/
ovs.go
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/
ovs.go
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package ovs
import (
"encoding/json"
"errors"
"fmt"
"math"
"net"
"net/http"
"strconv"
"strings"
"sync"
log "github.com/Sirupsen/logrus"
"github.com/mistifyio/mistify-agent/client"
"github.com/mistifyio/mistify-agent/rpc"
)
type (
// ovsIfaceData is a struct to help in decoding interface related output
// from ovs-vsctl
ovsIfaceData struct {
Headings []string
Data [][]string
}
// OVS is the Mistify OS subagent service
OVS struct {
bridge string
ifacePrefix string
maxIfaceNumber int
lock sync.Mutex
lastIfaceNumber int
}
)
// ovsIfaceListJSONtoNic converts the json output of an
// `ovs-vsctl list Interface` command to an array of client.Nic objects
func ovsIfaceListJSONToNic(bridge, input string) ([]*client.Nic, error) {
ifaceData := &ovsIfaceData{}
if err := json.Unmarshal([]byte(input), ifaceData); err != nil {
log.WithFields(log.Fields{
"error": err,
"input": input,
}).Error("failed to parse ovs iface json")
return nil, err
}
// Get a mapping of header name to array index
headings := make(map[string]int)
for i, colname := range ifaceData.Headings {
headings[colname] = i
}
// Assemble results
results := make([]*client.Nic, len(ifaceData.Data))
for i, row := range ifaceData.Data {
results[i] = &client.Nic{
Name: row[headings["name"]],
Device: row[headings["name"]],
Network: bridge,
Mac: row[headings["mac_in_use"]],
}
}
return results, nil
}
// cleanNic removes interface details from a nic object, leaving the externally
// configured details like bridge and IP
func cleanNic(nic client.Nic) client.Nic {
nic.Name = ""
nic.Device = ""
nic.Mac = ""
return nic
}
// ovs is a convenience wrapper for running ovs-vsctl commands
func ovs(args ...string) ([]string, error) {
cmd := command{command: "ovs-vsctl"}
return cmd.Run(append([]string{"--format", "json"}, args...)...)
}
// listOVSIfaces gets a list of interfaces attached to a bridge
func listOVSIfaces(bridge string) ([]*client.Nic, error) {
args := []string{
"list-ifaces",
bridge,
}
ifaceNames, err := ovs(args...)
if err != nil {
return nil, err
}
if len(ifaceNames) == 0 {
return []*client.Nic{}, nil
}
return getOVSIfaces(bridge, ifaceNames...)
}
// getOVSIfaces gets one or more interfaces attached to a bridge, by name
func getOVSIfaces(bridge string, ifaceNames ...string) ([]*client.Nic, error) {
args := []string{
"--columns",
"name,mac_in_use,type",
"list",
"Interface",
}
args = append(args, ifaceNames...)
results, err := ovs(args...)
if err != nil {
return nil, err
}
// The json formatting for list returns the entire result on one line
ifaceListJSON := results[0]
return ovsIfaceListJSONToNic(bridge, ifaceListJSON)
}
// addOVSIface attaches an interface to a bridge
func addOVSIface(bridge, ifaceName string, vlanTag int) error {
if vlanTag <= 0 {
vlanTag = 1
}
args := []string{
"add-port",
bridge,
ifaceName,
fmt.Sprintf("tag=%d", vlanTag),
}
_, err := ovs(args...)
return err
}
// deleteOVSIface removes an interface from a bridge
func deleteOVSIface(bridge, ifaceName string) error {
args := []string{
"del-port",
bridge,
ifaceName,
}
_, err := ovs(args...)
