1/*-
2 * Copyright (c) 2006, Andrea Bittau <a.bittau@cs.ucl.ac.uk>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26#include <sys/uio.h>
27#include <sys/types.h>
28#include <sys/socket.h>
29#include <netinet/in_systm.h>
30#include <netinet/in.h>
31#include <arpa/inet.h>
32#include <netinet/ip.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37#include <fcntl.h>
38#include <errno.h>
39#include <signal.h>
40#include <err.h>
41
42void hexdump(void *b, int len)
43{
44        unsigned char *p = (unsigned char*) b;
45
46        while (len--)
47                printf("%.2X ", *p++);
48        printf("\n");
49}
50
51int handle_data(int dude, char *buf, int len)
52{
53	struct ip *ih;
54	unsigned short id;
55	char tmp[4];
56	struct iovec iov[2];
57	struct msghdr mh;
58
59	ih = (struct ip*) buf;
60
61	/* XXX IP FRAGS */
62
63	/* filter */
64	if (ih->ip_p != 0)
65		return 0;
66
67	if (ih->ip_hl != 5)
68		return 0;
69
70	/* get info */
71	id = ih->ip_id;
72	len -= 20;
73	buf += 20;
74	printf("Got %d bytes [%d]\n", len, ntohs(id));
75#if 0
76	hexdump(buf, len);
77#endif
78
79	/* prepare packet */
80	memcpy(tmp, &id, 2);
81	id = htons(len);
82	memcpy(&tmp[2], &id, 2);
83
84	iov[0].iov_base = tmp;
85	iov[0].iov_len = 4;
86	iov[1].iov_base = buf;
87	iov[1].iov_len = len;
88
89	memset(&mh, 0, sizeof(mh));
90	mh.msg_iov = iov;
91	mh.msg_iovlen = sizeof(iov)/sizeof(struct iovec);
92
93	/* write */
94	if (sendmsg(dude, &mh, 0) != (4 + len))
95		return -1;
96	return 0;
97}
98
99void handle_dude(int dude, int raw)
100{
101	char buf[4096];
102	int rd;
103
104	while (1) {
105		rd = recv(raw, buf, sizeof(buf), 0);
106		if (rd == -1)
107			err(1, "recv()");
108
109		if (handle_data(dude, buf, rd) == -1)
110			return;
111	}
112}
113
114void hand(int s)
115{
116	printf("sigpipe\n");
117}
118
119int main(int argc, char *argv[])
120{
121	int s, dude;
122	struct sockaddr_in s_in;
123	int len;
124	int raw;
125
126	memset(&s_in, 0, sizeof(s_in));
127	s_in.sin_family = PF_INET;
128	s_in.sin_port = htons(666);
129	s_in.sin_addr.s_addr = INADDR_ANY;
130
131	if ((raw = socket(PF_INET, SOCK_RAW, 0)) == -1)
132		err(1, "socket()");
133
134	if ((s = socket(s_in.sin_family, SOCK_STREAM, IPPROTO_TCP)) == -1)
135		err(1, "socket()");
136
137	if (bind(s, (struct sockaddr*)&s_in, sizeof(s_in)) == -1)
138		err(1, "bind()");
139
140	if (listen(s, 5) == -1)
141		err(1, "listen()");
142
143	if (signal(SIGPIPE, hand) == SIG_ERR)
144		err(1, "signal()");
145
146	while (1) {
147		len = sizeof(s_in);
148		dude = accept(s, (struct sockaddr*)&s_in, &len);
149		if (dude == -1)
150			err(1, "accept()");
151
152		printf("Got dude %s\n", inet_ntoa(s_in.sin_addr));
153		handle_dude(dude, raw);
154		printf("Done\n");
155	}
156}
157