trafgen_l3.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Subject to the GPL, version 2.
   4  */
   5
   6 #include <linux/if_ether.h>
   7
   8 #include "die.h"
   9 #include "csum.h"
  10 #include "built_in.h"
  11 #include "trafgen_l2.h"
  12 #include "trafgen_l3.h"
  13 #include "trafgen_proto.h"
  14 #include "trafgen_conf.h"
  15
  16 static struct proto_field ipv4_fields[] = {
  17         { .id = IP4_VER,       .len = 1, .offset = 0, .shift = 4, .mask = 0xf0 },
  18         { .id = IP4_IHL,       .len = 1, .offset = 0, .shift = 0, .mask = 0x0f },
  19         { .id = IP4_DSCP,      .len = 1, .offset = 1, .shift = 2, .mask = 0xfc },
  20         { .id = IP4_ECN,       .len = 1, .offset = 1, .shift = 0, .mask = 0x03 },
  21         { .id = IP4_TOS,       .len = 1, .offset = 1 },
  22         { .id = IP4_LEN,       .len = 2, .offset = 2 },
  23         { .id = IP4_ID,        .len = 2, .offset = 4 },
  24         { .id = IP4_FLAGS,     .len = 2, .offset = 6, .shift = 13, .mask = 0xe000 },
  25         { .id = IP4_MF,        .len = 2, .offset = 6, .shift = 13, .mask = 0x2000 },
  26         { .id = IP4_DF,        .len = 2, .offset = 6, .shift = 14, .mask = 0x4000 },
  27         { .id = IP4_FRAG_OFFS, .len = 2, .offset = 6, .shift = 0,  .mask = 0x1fff },
  28         { .id = IP4_TTL,       .len = 1, .offset = 8 },
  29         { .id = IP4_PROTO,     .len = 1, .offset = 9 },
  30         { .id = IP4_CSUM,      .len = 2, .offset = 10 },
  31         { .id = IP4_SADDR,     .len = 4, .offset = 12 },
  32         { .id = IP4_DADDR,     .len = 4, .offset = 16 },
  33 };
  34
  35 static void ipv4_header_init(struct proto_hdr *hdr)
  36 {
  37         proto_lower_default_add(hdr, PROTO_ETH);
  38
  39         proto_header_fields_add(hdr, ipv4_fields, array_size(ipv4_fields));
  40
  41         proto_field_set_default_u8(hdr, IP4_VER, 4);
  42         proto_field_set_default_u8(hdr, IP4_IHL, 5);
  43 }
  44
  45 static void ipv4_field_changed(struct proto_field *field)
  46 {
  47         field->hdr->is_csum_valid = false;
  48
  49         if (field->id == IP4_SADDR || field->id == IP4_DADDR) {
  50                 struct proto_hdr *upper = proto_upper_header(field->hdr);
  51
  52                 if (upper && (upper->ops->id == PROTO_UDP || upper->ops->id == PROTO_TCP))
  53                         upper->is_csum_valid = false;
  54         }
  55 }
  56
  57 static void ipv4_csum_update(struct proto_hdr *hdr)
  58 {
  59         struct packet *pkt;
  60         uint16_t csum;
  61
  62         if (hdr->is_csum_valid)
  63                 return;
  64         if (proto_field_is_set(hdr, IP4_CSUM))
  65                 return;
  66
  67         pkt = packet_get(hdr->pkt_id);
  68
  69         proto_field_set_default_u16(hdr, IP4_CSUM, 0);
  70         csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], hdr->len));
  71         proto_field_set_default_u16(hdr, IP4_CSUM, bswap_16(csum));
  72
  73         hdr->is_csum_valid = true;
  74 }
  75
  76 static void ipv4_packet_finish(struct proto_hdr *hdr)
  77 {
  78         struct packet *pkt = current_packet();
  79         uint16_t total_len;
  80
  81         total_len = pkt->len - hdr->pkt_offset;
  82         proto_field_set_default_be16(hdr, IP4_LEN, total_len);
  83         proto_field_set_default_dev_ipv4(hdr, IP4_SADDR);
  84
  85         ipv4_csum_update(hdr);
  86 }
  87
  88 static void ipv4_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  89 {
  90         uint8_t ip_proto;
  91
  92         switch (pid) {
  93         case PROTO_IP4:
  94                 ip_proto = IPPROTO_IPIP;
  95                 break;
  96         case PROTO_IP6:
  97                 ip_proto = IPPROTO_IPV6;
