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package virtualnetwork
import (
"context"
"crypto/rand"
"encoding/binary"
"io"
"net"
"github.com/containers/gvisor-tap-vsock/pkg/types"
log "github.com/sirupsen/logrus"
"gvisor.dev/gvisor/pkg/tcpip/header"
)
func (n *VirtualNetwork) AcceptVpnKit(conn net.Conn) error {
if err := vpnkitHandshake(conn, n.configuration); err != nil {
log.Error(err)
}
_ = n.networkSwitch.Accept(context.Background(), conn, types.HyperKitProtocol)
return nil
}
func vpnkitHandshake(conn net.Conn, configuration *types.Configuration) error {
// https://github.com/moby/hyperkit/blob/2f061e447e1435cdf1b9eda364cea6414f2c606b/src/lib/pci_virtio_net_vpnkit.c#L91
msgInit := make([]byte, 49)
if _, err := io.ReadFull(conn, msgInit); err != nil {
return err
}
if _, err := conn.Write(msgInit); err != nil {
return err
}
// https://github.com/moby/hyperkit/blob/2f061e447e1435cdf1b9eda364cea6414f2c606b/src/lib/pci_virtio_net_vpnkit.c#L123
msgCommand := make([]byte, 41)
if _, err := io.ReadFull(conn, msgCommand); err != nil {
return err
}
vpnkitUUID := string(msgCommand[1:37])
log.Debugf("UUID sent by Hyperkit: %s", vpnkitUUID)
// https://github.com/moby/hyperkit/blob/2f061e447e1435cdf1b9eda364cea6414f2c606b/src/lib/pci_virtio_net_vpnkit.c#L131
resp := make([]byte, 258)
resp[0] = 0x01
mtu := uint16(configuration.MTU)
binary.LittleEndian.PutUint16(resp[1:3], mtu)
binary.LittleEndian.PutUint16(resp[3:5], mtu+header.EthernetMinimumSize)
mac, err := macAddr(configuration, vpnkitUUID)
if err != nil {
return err
}
log.Debugf("Sending mac address: %s", mac.String())
copy(resp[5:11], mac)
_, err = conn.Write(resp)
return err
}
func macAddr(configuration *types.Configuration, vpnkitUUID string) (net.HardwareAddr, error) {
macStr, ok := configuration.VpnKitUUIDMacAddresses[vpnkitUUID]
if !ok {
return randomMac()
}
return net.ParseMAC(macStr)
}
func randomMac() (net.HardwareAddr, error) {
buf := make([]byte, 6)
_, err := rand.Read(buf)
if err != nil {
return nil, err
}
// Set the local bit
buf[0] |= 2
// Set the single address bit
buf[0] &= ^byte(1)
return buf, nil
}
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