Chore: move find process name to a single part

component/process/process_darwin.go

@@ -0,0 +1,107 @@
+package process
+
+import (
+	"bytes"
+	"encoding/binary"
+	"net"
+	"path/filepath"
+	"syscall"
+	"unsafe"
+)
+
+const (
+	procpidpathinfo     = 0xb
+	procpidpathinfosize = 1024
+	proccallnumpidinfo  = 0x2
+)
+
+func findProcessName(network string, ip net.IP, port int) (string, error) {
+	var spath string
+	switch network {
+	case TCP:
+		spath = "net.inet.tcp.pcblist_n"
+	case UDP:
+		spath = "net.inet.udp.pcblist_n"
+	default:
+		return "", ErrInvalidNetwork
+	}
+
+	isIPv4 := ip.To4() != nil
+
+	value, err := syscall.Sysctl(spath)
+	if err != nil {
+		return "", err
+	}
+
+	buf := []byte(value)
+
+	// from darwin-xnu/bsd/netinet/in_pcblist.c:get_pcblist_n
+	// size/offset are round up (aligned) to 8 bytes in darwin
+	// rup8(sizeof(xinpcb_n)) + rup8(sizeof(xsocket_n)) +
+	// 2 * rup8(sizeof(xsockbuf_n)) + rup8(sizeof(xsockstat_n))
+	itemSize := 384
+	if network == TCP {
+		// rup8(sizeof(xtcpcb_n))
+		itemSize += 208
+	}
+	// skip the first xinpgen(24 bytes) block
+	for i := 24; i+itemSize <= len(buf); i += itemSize {
+		// offset of xinpcb_n and xsocket_n
+		inp, so := i, i+104
+
+		srcPort := binary.BigEndian.Uint16(buf[inp+18 : inp+20])
+		if uint16(port) != srcPort {
+			continue
+		}
+
+		// xinpcb_n.inp_vflag
+		flag := buf[inp+44]
+
+		var srcIP net.IP
+		switch {
+		case flag&0x1 > 0 && isIPv4:
+			// ipv4
+			srcIP = net.IP(buf[inp+76 : inp+80])
+		case flag&0x2 > 0 && !isIPv4:
+			// ipv6
+			srcIP = net.IP(buf[inp+64 : inp+80])
+		default:
+			continue
+		}
+
+		if !ip.Equal(srcIP) {
+			continue
+		}
+
+		// xsocket_n.so_last_pid
+		pid := readNativeUint32(buf[so+68 : so+72])
+		return getExecPathFromPID(pid)
+	}
+
+	return "", ErrNotFound
+}
+
+func getExecPathFromPID(pid uint32) (string, error) {
+	buf := make([]byte, procpidpathinfosize)
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS_PROC_INFO,
+		proccallnumpidinfo,
+		uintptr(pid),
+		procpidpathinfo,
+		0,
+		uintptr(unsafe.Pointer(&buf[0])),
+		procpidpathinfosize)
+	if errno != 0 {
+		return "", errno
+	}
+	firstZero := bytes.IndexByte(buf, 0)
+	if firstZero <= 0 {
+		return "", nil
+	}
+
+	return filepath.Base(string(buf[:firstZero])), nil
+}
+
+func readNativeUint32(b []byte) uint32 {
+	return *(*uint32)(unsafe.Pointer(&b[0]))
+}