hw/net/net_tx_pkt.c

   1 /*
   2  * QEMU TX packets abstractions
   3  *
   4  * Copyright (c) 2012 Ravello Systems LTD (http://ravellosystems.com)
   5  *
   6  * Developed by Daynix Computing LTD (http://www.daynix.com)
   7  *
   8  * Authors:
   9  * Dmitry Fleytman <dmitry@daynix.com>
  10  * Tamir Shomer <tamirs@daynix.com>
  11  * Yan Vugenfirer <yan@daynix.com>
  12  *
  13  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  14  * See the COPYING file in the top-level directory.
  15  *
  16  */
  17
  18 #include "qemu/osdep.h"
  19 #include "net_tx_pkt.h"
  20 #include "net/eth.h"
  21 #include "net/checksum.h"
  22 #include "net/tap.h"
  23 #include "net/net.h"
  24 #include "hw/pci/pci.h"
  25
  26 enum {
  27     NET_TX_PKT_VHDR_FRAG = 0,
  28     NET_TX_PKT_L2HDR_FRAG,
  29     NET_TX_PKT_L3HDR_FRAG,
  30     NET_TX_PKT_PL_START_FRAG
  31 };
  32
  33 /* TX packet private context */
  34 struct NetTxPkt {
  35     PCIDevice *pci_dev;
  36
  37     struct virtio_net_hdr virt_hdr;
  38     bool has_virt_hdr;
  39
  40     struct iovec *raw;
  41     uint32_t raw_frags;
  42     uint32_t max_raw_frags;
  43
  44     struct iovec *vec;
  45
  46     uint8_t l2_hdr[ETH_MAX_L2_HDR_LEN];
  47     uint8_t l3_hdr[ETH_MAX_IP_DGRAM_LEN];
  48
  49     uint32_t payload_len;
  50
  51     uint32_t payload_frags;
  52     uint32_t max_payload_frags;
  53
  54     uint16_t hdr_len;
  55     eth_pkt_types_e packet_type;
  56     uint8_t l4proto;
  57
  58     bool is_loopback;
  59 };
  60
  61 void net_tx_pkt_init(struct NetTxPkt **pkt, PCIDevice *pci_dev,
  62     uint32_t max_frags, bool has_virt_hdr)
  63 {
  64     struct NetTxPkt *p = g_malloc0(sizeof *p);
  65
  66     p->pci_dev = pci_dev;
  67
  68     p->vec = g_new(struct iovec, max_frags + NET_TX_PKT_PL_START_FRAG);
  69
  70     p->raw = g_new(struct iovec, max_frags);
  71
  72     p->max_payload_frags = max_frags;
  73     p->max_raw_frags = max_frags;
  74     p->has_virt_hdr = has_virt_hdr;
  75     p->vec[NET_TX_PKT_VHDR_FRAG].iov_base = &p->virt_hdr;
  76     p->vec[NET_TX_PKT_VHDR_FRAG].iov_len =
  77         p->has_virt_hdr ? sizeof p->virt_hdr : 0;
  78     p->vec[NET_TX_PKT_L2HDR_FRAG].iov_base = &p->l2_hdr;
  79     p->vec[NET_TX_PKT_L3HDR_FRAG].iov_base = &p->l3_hdr;
  80
  81     *pkt = p;
  82 }
  83
  84 void net_tx_pkt_uninit(struct NetTxPkt *pkt)
  85 {
  86     if (pkt) {
  87         g_free(pkt->vec);
  88         g_free(pkt->raw);
  89         g_free(pkt);
  90     }
  91 }
  92
  93 void net_tx_pkt_update_ip_hdr_checksum(struct NetTxPkt *pkt)
  94 {
  95     uint16_t csum;
  96     assert(pkt);
  97     struct ip_header *ip_hdr;
  98     ip_hdr = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
  99
 100     ip_hdr->ip_len = cpu_to_be16(pkt->payload_len +
 101         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len);
 102
 103     ip_hdr->ip_sum = 0;
 104     csum = net_raw_checksum((uint8_t *)ip_hdr,
 105         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len);
 106     ip_hdr->ip_sum = cpu_to_be16(csum);
 107 }
 108
 109 void net_tx_pkt_update_ip_checksums(struct NetTxPkt *pkt)
 110 {
 111     uint16_t csum;
 112     uint32_t cntr, cso;
 113     assert(pkt);
 114     uint8_t gso_type = pkt->virt_hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN;
 115     void *ip_hdr = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
 116
 117     if (pkt->payload_len + pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len >
 118         ETH_MAX_IP_DGRAM_LEN) {
 119         return;
 120     }
 121
 122     if (gso_type == VIRTIO_NET_HDR_GSO_TCPV4 ||
 123         gso_type == VIRTIO_NET_HDR_GSO_UDP) {
 124         /* Calculate IP header checksum */
