net/tap.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  * Copyright (c) 2009 Red Hat, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "tap_int.h"
  27
  28 #include "config-host.h"
  29
  30 #include <sys/ioctl.h>
  31 #include <sys/stat.h>
  32 #include <sys/wait.h>
  33 #include <sys/socket.h>
  34 #include <net/if.h>
  35
  36 #include "net/net.h"
  37 #include "clients.h"
  38 #include "monitor/monitor.h"
  39 #include "sysemu/sysemu.h"
  40 #include "qemu-common.h"
  41 #include "qemu/error-report.h"
  42
  43 #include "net/tap.h"
  44
  45 #include "net/vhost_net.h"
  46
  47 typedef struct TAPState {
  48     NetClientState nc;
  49     int fd;
  50     char down_script[1024];
  51     char down_script_arg[128];
  52     uint8_t buf[NET_BUFSIZE];
  53     bool read_poll;
  54     bool write_poll;
  55     bool using_vnet_hdr;
  56     bool has_ufo;
  57     bool enabled;
  58     VHostNetState *vhost_net;
  59     unsigned host_vnet_hdr_len;
  60 } TAPState;
  61
  62 static int launch_script(const char *setup_script, const char *ifname, int fd);
  63
  64 static int tap_can_send(void *opaque);
  65 static void tap_send(void *opaque);
  66 static void tap_writable(void *opaque);
  67
  68 static void tap_update_fd_handler(TAPState *s)
  69 {
  70     qemu_set_fd_handler2(s->fd,
  71                          s->read_poll && s->enabled ? tap_can_send : NULL,
  72                          s->read_poll && s->enabled ? tap_send     : NULL,
  73                          s->write_poll && s->enabled ? tap_writable : NULL,
  74                          s);
  75 }
  76
  77 static void tap_read_poll(TAPState *s, bool enable)
  78 {
  79     s->read_poll = enable;
  80     tap_update_fd_handler(s);
  81 }
  82
  83 static void tap_write_poll(TAPState *s, bool enable)
  84 {
  85     s->write_poll = enable;
  86     tap_update_fd_handler(s);
  87 }
  88
  89 static void tap_writable(void *opaque)
  90 {
  91     TAPState *s = opaque;
  92
  93     tap_write_poll(s, false);
  94
  95     qemu_flush_queued_packets(&s->nc);
  96 }
  97
  98 static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
  99 {
 100     ssize_t len;
 101
 102     do {
 103         len = writev(s->fd, iov, iovcnt);
 104     } while (len == -1 && errno == EINTR);
 105
 106     if (len == -1 && errno == EAGAIN) {
 107         tap_write_poll(s, true);
 108         return 0;
 109     }
 110
 111     return len;
 112 }
 113
 114 static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov,
 115                                int iovcnt)
 116 {
 117     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 118     const struct iovec *iovp = iov;
 119     struct iovec iov_copy[iovcnt + 1];
 120     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 121
 122     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 123         iov_copy[0].iov_base = &hdr;
 124         iov_copy[0].iov_len =  s->host_vnet_hdr_len;
 125         memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
 126         iovp = iov_copy;
 127         iovcnt++;
 128     }
 129
 130     return tap_write_packet(s, iovp, iovcnt);
 131 }
 132
 133 static ssize_t tap_receive_raw(NetClientState *nc, const uint8_t *buf, size_t size)
 134 {
 135     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 136     struct iovec iov[2];
 137     int iovcnt = 0;
 138     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 139
 140     if (s->host_vnet_hdr_len) {
 141         iov[iovcnt].iov_base = &hdr;
 142         iov[iovcnt].iov_len  = s->host_vnet_hdr_len;
 143         iovcnt++;
 144     }
 145
 146     iov[iovcnt].iov_base = (char *)buf;
 147     iov[iovcnt].iov_len  = size;
 148     iovcnt++;
 149
 150     return tap_write_packet(s, iov, iovcnt);
 151 }
 152
 153 static ssize_t tap_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 154 {
 155     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 156     struct iovec iov[1];
 157
 158     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 159         return tap_receive_raw(nc, buf, size);
 160     }
 161
 162     iov[0].iov_base = (char *)buf;
 163     iov[0].iov_len  = size;
 164
 165     return tap_write_packet(s, iov, 1);
 166 }
 167
 168 static int tap_can_send(void *opaque)
 169 {
 170     TAPState *s = opaque;
 171
 172     return qemu_can_send_packet(&s->nc);
 173 }
 174
 175 #ifndef __sun__
 176 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 177 {
 178     return read(tapfd, buf, maxlen);
 179 }
 180 #endif
 181
 182 static void tap_send_completed(NetClientState *nc, ssize_t len)
 183 {
 184     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 185     tap_read_poll(s, true);
