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vmnet.go
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vmnet.go
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package vmnet
/*
#cgo CFLAGS: -framework vmnet
#cgo LDFLAGS: -framework vmnet
#include "go_vmnet.h"
*/
import "C"
import (
"errors"
"io"
"log"
"net"
"sync"
"unsafe"
)
var (
ErrGenericFailure = errors.New("vmnet: generic failure")
ErrOutOfMemory = errors.New("vmnet: out of memory")
ErrInvalidArgument = errors.New("vmnet: invalid argument")
ErrInterfaceSetupIsNotComplete = errors.New("vmnet: interface setup is not complete")
ErrPermissionDenied = errors.New("vmnet: permission denied")
ErrPacketSizeLargerThanMTU = errors.New("vmnet: packet size larger than MTU")
ErrBuffersExhaustedTemporarilyInKernel = errors.New("vmnet: buffers exhausted temporarily in kernel")
ErrPacketsLargerThanLimit = errors.New("vmnet: packets larger than limit")
errNoMorePackets = errors.New("vmnet: no more packets")
errNotWritten = errors.New("vmnet: packet not written")
)
var errCodesMap = map[int]error{
1001: ErrGenericFailure,
1002: ErrOutOfMemory,
1003: ErrInvalidArgument,
1004: ErrInterfaceSetupIsNotComplete,
1005: ErrPermissionDenied,
1006: ErrPacketSizeLargerThanMTU,
1007: ErrBuffersExhaustedTemporarilyInKernel,
1008: ErrPacketsLargerThanLimit,
2000: errNoMorePackets,
2001: errNotWritten,
}
func errCodeToErr(code int) error {
err := errCodesMap[code]
if err == nil {
err = ErrGenericFailure
}
return err
}
type EventType uint32
const (
packetsAvailableEvent EventType = 1 << 0
)
type Msg struct {
status int
buf []byte
pktSize int
pktFlags uint32
}
type Interface struct {
events chan Event
readC chan packet
closed bool
id string
macStr string
mac net.HardwareAddr
mtu uint64
maxPacketSize uint64
iref unsafe.Pointer
eventQ unsafe.Pointer
vmnetInterface *C.struct_vmnet_interface
*sync.RWMutex
}
type Event struct {
Type EventType
}
type packet struct {
buf []byte
flags uint32
err error
}
func NewInterface(id string) Interface {
vmi := Interface{}
cId := C.CString(id)
defer C.free(unsafe.Pointer(cId))
vmi.vmnetInterface = C.vmn_create(cId, unsafe.Pointer(&vmi))
vmi.readC = make(chan packet)
vmi.events = make(chan Event)
vmi.maxPacketSize = uint64(vmi.vmnetInterface.max_packet_size)
return vmi
}
func (iface Interface) Destroy() error {
status := C.vmn_destroy(unsafe.Pointer(iface.vmnetInterface))
if int(status) != 1000 {
return errCodeToErr(int(status))
}
iface.RLock()
defer iface.RUnlock()
close(iface.readC)
close(iface.events)
C.free(unsafe.Pointer(iface.vmnetInterface))
return nil
}
//export emitEvent
func emitEvent(ptr unsafe.Pointer, eventType uint32, nPktAvail uint64) {
iface := (*Interface)(ptr)
etype := EventType(eventType)
log.Printf("emitEvent, %v, %v, %v\n", ptr, eventType, nPktAvail)
switch etype {
case packetsAvailableEvent:
for i := 0; i < int(nPktAvail); i++ {
pkt, err := iface.readPacket()
if err == errNoMorePackets {
break
}
log.Println("write to chan")
iface.readC <- pkt
if err != nil {
break
}
}
default:
iface.events <- Event{Type: etype}
}
}
func (iface Interface) readPacket() (packet, error) {
var pkt packet
cMsg := C.vmn_read(unsafe.Pointer(iface.vmnetInterface))
if int(cMsg.status) != 1000 {
err := errCodeToErr(int(cMsg.status))
pkt.err = err
return pkt, err
}
pkt.buf = C.GoBytes(unsafe.Pointer(cMsg.buf), C.int(cMsg.pkt_size))
pkt.flags = uint32(cMsg.pkt_flags)
C.free(unsafe.Pointer(cMsg.buf))
C.free(unsafe.Pointer(cMsg))
return pkt, nil
}
func (iface Interface) ReadPacket() ([]byte, int, error) {
pkt, open := <-iface.readC
if !open {
return []byte{}, 0, io.EOF
}
if pkt.err != nil {
return []byte{}, 0, pkt.err
}
return pkt.buf, len(pkt.buf), nil
}
func (iface Interface) WritePacket(p []byte) (n int, err error) {
if uint64(len(p)) > iface.maxPacketSize {
log.Printf("len(p) > maxPacketsize, %d > %d\n", len(p), iface.maxPacketSize)
return 0, io.ErrShortWrite
}
iface.RLock()
defer iface.RUnlock()
if iface.closed {
log.Printf("closed\n")
return 0, io.EOF
}
cMsg := C.vmn_write(unsafe.Pointer(iface.vmnetInterface), (*C.uint8_t)(unsafe.Pointer(&p[0])), C.size_t(len(p)))
if int(cMsg.status) != 1000 {
return 0, errCodeToErr(int(cMsg.status))
}
return int(cMsg.pkt_size), nil
}