resend.c revision 72003 
1/*
2 * resend.c (C) 1995-1998 Darren Reed
3 *
4 * This was written to test what size TCP fragments would get through
5 * various TCP/IP packet filters, as used in IP firewalls.  In certain
6 * conditions, enough of the TCP header is missing for unpredictable
7 * results unless the filter is aware that this can happen.
8 *
9 * Redistribution and use in source and binary forms are permitted
10 * provided that this notice is preserved and due credit is given
11 * to the original author and the contributors.
12 */
13#if !defined(lint)
14static const char sccsid[] = "@(#)resend.c	1.3 1/11/96 (C)1995 Darren Reed";
15static const char rcsid[] = "@(#)$Id: resend.c,v 2.1.4.1 2001/01/10 06:21:20 darrenr Exp $";
16#endif
17#include <stdio.h>
18#include <netdb.h>
19#include <string.h>
20#include <stdlib.h>
21#include <unistd.h>
22#include <sys/types.h>
23#include <sys/time.h>
24#include <sys/socket.h>
25#include <net/if.h>
26#include <netinet/in.h>
27#include <arpa/inet.h>
28#include <netinet/in_systm.h>
29#include <netinet/ip.h>
30#include <netinet/tcp.h>
31#include <netinet/udp.h>
32#include <netinet/ip_icmp.h>
33#ifndef	linux
34# include <netinet/ip_var.h>
35# include <netinet/if_ether.h>
36# if __FreeBSD_version >= 300000
37#  include <net/if_var.h>
38# endif
39#endif
40#include "ipsend.h"
41
42extern	int	opts;
43
44static	u_char	pbuf[65536];	/* 1 big packet */
45void	printpacket __P((ip_t *));
46
47
48void printpacket(ip)
49ip_t	*ip;
50{
51	tcphdr_t *t;
52	int i, j;
53
54	t = (tcphdr_t *)((char *)ip + (ip->ip_hl << 2));
55	if (ip->ip_tos)
56		printf("tos %#x ", ip->ip_tos);
57	if (ip->ip_off & 0x3fff)
58		printf("frag @%#x ", (ip->ip_off & 0x1fff) << 3);
59	printf("len %d id %d ", ip->ip_len, ip->ip_id);
60	printf("ttl %d p %d src %s", ip->ip_ttl, ip->ip_p,
61		inet_ntoa(ip->ip_src));
62	if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_UDP)
63		printf(",%d", t->th_sport);
64	printf(" dst %s", inet_ntoa(ip->ip_dst));
65	if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_UDP)
66		printf(",%d", t->th_dport);
67	if (ip->ip_p == IPPROTO_TCP) {
68		printf(" seq %lu:%lu flags ",
69			(u_long)t->th_seq, (u_long)t->th_ack);
70		for (j = 0, i = 1; i < 256; i *= 2, j++)
71			if (t->th_flags & i)
72				printf("%c", "FSRPAU--"[j]);
73	}
74	putchar('\n');
75}
76
77
78int	ip_resend(dev, mtu, r, gwip, datain)
79char	*dev;
80int	mtu;
81struct	in_addr	gwip;
82struct	ipread	*r;
83char	*datain;
84{
85	ether_header_t	*eh;
86	char	dhost[6];
87	ip_t	*ip;
88	int	fd, wfd = initdevice(dev, 0, 5), len, i;
89
90	if (datain)
91		fd = (*r->r_open)(datain);
92	else
93		fd = (*r->r_open)("-");
94
95	if (fd < 0)
96		exit(-1);
97
98	ip = (struct ip *)pbuf;
99	eh = (ether_header_t *)malloc(sizeof(*eh));
100	if(!eh)
101	    {
102		perror("malloc failed");
103		return -2;
104	    }
105
106	bzero((char *)A_A eh->ether_shost, sizeof(eh->ether_shost));
107	if (gwip.s_addr && (arp((char *)&gwip, dhost) == -1))
108	    {
109		perror("arp");
110		return -2;
111	    }
112
113	while ((i = (*r->r_readip)((char *)pbuf, sizeof(pbuf), NULL, NULL)) > 0)
114	    {
115		if (!(opts & OPT_RAW)) {
116			len = ntohs(ip->ip_len);
117			eh = (ether_header_t *)realloc((char *)eh, sizeof(*eh) + len);
118			eh->ether_type = htons((u_short)ETHERTYPE_IP);
119			if (!gwip.s_addr) {
120				if (arp((char *)&gwip,
121					(char *)A_A eh->ether_dhost) == -1) {
122					perror("arp");
123					continue;
124				}
125			} else
126				bcopy(dhost, (char *)A_A eh->ether_dhost,
127				      sizeof(dhost));
128			if (!ip->ip_sum)
129				ip->ip_sum = chksum((u_short *)ip,
130						    ip->ip_hl << 2);
131			bcopy(ip, (char *)(eh + 1), len);
132			len += sizeof(*eh);
133			printpacket(ip);
134		} else {
135			eh = (ether_header_t *)pbuf;
136			len = i;
137		}
138
139		if (sendip(wfd, (char *)eh, len) == -1)
140		    {
141			perror("send_packet");
142			break;
143		    }
144	    }
145	(*r->r_close)();
146	return 0;
147}
148