 186 }
 187
 188 static void tap_send(void *opaque)
 189 {
 190     TAPState *s = opaque;
 191     int size;
 192
 193     do {
 194         uint8_t *buf = s->buf;
 195
 196         size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
 197         if (size <= 0) {
 198             break;
 199         }
 200
 201         if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 202             buf  += s->host_vnet_hdr_len;
 203             size -= s->host_vnet_hdr_len;
 204         }
 205
 206         size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
 207         if (size == 0) {
 208             tap_read_poll(s, false);
 209         }
 210     } while (size > 0 && qemu_can_send_packet(&s->nc));
 211 }
 212
 213 bool tap_has_ufo(NetClientState *nc)
 214 {
 215     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 216
 217     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 218
 219     return s->has_ufo;
 220 }
 221
 222 int tap_has_vnet_hdr(NetClientState *nc)
 223 {
 224     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 225
 226     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 227
 228     return !!s->host_vnet_hdr_len;
 229 }
 230
 231 int tap_has_vnet_hdr_len(NetClientState *nc, int len)
 232 {
 233     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 234
 235     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 236
 237     return tap_probe_vnet_hdr_len(s->fd, len);
 238 }
 239
 240 void tap_set_vnet_hdr_len(NetClientState *nc, int len)
 241 {
 242     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 243
 244     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 245     assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
 246            len == sizeof(struct virtio_net_hdr));
 247
 248     tap_fd_set_vnet_hdr_len(s->fd, len);
 249     s->host_vnet_hdr_len = len;
 250 }
 251
 252 void tap_using_vnet_hdr(NetClientState *nc, bool using_vnet_hdr)
 253 {
 254     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 255
 256     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 257     assert(!!s->host_vnet_hdr_len == using_vnet_hdr);
 258
 259     s->using_vnet_hdr = using_vnet_hdr;
 260 }
 261
 262 void tap_set_offload(NetClientState *nc, int csum, int tso4,
 263                      int tso6, int ecn, int ufo)
 264 {
 265     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 266     if (s->fd < 0) {
 267         return;
 268     }
 269
 270     tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 271 }
 272
 273 static void tap_cleanup(NetClientState *nc)
 274 {
 275     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 276
 277     if (s->vhost_net) {
 278         vhost_net_cleanup(s->vhost_net);
 279         s->vhost_net = NULL;
 280     }
 281
 282     qemu_purge_queued_packets(nc);
 283
 284     if (s->down_script[0])
 285         launch_script(s->down_script, s->down_script_arg, s->fd);
 286
 287     tap_read_poll(s, false);
 288     tap_write_poll(s, false);
 289     close(s->fd);
 290     s->fd = -1;
 291 }
 292
 293 static void tap_poll(NetClientState *nc, bool enable)
 294 {
 295     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 296     tap_read_poll(s, enable);
 297     tap_write_poll(s, enable);
 298 }
 299
 300 int tap_get_fd(NetClientState *nc)
 301 {
 302     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 303     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 304     return s->fd;
 305 }
 306
 307 /* fd support */
 308
 309 static NetClientInfo net_tap_info = {
 310     .type = NET_CLIENT_OPTIONS_KIND_TAP,
 311     .size = sizeof(TAPState),
 312     .receive = tap_receive,
 313     .receive_raw = tap_receive_raw,
 314     .receive_iov = tap_receive_iov,
 315     .poll = tap_poll,
 316     .cleanup = tap_cleanup,
 317 };
 318
 319 static TAPState *net_tap_fd_init(NetClientState *peer,
 320                                  const char *model,
 321                                  const char *name,
 322                                  int fd,
 323                                  int vnet_hdr)
 324 {
 325     NetClientState *nc;
 326     TAPState *s;
 327
 328     nc = qemu_new_net_client(&net_tap_info, peer, model, name);
 329
 330     s = DO_UPCAST(TAPState, nc, nc);
 331
 332     s->fd = fd;
 333     s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
 334     s->using_vnet_hdr = false;
 335     s->has_ufo = tap_probe_has_ufo(s->fd);
 336     s->enabled = true;
 337     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
 338     /*
 339      * Make sure host header length is set correctly in tap:
 340      * it might have been modified by another instance of qemu.
