packetbeat/{beater,protos,sniffer}: allow assignment of protocols to interfaces

Previously the protocols association was held in a *protocols.ProtocolStruct in
common for all interfaces. This prevented individual interfaces that were only
associated with a subset of the protocols that were being captured from working
specifically on that subset. The new code moves the construction of the protocols
sets into setupSniffer where they are associated with the interface that will be
capturing them. They are then assigned to child sniffers in sniffer.New based on
the interface.

This change has no effect on the behaviour of packetbeat as it stands as configs
from packetbeat and from agent are only able to express the existence of a single
interface. Changes to configuration format/shape will enable multiple interfaces
to be enabled in packetbeat and within a single agent policy, making use of the
change here.

Author: efd6

CHANGELOG-developer.next.asciidoc

@@ -177,6 +177,7 @@ The list below covers the major changes between 7.0.0-rc2 and main only.
 - Add initial infrastructure for a caching enrichment processor. {pull}36619[36619]
 - Add file-backed cache for cache enrichment processor. {pull}36686[36686] {pull}36696[36696]
 - Elide retryable HTTP client construction in Filebeat HTTPJSON and CEL inputs if not needed. {pull}36916[36916]
+- Allow assignment of packetbeat protocols to interfaces. {issue}36574[36564] {pull}[]
 
 ==== Deprecated
 

packetbeat/beater/processor.go

@@ -153,10 +153,10 @@ func (p *processorFactory) Create(pipeline beat.PipelineConnector, cfg *conf.C)
 		return nil, err
 	}
 
-	watcher := &procs.ProcessesWatcher{}
+	var watch procs.ProcessesWatcher
 	// Enable the process watcher only if capturing live traffic
 	if config.Interfaces[0].File == "" {
-		err = watcher.Init(config.Procs)
+		err = watch.Init(config.Procs)
 		if err != nil {
 			logp.Critical(err.Error())
 			return nil, err
@@ -165,17 +165,11 @@ func (p *processorFactory) Create(pipeline beat.PipelineConnector, cfg *conf.C)
 		logp.Info("Process watcher disabled when file input is used")
 	}
 
-	logp.Debug("main", "Initializing protocol plugins")
-	protocols := protos.NewProtocols()
-	err = protocols.Init(false, publisher, watcher, config.Protocols, config.ProtocolsList)
-	if err != nil {
-		return nil, fmt.Errorf("failed to initialize protocol analyzers: %w", err)
-	}
-	flows, err := setupFlows(pipeline, watcher, config)
+	flows, err := setupFlows(pipeline, &watch, config)
 	if err != nil {
 		return nil, err
 	}
-	sniffer, err := setupSniffer(id, config, protocols, sniffer.DecodersFor(id, publisher, protocols, watcher, flows, config))
+	sniffer, err := setupSniffer(id, config, publisher, &watch, flows)
 	if err != nil {
 		return nil, err
 	}
@@ -185,7 +179,7 @@ func (p *processorFactory) Create(pipeline beat.PipelineConnector, cfg *conf.C)
 
 // setupFlows returns a *flows.Flows that will publish to the provided pipeline,
 // configured with cfg and process enrichment via the provided watcher.
-func setupFlows(pipeline beat.Pipeline, watcher *procs.ProcessesWatcher, cfg config.Config) (*flows.Flows, error) {
+func setupFlows(pipeline beat.Pipeline, watch *procs.ProcessesWatcher, cfg config.Config) (*flows.Flows, error) {
 	if !cfg.Flows.IsEnabled() {
 		return nil, nil
 	}
@@ -211,10 +205,10 @@ func setupFlows(pipeline beat.Pipeline, watcher *procs.ProcessesWatcher, cfg con
 		return nil, err
 	}
 
-	return flows.NewFlows(client.PublishAll, watcher, cfg.Flows)
+	return flows.NewFlows(client.PublishAll, watch, cfg.Flows)
 }
 