return err
}
// NewOVS creates a new OVS object
func NewOVS(bridge string) (*OVS, error) {
ovs := &OVS{
bridge: bridge,
ifacePrefix: "mist",
}
// 15 characters, minus the prefix and separator
// e.g. No prefix, "." sep = 10^(15-1) - 1 = 99999999999999 = 14 characters
ovs.maxIfaceNumber = int(math.Pow10(15-(len(ovs.ifacePrefix)+1)) - 1)
// Find how high the numbering has gone
ifaces, err := net.Interfaces()
if err != nil {
return nil, err
}
for _, iface := range ifaces {
parts := strings.SplitN(iface.Name, ".", 2)
if len(parts) != 2 || parts[0] != ovs.ifacePrefix {
continue
}
i, err := strconv.Atoi(parts[1])
if err != nil {
continue
}
if i > ovs.lastIfaceNumber {
ovs.lastIfaceNumber = i
}
}
return ovs, nil
}
// newIfaceName generates a new interface name
func (ovs *OVS) newIfaceName() (string, error) {
ovs.lock.Lock()
defer ovs.lock.Unlock()
initial := ovs.lastIfaceNumber
newIfaceNumber := ovs.lastIfaceNumber + 1
ifaceName := ""
for newIfaceNumber != initial {
// Too high, start back at 0
if newIfaceNumber > ovs.maxIfaceNumber {
newIfaceNumber = 0
}
ifaceName = fmt.Sprintf("%s.%d", ovs.ifacePrefix, newIfaceNumber)
// Check whether an interface with that name already exists
iface, err := net.InterfaceByName(ifaceName)
if err != nil && err.Error() != "no such network interface" {
log.WithFields(log.Fields{
"error": err,
"ifaceName": ifaceName,
}).Error("failed to look up interface by name")
return "", err
}
ovs.lastIfaceNumber = newIfaceNumber
if iface == nil {
return ifaceName, nil
}
newIfaceNumber++
}
err := errors.New("no free interface names")
log.WithFields(log.Fields{
"error": err,
"ifacePrefix": ovs.ifacePrefix,
"maxIfaceNumber": ovs.maxIfaceNumber,
}).Error("unable to generate interface name")
return "", err
}
// AddGuestInterfaces creates new interfaces for a guest
func (ovs *OVS) AddGuestInterfaces(h *http.Request, request *rpc.GuestRequest, response *rpc.GuestResponse) error {
if request.Guest == nil || request.Guest.Nics == nil {
return errors.New("missing guest with nics")
}
for i, nic := range request.Guest.Nics {
if nic.Name != "" {
continue
}
ifaceName, err := ovs.newIfaceName()
if err != nil {
return err
}
bridge := nic.Network
if bridge == "" {
bridge = ovs.bridge
}
// Create TAP interface
if err := createTAPIface(ifaceName); err != nil {
return err
}
// Add TAP interface to OVS
if err := addOVSIface(bridge, ifaceName, 0); err != nil {
// Clean up
_ = deleteTAPIface(ifaceName)
return err
}
// Populate the guest nic with new info
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
log.WithFields(log.Fields{
"error": err,
"ifaceName": ifaceName,
}).Error("failed to look up interface by name")
return err
}
request.Guest.Nics[i].Name = iface.Name
request.Guest.Nics[i].Device = iface.Name
request.Guest.Nics[i].Network = bridge
request.Guest.Nics[i].Mac = iface.HardwareAddr.String()
}
response.Guest = request.Guest
return nil
}
// RemoveGuestInterfaces removes the interfaces for a guest
func (ovs *OVS) RemoveGuestInterfaces(h *http.Request, request *rpc.GuestRequest, response *rpc.GuestResponse) error {
if request.Guest == nil || request.Guest.Nics == nil {
return errors.New("missing guest with nics")
}
for i, nic := range request.Guest.Nics {
if nic.Name == "" {
continue
}
// Remove TAP interface from OVS
if err := deleteOVSIface(nic.Network, nic.Name); err != nil {
return err
}
// Remove TAP Interface
if err := deleteTAPIface(nic.Name); err != nil {
return err
}
request.Guest.Nics[i] = cleanNic(nic)
}
response.Guest = request.Guest
return nil
}
// requestIfaceName determines the interface name from guest request information
func requestIfaceName(request *rpc.GuestRequest) (string, error) {
if request.Guest == nil || request.Guest.Id == "" {
return "", errors.New("missing guest with id")
}
return strings.Split(request.Guest.Id, "-")[4], nil
}