismatch");
 
         // Check for merkle tree malleability (CVE-2012-2459): repeating sequences
         // of transactions in a block without affecting the merkle root of a block,
         // while still invalidating it.
         if (mutated)
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-duplicate", true, "duplicate transaction");
+            return state.Invalid(ValidationInvalidReason::BLOCK_MUTATED, false, REJECT_INVALID, "bad-txns-duplicate", "duplicate transaction");
     }
 
     // All potential-corruption validation must be done before we do any
@@ -3106,19 +3123,19 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
 
     // Size limits
     if (block.vtx.empty() || block.vtx.size() * WITNESS_SCALE_FACTOR > MAX_BLOCK_WEIGHT || ::GetSerializeSize(block, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * WITNESS_SCALE_FACTOR > MAX_BLOCK_WEIGHT)
-        return state.DoS(100, false, REJECT_INVALID, "bad-blk-length", false, "size limits failed");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-blk-length", "size limits failed");
 
     // First transaction must be coinbase, the rest must not be
     if (block.vtx.empty() || !block.vtx[0]->IsCoinBase())
-        return state.DoS(100, false, REJECT_INVALID, "bad-cb-missing", false, "first tx is not coinbase");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-cb-missing", "first tx is not coinbase");
     for (unsigned int i = 1; i < block.vtx.size(); i++)
         if (block.vtx[i]->IsCoinBase())
-            return state.DoS(100, false, REJECT_INVALID, "bad-cb-multiple", false, "more than one coinbase");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-cb-multiple", "more than one coinbase");
 
     // Check transactions
     for (const auto& tx : block.vtx)
         if (!CheckTransaction(*tx, state, true))
-            return state.Invalid(false, state.GetRejectCode(), state.GetRejectReason(),
+            return state.Invalid(state.GetReason(), false, state.GetRejectCode(), state.GetRejectReason(),
                                  strprintf("Transaction check failed (tx hash %s) %s", tx->GetHash().ToString(), state.GetDebugMessage()));
 
     unsigned int nSigOps = 0;
@@ -3127,7 +3144,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
         nSigOps += GetLegacySigOpCount(*tx);
     }
     if (nSigOps * WITNESS_SCALE_FACTOR > MAX_BLOCK_SIGOPS_COST)
-        return state.DoS(100, false, REJECT_INVALID, "bad-blk-sigops", false, "out-of-bounds SigOpCount");
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-blk-sigops", "out-of-bounds SigOpCount");
 
     if (fCheckPOW && fCheckMerkleRoot)
         block.fChecked = true;
@@ -3236,7 +3253,7 @@ static bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationSta
     // Check proof of work
     const Consensus::Params& consensusParams = params.GetConsensus();
     if (block.nBits != GetNextWorkRequired(pindexPrev, &block, consensusParams))
-        return state.DoS(100, false, REJECT_INVALID, "bad-diffbits", false, "incorrect proof of work");
+        return state.Invalid(ValidationInvalidReason::BLOCK_INVALID_HEADER, false, REJECT_INVALID, "bad-diffbits", "incorrect proof of work");
 
     // Check against checkpoints
     if (fCheckpointsEnabled) {
@@ -3245,23 +3262,23 @@ static bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationSta
         // MapBlockIndex.
         CBlockIndex* pcheckpoint = GetLastCheckpoint(params.Checkpoints());
         if (pcheckpoint && nHeight < pcheckpoint->nHeight)
-            return state.DoS(100, error("%s: forked chain older than last checkpoint (height %d)", __func__, nHeight), REJECT_CHECKPOINT, "bad-fork-prior-to-checkpoint");
+            return state.Invalid(ValidationInvalidReason::BLOCK_CHECKPOINT, error("%s: forked chain older than last checkpoint (height %d)", __func__, nHeight), REJECT_CHECKPOINT, "bad-fork-prior-to-checkpoint");
     }
 
     // Check timestamp against prev
     if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast())
-        return state.Invalid(false, REJECT_INVALID, "time-too-old", "block's timestamp is too early");
+        return state.Invalid(ValidationInvalidReason::BLOCK_INVALID_HEADER, false, REJECT_INVALID, "time-too-old", "block's timestamp is too early");
 
