Fix Praos obsolete node check

ouroboros-consensus-protocol/src/Ouroboros/Consensus/Protocol/Praos/Translate.hs

@@ -21,7 +21,7 @@ import           Ouroboros.Consensus.Protocol.Praos (ConsensusConfig (..),
                      Praos, PraosParams (..), PraosState (..),
                      Ticked (TickedPraosLedgerView))
 import           Ouroboros.Consensus.Protocol.Praos.Views
-                     (LedgerView (lvMaxBodySize, lvMaxHeaderSize))
+                     (LedgerView (lvMaxBodySize, lvMaxHeaderSize, lvProtocolVersion))
 import qualified Ouroboros.Consensus.Protocol.Praos.Views as Views
 import           Ouroboros.Consensus.Protocol.TPraos (TPraos, TPraosParams (..),
                      TPraosState (tpraosStateChainDepState, tpraosStateLastSlot))
@@ -70,7 +70,8 @@ instance
         Views.LedgerView
           { Views.lvPoolDistr = coercePoolDistr lvPoolDistr,
             lvMaxHeaderSize = SL.ccMaxBHSize lvChainChecks,
-            lvMaxBodySize = SL.ccMaxBBSize lvChainChecks
+            lvMaxBodySize = SL.ccMaxBBSize lvChainChecks,
+            lvProtocolVersion = SL.ccProtocolVersion lvChainChecks
           }
         where
           coercePoolDistr :: SL.PoolDistr c1 -> SL.PoolDistr c2

ouroboros-consensus-protocol/src/Ouroboros/Consensus/Protocol/Praos/Views.hs

@@ -7,6 +7,7 @@ module Ouroboros.Consensus.Protocol.Praos.Views (
 
 import           Cardano.Crypto.KES (SignedKES)
 import           Cardano.Crypto.VRF (CertifiedVRF, VRFAlgorithm (VerKeyVRF))
+import           Cardano.Ledger.BaseTypes (ProtVer)
 import           Cardano.Ledger.Crypto (KES, VRF)
 import           Cardano.Ledger.Keys (KeyRole (BlockIssuer), VKey)
 import qualified Cardano.Ledger.Shelley.API as SL
@@ -39,10 +40,12 @@ data HeaderView crypto = HeaderView
 
 data LedgerView crypto = LedgerView
   { -- | Stake distribution
-    lvPoolDistr     :: SL.PoolDistr crypto,
+    lvPoolDistr       :: SL.PoolDistr crypto,
     -- | Maximum header size
-    lvMaxHeaderSize :: !Natural,
+    lvMaxHeaderSize   :: !Natural,
     -- | Maximum block body size
-    lvMaxBodySize   :: !Natural
+    lvMaxBodySize     :: !Natural,
+    -- | Current protocol version
+    lvProtocolVersion :: !ProtVer
   }
   deriving (Show)

ouroboros-consensus-shelley/src/Ouroboros/Consensus/Shelley/Ledger/SupportsProtocol.hs

@@ -99,7 +99,8 @@ instance
           Praos.LedgerView
             { Praos.lvPoolDistr = nesPd,
               Praos.lvMaxBodySize = getField @"_maxBBSize" . SL.esPp $ nesEs,
-              Praos.lvMaxHeaderSize = getField @"_maxBHSize" . SL.esPp $ nesEs
+              Praos.lvMaxHeaderSize = getField @"_maxBHSize" . SL.esPp $ nesEs,
+              Praos.lvProtocolVersion = getField @"_protocolVersion" . SL.esPp $ nesEs
             }
 
   -- | Currently the Shelley+ ledger is hard-coded to produce a TPraos ledger

ouroboros-consensus-shelley/src/Ouroboros/Consensus/Shelley/Protocol/Praos.hs

@@ -73,8 +73,8 @@ instance PraosCrypto c => ProtocolHeaderSupportsEnvelope (Praos c) where
         BlockSizeTooLarge (bhviewBSize bhv) maxBodySize
     where
       pp = praosParams cfg
-      (MaxMajorProtVer m) = praosMaxMajorPV pp
-      (ProtVer maxpv _) = hbProtVer $ headerBody hdr
+      (MaxMajorProtVer maxpv) = praosMaxMajorPV pp
+      (ProtVer m _) = lvProtocolVersion lv
       maxHeaderSize = lvMaxHeaderSize lv
       maxBodySize = lvMaxBodySize lv
       bhv = mkHeaderView hdr

ouroboros-consensus/docs/interface-CHANGELOG.md

@@ -56,6 +56,21 @@ may appear out of chronological order.
 The internals of each entry are organized similar to
 https://keepachangelog.com/en/1.1.0/, adapted to our plan explained above.
 
+## Circa 2022-07-20
+
+### Fixed
+
+- The obsolete node check in the new 'Praos' protocol was not performing the
+  check that was intended. It is supposed to check that the current protocol
+  version is no greater than the max major protocol version. It was instead
+  checking that the max major protocol version was not greater than the
+  protocol version listed in the block header (which is currently not supposed
+  to have any semantic meaning, and is used to manually check the readiness
+  of the network for a hard fork). Note that this mistake is only in the Praos
+  protocol, not in TPraos. The consequence of this incorrect check is that
+  nodes will not properly halt after a hard fork when they do not have the
+  required software for the hard fork.
+
 ## Circa 2022-07-13
 
 ### Added