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: head/usr.sbin/wpa/l2_packet.c 172682 2007-10-16 02:12:06Z mlaier $
  16  */
  17
  18 /*
  19  * DragonFly-specific implementation.
  20  */
  21 #include <sys/types.h>
  22 #include <sys/ioctl.h>
  23 #include <sys/socket.h>
  24 #include <sys/sysctl.h>
  25
  26 #include <net/bpf.h>
  27 #include <net/if.h>
  28 #include <net/if_dl.h>
  29 #include <net/route.h>
  30 #include <netinet/in.h>
  31 #include <arpa/inet.h>
  32
  33 #include <stdlib.h>
  34 #include <stdio.h>
  35 #include <string.h>
  36 #include <errno.h>
  37 #include <pcap.h>
  38
  39 #include "common.h"
  40 #include "eloop.h"
  41 #include "l2_packet.h"
  42
  43 static const u8 pae_group_addr[ETH_ALEN] =
  44         { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
  45
  46 struct l2_packet_data {
  47         pcap_t *pcap;
  48         char ifname[100];
  49         u8 own_addr[ETH_ALEN];
  50         void (*rx_callback)(void *ctx, const u8 *src_addr,
  51                             const u8 *buf, size_t len);
  52         void *rx_callback_ctx;
  53         int l2_hdr; /* whether to include layer 2 (Ethernet) header data
  54                      * buffers */
  55 };
  56
  57 int
  58 l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
  59 {
  60         memcpy(addr, l2->own_addr, ETH_ALEN);
  61         return 0;
  62 }
  63
  64 int
  65 l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
  66 {
  67         pcap_if_t *devs, *dev;
  68         struct pcap_addr *addr;
  69         struct sockaddr_in *saddr;
  70         int found = 0;
  71         char err[PCAP_ERRBUF_SIZE + 1];
  72
  73         if (pcap_findalldevs(&devs, err) < 0) {
  74                 wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
  75                 return -1;
  76         }
  77
  78         for (dev = devs; dev && !found; dev = dev->next) {
  79                 if (strcmp(dev->name, l2->ifname) != 0)
  80                         continue;
  81
  82                 addr = dev->addresses;
  83                 while (addr) {
  84                         saddr = (struct sockaddr_in *) addr->addr;
  85                         if (saddr && saddr->sin_family == AF_INET) {
  86                                 snprintf(buf, len, "%s",
  87                                          inet_ntoa(saddr->sin_addr));
  88                                 found = 1;
  89                                 break;
  90                         }
  91                         addr = addr->next;
  92                 }
  93         }
  94
  95         pcap_freealldevs(devs);
  96
  97         return found ? 0 : -1;
  98 }
  99
 100 void
 101 l2_packet_notify_auth_start(struct l2_packet_data *l2)
 102 {
 103 }
 104
 105 int
 106 l2_packet_send(struct l2_packet_data *l2,
 107         const u8 *dst_addr, u16 proto, const u8 *buf, size_t len)
 108 {
 109         if (!l2->l2_hdr) {
 110                 int ret;
 111                 struct l2_ethhdr *eth = malloc(sizeof(*eth) + len);
 112                 if (eth == NULL)
 113                         return -1;
 114                 memcpy(eth->h_dest, dst_addr, ETH_ALEN);
 115                 memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
 116                 eth->h_proto = htons(proto);
 117                 memcpy(eth + 1, buf, len);
 118                 ret = pcap_inject(l2->pcap, (u8 *) eth, len + sizeof(*eth));
 119                 free(eth);
 120                 return ret;
 121         } else
 122                 return pcap_inject(l2->pcap, buf, len);
 123 }
 124
 125
 126 static void
 127 l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
 128 {
 129         struct l2_packet_data *l2 = eloop_ctx;
 130         pcap_t *pcap = sock_ctx;
 131         struct pcap_pkthdr hdr;
 132         const u_char *packet;
 133         struct l2_ethhdr *ethhdr;
 134         unsigned char *buf;
 135         size_t len;
 136
 137         packet = pcap_next(pcap, &hdr);
 138
 139         if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
 140                 return;
 141
 142         ethhdr = (struct l2_ethhdr *) packet;
 143         if (l2->l2_hdr) {
 144                 buf = (unsigned char *) ethhdr;
 145                 len = hdr.caplen;
 146         } else {
 147                 buf = (unsigned char *) (ethhdr + 1);
 148                 len = hdr.caplen - sizeof(*ethhdr);
 149         }
 150         l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
 151 }
 152
 153 static int
 154 l2_packet_init_libpcap(struct l2_packet_data *l2, unsigned short protocol)
 155 {
 156         bpf_u_int32 pcap_maskp, pcap_netp;
 157         char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
 158         struct bpf_program pcap_fp;
 159
 160         pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
 161         l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
 162         if (l2->pcap == NULL) {
 163                 fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
 164                 fprintf(stderr, "ifname='%s'\n", l2->ifname);
 165                 return -1;
 166         }
 167         if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
 168             pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
 169                 fprintf(stderr, "pcap_set_datalink(DLT_EN10MB): %s\n",
 170                         pcap_geterr(l2->pcap));
 171                 return -1;
 172         }
 173         snprintf(pcap_filter, sizeof(pcap_filter),
 174                  "not ether src " MACSTR " and "
 175                  "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
 176                  "ether proto 0x%x",
 177                  MAC2STR(l2->own_addr), /* do not receive own packets */
 178                  MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
 179                  protocol);
 180         if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
 181                 fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
 182                 return -1;
 183         }
 184
 185         if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
 186                 fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
 187                 return -1;
 188         }
 189
 190         pcap_freecode(&pcap_fp);
 191         /*
 192          * When libpcap uses BPF we must enable "immediate mode" to
 193          * receive frames right away; otherwise the system may
 194          * buffer them for us.