     // Check timestamp
     if (block.GetBlockTime() > nAdjustedTime + MAX_FUTURE_BLOCK_TIME)
-        return state.Invalid(false, REJECT_INVALID, "time-too-new", "block timestamp too far in the future");
+        return state.Invalid(ValidationInvalidReason::BLOCK_TIME_FUTURE, false, REJECT_INVALID, "time-too-new", "block timestamp too far in the future");
 
     // Reject outdated version blocks when 95% (75% on testnet) of the network has upgraded:
     // check for version 2, 3 and 4 upgrades
     if((block.nVersion < 2 && nHeight >= consensusParams.BIP34Height) ||
        (block.nVersion < 3 && nHeight >= consensusParams.BIP66Height) ||
        (block.nVersion < 4 && nHeight >= consensusParams.BIP65Height))
-            return state.Invalid(false, REJECT_OBSOLETE, strprintf("bad-version(0x%08x)", block.nVersion),
+            return state.Invalid(ValidationInvalidReason::BLOCK_INVALID_HEADER, false, REJECT_OBSOLETE, strprintf("bad-version(0x%08x)", block.nVersion),
                                  strprintf("rejected nVersion=0x%08x block", block.nVersion));
 
     return true;
@@ -3291,7 +3308,7 @@ static bool ContextualCheckBlock(const CBlock& block, CValidationState& state, c
     // Check that all transactions are finalized
     for (const auto& tx : block.vtx) {
         if (!IsFinalTx(*tx, nHeight, nLockTimeCutoff)) {
-            return state.DoS(10, false, REJECT_INVALID, "bad-txns-nonfinal", false, "non-final transaction");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-txns-nonfinal", "non-final transaction");
         }
     }
 
@@ -3301,7 +3318,7 @@ static bool ContextualCheckBlock(const CBlock& block, CValidationState& state, c
         CScript expect = CScript() << nHeight;
         if (block.vtx[0]->vin[0].scriptSig.size() < expect.size() ||
             !std::equal(expect.begin(), expect.end(), block.vtx[0]->vin[0].scriptSig.begin())) {
-            return state.DoS(100, false, REJECT_INVALID, "bad-cb-height", false, "block height mismatch in coinbase");
+            return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-cb-height", "block height mismatch in coinbase");
         }
     }
 
@@ -3323,11 +3340,11 @@ static bool ContextualCheckBlock(const CBlock& block, CValidationState& state, c
             // already does not permit it, it is impossible to trigger in the
             // witness tree.
             if (block.vtx[0]->vin[0].scriptWitness.stack.size() != 1 || block.vtx[0]->vin[0].scriptWitness.stack[0].size() != 32) {
-                return state.DoS(100, false, REJECT_INVALID, "bad-witness-nonce-size", true, strprintf("%s : invalid witness reserved value size", __func__));
+                return state.Invalid(ValidationInvalidReason::BLOCK_MUTATED, false, REJECT_INVALID, "bad-witness-nonce-size", strprintf("%s : invalid witness reserved value size", __func__));
             }
             CHash256().Write(hashWitness.begin(), 32).Write(&block.vtx[0]->vin[0].scriptWitness.stack[0][0], 32).Finalize(hashWitness.begin());
             if (memcmp(hashWitness.begin(), &block.vtx[0]->vout[commitpos].scriptPubKey[6], 32)) {
-                return state.DoS(100, false, REJECT_INVALID, "bad-witness-merkle-match", true, strprintf("%s : witness merkle commitment mismatch", __func__));
+                return state.Invalid(ValidationInvalidReason::BLOCK_MUTATED, false, REJECT_INVALID, "bad-witness-merkle-match", strprintf("%s : witness merkle commitment mismatch", __func__));
             }
             fHaveWitness = true;
         }
@@ -3337,7 +3354,7 @@ static bool ContextualCheckBlock(const CBlock& block, CValidationState& state, c
     if (!fHaveWitness) {
       for (const auto& tx : block.vtx) {
             if (tx->HasWitness()) {
-                return state.DoS(100, false, REJECT_INVALID, "unexpected-witness", true, strprintf("%s : unexpected witness data found", __func__));
+                return state.Invalid(ValidationInvalidReason::BLOCK_MUTATED, false, REJECT_INVALID, "unexpected-witness", strprintf("%s : unexpected witness data found", __func__));
             }
         }
     }
@@ -3349,7 +3366,7 @@ static bool ContextualCheckBlock(const CBlock& block, CValidationState& state, c
     // the block hash, so we couldn't mark the block as permanently
     // failed).
     if (GetBlockWeight(block) > MAX_BLOCK_WEIGHT) {
-        return state.DoS(100, false, REJECT_INVALID, "bad-blk-weight", false, strprintf("%s : weight limit failed", __func__));
+        return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, "bad-blk-weight", strprintf("%s : weight limit failed", __func__));
     }
 
