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/****************************************************************************
** File: udp.c
**
** Author: Mike Borella
**
** Comments: Dump UDP header information
**
*****************************************************************************/
#include <stdio.h>
#include <unistd.h>
#include <arpa/inet.h>
#include "config.h"
#include "udp.h"
extern u_char *packet_end;
extern struct arg_t *my_args;
/*----------------------------------------------------------------------------
**
** dump_udp()
**
** Parse UDP header and dump fields
**
**----------------------------------------------------------------------------
*/
void dump_udp(u_char *bp, int length)
{
UDPHdr *up;
u_char *ep = bp + length;
u_short sport, dport, len;
char *udpport_string(u_short);
void dump_payload(u_char *, int);
/*
* Make sure we don't run off the end of the packet
*/
if (ep > packet_end) ep = packet_end;
/*
* Check for truncated packet
*/
if (length < sizeof(UDPHdr))
{
printf("Truncated header, length = %d bytes\n", length);
return;
}
up = (UDPHdr *) bp;
sport = ntohs(up->uh_src);
dport = ntohs(up->uh_dst);
len = ntohs(up->uh_len);
/*
* Dump UDP header info
*/
printf("----------------------------------------------------------\n");
printf(" UDP Header\n");
printf("----------------------------------------------------------\n");
if (!my_args->t)
{
printf("Source port: %d", sport);
if (sport < 1024)
printf(" (%s)\n", udpport_string(sport));
else
printf("\n");
printf("Destination port: %d", dport);
if (dport < 1024)
printf(" (%s)\n", udpport_string(dport));
else
printf("\n");
printf("Length: %d\n", len*4);
printf("Checksum: %d\n", ntohs(up->uh_chk));
}
/*
* print payload if there is one
*/
if (my_args->p && len > 0)
dump_payload((u_char *) bp + sizeof(UDPHdr), len);
return;
}
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