htlcswitch/hodl: add flag BogusSettle

This commit adds a new hodl flag "BogusSettle" which will be used to
emulate a node trying to settle back an incoming HTLC with a fake
preimage.

htlcswitch/hodl/config.go

@@ -21,6 +21,8 @@ type Config struct {
 	FailOutgoing bool `long:"fail-outgoing" description:"Instructs the node to drop outgoing FAILs before applying them to the channel state"`
 
 	Commit bool `long:"commit" description:"Instructs the node to add HTLCs to its local commitment state and to open circuits for any ADDs, but abort before committing the changes"`
+
+	BogusSettle bool `long:"bogus-settle" description:"Instructs the node to settle back any incoming HTLC with a bogus preimage"`
 }
 
 // Mask extracts the flags specified in the configuration, composing a Mask from
@@ -52,6 +54,9 @@ func (c *Config) Mask() Mask {
 	if c.Commit {
 		flags = append(flags, Commit)
 	}
+	if c.BogusSettle {
+		flags = append(flags, BogusSettle)
+	}
 
 	// NOTE: The value returned here will only honor the configuration if
 	// the debug build flag is present. In production, this method always

htlcswitch/hodl/flags.go

@@ -51,6 +51,10 @@ const (
 	// Commit drops all HTLC after any outgoing circuits have been
 	// opened, but before the in-memory commitment state is persisted.
 	Commit
+
+	// BogusSettle attempts to settle back any incoming HTLC for which we
+	// are the exit node with a bogus preimage.
+	BogusSettle
 )
 
 // String returns a human-readable identifier for a given Flag.
@@ -72,6 +76,8 @@ func (f Flag) String() string {
 		return "FailOutgoing"
 	case Commit:
 		return "Commit"
+	case BogusSettle:
+		return "BogusSettle"
 	default:
 		return "UnknownHodlFlag"
 	}
@@ -98,6 +104,8 @@ func (f Flag) Warning() string {
 		msg = "will not update channel state with downstream FAIL"
 	case Commit:
 		msg = "will not commit pending channel updates"
+	case BogusSettle:
+		msg = "will settle HTLC with bogus preimage"
 	default:
 		msg = "incorrect hodl flag usage"
 	}

htlcswitch/hodl/mask_test.go

@@ -67,6 +67,7 @@ var hodlMaskTests = []struct {
 			hodl.SettleOutgoing,
 			hodl.FailOutgoing,
 			hodl.Commit,
+			hodl.BogusSettle,
 		),
 		flags: map[hodl.Flag]struct{}{
 			hodl.ExitSettle:     {},
@@ -77,6 +78,7 @@ var hodlMaskTests = []struct {
 			hodl.SettleOutgoing: {},
 			hodl.FailOutgoing:   {},
 			hodl.Commit:         {},
+			hodl.BogusSettle:    {},
 		},
 	},
 }