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/* $Id: udp_probe.c,v 1.9 2001/10/20 15:23:55 fygrave Exp $ */
/*
** Copyright (C) 2001 Fyodor Yarochkin <fygrave@tigerteam.net>,
** Ofir Arkin <ofir@sys-security.com>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** All material for nonprofit, educational use only.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "xprobe.h"
/*
packet validation correctness is done within the query sending routine.
NULL is returned if packet is not valid
caller has to free() retval->pkt and retval when done (otherwise memory
leak will occur).
*/
rpack_t *send_udp(struct sockaddr_in to) {
int sndsock;
int res;
int port;
struct ip *ip;
struct udphdr *udp;
unsigned char *pack, *recv_pack;
int on = 1;
int packlen;
rpack_t *retval = NULL;
if ((port = udp_find_closed(to)) < 0) {
fprintf(stderr, "failed to find any closed UDP port.\n");
exit(1);
}
if ((sndsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0) {
perror("Can not open raw socket:");
exit(1);
}
if (setsockopt(sndsock, IPPROTO_IP, IP_HDRINCL, (char *)&on,
sizeof(on)) < 0) {
perror("IP_HDRINCL");
exit(1);
}
packlen = sizeof(struct ip) + sizeof(struct udphdr) + UDP_DATA_SIZE;
if((pack = (unsigned char *)calloc( packlen, 1)) == NULL) {
perror("calloc");
exit(1);
}
ip = (struct ip *)pack;
udp = (struct udphdr *)(pack + sizeof(struct ip));
make_ippkt(ip, IPPROTO_UDP, interf.addr, to.sin_addr,
packlen, IP_DF, 0);
udp->uh_sport = htons(rand());
udp->uh_dport = htons(port);
udp->uh_ulen = htons((unsigned short) packlen - sizeof(struct ip));
udp->uh_sum = udp_cksum_calc(ip, udp, sizeof(struct udphdr) +
UDP_DATA_SIZE);
log_message("[send]-> UDP to %s:%i ", inet_ntoa(to.sin_addr)
, port);
res = sendto(sndsock, (void *)pack, packlen,
0, (struct sockaddr *)&to, sizeof(struct sockaddr));
if (res <0) {
perror("sendto:");
close(sndsock);
free(pack);
return NULL;
}
log_message("[%d bytes] sent, waiting for response.", res);
recv_pack = read_icmp(&res, ICMP_UNREACH, -1);
if (recv_pack == NULL || res < sizeof(ip) + 8) {
fprintf(stderr,"Receive timeout. Quitting..\n");
close(sndsock);
free(pack);
return NULL;
}
if ((retval=calloc(sizeof(rpack_t), 1)) == NULL) {
perror("calloc");
exit(1);
}
retval->packsize = res;
if((retval->pkt = calloc(res, 1)) == NULL) {
perror("calloc");
exit(1);
}
memcpy((void *)retval->pkt, (void *)recv_pack, res);
#ifdef DEBUG
fprintf(stderr,"Received %d bytes packet.\n", res);
hexdump(recv_pack, res);
fprintf(stderr,"\n----\n");
hexdump(retval->pkt, res);
#endif
retval->ip = (struct ip *)retval->pkt;
/* sanity checks */
#ifdef DEBUG
fprintf(stderr, "hlen: %d\nlen: %d\n", retval->ip->ip_hl<<2, htons(retval->ip->ip_len));
#endif
if (res < sizeof(struct ip) ||
(retval->ip->ip_hl << 2) > res ||
ntohs(retval->ip->ip_len) > res ) {
fprintf(stderr,"Received maliformed packet!\n");
close(sndsock);
free(pack);
free(retval->pkt);
free(retval);
return NULL;
}
retval->icmp = (struct icmp *)((VOIDPTR_T)retval->pkt + (VOIDPTR_T)(retval->ip->ip_hl<<2));
#ifdef DEBUG
fprintf(stderr,"type: %d code: %d\n", retval->icmp->icmp_type, retval->icmp->icmp_code);
#endif
retval->orig_pkt = pack;
retval->orig_ip = (struct ip *)pack;
close(sndsock);
return retval;
}
int udp_find_closed(struct sockaddr_in to) {
if (udp_portno) return udp_portno;
return UDP_PORT; /* lets stick with defines for the moment */
}
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