  98                 break;
  99         case PROTO_ICMP4:
 100                 ip_proto = IPPROTO_ICMP;
 101                 break;
 102         case PROTO_UDP:
 103                 ip_proto = IPPROTO_UDP;
 104                 break;
 105         case PROTO_TCP:
 106                 ip_proto = IPPROTO_TCP;
 107                 break;
 108         default:
 109                 bug();
 110         }
 111
 112         proto_field_set_default_u8(hdr, IP4_PROTO, ip_proto);
 113 }
 114
 115 static const struct proto_ops ipv4_proto_ops = {
 116         .id             = PROTO_IP4,
 117         .layer          = PROTO_L3,
 118         .header_init    = ipv4_header_init,
 119         .packet_update  = ipv4_csum_update,
 120         .field_changed  = ipv4_field_changed,
 121         .packet_finish  = ipv4_packet_finish,
 122         .set_next_proto = ipv4_set_next_proto,
 123 };
 124
 125 static struct proto_field ipv6_fields[] = {
 126         { .id = IP6_VER,       .len = 4,  .offset = 0, .shift = 28, .mask = 0xf0000000 },
 127         { .id = IP6_CLASS,     .len = 4,  .offset = 0, .shift = 20, .mask = 0x0ff00000 },
 128         { .id = IP6_FLOW_LBL,  .len = 4,  .offset = 0, .shift = 0,  .mask = 0x000fffff },
 129         { .id = IP6_LEN,       .len = 2,  .offset = 4 },
 130         { .id = IP6_NEXT_HDR,  .len = 1,  .offset = 6 },
 131         { .id = IP6_HOP_LIMIT, .len = 1,  .offset = 7 },
 132         { .id = IP6_SADDR,     .len = 16, .offset = 8 },
 133         { .id = IP6_DADDR,     .len = 16, .offset = 24 },
 134 };
 135
 136 static void ipv6_header_init(struct proto_hdr *hdr)
 137 {
 138         proto_lower_default_add(hdr, PROTO_ETH);
 139
 140         proto_header_fields_add(hdr, ipv6_fields, array_size(ipv6_fields));
 141
 142         proto_field_set_default_be32(hdr, IP6_VER, 6);
 143 }
 144
 145 static void ipv6_field_changed(struct proto_field *field)
 146 {
 147         if (field->id == IP6_SADDR || field->id == IP6_DADDR) {
 148                 struct proto_hdr *upper = proto_upper_header(field->hdr);
 149
 150                 if (upper && (upper->ops->id == PROTO_UDP || upper->ops->id == PROTO_TCP))
 151                         upper->is_csum_valid = false;
 152         }
 153 }
 154
 155 #define IPV6_HDR_LEN 40
 156
 157 static void ipv6_packet_finish(struct proto_hdr *hdr)
 158 {
 159         struct packet *pkt = current_packet();
 160         uint16_t total_len = pkt->len - hdr->pkt_offset - IPV6_HDR_LEN;
 161
 162         proto_field_set_default_be16(hdr, IP6_LEN, total_len);
 163         proto_field_set_default_dev_ipv6(hdr, IP6_SADDR);
 164 }
 165
 166 static void ipv6_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
 167 {
 168         uint8_t ip_proto;
 169
 170         switch (pid) {
 171         case PROTO_ICMP6:
 172                 ip_proto = IPPROTO_ICMPV6;
 173                 break;
 174         case PROTO_UDP:
 175                 ip_proto = IPPROTO_UDP;
 176                 break;
 177         case PROTO_TCP:
 178                 ip_proto = IPPROTO_TCP;
 179                 break;
 180         default:
 181                 bug();
 182         }
 183
 184         proto_field_set_default_u8(hdr, IP6_NEXT_HDR, ip_proto);
 185 }
 186
 187 static const struct proto_ops ipv6_proto_ops = {
 188         .id             = PROTO_IP6,
 189         .layer          = PROTO_L3,
 190         .header_init    = ipv6_header_init,
 191         .field_changed  = ipv6_field_changed,
 192         .packet_finish  = ipv6_packet_finish,
 193         .set_next_proto = ipv6_set_next_proto,
 194 };
 195
 196 void protos_l3_init(void)
 197 {
 198         proto_ops_register(&ipv4_proto_ops);
 199         proto_ops_register(&ipv6_proto_ops);
 200 }