net/eth.c

   1 /*
   2  * QEMU network structures definitions and helper functions
   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 "net/eth.h"
  19 #include "net/checksum.h"
  20 #include "qemu-common.h"
  21 #include "net/tap.h"
  22
  23 void eth_setup_vlan_headers(struct eth_header *ehdr, uint16_t vlan_tag,
  24     bool *is_new)
  25 {
  26     struct vlan_header *vhdr = PKT_GET_VLAN_HDR(ehdr);
  27
  28     switch (be16_to_cpu(ehdr->h_proto)) {
  29     case ETH_P_VLAN:
  30     case ETH_P_DVLAN:
  31         /* vlan hdr exists */
  32         *is_new = false;
  33         break;
  34
  35     default:
  36         /* No VLAN header, put a new one */
  37         vhdr->h_proto = ehdr->h_proto;
  38         ehdr->h_proto = cpu_to_be16(ETH_P_VLAN);
  39         *is_new = true;
  40         break;
  41     }
  42     vhdr->h_tci = cpu_to_be16(vlan_tag);
  43 }
  44
  45 uint8_t
  46 eth_get_gso_type(uint16_t l3_proto, uint8_t *l3_hdr, uint8_t l4proto)
  47 {
  48     uint8_t ecn_state = 0;
  49
  50     if (l3_proto == ETH_P_IP) {
  51         struct ip_header *iphdr = (struct ip_header *) l3_hdr;
  52
  53         if (IP_HEADER_VERSION(iphdr) == IP_HEADER_VERSION_4) {
  54             if (IPTOS_ECN(iphdr->ip_tos) == IPTOS_ECN_CE) {
  55                 ecn_state = VIRTIO_NET_HDR_GSO_ECN;
  56             }
  57             if (l4proto == IP_PROTO_TCP) {
  58                 return VIRTIO_NET_HDR_GSO_TCPV4 | ecn_state;
  59             } else if (l4proto == IP_PROTO_UDP) {
  60                 return VIRTIO_NET_HDR_GSO_UDP | ecn_state;
  61             }
  62         }
  63     } else if (l3_proto == ETH_P_IPV6) {
  64         struct ip6_header *ip6hdr = (struct ip6_header *) l3_hdr;
  65
  66         if (IP6_ECN(ip6hdr->ip6_ecn_acc) == IP6_ECN_CE) {
  67             ecn_state = VIRTIO_NET_HDR_GSO_ECN;
  68         }
  69
  70         if (l4proto == IP_PROTO_TCP) {
  71             return VIRTIO_NET_HDR_GSO_TCPV6 | ecn_state;
  72         }
  73     }
  74
  75     /* Unsupported offload */
  76     g_assert_not_reached();
  77
  78     return VIRTIO_NET_HDR_GSO_NONE | ecn_state;
  79 }
  80
  81 void eth_get_protocols(const uint8_t *headers,
  82                        uint32_t hdr_length,
  83                        bool *isip4, bool *isip6,
  84                        bool *isudp, bool *istcp)
  85 {
  86     int proto;
  87     size_t l2hdr_len = eth_get_l2_hdr_length(headers);
  88     assert(hdr_length >= eth_get_l2_hdr_length(headers));
  89     *isip4 = *isip6 = *isudp = *istcp = false;
  90
  91     proto = eth_get_l3_proto(headers, l2hdr_len);
  92     if (proto == ETH_P_IP) {
  93         *isip4 = true;
  94
  95         struct ip_header *iphdr;
  96
  97         assert(hdr_length >=
  98             eth_get_l2_hdr_length(headers) + sizeof(struct ip_header));
  99
 100         iphdr = PKT_GET_IP_HDR(headers);
 101
 102         if (IP_HEADER_VERSION(iphdr) == IP_HEADER_VERSION_4) {
 103             if (iphdr->ip_p == IP_PROTO_TCP) {
 104                 *istcp = true;
 105             } else if (iphdr->ip_p == IP_PROTO_UDP) {
 106                 *isudp = true;
 107             }
 108         }
 109     } else if (proto == ETH_P_IPV6) {
 110         uint8_t l4proto;
 111         size_t full_ip6hdr_len;
 112
 113         struct iovec hdr_vec;
 114         hdr_vec.iov_base = (void *) headers;
 115         hdr_vec.iov_len = hdr_length;
 116
 117         *isip6 = true;
