text: /* $Id$ */
  
  /*
   *   Copyright (c) 2001-2010 Aaron Turner <aturner at synfin dot net>
   *   Copyright (c) 2013-2017 Fred Klassen <tcpreplay at appneta dot com> - AppNeta
   *
   *   The Tcpreplay Suite of tools is free software: you can redistribute it 
   *   and/or modify it under the terms of the GNU General Public License as 
   *   published by the Free Software Foundation, either version 3 of the 
   *   License, or with the authors permission any later version.
   *
   *   The Tcpreplay Suite is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *   GNU General Public License for more details.
   *
   *   You should have received a copy of the GNU General Public License
   *   along with the Tcpreplay Suite.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <stdlib.h>
  #include <string.h>
  
  #include "tcpedit.h"
  #include "common.h"
  #include "tcpr.h"
  #include "dlt_utils.h"
  #include "tcpedit_stub.h"
  #include "ieee80211.h"
  #include "ieee80211_hdr.h"
  
  /*
   * Notes about the ieee80211 plugin:
   * 802.11 is a little different from most other L2 protocols:
   * - Not all frames are data frames (control, data, management) (data frame == L3 or higher included)
   * - Not all data frames have data (QoS frames are "data" frames, but have no L3 header)
   * - L2 header is 802.11 + an 802.2/802.2SNAP header
   */
  static char dlt_name[] = "ieee80211";
  _U_ static char dlt_prefix[] = "ieee802_11";
  static uint16_t dlt_value = DLT_IEEE802_11;
  
  /*
   * Function to register ourselves.  This function is always called, regardless
   * of what DLT types are being used, so it shouldn't be allocating extra buffers
   * or anything like that (use the dlt_ieee80211_init() function below for that).
   * Tasks:
   * - Create a new plugin struct
   * - Fill out the provides/requires bit masks.  Note:  Only specify which fields are
   *   actually in the header.
   * - Add the plugin to the context's plugin chain
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_ieee80211_register(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      assert(ctx);
  
      /* create  a new plugin structure */
      plugin = tcpedit_dlt_newplugin();
  
      /* we're a decoder only plugin */
      plugin->provides += PLUGIN_MASK_PROTO + PLUGIN_MASK_SRCADDR + PLUGIN_MASK_DSTADDR;
      plugin->requires += 0;
      
       /* what is our DLT value? */
      plugin->dlt = dlt_value;
  
      /* set the prefix name of our plugin.  This is also used as the prefix for our options */
      plugin->name = safe_strdup(dlt_name);
  
      /* 
       * Point to our functions, note, you need a function for EVERY method.  
       * Even if it is only an empty stub returning success.
       */
      plugin->plugin_init = dlt_ieee80211_init;
      plugin->plugin_cleanup = dlt_ieee80211_cleanup;
      plugin->plugin_parse_opts = dlt_ieee80211_parse_opts;
      plugin->plugin_decode = dlt_ieee80211_decode;
      plugin->plugin_encode = dlt_ieee80211_encode;
      plugin->plugin_proto = dlt_ieee80211_proto;
      plugin->plugin_l2addr_type = dlt_ieee80211_l2addr_type;
      plugin->plugin_l2len = dlt_ieee80211_l2len;
      plugin->plugin_get_layer3 = dlt_ieee80211_get_layer3;
      plugin->plugin_merge_layer3 = dlt_ieee80211_merge_layer3;
      plugin->plugin_get_mac = dlt_ieee80211_get_mac;
  
      /* add it to the available plugin list */
      return tcpedit_dlt_addplugin(ctx, plugin);
  }
  
   
  /*
   * Initializer function.  This function is called only once, if and only iif
   * this plugin will be utilized.  Remember, if you need to keep track of any state, 
   * store it in your plugin->config, not a global!
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_ieee80211_init(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      assert(ctx);
      
      if ((plugin = tcpedit_dlt_getplugin(ctx, dlt_value)) == NULL) {
          tcpedit_seterr(ctx->tcpedit, "Unable to initialize unregistered plugin %s", dlt_name);
          return TCPEDIT_ERROR;
      }
      
      /* allocate memory for our deocde extra data */
      if (sizeof(ieee80211_extra_t) > 0)
          ctx->decoded_extra = safe_malloc(sizeof(ieee80211_extra_t));
  
      /* allocate memory for our config data */
      if (sizeof(ieee80211_config_t) > 0)
          plugin->config = safe_malloc(sizeof(ieee80211_config_t));
  
