semver matching for dcrd/dcrwallet RPC versions

rpc/dcrd.go

@@ -14,8 +14,8 @@ import (
 	"github.com/jrick/wsrpc/v2"
 )
 
-const (
-	requiredDcrdVersion = "6.1.2"
+var (
+	requiredDcrdVersion = semver{Major: 6, Minor: 1, Patch: 2}
 )
 
 // These error codes are defined in dcrd/dcrjson. They are copied here so we
@@ -60,13 +60,16 @@ func (d *DcrdConnect) Client(ctx context.Context, netParams *chaincfg.Params) (*
 	if err != nil {
 		return nil, fmt.Errorf("dcrd version check failed: %v", err)
 	}
-	dcrdVersion, exists := verMap["dcrdjsonrpcapi"]
+
+	ver, exists := verMap["dcrdjsonrpcapi"]
 	if !exists {
 		return nil, fmt.Errorf("dcrd version response missing 'dcrdjsonrpcapi'")
 	}
-	if dcrdVersion.VersionString != requiredDcrdVersion {
-		return nil, fmt.Errorf("wrong dcrd RPC version: got %s, expected %s",
-			dcrdVersion.VersionString, requiredDcrdVersion)
+
+	sVer := semver{ver.Major, ver.Minor, ver.Patch}
+	if !semverCompatible(requiredDcrdVersion, sVer) {
+		return nil, fmt.Errorf("dcrd has incompatible JSON-RPC version: got %s, expected %s",
+			sVer, requiredDcrdVersion)
 	}
 
 	// Verify dcrd is on the correct network.

rpc/dcrwallet.go

@@ -10,8 +10,8 @@ import (
 	"github.com/decred/dcrd/wire"
 )
 
-const (
-	requiredWalletVersion = "8.1.0"
+var (
+	requiredWalletVersion = semver{Major: 8, Minor: 1, Patch: 0}
 )
 
 // WalletRPC provides methods for calling dcrwallet JSON-RPCs without exposing the details
@@ -70,16 +70,19 @@ func (w *WalletConnect) Clients(ctx context.Context, netParams *chaincfg.Params)
 			failedConnections = append(failedConnections, connect.addr)
 			continue
 		}
-		walletVersion, exists := verMap["dcrwalletjsonrpcapi"]
+
+		ver, exists := verMap["dcrwalletjsonrpcapi"]
 		if !exists {
 			log.Errorf("dcrwallet.Version response missing 'dcrwalletjsonrpcapi' (wallet=%s)",
 				c.String())
 			failedConnections = append(failedConnections, connect.addr)
 			continue
 		}
-		if walletVersion.VersionString != requiredWalletVersion {
-			log.Errorf("dcrwallet has wrong RPC version (wallet=%s): got %s, expected %s",
-				c.String(), walletVersion.VersionString, requiredWalletVersion)
+
+		sVer := semver{ver.Major, ver.Minor, ver.Patch}
+		if !semverCompatible(requiredWalletVersion, sVer) {
+			log.Errorf("dcrwallet has incompatible JSON-RPC version (wallet=%s): got %s, expected %s",
+				c.String(), sVer, requiredWalletVersion)
 			failedConnections = append(failedConnections, connect.addr)
 			continue
 		}

rpc/semver.go

@@ -0,0 +1,30 @@
+// Copyright (c) 2020 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package rpc
+
+import "fmt"
+
+type semver struct {
+	Major uint32
+	Minor uint32
+	Patch uint32
+}
+
+func semverCompatible(required, actual semver) bool {
+	switch {
+	case required.Major != actual.Major:
+		return false
+	case required.Minor > actual.Minor:
+		return false
+	case required.Minor == actual.Minor && required.Patch > actual.Patch:
+		return false
+	default:
+		return true
+	}
+}
+
+func (s semver) String() string {
+	return fmt.Sprintf("%d.%d.%d", s.Major, s.Minor, s.Patch)
+}