 341      */
 342     if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) {
 343         tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len);
 344     }
 345     tap_read_poll(s, true);
 346     s->vhost_net = NULL;
 347     return s;
 348 }
 349
 350 static int launch_script(const char *setup_script, const char *ifname, int fd)
 351 {
 352     int pid, status;
 353     char *args[3];
 354     char **parg;
 355
 356     /* try to launch network script */
 357     pid = fork();
 358     if (pid == 0) {
 359         int open_max = sysconf(_SC_OPEN_MAX), i;
 360
 361         for (i = 0; i < open_max; i++) {
 362             if (i != STDIN_FILENO &&
 363                 i != STDOUT_FILENO &&
 364                 i != STDERR_FILENO &&
 365                 i != fd) {
 366                 close(i);
 367             }
 368         }
 369         parg = args;
 370         *parg++ = (char *)setup_script;
 371         *parg++ = (char *)ifname;
 372         *parg = NULL;
 373         execv(setup_script, args);
 374         _exit(1);
 375     } else if (pid > 0) {
 376         while (waitpid(pid, &status, 0) != pid) {
 377             /* loop */
 378         }
 379
 380         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 381             return 0;
 382         }
 383     }
 384     fprintf(stderr, "%s: could not launch network script\n", setup_script);
 385     return -1;
 386 }
 387
 388 static int recv_fd(int c)
 389 {
 390     int fd;
 391     uint8_t msgbuf[CMSG_SPACE(sizeof(fd))];
 392     struct msghdr msg = {
 393         .msg_control = msgbuf,
 394         .msg_controllen = sizeof(msgbuf),
 395     };
 396     struct cmsghdr *cmsg;
 397     struct iovec iov;
 398     uint8_t req[1];
 399     ssize_t len;
 400
 401     cmsg = CMSG_FIRSTHDR(&msg);
 402     cmsg->cmsg_level = SOL_SOCKET;
 403     cmsg->cmsg_type = SCM_RIGHTS;
 404     cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 405     msg.msg_controllen = cmsg->cmsg_len;
 406
 407     iov.iov_base = req;
 408     iov.iov_len = sizeof(req);
 409
 410     msg.msg_iov = &iov;
 411     msg.msg_iovlen = 1;
 412
 413     len = recvmsg(c, &msg, 0);
 414     if (len > 0) {
 415         memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
 416         return fd;
 417     }
 418
 419     return len;
 420 }
 421
 422 static int net_bridge_run_helper(const char *helper, const char *bridge)
 423 {
 424     sigset_t oldmask, mask;
 425     int pid, status;
 426     char *args[5];
 427     char **parg;
 428     int sv[2];
 429
 430     sigemptyset(&mask);
 431     sigaddset(&mask, SIGCHLD);
 432     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 433
 434     if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
 435         return -1;
 436     }
 437
 438     /* try to launch bridge helper */
 439     pid = fork();
 440     if (pid == 0) {
 441         int open_max = sysconf(_SC_OPEN_MAX), i;
 442         char fd_buf[6+10];
 443         char br_buf[6+IFNAMSIZ] = {0};
 444         char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) + 15];
 445
 446         for (i = 0; i < open_max; i++) {
 447             if (i != STDIN_FILENO &&
 448                 i != STDOUT_FILENO &&
 449                 i != STDERR_FILENO &&
 450                 i != sv[1]) {
 451                 close(i);
 452             }
 453         }
 454
 455         snprintf(fd_buf, sizeof(fd_buf), "%s%d", "--fd=", sv[1]);
 456
 457         if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
 458             /* assume helper is a command */
 459
 460             if (strstr(helper, "--br=") == NULL) {
 461                 snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
 462             }
 463
 464             snprintf(helper_cmd, sizeof(helper_cmd), "%s %s %s %s",
 465                      helper, "--use-vnet", fd_buf, br_buf);
 466
 467             parg = args;
 468             *parg++ = (char *)"sh";
 469             *parg++ = (char *)"-c";
 470             *parg++ = helper_cmd;
 471             *parg++ = NULL;
 472
 473             execv("/bin/sh", args);
 474         } else {
 475             /* assume helper is just the executable path name */
 476
 477             snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
 478
 479             parg = args;
 480             *parg++ = (char *)helper;
