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_packet_finish(struct proto_hdr *hdr)
  47 {
  48         struct packet *pkt = current_packet();
  49         uint16_t total_len;
  50
  51         total_len = pkt->len - hdr->pkt_offset;
  52         proto_field_set_default_be16(hdr, IP4_LEN, total_len);
  53
  54         if (!proto_field_is_set(hdr, IP4_CSUM)) {
  55                 uint16_t csum;
  56                 uint8_t ihl;
  57
  58                 ihl = proto_field_get_u8(hdr, IP4_IHL);
  59                 csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], ihl * 4));
  60                 proto_field_set_u16(hdr, IP4_CSUM, bswap_16(csum));
  61         }
  62 }
  63
  64 static void ipv4_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  65 {
  66         uint8_t ip_proto;
  67
  68         switch(pid) {
  69         case PROTO_IP4:
  70                 ip_proto = IPPROTO_IPIP;
  71                 break;
  72         case PROTO_UDP:
  73                 ip_proto = IPPROTO_UDP;
  74                 break;
  75         case PROTO_TCP:
  76                 ip_proto = IPPROTO_TCP;
  77                 break;
  78         default:
  79                 bug();
  80         }
  81
  82         proto_field_set_default_u8(hdr, IP4_PROTO, ip_proto);
  83 }
  84
  85 static struct proto_hdr ipv4_hdr = {
  86         .id             = PROTO_IP4,
  87         .layer          = PROTO_L3,
  88         .header_init    = ipv4_header_init,
  89         .packet_finish  = ipv4_packet_finish,
  90         .set_next_proto = ipv4_set_next_proto,
  91 };
  92
  93 static struct proto_field ipv6_fields[] = {
  94         { .id = IP6_VER,       .len = 4,  .offset = 0, .shift = 28, .mask = 0xf0000000 },
  95         { .id = IP6_CLASS,     .len = 4,  .offset = 0, .shift = 20, .mask = 0x0ff00000 },
  96         { .id = IP6_FLOW_LBL,  .len = 4,  .offset = 0, .shift = 0,  .mask = 0x000fffff },
  97         { .id = IP6_LEN,       .len = 2,  .offset = 4 },
  98         { .id = IP6_NEXT_HDR,  .len = 1,  .offset = 6 },
  99         { .id = IP6_HOP_LIMIT, .len = 1,  .offset = 7 },
 100         { .id = IP6_SADDR,     .len = 16, .offset = 8 },
 101         { .id = IP6_DADDR,     .len = 16, .offset = 24 },
 102 };
 103
 104 static void ipv6_header_init(struct proto_hdr *hdr)
 105 {
 106         proto_lower_default_add(hdr, PROTO_ETH);
 107
 108         proto_header_fields_add(hdr, ipv6_fields, array_size(ipv6_fields));
 109
 110         proto_field_set_default_be32(hdr, IP6_VER, 6);
 111         proto_field_set_default_dev_ipv6(hdr, IP6_SADDR);
 112 }
 113
 114 #define IPV6_HDR_LEN 40
 115
 116 static void ipv6_packet_finish(struct proto_hdr *hdr)
 117 {
 118         struct packet *pkt = current_packet();
 119         uint16_t total_len = pkt->len - hdr->pkt_offset - IPV6_HDR_LEN;
 120
 121         proto_field_set_default_be16(hdr, IP6_LEN, total_len);
 122 }
 123
 124 static void ipv6_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
 125 {
 126         uint8_t ip_proto;
 127
 128         switch(pid) {
 129         case PROTO_ICMP6:
 130                 ip_proto = IPPROTO_ICMPV6;
 131                 break;
 132         case PROTO_UDP:
 133                 ip_proto = IPPROTO_UDP;
 134                 break;
 135         case PROTO_TCP:
 136                 ip_proto = IPPROTO_TCP;
 137                 break;
 138         default:
 139                 bug();
 140         }
 141
 142         proto_field_set_default_u8(hdr, IP6_NEXT_HDR, ip_proto);
 143 }
 144
 145 static struct proto_hdr ipv6_hdr = {
 146         .id             = PROTO_IP6,
 147         .layer          = PROTO_L3,
 148         .header_init    = ipv6_header_init,
 149         .packet_finish  = ipv6_packet_finish,
 150         .set_next_proto = ipv6_set_next_proto,
 151 };
 152
 153 void protos_l3_init(void)
 154 {
 155         proto_header_register(&ipv4_hdr);
 156         proto_header_register(&ipv6_hdr);
 157 }