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/*
* netsniff-ng - the packet sniffing beast
* Subject to the GPL, version 2.
*/
#include <linux/if_ether.h>
#include "die.h"
#include "csum.h"
#include "built_in.h"
#include "trafgen_l2.h"
#include "trafgen_l3.h"
#include "trafgen_proto.h"
#include "trafgen_conf.h"
static struct proto_field ipv4_fields[] = {
{ .id = IP4_VER, .len = 1, .offset = 0, .shift = 4, .mask = 0xf0 },
{ .id = IP4_IHL, .len = 1, .offset = 0, .shift = 0, .mask = 0x0f },
{ .id = IP4_DSCP, .len = 1, .offset = 1, .shift = 2, .mask = 0xfc },
{ .id = IP4_ECN, .len = 1, .offset = 1, .shift = 0, .mask = 0x03 },
{ .id = IP4_TOS, .len = 1, .offset = 1 },
{ .id = IP4_LEN, .len = 2, .offset = 2 },
{ .id = IP4_ID, .len = 2, .offset = 4 },
{ .id = IP4_FLAGS, .len = 2, .offset = 6, .shift = 13, .mask = 0xe000 },
{ .id = IP4_MF, .len = 2, .offset = 6, .shift = 13, .mask = 0x2000 },
{ .id = IP4_DF, .len = 2, .offset = 6, .shift = 14, .mask = 0x4000 },
{ .id = IP4_FRAG_OFFS, .len = 2, .offset = 6, .shift = 0, .mask = 0x1fff },
{ .id = IP4_TTL, .len = 1, .offset = 8 },
{ .id = IP4_PROTO, .len = 1, .offset = 9 },
{ .id = IP4_CSUM, .len = 2, .offset = 10 },
{ .id = IP4_SADDR, .len = 4, .offset = 12 },
{ .id = IP4_DADDR, .len = 4, .offset = 16 },
};
static void ipv4_header_init(struct proto_hdr *hdr)
{
proto_lower_default_add(hdr, PROTO_ETH);
proto_header_fields_add(hdr, ipv4_fields, array_size(ipv4_fields));
proto_field_set_default_u8(hdr, IP4_VER, 4);
proto_field_set_default_u8(hdr, IP4_IHL, 5);
proto_field_set_default_dev_ipv4(hdr, IP4_SADDR);
}
static void ipv4_packet_finish(struct proto_hdr *hdr)
{
struct packet *pkt = current_packet();
uint16_t total_len;
total_len = pkt->len - hdr->pkt_offset;
proto_field_set_default_be16(hdr, IP4_LEN, total_len);
if (!proto_field_is_set(hdr, IP4_CSUM)) {
uint16_t csum;
uint8_t ihl;
ihl = proto_field_get_u8(hdr, IP4_IHL);
csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], ihl * 4));
proto_field_set_u16(hdr, IP4_CSUM, bswap_16(csum));
}
}
static void ipv4_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
{
uint8_t ip_proto;
switch(pid) {
case PROTO_IP4:
ip_proto = IPPROTO_IPIP;
break;
case PROTO_UDP:
ip_proto = IPPROTO_UDP;
break;
case PROTO_TCP:
ip_proto = IPPROTO_TCP;
break;
default:
bug();
}
proto_field_set_default_u8(hdr, IP4_PROTO, ip_proto);
}
static struct proto_hdr ipv4_hdr = {
.id = PROTO_IP4,
.layer = PROTO_L3,
.header_init = ipv4_header_init,
.packet_finish = ipv4_packet_finish,
.set_next_proto = ipv4_set_next_proto,
};
void protos_l3_init(void)
{
proto_header_register(&ipv4_hdr);
}
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