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
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
use std::alloc::Layout;
use std::mem::MaybeUninit;
use std::os::unix::io::AsRawFd;
use std::str;
use libc::EINVAL;
use log::error;
use zerocopy::AsBytes;
use zerocopy::FromBytes;
use zerocopy::FromZeroes;
use zerocopy::Ref;
use super::errno_result;
use super::getpid;
use super::Error;
use super::RawDescriptor;
use super::Result;
use crate::alloc::LayoutAllocation;
use crate::descriptor::AsRawDescriptor;
use crate::descriptor::FromRawDescriptor;
use crate::descriptor::SafeDescriptor;
macro_rules! debug_pr {
($($args:tt)+) => {};
}
const NLMSGHDR_SIZE: usize = std::mem::size_of::<NlMsgHdr>();
const GENL_HDRLEN: usize = std::mem::size_of::<GenlMsgHdr>();
const NLA_HDRLEN: usize = std::mem::size_of::<NlAttr>();
const NLATTR_ALIGN_TO: usize = 4;
#[repr(C)]
#[derive(Copy, Clone, FromZeroes, FromBytes, AsBytes)]
struct NlMsgHdr {
pub nlmsg_len: u32,
pub nlmsg_type: u16,
pub nlmsg_flags: u16,
pub nlmsg_seq: u32,
pub nlmsg_pid: u32,
}
#[repr(C)]
#[derive(Copy, Clone, FromZeroes, FromBytes, AsBytes)]
pub struct NlAttr {
pub len: u16,
pub _type: u16,
}
#[repr(C)]
#[derive(Copy, Clone, FromZeroes, FromBytes, AsBytes)]
pub struct GenlMsgHdr {
pub cmd: u8,
pub version: u8,
pub reserved: u16,
}
pub struct NetlinkMessage<'a> {
pub _type: u16,
pub flags: u16,
pub seq: u32,
pub pid: u32,
pub data: &'a [u8],
}
pub struct NlAttrWithData<'a> {
pub len: u16,
pub _type: u16,
pub data: &'a [u8],
}
fn nlattr_align(offset: usize) -> usize {
(offset + NLATTR_ALIGN_TO - 1) & !(NLATTR_ALIGN_TO - 1)
}
pub struct NetlinkGenericDataIter<'a> {
data: &'a [u8],
}
impl<'a> Iterator for NetlinkGenericDataIter<'a> {
type Item = NlAttrWithData<'a>;
fn next(&mut self) -> Option<Self::Item> {
if self.data.len() < NLA_HDRLEN {
return None;
}
let nl_hdr = NlAttr::read_from(&self.data[..NLA_HDRLEN])?;
let nl_data_len = nl_hdr.len as usize;
if nl_data_len < NLA_HDRLEN || nl_data_len > self.data.len() {
return None;
}
let data_start = NLA_HDRLEN;
let data = &self.data[data_start..nl_data_len];
let next_hdr = nlattr_align(nl_data_len);
if next_hdr >= self.data.len() {
self.data = &[];
} else {
self.data = &self.data[next_hdr..];
}
Some(NlAttrWithData {
_type: nl_hdr._type,
len: nl_hdr.len,
data,
})
}
}
pub struct NetlinkMessageIter<'a> {
data: &'a [u8],
}
impl<'a> Iterator for NetlinkMessageIter<'a> {
type Item = NetlinkMessage<'a>;
fn next(&mut self) -> Option<Self::Item> {
if self.data.len() < NLMSGHDR_SIZE {
return None;
}
let hdr = NlMsgHdr::read_from(&self.data[..NLMSGHDR_SIZE])?;
let msg_len = hdr.nlmsg_len as usize;
if msg_len < NLMSGHDR_SIZE || msg_len > self.data.len() {
return None;
}
let data_start = NLMSGHDR_SIZE;
let data = &self.data[data_start..msg_len];
let align_to = std::mem::align_of::<NlMsgHdr>();
let next_hdr = (msg_len + align_to - 1) & !(align_to - 1);
if next_hdr >= self.data.len() {
self.data = &[];
} else {
