fix: fixPayChanV1 (#4717)

This change introduces a new fix amendment (`fixPayChanV1`) that prevents the creation of new `PaymentChannelCreate` transaction with a `CancelAfter` time less than the current ledger time. It piggy backs off of fix1571.

Once the amendment is activated, creating a new `PaymentChannel` will require that if you specify the `CancelAfter` time/value, that value must be greater than or equal to the current ledger time.

Currently users can create a payment channel where the `CancelAfter` time is before the current ledger time. This results in the payment channel being immediately closed on the next PaymentChannel transaction.

include/xrpl/protocol/detail/features.macro

@@ -32,6 +32,7 @@
 // If you add an amendment here, then do not forget to increment `numFeatures`
 // in include/xrpl/protocol/Feature.h.
 
+XRPL_FIX    (PayChanCancelAfter,         Supported::yes, VoteBehavior::DefaultNo)
 // Check flags in Credential transactions
 XRPL_FIX    (InvalidTxFlags,             Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FIX    (FrozenLPTokenTransfer,      Supported::yes, VoteBehavior::DefaultNo)

src/test/app/PayChan_test.cpp

@@ -402,6 +402,52 @@ struct PayChan_test : public beast::unit_test::suite
             BEAST_EXPECT(!channelExists(*env.current(), chan));
             BEAST_EXPECT(env.balance(alice) == preAlice + channelFunds);
         }
+        // fixPayChanCancelAfter
+        // CancelAfter should be greater than close time
+        {
+            for (bool const withFixPayChan : {true, false})
+            {
+                auto const amend = withFixPayChan
+                    ? features
+                    : features - fixPayChanCancelAfter;
+                Env env{*this, amend};
+                env.fund(XRP(10000), alice, bob);
+                env.close();
+
+                auto const pk = alice.pk();
+                auto const settleDelay = 100s;
+                auto const channelFunds = XRP(1000);
+                NetClock::time_point const cancelAfter =
+                    env.current()->info().parentCloseTime - 1s;
+                auto const txResult =
+                    withFixPayChan ? ter(tecEXPIRED) : ter(tesSUCCESS);
+                env(create(
+                        alice, bob, channelFunds, settleDelay, pk, cancelAfter),
+                    txResult);
+            }
+        }
+        // fixPayChanCancelAfter
+        // CancelAfter can be equal to the close time
+        {
+            for (bool const withFixPayChan : {true, false})
+            {
+                auto const amend = withFixPayChan
+                    ? features
+                    : features - fixPayChanCancelAfter;
+                Env env{*this, amend};
+                env.fund(XRP(10000), alice, bob);
+                env.close();
+
+                auto const pk = alice.pk();
+                auto const settleDelay = 100s;
+                auto const channelFunds = XRP(1000);
+                NetClock::time_point const cancelAfter =
+                    env.current()->info().parentCloseTime;
+                env(create(
+                        alice, bob, channelFunds, settleDelay, pk, cancelAfter),
+                    ter(tesSUCCESS));
+            }
+        }
     }
 
     void

src/xrpld/app/tx/detail/Escrow.cpp

@@ -76,18 +76,6 @@ namespace ripple {
 
 //------------------------------------------------------------------------------
 
-/** Has the specified time passed?
-
-    @param now  the current time
-    @param mark the cutoff point
-    @return true if \a now refers to a time strictly after \a mark, else false.
-*/
-static inline bool
-after(NetClock::time_point now, std::uint32_t mark)
-{
-    return now.time_since_epoch().count() > mark;
-}
-
 TxConsequences
 EscrowCreate::makeTxConsequences(PreflightContext const& ctx)
 {

src/xrpld/app/tx/detail/PayChan.cpp

@@ -252,6 +252,13 @@ PayChanCreate::doApply()
     if (!sle)
         return tefINTERNAL;
 
+    if (ctx_.view().rules().enabled(fixPayChanCancelAfter))
+    {
+        auto const closeTime = ctx_.view().info().parentCloseTime;
+        if (ctx_.tx[~sfCancelAfter] && after(closeTime, ctx_.tx[sfCancelAfter]))
+            return tecEXPIRED;
+    }
+
     auto const dst = ctx_.tx[sfDestination];
 
     // Create PayChan in ledger.

src/xrpld/ledger/View.h

@@ -592,6 +592,15 @@ deleteAMMTrustLine(
     std::optional<AccountID> const& ammAccountID,
     beast::Journal j);
 
+/** Has the specified time passed?
+
+    @param now  the current time
+    @param mark the cutoff point
+    @return true if \a now refers to a time strictly after \a mark, else false.
+*/
+bool
+after(NetClock::time_point now, std::uint32_t mark);
+
 }  // namespace ripple
 
 #endif

src/xrpld/ledger/detail/View.cpp

@@ -2123,4 +2123,10 @@ rippleCredit(
         saAmount.asset().value());
 }
 
+bool
+after(NetClock::time_point now, std::uint32_t mark)
+{
+    return now.time_since_epoch().count() > mark;
+}
+
 }  // namespace ripple