vendor: add j-keck/arping

vendor/github.com/j-keck/arping/arping_bsd.go

@@ -0,0 +1,101 @@
+// +build darwin freebsd openbsd
+
+package arping
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"runtime"
+	"syscall"
+	"time"
+)
+
+var bpf *os.File
+var bpfFd int
+var buflen int
+
+var bpfArpFilter = []syscall.BpfInsn{
+	// make sure this is an arp packet
+	*syscall.BpfStmt(syscall.BPF_LD+syscall.BPF_H+syscall.BPF_ABS, 12),
+	*syscall.BpfJump(syscall.BPF_JMP+syscall.BPF_JEQ+syscall.BPF_K, 0x0806, 0, 1),
+	// if we passed all the tests, ask for the whole packet.
+	*syscall.BpfStmt(syscall.BPF_RET+syscall.BPF_K, -1),
+	// otherwise, drop it.
+	*syscall.BpfStmt(syscall.BPF_RET+syscall.BPF_K, 0),
+}
+
+func initialize(iface net.Interface) (err error) {
+	verboseLog.Println("search available /dev/bpfX")
+	for i := 0; i <= 10; i++ {
+		bpfPath := fmt.Sprintf("/dev/bpf%d", i)
+		bpf, err = os.OpenFile(bpfPath, os.O_RDWR, 0666)
+		if err != nil {
+			verboseLog.Printf("  open failed: %s - %s\n", bpfPath, err.Error())
+		} else {
+			verboseLog.Printf("  open success: %s\n", bpfPath)
+			break
+		}
+	}
+	bpfFd = int(bpf.Fd())
+	if bpfFd == -1 {
+		return errors.New("unable to open /dev/bpfX")
+	}
+
+	if err := syscall.SetBpfInterface(bpfFd, iface.Name); err != nil {
+		return err
+	}
+
+	if err := syscall.SetBpfImmediate(bpfFd, 1); err != nil {
+		return err
+	}
+
+	buflen, err = syscall.BpfBuflen(bpfFd)
+	if err != nil {
+		return err
+	}
+
+	if err := syscall.SetBpf(bpfFd, bpfArpFilter); err != nil {
+		return err
+	}
+
+	if err := syscall.FlushBpf(bpfFd); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func send(request arpDatagram) (time.Time, error) {
+	_, err := syscall.Write(bpfFd, request.MarshalWithEthernetHeader())
+	return time.Now(), err
+}
+
+func receive() (arpDatagram, time.Time, error) {
+	buffer := make([]byte, buflen)
+	n, err := syscall.Read(bpfFd, buffer)
+	if err != nil {
+		return arpDatagram{}, time.Now(), err
+	}
+
+	//
+	// FreeBSD uses a different bpf header (bh_tstamp differ in it's size)
+	// https://www.freebsd.org/cgi/man.cgi?bpf(4)#BPF_HEADER
+	//
+	var bpfHdrLength int
+	if runtime.GOOS == "freebsd" {
+		bpfHdrLength = 26
+	} else {
+		bpfHdrLength = 18
+	}
+
+	// skip bpf header + 14 bytes ethernet header
+	var hdrLength = bpfHdrLength + 14
+
+	return parseArpDatagram(buffer[hdrLength:n]), time.Now(), nil
+}
+
+func deinitialize() error {
+	return bpf.Close()
+}