l2_packet_pcap.c revision 8d520ff1dc2da35cdca849e982051b86468016d8 
1/*
2 * WPA Supplicant - Layer2 packet handling with libpcap/libdnet and WinPcap
3 * Copyright (c) 2003-2006, Jouni Malinen <j@w1.fi>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15#include "includes.h"
16#ifndef CONFIG_NATIVE_WINDOWS
17#include <sys/ioctl.h>
18#endif /* CONFIG_NATIVE_WINDOWS */
19#include <pcap.h>
20#ifndef CONFIG_WINPCAP
21#include <dnet.h>
22#endif /* CONFIG_WINPCAP */
23
24#include "common.h"
25#include "eloop.h"
26#include "l2_packet.h"
27
28
29static const u8 pae_group_addr[ETH_ALEN] =
30{ 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
31
32struct l2_packet_data {
33	pcap_t *pcap;
34#ifdef CONFIG_WINPCAP
35	unsigned int num_fast_poll;
36#else /* CONFIG_WINPCAP */
37	eth_t *eth;
38#endif /* CONFIG_WINPCAP */
39	char ifname[100];
40	u8 own_addr[ETH_ALEN];
41	void (*rx_callback)(void *ctx, const u8 *src_addr,
42			    const u8 *buf, size_t len);
43	void *rx_callback_ctx;
44	int l2_hdr; /* whether to include layer 2 (Ethernet) header in calls
45			* to rx_callback */
46};
47
48
49int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
50{
51	os_memcpy(addr, l2->own_addr, ETH_ALEN);
52	return 0;
53}
54
55
56#ifndef CONFIG_WINPCAP
57static int l2_packet_init_libdnet(struct l2_packet_data *l2)
58{
59	eth_addr_t own_addr;
60
61	l2->eth = eth_open(l2->ifname);
62	if (!l2->eth) {
63		printf("Failed to open interface '%s'.\n", l2->ifname);
64		perror("eth_open");
65		return -1;
66	}
67
68	if (eth_get(l2->eth, &own_addr) < 0) {
69		printf("Failed to get own hw address from interface '%s'.\n",
70		       l2->ifname);
71		perror("eth_get");
72		eth_close(l2->eth);
73		l2->eth = NULL;
74		return -1;
75	}
76	os_memcpy(l2->own_addr, own_addr.data, ETH_ALEN);
77
78	return 0;
79}
80#endif /* CONFIG_WINPCAP */
81
82
83int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
84		   const u8 *buf, size_t len)
85{
86	int ret;
87	struct l2_ethhdr *eth;
88
89	if (l2 == NULL)
90		return -1;
91
92	if (l2->l2_hdr) {
93#ifdef CONFIG_WINPCAP
94		ret = pcap_sendpacket(l2->pcap, buf, len);
95#else /* CONFIG_WINPCAP */
96		ret = eth_send(l2->eth, buf, len);
97#endif /* CONFIG_WINPCAP */
98	} else {
99		size_t mlen = sizeof(*eth) + len;
100		eth = os_malloc(mlen);
101		if (eth == NULL)
102			return -1;
103
104		os_memcpy(eth->h_dest, dst_addr, ETH_ALEN);
105		os_memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
106		eth->h_proto = htons(proto);
107		os_memcpy(eth + 1, buf, len);
108
109#ifdef CONFIG_WINPCAP
110		ret = pcap_sendpacket(l2->pcap, (u8 *) eth, mlen);
111#else /* CONFIG_WINPCAP */
112		ret = eth_send(l2->eth, (u8 *) eth, mlen);
113#endif /* CONFIG_WINPCAP */
114
115		os_free(eth);
116	}
117
118	return ret;
119}
120
121
122#ifndef CONFIG_WINPCAP
123static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
124{
125	struct l2_packet_data *l2 = eloop_ctx;
126	pcap_t *pcap = sock_ctx;
127	struct pcap_pkthdr hdr;
128	const u_char *packet;
129	struct l2_ethhdr *ethhdr;
130	unsigned char *buf;
131	size_t len;
132
133	packet = pcap_next(pcap, &hdr);
134
135	if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
136		return;
137
138	ethhdr = (struct l2_ethhdr *) packet;
139	if (l2->l2_hdr) {
140		buf = (unsigned char *) ethhdr;
141		len = hdr.caplen;
142	} else {
143		buf = (unsigned char *) (ethhdr + 1);
144		len = hdr.caplen - sizeof(*ethhdr);
145	}
146	l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
147}
148#endif /* CONFIG_WINPCAP */
149
150
151#ifdef CONFIG_WINPCAP
152static void l2_packet_receive_cb(u_char *user, const struct pcap_pkthdr *hdr,
153				 const u_char *pkt_data)
154{
155	struct l2_packet_data *l2 = (struct l2_packet_data *) user;
156	struct l2_ethhdr *ethhdr;
157	unsigned char *buf;
158	size_t len;
159
160	if (pkt_data == NULL || hdr->caplen < sizeof(*ethhdr))
161		return;
162
163	ethhdr = (struct l2_ethhdr *) pkt_data;
164	if (l2->l2_hdr) {
165		buf = (unsigned char *) ethhdr;
166		len = hdr->caplen;
167	} else {
168		buf = (unsigned char *) (ethhdr + 1);
169		len = hdr->caplen - sizeof(*ethhdr);
170	}
171	l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
172	/*
173	 * Use shorter poll interval for 3 seconds to reduce latency during key
174	 * handshake.
