ubusd.c

   1 #include <sys/socket.h>
   2 #include <sys/uio.h>
   3 #include <signal.h>
   4 #include <stdio.h>
   5 #include <unistd.h>
   6 #include <fcntl.h>
   7
   8 #include <libubox/blob.h>
   9 #include <libubox/uloop.h>
  10 #include <libubox/usock.h>
  11 #include <libubox/list.h>
  12
  13 #include "ubusd.h"
  14
  15 static struct avl_tree clients;
  16
  17 static struct ubus_msg_buf *ubus_msg_unshare(struct ubus_msg_buf *ub)
  18 {
  19         ub = realloc(ub, sizeof(*ub) + ub->len);
  20         if (!ub)
  21                 return NULL;
  22
  23         ub->refcount = 1;
  24         memcpy(ub + 1, ub->data, ub->len);
  25         ub->data = (void *) (ub + 1);
  26         return ub;
  27 }
  28
  29 struct ubus_msg_buf *ubus_msg_ref(struct ubus_msg_buf *ub)
  30 {
  31         if (ub->refcount == ~0)
  32                 return ubus_msg_unshare(ub);
  33
  34         ub->refcount++;
  35         return ub;
  36 }
  37
  38 struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared)
  39 {
  40         struct ubus_msg_buf *ub;
  41         int buflen = sizeof(*ub);
  42
  43         if (!shared)
  44                 buflen += len;
  45
  46         ub = calloc(1, buflen);
  47         if (!ub)
  48                 return NULL;
  49
  50         if (shared) {
  51                 ub->refcount = ~0;
  52                 ub->data = data;
  53         } else {
  54                 ub->refcount = 1;
  55                 ub->data = (void *) (ub + 1);
  56                 if (data)
  57                         memcpy(ub + 1, data, len);
  58         }
  59
  60         ub->len = len;
  61         return ub;
  62 }
  63
  64 void ubus_msg_free(struct ubus_msg_buf *ub)
  65 {
  66         switch (ub->refcount) {
  67         case 1:
  68         case ~0:
  69                 free(ub);
  70                 break;
  71         default:
  72                 ub->refcount--;
  73                 break;
  74         }
  75 }
  76
  77 static int ubus_msg_writev(int fd, struct ubus_msg_buf *ub, int offset)
  78 {
  79         struct iovec iov[2];
  80
  81         if (offset < sizeof(ub->hdr)) {
  82                 iov[0].iov_base = ((char *) &ub->hdr) + offset;
  83                 iov[0].iov_len = sizeof(ub->hdr) - offset;
  84                 iov[1].iov_base = (char *) ub->data;
  85                 iov[1].iov_len = ub->len;
  86                 return writev(fd, iov, 2);
  87         } else {
  88                 offset -= sizeof(ub->hdr);
  89                 return write(fd, ((char *) ub->data) + offset, ub->len - offset);
  90         }
  91 }
  92
  93 static void ubus_msg_enqueue(struct ubus_client *cl, struct ubus_msg_buf *ub)
  94 {
  95         if (cl->tx_queue[cl->txq_tail])
  96                 return;
  97
  98         cl->tx_queue[cl->txq_tail] = ub;
  99         cl->txq_tail = (cl->txq_tail + 1) % ARRAY_SIZE(cl->tx_queue);
 100 }
 101
 102 /* takes the msgbuf reference */
 103 void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 104 {
 105         int written;
 106
 107         if (!cl->tx_queue[cl->txq_cur]) {
 108                 written = ubus_msg_writev(cl->sock.fd, ub, 0);
 109                 if (written >= ub->len + sizeof(ub->hdr))
 110                         goto out;
 111
 112                 if (written < 0)
 113                         written = 0;
 114
 115                 cl->txq_ofs = written;
 116
 117                 /* get an event once we can write to the socket again */
 118                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_WRITE | ULOOP_EDGE_TRIGGER);
 119         }
 120         ubus_msg_enqueue(cl, ub);
 121
 122 out:
 123         if (free)
 124                 ubus_msg_free(ub);
 125 }
 126
 127 static struct ubus_msg_buf *ubus_msg_head(struct ubus_client *cl)
 128 {
 129         return cl->tx_queue[cl->txq_cur];
 130 }
 131
 132 static void ubus_msg_dequeue(struct ubus_client *cl)
 133 {
 134         struct ubus_msg_buf *ub = ubus_msg_head(cl);
 135
 136         if (!ub)
 137                 return;
 138
 139         ubus_msg_free(ub);
 140         cl->txq_ofs = 0;
 141         cl->tx_queue[cl->txq_cur] = NULL;
 142         cl->txq_cur = (cl->txq_cur + 1) % ARRAY_SIZE(cl->tx_queue);
 143 }
 144
 145 static void handle_client_disconnect(struct ubus_client *cl)
 146 {
 147         struct ubus_object *obj;
 148
 149         while (!list_empty(&cl->objects)) {
 150                 obj = list_first_entry(&cl->objects, struct ubus_object, list);
 151                 ubusd_free_object(obj);
 152         }
 153
 154         while (ubus_msg_head(cl))
 155                 ubus_msg_dequeue(cl);
 156
 157         ubus_free_id(&clients, &cl->id);
 158         uloop_fd_delete(&cl->sock);
 159         close(cl->sock.fd);
 160         free(cl);
 161 }
 162
 163 static void client_cb(struct uloop_fd *sock, unsigned int events)
 164 {
 165         struct ubus_client *cl = container_of(sock, struct ubus_client, sock);
 166         struct ubus_msg_buf *ub;
 167
 168         /* first try to tx more pending data */
 169         while ((ub = ubus_msg_head(cl))) {
 170                 int written;
 171
 172                 written = ubus_msg_writev(sock->fd, ub, cl->txq_ofs);
 173                 if (written < 0) {
 174                         switch(errno) {
 175                         case EINTR:
