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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 
23 static const u8 pae_group_addr[ETH_ALEN] =
24 { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
25 
26 struct 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 
l2_packet_get_own_addr(struct l2_packet_data * l2,u8 * addr)43 int 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
l2_packet_init_libdnet(struct l2_packet_data * l2)51 static 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 		wpa_printf(MSG_ERROR,
58 			   "Failed to open interface '%s' - eth_open: %s",
59 			   l2->ifname, strerror(errno));
60 		return -1;
61 	}
62 
63 	if (eth_get(l2->eth, &own_addr) < 0) {
64 		wpa_printf(MSG_ERROR,
65 			   "Failed to get own hw address from interface '%s' - eth_get: %s",
66 			   l2->ifname, strerror(errno));
67 		eth_close(l2->eth);
68 		l2->eth = NULL;
69 		return -1;
70 	}
71 	os_memcpy(l2->own_addr, own_addr.data, ETH_ALEN);
72 
73 	return 0;
74 }
75 #endif /* CONFIG_WINPCAP */
76 
77 
l2_packet_send(struct l2_packet_data * l2,const u8 * dst_addr,u16 proto,const u8 * buf,size_t len)78 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
79 		   const u8 *buf, size_t len)
80 {
81 	int ret;
82 	struct l2_ethhdr *eth;
83 
84 	if (l2 == NULL)
85 		return -1;
86 
87 	if (l2->l2_hdr) {
88 #ifdef CONFIG_WINPCAP
89 		ret = pcap_sendpacket(l2->pcap, buf, len);
90 #else /* CONFIG_WINPCAP */
91 		ret = eth_send(l2->eth, buf, len);
92 #endif /* CONFIG_WINPCAP */
93 	} else {
94 		size_t mlen = sizeof(*eth) + len;
95 		eth = os_malloc(mlen);
96 		if (eth == NULL)
97 			return -1;
98 
99 		os_memcpy(eth->h_dest, dst_addr, ETH_ALEN);
100 		os_memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
101 		eth->h_proto = htons(proto);
102 		os_memcpy(eth + 1, buf, len);
103 
104 #ifdef CONFIG_WINPCAP
105 		ret = pcap_sendpacket(l2->pcap, (u8 *) eth, mlen);
106 #else /* CONFIG_WINPCAP */
107 		ret = eth_send(l2->eth, (u8 *) eth, mlen);
108 #endif /* CONFIG_WINPCAP */
109 
110 		os_free(eth);
111 	}
112 
113 	return ret;
114 }
115 
116 
117 #ifndef CONFIG_WINPCAP
l2_packet_receive(int sock,void * eloop_ctx,void * sock_ctx)118 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
119 {
120 	struct l2_packet_data *l2 = eloop_ctx;
121 	pcap_t *pcap = sock_ctx;
122 	struct pcap_pkthdr hdr;
123 	const u_char *packet;
124 	struct l2_ethhdr *ethhdr;
125 	unsigned char *buf;
126 	size_t len;
127 
128 	packet = pcap_next(pcap, &hdr);
129 
130 	if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
131 		return;
132 
133 	ethhdr = (struct l2_ethhdr *) packet;
134 	if (l2->l2_hdr) {
135 		buf = (unsigned char *) ethhdr;
136 		len = hdr.caplen;
137 	} else {
138 		buf = (unsigned char *) (ethhdr + 1);
139 		len = hdr.caplen - sizeof(*ethhdr);
140 	}
141 	l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
142 }
143 #endif /* CONFIG_WINPCAP */
144 
145 
146 #ifdef CONFIG_WINPCAP
l2_packet_receive_cb(u_char * user,const struct pcap_pkthdr * hdr,const u_char * pkt_data)147 static void l2_packet_receive_cb(u_char *user, const struct pcap_pkthdr *hdr,
148 				 const u_char *pkt_data)
149 {
150 	struct l2_packet_data *l2 = (struct l2_packet_data *) user;
151 	struct l2_ethhdr *ethhdr;
152 	unsigned char *buf;
153 	size_t len;
154 
155 	if (pkt_data == NULL || hdr->caplen < sizeof(*ethhdr))
156 		return;
157 
158 	ethhdr = (struct l2_ethhdr *) pkt_data;
159 	if (l2->l2_hdr) {
160 		buf = (unsigned char *) ethhdr;
161 		len = hdr->caplen;
162 	} else {
163 		buf = (unsigned char *) (ethhdr + 1);
164 		len = hdr->caplen - sizeof(*ethhdr);
165 	}
166 	l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
167 	/*
168 	 * Use shorter poll interval for 3 seconds to reduce latency during key
169 	 * handshake.
