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 <syslog.h>
  21 #include <signal.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25
  26 #include <libubox/blob.h>
  27 #include <libubox/uloop.h>
  28 #include <libubox/usock.h>
  29 #include <libubox/list.h>
  30
  31 #include "ubusd.h"
  32
  33 static struct ubus_msg_buf *ubus_msg_ref(struct ubus_msg_buf *ub)
  34 {
  35         if (ub->refcount == ~0)
  36                 return ubus_msg_new(ub->data, ub->len, false);
  37
  38         ub->refcount++;
  39         return ub;
  40 }
  41
  42 struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared)
  43 {
  44         struct ubus_msg_buf *ub;
  45         int buflen = sizeof(*ub);
  46
  47         if (!shared)
  48                 buflen += len;
  49
  50         ub = calloc(1, buflen);
  51         if (!ub)
  52                 return NULL;
  53
  54         ub->fd = -1;
  55
  56         if (shared) {
  57                 ub->refcount = ~0;
  58                 ub->data = data;
  59         } else {
  60                 ub->refcount = 1;
  61                 ub->data = (void *) (ub + 1);
  62                 if (data)
  63                         memcpy(ub + 1, data, len);
  64         }
  65
  66         ub->len = len;
  67         return ub;
  68 }
  69
  70 void ubus_msg_free(struct ubus_msg_buf *ub)
  71 {
  72         switch (ub->refcount) {
  73         case 1:
  74         case ~0:
  75                 if (ub->fd >= 0)
  76                         close(ub->fd);
  77
  78                 free(ub);
  79                 break;
  80         default:
  81                 ub->refcount--;
  82                 break;
  83         }
  84 }
  85
  86 static int ubus_msg_writev(int fd, struct ubus_msg_buf *ub, int offset)
  87 {
  88         static struct iovec iov[2];
  89         static struct {
  90                 struct cmsghdr h;
  91                 int fd;
  92         } fd_buf = {
  93                 .h = {
  94                         .cmsg_len = sizeof(fd_buf),
  95                         .cmsg_level = SOL_SOCKET,
  96                         .cmsg_type = SCM_RIGHTS,
  97                 },
  98         };
  99         struct msghdr msghdr = {
 100                 .msg_iov = iov,
 101                 .msg_iovlen = ARRAY_SIZE(iov),
 102                 .msg_control = &fd_buf,
 103                 .msg_controllen = sizeof(fd_buf),
 104         };
 105
 106         fd_buf.fd = ub->fd;
 107         if (ub->fd < 0) {
 108                 msghdr.msg_control = NULL;
 109                 msghdr.msg_controllen = 0;
 110         }
 111
 112         if (offset < sizeof(ub->hdr)) {
 113                 iov[0].iov_base = ((char *) &ub->hdr) + offset;
 114                 iov[0].iov_len = sizeof(ub->hdr) - offset;
 115                 iov[1].iov_base = (char *) ub->data;
 116                 iov[1].iov_len = ub->len;
 117
 118                 return sendmsg(fd, &msghdr, 0);
 119         } else {
 120                 offset -= sizeof(ub->hdr);
 121                 return write(fd, ((char *) ub->data) + offset, ub->len - offset);
 122         }
 123 }
 124
 125 static void ubus_msg_enqueue(struct ubus_client *cl, struct ubus_msg_buf *ub)
 126 {
 127         if (cl->tx_queue[cl->txq_tail])
 128                 return;
 129
 130         cl->tx_queue[cl->txq_tail] = ubus_msg_ref(ub);
 131         cl->txq_tail = (cl->txq_tail + 1) % ARRAY_SIZE(cl->tx_queue);
 132 }
 133
 134 /* takes the msgbuf reference */
 135 void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 136 {
 137         int written;
 138
 139         if (!cl->tx_queue[cl->txq_cur]) {
 140                 written = ubus_msg_writev(cl->sock.fd, ub, 0);
 141                 if (written >= ub->len + sizeof(ub->hdr))
 142                         goto out;
 143
 144                 if (written < 0)
 145                         written = 0;
 146
 147                 cl->txq_ofs = written;
 148
 149                 /* get an event once we can write to the socket again */
 150                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_WRITE | ULOOP_EDGE_TRIGGER);
 151         }
 152         ubus_msg_enqueue(cl, ub);
