Add maxjitter flag to hyp client

This to allow configurable time between knock sequence transmissions.  It's important the sequence arrive in the correct order, and some networks have multiple paths.

hyp/cmd/knock.go

@@ -38,6 +38,14 @@ Example usage:
 			panic(fmt.Errorf("failed to parse command flag 'secret': %w", err))
 		}
 
+		maxJitter, err := cmd.Flags().GetInt("maxjitter")
+		if err != nil {
+			panic(fmt.Errorf("failed to parse command flag 'maxjitter': %w", err))
+		}
+		if maxJitter < 1 || maxJitter > 1500 {
+			panic(fmt.Errorf("maxjitter must be value between 1 and 1500"))
+		}
+
 		secretBytes, err := os.ReadFile(secretFilePath)
 		if err != nil {
 			log.Fatalf("failed to read file 'hyp.secret': %v", err)
@@ -50,12 +58,12 @@ Example usage:
 		}
 
 		// Transmit
-		fmt.Println("Transmitting knock sequence:", ports)
 		for _, port := range ports {
+			fmt.Printf("knock | %s:%d\n", args[0], port)
 			conn, _ := net.Dial("udp", fmt.Sprintf("%s:%d", args[0], port))
 			conn.Write([]byte{0})
 			conn.Close()
-			time.Sleep(time.Millisecond * 200) // TBD: Make this configurable with flag (maxJitter)
+			time.Sleep(time.Millisecond * time.Duration(maxJitter)) // TBD: Make this configurable with flag (maxJitter)
 		}
 	},
 }
@@ -64,4 +72,5 @@ func init() {
 	rootCmd.AddCommand(knockCmd)
 
 	knockCmd.PersistentFlags().String("secret", "hyp.secret", "Path to the file containing the hyp secret.")
+	knockCmd.PersistentFlags().Int("maxjitter", 200, "Specifies the time in milliseconds between knock sequence transmissions.")
 }

hypd/cmd/secret.go

@@ -19,7 +19,7 @@ server and to clients.
 
 Example:
 
-hypd generatesecret > hyp.secret`,
+hypd generate secret > hyp.secret`,
 	Run: func(cmd *cobra.Command, args []string) {
 		sharedSecret, err := otphyp.GenerateSecret()
 		if err != nil {

hypd/server/hyp_bpf_bpfeb.go

@@ -0,0 +1,125 @@
+// Code generated by bpf2go; DO NOT EDIT.
+//go:build mips || mips64 || ppc64 || s390x
+
+package server
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"io"
+
+	"github.com/cilium/ebpf"
+)
+
+type hyp_bpfKnockData struct {
+	Srcip   uint32
+	Dstport uint16
+	Pad     uint16
+}
+
+// loadHyp_bpf returns the embedded CollectionSpec for hyp_bpf.
+func loadHyp_bpf() (*ebpf.CollectionSpec, error) {
+	reader := bytes.NewReader(_Hyp_bpfBytes)
+	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("can't load hyp_bpf: %w", err)
+	}
+
+	return spec, err
+}
+
+// loadHyp_bpfObjects loads hyp_bpf and converts it into a struct.
+//
+// The following types are suitable as obj argument:
+//
+//	*hyp_bpfObjects
+//	*hyp_bpfPrograms
+//	*hyp_bpfMaps
+//
+// See ebpf.CollectionSpec.LoadAndAssign documentation for details.
+func loadHyp_bpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
+	spec, err := loadHyp_bpf()
+	if err != nil {
+		return err
+	}
+
+	return spec.LoadAndAssign(obj, opts)
+}
+
+// hyp_bpfSpecs contains maps and programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type hyp_bpfSpecs struct {
+	hyp_bpfProgramSpecs
+	hyp_bpfMapSpecs
+}
+
+// hyp_bpfSpecs contains programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type hyp_bpfProgramSpecs struct {
+	XdpProgFunc *ebpf.ProgramSpec `ebpf:"xdp_prog_func"`
+}
+
+// hyp_bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type hyp_bpfMapSpecs struct {
+	Rb *ebpf.MapSpec `ebpf:"rb"`
+}
+
+// hyp_bpfObjects contains all objects after they have been loaded into the kernel.
+//
+// It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type hyp_bpfObjects struct {
+	hyp_bpfPrograms
+	hyp_bpfMaps
+}
+
+func (o *hyp_bpfObjects) Close() error {
+	return _Hyp_bpfClose(
+		&o.hyp_bpfPrograms,
+		&o.hyp_bpfMaps,
+	)
+}
+
+// hyp_bpfMaps contains all maps after they have been loaded into the kernel.
+//
+// It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type hyp_bpfMaps struct {
+	Rb *ebpf.Map `ebpf:"rb"`
+}
+
+func (m *hyp_bpfMaps) Close() error {
+	return _Hyp_bpfClose(
+		m.Rb,
+	)
+}
+
+// hyp_bpfPrograms contains all programs after they have been loaded into the kernel.
+//
+// It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type hyp_bpfPrograms struct {
+	XdpProgFunc *ebpf.Program `ebpf:"xdp_prog_func"`
+}
+
+func (p *hyp_bpfPrograms) Close() error {
+	return _Hyp_bpfClose(
+		p.XdpProgFunc,
+	)
+}
+
+func _Hyp_bpfClose(closers ...io.Closer) error {
+	for _, closer := range closers {
+		if err := closer.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Do not access this directly.
+//
+//go:embed hyp_bpf_bpfeb.o
+var _Hyp_bpfBytes []byte

