ubusd.c

   1 /*
   2  * Copyright (C) 2011-2014 Felix Fietkau <nbd@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <sys/socket.h>
  15 #include <sys/stat.h>
  16 #include <sys/uio.h>
  17 #ifdef FreeBSD
  18 #include <sys/param.h>
  19 #endif
  20 #include <signal.h>
  21 #include <stdio.h>
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24
  25 #include <libubox/blob.h>
  26 #include <libubox/uloop.h>
  27 #include <libubox/usock.h>
  28 #include <libubox/list.h>
  29
  30 #include "ubusd.h"
  31
  32 static struct ubus_msg_buf *ubus_msg_unshare(struct ubus_msg_buf *ub)
  33 {
  34         ub = realloc(ub, sizeof(*ub) + ub->len);
  35         if (!ub)
  36                 return NULL;
  37
  38         ub->refcount = 1;
  39         memcpy(ub + 1, ub->data, ub->len);
  40         ub->data = (void *) (ub + 1);
  41         return ub;
  42 }
  43
  44 static struct ubus_msg_buf *ubus_msg_ref(struct ubus_msg_buf *ub)
  45 {
  46         if (ub->refcount == ~0)
  47                 return ubus_msg_unshare(ub);
  48
  49         ub->refcount++;
  50         return ub;
  51 }
  52
  53 struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared)
  54 {
  55         struct ubus_msg_buf *ub;
  56         int buflen = sizeof(*ub);
  57
  58         if (!shared)
  59                 buflen += len;
  60
  61         ub = calloc(1, buflen);
  62         if (!ub)
  63                 return NULL;
  64
  65         ub->fd = -1;
  66
  67         if (shared) {
  68                 ub->refcount = ~0;
  69                 ub->data = data;
  70         } else {
  71                 ub->refcount = 1;
  72                 ub->data = (void *) (ub + 1);
  73                 if (data)
  74                         memcpy(ub + 1, data, len);
  75         }
  76
  77         ub->len = len;
  78         return ub;
  79 }
  80
  81 void ubus_msg_free(struct ubus_msg_buf *ub)
  82 {
  83         switch (ub->refcount) {
  84         case 1:
  85         case ~0:
  86                 if (ub->fd >= 0)
  87                         close(ub->fd);
  88
  89                 free(ub);
  90                 break;
  91         default:
  92                 ub->refcount--;
  93                 break;
  94         }
  95 }
  96
  97 static int ubus_msg_writev(int fd, struct ubus_msg_buf *ub, int offset)
  98 {
  99         static struct iovec iov[2];
 100         static struct {
 101                 struct cmsghdr h;
 102                 int fd;
 103         } fd_buf = {
 104                 .h = {
 105                         .cmsg_len = sizeof(fd_buf),
 106                         .cmsg_level = SOL_SOCKET,
 107                         .cmsg_type = SCM_RIGHTS,
 108                 },
 109         };
 110         struct msghdr msghdr = {
 111                 .msg_iov = iov,
 112                 .msg_iovlen = ARRAY_SIZE(iov),
 113                 .msg_control = &fd_buf,
 114                 .msg_controllen = sizeof(fd_buf),
 115         };
 116
 117         fd_buf.fd = ub->fd;
 118         if (ub->fd < 0) {
 119                 msghdr.msg_control = NULL;
 120                 msghdr.msg_controllen = 0;
 121         }
 122
 123         if (offset < sizeof(ub->hdr)) {
 124                 iov[0].iov_base = ((char *) &ub->hdr) + offset;
 125                 iov[0].iov_len = sizeof(ub->hdr) - offset;
 126                 iov[1].iov_base = (char *) ub->data;
 127                 iov[1].iov_len = ub->len;
 128
 129                 return sendmsg(fd, &msghdr, 0);
 130         } else {
 131                 offset -= sizeof(ub->hdr);
 132                 return write(fd, ((char *) ub->data) + offset, ub->len - offset);
 133         }
 134 }
 135
 136 static void ubus_msg_enqueue(struct ubus_client *cl, struct ubus_msg_buf *ub)
 137 {
 138         if (cl->tx_queue[cl->txq_tail])
 139                 return;
 140
 141         cl->tx_queue[cl->txq_tail] = ubus_msg_ref(ub);
 142         cl->txq_tail = (cl->txq_tail + 1) % ARRAY_SIZE(cl->tx_queue);
 143 }
 144
 145 /* takes the msgbuf reference */
 146 void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 147 {
 148         int written;
 149
 150         if (!cl->tx_queue[cl->txq_cur]) {
 151                 written = ubus_msg_writev(cl->sock.fd, ub, 0);