 176                         case EAGAIN:
 177                                 break;
 178                         default:
 179                                 goto disconnect;
 180                         }
 181                         break;
 182                 }
 183                 if (written == 0)
 184                         break;
 185
 186                 cl->txq_ofs += written;
 187                 if (cl->txq_ofs < ub->len + sizeof(ub->hdr))
 188                         break;
 189
 190                 ubus_msg_dequeue(cl);
 191         }
 192
 193         /* prevent further ULOOP_WRITE events if we don't have data
 194          * to send anymore */
 195         if (!ubus_msg_head(cl) && (events & ULOOP_WRITE))
 196                 uloop_fd_add(sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 197
 198 retry:
 199         if (!sock->eof && cl->pending_msg_offset < sizeof(cl->hdrbuf)) {
 200                 int offset = cl->pending_msg_offset;
 201                 int bytes;
 202
 203                 bytes = read(sock->fd, (char *)&cl->hdrbuf + offset, sizeof(cl->hdrbuf) - offset);
 204                 if (bytes < 0)
 205                         goto out;
 206
 207                 cl->pending_msg_offset += bytes;
 208                 if (cl->pending_msg_offset < sizeof(cl->hdrbuf))
 209                         goto out;
 210
 211                 if (blob_len(&cl->hdrbuf.data) + sizeof(cl->hdrbuf) > UBUS_MAX_MSGLEN)
 212                         goto disconnect;
 213
 214                 cl->pending_msg = ubus_msg_new(NULL, blob_raw_len(&cl->hdrbuf.data), false);
 215                 if (!cl->pending_msg)
 216                         goto disconnect;
 217
 218                 memcpy(&cl->pending_msg->hdr, &cl->hdrbuf.hdr, sizeof(cl->hdrbuf.hdr));
 219                 memcpy(cl->pending_msg->data, &cl->hdrbuf.data, sizeof(cl->hdrbuf.data));
 220         }
 221
 222         ub = cl->pending_msg;
 223         if (ub) {
 224                 int offset = cl->pending_msg_offset - sizeof(ub->hdr);
 225                 int len = blob_raw_len(ub->data) - offset;
 226                 int bytes = 0;
 227
 228                 if (len > 0) {
 229                         bytes = read(sock->fd, (char *) ub->data + offset, len);
 230                         if (bytes <= 0)
 231                                 goto out;
 232                 }
 233
 234                 if (bytes < len) {
 235                         cl->pending_msg_offset += bytes;
 236                         goto out;
 237                 }
 238
 239                 /* accept message */
 240                 cl->pending_msg_offset = 0;
 241                 cl->pending_msg = NULL;
 242                 ubusd_receive_message(cl, ub);
 243                 goto retry;
 244         }
 245
 246 out:
 247         if (!sock->eof || ubus_msg_head(cl))
 248                 return;
 249
 250 disconnect:
 251         handle_client_disconnect(cl);
 252 }
 253
 254 struct ubus_client *ubusd_get_client_by_id(uint32_t id)
 255 {
 256         struct ubus_id *clid;
 257
 258         clid = ubus_find_id(&clients, id);
 259         if (!clid)
 260                 return NULL;
 261
 262         return container_of(clid, struct ubus_client, id);
 263 }
 264
 265 static bool get_next_connection(int fd)
 266 {
 267         struct ubus_client *cl;
 268         int client_fd;
 269
 270         client_fd = accept(fd, NULL, 0);
 271         if (client_fd < 0) {
 272                 switch (errno) {
 273                 case ECONNABORTED:
 274                 case EINTR:
 275                         return true;
 276                 default:
 277                         return false;
 278                 }
 279         }
 280
 281         cl = calloc(1, sizeof(*cl));
 282         cl->sock.fd = client_fd;
 283
 284         INIT_LIST_HEAD(&cl->objects);
 285         if (!ubus_alloc_id(&clients, &cl->id, 0))
 286                 goto error;
 287
 288         cl->sock.cb = client_cb;
 289         uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 290         if (!ubusd_send_hello(cl))
 291                 goto error_free;
 292
 293         return true;
 294
 295 error_free:
 296         ubus_free_id(&clients, &cl->id);
 297 error:
 298         close(cl->sock.fd);
 299         free(cl);
 300         return true;
 301 }
 302
 303 static void server_cb(struct uloop_fd *fd, unsigned int events)
 304 {
 305         bool next;
 306
 307         do {
 308                 next = get_next_connection(fd->fd);
 309         } while (next);
 310 }
 311
 312 static struct uloop_fd server_fd = {
 313         .cb = server_cb,
 314 };
 315
 316 int main(int argc, char **argv)
 317 {
 318         int ret = 0;
 319
 320         signal(SIGPIPE, SIG_IGN);
 321
 322         ubus_init_id_tree(&clients);
 323
 324         uloop_init();
 325
 326         unlink(UBUS_UNIX_SOCKET);
 327         server_fd.fd = usock(USOCK_UNIX | USOCK_SERVER | USOCK_NONBLOCK, UBUS_UNIX_SOCKET, NULL);
 328         if (server_fd.fd < 0) {
 329                 perror("usock");
 330                 ret = -1;
 331                 goto out;
 332         }
 333         uloop_fd_add(&server_fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 334
 335         uloop_run();
 336
 337 out:
 338         uloop_done();
 339         return ret;
 340 }