 125         net_tx_pkt_update_ip_hdr_checksum(pkt);
 126
 127         /* Calculate IP pseudo header checksum */
 128         cntr = eth_calc_ip4_pseudo_hdr_csum(ip_hdr, pkt->payload_len, &cso);
 129         csum = cpu_to_be16(~net_checksum_finish(cntr));
 130     } else if (gso_type == VIRTIO_NET_HDR_GSO_TCPV6) {
 131         /* Calculate IP pseudo header checksum */
 132         cntr = eth_calc_ip6_pseudo_hdr_csum(ip_hdr, pkt->payload_len,
 133                                             IP_PROTO_TCP, &cso);
 134         csum = cpu_to_be16(~net_checksum_finish(cntr));
 135     } else {
 136         return;
 137     }
 138
 139     iov_from_buf(&pkt->vec[NET_TX_PKT_PL_START_FRAG], pkt->payload_frags,
 140                  pkt->virt_hdr.csum_offset, &csum, sizeof(csum));
 141 }
 142
 143 static void net_tx_pkt_calculate_hdr_len(struct NetTxPkt *pkt)
 144 {
 145     pkt->hdr_len = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len +
 146         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len;
 147 }
 148
 149 static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
 150 {
 151     struct iovec *l2_hdr, *l3_hdr;
 152     size_t bytes_read;
 153     size_t full_ip6hdr_len;
 154     uint16_t l3_proto;
 155
 156     assert(pkt);
 157
 158     l2_hdr = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
 159     l3_hdr = &pkt->vec[NET_TX_PKT_L3HDR_FRAG];
 160
 161     bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, 0, l2_hdr->iov_base,
 162                             ETH_MAX_L2_HDR_LEN);
 163     if (bytes_read < sizeof(struct eth_header)) {
 164         l2_hdr->iov_len = 0;
 165         return false;
 166     }
 167
 168     l2_hdr->iov_len = sizeof(struct eth_header);
 169     switch (be16_to_cpu(PKT_GET_ETH_HDR(l2_hdr->iov_base)->h_proto)) {
 170     case ETH_P_VLAN:
 171         l2_hdr->iov_len += sizeof(struct vlan_header);
 172         break;
 173     case ETH_P_DVLAN:
 174         l2_hdr->iov_len += 2 * sizeof(struct vlan_header);
 175         break;
 176     }
 177
 178     if (bytes_read < l2_hdr->iov_len) {
 179         l2_hdr->iov_len = 0;
 180         l3_hdr->iov_len = 0;
 181         pkt->packet_type = ETH_PKT_UCAST;
 182         return false;
 183     } else {
 184         l2_hdr->iov_len = ETH_MAX_L2_HDR_LEN;
 185         l2_hdr->iov_len = eth_get_l2_hdr_length(l2_hdr->iov_base);
 186         pkt->packet_type = get_eth_packet_type(l2_hdr->iov_base);
 187     }
 188
 189     l3_proto = eth_get_l3_proto(l2_hdr, 1, l2_hdr->iov_len);
 190
 191     switch (l3_proto) {
 192     case ETH_P_IP:
 193         bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
 194                                 l3_hdr->iov_base, sizeof(struct ip_header));
 195
 196         if (bytes_read < sizeof(struct ip_header)) {
 197             l3_hdr->iov_len = 0;
 198             return false;
 199         }
 200
 201         l3_hdr->iov_len = IP_HDR_GET_LEN(l3_hdr->iov_base);
 202
 203         if (l3_hdr->iov_len < sizeof(struct ip_header)) {
 204             l3_hdr->iov_len = 0;
 205             return false;
 206         }
 207
 208         pkt->l4proto = IP_HDR_GET_P(l3_hdr->iov_base);
 209
 210         if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
 211             /* copy optional IPv4 header data if any*/
 212             bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags,
 213                                     l2_hdr->iov_len + sizeof(struct ip_header),
 214                                     l3_hdr->iov_base + sizeof(struct ip_header),
 215                                     l3_hdr->iov_len - sizeof(struct ip_header));
 216             if (bytes_read < l3_hdr->iov_len - sizeof(struct ip_header)) {
 217                 l3_hdr->iov_len = 0;
 218                 return false;