 152                 if (written >= ub->len + sizeof(ub->hdr))
 153                         goto out;
 154
 155                 if (written < 0)
 156                         written = 0;
 157
 158                 cl->txq_ofs = written;
 159
 160                 /* get an event once we can write to the socket again */
 161                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_WRITE | ULOOP_EDGE_TRIGGER);
 162         }
 163         ubus_msg_enqueue(cl, ub);
 164
 165 out:
 166         if (free)
 167                 ubus_msg_free(ub);
 168 }
 169
 170 static struct ubus_msg_buf *ubus_msg_head(struct ubus_client *cl)
 171 {
 172         return cl->tx_queue[cl->txq_cur];
 173 }
 174
 175 static void ubus_msg_dequeue(struct ubus_client *cl)
 176 {
 177         struct ubus_msg_buf *ub = ubus_msg_head(cl);
 178
 179         if (!ub)
 180                 return;
 181
 182         ubus_msg_free(ub);
 183         cl->txq_ofs = 0;
 184         cl->tx_queue[cl->txq_cur] = NULL;
 185         cl->txq_cur = (cl->txq_cur + 1) % ARRAY_SIZE(cl->tx_queue);
 186 }
 187
 188 static void handle_client_disconnect(struct ubus_client *cl)
 189 {
 190         while (ubus_msg_head(cl))
 191                 ubus_msg_dequeue(cl);
 192
 193         ubusd_proto_free_client(cl);
 194         if (cl->pending_msg_fd >= 0)
 195                 close(cl->pending_msg_fd);
 196         uloop_fd_delete(&cl->sock);
 197         close(cl->sock.fd);
 198         free(cl);
 199 }
 200
 201 static void client_cb(struct uloop_fd *sock, unsigned int events)
 202 {
 203         struct ubus_client *cl = container_of(sock, struct ubus_client, sock);
 204         struct ubus_msg_buf *ub;
 205         static struct iovec iov;
 206         static struct {
 207                 struct cmsghdr h;
 208                 int fd;
 209         } fd_buf = {
 210                 .h = {
 211                         .cmsg_type = SCM_RIGHTS,
 212                         .cmsg_level = SOL_SOCKET,
 213                         .cmsg_len = sizeof(fd_buf),
 214                 }
 215         };
 216         struct msghdr msghdr = {
 217                 .msg_iov = &iov,
 218                 .msg_iovlen = 1,
 219         };
 220
 221         /* first try to tx more pending data */
 222         while ((ub = ubus_msg_head(cl))) {
 223                 int written;
 224
 225                 written = ubus_msg_writev(sock->fd, ub, cl->txq_ofs);
 226                 if (written < 0) {
 227                         switch(errno) {
 228                         case EINTR:
 229                         case EAGAIN:
 230                                 break;
 231                         default:
 232                                 goto disconnect;
 233                         }
 234                         break;
 235                 }
 236
 237                 cl->txq_ofs += written;
 238                 if (cl->txq_ofs < ub->len + sizeof(ub->hdr))
 239                         break;
 240
 241                 ubus_msg_dequeue(cl);
 242         }
 243
 244         /* prevent further ULOOP_WRITE events if we don't have data
 245          * to send anymore */
 246         if (!ubus_msg_head(cl) && (events & ULOOP_WRITE))
 247                 uloop_fd_add(sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 248
 249 retry:
 250         if (!sock->eof && cl->pending_msg_offset < sizeof(cl->hdrbuf)) {
 251                 int offset = cl->pending_msg_offset;
 252                 int bytes;
 253
 254                 fd_buf.fd = -1;
 255
 256                 iov.iov_base = &cl->hdrbuf + offset;
 257                 iov.iov_len = sizeof(cl->hdrbuf) - offset;
 258
 259                 if (cl->pending_msg_fd < 0) {
 260                         msghdr.msg_control = &fd_buf;
 261                         msghdr.msg_controllen = sizeof(fd_buf);
 262                 } else {
 263                         msghdr.msg_control = NULL;
 264                         msghdr.msg_controllen = 0;
 265                 }
 266
 267                 bytes = recvmsg(sock->fd, &msghdr, 0);
 268                 if (bytes < 0)
 269                         goto out;
 270
 271                 if (fd_buf.fd >= 0)
 272                         cl->pending_msg_fd = fd_buf.fd;
 273
 274                 cl->pending_msg_offset += bytes;
