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/stat.h>
  16 #include <sys/uio.h>
  17 #include <signal.h>
  18 #include <stdio.h>
  19 #include <unistd.h>
  20 #include <fcntl.h>
  21
  22 #include <libubox/blob.h>
  23 #include <libubox/uloop.h>
  24 #include <libubox/usock.h>
  25 #include <libubox/list.h>
  26
  27 #include "ubusd.h"
  28
  29 static struct ubus_msg_buf *ubus_msg_unshare(struct ubus_msg_buf *ub)
  30 {
  31         ub = realloc(ub, sizeof(*ub) + ub->len);
  32         if (!ub)
  33                 return NULL;
  34
  35         ub->refcount = 1;
  36         memcpy(ub + 1, ub->data, ub->len);
  37         ub->data = (void *) (ub + 1);
  38         return ub;
  39 }
  40
  41 static struct ubus_msg_buf *ubus_msg_ref(struct ubus_msg_buf *ub)
  42 {
  43         if (ub->refcount == ~0)
  44                 return ubus_msg_unshare(ub);
  45
  46         ub->refcount++;
  47         return ub;
  48 }
  49
  50 struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared)
  51 {
  52         struct ubus_msg_buf *ub;
  53         int buflen = sizeof(*ub);
  54
  55         if (!shared)
  56                 buflen += len;
  57
  58         ub = calloc(1, buflen);
  59         if (!ub)
  60                 return NULL;
  61
  62         if (shared) {
  63                 ub->refcount = ~0;
  64                 ub->data = data;
  65         } else {
  66                 ub->refcount = 1;
  67                 ub->data = (void *) (ub + 1);
  68                 if (data)
  69                         memcpy(ub + 1, data, len);
  70         }
  71
  72         ub->len = len;
  73         return ub;
  74 }
  75
  76 void ubus_msg_free(struct ubus_msg_buf *ub)
  77 {
  78         switch (ub->refcount) {
  79         case 1:
  80         case ~0:
  81                 free(ub);
  82                 break;
  83         default:
  84                 ub->refcount--;
  85                 break;
  86         }
  87 }
  88
  89 static int ubus_msg_writev(int fd, struct ubus_msg_buf *ub, int offset)
  90 {
  91         struct iovec iov[2];
  92
  93         if (offset < sizeof(ub->hdr)) {
  94                 iov[0].iov_base = ((char *) &ub->hdr) + offset;
  95                 iov[0].iov_len = sizeof(ub->hdr) - offset;
  96                 iov[1].iov_base = (char *) ub->data;
  97                 iov[1].iov_len = ub->len;
  98                 return writev(fd, iov, 2);
  99         } else {
 100                 offset -= sizeof(ub->hdr);
 101                 return write(fd, ((char *) ub->data) + offset, ub->len - offset);
 102         }
 103 }
 104
 105 static void ubus_msg_enqueue(struct ubus_client *cl, struct ubus_msg_buf *ub)
 106 {
 107         if (cl->tx_queue[cl->txq_tail])
 108                 return;
 109
 110         cl->tx_queue[cl->txq_tail] = ubus_msg_ref(ub);
 111         cl->txq_tail = (cl->txq_tail + 1) % ARRAY_SIZE(cl->tx_queue);
 112 }
 113
 114 /* takes the msgbuf reference */
 115 void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 116 {
 117         int written;
 118
 119         if (!cl->tx_queue[cl->txq_cur]) {
 120                 written = ubus_msg_writev(cl->sock.fd, ub, 0);
 121                 if (written >= ub->len + sizeof(ub->hdr))
 122                         goto out;
 123
 124                 if (written < 0)
 125                         written = 0;
 126
 127                 cl->txq_ofs = written;
 128
 129                 /* get an event once we can write to the socket again */
 130                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_WRITE | ULOOP_EDGE_TRIGGER);
 131         }
 132         ubus_msg_enqueue(cl, ub);
 133
 134 out:
 135         if (free)
 136                 ubus_msg_free(ub);
 137 }
 138
 139 static struct ubus_msg_buf *ubus_msg_head(struct ubus_client *cl)
 140 {
 141         return cl->tx_queue[cl->txq_cur];
 142 }
 143
 144 static void ubus_msg_dequeue(struct ubus_client *cl)
 145 {
 146         struct ubus_msg_buf *ub = ubus_msg_head(cl);
 147
 148         if (!ub)
 149                 return;
 150
 151         ubus_msg_free(ub);
 152         cl->txq_ofs = 0;
 153         cl->tx_queue[cl->txq_cur] = NULL;
 154         cl->txq_cur = (cl->txq_cur + 1) % ARRAY_SIZE(cl->tx_queue);
 155 }
 156
 157 static void handle_client_disconnect(struct ubus_client *cl)
 158 {
 159         while (ubus_msg_head(cl))
 160                 ubus_msg_dequeue(cl);
 161
 162         ubusd_proto_free_client(cl);
 163         uloop_fd_delete(&cl->sock);
 164         close(cl->sock.fd);
 165         free(cl);
 166 }
 167
 168 static void client_cb(struct uloop_fd *sock, unsigned int events)
 169 {
 170         struct ubus_client *cl = container_of(sock, struct ubus_client, sock);
 171         struct ubus_msg_buf *ub;
 172
 173         /* first try to tx more pending data */
 174         while ((ub = ubus_msg_head(cl))) {
 175                 int written;
 176
 177                 written = ubus_msg_writev(sock->fd, ub, cl->txq_ofs);
 178                 if (written < 0) {
 179                         switch(errno) {
 180                         case EINTR:
 181                         case EAGAIN:
 182                                 break;
 183                         default:
