trafgen_l3.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Subject to the GPL, version 2.
   4  */
   5
   6 #include <net/if_arp.h>
   7
   8 #include "die.h"
   9 #include "dev.h"
  10 #include "csum.h"
  11 #include "built_in.h"
  12 #include "trafgen_l2.h"
  13 #include "trafgen_l3.h"
  14 #include "trafgen_proto.h"
  15 #include "trafgen_conf.h"
  16
  17 static struct proto_field ipv4_fields[] = {
  18         { .id = IP4_VER,       .len = 1, .offset = 0, .shift = 4, .mask = 0xf0 },
  19         { .id = IP4_IHL,       .len = 1, .offset = 0, .shift = 0, .mask = 0x0f },
  20         { .id = IP4_DSCP,      .len = 1, .offset = 1, .shift = 2, .mask = 0xfc },
  21         { .id = IP4_ECN,       .len = 1, .offset = 1, .shift = 0, .mask = 0x03 },
  22         { .id = IP4_TOS,       .len = 1, .offset = 1 },
  23         { .id = IP4_LEN,       .len = 2, .offset = 2 },
  24         { .id = IP4_ID,        .len = 2, .offset = 4 },
  25         { .id = IP4_FLAGS,     .len = 2, .offset = 6, .shift = 13, .mask = 0xe000 },
  26         { .id = IP4_MF,        .len = 2, .offset = 6, .shift = 13, .mask = 0x2000 },
  27         { .id = IP4_DF,        .len = 2, .offset = 6, .shift = 14, .mask = 0x4000 },
  28         { .id = IP4_FRAG_OFFS, .len = 2, .offset = 6, .shift = 0,  .mask = 0x1fff },
  29         { .id = IP4_TTL,       .len = 1, .offset = 8 },
  30         { .id = IP4_PROTO,     .len = 1, .offset = 9 },
  31         { .id = IP4_CSUM,      .len = 2, .offset = 10 },
  32         { .id = IP4_SADDR,     .len = 4, .offset = 12 },
  33         { .id = IP4_DADDR,     .len = 4, .offset = 16 },
  34 };
  35
  36 static void ipv4_header_init(struct proto_hdr *hdr)
  37 {
  38         const char *dev = proto_dev_get();
  39
  40         /* In case of tun interface we do not need to create Ethernet header */
  41         if (dev && device_mtu(dev) && device_type(dev) != ARPHRD_NONE)
  42                 proto_lower_default_add(hdr, PROTO_ETH);
  43
  44         proto_header_fields_add(hdr, ipv4_fields, array_size(ipv4_fields));
  45
  46         proto_hdr_field_set_default_u8(hdr, IP4_VER, 4);
  47         proto_hdr_field_set_default_u8(hdr, IP4_IHL, 5);
  48         proto_hdr_field_set_default_dev_ipv4(hdr, IP4_SADDR);
  49 }
  50
  51 static void ipv4_field_changed(struct proto_field *field)
  52 {
  53         field->hdr->is_csum_valid = false;
  54
  55         if (field->id == IP4_SADDR || field->id == IP4_DADDR) {
  56                 struct proto_hdr *upper = proto_upper_header(field->hdr);
  57
  58                 if (upper && (upper->ops->id == PROTO_UDP || upper->ops->id == PROTO_TCP))
  59                         upper->is_csum_valid = false;
  60         }
  61 }
  62
  63 static void ipv4_csum_update(struct proto_hdr *hdr)
  64 {
  65         struct packet *pkt;
  66         uint16_t csum;
  67
  68         if (hdr->is_csum_valid)
  69                 return;
  70         if (proto_hdr_field_is_set(hdr, IP4_CSUM))
  71                 return;
  72
  73         pkt = packet_get(hdr->pkt_id);
  74
  75         proto_hdr_field_set_default_u16(hdr, IP4_CSUM, 0);
  76         csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], hdr->len));
  77         proto_hdr_field_set_default_u16(hdr, IP4_CSUM, bswap_16(csum));
  78
  79         hdr->is_csum_valid = true;
  80 }
  81
  82 static void ipv4_packet_finish(struct proto_hdr *hdr)
  83 {
  84         struct packet *pkt = current_packet();
  85         uint16_t total_len;
  86
  87         total_len = pkt->len - hdr->pkt_offset;
  88         proto_hdr_field_set_default_be16(hdr, IP4_LEN, total_len);
  89
  90         ipv4_csum_update(hdr);
  91 }
  92
  93 static void ipv4_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  94 {
  95         uint8_t ip_proto;
  96
  97         switch (pid) {
  98         case PROTO_IP4:
  99                 ip_proto = IPPROTO_IPIP;
 100                 break;
 101         case PROTO_IP6:
 102                 ip_proto = IPPROTO_IPV6;