     return true;
@@ -3369,7 +3386,7 @@ bool CChainState::AcceptBlockHeader(const CBlockHeader& block, CValidationState&
             if (ppindex)
                 *ppindex = pindex;
             if (pindex->nStatus & BLOCK_FAILED_MASK)
-                return state.Invalid(error("%s: block %s is marked invalid", __func__, hash.ToString()), 0, "duplicate");
+                return state.Invalid(ValidationInvalidReason::CACHED_INVALID, error("%s: block %s is marked invalid", __func__, hash.ToString()), 0, "duplicate");
             return true;
         }
 
@@ -3380,10 +3397,10 @@ bool CChainState::AcceptBlockHeader(const CBlockHeader& block, CValidationState&
         CBlockIndex* pindexPrev = nullptr;
         BlockMap::iterator mi = mapBlockIndex.find(block.hashPrevBlock);
         if (mi == mapBlockIndex.end())
-            return state.DoS(10, error("%s: prev block not found", __func__), 0, "prev-blk-not-found");
+            return state.Invalid(ValidationInvalidReason::BLOCK_MISSING_PREV, error("%s: prev block not found", __func__), 0, "prev-blk-not-found");
         pindexPrev = (*mi).second;
         if (pindexPrev->nStatus & BLOCK_FAILED_MASK)
-            return state.DoS(100, error("%s: prev block invalid", __func__), REJECT_INVALID, "bad-prevblk");
+            return state.Invalid(ValidationInvalidReason::BLOCK_INVALID_PREV, error("%s: prev block invalid", __func__), REJECT_INVALID, "bad-prevblk");
         if (!ContextualCheckBlockHeader(block, state, chainparams, pindexPrev, GetAdjustedTime()))
             return error("%s: Consensus::ContextualCheckBlockHeader: %s, %s", __func__, hash.ToString(), FormatStateMessage(state));
 
@@ -3420,7 +3437,7 @@ bool CChainState::AcceptBlockHeader(const CBlockHeader& block, CValidationState&
                         setDirtyBlockIndex.insert(invalid_walk);
                         invalid_walk = invalid_walk->pprev;
                     }
-                    return state.DoS(100, error("%s: prev block invalid", __func__), REJECT_INVALID, "bad-prevblk");
+                    return state.Invalid(ValidationInvalidReason::BLOCK_INVALID_PREV, error("%s: prev block invalid", __func__), REJECT_INVALID, "bad-prevblk");
                 }
             }
         }
@@ -3524,7 +3541,8 @@ bool CChainState::AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CVali
 
     if (!CheckBlock(block, state, chainparams.GetConsensus()) ||
         !ContextualCheckBlock(block, state, chainparams.GetConsensus(), pindex->pprev)) {
-        if (state.IsInvalid() && !state.CorruptionPossible()) {
+        assert(IsBlockReason(state.GetReason()));
+        if (state.IsInvalid() && state.GetReason() != ValidationInvalidReason::BLOCK_MUTATED) {
             pindex->nStatus |= BLOCK_FAILED_VALID;
             setDirtyBlockIndex.insert(pindex);
         }