trafgen_l4.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Subject to the GPL, version 2.
   4  */
   5
   6 #include <stdbool.h>
   7 #include <netinet/in.h>
   8
   9 #include "die.h"
  10 #include "csum.h"
  11 #include "built_in.h"
  12 #include "trafgen_l3.h"
  13 #include "trafgen_l4.h"
  14 #include "trafgen_conf.h"
  15 #include "trafgen_proto.h"
  16
  17 static struct proto_field udp_fields[] = {
  18         { .id = UDP_SPORT, .len = 2, .offset = 0 },
  19         { .id = UDP_DPORT, .len = 2, .offset = 2 },
  20         { .id = UDP_LEN,   .len = 2, .offset = 4 },
  21         { .id = UDP_CSUM,  .len = 2, .offset = 6 },
  22 };
  23
  24 static void udp_header_init(struct proto_hdr *hdr)
  25 {
  26         proto_lower_default_add(hdr, PROTO_IP4);
  27
  28         proto_header_fields_add(hdr, udp_fields, array_size(udp_fields));
  29 }
  30
  31 static void udp_packet_finish(struct proto_hdr *hdr)
  32 {
  33         struct proto_hdr *lower = proto_lower_header(hdr);
  34         struct packet *pkt = current_packet();
  35         uint16_t total_len;
  36         uint16_t csum;
  37
  38         total_len = pkt->len - hdr->pkt_offset;
  39         proto_field_set_default_be16(hdr, UDP_LEN, total_len);
  40
  41         if (proto_field_is_set(hdr, UDP_CSUM))
  42                 return;
  43
  44         if (!lower)
  45                 return;
  46
  47         total_len = proto_field_get_u16(hdr, UDP_LEN);
  48
  49         switch (lower->id) {
  50         case PROTO_IP4:
  51                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
  52                                 total_len, IPPROTO_UDP);
  53                 break;
  54         case PROTO_IP6:
  55                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
  56                                 total_len, IPPROTO_UDP);
  57                 break;
  58         default:
  59                 csum = 0;
  60                 break;
  61         }
  62
  63         proto_field_set_be16(hdr, UDP_CSUM, bswap_16(csum));
  64 }
  65
  66 static struct proto_hdr udp_hdr = {
  67         .id             = PROTO_UDP,
  68         .layer          = PROTO_L4,
  69         .header_init    = udp_header_init,
  70         .packet_finish  = udp_packet_finish,
  71 };
  72
  73 static struct proto_field tcp_fields[] = {
  74         { .id = TCP_SPORT,   .len = 2, .offset = 0 },
  75         { .id = TCP_DPORT,   .len = 2, .offset = 2 },
  76         { .id = TCP_SEQ,     .len = 4, .offset = 4 },
  77         { .id = TCP_ACK_SEQ, .len = 4, .offset = 8 },
  78         { .id = TCP_DOFF,    .len = 2, .offset = 12, .shift = 12, .mask = 0xf000 },
  79         /* reserved (4 bits) */
  80         { .id = TCP_CWR,     .len = 2, .offset = 12, .shift = 7, .mask = 0x0080 },
  81         { .id = TCP_ECE,     .len = 2, .offset = 12, .shift = 6, .mask = 0x0040 },
  82         { .id = TCP_URG,     .len = 2, .offset = 12, .shift = 5, .mask = 0x0020 },
  83         { .id = TCP_ACK,     .len = 2, .offset = 12, .shift = 4, .mask = 0x0010 },
  84         { .id = TCP_PSH,     .len = 2, .offset = 12, .shift = 3, .mask = 0x0008 },
  85         { .id = TCP_RST,     .len = 2, .offset = 12, .shift = 2, .mask = 0x0004 },
  86         { .id = TCP_SYN,     .len = 2, .offset = 12, .shift = 1, .mask = 0x0002 },
  87         { .id = TCP_FIN,     .len = 2, .offset = 12, .shift = 0, .mask = 0x0001 },
  88         { .id = TCP_WINDOW,  .len = 2, .offset = 14 },
