improved proc monitors errors

 - Avoid sending duplicated errors.
 - Fixed sending error message when the ebpf events module fails to
   load.

Author: gustavo-iniguez-goya

daemon/procmon/ebpf/ebpf.go

@@ -131,15 +131,13 @@ func Start(ebpfOpts Config) *Error {
 	// load definitions from the elf file.
 	m, err = core.LoadEbpfModule("opensnitch.o", ebpfCfg.ModulesPath)
 	if err != nil {
-		dispatchErrorEvent(fmt.Sprint("[eBPF]: ", err.Error()))
 		return &Error{fmt.Errorf("[eBPF] Error loading opensnitch.o: %s", err.Error()), NotAvailable}
 	}
 	determineHostByteOrder()
 
 	// create objects from the definitions
 	ebpfMod := ebpfDefsT{}
 	if err := m.Assign(&ebpfMod); err != nil {
-		dispatchErrorEvent(fmt.Sprint("[eBPF] loadAndAssign error: ", err))
 		return &Error{fmt.Errorf("[eBPF] Error loading opensnitch.o (collection): %s", err), NotAvailable}
 	}
 	collectionMaps = append(collectionMaps, m)

daemon/procmon/ebpf/events.go

@@ -89,20 +89,17 @@ type eventsDefsT struct {
 func initEventsStreamer() *Error {
 	eventsColl, err := core.LoadEbpfModule("opensnitch-procs.o", ebpfCfg.ModulesPath)
 	if err != nil {
-		dispatchErrorEvent(fmt.Sprint("[eBPF events] collections: ", err))
 		return &Error{err, EventsNotAvailable}
 	}
 
 	ebpfMod := eventsDefsT{}
 	if err := eventsColl.Assign(&ebpfMod); err != nil {
-		dispatchErrorEvent(fmt.Sprint("[eBPF events] assign: ", err))
 		return &Error{err, EventsNotAvailable}
 	}
 	collectionMaps = append(collectionMaps, eventsColl)
 
 	// User space needs to perf_event_open() it (...) before eBPF program can send data into it.
 	if err := initPerfMap(ebpfMod.PerfEvents); err != nil {
-		dispatchErrorEvent(fmt.Sprint("[eBPF events] perfMap: ", err))
 		return &Error{err, EventsNotAvailable}
 	}
 

daemon/procmon/monitor/init.go

@@ -101,6 +101,7 @@ func Init(ebpfCfg ebpf.Config) (errm *Error) {
 		// XXX: this will have to be rewritten when we'll have more events (bind, listen, etc)
 		if err.What == ebpf.EventsNotAvailable {
 			errm.What = EbpfEventsErr
+			errm.Msg = err.Msg
 			log.Info("Process monitor method ebpf")
 			log.Warning("opensnitch-procs.o not available: %s", err.Msg)