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 1.5 2007/11/25 01:28:23 swildner 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 <string.h>
  39 #include <pcap.h>
  40
  41 #include "common.h"
  42 #include "eloop.h"
  43 #include "l2_packet.h"
  44
  45 static const u8 pae_group_addr[ETH_ALEN] =
  46         { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
  47
  48 struct l2_packet_data {
  49         pcap_t *pcap;
  50         char ifname[100];
  51         u8 own_addr[ETH_ALEN];
  52         void (*rx_callback)(void *ctx, const u8 *src_addr,
  53                             const u8 *buf, size_t len);
  54         void *rx_callback_ctx;
  55         int l2_hdr; /* whether to include layer 2 (Ethernet) header data
  56                      * buffers */
  57 };
  58
  59 int
  60 l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
  61 {
  62         memcpy(addr, l2->own_addr, ETH_ALEN);
  63         return 0;
  64 }
  65
  66 int
  67 l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
  68 {
  69         pcap_if_t *devs, *dev;
  70         struct pcap_addr *addr;
  71         struct sockaddr_in *saddr;
  72         int found = 0;
  73         char err[PCAP_ERRBUF_SIZE + 1];
  74
  75         if (pcap_findalldevs(&devs, err) < 0) {
  76                 wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
  77                 return -1;
  78         }
  79
  80         for (dev = devs; dev && !found; dev = dev->next) {
  81                 if (strcmp(dev->name, l2->ifname) != 0)
  82                         continue;
  83
  84                 addr = dev->addresses;
  85                 while (addr) {
  86                         saddr = (struct sockaddr_in *) addr->addr;
  87                         if (saddr && saddr->sin_family == AF_INET) {
  88                                 snprintf(buf, len, "%s",
  89                                          inet_ntoa(saddr->sin_addr));
  90                                 found = 1;
  91                                 break;
  92                         }
  93                         addr = addr->next;
  94                 }
  95         }
  96
  97         pcap_freealldevs(devs);
  98
  99         return found ? 0 : -1;
 100 }
 101
 102 void
 103 l2_packet_notify_auth_start(struct l2_packet_data *l2)
 104 {
 105 }
 106
 107 int
 108 l2_packet_send(struct l2_packet_data *l2,
 109         const u8 *dst_addr, u16 proto, const u8 *buf, size_t len)
 110 {
 111         if (!l2->l2_hdr) {
 112                 int ret;
 113                 struct l2_ethhdr *eth = malloc(sizeof(*eth) + len);
 114                 if (eth == NULL)
 115                         return -1;
 116                 memcpy(eth->h_dest, dst_addr, ETH_ALEN);
 117                 memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
 118                 eth->h_proto = htons(proto);
 119                 memcpy(eth + 1, buf, len);
 120                 ret = pcap_inject(l2->pcap, (u8 *) eth, len + sizeof(*eth));
 121                 free(eth);
 122                 return ret;
 123         } else
 124                 return pcap_inject(l2->pcap, buf, len);
 125 }
 126
 127
 128 static void
 129 l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
 130 {
 131         struct l2_packet_data *l2 = eloop_ctx;
 132         pcap_t *pcap = sock_ctx;
 133         struct pcap_pkthdr hdr;
 134         const u_char *packet;
 135         struct l2_ethhdr *ethhdr;
 136         unsigned char *buf;
 137         size_t len;
 138
 139         packet = pcap_next(pcap, &hdr);
 140
 141         if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
 142                 return;
 143
 144         ethhdr = (struct l2_ethhdr *) packet;
 145         if (l2->l2_hdr) {
 146                 buf = (unsigned char *) ethhdr;
 147                 len = hdr.caplen;
 148         } else {
 149                 buf = (unsigned char *) (ethhdr + 1);
 150                 len = hdr.caplen - sizeof(*ethhdr);
 151         }
 152         l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
 153 }
 154
 155 static int
 156 l2_packet_init_libpcap(struct l2_packet_data *l2, unsigned short protocol)
 157 {
 158         bpf_u_int32 pcap_maskp, pcap_netp;
 159         char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
 160         struct bpf_program pcap_fp;
 161
 162         pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
 163         l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
 164         if (l2->pcap == NULL) {
 165                 fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
 166                 fprintf(stderr, "ifname='%s'\n", l2->ifname);
 167                 return -1;
 168         }
 169         if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
 170             pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
 171                 fprintf(stderr, "pcap_set_datalink(DLT_EN10MB): %s\n",
 172                         pcap_geterr(l2->pcap));
 173                 return -1;
 174         }
 175         snprintf(pcap_filter, sizeof(pcap_filter),
 176                  "not ether src " MACSTR " and "
 177                  "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
 178                  "ether proto 0x%x",
 179                  MAC2STR(l2->own_addr), /* do not receive own packets */
 180                  MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
 181                  protocol);
 182         if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
 183                 fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
 184                 return -1;
 185         }
 186
 187         if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
 188                 fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
 189                 return -1;
 190         }
 191
 192         pcap_freecode(&pcap_fp);
 193         /*
 194          * When libpcap uses BPF we must enable "immediate mode" to
 195          * receive frames right away; otherwise the system may
 196          * buffer them for us.