 219             }
 220         }
 221
 222         break;
 223
 224     case ETH_P_IPV6:
 225     {
 226         eth_ip6_hdr_info hdrinfo;
 227
 228         if (!eth_parse_ipv6_hdr(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
 229                                 &hdrinfo)) {
 230             l3_hdr->iov_len = 0;
 231             return false;
 232         }
 233
 234         pkt->l4proto = hdrinfo.l4proto;
 235         full_ip6hdr_len = hdrinfo.full_hdr_len;
 236
 237         if (full_ip6hdr_len > ETH_MAX_IP_DGRAM_LEN) {
 238             l3_hdr->iov_len = 0;
 239             return false;
 240         }
 241
 242         bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
 243                                 l3_hdr->iov_base, full_ip6hdr_len);
 244
 245         if (bytes_read < full_ip6hdr_len) {
 246             l3_hdr->iov_len = 0;
 247             return false;
 248         } else {
 249             l3_hdr->iov_len = full_ip6hdr_len;
 250         }
 251         break;
 252     }
 253     default:
 254         l3_hdr->iov_len = 0;
 255         break;
 256     }
 257
 258     net_tx_pkt_calculate_hdr_len(pkt);
 259     return true;
 260 }
 261
 262 static void net_tx_pkt_rebuild_payload(struct NetTxPkt *pkt)
 263 {
 264     pkt->payload_len = iov_size(pkt->raw, pkt->raw_frags) - pkt->hdr_len;
 265     pkt->payload_frags = iov_copy(&pkt->vec[NET_TX_PKT_PL_START_FRAG],
 266                                 pkt->max_payload_frags,
 267                                 pkt->raw, pkt->raw_frags,
 268                                 pkt->hdr_len, pkt->payload_len);
 269 }
 270
 271 bool net_tx_pkt_parse(struct NetTxPkt *pkt)
 272 {
 273     if (net_tx_pkt_parse_headers(pkt)) {
 274         net_tx_pkt_rebuild_payload(pkt);
 275         return true;
 276     } else {
 277         return false;
 278     }
 279 }
 280
 281 struct virtio_net_hdr *net_tx_pkt_get_vhdr(struct NetTxPkt *pkt)
 282 {
 283     assert(pkt);
 284     return &pkt->virt_hdr;
 285 }
 286
 287 static uint8_t net_tx_pkt_get_gso_type(struct NetTxPkt *pkt,
 288                                           bool tso_enable)
 289 {
 290     uint8_t rc = VIRTIO_NET_HDR_GSO_NONE;
 291     uint16_t l3_proto;
 292
 293     l3_proto = eth_get_l3_proto(&pkt->vec[NET_TX_PKT_L2HDR_FRAG], 1,
 294         pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len);
 295
 296     if (!tso_enable) {
 297         goto func_exit;
 298     }
 299
 300     rc = eth_get_gso_type(l3_proto, pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base,
 301                           pkt->l4proto);
 302
 303 func_exit:
 304     return rc;
 305 }
 306
 307 void net_tx_pkt_build_vheader(struct NetTxPkt *pkt, bool tso_enable,
 308     bool csum_enable, uint32_t gso_size)
 309 {
 310     struct tcp_hdr l4hdr;
 311     assert(pkt);
 312
 313     /* csum has to be enabled if tso is. */
 314     assert(csum_enable || !tso_enable);
 315
 316     pkt->virt_hdr.gso_type = net_tx_pkt_get_gso_type(pkt, tso_enable);
 317
 318     switch (pkt->virt_hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 319     case VIRTIO_NET_HDR_GSO_NONE:
 320         pkt->virt_hdr.hdr_len = 0;
 321         pkt->virt_hdr.gso_size = 0;
 322         break;
 323
 324     case VIRTIO_NET_HDR_GSO_UDP:
 325         pkt->virt_hdr.gso_size = gso_size;
 326         pkt->virt_hdr.hdr_len = pkt->hdr_len + sizeof(struct udp_header);
 327         break;
 328
 329     case VIRTIO_NET_HDR_GSO_TCPV4:
 330     case VIRTIO_NET_HDR_GSO_TCPV6:
 331         iov_to_buf(&pkt->vec[NET_TX_PKT_PL_START_FRAG], pkt->payload_frags,
 332                    0, &l4hdr, sizeof(l4hdr));
 333         pkt->virt_hdr.hdr_len = pkt->hdr_len + l4hdr.th_off * sizeof(uint32_t);
 334         pkt->virt_hdr.gso_size = gso_size;