 153
 154 out:
 155         if (free)
 156                 ubus_msg_free(ub);
 157 }
 158
 159 static struct ubus_msg_buf *ubus_msg_head(struct ubus_client *cl)
 160 {
 161         return cl->tx_queue[cl->txq_cur];
 162 }
 163
 164 static void ubus_msg_dequeue(struct ubus_client *cl)
 165 {
 166         struct ubus_msg_buf *ub = ubus_msg_head(cl);
 167
 168         if (!ub)
 169                 return;
 170
 171         ubus_msg_free(ub);
 172         cl->txq_ofs = 0;
 173         cl->tx_queue[cl->txq_cur] = NULL;
 174         cl->txq_cur = (cl->txq_cur + 1) % ARRAY_SIZE(cl->tx_queue);
 175 }
 176
 177 static void handle_client_disconnect(struct ubus_client *cl)
 178 {
 179         while (ubus_msg_head(cl))
 180                 ubus_msg_dequeue(cl);
 181
 182         ubusd_proto_free_client(cl);
 183         if (cl->pending_msg_fd >= 0)
 184                 close(cl->pending_msg_fd);
 185         uloop_fd_delete(&cl->sock);
 186         close(cl->sock.fd);
 187         free(cl);
 188 }
 189
 190 static void client_cb(struct uloop_fd *sock, unsigned int events)
 191 {
 192         struct ubus_client *cl = container_of(sock, struct ubus_client, sock);
 193         struct ubus_msg_buf *ub;
 194         static struct iovec iov;
 195         static struct {
 196                 struct cmsghdr h;
 197                 int fd;
 198         } fd_buf = {
 199                 .h = {
 200                         .cmsg_type = SCM_RIGHTS,
 201                         .cmsg_level = SOL_SOCKET,
 202                         .cmsg_len = sizeof(fd_buf),
 203                 }
 204         };
 205         struct msghdr msghdr = {
 206                 .msg_iov = &iov,
 207                 .msg_iovlen = 1,
 208         };
 209
 210         /* first try to tx more pending data */
 211         while ((ub = ubus_msg_head(cl))) {
 212                 int written;
 213
 214                 written = ubus_msg_writev(sock->fd, ub, cl->txq_ofs);
 215                 if (written < 0) {
 216                         switch(errno) {
 217                         case EINTR:
 218                         case EAGAIN:
 219                                 break;
 220                         default:
 221                                 goto disconnect;
 222                         }
 223                         break;
 224                 }
 225
 226                 cl->txq_ofs += written;
 227                 if (cl->txq_ofs < ub->len + sizeof(ub->hdr))
 228                         break;
 229
 230                 ubus_msg_dequeue(cl);
 231         }
 232
 233         /* prevent further ULOOP_WRITE events if we don't have data
 234          * to send anymore */
 235         if (!ubus_msg_head(cl) && (events & ULOOP_WRITE))
 236                 uloop_fd_add(sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 237
 238 retry:
 239         if (!sock->eof && cl->pending_msg_offset < sizeof(cl->hdrbuf)) {
 240                 int offset = cl->pending_msg_offset;
 241                 int bytes;
 242
 243                 fd_buf.fd = -1;
 244
 245                 iov.iov_base = ((char *) &cl->hdrbuf) + offset;
 246                 iov.iov_len = sizeof(cl->hdrbuf) - offset;
 247
 248                 if (cl->pending_msg_fd < 0) {
 249                         msghdr.msg_control = &fd_buf;
 250                         msghdr.msg_controllen = sizeof(fd_buf);
 251                 } else {
 252                         msghdr.msg_control = NULL;
 253                         msghdr.msg_controllen = 0;
 254                 }
 255
 256                 bytes = recvmsg(sock->fd, &msghdr, 0);
 257                 if (bytes < 0)
 258                         goto out;
 259
 260                 if (fd_buf.fd >= 0)
 261                         cl->pending_msg_fd = fd_buf.fd;
 262
 263                 cl->pending_msg_offset += bytes;
 264                 if (cl->pending_msg_offset < sizeof(cl->hdrbuf))
 265                         goto out;
 266
 267                 if (blob_pad_len(&cl->hdrbuf.data) > UBUS_MAX_MSGLEN)
 268                         goto disconnect;
 269
 270                 cl->pending_msg = ubus_msg_new(NULL, blob_raw_len(&cl->hdrbuf.data), false);