170 	 */
171 	l2->num_fast_poll = 3 * 50;
172 }
173 
174 
l2_packet_receive_timeout(void * eloop_ctx,void * timeout_ctx)175 static void l2_packet_receive_timeout(void *eloop_ctx, void *timeout_ctx)
176 {
177 	struct l2_packet_data *l2 = eloop_ctx;
178 	pcap_t *pcap = timeout_ctx;
179 	int timeout;
180 
181 	if (l2->num_fast_poll > 0) {
182 		timeout = 20000;
183 		l2->num_fast_poll--;
184 	} else
185 		timeout = 100000;
186 
187 	/* Register new timeout before calling l2_packet_receive() since
188 	 * receive handler may free this l2_packet instance (which will
189 	 * cancel this timeout). */
190 	eloop_register_timeout(0, timeout, l2_packet_receive_timeout,
191 			       l2, pcap);
192 	pcap_dispatch(pcap, 10, l2_packet_receive_cb, (u_char *) l2);
193 }
194 #endif /* CONFIG_WINPCAP */
195 
196 
l2_packet_init_libpcap(struct l2_packet_data * l2,unsigned short protocol)197 static int l2_packet_init_libpcap(struct l2_packet_data *l2,
198 				  unsigned short protocol)
199 {
200 	bpf_u_int32 pcap_maskp, pcap_netp;
201 	char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
202 	struct bpf_program pcap_fp;
203 
204 #ifdef CONFIG_WINPCAP
205 	char ifname[128];
206 	os_snprintf(ifname, sizeof(ifname), "\\Device\\NPF_%s", l2->ifname);
207 	pcap_lookupnet(ifname, &pcap_netp, &pcap_maskp, pcap_err);
208 	l2->pcap = pcap_open_live(ifname, 2500, 0, 10, pcap_err);
209 	if (l2->pcap == NULL) {
210 		fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
211 		fprintf(stderr, "ifname='%s'\n", ifname);
212 		return -1;
213 	}
214 	if (pcap_setnonblock(l2->pcap, 1, pcap_err) < 0)
215 		fprintf(stderr, "pcap_setnonblock: %s\n",
216 			pcap_geterr(l2->pcap));
217 #else /* CONFIG_WINPCAP */
218 	pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
219 	l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
220 	if (l2->pcap == NULL) {
221 		fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
222 		fprintf(stderr, "ifname='%s'\n", l2->ifname);
223 		return -1;
224 	}
225 	if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
226 	    pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
227 		fprintf(stderr, "pcap_set_datalink(DLT_EN10MB): %s\n",
228 			pcap_geterr(l2->pcap));
229 		return -1;
230 	}
231 #endif /* CONFIG_WINPCAP */
232 	os_snprintf(pcap_filter, sizeof(pcap_filter),
233 		    "not ether src " MACSTR " and "
234 		    "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
235 		    "ether proto 0x%x",
236 		    MAC2STR(l2->own_addr), /* do not receive own packets */
237 		    MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
238 		    protocol);
239 	if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
240 		fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
241 		return -1;
242 	}
243 
244 	if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
245 		fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
246 		return -1;
247 	}
248 
249 	pcap_freecode(&pcap_fp);
250 #ifdef BIOCIMMEDIATE
251 	/*
252 	 * When libpcap uses BPF we must enable "immediate mode" to
253 	 * receive frames right away; otherwise the system may
254 	 * buffer them for us.