 335         break;
 336
 337     default:
 338         g_assert_not_reached();
 339     }
 340
 341     if (csum_enable) {
 342         switch (pkt->l4proto) {
 343         case IP_PROTO_TCP:
 344             pkt->virt_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 345             pkt->virt_hdr.csum_start = pkt->hdr_len;
 346             pkt->virt_hdr.csum_offset = offsetof(struct tcp_hdr, th_sum);
 347             break;
 348         case IP_PROTO_UDP:
 349             pkt->virt_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 350             pkt->virt_hdr.csum_start = pkt->hdr_len;
 351             pkt->virt_hdr.csum_offset = offsetof(struct udp_hdr, uh_sum);
 352             break;
 353         default:
 354             break;
 355         }
 356     }
 357 }
 358
 359 void net_tx_pkt_setup_vlan_header_ex(struct NetTxPkt *pkt,
 360     uint16_t vlan, uint16_t vlan_ethtype)
 361 {
 362     bool is_new;
 363     assert(pkt);
 364
 365     eth_setup_vlan_headers_ex(pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base,
 366         vlan, vlan_ethtype, &is_new);
 367
 368     /* update l2hdrlen */
 369     if (is_new) {
 370         pkt->hdr_len += sizeof(struct vlan_header);
 371         pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len +=
 372             sizeof(struct vlan_header);
 373     }
 374 }
 375
 376 bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, hwaddr pa,
 377     size_t len)
 378 {
 379     hwaddr mapped_len = 0;
 380     struct iovec *ventry;
 381     assert(pkt);
 382
 383     if (pkt->raw_frags >= pkt->max_raw_frags) {
 384         return false;
 385     }
 386
 387     if (!len) {
 388         return true;
 389      }
 390
 391     ventry = &pkt->raw[pkt->raw_frags];
 392     mapped_len = len;
 393
 394     ventry->iov_base = pci_dma_map(pkt->pci_dev, pa,
 395                                    &mapped_len, DMA_DIRECTION_TO_DEVICE);
 396
 397     if ((ventry->iov_base != NULL) && (len == mapped_len)) {
 398         ventry->iov_len = mapped_len;
 399         pkt->raw_frags++;
 400         return true;
 401     } else {
 402         return false;
 403     }
 404 }
 405
 406 bool net_tx_pkt_has_fragments(struct NetTxPkt *pkt)
 407 {
 408     return pkt->raw_frags > 0;
 409 }
 410
 411 eth_pkt_types_e net_tx_pkt_get_packet_type(struct NetTxPkt *pkt)
 412 {
 413     assert(pkt);
 414
 415     return pkt->packet_type;
 416 }
 417
 418 size_t net_tx_pkt_get_total_len(struct NetTxPkt *pkt)
 419 {
 420     assert(pkt);
 421
 422     return pkt->hdr_len + pkt->payload_len;
 423 }
 424
 425 void net_tx_pkt_dump(struct NetTxPkt *pkt)
 426 {
 427 #ifdef NET_TX_PKT_DEBUG
 428     assert(pkt);
 429
 430     printf("TX PKT: hdr_len: %d, pkt_type: 0x%X, l2hdr_len: %lu, "
 431         "l3hdr_len: %lu, payload_len: %u\n", pkt->hdr_len, pkt->packet_type,
 432         pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len,
 433         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len, pkt->payload_len);
 434 #endif
 435 }
 436
 437 void net_tx_pkt_reset(struct NetTxPkt *pkt)
 438 {
 439     int i;
 440
 441     /* no assert, as reset can be called before tx_pkt_init */
 442     if (!pkt) {
 443         return;
 444     }
 445
 446     memset(&pkt->virt_hdr, 0, sizeof(pkt->virt_hdr));
 447
 448     assert(pkt->vec);
 449
 450     pkt->payload_len = 0;
 451     pkt->payload_frags = 0;
 452
 453     assert(pkt->raw);
 454     for (i = 0; i < pkt->raw_frags; i++) {
 455         assert(pkt->raw[i].iov_base);
 456         pci_dma_unmap(pkt->pci_dev, pkt->raw[i].iov_base, pkt->raw[i].iov_len,
 457                       DMA_DIRECTION_TO_DEVICE, 0);
 458     }
 459     pkt->raw_frags = 0;
 460
 461     pkt->hdr_len = 0;
