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