use tfCronUnset to delete Cron

src/ripple/app/tx/impl/SetCron.cpp

@@ -45,7 +45,7 @@ SetCron::preflight(PreflightContext const& ctx)
     auto& tx = ctx.tx;
     auto& j = ctx.j;
 
-    if (tx.getFlags() & tfUniversalMask)
+    if (tx.getFlags() & tfCronSetMask)
     {
         JLOG(j.warn()) << "SetCron: Invalid flags set.";
         return temINVALID_FLAG;
@@ -55,7 +55,8 @@ SetCron::preflight(PreflightContext const& ctx)
     // DR - Set Cron with Delay and Repeat
     // D- - Set Cron (once off) with Delay only (repat implicitly 0)
     // -R - Invalid
-    // -- - Clear any existing cron (succeeds even if there isn't one)
+    // -- - Clear any existing cron (succeeds even if there isn't one) / with
+    // tfCronUnset flag set
 
     bool const hasDelay = tx.isFieldPresent(sfDelaySeconds);
     bool const hasRepeat = tx.isFieldPresent(sfRepeatCount);
@@ -90,12 +91,33 @@ SetCron::preflight(PreflightContext const& ctx)
         }
     }
 
+    if (tx.isFlag(tfCronUnset))
+    {
+        if (hasDelay || hasRepeat)
+        {
+            JLOG(j.warn()) << "SetCron: tfCronUnset flag cannot be used with "
+                              "DelaySeconds or RepeatCount.";
+            return temMALFORMED;
+        }
+    }
+
     return preflight2(ctx);
 }
 
 TER
 SetCron::preclaim(PreclaimContext const& ctx)
 {
+    if (ctx.tx.isFlag(tfCronUnset))
+    {
+        auto const account = ctx.tx.getAccountID(sfAccount);
+        auto const sle = ctx.view.read(keylet::account(account));
+        if (!sle)
+            return tefINTERNAL;
+
+        if (!sle->isFieldPresent(sfCron))
+            return tecNO_ENTRY;
+    }
+
     return tesSUCCESS;
 }
 
@@ -105,10 +127,7 @@ SetCron::doApply()
     auto& view = ctx_.view();
     auto const& tx = ctx_.tx;
 
-    bool const isDelete = !tx.isFieldPresent(sfDelaySeconds);
-
-    if (isDelete && tx.isFieldPresent(sfRepeatCount))
-        return tefINTERNAL;
+    bool const isDelete = tx.isFlag(tfCronUnset);
 
     // delay can be zero, in which case the cron will usually execute next
     // ledger.

src/ripple/protocol/TxFlags.h

@@ -200,6 +200,12 @@ constexpr std::uint32_t const tfImmutable = 1;
 // Clawback flags:
 constexpr std::uint32_t const tfClawbackMask = ~tfUniversal;
 
+// CronSet Flags:
+enum CronSetFlags : uint32_t {
+    tfCronUnset = 0x00000001,
+};
+constexpr std::uint32_t const tfCronSetMask = ~(tfUniversal | tfCronUnset);
+
 // clang-format on
 
 }  // namespace ripple

src/test/app/Cron_test.cpp

@@ -140,21 +140,24 @@ struct Cron_test : public beast::unit_test::suite
             // Invalid DelaySeconds and RepeatCount combination
             // (only RepeatCount specified)
             env(cron::set(alice), cron::repeat(256), ter(temMALFORMED));
-            env.close();
 
             // Invalid DelaySeconds
             env(cron::set(alice),
                 cron::delay(365 * 24 * 60 * 60 + 1),
                 cron::repeat(256),
                 ter(temMALFORMED));
-            env.close();
 
             // Invalid RepeatCount
             env(cron::set(alice),
                 cron::delay(365 * 24 * 60 * 60),
                 cron::repeat(257),
                 ter(temMALFORMED));
-            env.close();
+
+            // Invalid tfCronUnset flag
+            env(cron::set(alice),
+                cron::delay(365 * 24 * 60 * 60),
+                txflags(tfCronUnset),
+                ter(temMALFORMED));
         }
     }
 
@@ -165,8 +168,15 @@ struct Cron_test : public beast::unit_test::suite
         using namespace test::jtx;
         using namespace std::literals;
 
-        // no preclaim checks exists
-        BEAST_EXPECT(true);
+        auto const alice = Account("alice");
+        Env env{*this, features | featureCron};
+
+        env.fund(XRP(1000), alice);
+        env.close();
+
+        // Cron does not set
+        env(cron::set(alice), txflags(tfCronUnset), ter(tecNO_ENTRY));
+        env.close();
     }
 
     void
@@ -230,7 +240,10 @@ struct Cron_test : public beast::unit_test::suite
         BEAST_EXPECT(cronSle2->getFieldU32(sfRepeatCount) == 10);
 
         // delete cron
-        env(cron::set(alice), fee(XRP(1)), ter(tesSUCCESS));
+        env(cron::set(alice),
+            fee(XRP(1)),
+            txflags(tfCronUnset),
+            ter(tesSUCCESS));
         env.close();
 
         // owner count decremented