contrib/hostapd/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 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
  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
  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                 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
  77 int 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
 117 static 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
 146 static 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
 174 static 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
 196 static 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
 278 struct 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
 314 void 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
 332 int 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
 368 void 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 }