 271                 if (!cl->pending_msg)
 272                         goto disconnect;
 273
 274                 memcpy(&cl->pending_msg->hdr, &cl->hdrbuf.hdr, sizeof(cl->hdrbuf.hdr));
 275                 memcpy(cl->pending_msg->data, &cl->hdrbuf.data, sizeof(cl->hdrbuf.data));
 276         }
 277
 278         ub = cl->pending_msg;
 279         if (ub) {
 280                 int offset = cl->pending_msg_offset - sizeof(ub->hdr);
 281                 int len = blob_raw_len(ub->data) - offset;
 282                 int bytes = 0;
 283
 284                 if (len > 0) {
 285                         bytes = read(sock->fd, (char *) ub->data + offset, len);
 286                         if (bytes <= 0)
 287                                 goto out;
 288                 }
 289
 290                 if (bytes < len) {
 291                         cl->pending_msg_offset += bytes;
 292                         goto out;
 293                 }
 294
 295                 /* accept message */
 296                 ub->fd = cl->pending_msg_fd;
 297                 cl->pending_msg_fd = -1;
 298                 cl->pending_msg_offset = 0;
 299                 cl->pending_msg = NULL;
 300                 ubusd_proto_receive_message(cl, ub);
 301                 goto retry;
 302         }
 303
 304 out:
 305         if (!sock->eof || ubus_msg_head(cl))
 306                 return;
 307
 308 disconnect:
 309         handle_client_disconnect(cl);
 310 }
 311
 312 static bool get_next_connection(int fd)
 313 {
 314         struct ubus_client *cl;
 315         int client_fd;
 316
 317         client_fd = accept(fd, NULL, 0);
 318         if (client_fd < 0) {
 319                 switch (errno) {
 320                 case ECONNABORTED:
 321                 case EINTR:
 322                         return true;
 323                 default:
 324                         return false;
 325                 }
 326         }
 327
 328         cl = ubusd_proto_new_client(client_fd, client_cb);
 329         if (cl)
 330                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 331         else
 332                 close(client_fd);
 333
 334         return true;
 335 }
 336
 337 static void server_cb(struct uloop_fd *fd, unsigned int events)
 338 {
 339         bool next;
 340
 341         do {
 342                 next = get_next_connection(fd->fd);
 343         } while (next);
 344 }
 345
 346 static struct uloop_fd server_fd = {
 347         .cb = server_cb,
 348 };
 349
 350 static int usage(const char *progname)
 351 {
 352         fprintf(stderr, "Usage: %s [<options>]\n"
 353                 "Options: \n"
 354                 "  -s <socket>:         Set the unix domain socket to listen on\n"
 355                 "\n", progname);
 356         return 1;
 357 }
 358
 359 static void sighup_handler(int sig)
 360 {
 361         ubusd_acl_load();
 362 }
 363
 364 int main(int argc, char **argv)
 365 {
 366         const char *ubus_socket = UBUS_UNIX_SOCKET;
 367         int ret = 0;
 368         int ch;
 369
 370         signal(SIGPIPE, SIG_IGN);
 371         signal(SIGHUP, sighup_handler);
 372
 373         openlog("ubusd", LOG_PID, LOG_DAEMON);
 374         uloop_init();
 375
 376         while ((ch = getopt(argc, argv, "s:")) != -1) {
 377                 switch (ch) {
 378                 case 's':
 379                         ubus_socket = optarg;
 380                         break;
 381                 default:
 382                         return usage(argv[0]);
 383                 }
 384         }
 385
 386         unlink(ubus_socket);
 387         umask(0111);
 388         server_fd.fd = usock(USOCK_UNIX | USOCK_SERVER | USOCK_NONBLOCK, ubus_socket, NULL);
 389         if (server_fd.fd < 0) {
 390                 perror("usock");
 391                 ret = -1;
 392                 goto out;
 393         }
 394         uloop_fd_add(&server_fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 395         ubusd_acl_load();
 396
 397         uloop_run();
 398         unlink(ubus_socket);
 399
 400 out:
 401         uloop_done();
 402         return ret;
 403 }