 195          */
 196         { unsigned int on = 1;
 197           if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
 198                 fprintf(stderr, "%s: cannot enable immediate mode on "
 199                         "interface %s: %s\n",
 200                         __func__, l2->ifname, strerror(errno));
 201                 /* XXX should we fail? */
 202           }
 203         }
 204
 205         eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
 206                                  l2_packet_receive, l2, l2->pcap);
 207
 208         return 0;
 209 }
 210
 211 static void
 212 l2_packet_deinit_libpcap(struct l2_packet_data *l2)
 213 {
 214         if (l2->pcap != NULL) {
 215                 eloop_unregister_read_sock(pcap_get_selectable_fd(l2->pcap));
 216                 pcap_close(l2->pcap);
 217                 l2->pcap = NULL;
 218         }
 219 }
 220
 221 static int
 222 eth_get(const char *device, u8 ea[ETH_ALEN])
 223 {
 224         struct if_msghdr *ifm;
 225         struct sockaddr_dl *sdl;
 226         u_char *p, *buf;
 227         size_t len;
 228         int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK, NET_RT_IFLIST, 0 };
 229
 230         if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
 231                 return -1;
 232         if ((buf = malloc(len)) == NULL)
 233                 return -1;
 234         if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
 235                 free(buf);
 236                 return -1;
 237         }
 238         for (p = buf; p < buf + len; p += ifm->ifm_msglen) {
 239                 ifm = (struct if_msghdr *)p;
 240                 sdl = (struct sockaddr_dl *)(ifm + 1);
 241                 if (ifm->ifm_type != RTM_IFINFO ||
 242                     (ifm->ifm_addrs & RTA_IFP) == 0)
 243                         continue;
 244                 if (sdl->sdl_family != AF_LINK || sdl->sdl_nlen == 0 ||
 245                     memcmp(sdl->sdl_data, device, sdl->sdl_nlen) != 0)
 246                         continue;
 247                 memcpy(ea, LLADDR(sdl), sdl->sdl_alen);
 248                 break;
 249         }
 250         free(buf);
 251
 252         if (p >= buf + len) {
 253                 errno = ESRCH;
 254                 return -1;
 255         }
 256         return 0;
 257 }
 258
 259 struct l2_packet_data *
 260 l2_packet_init(const char *ifname, const u8 *own_addr, unsigned short protocol,
 261         void (*rx_callback)(void *ctx, const u8 *src_addr,
 262                             const u8 *buf, size_t len),
 263         void *rx_callback_ctx, int l2_hdr)
 264 {
 265         struct l2_packet_data *l2;
 266
 267         l2 = malloc(sizeof(struct l2_packet_data));
 268         if (l2 == NULL)
 269                 return NULL;
 270         memset(l2, 0, sizeof(*l2));
 271         strncpy(l2->ifname, ifname, sizeof(l2->ifname));
 272         l2->rx_callback = rx_callback;
 273         l2->rx_callback_ctx = rx_callback_ctx;
 274         l2->l2_hdr = l2_hdr;
 275
 276         if (eth_get(l2->ifname, l2->own_addr) < 0) {
 277                 fprintf(stderr, "Failed to get link-level address for "
 278                         "interface '%s'.\n", l2->ifname);
 279                 free(l2);
 280                 return NULL;
 281         }
 282
 283         if (l2_packet_init_libpcap(l2, protocol) != 0) {
 284                 free(l2);
 285                 return NULL;
 286         }
 287         return l2;
 288 }
 289
 290 void
 291 l2_packet_deinit(struct l2_packet_data *l2)
 292 {
 293         if (l2 != NULL) {
 294                 l2_packet_deinit_libpcap(l2);
 295                 free(l2);
 296         }
 297 }