net_tx_pkt.c - qemu - FORK: QEMU emulator

net_tx_pkt.c (18890B)
      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     if (pkt->max_raw_frags > 0) {
    454         assert(pkt->raw);
    455         for (i = 0; i < pkt->raw_frags; i++) {
    456             assert(pkt->raw[i].iov_base);
    457             pci_dma_unmap(pkt->pci_dev, pkt->raw[i].iov_base,
    458                           pkt->raw[i].iov_len, DMA_DIRECTION_TO_DEVICE, 0);
    459         }
    460     }
    461     pkt->raw_frags = 0;
    462 
    463     pkt->hdr_len = 0;
    464     pkt->l4proto = 0;
    465 }
    466 
    467 static void net_tx_pkt_do_sw_csum(struct NetTxPkt *pkt)
    468 {
    469     struct iovec *iov = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
    470     uint32_t csum_cntr;
    471     uint16_t csum = 0;
    472     uint32_t cso;
    473     /* num of iovec without vhdr */
    474     uint32_t iov_len = pkt->payload_frags + NET_TX_PKT_PL_START_FRAG - 1;
    475     uint16_t csl;
    476     size_t csum_offset = pkt->virt_hdr.csum_start + pkt->virt_hdr.csum_offset;
    477     uint16_t l3_proto = eth_get_l3_proto(iov, 1, iov->iov_len);
    478 
    479     /* Put zero to checksum field */
    480     iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum);
    481 
    482     /* Calculate L4 TCP/UDP checksum */
    483     csl = pkt->payload_len;
    484 
    485     csum_cntr = 0;
    486     cso = 0;
    487     /* add pseudo header to csum */
    488     if (l3_proto == ETH_P_IP) {
    489         csum_cntr = eth_calc_ip4_pseudo_hdr_csum(
    490                 pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base,
    491                 csl, &cso);
    492     } else if (l3_proto == ETH_P_IPV6) {
    493         csum_cntr = eth_calc_ip6_pseudo_hdr_csum(
    494                 pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base,
    495                 csl, pkt->l4proto, &cso);
    496     }
    497 
    498     /* data checksum */
    499     csum_cntr +=
    500         net_checksum_add_iov(iov, iov_len, pkt->virt_hdr.csum_start, csl, cso);
    501 
    502     /* Put the checksum obtained into the packet */
    503     csum = cpu_to_be16(net_checksum_finish_nozero(csum_cntr));
    504     iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum);
    505 }
    506 
    507 enum {
    508     NET_TX_PKT_FRAGMENT_L2_HDR_POS = 0,
    509     NET_TX_PKT_FRAGMENT_L3_HDR_POS,
    510     NET_TX_PKT_FRAGMENT_HEADER_NUM
    511 };
    512 
    513 #define NET_MAX_FRAG_SG_LIST (64)
    514 
    515 static size_t net_tx_pkt_fetch_fragment(struct NetTxPkt *pkt,
    516     int *src_idx, size_t *src_offset, struct iovec *dst, int *dst_idx)
    517 {
    518     size_t fetched = 0;
    519     struct iovec *src = pkt->vec;
    520 
    521     *dst_idx = NET_TX_PKT_FRAGMENT_HEADER_NUM;
    522 
    523     while (fetched < IP_FRAG_ALIGN_SIZE(pkt->virt_hdr.gso_size)) {
    524 
    525         /* no more place in fragment iov */
    526         if (*dst_idx == NET_MAX_FRAG_SG_LIST) {
    527             break;
    528         }
    529 
    530         /* no more data in iovec */
    531         if (*src_idx == (pkt->payload_frags + NET_TX_PKT_PL_START_FRAG)) {
    532             break;
    533         }
    534 
    535 
    536         dst[*dst_idx].iov_base = src[*src_idx].iov_base + *src_offset;
    537         dst[*dst_idx].iov_len = MIN(src[*src_idx].iov_len - *src_offset,
    538             IP_FRAG_ALIGN_SIZE(pkt->virt_hdr.gso_size) - fetched);
    539 
    540         *src_offset += dst[*dst_idx].iov_len;
    541         fetched += dst[*dst_idx].iov_len;
    542 
    543         if (*src_offset == src[*src_idx].iov_len) {
    544             *src_offset = 0;
    545             (*src_idx)++;
    546         }
    547 
    548         (*dst_idx)++;
    549     }
    550 
    551     return fetched;
    552 }
    553 
    554 static inline void net_tx_pkt_sendv(struct NetTxPkt *pkt,
    555     NetClientState *nc, const struct iovec *iov, int iov_cnt)
    556 {
    557     if (pkt->is_loopback) {
    558         qemu_receive_packet_iov(nc, iov, iov_cnt);
    559     } else {
    560         qemu_sendv_packet(nc, iov, iov_cnt);
    561     }
    562 }
    563 
    564 static bool net_tx_pkt_do_sw_fragmentation(struct NetTxPkt *pkt,
    565     NetClientState *nc)
    566 {
    567     struct iovec fragment[NET_MAX_FRAG_SG_LIST];