self.data = &self.data[next_hdr..];
}
Some(NetlinkMessage {
_type: hdr.nlmsg_type,
flags: hdr.nlmsg_flags,
seq: hdr.nlmsg_seq,
pid: hdr.nlmsg_pid,
data,
})
}
}
pub struct NetlinkGenericSocket {
sock: SafeDescriptor,
}
impl AsRawDescriptor for NetlinkGenericSocket {
fn as_raw_descriptor(&self) -> RawDescriptor {
self.sock.as_raw_descriptor()
}
}
impl NetlinkGenericSocket {
pub fn new(nl_groups: u32) -> Result<Self> {
let sock = unsafe {
let fd = libc::socket(
libc::AF_NETLINK,
libc::SOCK_RAW | libc::SOCK_CLOEXEC,
libc::NETLINK_GENERIC,
);
if fd < 0 {
return errno_result();
}
SafeDescriptor::from_raw_descriptor(fd)
};
let mut sa = unsafe { MaybeUninit::<libc::sockaddr_nl>::zeroed().assume_init() };
sa.nl_family = libc::AF_NETLINK as libc::sa_family_t;
sa.nl_groups = nl_groups;
unsafe {
let res = libc::bind(
sock.as_raw_fd(),
&sa as *const libc::sockaddr_nl as *const libc::sockaddr,
std::mem::size_of_val(&sa) as libc::socklen_t,
);
if res < 0 {
return errno_result();
}
}
Ok(NetlinkGenericSocket { sock })
}
pub fn recv(&self) -> Result<NetlinkGenericRead> {
let buf_size = 8192; let layout = Layout::from_size_align(buf_size, std::mem::align_of::<NlMsgHdr>())
.map_err(|_| Error::new(EINVAL))?;
let allocation = LayoutAllocation::uninitialized(layout);
let bytes_read = unsafe {
let res = libc::recv(
self.sock.as_raw_fd(),
allocation.as_ptr() as *mut libc::c_void,
buf_size,
0,
);
if res < 0 {
return errno_result();
}
res as usize
};
Ok(NetlinkGenericRead {
allocation,
len: bytes_read,
})
}
pub fn family_name_query(&self, family_name: String) -> Result<NetlinkGenericRead> {
let buf_size = 1024;
debug_pr!(
"preparing query for family name {}, len {}",
family_name,
family_name.len()
);
let layout = Layout::from_size_align(buf_size, std::mem::align_of::<NlMsgHdr>())
.map_err(|_| Error::new(EINVAL))
.unwrap();
let mut allocation = LayoutAllocation::zeroed(layout);
let data = unsafe { allocation.as_mut_slice(buf_size) };
let hdr = Ref::<_, NlMsgHdr>::new(&mut data[..NLMSGHDR_SIZE])
.expect("failed to unwrap")
.into_mut();
hdr.nlmsg_len = NLMSGHDR_SIZE as u32 + GENL_HDRLEN as u32;
hdr.nlmsg_len += NLA_HDRLEN as u32 + family_name.len() as u32 + 1;
hdr.nlmsg_flags = libc::NLM_F_REQUEST as u16;
hdr.nlmsg_type = libc::GENL_ID_CTRL as u16;
hdr.nlmsg_pid = getpid() as u32;
let genl_hdr_end = NLMSGHDR_SIZE + GENL_HDRLEN;
let genl_hdr = Ref::<_, GenlMsgHdr>::new(&mut data[NLMSGHDR_SIZE..genl_hdr_end])
.expect("unable to get GenlMsgHdr from slice")
.into_mut();
genl_hdr.cmd = libc::CTRL_CMD_GETFAMILY as u8;
genl_hdr.version = 0x1;
let nlattr_start = genl_hdr_end;
let nlattr_end = nlattr_start + NLA_HDRLEN;
let nl_attr = Ref::<_, NlAttr>::new(&mut data[nlattr_start..nlattr_end])
.expect("unable to get NlAttr from slice")
.into_mut();
nl_attr._type = libc::CTRL_ATTR_FAMILY_NAME as u16;
nl_attr.len = family_name.len() as u16 + 1 + NLA_HDRLEN as u16;
let payload_start = nlattr_end;
let payload_end = payload_start + family_name.len();