 481             *parg++ = (char *)"--use-vnet";
 482             *parg++ = fd_buf;
 483             *parg++ = br_buf;
 484             *parg++ = NULL;
 485
 486             execv(helper, args);
 487         }
 488         _exit(1);
 489
 490     } else if (pid > 0) {
 491         int fd;
 492
 493         close(sv[1]);
 494
 495         do {
 496             fd = recv_fd(sv[0]);
 497         } while (fd == -1 && errno == EINTR);
 498
 499         close(sv[0]);
 500
 501         while (waitpid(pid, &status, 0) != pid) {
 502             /* loop */
 503         }
 504         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 505         if (fd < 0) {
 506             fprintf(stderr, "failed to recv file descriptor\n");
 507             return -1;
 508         }
 509
 510         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 511             return fd;
 512         }
 513     }
 514     fprintf(stderr, "failed to launch bridge helper\n");
 515     return -1;
 516 }
 517
 518 int net_init_bridge(const NetClientOptions *opts, const char *name,
 519                     NetClientState *peer)
 520 {
 521     const NetdevBridgeOptions *bridge;
 522     const char *helper, *br;
 523
 524     TAPState *s;
 525     int fd, vnet_hdr;
 526
 527     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_BRIDGE);
 528     bridge = opts->bridge;
 529
 530     helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
 531     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
 532
 533     fd = net_bridge_run_helper(helper, br);
 534     if (fd == -1) {
 535         return -1;
 536     }
 537
 538     fcntl(fd, F_SETFL, O_NONBLOCK);
 539
 540     vnet_hdr = tap_probe_vnet_hdr(fd);
 541
 542     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 543     if (!s) {
 544         close(fd);
 545         return -1;
 546     }
 547
 548     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
 549              br);
 550
 551     return 0;
 552 }
 553
 554 static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
 555                         const char *setup_script, char *ifname,
 556                         size_t ifname_sz, int mq_required)
 557 {
 558     int fd, vnet_hdr_required;
 559
 560     if (tap->has_vnet_hdr) {
 561         *vnet_hdr = tap->vnet_hdr;
 562         vnet_hdr_required = *vnet_hdr;
 563     } else {
 564         *vnet_hdr = 1;
 565         vnet_hdr_required = 0;
 566     }
 567
 568     TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required,
 569                       mq_required));
 570     if (fd < 0) {
 571         return -1;
 572     }
 573
 574     if (setup_script &&
 575         setup_script[0] != '\0' &&
 576         strcmp(setup_script, "no") != 0 &&
 577         launch_script(setup_script, ifname, fd)) {
 578         close(fd);
 579         return -1;
 580     }
 581
 582     return fd;
 583 }
 584
 585 #define MAX_TAP_QUEUES 1024
 586
 587 static int net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
 588                             const char *model, const char *name,
 589                             const char *ifname, const char *script,
 590                             const char *downscript, const char *vhostfdname,
 591                             int vnet_hdr, int fd)
 592 {
 593     TAPState *s;
 594
 595     s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
 596     if (!s) {
 597         close(fd);
 598         return -1;
 599     }
 600
 601     if (tap_set_sndbuf(s->fd, tap) < 0) {
 602         return -1;
 603     }
 604
 605     if (tap->has_fd || tap->has_fds) {
 606         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
 607     } else if (tap->has_helper) {
 608         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
 609                  tap->helper);
 610     } else {
 611         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
 612                  "ifname=%s,script=%s,downscript=%s", ifname, script,
 613                  downscript);
 614
 615         if (strcmp(downscript, "no") != 0) {
 616             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
 617             snprintf(s->down_script_arg, sizeof(s->down_script_arg),
 618                      "%s", ifname);
 619         }
 620     }
 621
 622     if (tap->has_vhost ? tap->vhost :
 623         vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
