misc: small fix or general refactoring i did not bother commenting

modules/zerogod/zerogod_service.go

@@ -0,0 +1,100 @@
+package zerogod
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"github.com/bettercap/bettercap/v2/zeroconf"
+	"github.com/evilsocket/islazy/tui"
+)
+
+type ServiceData struct {
+	Name      string            `yaml:"name"`                // Instance name (e.g. "My web page")
+	Service   string            `yaml:"service"`             // Service name (e.g. _http._tcp.)
+	Domain    string            `yaml:"domain"`              // If blank, assumes "local"
+	Port      int               `yaml:"port"`                // Service port
+	Records   []string          `yaml:"records,omitempty"`   // Service DNS text records
+	Responder string            `yaml:"responder,omitempty"` // Optional IP to use instead of our tcp acceptor
+	IPP       map[string]string `yaml:"ipp,omitempty"`       // Optional IPP attributes map
+
+	server *zeroconf.Server
+}
+
+func (svc ServiceData) FullName() string {
+	return fmt.Sprintf("%s.%s.%s",
+		strings.Trim(svc.Name, "."),
+		strings.Trim(svc.Service, "."),
+		strings.Trim(svc.Domain, "."))
+}
+
+func (svc *ServiceData) Register(mod *ZeroGod) (err error) {
+	// now create it again to actually advertise
+	if svc.Responder == "" {
+		// use our own IP
+		if svc.server, err = zeroconf.Register(
+			svc.Name,
+			svc.Service,
+			svc.Domain,
+			svc.Port,
+			svc.Records,
+			nil); err != nil {
+			return fmt.Errorf("could not create service %s: %v", svc.FullName(), err)
+		}
+
+		mod.Info("advertising %s with responder=%s port=%d",
+			tui.Yellow(svc.FullName()),
+			tui.Red(svc.Responder),
+			svc.Port)
+	} else {
+		responderHostName := ""
+		// try first to do a reverse DNS of the ip
+		if addr, err := net.LookupAddr(svc.Responder); err == nil && len(addr) > 0 {
+			responderHostName = addr[0]
+		} else {
+			mod.Debug("could not get responder %s reverse dns entry: %v", svc.Responder, err)
+		}
+
+		// if we don't have a host, create a .nip.io representation
+		if responderHostName == "" {
+			responderHostName = fmt.Sprintf("%s.nip.io.", strings.ReplaceAll(svc.Responder, ".", "-"))
+		}
+
+		// use external responder
+		if svc.server, err = zeroconf.RegisterExternalResponder(
+			svc.Name,
+			svc.Service,
+			svc.Domain,
+			svc.Port,
+			responderHostName,
+			[]string{svc.Responder},
+			svc.Records,
+			nil); err != nil {
+			return fmt.Errorf("could not create service %s: %v", svc.FullName(), err)
+		}
+
+		mod.Info("advertising %s with responder=%s hostname=%s port=%d",
+			tui.Yellow(svc.FullName()),
+			tui.Red(svc.Responder),
+			tui.Yellow(responderHostName),
+			svc.Port)
+	}
+
+	return
+}
+
+func (svc *ServiceData) Unregister(mod *ZeroGod) error {
+	mod.Info("unregistering instance %s ...", tui.Yellow(svc.FullName()))
+
+	err := (error)(nil)
+	if svc.server == nil {
+		// if we haven't been registered yet, create the server
+		if svc.server, err = zeroconf.Register(svc.Name, svc.Service, svc.Domain, svc.Port, svc.Records, nil); err != nil {
+			return err
+		}
+	}
+
+	svc.server.Shutdown()
+
+	return nil
+}