1 /*
2  * Copyright 6WIND S.A., 2014
3  *
4  * This work is licensed under the terms of the GNU GPL, version 2 or
5  * (at your option) any later version.  See the COPYING file in the
6  * top-level directory.
7  */
8 
9 #include <sys/types.h>
10 #include <sys/socket.h>
11 #include <sys/un.h>
12 
13 #include "qemu-common.h"
14 #include "qemu/queue.h"
15 
16 #include "ivshmem-client.h"
17 
18 /* log a message on stdout if verbose=1 */
19 #define IVSHMEM_CLIENT_DEBUG(client, fmt, ...) do { \
20         if ((client)->verbose) {         \
21             printf(fmt, ## __VA_ARGS__); \
22         }                                \
23     } while (0)
24 
25 /* read message from the unix socket */
26 static int
27 ivshmem_client_read_one_msg(IvshmemClient *client, long *index, int *fd)
28 {
29     int ret;
30     struct msghdr msg;
31     struct iovec iov[1];
32     union {
33         struct cmsghdr cmsg;
34         char control[CMSG_SPACE(sizeof(int))];
35     } msg_control;
36     struct cmsghdr *cmsg;
37 
38     iov[0].iov_base = index;
39     iov[0].iov_len = sizeof(*index);
40 
41     memset(&msg, 0, sizeof(msg));
42     msg.msg_iov = iov;
43     msg.msg_iovlen = 1;
44     msg.msg_control = &msg_control;
45     msg.msg_controllen = sizeof(msg_control);
46 
47     ret = recvmsg(client->sock_fd, &msg, 0);
48     if (ret < 0) {
49         IVSHMEM_CLIENT_DEBUG(client, "cannot read message: %s\n",
50                              strerror(errno));
51         return -1;
52     }
53     if (ret == 0) {
54         IVSHMEM_CLIENT_DEBUG(client, "lost connection to server\n");
55         return -1;
56     }
57 
58     *fd = -1;
59 
60     for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
61 
62         if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)) ||
63             cmsg->cmsg_level != SOL_SOCKET ||
64             cmsg->cmsg_type != SCM_RIGHTS) {
65             continue;
66         }
67 
68         memcpy(fd, CMSG_DATA(cmsg), sizeof(*fd));
69     }
70 
71     return 0;
72 }
73 
74 /* free a peer when the server advertises a disconnection or when the
75  * client is freed */
76 static void
77 ivshmem_client_free_peer(IvshmemClient *client, IvshmemClientPeer *peer)
78 {
79     unsigned vector;
80 
81     QTAILQ_REMOVE(&client->peer_list, peer, next);
82     for (vector = 0; vector < peer->vectors_count; vector++) {
83         close(peer->vectors[vector]);
84     }
85 
86     g_free(peer);
87 }
88 
89 /* handle message coming from server (new peer, new vectors) */
90 static int
91 ivshmem_client_handle_server_msg(IvshmemClient *client)
92 {
93     IvshmemClientPeer *peer;
94     long peer_id;
95     int ret, fd;
96 
97     ret = ivshmem_client_read_one_msg(client, &peer_id, &fd);
98     if (ret < 0) {
99         return -1;
100     }
101 
102     /* can return a peer or the local client */
103     peer = ivshmem_client_search_peer(client, peer_id);
104 
105     /* delete peer */
106     if (fd == -1) {
107 
108         if (peer == NULL || peer == &client->local) {
109             IVSHMEM_CLIENT_DEBUG(client, "receive delete for invalid "
110                                  "peer %ld\n", peer_id);
111             return -1;
112         }
113 
114         IVSHMEM_CLIENT_DEBUG(client, "delete peer id = %ld\n", peer_id);
115         ivshmem_client_free_peer(client, peer);
116         return 0;
117     }
118 
119     /* new peer */
120     if (peer == NULL) {
121         peer = g_malloc0(sizeof(*peer));
122         peer->id = peer_id;
123         peer->vectors_count = 0;
124         QTAILQ_INSERT_TAIL(&client->peer_list, peer, next);
125         IVSHMEM_CLIENT_DEBUG(client, "new peer id = %ld\n", peer_id);
126     }
127 
128     /* new vector */
129     IVSHMEM_CLIENT_DEBUG(client, "  new vector %d (fd=%d) for peer id %ld\n",
130                          peer->vectors_count, fd, peer->id);
131     peer->vectors[peer->vectors_count] = fd;
132     peer->vectors_count++;
133 
134     return 0;
135 }
136 
137 /* init a new ivshmem client */
138 int
139 ivshmem_client_init(IvshmemClient *client, const char *unix_sock_path,
140                     IvshmemClientNotifCb notif_cb, void *notif_arg,
141                     bool verbose)
142 {
143     int ret;
144     unsigned i;
145 
146     memset(client, 0, sizeof(*client));
147 
148     ret = snprintf(client->unix_sock_path, sizeof(client->unix_sock_path),
149                    "%s", unix_sock_path);
150 
