src/l2_packet/l2_packet_pcap.c

   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
  29 static const u8 pae_group_addr[ETH_ALEN] =
  30 { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
  31
  32 struct 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
  49 int 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
  57 static 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
  83 int 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
 123 static 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
 152 static 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
 180 static 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
 202 static 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
 284 struct 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
 320 void 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
 338 int 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
 374 void 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 }