175	 */
176	l2->num_fast_poll = 3 * 50;
177}
178
179
180static void l2_packet_receive_timeout(void *eloop_ctx, void *timeout_ctx)
181{
182	struct l2_packet_data *l2 = eloop_ctx;
183	pcap_t *pcap = timeout_ctx;
184	int timeout;
185
186	if (l2->num_fast_poll > 0) {
187		timeout = 20000;
188		l2->num_fast_poll--;
189	} else
190		timeout = 100000;
191
192	/* Register new timeout before calling l2_packet_receive() since
193	 * receive handler may free this l2_packet instance (which will
194	 * cancel this timeout). */
195	eloop_register_timeout(0, timeout, l2_packet_receive_timeout,
196			       l2, pcap);
197	pcap_dispatch(pcap, 10, l2_packet_receive_cb, (u_char *) l2);
198}
199#endif /* CONFIG_WINPCAP */
200
201
202static int l2_packet_init_libpcap(struct l2_packet_data *l2,
203				  unsigned short protocol)
204{
205	bpf_u_int32 pcap_maskp, pcap_netp;
206	char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
207	struct bpf_program pcap_fp;
208
209#ifdef CONFIG_WINPCAP
210	char ifname[128];
211	os_snprintf(ifname, sizeof(ifname), "\\Device\\NPF_%s", l2->ifname);
212	pcap_lookupnet(ifname, &pcap_netp, &pcap_maskp, pcap_err);
213	l2->pcap = pcap_open_live(ifname, 2500, 0, 10, pcap_err);
214	if (l2->pcap == NULL) {
215		fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
216		fprintf(stderr, "ifname='%s'\n", ifname);
217		return -1;
218	}
219	if (pcap_setnonblock(l2->pcap, 1, pcap_err) < 0)
220		fprintf(stderr, "pcap_setnonblock: %s\n",
221			pcap_geterr(l2->pcap));
222#else /* CONFIG_WINPCAP */
223	pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
224	l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
225	if (l2->pcap == NULL) {
226		fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
227		fprintf(stderr, "ifname='%s'\n", l2->ifname);
228		return -1;
229	}
230	if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
231	    pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
232		fprintf(stderr, "pcap_set_datalink(DLT_EN10MB): %s\n",
233			pcap_geterr(l2->pcap));
234		return -1;
235	}
236#endif /* CONFIG_WINPCAP */
237	os_snprintf(pcap_filter, sizeof(pcap_filter),
238		    "not ether src " MACSTR " and "
239		    "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
240		    "ether proto 0x%x",
241		    MAC2STR(l2->own_addr), /* do not receive own packets */
242		    MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
243		    protocol);
244	if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
245		fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
246		return -1;
247	}
248
249	if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
250		fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
251		return -1;
252	}
253
254	pcap_freecode(&pcap_fp);
255#ifdef BIOCIMMEDIATE
256	/*
257	 * When libpcap uses BPF we must enable "immediate mode" to
258	 * receive frames right away; otherwise the system may
259	 * buffer them for us.
