mirror of https://github.com/k3s-io/k3s
197 lines
4.9 KiB
Go
197 lines
4.9 KiB
Go
//+build !windows
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package dbus
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"io"
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"net"
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"syscall"
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)
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type oobReader struct {
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conn *net.UnixConn
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oob []byte
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buf [4096]byte
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}
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func (o *oobReader) Read(b []byte) (n int, err error) {
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n, oobn, flags, _, err := o.conn.ReadMsgUnix(b, o.buf[:])
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if err != nil {
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return n, err
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}
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if flags&syscall.MSG_CTRUNC != 0 {
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return n, errors.New("dbus: control data truncated (too many fds received)")
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}
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o.oob = append(o.oob, o.buf[:oobn]...)
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return n, nil
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}
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type unixTransport struct {
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*net.UnixConn
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hasUnixFDs bool
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}
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func newUnixTransport(keys string) (transport, error) {
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var err error
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t := new(unixTransport)
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abstract := getKey(keys, "abstract")
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path := getKey(keys, "path")
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switch {
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case abstract == "" && path == "":
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return nil, errors.New("dbus: invalid address (neither path nor abstract set)")
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case abstract != "" && path == "":
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t.UnixConn, err = net.DialUnix("unix", nil, &net.UnixAddr{Name: "@" + abstract, Net: "unix"})
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if err != nil {
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return nil, err
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}
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return t, nil
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case abstract == "" && path != "":
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t.UnixConn, err = net.DialUnix("unix", nil, &net.UnixAddr{Name: path, Net: "unix"})
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if err != nil {
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return nil, err
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}
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return t, nil
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default:
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return nil, errors.New("dbus: invalid address (both path and abstract set)")
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}
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}
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func init() {
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transports["unix"] = newUnixTransport
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}
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func (t *unixTransport) EnableUnixFDs() {
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t.hasUnixFDs = true
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}
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func (t *unixTransport) ReadMessage() (*Message, error) {
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var (
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blen, hlen uint32
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csheader [16]byte
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headers []header
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order binary.ByteOrder
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unixfds uint32
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)
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// To be sure that all bytes of out-of-band data are read, we use a special
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// reader that uses ReadUnix on the underlying connection instead of Read
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// and gathers the out-of-band data in a buffer.
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rd := &oobReader{conn: t.UnixConn}
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// read the first 16 bytes (the part of the header that has a constant size),
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// from which we can figure out the length of the rest of the message
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if _, err := io.ReadFull(rd, csheader[:]); err != nil {
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return nil, err
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}
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switch csheader[0] {
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case 'l':
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order = binary.LittleEndian
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case 'B':
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order = binary.BigEndian
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default:
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return nil, InvalidMessageError("invalid byte order")
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}
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// csheader[4:8] -> length of message body, csheader[12:16] -> length of
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// header fields (without alignment)
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binary.Read(bytes.NewBuffer(csheader[4:8]), order, &blen)
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binary.Read(bytes.NewBuffer(csheader[12:]), order, &hlen)
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if hlen%8 != 0 {
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hlen += 8 - (hlen % 8)
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}
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// decode headers and look for unix fds
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headerdata := make([]byte, hlen+4)
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copy(headerdata, csheader[12:])
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if _, err := io.ReadFull(t, headerdata[4:]); err != nil {
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return nil, err
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}
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dec := newDecoder(bytes.NewBuffer(headerdata), order)
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dec.pos = 12
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vs, err := dec.Decode(Signature{"a(yv)"})
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if err != nil {
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return nil, err
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}
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Store(vs, &headers)
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for _, v := range headers {
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if v.Field == byte(FieldUnixFDs) {
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unixfds, _ = v.Variant.value.(uint32)
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}
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}
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all := make([]byte, 16+hlen+blen)
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copy(all, csheader[:])
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copy(all[16:], headerdata[4:])
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if _, err := io.ReadFull(rd, all[16+hlen:]); err != nil {
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return nil, err
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}
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if unixfds != 0 {
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if !t.hasUnixFDs {
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return nil, errors.New("dbus: got unix fds on unsupported transport")
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}
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// read the fds from the OOB data
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scms, err := syscall.ParseSocketControlMessage(rd.oob)
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if err != nil {
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return nil, err
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}
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if len(scms) != 1 {
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return nil, errors.New("dbus: received more than one socket control message")
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}
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fds, err := syscall.ParseUnixRights(&scms[0])
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if err != nil {
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return nil, err
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}
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msg, err := DecodeMessage(bytes.NewBuffer(all))
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if err != nil {
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return nil, err
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}
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// substitute the values in the message body (which are indices for the
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// array receiver via OOB) with the actual values
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for i, v := range msg.Body {
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if j, ok := v.(UnixFDIndex); ok {
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if uint32(j) >= unixfds {
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return nil, InvalidMessageError("invalid index for unix fd")
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}
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msg.Body[i] = UnixFD(fds[j])
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}
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}
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return msg, nil
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}
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return DecodeMessage(bytes.NewBuffer(all))
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}
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func (t *unixTransport) SendMessage(msg *Message) error {
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fds := make([]int, 0)
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for i, v := range msg.Body {
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if fd, ok := v.(UnixFD); ok {
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msg.Body[i] = UnixFDIndex(len(fds))
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fds = append(fds, int(fd))
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}
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}
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if len(fds) != 0 {
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if !t.hasUnixFDs {
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return errors.New("dbus: unix fd passing not enabled")
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}
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msg.Headers[FieldUnixFDs] = MakeVariant(uint32(len(fds)))
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oob := syscall.UnixRights(fds...)
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buf := new(bytes.Buffer)
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msg.EncodeTo(buf, binary.LittleEndian)
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n, oobn, err := t.UnixConn.WriteMsgUnix(buf.Bytes(), oob, nil)
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if err != nil {
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return err
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}
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if n != buf.Len() || oobn != len(oob) {
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return io.ErrShortWrite
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}
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} else {
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if err := msg.EncodeTo(t, binary.LittleEndian); err != nil {
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return nil
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}
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}
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return nil
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}
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func (t *unixTransport) SupportsUnixFDs() bool {
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return true
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}
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