pcap-linux.c revision 26175 
1/*
2 * Copyright (c) 1996
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 */
21#ifndef lint
22static const char rcsid[] =
23    "@(#) $Header: pcap-linux.c,v 1.4 96/12/10 23:15:00 leres Exp $ (LBL)";
24#endif
25
26#include <sys/param.h>
27#include <sys/ioctl.h>
28#include <sys/socket.h>
29#include <sys/time.h>
30
31#include <net/if.h>
32
33#include <netinet/in.h>
34
35#include <errno.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include <string.h>
39#include <unistd.h>
40
41static struct ifreq saved_ifr;
42
43#include "pcap-int.h"
44
45#include "gnuc.h"
46#ifdef HAVE_OS_PROTO_H
47#include "os-proto.h"
48#endif
49
50void linux_restore_ifr(void);
51
52int
53pcap_stats(pcap_t *p, struct pcap_stat *ps)
54{
55
56	*ps = p->md.stat;
57	return (0);
58}
59
60int
61pcap_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
62{
63	register int cc;
64	register int bufsize;
65	register int caplen;
66	register u_char *bp;
67	struct sockaddr from;
68	int fromlen;
69
70	bp = (char *)p->buffer;
71	bufsize = p->bufsize;
72	if (p->md.pad > 0) {
73		bp += p->md.pad;
74		bufsize -= p->md.pad;
75		memset(p->buffer, 0, p->md.pad);
76	}
77
78again:
79	do {
80		fromlen = sizeof(from);
81		cc = recvfrom(p->fd, bp, bufsize, 0, &from, &fromlen);
82		if (cc < 0) {
83			/* Don't choke when we get ptraced */
84			switch (errno) {
85
86			case EINTR:
87					goto again;
88
89			case EWOULDBLOCK:
90				return (0);		/* XXX */
91			}
92			sprintf(p->errbuf, "read: %s", pcap_strerror(errno));
93			return (-1);
94		}
95	} while (strcmp(p->md.device, from.sa_data));
96
97	/* If we need have leading zero bytes, adjust count */
98	cc += p->md.pad;
99	bp = p->buffer;
100
101	/* If we need to step over leading junk, adjust count and pointer */
102	cc -= p->md.skip;
103	bp += p->md.skip;
104
105	/* Captured length can't exceed our read buffer size */
106	caplen = cc;
107	if (caplen > bufsize)
108		caplen = bufsize;
109
110	/* Captured length can't exceed the snapshot length */
111	if (caplen > p->snapshot)
112		caplen = p->snapshot;
113
114	if (p->fcode.bf_insns == NULL ||
115	    bpf_filter(p->fcode.bf_insns, bp, cc, caplen)) {
116		struct pcap_pkthdr h;
117
118		++p->md.stat.ps_recv;
119		/* Get timestamp */
120		if (ioctl(p->fd, SIOCGSTAMP, &h.ts) < 0) {
121			sprintf(p->errbuf, "SIOCGSTAMP: %s",
122			    pcap_strerror(errno));
123			return (-1);
124		}
125		h.len = cc;
126		h.caplen = caplen;
127		(*callback)(user, &h, bp);
128		return (1);
129	}
130	return (0);
131}
132
133pcap_t *
134pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
135{
136	register int fd, broadcast;
137	register pcap_t *p;
138	struct ifreq ifr;
139
140	p = (pcap_t *)malloc(sizeof(*p));
141	if (p == NULL) {
142		sprintf(ebuf, "malloc: %s", pcap_strerror(errno));
143		return (NULL);
144	}
145	memset((char *)p, 0, sizeof(*p));
146	fd = -1;
147
148	/* XXX hack - map device name to link layer type */
149	broadcast = 0;
150	if (strncmp("eth", device, 3) == 0) {
151		p->linktype = DLT_EN10MB;
152		++broadcast;
153	} else if (strncmp("sl", device, 2) == 0) {
154		p->linktype = DLT_SLIP;
155		p->md.pad = 16;
156	} else if (strncmp("ppp", device, 3) == 0) {
157		p->linktype = DLT_PPP;
158		p->md.pad = 4;
159	} else if (strncmp("lo", device, 2) == 0) {
160		p->linktype = DLT_NULL;
161		p->md.pad = 2;
162		p->md.skip = 12;
163	} else {
164		sprintf(ebuf, "linux: unknown physical layer type");
165		goto bad;
166	}
167
168	/* Linux is full of magic numbers */
169	fd = socket(PF_INET, SOCK_PACKET, htons(0x0003));
170	if (fd < 0) {
171		sprintf(ebuf, "linux socket: %s", pcap_strerror(errno));
172		goto bad;
173	}
174	p->fd = fd;
175
176
177	p->bufsize = 4096;				/* XXX */
178	p->buffer = (u_char *)malloc(p->bufsize);
179	if (p->buffer == NULL) {
180		sprintf(ebuf, "malloc: %s", pcap_strerror(errno));
181		goto bad;
182	}
183
184	/* XXX */
185	if (promisc && broadcast) {
186		memset(&ifr, 0, sizeof(ifr));
187		strcpy(ifr.ifr_name, device);
188		if (ioctl(p->fd, SIOCGIFFLAGS, &ifr) < 0 ) {
189			sprintf(ebuf, "SIOCGIFFLAGS: %s", pcap_strerror(errno));
190			goto bad;
191		}
192		saved_ifr = ifr;
193		ifr.ifr_flags |= IFF_PROMISC;
194		if (ioctl(p->fd, SIOCSIFFLAGS, &ifr) < 0 ) {
195			sprintf(ebuf, "SIOCSIFFLAGS: %s", pcap_strerror(errno));
196			goto bad;
197		}
198		ifr.ifr_flags &= ~IFF_PROMISC;
199		atexit(linux_restore_ifr);
200	}
201
202	p->md.device = strdup(device);
203	if (p->md.device == NULL) {
204		sprintf(ebuf, "malloc: %s", pcap_strerror(errno));
205		goto bad;
206	}
207	p->snapshot = snaplen;
208
209	return (p);
210bad:
211	if (fd >= 0)
212		(void)close(fd);
213	if (p->buffer != NULL)
214		free(p->buffer);
215	if (p->md.device != NULL)
216		free(p->md.device);
217	free(p);
218	return (NULL);
219}
220
221int
222pcap_setfilter(pcap_t *p, struct bpf_program *fp)
223{
224
225	p->fcode = *fp;
226	return (0);
227}
228
229void
230linux_restore_ifr(void)
231{
232	register int fd;
233
234	fd = socket(PF_INET, SOCK_PACKET, htons(0x0003));
235	if (fd < 0)
236		fprintf(stderr, "linux socket: %s", pcap_strerror(errno));
237	else if (ioctl(fd, SIOCSIFFLAGS, &saved_ifr) < 0)
238		fprintf(stderr, "linux SIOCSIFFLAGS: %s", pcap_strerror(errno));
239}
240