 118         if (eth_parse_ipv6_hdr(&hdr_vec, 1, l2hdr_len,
 119                               &l4proto, &full_ip6hdr_len)) {
 120             if (l4proto == IP_PROTO_TCP) {
 121                 *istcp = true;
 122             } else if (l4proto == IP_PROTO_UDP) {
 123                 *isudp = true;
 124             }
 125         }
 126     }
 127 }
 128
 129 void
 130 eth_setup_ip4_fragmentation(const void *l2hdr, size_t l2hdr_len,
 131                             void *l3hdr, size_t l3hdr_len,
 132                             size_t l3payload_len,
 133                             size_t frag_offset, bool more_frags)
 134 {
 135     if (eth_get_l3_proto(l2hdr, l2hdr_len) == ETH_P_IP) {
 136         uint16_t orig_flags;
 137         struct ip_header *iphdr = (struct ip_header *) l3hdr;
 138         uint16_t frag_off_units = frag_offset / IP_FRAG_UNIT_SIZE;
 139         uint16_t new_ip_off;
 140
 141         assert(frag_offset % IP_FRAG_UNIT_SIZE == 0);
 142         assert((frag_off_units & ~IP_OFFMASK) == 0);
 143
 144         orig_flags = be16_to_cpu(iphdr->ip_off) & ~(IP_OFFMASK|IP_MF);
 145         new_ip_off = frag_off_units | orig_flags  | (more_frags ? IP_MF : 0);
 146         iphdr->ip_off = cpu_to_be16(new_ip_off);
 147         iphdr->ip_len = cpu_to_be16(l3payload_len + l3hdr_len);
 148     }
 149 }
 150
 151 void
 152 eth_fix_ip4_checksum(void *l3hdr, size_t l3hdr_len)
 153 {
 154     struct ip_header *iphdr = (struct ip_header *) l3hdr;
 155     iphdr->ip_sum = 0;
 156     iphdr->ip_sum = cpu_to_be16(net_raw_checksum(l3hdr, l3hdr_len));
 157 }
 158
 159 uint32_t
 160 eth_calc_pseudo_hdr_csum(struct ip_header *iphdr, uint16_t csl)
 161 {
 162     struct ip_pseudo_header ipph;
 163     ipph.ip_src = iphdr->ip_src;
 164     ipph.ip_dst = iphdr->ip_dst;
 165     ipph.ip_payload = cpu_to_be16(csl);
 166     ipph.ip_proto = iphdr->ip_p;
 167     ipph.zeros = 0;
 168     return net_checksum_add(sizeof(ipph), (uint8_t *) &ipph);
 169 }
 170
 171 static bool
 172 eth_is_ip6_extension_header_type(uint8_t hdr_type)
 173 {
 174     switch (hdr_type) {
 175     case IP6_HOP_BY_HOP:
 176     case IP6_ROUTING:
 177     case IP6_FRAGMENT:
 178     case IP6_ESP:
 179     case IP6_AUTHENTICATION:
 180     case IP6_DESTINATON:
 181     case IP6_MOBILITY:
 182         return true;
 183     default:
 184         return false;
 185     }
 186 }
 187
 188 bool eth_parse_ipv6_hdr(struct iovec *pkt, int pkt_frags,
 189                         size_t ip6hdr_off, uint8_t *l4proto,
 190                         size_t *full_hdr_len)
 191 {
 192     struct ip6_header ip6_hdr;
 193     struct ip6_ext_hdr ext_hdr;
 194     size_t bytes_read;
 195
 196     bytes_read = iov_to_buf(pkt, pkt_frags, ip6hdr_off,
 197                             &ip6_hdr, sizeof(ip6_hdr));
 198     if (bytes_read < sizeof(ip6_hdr)) {
 199         return false;
 200     }
 201
 202     *full_hdr_len = sizeof(struct ip6_header);
 203
 204     if (!eth_is_ip6_extension_header_type(ip6_hdr.ip6_nxt)) {
 205         *l4proto = ip6_hdr.ip6_nxt;
 206         return true;
 207     }
 208
 209     do {
 210         bytes_read = iov_to_buf(pkt, pkt_frags, ip6hdr_off + *full_hdr_len,
 211                                 &ext_hdr, sizeof(ext_hdr));
 212         *full_hdr_len += (ext_hdr.ip6r_len + 1) * IP6_EXT_GRANULARITY;
 213     } while (eth_is_ip6_extension_header_type(ext_hdr.ip6r_nxt));
 214
 215     *l4proto = ext_hdr.ip6r_nxt;
 216     return true;
 217 }