ubusd.c

   1 /*
   2  * Copyright (C) 2011 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/uio.h>
  16 #include <signal.h>
  17 #include <stdio.h>
  18 #include <unistd.h>
  19 #include <fcntl.h>
  20
  21 #include <libubox/blob.h>
  22 #include <libubox/uloop.h>
  23 #include <libubox/usock.h>
  24 #include <libubox/list.h>
  25
  26 #include "ubusd.h"
  27
  28 static struct ubus_msg_buf *ubus_msg_unshare(struct ubus_msg_buf *ub)
  29 {
  30         ub = realloc(ub, sizeof(*ub) + ub->len);
  31         if (!ub)
  32                 return NULL;
  33
  34         ub->refcount = 1;
  35         memcpy(ub + 1, ub->data, ub->len);
  36         ub->data = (void *) (ub + 1);
  37         return ub;
  38 }
  39
  40 static struct ubus_msg_buf *ubus_msg_ref(struct ubus_msg_buf *ub)
  41 {
  42         if (ub->refcount == ~0)
  43                 return ubus_msg_unshare(ub);
  44
  45         ub->refcount++;
  46         return ub;
  47 }
  48
  49 struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared)
  50 {
  51         struct ubus_msg_buf *ub;
  52         int buflen = sizeof(*ub);
  53
  54         if (!shared)
  55                 buflen += len;
  56
  57         ub = calloc(1, buflen);
  58         if (!ub)
  59                 return NULL;
  60
  61         if (shared) {
  62                 ub->refcount = ~0;
  63                 ub->data = data;
  64         } else {
  65                 ub->refcount = 1;
  66                 ub->data = (void *) (ub + 1);
  67                 if (data)
  68                         memcpy(ub + 1, data, len);
  69         }
  70
  71         ub->len = len;
  72         return ub;
  73 }
  74
  75 void ubus_msg_free(struct ubus_msg_buf *ub)
  76 {
  77         switch (ub->refcount) {
  78         case 1:
  79         case ~0:
  80                 free(ub);
  81                 break;
  82         default:
  83                 ub->refcount--;
  84                 break;
  85         }
  86 }
  87
  88 static int ubus_msg_writev(int fd, struct ubus_msg_buf *ub, int offset)
  89 {
  90         struct iovec iov[2];
  91
  92         if (offset < sizeof(ub->hdr)) {
  93                 iov[0].iov_base = ((char *) &ub->hdr) + offset;
  94                 iov[0].iov_len = sizeof(ub->hdr) - offset;
  95                 iov[1].iov_base = (char *) ub->data;
  96                 iov[1].iov_len = ub->len;
  97                 return writev(fd, iov, 2);
  98         } else {
  99                 offset -= sizeof(ub->hdr);
 100                 return write(fd, ((char *) ub->data) + offset, ub->len - offset);
 101         }
 102 }
 103
 104 static void ubus_msg_enqueue(struct ubus_client *cl, struct ubus_msg_buf *ub)
 105 {
 106         if (cl->tx_queue[cl->txq_tail])
 107                 return;
 108
 109         cl->tx_queue[cl->txq_tail] = ubus_msg_ref(ub);
 110         cl->txq_tail = (cl->txq_tail + 1) % ARRAY_SIZE(cl->tx_queue);
 111 }
 112
 113 /* takes the msgbuf reference */
 114 void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 115 {
 116         int written;
 117
 118         if (!cl->tx_queue[cl->txq_cur]) {
 119                 written = ubus_msg_writev(cl->sock.fd, ub, 0);
 120                 if (written >= ub->len + sizeof(ub->hdr))
 121                         goto out;
 122
 123                 if (written < 0)
 124                         written = 0;
 125
 126                 cl->txq_ofs = written;
 127
 128                 /* get an event once we can write to the socket again */
 129                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_WRITE | ULOOP_EDGE_TRIGGER);
 130         }
 131         ubus_msg_enqueue(cl, ub);
 132
 133 out:
 134         if (free)
 135                 ubus_msg_free(ub);
 136 }
 137
 138 static struct ubus_msg_buf *ubus_msg_head(struct ubus_client *cl)
 139 {
 140         return cl->tx_queue[cl->txq_cur];
 141 }
 142
 143 static void ubus_msg_dequeue(struct ubus_client *cl)
 144 {
 145         struct ubus_msg_buf *ub = ubus_msg_head(cl);
 146
 147         if (!ub)
 148                 return;
 149
 150         ubus_msg_free(ub);
 151         cl->txq_ofs = 0;
 152         cl->tx_queue[cl->txq_cur] = NULL;
 153         cl->txq_cur = (cl->txq_cur + 1) % ARRAY_SIZE(cl->tx_queue);
 154 }
 155
 156 static void handle_client_disconnect(struct ubus_client *cl)
 157 {
 158         while (ubus_msg_head(cl))
 159                 ubus_msg_dequeue(cl);
 160
 161         ubusd_proto_free_client(cl);
 162         uloop_fd_delete(&cl->sock);
 163         close(cl->sock.fd);
 164         free(cl);
 165 }
 166
 167 static void client_cb(struct uloop_fd *sock, unsigned int events)
 168 {
 169         struct ubus_client *cl = container_of(sock, struct ubus_client, sock);
 170         struct ubus_msg_buf *ub;
 171
 172         /* first try to tx more pending data */
 173         while ((ub = ubus_msg_head(cl))) {
 174                 int written;
 175
 176                 written = ubus_msg_writev(sock->fd, ub, cl->txq_ofs);
 177                 if (written < 0) {
 178                         switch(errno) {
 179                         case EINTR:
 180                         case EAGAIN:
 181                                 break;
