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/*
* netsniff-ng - the packet sniffing beast
* Subject to the GPL, version 2.
*/
#include <stdbool.h>
#include <netinet/in.h>
#include "die.h"
#include "csum.h"
#include "built_in.h"
#include "trafgen_l3.h"
#include "trafgen_l4.h"
#include "trafgen_conf.h"
#include "trafgen_proto.h"
static struct proto_field udp_fields[] = {
{ .id = UDP_SPORT, .len = 2, .offset = 0 },
{ .id = UDP_DPORT, .len = 2, .offset = 2 },
{ .id = UDP_LEN, .len = 2, .offset = 4 },
{ .id = UDP_CSUM, .len = 2, .offset = 6 },
};
static void udp_header_init(struct proto_hdr *hdr)
{
struct proto_hdr *lower;
proto_lower_default_add(PROTO_IP4);
lower = proto_current_header();
if (lower->id == PROTO_IP4)
proto_field_set_default_u8(lower, IP4_PROTO, IPPROTO_UDP);
proto_header_fields_add(hdr, udp_fields, array_size(udp_fields));
}
static void udp_packet_finish(struct proto_hdr *hdr)
{
struct proto_hdr *lower = proto_lower_header(hdr);
struct packet *pkt = current_packet();
uint16_t total_len;
uint16_t csum;
total_len = pkt->len - hdr->pkt_offset;
proto_field_set_default_be16(hdr, UDP_LEN, total_len);
if (proto_field_is_set(hdr, UDP_CSUM))
return;
if (!lower || lower->id != PROTO_IP4)
return;
total_len = proto_field_get_u16(hdr, UDP_LEN);
csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
total_len, IPPROTO_UDP);
proto_field_set_be16(hdr, UDP_CSUM, bswap_16(csum));
}
static struct proto_hdr udp_hdr = {
.id = PROTO_UDP,
.layer = PROTO_L4,
.header_init = udp_header_init,
.packet_finish = udp_packet_finish,
};
void protos_l4_init(void)
{
proto_header_register(&udp_hdr);
}
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