 103                 break;
 104         case PROTO_ICMP4:
 105                 ip_proto = IPPROTO_ICMP;
 106                 break;
 107         case PROTO_UDP:
 108                 ip_proto = IPPROTO_UDP;
 109                 break;
 110         case PROTO_TCP:
 111                 ip_proto = IPPROTO_TCP;
 112                 break;
 113         default:
 114                 bug();
 115         }
 116
 117         proto_hdr_field_set_default_u8(hdr, IP4_PROTO, ip_proto);
 118 }
 119
 120 static const struct proto_ops ipv4_proto_ops = {
 121         .id             = PROTO_IP4,
 122         .layer          = PROTO_L3,
 123         .header_init    = ipv4_header_init,
 124         .packet_update  = ipv4_csum_update,
 125         .field_changed  = ipv4_field_changed,
 126         .packet_finish  = ipv4_packet_finish,
 127         .set_next_proto = ipv4_set_next_proto,
 128 };
 129
 130 static struct proto_field ipv6_fields[] = {
 131         { .id = IP6_VER,       .len = 4,  .offset = 0, .shift = 28, .mask = 0xf0000000 },
 132         { .id = IP6_CLASS,     .len = 4,  .offset = 0, .shift = 20, .mask = 0x0ff00000 },
 133         { .id = IP6_FLOW_LBL,  .len = 4,  .offset = 0, .shift = 0,  .mask = 0x000fffff },
 134         { .id = IP6_LEN,       .len = 2,  .offset = 4 },
 135         { .id = IP6_NEXT_HDR,  .len = 1,  .offset = 6 },
 136         { .id = IP6_HOP_LIMIT, .len = 1,  .offset = 7 },
 137         { .id = IP6_SADDR,     .len = 16, .offset = 8 },
 138         { .id = IP6_DADDR,     .len = 16, .offset = 24 },
 139 };
 140
 141 static void ipv6_header_init(struct proto_hdr *hdr)
 142 {
 143         const char *dev = proto_dev_get();
 144
 145         /* In case of tun interface we do not need to create Ethernet header */
 146         if (dev && device_mtu(dev) && device_type(dev) != ARPHRD_NONE)
 147                 proto_lower_default_add(hdr, PROTO_ETH);
 148
 149         proto_header_fields_add(hdr, ipv6_fields, array_size(ipv6_fields));
 150
 151         proto_hdr_field_set_default_be32(hdr, IP6_VER, 6);
 152         proto_hdr_field_set_default_dev_ipv6(hdr, IP6_SADDR);
 153 }
 154
 155 static void ipv6_field_changed(struct proto_field *field)
 156 {
 157         if (field->id == IP6_SADDR || field->id == IP6_DADDR) {
 158                 struct proto_hdr *upper = proto_upper_header(field->hdr);
 159
 160                 if (upper && (upper->ops->id == PROTO_UDP || upper->ops->id == PROTO_TCP))
 161                         upper->is_csum_valid = false;
 162         }
 163 }
 164
 165 #define IPV6_HDR_LEN 40
 166
 167 static void ipv6_packet_finish(struct proto_hdr *hdr)
 168 {
 169         struct packet *pkt = current_packet();
 170         uint16_t total_len = pkt->len - hdr->pkt_offset - IPV6_HDR_LEN;
 171
 172         proto_hdr_field_set_default_be16(hdr, IP6_LEN, total_len);
 173 }
 174
 175 static void ipv6_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
 176 {
 177         uint8_t ip_proto;
 178
 179         switch (pid) {
 180         case PROTO_ICMP6:
 181                 ip_proto = IPPROTO_ICMPV6;
 182                 break;
 183         case PROTO_UDP:
 184                 ip_proto = IPPROTO_UDP;
 185                 break;
 186         case PROTO_TCP:
 187                 ip_proto = IPPROTO_TCP;
 188                 break;
 189         default:
 190                 bug();
 191         }
 192
 193         proto_hdr_field_set_default_u8(hdr, IP6_NEXT_HDR, ip_proto);
 194 }
 195
 196 static const struct proto_ops ipv6_proto_ops = {
 197         .id             = PROTO_IP6,
 198         .layer          = PROTO_L3,
 199         .header_init    = ipv6_header_init,
 200         .field_changed  = ipv6_field_changed,
 201         .packet_finish  = ipv6_packet_finish,
 202         .set_next_proto = ipv6_set_next_proto,
 203 };
 204
 205 void protos_l3_init(void)
 206 {
 207         proto_ops_register(&ipv4_proto_ops);
 208         proto_ops_register(&ipv6_proto_ops);
 209 }