/usr/share/gocode/src/github.com/godbus/dbus/transport_unix.go is in golang-dbus-dev 2-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 | //+build !windows
package dbus
import (
"bytes"
"encoding/binary"
"errors"
"io"
"net"
"syscall"
)
type oobReader struct {
conn *net.UnixConn
oob []byte
buf [4096]byte
}
func (o *oobReader) Read(b []byte) (n int, err error) {
n, oobn, flags, _, err := o.conn.ReadMsgUnix(b, o.buf[:])
if err != nil {
return n, err
}
if flags&syscall.MSG_CTRUNC != 0 {
return n, errors.New("dbus: control data truncated (too many fds received)")
}
o.oob = append(o.oob, o.buf[:oobn]...)
return n, nil
}
type unixTransport struct {
*net.UnixConn
hasUnixFDs bool
}
func newUnixTransport(keys string) (transport, error) {
var err error
t := new(unixTransport)
abstract := getKey(keys, "abstract")
path := getKey(keys, "path")
switch {
case abstract == "" && path == "":
return nil, errors.New("dbus: invalid address (neither path nor abstract set)")
case abstract != "" && path == "":
t.UnixConn, err = net.DialUnix("unix", nil, &net.UnixAddr{Name: "@" + abstract, Net: "unix"})
if err != nil {
return nil, err
}
return t, nil
case abstract == "" && path != "":
t.UnixConn, err = net.DialUnix("unix", nil, &net.UnixAddr{Name: path, Net: "unix"})
if err != nil {
return nil, err
}
return t, nil
default:
return nil, errors.New("dbus: invalid address (both path and abstract set)")
}
}
func init() {
transports["unix"] = newUnixTransport
}
func (t *unixTransport) EnableUnixFDs() {
t.hasUnixFDs = true
}
func (t *unixTransport) ReadMessage() (*Message, error) {
var (
blen, hlen uint32
csheader [16]byte
headers []header
order binary.ByteOrder
unixfds uint32
)
// To be sure that all bytes of out-of-band data are read, we use a special
// reader that uses ReadUnix on the underlying connection instead of Read
// and gathers the out-of-band data in a buffer.
rd := &oobReader{conn: t.UnixConn}
// read the first 16 bytes (the part of the header that has a constant size),
// from which we can figure out the length of the rest of the message
if _, err := io.ReadFull(rd, csheader[:]); err != nil {
return nil, err
}
switch csheader[0] {
case 'l':
order = binary.LittleEndian
case 'B':
order = binary.BigEndian
default:
return nil, InvalidMessageError("invalid byte order")
}
// csheader[4:8] -> length of message body, csheader[12:16] -> length of
// header fields (without alignment)
binary.Read(bytes.NewBuffer(csheader[4:8]), order, &blen)
binary.Read(bytes.NewBuffer(csheader[12:]), order, &hlen)
if hlen%8 != 0 {
hlen += 8 - (hlen % 8)
}
// decode headers and look for unix fds
headerdata := make([]byte, hlen+4)
copy(headerdata, csheader[12:])
if _, err := io.ReadFull(t, headerdata[4:]); err != nil {
return nil, err
}
dec := newDecoder(bytes.NewBuffer(headerdata), order)
dec.pos = 12
vs, err := dec.Decode(Signature{"a(yv)"})
if err != nil {
return nil, err
}
Store(vs, &headers)
for _, v := range headers {
if v.Field == byte(FieldUnixFDs) {
unixfds, _ = v.Variant.value.(uint32)
}
}
all := make([]byte, 16+hlen+blen)
copy(all, csheader[:])
copy(all[16:], headerdata[4:])
if _, err := io.ReadFull(rd, all[16+hlen:]); err != nil {
return nil, err
}
if unixfds != 0 {
if !t.hasUnixFDs {
return nil, errors.New("dbus: got unix fds on unsupported transport")
}
// read the fds from the OOB data
scms, err := syscall.ParseSocketControlMessage(rd.oob)
if err != nil {
return nil, err
}
if len(scms) != 1 {
return nil, errors.New("dbus: received more than one socket control message")
}
fds, err := syscall.ParseUnixRights(&scms[0])
if err != nil {
return nil, err
}
msg, err := DecodeMessage(bytes.NewBuffer(all))
if err != nil {
return nil, err
}
// substitute the values in the message body (which are indices for the
// array receiver via OOB) with the actual values
for i, v := range msg.Body {
if j, ok := v.(UnixFDIndex); ok {
if uint32(j) >= unixfds {
return nil, InvalidMessageError("invalid index for unix fd")
}
msg.Body[i] = UnixFD(fds[j])
}
}
return msg, nil
}
return DecodeMessage(bytes.NewBuffer(all))
}
func (t *unixTransport) SendMessage(msg *Message) error {
fds := make([]int, 0)
for i, v := range msg.Body {
if fd, ok := v.(UnixFD); ok {
msg.Body[i] = UnixFDIndex(len(fds))
fds = append(fds, int(fd))
}
}
if len(fds) != 0 {
if !t.hasUnixFDs {
return errors.New("dbus: unix fd passing not enabled")
}
msg.Headers[FieldUnixFDs] = MakeVariant(uint32(len(fds)))
oob := syscall.UnixRights(fds...)
buf := new(bytes.Buffer)
msg.EncodeTo(buf, binary.LittleEndian)
n, oobn, err := t.UnixConn.WriteMsgUnix(buf.Bytes(), oob, nil)
if err != nil {
return err
}
if n != buf.Len() || oobn != len(oob) {
return io.ErrShortWrite
}
} else {
if err := msg.EncodeTo(t, binary.LittleEndian); err != nil {
return nil
}
}
return nil
}
func (t *unixTransport) SupportsUnixFDs() bool {
return true
}
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