260	 */
261	{
262		unsigned int on = 1;
263		if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
264			fprintf(stderr, "%s: cannot enable immediate mode on "
265				"interface %s: %s\n",
266				__func__, l2->ifname, strerror(errno));
267			/* XXX should we fail? */
268		}
269	}
270#endif /* BIOCIMMEDIATE */
271
272#ifdef CONFIG_WINPCAP
273	eloop_register_timeout(0, 100000, l2_packet_receive_timeout,
274			       l2, l2->pcap);
275#else /* CONFIG_WINPCAP */
276	eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
277				 l2_packet_receive, l2, l2->pcap);
278#endif /* CONFIG_WINPCAP */
279
280	return 0;
281}
282
283
284struct l2_packet_data * l2_packet_init(
285	const char *ifname, const u8 *own_addr, unsigned short protocol,
286	void (*rx_callback)(void *ctx, const u8 *src_addr,
287			    const u8 *buf, size_t len),
288	void *rx_callback_ctx, int l2_hdr)
289{
290	struct l2_packet_data *l2;
291
292	l2 = os_zalloc(sizeof(struct l2_packet_data));
293	if (l2 == NULL)
294		return NULL;
295	os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
296	l2->rx_callback = rx_callback;
297	l2->rx_callback_ctx = rx_callback_ctx;
298	l2->l2_hdr = l2_hdr;
299
300#ifdef CONFIG_WINPCAP
301	if (own_addr)
302		os_memcpy(l2->own_addr, own_addr, ETH_ALEN);
303#else /* CONFIG_WINPCAP */
304	if (l2_packet_init_libdnet(l2))
305		return NULL;
306#endif /* CONFIG_WINPCAP */
307
308	if (l2_packet_init_libpcap(l2, protocol)) {
309#ifndef CONFIG_WINPCAP
310		eth_close(l2->eth);
311#endif /* CONFIG_WINPCAP */
312		os_free(l2);
313		return NULL;
314	}
315
316	return l2;
317}
318
319
320void l2_packet_deinit(struct l2_packet_data *l2)
321{
322	if (l2 == NULL)
323		return;
324
325#ifdef CONFIG_WINPCAP
326	eloop_cancel_timeout(l2_packet_receive_timeout, l2, l2->pcap);
327#else /* CONFIG_WINPCAP */
328	if (l2->eth)
329		eth_close(l2->eth);
330	eloop_unregister_read_sock(pcap_get_selectable_fd(l2->pcap));
331#endif /* CONFIG_WINPCAP */
332	if (l2->pcap)
333		pcap_close(l2->pcap);
334	os_free(l2);
335}
336
337
338int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
339{
340	pcap_if_t *devs, *dev;
341	struct pcap_addr *addr;
342	struct sockaddr_in *saddr;
343	int found = 0;
344	char err[PCAP_ERRBUF_SIZE + 1];
345
346	if (pcap_findalldevs(&devs, err) < 0) {
347		wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
348		return -1;
349	}
350
351	for (dev = devs; dev && !found; dev = dev->next) {
352		if (os_strcmp(dev->name, l2->ifname) != 0)
353			continue;
354
355		addr = dev->addresses;
356		while (addr) {
357			saddr = (struct sockaddr_in *) addr->addr;
358			if (saddr && saddr->sin_family == AF_INET) {
359				os_strlcpy(buf, inet_ntoa(saddr->sin_addr),
360					   len);
361				found = 1;
362				break;
363			}
364			addr = addr->next;
365		}
366	}
367
368	pcap_freealldevs(devs);
369
370	return found ? 0 : -1;
371}
372
373
374void l2_packet_notify_auth_start(struct l2_packet_data *l2)
375{
376#ifdef CONFIG_WINPCAP
377	/*
378	 * Use shorter poll interval for 3 seconds to reduce latency during key
379	 * handshake.
380	 */
381	l2->num_fast_poll = 3 * 50;
382	eloop_cancel_timeout(l2_packet_receive_timeout, l2, l2->pcap);
383	eloop_register_timeout(0, 10000, l2_packet_receive_timeout,
384			       l2, l2->pcap);
385#endif /* CONFIG_WINPCAP */
386}
387