1/*	$FreeBSD: stable/11/contrib/ipfilter/lib/ipft_pc.c 369245 2021-02-09 13:47:46Z git2svn $	*/
2
3/*
4 * Copyright (C) 2012 by Darren Reed.
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * $Id$
9 */
10#include "ipf.h"
11#include "ipt.h"
12
13#if !defined(lint)
14static const char rcsid[] = "@(#)$Id$";
15#endif
16
17struct	llc	{
18	int	lc_type;
19	int	lc_sz;	/* LLC header length */
20	int	lc_to;	/* LLC Type offset */
21	int	lc_tl;	/* LLC Type length */
22};
23
24/*
25 * While many of these maybe the same, some do have different header formats
26 * which make this useful.
27 */
28
29static	struct	llc	llcs[] = {
30	{ 0, 0, 0, 0 },				/* DLT_NULL */
31	{ 1, 14, 12, 2 },			/* DLT_Ethernet */
32	{ 10, 0, 0, 0 },			/* DLT_FDDI */
33	{ 12, 0, 0, 0 },			/* DLT_RAW */
34	{ -1, -1, -1, -1 }
35};
36
37typedef struct {
38	u_int	id;
39	u_short	major;
40	u_short	minor;
41	u_int	timezone;
42	u_int	sigfigs;
43	u_int	snaplen;
44	u_int	type;
45} fileheader_t;
46
47typedef struct {
48	u_32_t	seconds;
49	u_32_t	microseconds;
50	u_32_t	caplen;
51	u_32_t	wirelen;
52} packetheader_t;
53
54static	int	ipcap_open(char *);
55static	int	ipcap_close(void);
56static	int	ipcap_readip(mb_t *, char **, int *);
57static	int	ipcap_read_rec(packetheader_t *);
58static	void	iswap_hdr(fileheader_t *);
59
60static	int	pfd = -1, swapped = 0;
61static	struct llc	*llcp = NULL;
62
63struct	ipread	pcap = { ipcap_open, ipcap_close, ipcap_readip, 0 };
64
65#define	SWAPLONG(y)	\
66	((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
67#define	SWAPSHORT(y)	\
68	( (((y)&0xff)<<8) | (((y)&0xff00)>>8) )
69
70static	void	iswap_hdr(p)
71	fileheader_t	*p;
72{
73	p->major = SWAPSHORT(p->major);
74	p->minor = SWAPSHORT(p->minor);
75	p->timezone = SWAPLONG(p->timezone);
76	p->sigfigs = SWAPLONG(p->sigfigs);
77	p->snaplen = SWAPLONG(p->snaplen);
78	p->type = SWAPLONG(p->type);
79}
80
81static	int	ipcap_open(fname)
82	char	*fname;
83{
84	fileheader_t ph;
85	int fd, i;
86
87	if (pfd != -1)
88		return pfd;
89
90	if (!strcmp(fname, "-"))
91		fd = 0;
92	else if ((fd = open(fname, O_RDONLY)) == -1)
93		return -1;
94
95	if (read(fd, (char *)&ph, sizeof(ph)) != sizeof(ph))
96		return -2;
97
98	if (ph.id != 0xa1b2c3d4) {
99		if (SWAPLONG(ph.id) != 0xa1b2c3d4) {
100			(void) close(fd);
101			return -2;
102		}
103		swapped = 1;
104		iswap_hdr(&ph);
105	}
106
107	for (i = 0; llcs[i].lc_type != -1; i++)
108		if (llcs[i].lc_type == ph.type) {
109			llcp = llcs + i;
110			break;
111		}
112
113	if (llcp == NULL) {
114		(void) close(fd);
115		return -2;
116	}
117
118	pfd = fd;
119	printf("opened pcap file %s:\n", fname);
120	printf("\tid: %08x version: %d.%d type: %d snap %d\n",
121		ph.id, ph.major, ph.minor, ph.type, ph.snaplen);
122
123	return fd;
124}
125
126
127static	int	ipcap_close()
128{
129	return close(pfd);
130}
131
132
133/*
134 * read in the header (and validate) which should be the first record
135 * in a pcap file.
136 */
137static	int	ipcap_read_rec(rec)
138	packetheader_t *rec;
139{
140	int	n, p, i;
141	char	*s;
142
143	s = (char *)rec;
144	n = sizeof(*rec);
145
146	while (n > 0) {
147		i = read(pfd, (char *)rec, sizeof(*rec));
148		if (i <= 0)
149			return -2;
150		s += i;
151		n -= i;
152	}
153
154	if (swapped) {
155		rec->caplen = SWAPLONG(rec->caplen);
156		rec->wirelen = SWAPLONG(rec->wirelen);
157		rec->seconds = SWAPLONG(rec->seconds);
158		rec->microseconds = SWAPLONG(rec->microseconds);
159	}
160	p = rec->caplen;
161	n = MIN(p, rec->wirelen);
162	if (!n || n < 0)
163		return -3;
164
165	if (p < 0 || p > 65536)
166		return -4;
167	return p;
168}
169
170
171#ifdef	notyet
172/*
173 * read an entire pcap packet record.  only the data part is copied into
174 * the available buffer, with the number of bytes copied returned.
175 */
176static	int	ipcap_read(buf, cnt)
177	char	*buf;
178	int	cnt;
179{
180	packetheader_t rec;
181	static	char	*bufp = NULL;
182	int	i, n;
183
184	if ((i = ipcap_read_rec(&rec)) <= 0)
185		return i;
186
187	if (!bufp)
188		bufp = malloc(i);
189	else
190		bufp = realloc(bufp, i);
191
192	if (read(pfd, bufp, i) != i)
193		return -2;
194
195	n = MIN(i, cnt);
196	bcopy(bufp, buf, n);
197	return n;
198}
199#endif
200
201
202/*
203 * return only an IP packet read into buf
204 */
205static	int	ipcap_readip(mb, ifn, dir)
206	mb_t	*mb;
207	char	**ifn;
208	int	*dir;
209{
210	static	char	*bufp = NULL;
211	packetheader_t	rec;
212	struct	llc	*l;
213	char	*s, ty[4];
214	int	i, j, n;
215	char	*buf;
216	int	cnt;
217
218#if 0
219	ifn = ifn;	/* gcc -Wextra */
220	dir = dir;	/* gcc -Wextra */
221#endif
222	buf = (char *)mb->mb_buf;
223	cnt = sizeof(mb->mb_buf);
224	l = llcp;
225
226	/* do { */
227		if ((i = ipcap_read_rec(&rec)) <= 0)
228			return i;
229
230		if (!bufp)
231			bufp = malloc(i);
232		else
233			bufp = realloc(bufp, i);
234		s = bufp;
235
236		for (j = i, n = 0; j > 0; ) {
237			n = read(pfd, s, j);
238			if (n <= 0)
239				return -2;
240			j -= n;
241			s += n;
242		}
243		s = bufp;
244
245		i -= l->lc_sz;
246		s += l->lc_to;
247		bcopy(s, ty, l->lc_tl);
248		s += l->lc_tl;
249	/* } while (ty[0] != 0x8 && ty[1] != 0); */
250	n = MIN(i, cnt);
251	bcopy(s, buf, n);
252	mb->mb_len = n;
253	return n;
254}
255