1 files changed, 91 insertions, 76 deletions

diff --git a/src/consensus/validation.h b/src/consensus/validation.h
index 4920cdf881..e602b9d5f3 100644
--- a/src/consensus/validation.h
+++ b/src/consensus/validation.h
@@ -12,13 +12,12 @@
 #include <primitives/transaction.h>
 #include <primitives/block.h>
 
-/** A "reason" why something was invalid, suitable for determining whether the
-  * provider of the object should be banned/ignored/disconnected/etc.
+/** A "reason" why a transaction was invalid, suitable for determining whether the
+  * provider of the transaction should be banned/ignored/disconnected/etc.
   */
-enum class ValidationInvalidReason {
-    // txn and blocks:
-    NONE,                    //!< not actually invalid
-    CONSENSUS,               //!< invalid by consensus rules (excluding any below reasons)
+enum class TxValidationResult {
+    TX_RESULT_UNSET,         //!< initial value. Tx has not yet been rejected
+    TX_CONSENSUS,            //!< invalid by consensus rules
     /**
      * Invalid by a change to consensus rules more recent than SegWit.
      * Currently unused as there are no such consensus rule changes, and any download
@@ -26,18 +25,9 @@ enum class ValidationInvalidReason {
      * 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_RECENT_CONSENSUS_CHANGE,
     TX_NOT_STANDARD,          //!< didn't meet our local policy rules
-    TX_MISSING_INPUTS,        //!< a transaction was missing some of its inputs
+    TX_MISSING_INPUTS,        //!< 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
@@ -48,82 +38,107 @@ enum class ValidationInvalidReason {
     /**
      * 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
+     * Currently this is only used if the transaction already exists in the mempool or on chain.
      */
     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;
-}
+/** A "reason" why a block was invalid, suitable for determining whether the
+  * provider of the block 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 BlockValidationResult {
+    BLOCK_RESULT_UNSET,      //!< initial value. Block has not yet been rejected
+    BLOCK_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.
+     */
+    BLOCK_RECENT_CONSENSUS_CHANGE,
+    BLOCK_CACHED_INVALID,    //!< this block was cached as being invalid and we didn't store the reason 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
+};
 
-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 {
+
+/** Base class for capturing information about block/transaction validation. This is subclassed
+ *  by TxValidationState and BlockValidationState for validation information on transactions
+ *  and blocks respectively. */
+class ValidationState {
 private:
     enum mode_state {
         MODE_VALID,   //!< everything ok
         MODE_INVALID, //!< network rule violation (DoS value may be set)
         MODE_ERROR,   //!< run-time error
-    } mode;
-    ValidationInvalidReason m_reason;
-    std::string strRejectReason;
-    std::string strDebugMessage;
-public:
-    CValidationState() : mode(MODE_VALID), m_reason(ValidationInvalidReason::NONE) {}
-    bool Invalid(ValidationInvalidReason reasonIn, bool ret = false,
-            const std::string &strRejectReasonIn="",
-            const std::string &strDebugMessageIn="") {
-        m_reason = reasonIn;
-        strRejectReason = strRejectReasonIn;
-        strDebugMessage = strDebugMessageIn;
-        if (mode == MODE_ERROR)
-            return ret;
-        mode = MODE_INVALID;
-        return ret;
+    } m_mode;
+    std::string m_reject_reason;
+    std::string m_debug_message;
+protected:
+    void Invalid(const std::string &reject_reason="",
+                 const std::string &debug_message="")
+    {
+        m_reject_reason = reject_reason;
+        m_debug_message = debug_message;
+        if (m_mode != MODE_ERROR) m_mode = MODE_INVALID;
     }
-    bool Error(const std::string& strRejectReasonIn) {
-        if (mode == MODE_VALID)
-            strRejectReason = strRejectReasonIn;
-        mode = MODE_ERROR;
+public:
+    // ValidationState is abstract. Have a pure virtual destructor.
+    virtual ~ValidationState() = 0;
+
+    ValidationState() : m_mode(MODE_VALID) {}
+    bool Error(const std::string& reject_reason)
+    {
+        if (m_mode == MODE_VALID)
+            m_reject_reason = reject_reason;
+        m_mode = MODE_ERROR;
         return false;
     }
-    bool IsValid() const {
-        return mode == MODE_VALID;
-    }
-    bool IsInvalid() const {
-        return mode == MODE_INVALID;
+    bool IsValid() const { return m_mode == MODE_VALID; }
+    bool IsInvalid() const { return m_mode == MODE_INVALID; }
+    bool IsError() const { return m_mode == MODE_ERROR; }
+    std::string GetRejectReason() const { return m_reject_reason; }
+    std::string GetDebugMessage() const { return m_debug_message; }
+};
+
+inline ValidationState::~ValidationState() {};
+
+class TxValidationState : public ValidationState {
+private:
+    TxValidationResult m_result;
+public:
+    bool Invalid(TxValidationResult result,
+                 const std::string &reject_reason="",
+                 const std::string &debug_message="")
+    {
+        m_result = result;
+        ValidationState::Invalid(reject_reason, debug_message);
+        return false;
     }
-    bool IsError() const {
-        return mode == MODE_ERROR;
+    TxValidationResult GetResult() const { return m_result; }
+};
+
+class BlockValidationState : public ValidationState {
+private:
+    BlockValidationResult m_result;
+public:
+    bool Invalid(BlockValidationResult result,
+                 const std::string &reject_reason="",
+                 const std::string &debug_message="") {
+        m_result = result;
+        ValidationState::Invalid(reject_reason, debug_message);
+        return false;
     }
-    ValidationInvalidReason GetReason() const { return m_reason; }
-    std::string GetRejectReason() const { return strRejectReason; }
-    std::string GetDebugMessage() const { return strDebugMessage; }
+    BlockValidationResult GetResult() const { return m_result; }
 };
 
 // These implement the weight = (stripped_size * 4) + witness_size formula,