 624         int vhostfd;
 625
 626         if (tap->has_vhostfd || tap->has_vhostfds) {
 627             vhostfd = monitor_handle_fd_param(cur_mon, vhostfdname);
 628             if (vhostfd == -1) {
 629                 return -1;
 630             }
 631         } else {
 632             vhostfd = -1;
 633         }
 634
 635         s->vhost_net = vhost_net_init(&s->nc, vhostfd,
 636                                       tap->has_vhostforce && tap->vhostforce);
 637         if (!s->vhost_net) {
 638             error_report("vhost-net requested but could not be initialized");
 639             return -1;
 640         }
 641     } else if (tap->has_vhostfd || tap->has_vhostfds) {
 642         error_report("vhostfd= is not valid without vhost");
 643         return -1;
 644     }
 645
 646     return 0;
 647 }
 648
 649 static int get_fds(char *str, char *fds[], int max)
 650 {
 651     char *ptr = str, *this;
 652     size_t len = strlen(str);
 653     int i = 0;
 654
 655     while (i < max && ptr < str + len) {
 656         this = strchr(ptr, ':');
 657
 658         if (this == NULL) {
 659             fds[i] = g_strdup(ptr);
 660         } else {
 661             fds[i] = g_strndup(ptr, this - ptr);
 662         }
 663
 664         i++;
 665         if (this == NULL) {
 666             break;
 667         } else {
 668             ptr = this + 1;
 669         }
 670     }
 671
 672     return i;
 673 }
 674
 675 int net_init_tap(const NetClientOptions *opts, const char *name,
 676                  NetClientState *peer)
 677 {
 678     const NetdevTapOptions *tap;
 679     int fd, vnet_hdr = 0, i = 0, queues;
 680     /* for the no-fd, no-helper case */
 681     const char *script = NULL; /* suppress wrong "uninit'd use" gcc warning */
 682     const char *downscript = NULL;
 683     const char *vhostfdname;
 684     char ifname[128];
 685
 686     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_TAP);
 687     tap = opts->tap;
 688     queues = tap->has_queues ? tap->queues : 1;
 689     vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
 690
 691     /* QEMU vlans does not support multiqueue tap, in this case peer is set.
 692      * For -netdev, peer is always NULL. */
 693     if (peer && (tap->has_queues || tap->has_fds || tap->has_vhostfds)) {
 694         error_report("Multiqueue tap cannot be used with QEMU vlans");
 695         return -1;
 696     }
 697
 698     if (tap->has_fd) {
 699         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 700             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 701             tap->has_fds || tap->has_vhostfds) {
 702             error_report("ifname=, script=, downscript=, vnet_hdr=, "
 703                          "helper=, queues=, fds=, and vhostfds= "
 704                          "are invalid with fd=");
 705             return -1;
 706         }
 707
 708         fd = monitor_handle_fd_param(cur_mon, tap->fd);
 709         if (fd == -1) {
 710             return -1;
 711         }
 712
 713         fcntl(fd, F_SETFL, O_NONBLOCK);
 714
 715         vnet_hdr = tap_probe_vnet_hdr(fd);
 716
 717         if (net_init_tap_one(tap, peer, "tap", name, NULL,
 718                              script, downscript,
 719                              vhostfdname, vnet_hdr, fd)) {
 720             return -1;
 721         }
 722     } else if (tap->has_fds) {
 723         char *fds[MAX_TAP_QUEUES];
 724         char *vhost_fds[MAX_TAP_QUEUES];
 725         int nfds, nvhosts;
 726
 727         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 728             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 729             tap->has_vhostfd) {
 730             error_report("ifname=, script=, downscript=, vnet_hdr=, "
 731                          "helper=, queues=, and vhostfd= "
 732                          "are invalid with fds=");
 733             return -1;
 734         }
 735
 736         nfds = get_fds(tap->fds, fds, MAX_TAP_QUEUES);
 737         if (tap->has_vhostfds) {
 738             nvhosts = get_fds(tap->vhostfds, vhost_fds, MAX_TAP_QUEUES);
 739             if (nfds != nvhosts) {
 740                 error_report("The number of fds passed does not match the "
 741                              "number of vhostfds passed");
 742                 return -1;
 743             }