255 	 */
256 	{
257 		unsigned int on = 1;
258 		if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
259 			fprintf(stderr, "%s: cannot enable immediate mode on "
260 				"interface %s: %s\n",
261 				__func__, l2->ifname, strerror(errno));
262 			/* XXX should we fail? */
263 		}
264 	}
265 #endif /* BIOCIMMEDIATE */
266 
267 #ifdef CONFIG_WINPCAP
268 	eloop_register_timeout(0, 100000, l2_packet_receive_timeout,
269 			       l2, l2->pcap);
270 #else /* CONFIG_WINPCAP */
271 	eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
272 				 l2_packet_receive, l2, l2->pcap);
273 #endif /* CONFIG_WINPCAP */
274 
275 	return 0;
276 }
277 
278 
l2_packet_init(const char * ifname,const u8 * own_addr,unsigned short protocol,void (* rx_callback)(void * ctx,const u8 * src_addr,const u8 * buf,size_t len),void * rx_callback_ctx,int l2_hdr)279 struct l2_packet_data * l2_packet_init(
280 	const char *ifname, const u8 *own_addr, unsigned short protocol,
281 	void (*rx_callback)(void *ctx, const u8 *src_addr,
282 			    const u8 *buf, size_t len),
283 	void *rx_callback_ctx, int l2_hdr)
284 {
285 	struct l2_packet_data *l2;
286 
287 	l2 = os_zalloc(sizeof(struct l2_packet_data));
288 	if (l2 == NULL)
289 		return NULL;
290 	os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
291 	l2->rx_callback = rx_callback;
292 	l2->rx_callback_ctx = rx_callback_ctx;
293 	l2->l2_hdr = l2_hdr;
294 
295 #ifdef CONFIG_WINPCAP
296 	if (own_addr)
297 		os_memcpy(l2->own_addr, own_addr, ETH_ALEN);
298 #else /* CONFIG_WINPCAP */
299 	if (l2_packet_init_libdnet(l2))
300 		return NULL;
301 #endif /* CONFIG_WINPCAP */
302 
303 	if (l2_packet_init_libpcap(l2, protocol)) {
304 #ifndef CONFIG_WINPCAP
305 		eth_close(l2->eth);
306 #endif /* CONFIG_WINPCAP */
307 		os_free(l2);
308 		return NULL;
309 	}
310 
311 	return l2;
312 }
313 
314 
l2_packet_init_bridge(const char * br_ifname,const char * ifname,const u8 * own_addr,unsigned short protocol,void (* rx_callback)(void * ctx,const u8 * src_addr,const u8 * buf,size_t len),void * rx_callback_ctx,int l2_hdr)315 struct l2_packet_data * l2_packet_init_bridge(
316 	const char *br_ifname, const char *ifname, const u8 *own_addr,
317 	unsigned short protocol,
318 	void (*rx_callback)(void *ctx, const u8 *src_addr,
319 			    const u8 *buf, size_t len),
320 	void *rx_callback_ctx, int l2_hdr)
321 {
322 	return l2_packet_init(br_ifname, own_addr, protocol, rx_callback,
323 			      rx_callback_ctx, l2_hdr);
324 }
325 
326 
l2_packet_deinit(struct l2_packet_data * l2)327 void l2_packet_deinit(struct l2_packet_data *l2)
328 {
329 	if (l2 == NULL)
330 		return;
331 
332 #ifdef CONFIG_WINPCAP
333 	eloop_cancel_timeout(l2_packet_receive_timeout, l2, l2->pcap);
334 #else /* CONFIG_WINPCAP */
335 	if (l2->eth)
336 		eth_close(l2->eth);
337 	eloop_unregister_read_sock(pcap_get_selectable_fd(l2->pcap));
338 #endif /* CONFIG_WINPCAP */
339 	if (l2->pcap)
340 		pcap_close(l2->pcap);
341 	os_free(l2);
342 }
343 
344 
l2_packet_get_ip_addr(struct l2_packet_data * l2,char * buf,size_t len)345 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
346 {
347 	pcap_if_t *devs, *dev;
348 	struct pcap_addr *addr;
349 	struct sockaddr_in *saddr;
350 	int found = 0;
351 	char err[PCAP_ERRBUF_SIZE + 1];
352 
353 	if (pcap_findalldevs(&devs, err) < 0) {
354 		wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
355 		return -1;
356 	}
357 
358 	for (dev = devs; dev && !found; dev = dev->next) {
359 		if (os_strcmp(dev->name, l2->ifname) != 0)
360 			continue;
361 
362 		addr = dev->addresses;
363 		while (addr) {
364 			saddr = (struct sockaddr_in *) addr->addr;
365 			if (saddr && saddr->sin_family == AF_INET) {
366 				os_strlcpy(buf, inet_ntoa(saddr->sin_addr),
367 					   len);
368 				found = 1;
369 				break;
370 			}
371 			addr = addr->next;
372 		}
373 	}
374 
375 	pcap_freealldevs(devs);
376 
377 	return found ? 0 : -1;
378 }
379 
380 
l2_packet_notify_auth_start(struct l2_packet_data * l2)381 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
382 {
383 #ifdef CONFIG_WINPCAP
384 	/*
385 	 * Use shorter poll interval for 3 seconds to reduce latency during key
386 	 * handshake.
387 	 */
388 	l2->num_fast_poll = 3 * 50;
389 	eloop_cancel_timeout(l2_packet_receive_timeout, l2, l2->pcap);
390 	eloop_register_timeout(0, 10000, l2_packet_receive_timeout,
391 			       l2, l2->pcap);
392 #endif /* CONFIG_WINPCAP */
393 }
394 
395 
l2_packet_set_packet_filter(struct l2_packet_data * l2,enum l2_packet_filter_type type)396 int l2_packet_set_packet_filter(struct l2_packet_data *l2,
397 				enum l2_packet_filter_type type)
398 {
399 	return -1;
400 }
401