Adds Generic Middleware helper functions

modules/core/04-channel/types/version.go

@@ -0,0 +1,19 @@
+package types
+
+import "strings"
+
+// SplitChannelVersion middleware version will split the channel version string
+// into the outermost middleware version and the underlying app version.
+// It will use the default delimiter `:` for middleware versions.
+// In case there's no delimeter, this function returns an empty string for the middleware version (first return argument),
+// and the full input as the second underlying app version.
+func SplitChannelVersion(version string) (middlewareVersion, appVersion string) {
+	// only split out the first middleware version
+	splitVersions := strings.Split(version, ":")
+	if len(splitVersions) == 1 {
+		return "", version
+	}
+	middlewareVersion = splitVersions[0]
+	appVersion = strings.Join(splitVersions[1:], ":")
+	return
+}

modules/core/04-channel/types/version_test.go

@@ -0,0 +1,43 @@
+package types_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/cosmos/ibc-go/modules/core/04-channel/types"
+)
+
+func TestSplitVersions(t *testing.T) {
+	testCases := []struct {
+		name       string
+		version    string
+		mwVersion  string
+		appVersion string
+	}{
+		{
+			"single wrapped middleware",
+			"fee29-1:ics20-1",
+			"fee29-1",
+			"ics20-1",
+		},
+		{
+			"multiple wrapped middleware",
+			"fee29-1:whitelist:ics20-1",
+			"fee29-1",
+			"whitelist:ics20-1",
+		},
+		{
+			"no middleware",
+			"ics20-1",
+			"",
+			"ics20-1",
+		},
+	}
+
+	for _, tc := range testCases {
+		mwVersion, appVersion := types.SplitChannelVersion(tc.version)
+		require.Equal(t, tc.mwVersion, mwVersion, "middleware version is unexpected for case: %s", tc.name)
+		require.Equal(t, tc.appVersion, appVersion, "app version is unexpected for case: %s", tc.name)
+	}
+}

modules/core/24-host/keys.go

@@ -35,6 +35,7 @@ const (
 	KeyPortPrefix              = "ports"
 	KeySequencePrefix          = "sequences"
 	KeyChannelCapabilityPrefix = "capabilities"
+	KeyAppCapabilityPrefix     = "appCapabilities"
 	KeyNextSeqSendPrefix       = "nextSequenceSend"
 	KeyNextSeqRecvPrefix       = "nextSequenceRecv"
 	KeyNextSeqAckPrefix        = "nextSequenceAck"
@@ -142,6 +143,15 @@ func ChannelCapabilityPath(portID, channelID string) string {
 	return fmt.Sprintf("%s/%s", KeyChannelCapabilityPrefix, channelPath(portID, channelID))
 }
 
+// AppCapabilityPath defines the path under which application capabilities can be issued by
+// an ICS30 middleware wrapping an ICS26 application.
+// Note the app capability path is only the name the middleware uses to reference a capability it issues
+// to the underlying app. The underlying app will use the channel capability path to claim this capability
+// from middleware just as the original capability issued by IBC is claimed by middleware using channel capability path.
+func AppCapabilityPath(portID, channelID string) string {
+	return fmt.Sprintf("%s/%s", KeyAppCapabilityPrefix, channelPath(portID, channelID))
+}
+
 // NextSequenceSendPath defines the next send sequence counter store path
 func NextSequenceSendPath(portID, channelID string) string {
 	return fmt.Sprintf("%s/%s", KeyNextSeqSendPrefix, channelPath(portID, channelID))