      /* FIXME: set default config values here */
  
      return TCPEDIT_OK; /* success */
  }
  
  /*
   * Since this is used in a library, we should manually clean up after ourselves
   * Unless you allocated some memory in dlt_ieee80211_init(), this is just an stub.
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_ieee80211_cleanup(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      assert(ctx);
  
      if ((plugin = tcpedit_dlt_getplugin(ctx, dlt_value)) == NULL) {
          tcpedit_seterr(ctx->tcpedit, "Unable to cleanup unregistered plugin %s", dlt_name);
          return TCPEDIT_ERROR;
      }
  
      if (ctx->decoded_extra != NULL) {
          safe_free(ctx->decoded_extra);
          ctx->decoded_extra = NULL;
      }
          
      if (plugin->config != NULL) {
          safe_free(plugin->config);
          plugin->config = NULL;
      }
  
      return TCPEDIT_OK; /* success */
  }
  
  /*
   * This is where you should define all your AutoGen AutoOpts option parsing.
   * Any user specified option should have it's bit turned on in the 'provides'
   * bit mask.
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_ieee80211_parse_opts(tcpeditdlt_t *ctx)
  {
      assert(ctx);
  
      /* we have none */
      
      return TCPEDIT_OK; /* success */
  }
  
  /*
   * Function to decode the layer 2 header in the packet.
   * You need to fill out:
   * - ctx->l2len
   * - ctx->srcaddr
   * - ctx->dstaddr
   * - ctx->proto
   * - ctx->decoded_extra
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_ieee80211_decode(tcpeditdlt_t *ctx, const u_char *packet, const int pktlen)
  {
      int l2len;
  
      assert(ctx);
      assert(packet);
  
      l2len = dlt_ieee80211_l2len(ctx, packet, pktlen);
  
      if (pktlen < l2len)
          return TCPEDIT_ERROR;
  
      dbgx(3, "Decoding 802.11 packet " COUNTER_SPEC, ctx->tcpedit->runtime.packetnum);
      if (! ieee80211_is_data(ctx, packet, pktlen)) {
          tcpedit_seterr(ctx->tcpedit, "Packet " COUNTER_SPEC " is not a normal 802.11 data frame",
              ctx->tcpedit->runtime.packetnum);
          return TCPEDIT_SOFT_ERROR;
      }
      
      if (ieee80211_is_encrypted(ctx, packet, pktlen)) {
          tcpedit_seterr(ctx->tcpedit, "Packet " COUNTER_SPEC " is encrypted.  Unable to decode frame.",
              ctx->tcpedit->runtime.packetnum);
          return TCPEDIT_SOFT_ERROR;
      }
  
      ctx->l2len = l2len;
      memcpy(&(ctx->srcaddr), ieee80211_get_src((ieee80211_hdr_t *)packet), ETHER_ADDR_LEN);
      memcpy(&(ctx->dstaddr), ieee80211_get_dst((ieee80211_hdr_t *)packet), ETHER_ADDR_LEN);
      ctx->proto = dlt_ieee80211_proto(ctx, packet, pktlen);
  
      return TCPEDIT_OK; /* success */
  }
  
  /*
   * Function to encode the layer 2 header back into the packet.
   * Returns: total packet len or TCPEDIT_ERROR
   */
  int 
  dlt_ieee80211_encode(tcpeditdlt_t *ctx, u_char *packet, int pktlen, _U_ tcpr_dir_t dir)
  {
      assert(ctx);
      assert(packet);
      
      tcpedit_seterr(ctx->tcpedit, "%s", "DLT_IEEE802_11 plugin does not support packet encoding");
      return TCPEDIT_ERROR;
  }
  
  /*
   * Function returns the Layer 3 protocol type of the given packet, or TCPEDIT_ERROR on error
   */
  int 
  dlt_ieee80211_proto(tcpeditdlt_t *ctx, const u_char *packet, const int pktlen)
  {
      int l2len;
      int hdrlen = 0;
      uint16_t *frame_control, fc;
      struct tcpr_802_2snap_hdr *hdr;
  
      assert(ctx);
      assert(packet);
  
      l2len = dlt_ieee80211_l2len(ctx, packet, pktlen);
      if (pktlen < l2len)
          return TCPEDIT_ERROR;
  
      /* check 802.11 frame control field */
      frame_control = (uint16_t *)packet;
      fc = ntohs(*frame_control);
  
      /* Not all 802.11 frames have data */
      if ((fc & ieee80211_FC_TYPE_MASK) != ieee80211_FC_TYPE_DATA)
          return TCPEDIT_SOFT_ERROR;
      
      /* Some data frames are QoS and have no data 
          if (((fc & ieee80211_FC_SUBTYPE_MASK) & ieee80211_FC_SUBTYPE_QOS) == ieee80211_FC_SUBTYPE_QOS)
          return TCPEDIT_SOFT_ERROR;
      */
      if ((fc & ieee80211_FC_SUBTYPE_QOS) == ieee80211_FC_SUBTYPE_QOS) {
          hdrlen += 2;
      }
      
