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