 462     pkt->l4proto = 0;
 463 }
 464
 465 static void net_tx_pkt_do_sw_csum(struct NetTxPkt *pkt)
 466 {
 467     struct iovec *iov = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
 468     uint32_t csum_cntr;
 469     uint16_t csum = 0;
 470     uint32_t cso;
 471     /* num of iovec without vhdr */
 472     uint32_t iov_len = pkt->payload_frags + NET_TX_PKT_PL_START_FRAG - 1;
 473     uint16_t csl;
 474     size_t csum_offset = pkt->virt_hdr.csum_start + pkt->virt_hdr.csum_offset;
 475     uint16_t l3_proto = eth_get_l3_proto(iov, 1, iov->iov_len);
 476
 477     /* Put zero to checksum field */
 478     iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum);
 479
 480     /* Calculate L4 TCP/UDP checksum */
 481     csl = pkt->payload_len;
 482
 483     csum_cntr = 0;
 484     cso = 0;
 485     /* add pseudo header to csum */
 486     if (l3_proto == ETH_P_IP) {
 487         csum_cntr = eth_calc_ip4_pseudo_hdr_csum(
 488                 pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base,
 489                 csl, &cso);
 490     } else if (l3_proto == ETH_P_IPV6) {
 491         csum_cntr = eth_calc_ip6_pseudo_hdr_csum(
 492                 pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base,
 493                 csl, pkt->l4proto, &cso);
 494     }
 495
 496     /* data checksum */
 497     csum_cntr +=
 498         net_checksum_add_iov(iov, iov_len, pkt->virt_hdr.csum_start, csl, cso);
 499
 500     /* Put the checksum obtained into the packet */
 501     csum = cpu_to_be16(net_checksum_finish_nozero(csum_cntr));
 502     iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum);
 503 }
 504
 505 enum {
 506     NET_TX_PKT_FRAGMENT_L2_HDR_POS = 0,
 507     NET_TX_PKT_FRAGMENT_L3_HDR_POS,
 508     NET_TX_PKT_FRAGMENT_HEADER_NUM
 509 };
 510
 511 #define NET_MAX_FRAG_SG_LIST (64)
 512
 513 static size_t net_tx_pkt_fetch_fragment(struct NetTxPkt *pkt,
 514     int *src_idx, size_t *src_offset, struct iovec *dst, int *dst_idx)
 515 {
 516     size_t fetched = 0;
 517     struct iovec *src = pkt->vec;
 518
 519     *dst_idx = NET_TX_PKT_FRAGMENT_HEADER_NUM;
 520
 521     while (fetched < IP_FRAG_ALIGN_SIZE(pkt->virt_hdr.gso_size)) {
 522
 523         /* no more place in fragment iov */
 524         if (*dst_idx == NET_MAX_FRAG_SG_LIST) {
 525             break;
 526         }
 527
 528         /* no more data in iovec */
 529         if (*src_idx == (pkt->payload_frags + NET_TX_PKT_PL_START_FRAG)) {
 530             break;
 531         }
 532
 533
 534         dst[*dst_idx].iov_base = src[*src_idx].iov_base + *src_offset;
 535         dst[*dst_idx].iov_len = MIN(src[*src_idx].iov_len - *src_offset,
 536             IP_FRAG_ALIGN_SIZE(pkt->virt_hdr.gso_size) - fetched);
 537
 538         *src_offset += dst[*dst_idx].iov_len;
 539         fetched += dst[*dst_idx].iov_len;
 540
 541         if (*src_offset == src[*src_idx].iov_len) {
 542             *src_offset = 0;
 543             (*src_idx)++;
 544         }
 545
 546         (*dst_idx)++;
 547     }
 548
 549     return fetched;
 550 }
 551
 552 static inline void net_tx_pkt_sendv(struct NetTxPkt *pkt,
 553     NetClientState *nc, const struct iovec *iov, int iov_cnt)
 554 {
 555     if (pkt->is_loopback) {
 556         nc->info->receive_iov(nc, iov, iov_cnt);
 557     } else {
 558         qemu_sendv_packet(nc, iov, iov_cnt);
 559     }
 560 }
 561
 562 static bool net_tx_pkt_do_sw_fragmentation(struct NetTxPkt *pkt,
 563     NetClientState *nc)
 564 {
 565     struct iovec fragment[NET_MAX_FRAG_SG_LIST];
 566     size_t fragment_len = 0;
 567     bool more_frags = false;
 568
 569     /* some pointers for shorter code */
 570     void *l2_iov_base, *l3_iov_base;
 571     size_t l2_iov_len, l3_iov_len;