 744         }
 745
 746         for (i = 0; i < nfds; i++) {
 747             fd = monitor_handle_fd_param(cur_mon, fds[i]);
 748             if (fd == -1) {
 749                 return -1;
 750             }
 751
 752             fcntl(fd, F_SETFL, O_NONBLOCK);
 753
 754             if (i == 0) {
 755                 vnet_hdr = tap_probe_vnet_hdr(fd);
 756             } else if (vnet_hdr != tap_probe_vnet_hdr(fd)) {
 757                 error_report("vnet_hdr not consistent across given tap fds");
 758                 return -1;
 759             }
 760
 761             if (net_init_tap_one(tap, peer, "tap", name, ifname,
 762                                  script, downscript,
 763                                  tap->has_vhostfds ? vhost_fds[i] : NULL,
 764                                  vnet_hdr, fd)) {
 765                 return -1;
 766             }
 767         }
 768     } else if (tap->has_helper) {
 769         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 770             tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
 771             error_report("ifname=, script=, downscript=, and vnet_hdr= "
 772                          "queues=, and vhostfds= are invalid with helper=");
 773             return -1;
 774         }
 775
 776         fd = net_bridge_run_helper(tap->helper, DEFAULT_BRIDGE_INTERFACE);
 777         if (fd == -1) {
 778             return -1;
 779         }
 780
 781         fcntl(fd, F_SETFL, O_NONBLOCK);
 782         vnet_hdr = tap_probe_vnet_hdr(fd);
 783
 784         if (net_init_tap_one(tap, peer, "bridge", name, ifname,
 785                              script, downscript, vhostfdname,
 786                              vnet_hdr, fd)) {
 787             return -1;
 788         }
 789     } else {
 790         if (tap->has_vhostfds) {
 791             error_report("vhostfds= is invalid if fds= wasn't specified");
 792             return -1;
 793         }
 794         script = tap->has_script ? tap->script : DEFAULT_NETWORK_SCRIPT;
 795         downscript = tap->has_downscript ? tap->downscript :
 796             DEFAULT_NETWORK_DOWN_SCRIPT;
 797
 798         if (tap->has_ifname) {
 799             pstrcpy(ifname, sizeof ifname, tap->ifname);
 800         } else {
 801             ifname[0] = '\0';
 802         }
 803
 804         for (i = 0; i < queues; i++) {
 805             fd = net_tap_init(tap, &vnet_hdr, i >= 1 ? "no" : script,
 806                               ifname, sizeof ifname, queues > 1);
 807             if (fd == -1) {
 808                 return -1;
 809             }
 810
 811             if (queues > 1 && i == 0 && !tap->has_ifname) {
 812                 if (tap_fd_get_ifname(fd, ifname)) {
 813                     error_report("Fail to get ifname");
 814                     return -1;
 815                 }
 816             }
 817
 818             if (net_init_tap_one(tap, peer, "tap", name, ifname,
 819                                  i >= 1 ? "no" : script,
 820                                  i >= 1 ? "no" : downscript,
 821                                  vhostfdname, vnet_hdr, fd)) {
 822                 return -1;
 823             }
 824         }
 825     }
 826
 827     return 0;
 828 }
 829
 830 VHostNetState *tap_get_vhost_net(NetClientState *nc)
 831 {
 832     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 833     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 834     return s->vhost_net;
 835 }
 836
 837 int tap_enable(NetClientState *nc)
 838 {
 839     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 840     int ret;
 841
 842     if (s->enabled) {
 843         return 0;
 844     } else {
 845         ret = tap_fd_enable(s->fd);
 846         if (ret == 0) {
 847             s->enabled = true;
 848             tap_update_fd_handler(s);
 849         }
 850         return ret;
 851     }
 852 }
 853
 854 int tap_disable(NetClientState *nc)
 855 {
 856     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 857     int ret;
 858
 859     if (s->enabled == 0) {
 860         return 0;
 861     } else {
 862         ret = tap_fd_disable(s->fd);
 863         if (ret == 0) {
 864             qemu_purge_queued_packets(nc);
 865             s->enabled = false;
 866             tap_update_fd_handler(s);
 867         }
 868         return ret;
 869     }
 870 }