-func setupSniffer(id string, cfg config.Config, protocols *protos.ProtocolsStruct, decoders sniffer.Decoders) (*sniffer.Sniffer, error) {
+func setupSniffer(id string, cfg config.Config, pub *publish.TransactionPublisher, watch *procs.ProcessesWatcher, flows *flows.Flows) (*sniffer.Sniffer, error) {
 	icmp, err := cfg.ICMP()
 	if err != nil {
 		return nil, err
@@ -237,7 +231,15 @@ func setupSniffer(id string, cfg config.Config, protocols *protos.ProtocolsStruc
 		interfaces = append(interfaces, iface)
 	}
 
+	logp.Debug("main", "Initializing protocol plugins")
+	decoders := make(map[string]sniffer.Decoders)
 	for i, iface := range interfaces {
+		protocols := protos.NewProtocols()
+		err = protocols.InitFiltered(false, iface.Device, pub, watch, cfg.Protocols, cfg.ProtocolsList)
+		if err != nil {
+			return nil, fmt.Errorf("failed to initialize protocol analyzers for %s: %w", iface.Device, err)
+		}
+		decoders[iface.Device] = sniffer.DecodersFor(id, pub, protocols, watch, flows, cfg)
 		if iface.BpfFilter != "" || cfg.Flows.IsEnabled() {
 			continue
 		}

packetbeat/protos/protos.go

@@ -110,50 +110,45 @@ type reporterFactory interface {
 	CreateReporter(*conf.C) (func(beat.Event), error)
 }
 
-func (s ProtocolsStruct) Init(
-	testMode bool,
-	pub reporterFactory,
-	watcher *procs.ProcessesWatcher,
-	configs map[string]*conf.C,
-	listConfigs []*conf.C,
-) error {
-	if len(configs) > 0 {
+func (s ProtocolsStruct) Init(test bool, pub reporterFactory, watch *procs.ProcessesWatcher, cfgs map[string]*conf.C, list []*conf.C) error {
+	return s.InitFiltered(test, "", pub, watch, cfgs, list)
+}
+
+func (s ProtocolsStruct) InitFiltered(test bool, device string, pub reporterFactory, watch *procs.ProcessesWatcher, cfgs map[string]*conf.C, list []*conf.C) error {
+	if len(cfgs) != 0 {
 		cfgwarn.Deprecate("7.0.0", "dictionary style protocols configuration has been deprecated. Please use list-style protocols configuration.")
 	}
 
 	for proto := range protocolSyms {
 		logp.Debug("protos", "registered protocol plugin: %v", proto)
 	}
 
-	for name, config := range configs {
-		if err := s.configureProtocol(testMode, pub, watcher, name, config); err != nil {
+	for name, cfg := range cfgs {
+		err := s.configureProtocol(test, device, pub, watch, name, cfg)
+		if err != nil {
 			return err
 		}
 	}
 
-	for _, config := range listConfigs {
+	for _, cfg := range list {
 		module := struct {
 			Name string `config:"type" validate:"required"`
 		}{}
-		if err := config.Unpack(&module); err != nil {
+		err := cfg.Unpack(&module)
+		if err != nil {
 			return err
 		}
 
-		if err := s.configureProtocol(testMode, pub, watcher, module.Name, config); err != nil {
+		err = s.configureProtocol(test, device, pub, watch, module.Name, cfg)
+		if err != nil {
 			return err
 		}
 	}
 
 	return nil
 }
 
-func (s ProtocolsStruct) configureProtocol(
-	testMode bool,
-	pub reporterFactory,
-	watcher *procs.ProcessesWatcher,
-	name string,
-	config *conf.C,
-) error {
+func (s ProtocolsStruct) configureProtocol(test bool, device string, pub reporterFactory, watch *procs.ProcessesWatcher, name string, config *conf.C) error {
 	// XXX: icmp is special, ignore here :/
 	if name == "icmp" {
 		return nil
@@ -176,17 +171,31 @@ func (s ProtocolsStruct) configureProtocol(
 		return nil
 	}
 
+	if device != "" {
+		// This could happen earlier, but let any errors be found first.
+		var protocol struct {
+			Device string `config:"interface"`
+		}
+		err := config.Unpack(&protocol)
+		if err != nil {
+			return err
+		}
+		if protocol.Device != "" && protocol.Device != device {
+			return nil
+		}
+	}
+
 	var client beat.Client
 	results := func(beat.Event) {}
-	if !testMode {
+	if !test {
 		var err error
 		results, err = pub.CreateReporter(config)
 		if err != nil {
 			return err
 		}
 	}
 