  89         { .id = TCP_CSUM,    .len = 2, .offset = 16 },
  90         { .id = TCP_URG_PTR, .len = 2, .offset = 18 },
  91 };
  92
  93 static void tcp_header_init(struct proto_hdr *hdr)
  94 {
  95         proto_lower_default_add(hdr, PROTO_IP4);
  96
  97         proto_header_fields_add(hdr, tcp_fields, array_size(tcp_fields));
  98
  99         proto_field_set_default_be16(hdr, TCP_DOFF, 5);
 100 }
 101
 102 static void tcp_packet_finish(struct proto_hdr *hdr)
 103 {
 104         struct proto_hdr *lower = proto_lower_header(hdr);
 105         struct packet *pkt = current_packet();
 106         uint16_t total_len;
 107         uint16_t csum;
 108
 109         if (proto_field_is_set(hdr, TCP_CSUM))
 110                 return;
 111
 112         if (!lower)
 113                 return;
 114
 115         total_len = pkt->len - hdr->pkt_offset;
 116
 117         switch (lower->id) {
 118         case PROTO_IP4:
 119                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 120                                 total_len, IPPROTO_TCP);
 121                 break;
 122         case PROTO_IP6:
 123                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 124                                 total_len, IPPROTO_TCP);
 125                 break;
 126         default:
 127                 csum = 0;
 128                 break;
 129         }
 130
 131         proto_field_set_be16(hdr, TCP_CSUM, bswap_16(csum));
 132 }
 133
 134 static struct proto_hdr tcp_hdr = {
 135         .id             = PROTO_TCP,
 136         .layer          = PROTO_L4,
 137         .header_init    = tcp_header_init,
 138         .packet_finish  = tcp_packet_finish,
 139 };
 140
 141 static struct proto_field icmpv6_fields[] = {
 142         { .id = ICMPV6_TYPE, .len = 1, .offset = 0 },
 143         { .id = ICMPV6_CODE, .len = 1, .offset = 1 },
 144         { .id = ICMPV6_CSUM, .len = 2, .offset = 2 }
 145 };
 146
 147 static void icmpv6_header_init(struct proto_hdr *hdr)
 148 {
 149         proto_lower_default_add(hdr, PROTO_IP6);
 150
 151         proto_header_fields_add(hdr, icmpv6_fields, array_size(icmpv6_fields));
 152 }
 153
 154 static void icmpv6_packet_finish(struct proto_hdr *hdr)
 155 {
 156         struct proto_hdr *lower = proto_lower_header(hdr);
 157         struct packet *pkt = current_packet();
 158         uint16_t total_len;
 159         uint16_t csum;
 160
 161         if (proto_field_is_set(hdr, ICMPV6_CSUM))
 162                 return;
 163
 164         if (!lower)
 165                 return;
 166
 167         total_len = pkt->len - hdr->pkt_offset;
 168
 169         switch (lower->id) {
 170         case PROTO_IP6:
 171                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 172                                 total_len, IPPROTO_ICMPV6);
 173                 break;
 174         default:
 175                 csum = 0;
 176                 break;
 177         }
 178
 179         proto_field_set_be16(hdr, ICMPV6_CSUM, bswap_16(csum));
 180 }
 181
 182 static struct proto_hdr icmpv6_hdr = {
 183         .id             = PROTO_ICMP6,
 184         .layer          = PROTO_L4,
 185         .header_init    = icmpv6_header_init,
 186         .packet_finish  = icmpv6_packet_finish,
 187 };
 188
 189 void protos_l4_init(void)
 190 {
 191         proto_header_register(&udp_hdr);
 192         proto_header_register(&tcp_hdr);
 193         proto_header_register(&icmpv6_hdr);
 194 }