151     if (ret < 0 || ret >= sizeof(client->unix_sock_path)) {
152         IVSHMEM_CLIENT_DEBUG(client, "could not copy unix socket path\n");
153         return -1;
154     }
155 
156     for (i = 0; i < IVSHMEM_CLIENT_MAX_VECTORS; i++) {
157         client->local.vectors[i] = -1;
158     }
159 
160     QTAILQ_INIT(&client->peer_list);
161     client->local.id = -1;
162 
163     client->notif_cb = notif_cb;
164     client->notif_arg = notif_arg;
165     client->verbose = verbose;
166     client->shm_fd = -1;
167     client->sock_fd = -1;
168 
169     return 0;
170 }
171 
172 /* create and connect to the unix socket */
173 int
174 ivshmem_client_connect(IvshmemClient *client)
175 {
176     struct sockaddr_un sun;
177     int fd, ret;
178     long tmp;
179 
180     IVSHMEM_CLIENT_DEBUG(client, "connect to client %s\n",
181                          client->unix_sock_path);
182 
183     client->sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
184     if (client->sock_fd < 0) {
185         IVSHMEM_CLIENT_DEBUG(client, "cannot create socket: %s\n",
186                              strerror(errno));
187         return -1;
188     }
189 
190     sun.sun_family = AF_UNIX;
191     ret = snprintf(sun.sun_path, sizeof(sun.sun_path), "%s",
192                    client->unix_sock_path);
193     if (ret < 0 || ret >= sizeof(sun.sun_path)) {
194         IVSHMEM_CLIENT_DEBUG(client, "could not copy unix socket path\n");
195         goto err_close;
196     }
197 
198     if (connect(client->sock_fd, (struct sockaddr *)&sun, sizeof(sun)) < 0) {
199         IVSHMEM_CLIENT_DEBUG(client, "cannot connect to %s: %s\n", sun.sun_path,
200                              strerror(errno));
201         goto err_close;
202     }
203 
204     /* first, we expect our index + a fd == -1 */
205     if (ivshmem_client_read_one_msg(client, &client->local.id, &fd) < 0 ||
206         client->local.id < 0 || fd != -1) {
207         IVSHMEM_CLIENT_DEBUG(client, "cannot read from server\n");
208         goto err_close;
209     }
210     IVSHMEM_CLIENT_DEBUG(client, "our_id=%ld\n", client->local.id);
211 
212     /* now, we expect shared mem fd + a -1 index, note that shm fd
213      * is not used */
214     if (ivshmem_client_read_one_msg(client, &tmp, &fd) < 0 ||
215         tmp != -1 || fd < 0) {
216         if (fd >= 0) {
217             close(fd);
218         }
219         IVSHMEM_CLIENT_DEBUG(client, "cannot read from server (2)\n");
220         goto err_close;
221     }
222     client->shm_fd = fd;
223     IVSHMEM_CLIENT_DEBUG(client, "shm_fd=%d\n", fd);
224 
225     return 0;
226 
227 err_close:
228     close(client->sock_fd);
229     client->sock_fd = -1;
230     return -1;
231 }
232 
233 /* close connection to the server, and free all peer structures */
234 void
235 ivshmem_client_close(IvshmemClient *client)
236 {
237     IvshmemClientPeer *peer;
238     unsigned i;
239 
240     IVSHMEM_CLIENT_DEBUG(client, "close client\n");
241 
242     while ((peer = QTAILQ_FIRST(&client->peer_list)) != NULL) {
243         ivshmem_client_free_peer(client, peer);
244     }
245 
246     close(client->shm_fd);
247     client->shm_fd = -1;
248     close(client->sock_fd);
249     client->sock_fd = -1;
250     client->local.id = -1;
251     for (i = 0; i < IVSHMEM_CLIENT_MAX_VECTORS; i++) {
252         close(client->local.vectors[i]);
253         client->local.vectors[i] = -1;
254     }
255     client->local.vectors_count = 0;
256 }
257 
258 /* get the fd_set according to the unix socket and peer list */
259 void
260 ivshmem_client_get_fds(const IvshmemClient *client, fd_set *fds, int *maxfd)
261 {
262     int fd;
263     unsigned vector;
264 
265     FD_SET(client->sock_fd, fds);
266     if (client->sock_fd >= *maxfd) {
267         *maxfd = client->sock_fd + 1;
268     }
269 
270     for (vector = 0; vector < client->local.vectors_count; vector++) {
271         fd = client->local.vectors[vector];
272         FD_SET(fd, fds);
273         if (fd >= *maxfd) {
274             *maxfd = fd + 1;
275         }
276     }
277 }
278 
279 /* handle events from eventfd: just print a message on notification */
280 static int
281 ivshmem_client_handle_event(IvshmemClient *client, const fd_set *cur, int maxfd)
282 {
283     IvshmemClientPeer *peer;
284     uint64_t kick;
285     unsigned i;
286     int ret;
287 
288     peer = &client->local;
289 
290     for (i = 0; i < peer->vectors_count; i++) {
291         if (peer->vectors[i] >= maxfd || !FD_ISSET(peer->vectors[i], cur)) {