-	inst, err := plugin(testMode, results, watcher, config)
+	inst, err := plugin(test, results, watch, config)
 	if err != nil {
 		logp.Err("Failed to register protocol plugin: %v", err)
 		return err
@@ -196,6 +205,30 @@ func (s ProtocolsStruct) configureProtocol(
 	return nil
 }
 
+func (s ProtocolsStruct) register(proto Protocol, client beat.Client, plugin Plugin) {
+	if _, exists := s.all[proto]; exists {
+		logp.Warn("Protocol (%s) plugin will overwritten by another plugin", proto.String())
+	}
+
+	s.all[proto] = protocolInstance{
+		client: client,
+		plugin: plugin,
+	}
+
+	success := false
+	if tcp, ok := plugin.(TCPPlugin); ok {
+		s.tcp[proto] = tcp
+		success = true
+	}
+	if udp, ok := plugin.(UDPPlugin); ok {
+		s.udp[proto] = udp
+		success = true
+	}
+	if !success {
+		logp.Warn("Protocol (%s) register failed, port: %v", proto.String(), plugin.GetPorts())
+	}
+}
+
 func (s ProtocolsStruct) GetTCP(proto Protocol) TCPPlugin {
 	plugin, exists := s.tcp[proto]
 	if !exists {
@@ -228,7 +261,7 @@ func (s ProtocolsStruct) GetAllUDP() map[Protocol]UDPPlugin {
 // and unencapsulated packets
 func (s ProtocolsStruct) BpfFilter(withVlans bool, withICMP bool) string {
 	// Sort the protocol IDs so that the return value is consistent.
-	var protos []int
+	protos := make([]int, 0, len(s.all))
 	for proto := range s.all {
 		protos = append(protos, int(proto))
 	}
@@ -272,27 +305,3 @@ func (s ProtocolsStruct) BpfFilter(withVlans bool, withICMP bool) string {
 	}
 	return filter
 }
-
-func (s ProtocolsStruct) register(proto Protocol, client beat.Client, plugin Plugin) {
-	if _, exists := s.all[proto]; exists {
-		logp.Warn("Protocol (%s) plugin will overwritten by another plugin", proto.String())
-	}
-
-	s.all[proto] = protocolInstance{
-		client: client,
-		plugin: plugin,
-	}
-
-	success := false
-	if tcp, ok := plugin.(TCPPlugin); ok {
-		s.tcp[proto] = tcp
-		success = true
-	}
-	if udp, ok := plugin.(UDPPlugin); ok {
-		s.udp[proto] = udp
-		success = true
-	}
-	if !success {
-		logp.Warn("Protocol (%s) register failed, port: %v", proto.String(), plugin.GetPorts())
-	}
-}

packetbeat/sniffer/sniffer.go

@@ -90,19 +90,24 @@ const (
 // only, but no device is opened yet. Accessing and configuring the actual device
 // is done by the Run method. The id parameter is used to specify the metric
 // collection ID for AF_PACKET sniffers on Linux.
-func New(id string, testMode bool, _ string, decoders Decoders, interfaces []config.InterfaceConfig) (*Sniffer, error) {
+func New(id string, testMode bool, _ string, decoders map[string]Decoders, interfaces []config.InterfaceConfig) (*Sniffer, error) {
 	s := &Sniffer{
 		sniffers: make([]sniffer, len(interfaces)),
 		log:      logp.NewLogger("sniffer"),
 	}
 
 	for i, iface := range interfaces {
+		dec, ok := decoders[iface.Device]
+		if !ok {
+			// This should never happen.
+			return nil, fmt.Errorf("no decoder for %s", iface.Device)
+		}
 		child := sniffer{
 			state:         atomic.MakeInt32(snifferInactive),
 			followDefault: iface.PollDefaultRoute > 0 && strings.HasPrefix(iface.Device, "default_route"),
 			id:            id,
 			idx:           i,
-			decoders:      decoders,
+			decoders:      dec,
 			log:           s.log,
 		}