 275                 if (cl->pending_msg_offset < sizeof(cl->hdrbuf))
 276                         goto out;
 277
 278                 if (blob_pad_len(&cl->hdrbuf.data) > UBUS_MAX_MSGLEN)
 279                         goto disconnect;
 280
 281                 cl->pending_msg = ubus_msg_new(NULL, blob_raw_len(&cl->hdrbuf.data), false);
 282                 if (!cl->pending_msg)
 283                         goto disconnect;
 284
 285                 memcpy(&cl->pending_msg->hdr, &cl->hdrbuf.hdr, sizeof(cl->hdrbuf.hdr));
 286                 memcpy(cl->pending_msg->data, &cl->hdrbuf.data, sizeof(cl->hdrbuf.data));
 287         }
 288
 289         ub = cl->pending_msg;
 290         if (ub) {
 291                 int offset = cl->pending_msg_offset - sizeof(ub->hdr);
 292                 int len = blob_raw_len(ub->data) - offset;
 293                 int bytes = 0;
 294
 295                 if (len > 0) {
 296                         bytes = read(sock->fd, (char *) ub->data + offset, len);
 297                         if (bytes <= 0)
 298                                 goto out;
 299                 }
 300
 301                 if (bytes < len) {
 302                         cl->pending_msg_offset += bytes;
 303                         goto out;
 304                 }
 305
 306                 /* accept message */
 307                 ub->fd = cl->pending_msg_fd;
 308                 cl->pending_msg_fd = -1;
 309                 cl->pending_msg_offset = 0;
 310                 cl->pending_msg = NULL;
 311                 ubusd_proto_receive_message(cl, ub);
 312                 goto retry;
 313         }
 314
 315 out:
 316         if (!sock->eof || ubus_msg_head(cl))
 317                 return;
 318
 319 disconnect:
 320         handle_client_disconnect(cl);
 321 }
 322
 323 static bool get_next_connection(int fd)
 324 {
 325         struct ubus_client *cl;
 326         int client_fd;
 327
 328         client_fd = accept(fd, NULL, 0);
 329         if (client_fd < 0) {
 330                 switch (errno) {
 331                 case ECONNABORTED:
 332                 case EINTR:
 333                         return true;
 334                 default:
 335                         return false;
 336                 }
 337         }
 338
 339         cl = ubusd_proto_new_client(client_fd, client_cb);
 340         if (cl)
 341                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 342         else
 343                 close(client_fd);
 344
 345         return true;
 346 }
 347
 348 static void server_cb(struct uloop_fd *fd, unsigned int events)
 349 {
 350         bool next;
 351
 352         do {
 353                 next = get_next_connection(fd->fd);
 354         } while (next);
 355 }
 356
 357 static struct uloop_fd server_fd = {
 358         .cb = server_cb,
 359 };
 360
 361 static int usage(const char *progname)
 362 {
 363         fprintf(stderr, "Usage: %s [<options>]\n"
 364                 "Options: \n"
 365                 "  -s <socket>:         Set the unix domain socket to listen on\n"
 366                 "\n", progname);
 367         return 1;
 368 }
 369
 370 int main(int argc, char **argv)
 371 {
 372         const char *ubus_socket = UBUS_UNIX_SOCKET;
 373         int ret = 0;
 374         int ch;
 375
 376         signal(SIGPIPE, SIG_IGN);
 377
 378         uloop_init();
 379
 380         while ((ch = getopt(argc, argv, "s:")) != -1) {
 381                 switch (ch) {
 382                 case 's':
 383                         ubus_socket = optarg;
 384                         break;
 385                 default:
 386                         return usage(argv[0]);
 387                 }
 388         }
 389
 390         unlink(ubus_socket);
 391         umask(0177);
 392         server_fd.fd = usock(USOCK_UNIX | USOCK_SERVER | USOCK_NONBLOCK, ubus_socket, NULL);
 393         if (server_fd.fd < 0) {
 394                 perror("usock");
 395                 ret = -1;
 396                 goto out;
 397         }
 398         uloop_fd_add(&server_fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 399
 400         uloop_run();
 401         unlink(ubus_socket);
 402
 403 out:
 404         uloop_done();
 405         return ret;
 406 }