Don't allow builds with "...nomain" git tag to run on mainnet

The check is done by Makefile. In case if the current version string
contains `nomain` substring, -X main.noMainNet=true ldflag is used.

Makefile

@@ -16,7 +16,12 @@ DOCKER_HUB ?= spacemeshos
 DOCKER_IMAGE_REPO ?= go-spacemesh-dev
 DOCKER_IMAGE_VERSION ?= $(SHA)
 
-LDFLAGS = -ldflags "-X main.version=${VERSION} -X main.commit=${COMMIT} -X main.branch=${BRANCH}"
+C_LDFLAGS = -X main.version=${VERSION} -X main.commit=${COMMIT} -X main.branch=${BRANCH}
+ifneq (,$(findstring nomain,$(VERSION)))
+    C_LDFLAGS += -X main.noMainNet=true
+endif
+LDFLAGS = -ldflags "$(C_LDFLAGS)"
+
 include Makefile-libs.Inc
 
 UNIT_TESTS ?= $(shell go list ./...  | grep -v systest/tests | grep -v cmd/node | grep -v cmd/gen-p2p-identity | grep -v cmd/trace | grep -v genvm/cmd)

cmd/base.go

@@ -24,6 +24,9 @@ var (
 
 	// Commit is the git commit used to build the app. Designed to be overwritten by make.
 	Commit string
+
+	// Prohibit this build from running on the mainnet.
+	NoMainNet bool
 )
 
 // EnsureCLIFlags checks flag types and converts them.

cmd/node/main.go

@@ -12,15 +12,17 @@ import (
 )
 
 var (
-	version string
-	commit  string
-	branch  string
+	version   string
+	commit    string
+	branch    string
+	noMainNet string
 )
 
 func main() { // run the app
 	cmd.Version = version
 	cmd.Commit = commit
 	cmd.Branch = branch
+	cmd.NoMainNet = noMainNet == "true"
 	if err := node.GetCommand().Execute(); err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)

node/node.go

@@ -131,6 +131,11 @@ func GetCommand() *cobra.Command {
 			if conf.LOGGING.Encoder == config.JSONLogEncoder {
 				log.JSONLog(true)
 			}
+
+			if cmd.NoMainNet && onMainNet(conf) {
+				log.With().Fatal("this is a testnet-only build not intended for mainnet")
+			}
+
 			app := New(
 				WithConfig(conf),
 				// NOTE(dshulyak) this needs to be max level so that child logger can can be current level or below.
@@ -1576,3 +1581,7 @@ func (w tortoiseWeakCoin) Set(lid types.LayerID, value bool) error {
 	w.tortoise.OnWeakCoin(lid, value)
 	return nil
 }
+
+func onMainNet(conf *config.Config) bool {
+	return conf.Genesis.GenesisTime == config.MainnetConfig().Genesis.GenesisTime
+}