go-libvirt-plain/libvirt.go

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2016-05-20 03:05:37 +03:00
// Copyright 2016 The go-libvirt Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package libvirt is a pure Go implementation of the libvirt RPC protocol.
// For more information on the protocol, see https://libvirt.org/internals/l.html
package libvirt
import (
"bufio"
"bytes"
"errors"
"fmt"
"net"
"sync"
"github.com/davecgh/go-xdr/xdr2"
)
// ErrEventsNotSupported is returned by Events() if event streams
// are unsupported by either QEMU or libvirt.
var ErrEventsNotSupported = errors.New("event monitor is not supported")
// Libvirt implements LibVirt's remote procedure call protocol.
type Libvirt struct {
conn net.Conn
r *bufio.Reader
w *bufio.Writer
// method callbacks
cm sync.Mutex
callbacks map[uint32]chan response
// event listeners
em sync.Mutex
events map[uint32]chan *DomainEvent
// next request serial number
s uint32
}
// Domain represents a domain as seen by libvirt.
type Domain struct {
Name string
UUID [uuidSize]byte
ID int
}
// DomainEvent represents a libvirt domain event.
type DomainEvent struct {
CallbackID uint32
Domain Domain
Event string
Seconds uint64
Microseconds uint32
Padding uint8
Details []byte
}
// Connect establishes communication with the libvirt server.
// The underlying libvirt socket connection must be previously established.
func (l *Libvirt) Connect() error {
return l.connect()
}
// Disconnect shuts down communication with the libvirt server
// and closes the underlying net.Conn.
func (l *Libvirt) Disconnect() error {
// close event streams
for id := range l.events {
if err := l.removeStream(id); err != nil {
return err
}
}
// inform libvirt we're done
if err := l.disconnect(); err != nil {
return err
}
return l.conn.Close()
}
// Domains returns a list of all domains managed by libvirt.
func (l *Libvirt) Domains() ([]Domain, error) {
// these are the flags as passed by `virsh`, defined in:
// src/remote/remote_protocol.x # remote_connect_list_all_domains_args
req := struct {
NeedResults uint32
Flags uint32
}{
NeedResults: 1,
Flags: 3,
}
buf, err := encode(&req)
if err != nil {
return nil, err
}
resp, err := l.request(procConnectListAllDomains, programRemote, &buf)
if err != nil {
return nil, err
}
r := <-resp
if r.Status != StatusOK {
return nil, decodeError(r.Payload)
}
result := struct {
Domains []Domain
Count uint32
}{}
dec := xdr.NewDecoder(bytes.NewReader(r.Payload))
_, err = dec.Decode(&result)
if err != nil {
return nil, err
}
return result.Domains, nil
}
// Events streams domain events.
// If a problem is encountered setting up the event monitor connection
// an error will be returned. Errors encountered during streaming will
// cause the returned event channel to be closed.
func (l *Libvirt) Events(dom string) (<-chan DomainEvent, error) {
d, err := l.lookup(dom)
if err != nil {
return nil, err
}
payload := struct {
Padding [4]byte
Domain Domain
Event [2]byte
Flags [2]byte
}{
Padding: [4]byte{0x0, 0x0, 0x1, 0x0},
Domain: *d,
Event: [2]byte{0x0, 0x0},
Flags: [2]byte{0x0, 0x0},
}
buf, err := encode(&payload)
if err != nil {
return nil, err
}
resp, err := l.request(qemuConnectDomainMonitorEventRegister, programQEMU, &buf)
if err != nil {
return nil, err
}
res := <-resp
if res.Status != StatusOK {
err := decodeError(res.Payload)
if err == ErrUnsupported {
return nil, ErrEventsNotSupported
}
return nil, decodeError(res.Payload)
}
dec := xdr.NewDecoder(bytes.NewReader(res.Payload))
cbID, _, err := dec.DecodeUint()
if err != nil {
return nil, err
}
stream := make(chan *DomainEvent)
l.addStream(cbID, stream)
c := make(chan DomainEvent)
go func() {
// process events
for e := range stream {
c <- *e
}
}()
return c, nil
}
// Run executes the given QAPI command against a domain's QEMU instance.
// For a list of available QAPI commands, see:
// http://git.qemu.org/?p=qemu.git;a=blob;f=qapi-schema.json;hb=HEAD
func (l *Libvirt) Run(dom string, cmd []byte) ([]byte, error) {
d, err := l.lookup(dom)
if err != nil {
return nil, err
}
payload := struct {
Domain Domain
Command []byte
Flags uint32
}{
Domain: *d,
Command: cmd,
Flags: 0,
}
buf, err := encode(&payload)
if err != nil {
return nil, err
}
resp, err := l.request(qemuDomainMonitor, programQEMU, &buf)
if err != nil {
return nil, err
}
res := <-resp
if res.Status != StatusOK {
return nil, decodeError(res.Payload)
}
r := bytes.NewReader(res.Payload)
dec := xdr.NewDecoder(r)
data, _, err := dec.DecodeFixedOpaque(int32(r.Len()))
if err != nil {
return nil, err
}
// drop QMP control characters from start of line, and drop
// any trailing NULL characters from the end
return bytes.TrimRight(data[4:], "\x00"), err
}
// Version returns the version of the libvirt daemon.
func (l *Libvirt) Version() (string, error) {
resp, err := l.request(procConnectGetLibVersion, programRemote, nil)
if err != nil {
return "", err
}
r := <-resp
if r.Status != StatusOK {
return "", decodeError(r.Payload)
}
result := struct {
Version uint64
}{}
dec := xdr.NewDecoder(bytes.NewReader(r.Payload))
_, err = dec.Decode(&result)
if err != nil {
return "", err
}
// The version is provided as an int following this formula:
// version * 1,000,000 + minor * 1000 + micro
// See src/libvirt-host.c # virConnectGetLibVersion
major := result.Version / 1000000
result.Version %= 1000000
minor := result.Version / 1000
result.Version %= 1000
micro := result.Version
versionString := fmt.Sprintf("%d.%d.%d", major, minor, micro)
return versionString, nil
}
// lookup returns a domain as seen by libvirt.
func (l *Libvirt) lookup(name string) (*Domain, error) {
payload := struct {
Name string
}{name}
buf, err := encode(&payload)
if err != nil {
return nil, err
}
resp, err := l.request(procDomainLookupByName, programRemote, &buf)
if err != nil {
return nil, err
}
r := <-resp
if r.Status != StatusOK {
return nil, decodeError(r.Payload)
}
dec := xdr.NewDecoder(bytes.NewReader(r.Payload))
var d Domain
_, err = dec.Decode(&d)
if err != nil {
return nil, err
}
return &d, nil
}
// New configures a new Libvirt RPC connection.
func New(conn net.Conn) *Libvirt {
l := &Libvirt{
conn: conn,
s: 0,
r: bufio.NewReader(conn),
w: bufio.NewWriter(conn),
callbacks: make(map[uint32]chan response),
events: make(map[uint32]chan *DomainEvent),
}
go l.listen()
return l
}