 572     int src_idx =  NET_TX_PKT_PL_START_FRAG, dst_idx;
 573     size_t src_offset = 0;
 574     size_t fragment_offset = 0;
 575
 576     l2_iov_base = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base;
 577     l2_iov_len = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len;
 578     l3_iov_base = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
 579     l3_iov_len = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len;
 580
 581     /* Copy headers */
 582     fragment[NET_TX_PKT_FRAGMENT_L2_HDR_POS].iov_base = l2_iov_base;
 583     fragment[NET_TX_PKT_FRAGMENT_L2_HDR_POS].iov_len = l2_iov_len;
 584     fragment[NET_TX_PKT_FRAGMENT_L3_HDR_POS].iov_base = l3_iov_base;
 585     fragment[NET_TX_PKT_FRAGMENT_L3_HDR_POS].iov_len = l3_iov_len;
 586
 587
 588     /* Put as much data as possible and send */
 589     do {
 590         fragment_len = net_tx_pkt_fetch_fragment(pkt, &src_idx, &src_offset,
 591             fragment, &dst_idx);
 592
 593         more_frags = (fragment_offset + fragment_len < pkt->payload_len);
 594
 595         eth_setup_ip4_fragmentation(l2_iov_base, l2_iov_len, l3_iov_base,
 596             l3_iov_len, fragment_len, fragment_offset, more_frags);
 597
 598         eth_fix_ip4_checksum(l3_iov_base, l3_iov_len);
 599
 600         net_tx_pkt_sendv(pkt, nc, fragment, dst_idx);
 601
 602         fragment_offset += fragment_len;
 603
 604     } while (fragment_len && more_frags);
 605
 606     return true;
 607 }
 608
 609 bool net_tx_pkt_send(struct NetTxPkt *pkt, NetClientState *nc)
 610 {
 611     assert(pkt);
 612
 613     if (!pkt->has_virt_hdr &&
 614         pkt->virt_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 615         net_tx_pkt_do_sw_csum(pkt);
 616     }
 617
 618     /*
 619      * Since underlying infrastructure does not support IP datagrams longer
 620      * than 64K we should drop such packets and don't even try to send
 621      */
 622     if (VIRTIO_NET_HDR_GSO_NONE != pkt->virt_hdr.gso_type) {
 623         if (pkt->payload_len >
 624             ETH_MAX_IP_DGRAM_LEN -
 625             pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len) {
 626             return false;
 627         }
 628     }
 629
 630     if (pkt->has_virt_hdr ||
 631         pkt->virt_hdr.gso_type == VIRTIO_NET_HDR_GSO_NONE) {
 632         net_tx_pkt_fix_ip6_payload_len(pkt);
 633         net_tx_pkt_sendv(pkt, nc, pkt->vec,
 634             pkt->payload_frags + NET_TX_PKT_PL_START_FRAG);
 635         return true;
 636     }
 637
 638     return net_tx_pkt_do_sw_fragmentation(pkt, nc);
 639 }
 640
 641 bool net_tx_pkt_send_loopback(struct NetTxPkt *pkt, NetClientState *nc)
 642 {
 643     bool res;
 644
 645     pkt->is_loopback = true;
 646     res = net_tx_pkt_send(pkt, nc);
 647     pkt->is_loopback = false;
 648
 649     return res;
 650 }
 651
 652 void net_tx_pkt_fix_ip6_payload_len(struct NetTxPkt *pkt)
 653 {
 654     struct iovec *l2 = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
 655     if (eth_get_l3_proto(l2, 1, l2->iov_len) == ETH_P_IPV6) {
 656         struct ip6_header *ip6 = (struct ip6_header *) pkt->l3_hdr;
 657         /*
 658          * TODO: if qemu would support >64K packets - add jumbo option check
 659          * something like that:
 660          * 'if (ip6->ip6_plen == 0 && !has_jumbo_option(ip6)) {'
 661          */
 662         if (ip6->ip6_plen == 0) {
 663             if (pkt->payload_len <= ETH_MAX_IP_DGRAM_LEN) {
 664                 ip6->ip6_plen = htons(pkt->payload_len);
 665             }
 666             /*
 667              * TODO: if qemu would support >64K packets
 668              * add jumbo option for packets greater then 65,535 bytes
 669              */
 670         }
 671     }
 672 }