292             continue;
293         }
294 
295         ret = read(peer->vectors[i], &kick, sizeof(kick));
296         if (ret < 0) {
297             return ret;
298         }
299         if (ret != sizeof(kick)) {
300             IVSHMEM_CLIENT_DEBUG(client, "invalid read size = %d\n", ret);
301             errno = EINVAL;
302             return -1;
303         }
304         IVSHMEM_CLIENT_DEBUG(client, "received event on fd %d vector %d: %"
305                              PRIu64 "\n", peer->vectors[i], i, kick);
306         if (client->notif_cb != NULL) {
307             client->notif_cb(client, peer, i, client->notif_arg);
308         }
309     }
310 
311     return 0;
312 }
313 
314 /* read and handle new messages on the given fd_set */
315 int
316 ivshmem_client_handle_fds(IvshmemClient *client, fd_set *fds, int maxfd)
317 {
318     if (client->sock_fd < maxfd && FD_ISSET(client->sock_fd, fds) &&
319         ivshmem_client_handle_server_msg(client) < 0 && errno != EINTR) {
320         IVSHMEM_CLIENT_DEBUG(client, "ivshmem_client_handle_server_msg() "
321                              "failed\n");
322         return -1;
323     } else if (ivshmem_client_handle_event(client, fds, maxfd) < 0 &&
324                errno != EINTR) {
325         IVSHMEM_CLIENT_DEBUG(client, "ivshmem_client_handle_event() failed\n");
326         return -1;
327     }
328 
329     return 0;
330 }
331 
332 /* send a notification on a vector of a peer */
333 int
334 ivshmem_client_notify(const IvshmemClient *client,
335                       const IvshmemClientPeer *peer, unsigned vector)
336 {
337     uint64_t kick;
338     int fd;
339 
340     if (vector >= peer->vectors_count) {
341         IVSHMEM_CLIENT_DEBUG(client, "invalid vector %u on peer %ld\n",
342                              vector, peer->id);
343         return -1;
344     }
345     fd = peer->vectors[vector];
346     IVSHMEM_CLIENT_DEBUG(client, "notify peer %ld on vector %d, fd %d\n",
347                          peer->id, vector, fd);
348 
349     kick = 1;
350     if (write(fd, &kick, sizeof(kick)) != sizeof(kick)) {
351         fprintf(stderr, "could not write to %d: %s\n", peer->vectors[vector],
352                 strerror(errno));
353         return -1;
354     }
355     return 0;
356 }
357 
358 /* send a notification to all vectors of a peer */
359 int
360 ivshmem_client_notify_all_vects(const IvshmemClient *client,
361                                 const IvshmemClientPeer *peer)
362 {
363     unsigned vector;
364     int ret = 0;
365 
366     for (vector = 0; vector < peer->vectors_count; vector++) {
367         if (ivshmem_client_notify(client, peer, vector) < 0) {
368             ret = -1;
369         }
370     }
371 
372     return ret;
373 }
374 
375 /* send a notification to all peers */
376 int
377 ivshmem_client_notify_broadcast(const IvshmemClient *client)
378 {
379     IvshmemClientPeer *peer;
380     int ret = 0;
381 
382     QTAILQ_FOREACH(peer, &client->peer_list, next) {
383         if (ivshmem_client_notify_all_vects(client, peer) < 0) {
384             ret = -1;
385         }
386     }
387 
388     return ret;
389 }
390 
391 /* lookup peer from its id */
392 IvshmemClientPeer *
393 ivshmem_client_search_peer(IvshmemClient *client, long peer_id)
394 {
395     IvshmemClientPeer *peer;
396 
397     if (peer_id == client->local.id) {
398         return &client->local;
399     }
400 
401     QTAILQ_FOREACH(peer, &client->peer_list, next) {
402         if (peer->id == peer_id) {
403             return peer;
404         }
405     }
406     return NULL;
407 }
408 
409 /* dump our info, the list of peers their vectors on stdout */
410 void
411 ivshmem_client_dump(const IvshmemClient *client)
412 {
413     const IvshmemClientPeer *peer;
414     unsigned vector;
415 
416     /* dump local infos */
417     peer = &client->local;
418     printf("our_id = %ld\n", peer->id);
419     for (vector = 0; vector < peer->vectors_count; vector++) {
420         printf("  vector %d is enabled (fd=%d)\n", vector,
421                peer->vectors[vector]);
422     }
423 
424     /* dump peers */
425     QTAILQ_FOREACH(peer, &client->peer_list, next) {
426         printf("peer_id = %ld\n", peer->id);
427 
428         for (vector = 0; vector < peer->vectors_count; vector++) {
429             printf("  vector %d is enabled (fd=%d)\n", vector,
430                    peer->vectors[vector]);
431         }
432     }
433 }
434