 197          */
 198         { unsigned int on = 1;
 199           if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
 200                 fprintf(stderr, "%s: cannot enable immediate mode on "
 201                         "interface %s: %s\n",
 202                         __func__, l2->ifname, strerror(errno));
 203                 /* XXX should we fail? */
 204           }
 205         }
 206
 207         eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
 208                                  l2_packet_receive, l2, l2->pcap);
 209
 210         return 0;
 211 }
 212
 213 static void
 214 l2_packet_deinit_libpcap(struct l2_packet_data *l2)
 215 {
 216         if (l2->pcap != NULL) {
 217                 eloop_unregister_read_sock(pcap_get_selectable_fd(l2->pcap));
 218                 pcap_close(l2->pcap);
 219                 l2->pcap = NULL;
 220         }
 221 }
 222
 223 static int
 224 eth_get(const char *device, u8 ea[ETH_ALEN])
 225 {
 226         struct if_msghdr *ifm;
 227         struct sockaddr_dl *sdl;
 228         u_char *p, *buf;
 229         size_t len;
 230         int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK, NET_RT_IFLIST, 0 };
 231
 232         if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
 233                 return -1;
 234         if ((buf = malloc(len)) == NULL)
 235                 return -1;
 236         if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
 237                 free(buf);
 238                 return -1;
 239         }
 240         for (p = buf; p < buf + len; p += ifm->ifm_msglen) {
 241                 ifm = (struct if_msghdr *)p;
 242                 sdl = (struct sockaddr_dl *)(ifm + 1);
 243                 if (ifm->ifm_type != RTM_IFINFO ||
 244                     (ifm->ifm_addrs & RTA_IFP) == 0)
 245                         continue;
 246                 if (sdl->sdl_family != AF_LINK || sdl->sdl_nlen == 0 ||
 247                     memcmp(sdl->sdl_data, device, sdl->sdl_nlen) != 0)
 248                         continue;
 249                 memcpy(ea, LLADDR(sdl), sdl->sdl_alen);
 250                 break;
 251         }
 252         free(buf);
 253
 254         if (p >= buf + len) {
 255                 errno = ESRCH;
 256                 return -1;
 257         }
 258         return 0;
 259 }
 260
 261 struct l2_packet_data *
 262 l2_packet_init(const char *ifname, const u8 *own_addr, unsigned short protocol,
 263         void (*rx_callback)(void *ctx, const u8 *src_addr,
 264                             const u8 *buf, size_t len),
 265         void *rx_callback_ctx, int l2_hdr)
 266 {
 267         struct l2_packet_data *l2;
 268
 269         l2 = malloc(sizeof(struct l2_packet_data));
 270         if (l2 == NULL)
 271                 return NULL;
 272         memset(l2, 0, sizeof(*l2));
 273         strncpy(l2->ifname, ifname, sizeof(l2->ifname));
 274         l2->rx_callback = rx_callback;
 275         l2->rx_callback_ctx = rx_callback_ctx;
 276         l2->l2_hdr = l2_hdr;
 277
 278         if (eth_get(l2->ifname, l2->own_addr) < 0) {
 279                 fprintf(stderr, "Failed to get link-level address for "
 280                         "interface '%s'.\n", l2->ifname);
 281                 free(l2);
 282                 return NULL;
 283         }
 284
 285         if (l2_packet_init_libpcap(l2, protocol) != 0) {
 286                 free(l2);
 287                 return NULL;
 288         }
 289         return l2;
 290 }
 291
 292 void
 293 l2_packet_deinit(struct l2_packet_data *l2)
 294 {
 295         if (l2 != NULL) {
 296                 l2_packet_deinit_libpcap(l2);
 297                 free(l2);
 298         }
 299 }