 184                                 goto disconnect;
 185                         }
 186                         break;
 187                 }
 188
 189                 cl->txq_ofs += written;
 190                 if (cl->txq_ofs < ub->len + sizeof(ub->hdr))
 191                         break;
 192
 193                 ubus_msg_dequeue(cl);
 194         }
 195
 196         /* prevent further ULOOP_WRITE events if we don't have data
 197          * to send anymore */
 198         if (!ubus_msg_head(cl) && (events & ULOOP_WRITE))
 199                 uloop_fd_add(sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 200
 201 retry:
 202         if (!sock->eof && cl->pending_msg_offset < sizeof(cl->hdrbuf)) {
 203                 int offset = cl->pending_msg_offset;
 204                 int bytes;
 205
 206                 bytes = read(sock->fd, (char *)&cl->hdrbuf + offset, sizeof(cl->hdrbuf) - offset);
 207                 if (bytes < 0)
 208                         goto out;
 209
 210                 cl->pending_msg_offset += bytes;
 211                 if (cl->pending_msg_offset < sizeof(cl->hdrbuf))
 212                         goto out;
 213
 214                 if (blob_pad_len(&cl->hdrbuf.data) > UBUS_MAX_MSGLEN)
 215                         goto disconnect;
 216
 217                 cl->pending_msg = ubus_msg_new(NULL, blob_raw_len(&cl->hdrbuf.data), false);
 218                 if (!cl->pending_msg)
 219                         goto disconnect;
 220
 221                 memcpy(&cl->pending_msg->hdr, &cl->hdrbuf.hdr, sizeof(cl->hdrbuf.hdr));
 222                 memcpy(cl->pending_msg->data, &cl->hdrbuf.data, sizeof(cl->hdrbuf.data));
 223         }
 224
 225         ub = cl->pending_msg;
 226         if (ub) {
 227                 int offset = cl->pending_msg_offset - sizeof(ub->hdr);
 228                 int len = blob_raw_len(ub->data) - offset;
 229                 int bytes = 0;
 230
 231                 if (len > 0) {
 232                         bytes = read(sock->fd, (char *) ub->data + offset, len);
 233                         if (bytes <= 0)
 234                                 goto out;
 235                 }
 236
 237                 if (bytes < len) {
 238                         cl->pending_msg_offset += bytes;
 239                         goto out;
 240                 }
 241
 242                 /* accept message */
 243                 cl->pending_msg_offset = 0;
 244                 cl->pending_msg = NULL;
 245                 ubusd_proto_receive_message(cl, ub);
 246                 goto retry;
 247         }
 248
 249 out:
 250         if (!sock->eof || ubus_msg_head(cl))
 251                 return;
 252
 253 disconnect:
 254         handle_client_disconnect(cl);
 255 }
 256
 257 static bool get_next_connection(int fd)
 258 {
 259         struct ubus_client *cl;
 260         int client_fd;
 261
 262         client_fd = accept(fd, NULL, 0);
 263         if (client_fd < 0) {
 264                 switch (errno) {
 265                 case ECONNABORTED:
 266                 case EINTR:
 267                         return true;
 268                 default:
 269                         return false;
 270                 }
 271         }
 272
 273         cl = ubusd_proto_new_client(client_fd, client_cb);
 274         if (cl)
 275                 uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 276         else
 277                 close(client_fd);
 278
 279         return true;
 280 }
 281
 282 static void server_cb(struct uloop_fd *fd, unsigned int events)
 283 {
 284         bool next;
 285
 286         do {
 287                 next = get_next_connection(fd->fd);
 288         } while (next);
 289 }
 290
 291 static struct uloop_fd server_fd = {
 292         .cb = server_cb,
 293 };
 294
 295 static int usage(const char *progname)
 296 {
 297         fprintf(stderr, "Usage: %s [<options>]\n"
 298                 "Options: \n"
 299                 "  -s <socket>:         Set the unix domain socket to listen on\n"
 300                 "\n", progname);
 301         return 1;
 302 }
 303
 304 int main(int argc, char **argv)
 305 {
 306         const char *ubus_socket = UBUS_UNIX_SOCKET;
 307         int ret = 0;
 308         int ch;
 309
 310         signal(SIGPIPE, SIG_IGN);
 311
 312         uloop_init();
 313
 314         while ((ch = getopt(argc, argv, "s:")) != -1) {
 315                 switch (ch) {
 316                 case 's':
 317                         ubus_socket = optarg;
 318                         break;
 319                 default:
 320                         return usage(argv[0]);
 321                 }
 322         }
 323
 324         unlink(ubus_socket);
 325         umask(0177);
 326         server_fd.fd = usock(USOCK_UNIX | USOCK_SERVER | USOCK_NONBLOCK, ubus_socket, NULL);
 327         if (server_fd.fd < 0) {
 328                 perror("usock");
 329                 ret = -1;
 330                 goto out;
 331         }
 332         uloop_fd_add(&server_fd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 333
 334         uloop_run();
 335         unlink(ubus_socket);
 336
 337 out:
 338         uloop_done();
 339         return ret;
 340 }