data[payload_start..payload_end].copy_from_slice(family_name.as_bytes());
unsafe {
let res = libc::send(
self.sock.as_raw_fd(),
allocation.as_ptr() as *mut libc::c_void,
payload_end + 1,
0,
);
if res < 0 {
error!("failed to send get_family_cmd");
return errno_result();
}
};
match self.recv() {
Ok(msg) => Ok(msg),
Err(e) => {
error!("recv get_family returned with error {}", e);
Err(e)
}
}
}
}
fn parse_ctrl_group_name_and_id(
nested_nl_attr_data: NetlinkGenericDataIter,
group_name: &str,
) -> Option<u32> {
let mut mcast_group_id: Option<u32> = None;
for nested_nl_attr in nested_nl_attr_data {
debug_pr!(
"\t\tmcast_grp: nlattr type {}, len {}",
nested_nl_attr._type,
nested_nl_attr.len
);
if nested_nl_attr._type == libc::CTRL_ATTR_MCAST_GRP_ID as u16 {
mcast_group_id = Some(u32::from_ne_bytes(nested_nl_attr.data.try_into().unwrap()));
debug_pr!("\t\t mcast group_id {}", mcast_group_id?);
}
if nested_nl_attr._type == libc::CTRL_ATTR_MCAST_GRP_NAME as u16 {
debug_pr!(
"\t\t mcast group name {}",
strip_padding(&nested_nl_attr.data)
);
if group_name.eq(strip_padding(nested_nl_attr.data)) && mcast_group_id.is_some() {
debug_pr!(
"\t\t Got what we were looking for group_id = {} for {}",
mcast_group_id?,
group_name
);
return mcast_group_id;
}
}
}
None
}
fn parse_ctrl_mcast_group_id(
nl_attr_area: NetlinkGenericDataIter,
group_name: &str,
) -> Option<u32> {
for nested_gr_nl_attr in nl_attr_area {
debug_pr!(
"\tmcast_groups: nlattr type(gr_nr) {}, len {}",
nested_gr_nl_attr._type,
nested_gr_nl_attr.len
);
let netlink_nested_attr = NetlinkGenericDataIter {
data: nested_gr_nl_attr.data,
};
if let Some(mcast_group_id) = parse_ctrl_group_name_and_id(netlink_nested_attr, group_name)
{
return Some(mcast_group_id);
}
}
None
}
fn strip_padding(b: &[u8]) -> &str {
let pos = b
.iter()
.position(|&c| c == 0)
.expect("`b` doesn't contain any nul bytes");
str::from_utf8(&b[..pos]).unwrap()
}
pub struct NetlinkGenericRead {
allocation: LayoutAllocation,
len: usize,
}
impl NetlinkGenericRead {
pub fn iter(&self) -> NetlinkMessageIter {
let data = unsafe { &self.allocation.as_slice(self.len) };
NetlinkMessageIter { data }
}
pub fn get_multicast_group_id(&self, group_name: String) -> Option<u32> {
for netlink_msg in self.iter() {
debug_pr!(
"received type: {}, flags {}, pid {}, data {:?}",
netlink_msg._type,
netlink_msg.flags,
netlink_msg.pid,
netlink_msg.data
);
if netlink_msg._type != libc::GENL_ID_CTRL as u16 {
error!("Received not a generic netlink controller msg");
return None;
}
let netlink_data = NetlinkGenericDataIter {
data: &netlink_msg.data[GENL_HDRLEN..],
};
for nl_attr in netlink_data {
debug_pr!("nl_attr type {}, len {}", nl_attr._type, nl_attr.len);
if nl_attr._type == libc::CTRL_ATTR_MCAST_GROUPS as u16 {
let netlink_nested_attr = NetlinkGenericDataIter { data: nl_attr.data };
if let Some(mcast_group_id) =
parse_ctrl_mcast_group_id(netlink_nested_attr, &group_name)
{
return Some(mcast_group_id);
}
}
}
}
None
}
}