 182                         default:
 183                                 goto disconnect;
 184                         }
 185                         break;
 186                 }
 187
 188                 cl->txq_ofs += written;
 189                 if (cl->txq_ofs < ub->len + sizeof(ub->hdr))
 190                         break;
 191
 192                 ubus_msg_dequeue(cl);
 193         }
 194
 195         /* prevent further ULOOP_WRITE events if we don't have data
 196          * to send anymore */
 197         if (!ubus_msg_head(cl) && (events & ULOOP_WRITE))
 198                 uloop_fd_add(sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 199
 200 retry:
 201         if (!sock->eof && cl->pending_msg_offset < sizeof(cl->hdrbuf)) {
 202                 int offset = cl->pending_msg_offset;
 203                 int bytes;
 204
 205                 bytes = read(sock->fd, (char *)&cl->hdrbuf + offset, sizeof(cl->hdrbuf) - offset);
 206                 if (bytes < 0)
 207                         goto out;
 208
 209                 cl->pending_msg_offset += bytes;
 210                 if (cl->pending_msg_offset < sizeof(cl->hdrbuf))
 211                         goto out;
 212
 213                 if (blob_pad_len(&cl->hdrbuf.data) > UBUS_MAX_MSGLEN)
 214                         goto disconnect;
 215
 216                 cl->pending_msg = ubus_msg_new(NULL, blob_raw_len(&cl->hdrbuf.data), false);
 217                 if (!cl->pending_msg)
 218                         goto disconnect;
 219
 220                 memcpy(&cl->pending_msg->hdr, &cl->hdrbuf.hdr, sizeof(cl->hdrbuf.hdr));
 221                 memcpy(cl->pending_msg->data, &cl->hdrbuf.data, sizeof(cl->hdrbuf.data));
 222         }
 223
 224         ub = cl->pending_msg;
 225         if (ub) {
 226                 int offset = cl->pending_msg_offset - sizeof(ub->hdr);
 227                 int len = blob_raw_len(ub->data) - offset;
 228                 int bytes = 0;
 229
 230                 if (len > 0) {
 231                         bytes = read(sock->fd, (char *) ub->data + offset, len);
 232                         if (bytes <= 0)
 233                                 goto out;
 234                 }
 235
 236                 if (bytes < len) {
 237                         cl->pending_msg_offset += bytes;
 238                         goto out;
 239                 }
 240
 241                 /* accept message */
 242                 cl->pending_msg_offset = 0;
 243                 cl->pending_msg = NULL;
 244                 ubusd_proto_receive_message(cl, ub);
 245                 goto retry;
 246         }
 247
 248 out:
 249         if (!sock->eof || ubus_msg_head(cl))
 250                 return;
 251
 252 disconnect:
 253         handle_client_disconnect(cl);
 254 }
 255
 256 static bool get_next_connection(int fd)
 257 {
 258         struct ubus_client *cl;
 259         int client_fd;
 260
 261         client_fd = accept(fd, NULL, 0);
 262         if (client_fd < 0) {
 263                 switch (errno) {
 264                 case ECONNABORTED:
 265                 case EINTR:
 266                         return true;
 267                 default:
 268                         return false;
 269                 }
 270         }
 271
 272         cl = ubusd_proto_new_client(client_fd, client_cb);
 273         if (cl)
 274                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 275         else
 276                 close(client_fd);
 277
 278         return true;
 279 }
 280
 281 static void server_cb(struct uloop_fd *fd, unsigned int events)
 282 {
 283         bool next;
 284
 285         do {
 286                 next = get_next_connection(fd->fd);
 287         } while (next);
 288 }
 289
 290 static struct uloop_fd server_fd = {
 291         .cb = server_cb,
 292 };
 293
 294 static int usage(const char *progname)
 295 {
 296         fprintf(stderr, "Usage: %s [<options>]\n"
 297                 "Options: \n"
 298                 "  -s <socket>:         Set the unix domain socket to listen on\n"
 299                 "\n", progname);
 300         return 1;
 301 }
 302
 303 int main(int argc, char **argv)
 304 {
 305         const char *ubus_socket = UBUS_UNIX_SOCKET;
 306         int ret = 0;
 307         int ch;
 308
 309         signal(SIGPIPE, SIG_IGN);
 310
 311         uloop_init();
 312
 313         while ((ch = getopt(argc, argv, "s:")) != -1) {
 314                 switch (ch) {
 315                 case 's':
 316                         ubus_socket = optarg;
 317                         break;
 318                 default:
 319                         return usage(argv[0]);
 320                 }
 321         }
 322
 323         unlink(ubus_socket);
 324         server_fd.fd = usock(USOCK_UNIX | USOCK_SERVER | USOCK_NONBLOCK, ubus_socket, NULL);
 325         if (server_fd.fd < 0) {
 326                 perror("usock");
 327                 ret = -1;
 328                 goto out;
 329         }
 330         uloop_fd_add(&server_fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 331
 332         uloop_run();
 333         unlink(ubus_socket);
 334
 335 out:
 336         uloop_done();
 337         return ret;
 338 }