usr.sbin/802_11/l2_packet.c

   1 /*
   2  * WPA Supplicant - Layer2 packet handling
   3  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
   4  * Copyright (c) 2005, Sam Leffler <sam@errno.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Alternatively, this software may be distributed under the terms of BSD
  11  * license.
  12  *
  13  * See README and COPYING for more details.
  14  *
  15  * $FreeBSD: src/usr.sbin/wpa/l2_packet.c,v 1.4 2007/07/09 15:57:10 sam Exp $
  16  * $DragonFly: src/usr.sbin/802_11/l2_packet.c,v 1.4 2007/08/07 11:25:36 sephe Exp $
  17  */
  18
  19 /*
  20  * DragonFlyBSD-specific implementation.
  21  */
  22 #include <sys/types.h>
  23 #include <sys/ioctl.h>
  24 #include <sys/socket.h>
  25 #include <sys/sysctl.h>
  26
  27 #include <net/if.h>
  28 #include <net/if_dl.h>
  29 #include <net/bpf.h>
  30 #include <net/route.h>
  31 #include <netinet/in.h>
  32 #include <arpa/inet.h>
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <stdlib.h>
  37 #include <stdio.h>
  38 #include <pcap.h>
  39
  40 #include "common.h"
  41 #include "eloop.h"
  42 #include "l2_packet.h"
  43
  44 static const u8 pae_group_addr[ETH_ALEN] =
  45         { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
  46
  47 struct l2_packet_data {
  48         pcap_t *pcap;
  49         char ifname[100];
  50         u8 own_addr[ETH_ALEN];
  51         void (*rx_callback)(void *ctx, const u8 *src_addr,
  52                             const u8 *buf, size_t len);
  53         void *rx_callback_ctx;
  54         int l2_hdr; /* whether to include layer 2 (Ethernet) header data
  55                      * buffers */
  56 };
  57
  58 int
  59 l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
  60 {
  61         memcpy(addr, l2->own_addr, ETH_ALEN);
  62         return 0;
  63 }
  64
  65 int
  66 l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
  67 {
  68         pcap_if_t *devs, *dev;
  69         struct pcap_addr *addr;
  70         struct sockaddr_in *saddr;
  71         int found = 0;
  72         char err[PCAP_ERRBUF_SIZE + 1];
  73
  74         if (pcap_findalldevs(&devs, err) < 0) {
  75                 wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
  76                 return -1;
  77         }
  78
  79         for (dev = devs; dev && !found; dev = dev->next) {
  80                 if (strcmp(dev->name, l2->ifname) != 0)
  81                         continue;
  82
  83                 addr = dev->addresses;
  84                 while (addr) {
  85                         saddr = (struct sockaddr_in *) addr->addr;
  86                         if (saddr && saddr->sin_family == AF_INET) {
  87                                 snprintf(buf, len, "%s",
  88                                          inet_ntoa(saddr->sin_addr));
  89                                 found = 1;
  90                                 break;
  91                         }
  92                         addr = addr->next;
  93                 }
  94         }
  95
  96         pcap_freealldevs(devs);
  97
  98         return found ? 0 : -1;
  99 }
 100
 101 void
 102 l2_packet_notify_auth_start(struct l2_packet_data *l2)
 103 {
 104 }
 105
 106 int
 107 l2_packet_send(struct l2_packet_data *l2,
 108         const u8 *dst_addr, u16 proto, const u8 *buf, size_t len)
 109 {
 110         if (!l2->l2_hdr) {
 111                 int ret;
 112                 struct l2_ethhdr *eth = malloc(sizeof(*eth) + len);
 113                 if (eth == NULL)
 114                         return -1;
 115                 memcpy(eth->h_dest, dst_addr, ETH_ALEN);
 116                 memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
 117                 eth->h_proto = htons(proto);
 118                 memcpy(eth + 1, buf, len);
 119                 ret = pcap_inject(l2->pcap, (u8 *) eth, len + sizeof(*eth));
 120                 free(eth);
 121                 return ret;
 122         } else
 123                 return pcap_inject(l2->pcap, buf, len);
 124 }
 125
 126
 127 static void
 128 l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
 129 {
 130         struct l2_packet_data *l2 = eloop_ctx;
 131         pcap_t *pcap = sock_ctx;
 132         struct pcap_pkthdr hdr;
 133         const u_char *packet;
 134         struct l2_ethhdr *ethhdr;
 135         unsigned char *buf;
 136         size_t len;
 137
 138         packet = pcap_next(pcap, &hdr);
 139
 140         if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
 141                 return;
 142
 143         ethhdr = (struct l2_ethhdr *) packet;
 144         if (l2->l2_hdr) {
 145                 buf = (unsigned char *) ethhdr;
 146                 len = hdr.caplen;
 147         } else {
 148                 buf = (unsigned char *) (ethhdr + 1);
 149                 len = hdr.caplen - sizeof(*ethhdr);
 150         }
 151         l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
 152 }
 153
 154 static int
 155 l2_packet_init_libpcap(struct l2_packet_data *l2, unsigned short protocol)
 156 {
 157         bpf_u_int32 pcap_maskp, pcap_netp;
 158         char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
 159         struct bpf_program pcap_fp;
 160
 161         pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
 162         l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
 163         if (l2->pcap == NULL) {
 164                 fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
 165                 fprintf(stderr, "ifname='%s'\n", l2->ifname);
 166                 return -1;
 167         }
 168         if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
 169             pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
 170                 fprintf(stderr, "pcap_set_datalink(DLT_EN10MB): %s\n",
 171                         pcap_geterr(l2->pcap));
 172                 return -1;
 173         }
 174         snprintf(pcap_filter, sizeof(pcap_filter),
 175                  "not ether src " MACSTR " and "
 176                  "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
 177                  "ether proto 0x%x",
 178                  MAC2STR(l2->own_addr), /* do not receive own packets */
 179                  MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
 180                  protocol);
 181         if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
 182                 fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
 183                 return -1;
 184         }
 185
 186         if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
 187                 fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
 188                 return -1;
 189         }
 190
 191         pcap_freecode(&pcap_fp);
 192         /*
 193          * When libpcap uses BPF we must enable "immediate mode" to
 194          * receive frames right away; otherwise the system may
 195          * buffer them for us.
