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