Revert "Merge branch 'main' into feature/remote-debug"

This reverts commit 6d6333058c, reversing
changes made to 446aded1f7.

util/net/env.go

@@ -0,0 +1,34 @@
+package net
+
+import (
+	"os"
+	"strconv"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/iface/netstack"
+)
+
+const (
+	envDisableCustomRouting = "NB_DISABLE_CUSTOM_ROUTING"
+)
+
+// CustomRoutingDisabled returns true if custom routing is disabled.
+// This will fall back to the operation mode before the exit node functionality was implemented.
+// In particular exclusion routes won't be set up and all dialers and listeners will use net.Dial and net.Listen, respectively.
+func CustomRoutingDisabled() bool {
+	if netstack.IsEnabled() {
+		return true
+	}
+
+	var customRoutingDisabled bool
+	if val := os.Getenv(envDisableCustomRouting); val != "" {
+		var err error
+		customRoutingDisabled, err = strconv.ParseBool(val)
+		if err != nil {
+			log.Warnf("failed to parse %s: %v", envDisableCustomRouting, err)
+		}
+	}
+
+	return customRoutingDisabled
+}