From aa6e5154dbd88a962f9d7d1ee4f6c6c936c62f0d Mon Sep 17 00:00:00 2001
From: Luke Dashjr <luke-jr+git@utopios.org>
Date: Fri, 5 Jan 2024 21:23:38 +0000
Subject: [PATCH] In unexpected version signalling warnings, list the specific
 bits involved

---
 src/validation.cpp                            | 24 +++++++++++++++----
 .../functional/feature_versionbits_warning.py |  7 +++---
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/validation.cpp b/src/validation.cpp
index 5c40d42391..dbb046d8ca 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2754,7 +2754,8 @@ void Chainstate::UpdateTip(const CBlockIndex* pindexNew)
         int unexpected_bit_count[VERSIONBITS_NUM_BITS], nonversionbit_count = 0;
         for (size_t i = 0; i < VERSIONBITS_NUM_BITS; ++i) unexpected_bit_count[i] = 0;
         static constexpr int WARNING_THRESHOLD = 100/2;
-        bool warning_threshold_hit = false;
+        std::set<uint8_t> warning_threshold_hit_bits;
+        int32_t warning_threshold_hit_int{-1};
         for (int i = 0; i < 100 && pindex != nullptr; i++)
         {
             int32_t nExpectedVersion = m_chainman.m_versionbitscache.ComputeBlockVersion(pindex->pprev, params.GetConsensus());
@@ -2765,21 +2766,34 @@ void Chainstate::UpdateTip(const CBlockIndex* pindexNew)
                         const int32_t mask = 1 << bit;
                         if ((pindex->nVersion & mask) && !(nExpectedVersion & mask)) {
                             if (++unexpected_bit_count[bit] > WARNING_THRESHOLD) {
-                                warning_threshold_hit = true;
+                                warning_threshold_hit_bits.insert(bit);
                             }
                         }
                     }
                 } else {
                     // Non-versionbits upgrade
                     if (++nonversionbit_count > WARNING_THRESHOLD) {
-                        warning_threshold_hit = true;
+                        if (warning_threshold_hit_int == -1) {
+                            warning_threshold_hit_int = pindex->nVersion;
+                        } else if (warning_threshold_hit_int != pindex->nVersion) {
+                            warning_threshold_hit_int = -2;
+                        }
                     }
                 }
             }
             pindex = pindex->pprev;
         }
-        if (warning_threshold_hit) {
-            const auto warning = _("Warning: Unrecognised block version being mined! Unknown rules may or may not be in effect");
+        if (!warning_threshold_hit_bits.empty()) {
+            const auto warning = strprintf(_("Warning: Miners are attempting to activate unknown new rules (bit %s)! You may or may not need to act to remain secure"), Join(warning_threshold_hit_bits, ", ", [](const uint8_t bit){ return ::ToString(int(bit)); }));
+            AppendWarning(warning_messages, warning);
+        }
+        if (warning_threshold_hit_int != -1) {
+            bilingual_str warning;
+            if (warning_threshold_hit_int == -2) {
+                warning = _("Warning: Unrecognised block versions are being mined! Unknown rules may or may not be in effect");
+            } else {
+                warning = strprintf(_("Warning: Unrecognised block version (0x%08x) is being mined! Unknown rules may or may not be in effect"), warning_threshold_hit_int);
+            }
             AppendWarning(warning_messages, warning);
         }
     }
diff --git a/test/functional/feature_versionbits_warning.py b/test/functional/feature_versionbits_warning.py
index 31292f3790..b8b43ef5bc 100755
--- a/test/functional/feature_versionbits_warning.py
+++ b/test/functional/feature_versionbits_warning.py
@@ -23,7 +23,8 @@ VB_UNKNOWN_VERSION = VB_TOP_BITS | (1 << VB_UNKNOWN_BIT)
 UNKNOWN_VERSION_SCHEMA = 0x60000000
 UNKNOWN_VERSION_SCHEMA_THRESHOLD = 51
 
-WARN_UNKNOWN_RULES_MINED = "Warning: Unrecognised block version being mined! Unknown rules may or may not be in effect"
+WARN_UNKNOWN_RULES_MINED = "Warning: Unrecognised block version (0x%08x) is being mined! Unknown rules may or may not be in effect" % (UNKNOWN_VERSION_SCHEMA,)
+WARN_UNKNOWN_BIT_MINED = f"Warning: Miners are attempting to activate unknown new rules (bit {VB_UNKNOWN_BIT})"
 WARN_UNKNOWN_RULES_ACTIVE = f"Unknown new rules activated (versionbit {VB_UNKNOWN_BIT})"
 VB_PATTERN = re.compile("Unknown new rules activated.*versionbit")
 
@@ -103,8 +104,8 @@ class VersionBitsWarningTest(BitcoinTestFramework):
         self.generatetoaddress(node, VB_PERIOD - VB_THRESHOLD, node_deterministic_address)
 
         # Check that get*info() shows the 51/100 unknown block version error.
-        assert(WARN_UNKNOWN_RULES_MINED in node.getmininginfo()["warnings"])
-        assert(WARN_UNKNOWN_RULES_MINED in node.getnetworkinfo()["warnings"])
+        assert(WARN_UNKNOWN_BIT_MINED in node.getmininginfo()["warnings"])
+        assert(WARN_UNKNOWN_BIT_MINED in node.getnetworkinfo()["warnings"])
 
         self.log.info("Check that there is a warning if previous VB_BLOCKS have >=VB_THRESHOLD blocks with unknown versionbits version.")
         # Mine a period worth of expected blocks so the generic block-version warning