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         proto_field_set_default_dev_ipv4(hdr, IP4_SADDR);
  44 }
  45
  46 static void ipv4_field_changed(struct proto_field *field)
  47 {
  48         field->hdr->is_csum_valid = false;
  49 }
  50
  51 static void ipv4_csum_update(struct proto_hdr *hdr)
  52 {
  53         struct packet *pkt;
  54         uint16_t csum;
  55
  56         if (hdr->is_csum_valid)
  57                 return;
  58         if (proto_field_is_set(hdr, IP4_CSUM))
  59                 return;
  60
  61         pkt = packet_get(hdr->pkt_id);
  62
  63         proto_field_set_default_u16(hdr, IP4_CSUM, 0);
  64         csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], hdr->len));
  65         proto_field_set_default_u16(hdr, IP4_CSUM, bswap_16(csum));
  66
  67         hdr->is_csum_valid = true;
  68 }
  69
  70 static void ipv4_packet_finish(struct proto_hdr *hdr)
  71 {
  72         struct packet *pkt = current_packet();
  73         uint16_t total_len;
  74
  75         total_len = pkt->len - hdr->pkt_offset;
  76         proto_field_set_default_be16(hdr, IP4_LEN, total_len);
  77
  78         ipv4_csum_update(hdr);
  79 }
  80
  81 static void ipv4_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  82 {
  83         uint8_t ip_proto;
  84
  85         switch (pid) {
  86         case PROTO_IP4:
  87                 ip_proto = IPPROTO_IPIP;
  88                 break;
  89         case PROTO_IP6:
  90                 ip_proto = IPPROTO_IPV6;
  91                 break;
  92         case PROTO_ICMP4:
  93                 ip_proto = IPPROTO_ICMP;
  94                 break;
  95         case PROTO_UDP:
  96                 ip_proto = IPPROTO_UDP;
  97                 break;
  98         case PROTO_TCP:
  99                 ip_proto = IPPROTO_TCP;
 100                 break;
 101         default:
 102                 bug();
 103         }
 104
 105         proto_field_set_default_u8(hdr, IP4_PROTO, ip_proto);
 106 }
 107
 108 static const struct proto_ops ipv4_proto_ops = {
 109         .id             = PROTO_IP4,
 110         .layer          = PROTO_L3,
 111         .header_init    = ipv4_header_init,
 112         .packet_update  = ipv4_csum_update,
 113         .field_changed  = ipv4_field_changed,
 114         .packet_finish  = ipv4_packet_finish,
 115         .set_next_proto = ipv4_set_next_proto,
 116 };
 117
 118 static struct proto_field ipv6_fields[] = {
 119         { .id = IP6_VER,       .len = 4,  .offset = 0, .shift = 28, .mask = 0xf0000000 },
 120         { .id = IP6_CLASS,     .len = 4,  .offset = 0, .shift = 20, .mask = 0x0ff00000 },
 121         { .id = IP6_FLOW_LBL,  .len = 4,  .offset = 0, .shift = 0,  .mask = 0x000fffff },
 122         { .id = IP6_LEN,       .len = 2,  .offset = 4 },
 123         { .id = IP6_NEXT_HDR,  .len = 1,  .offset = 6 },
 124         { .id = IP6_HOP_LIMIT, .len = 1,  .offset = 7 },
 125         { .id = IP6_SADDR,     .len = 16, .offset = 8 },
 126         { .id = IP6_DADDR,     .len = 16, .offset = 24 },
 127 };
 128
 129 static void ipv6_header_init(struct proto_hdr *hdr)
 130 {
 131         proto_lower_default_add(hdr, PROTO_ETH);
 132
 133         proto_header_fields_add(hdr, ipv6_fields, array_size(ipv6_fields));
 134
 135         proto_field_set_default_be32(hdr, IP6_VER, 6);
 136         proto_field_set_default_dev_ipv6(hdr, IP6_SADDR);
 137 }
 138
 139 #define IPV6_HDR_LEN 40
 140
 141 static void ipv6_packet_finish(struct proto_hdr *hdr)
 142 {
 143         struct packet *pkt = current_packet();
 144         uint16_t total_len = pkt->len - hdr->pkt_offset - IPV6_HDR_LEN;
 145
 146         proto_field_set_default_be16(hdr, IP6_LEN, total_len);
 147 }
 148
 149 static void ipv6_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
 150 {
 151         uint8_t ip_proto;
 152
 153         switch (pid) {
 154         case PROTO_ICMP6:
 155                 ip_proto = IPPROTO_ICMPV6;
 156                 break;
 157         case PROTO_UDP:
 158                 ip_proto = IPPROTO_UDP;
 159                 break;
 160         case PROTO_TCP:
 161                 ip_proto = IPPROTO_TCP;
 162                 break;
 163         default:
 164                 bug();
 165         }
 166
 167         proto_field_set_default_u8(hdr, IP6_NEXT_HDR, ip_proto);
 168 }
 169
 170 static const struct proto_ops ipv6_proto_ops = {
 171         .id             = PROTO_IP6,
 172         .layer          = PROTO_L3,
 173         .header_init    = ipv6_header_init,
 174         .packet_finish  = ipv6_packet_finish,
 175         .set_next_proto = ipv6_set_next_proto,
 176 };
 177
 178 void protos_l3_init(void)
 179 {
 180         proto_ops_register(&ipv4_proto_ops);
 181         proto_ops_register(&ipv6_proto_ops);
 182 }