hypd/server/hyp_bpf_bpfel.go

@@ -0,0 +1,125 @@
+// Code generated by bpf2go; DO NOT EDIT.
+//go:build 386 || amd64 || arm || arm64 || loong64 || mips64le || mipsle || ppc64le || riscv64
+
+package server
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"io"
+
+	"github.com/cilium/ebpf"
+)
+
+type hyp_bpfKnockData struct {
+	Srcip   uint32
+	Dstport uint16
+	Pad     uint16
+}
+
+// loadHyp_bpf returns the embedded CollectionSpec for hyp_bpf.
+func loadHyp_bpf() (*ebpf.CollectionSpec, error) {
+	reader := bytes.NewReader(_Hyp_bpfBytes)
+	spec, err := ebpf.LoadCollectionSpecFromReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("can't load hyp_bpf: %w", err)
+	}
+
+	return spec, err
+}
+
+// loadHyp_bpfObjects loads hyp_bpf and converts it into a struct.
+//
+// The following types are suitable as obj argument:
+//
+//	*hyp_bpfObjects
+//	*hyp_bpfPrograms
+//	*hyp_bpfMaps
+//
+// See ebpf.CollectionSpec.LoadAndAssign documentation for details.
+func loadHyp_bpfObjects(obj interface{}, opts *ebpf.CollectionOptions) error {
+	spec, err := loadHyp_bpf()
+	if err != nil {
+		return err
+	}
+
+	return spec.LoadAndAssign(obj, opts)
+}
+
+// hyp_bpfSpecs contains maps and programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type hyp_bpfSpecs struct {
+	hyp_bpfProgramSpecs
+	hyp_bpfMapSpecs
+}
+
+// hyp_bpfSpecs contains programs before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type hyp_bpfProgramSpecs struct {
+	XdpProgFunc *ebpf.ProgramSpec `ebpf:"xdp_prog_func"`
+}
+
+// hyp_bpfMapSpecs contains maps before they are loaded into the kernel.
+//
+// It can be passed ebpf.CollectionSpec.Assign.
+type hyp_bpfMapSpecs struct {
+	Rb *ebpf.MapSpec `ebpf:"rb"`
+}
+
+// hyp_bpfObjects contains all objects after they have been loaded into the kernel.
+//
+// It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type hyp_bpfObjects struct {
+	hyp_bpfPrograms
+	hyp_bpfMaps
+}
+
+func (o *hyp_bpfObjects) Close() error {
+	return _Hyp_bpfClose(
+		&o.hyp_bpfPrograms,
+		&o.hyp_bpfMaps,
+	)
+}
+
+// hyp_bpfMaps contains all maps after they have been loaded into the kernel.
+//
+// It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type hyp_bpfMaps struct {
+	Rb *ebpf.Map `ebpf:"rb"`
+}
+
+func (m *hyp_bpfMaps) Close() error {
+	return _Hyp_bpfClose(
+		m.Rb,
+	)
+}
+
+// hyp_bpfPrograms contains all programs after they have been loaded into the kernel.
+//
+// It can be passed to loadHyp_bpfObjects or ebpf.CollectionSpec.LoadAndAssign.
+type hyp_bpfPrograms struct {
+	XdpProgFunc *ebpf.Program `ebpf:"xdp_prog_func"`
+}
+
+func (p *hyp_bpfPrograms) Close() error {
+	return _Hyp_bpfClose(
+		p.XdpProgFunc,
+	)
+}
+
+func _Hyp_bpfClose(closers ...io.Closer) error {
+	for _, closer := range closers {
+		if err := closer.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Do not access this directly.
+//
+//go:embed hyp_bpf_bpfel.o
+var _Hyp_bpfBytes []byte