    568     size_t fragment_len = 0;
    569     bool more_frags = false;
    570 
    571     /* some pointers for shorter code */
    572     void *l2_iov_base, *l3_iov_base;
    573     size_t l2_iov_len, l3_iov_len;
    574     int src_idx =  NET_TX_PKT_PL_START_FRAG, dst_idx;
    575     size_t src_offset = 0;
    576     size_t fragment_offset = 0;
    577 
    578     l2_iov_base = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base;
    579     l2_iov_len = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len;
    580     l3_iov_base = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
    581     l3_iov_len = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len;
    582 
    583     /* Copy headers */
    584     fragment[NET_TX_PKT_FRAGMENT_L2_HDR_POS].iov_base = l2_iov_base;
    585     fragment[NET_TX_PKT_FRAGMENT_L2_HDR_POS].iov_len = l2_iov_len;
    586     fragment[NET_TX_PKT_FRAGMENT_L3_HDR_POS].iov_base = l3_iov_base;
    587     fragment[NET_TX_PKT_FRAGMENT_L3_HDR_POS].iov_len = l3_iov_len;
    588 
    589 
    590     /* Put as much data as possible and send */
    591     do {
    592         fragment_len = net_tx_pkt_fetch_fragment(pkt, &src_idx, &src_offset,
    593             fragment, &dst_idx);
    594 
    595         more_frags = (fragment_offset + fragment_len < pkt->payload_len);
    596 
    597         eth_setup_ip4_fragmentation(l2_iov_base, l2_iov_len, l3_iov_base,
    598             l3_iov_len, fragment_len, fragment_offset, more_frags);
    599 
    600         eth_fix_ip4_checksum(l3_iov_base, l3_iov_len);
    601 
    602         net_tx_pkt_sendv(pkt, nc, fragment, dst_idx);
    603 
    604         fragment_offset += fragment_len;
    605 
    606     } while (fragment_len && more_frags);
    607 
    608     return true;
    609 }
    610 
    611 bool net_tx_pkt_send(struct NetTxPkt *pkt, NetClientState *nc)
    612 {
    613     assert(pkt);
    614 
    615     if (!pkt->has_virt_hdr &&
    616         pkt->virt_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
    617         net_tx_pkt_do_sw_csum(pkt);
    618     }
    619 
    620     /*
    621      * Since underlying infrastructure does not support IP datagrams longer
    622      * than 64K we should drop such packets and don't even try to send
    623      */
    624     if (VIRTIO_NET_HDR_GSO_NONE != pkt->virt_hdr.gso_type) {
    625         if (pkt->payload_len >
    626             ETH_MAX_IP_DGRAM_LEN -
    627             pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len) {
    628             return false;
    629         }
    630     }
    631 
    632     if (pkt->has_virt_hdr ||
    633         pkt->virt_hdr.gso_type == VIRTIO_NET_HDR_GSO_NONE) {
    634         net_tx_pkt_fix_ip6_payload_len(pkt);
    635         net_tx_pkt_sendv(pkt, nc, pkt->vec,
    636             pkt->payload_frags + NET_TX_PKT_PL_START_FRAG);
    637         return true;
    638     }
    639 
    640     return net_tx_pkt_do_sw_fragmentation(pkt, nc);
    641 }
    642 
    643 bool net_tx_pkt_send_loopback(struct NetTxPkt *pkt, NetClientState *nc)
    644 {
    645     bool res;
    646 
    647     pkt->is_loopback = true;
    648     res = net_tx_pkt_send(pkt, nc);
    649     pkt->is_loopback = false;
    650 
    651     return res;
    652 }
    653 
    654 void net_tx_pkt_fix_ip6_payload_len(struct NetTxPkt *pkt)
    655 {
    656     struct iovec *l2 = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
    657     if (eth_get_l3_proto(l2, 1, l2->iov_len) == ETH_P_IPV6) {
    658         struct ip6_header *ip6 = (struct ip6_header *) pkt->l3_hdr;
    659         /*
    660          * TODO: if qemu would support >64K packets - add jumbo option check
    661          * something like that:
    662          * 'if (ip6->ip6_plen == 0 && !has_jumbo_option(ip6)) {'
    663          */
    664         if (ip6->ip6_plen == 0) {
    665             if (pkt->payload_len <= ETH_MAX_IP_DGRAM_LEN) {
    666                 ip6->ip6_plen = htons(pkt->payload_len);
    667             }
    668             /*
    669              * TODO: if qemu would support >64K packets
    670              * add jumbo option for packets greater then 65,535 bytes
    671              */
    672         }
    673     }
    674 }
	qemu FORK: QEMU emulator
	git clone https://git.neptards.moe/neptards/qemu.git
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