 196          */
 197         { unsigned int on = 1;
 198           if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
 199                 fprintf(stderr, "%s: cannot enable immediate mode on "
 200                         "interface %s: %s\n",
 201                         __func__, l2->ifname, strerror(errno));
 202                 /* XXX should we fail? */
 203           }
 204         }
 205
 206         eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
 207                                  l2_packet_receive, l2, l2->pcap);
 208
 209         return 0;
 210 }
 211
 212 static void
 213 l2_packet_deinit_libpcap(struct l2_packet_data *l2)
 214 {
 215         if (l2->pcap != NULL) {
 216                 eloop_unregister_read_sock(pcap_get_selectable_fd(l2->pcap));
 217                 pcap_close(l2->pcap);
 218                 l2->pcap = NULL;
 219         }
 220 }
 221
 222 static int
 223 eth_get(const char *device, u8 ea[ETH_ALEN])
 224 {
 225         struct if_msghdr *ifm;
 226         struct sockaddr_dl *sdl;
 227         u_char *p, *buf;
 228         size_t len;
 229         int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK, NET_RT_IFLIST, 0 };
 230
 231         if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
 232                 return -1;
 233         if ((buf = malloc(len)) == NULL)
 234                 return -1;
 235         if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
 236                 free(buf);
 237                 return -1;
 238         }
 239         for (p = buf; p < buf + len; p += ifm->ifm_msglen) {
 240                 ifm = (struct if_msghdr *)p;
 241                 sdl = (struct sockaddr_dl *)(ifm + 1);
 242                 if (ifm->ifm_type != RTM_IFINFO ||
 243                     (ifm->ifm_addrs & RTA_IFP) == 0)
 244                         continue;
 245                 if (sdl->sdl_family != AF_LINK || sdl->sdl_nlen == 0 ||
 246                     memcmp(sdl->sdl_data, device, sdl->sdl_nlen) != 0)
 247                         continue;
 248                 memcpy(ea, LLADDR(sdl), sdl->sdl_alen);
 249                 break;
 250         }
 251         free(buf);
 252
 253         if (p >= buf + len) {
 254                 errno = ESRCH;
 255                 return -1;
 256         }
 257         return 0;
 258 }
 259
 260 struct l2_packet_data *
 261 l2_packet_init(const char *ifname, const u8 *own_addr, unsigned short protocol,
 262         void (*rx_callback)(void *ctx, const u8 *src_addr,
 263                             const u8 *buf, size_t len),
 264         void *rx_callback_ctx, int l2_hdr)
 265 {
 266         struct l2_packet_data *l2;
 267
 268         l2 = malloc(sizeof(struct l2_packet_data));
 269         if (l2 == NULL)
 270                 return NULL;
 271         memset(l2, 0, sizeof(*l2));
 272         strncpy(l2->ifname, ifname, sizeof(l2->ifname));
 273         l2->rx_callback = rx_callback;
 274         l2->rx_callback_ctx = rx_callback_ctx;
 275         l2->l2_hdr = l2_hdr;
 276
 277         if (eth_get(l2->ifname, l2->own_addr) < 0) {
 278                 fprintf(stderr, "Failed to get link-level address for "
 279                         "interface '%s'.\n", l2->ifname);
 280                 free(l2);
 281                 return NULL;
 282         }
 283
 284         if (l2_packet_init_libpcap(l2, protocol) != 0) {
 285                 free(l2);
 286                 return NULL;
 287         }
 288         return l2;
 289 }
 290
 291 void
 292 l2_packet_deinit(struct l2_packet_data *l2)
 293 {
 294         if (l2 != NULL) {
 295                 l2_packet_deinit_libpcap(l2);
 296                 free(l2);
 297         }
 298 }