      /* figure out the actual header length */
      if (ieee80211_USE_4(fc)) {
          hdrlen += sizeof(ieee80211_addr4_hdr_t);
      } else {
          hdrlen += sizeof(ieee80211_hdr_t);
      }
      
      hdr = (struct tcpr_802_2snap_hdr *)&packet[hdrlen];
  
      /* verify the header is 802.2SNAP (8 bytes) not 802.2 (3 bytes) */
      if (hdr->snap_dsap == 0xAA && hdr->snap_ssap == 0xAA)
          return hdr->snap_type;
      
  
      return TCPEDIT_SOFT_ERROR; /* 802.2 has no type field */
  }
  
  /*
   * Function returns a pointer to the layer 3 protocol header or NULL on error
   */
  u_char *
  dlt_ieee80211_get_layer3(tcpeditdlt_t *ctx, u_char *packet, const int pktlen)
  {
      int l2len;
      assert(ctx);
      assert(packet);
  
      l2len = dlt_ieee80211_l2len(ctx, packet, pktlen);
  
      if (pktlen < l2len)
          return NULL;
  
      dbgx(1, "Getting data for packet " COUNTER_SPEC " from offset: %d", ctx->tcpedit->runtime.packetnum, l2len);
  
      return tcpedit_dlt_l3data_copy(ctx, packet, pktlen, l2len);
  }
  
  /*
   * function merges the packet (containing L2 and old L3) with the l3data buffer
   * containing the new l3 data.  Note, if L2 % 4 == 0, then they're pointing to the
   * same buffer, otherwise there was a memcpy involved on strictly aligned architectures
   * like SPARC
   */
  u_char *
  dlt_ieee80211_merge_layer3(tcpeditdlt_t *ctx, u_char *packet, const int pktlen, u_char *l3data)
  {
      int l2len;
      assert(ctx);
      assert(packet);
      assert(l3data);
  
      l2len = dlt_ieee80211_l2len(ctx, packet, pktlen);
      
      if (pktlen < l2len)
          return NULL;
      
      return tcpedit_dlt_l3data_merge(ctx, packet, pktlen, l3data, l2len);
  }
  
  /* 
   * return the length of the L2 header of the current packet
   * based on: http://www.tcpdump.org/lists/workers/2004/07/msg00121.html
   */
  int
  dlt_ieee80211_l2len(tcpeditdlt_t *ctx, const u_char *packet, const int pktlen)
  {
      uint16_t *frame_control, fc;
      struct tcpr_802_2snap_hdr *hdr;
      int hdrlen = 0;
  
  
      assert(ctx);
      assert(packet);
  
      if (pktlen < (int)sizeof(uint16_t))
          return 0;
  
      dbgx(2, "packet = %p\t\tplen = %d", packet, pktlen);
  
      frame_control = (uint16_t *)packet;
      fc = ntohs(*frame_control);
  
      if (ieee80211_USE_4(fc)) {
          hdrlen = sizeof(ieee80211_addr4_hdr_t);
      } else {
          hdrlen = sizeof(ieee80211_hdr_t);
      }
      
      /* if Data/QoS, then L2 len is + 2 bytes */
      if ((fc & ieee80211_FC_SUBTYPE_QOS) == ieee80211_FC_SUBTYPE_QOS) {
          dbgx(2, "total header length (fc %04x) (802.11 + QoS data): %d", fc, hdrlen + 2);
          hdrlen += 2;
      }
  
      if (pktlen >= (hdrlen + (int)sizeof(struct tcpr_802_2snap_hdr))) {
      
          hdr = (struct tcpr_802_2snap_hdr *)&packet[hdrlen];
      
          /* verify the header is 802.2SNAP (8 bytes) not 802.2 (3 bytes) */
          if (hdr->snap_dsap == 0xAA && hdr->snap_ssap == 0xAA) {
              hdrlen += (int)sizeof(struct tcpr_802_2snap_hdr);
              dbgx(2, "total header length (802.11 + 802.2SNAP): %d", hdrlen);
          } else {
              hdrlen += (int)sizeof(struct tcpr_802_2_hdr);
              dbgx(2, "total header length (802.11 + 802.2): %d (%02x/%02x)", hdrlen, hdr->snap_dsap, hdr->snap_ssap);
          }
      }
  
      if (pktlen < hdrlen)
          return 0;
      
      dbgx(2, "header length: %d", hdrlen);
      return hdrlen;
  }
  
  /*
   * return a static pointer to the source/destination MAC address
   * return NULL on error/address doesn't exist
   */    
  u_char *
  dlt_ieee80211_get_mac(tcpeditdlt_t *ctx, tcpeditdlt_mac_type_t mac, const u_char *packet, const int pktlen)
  {
      assert(ctx);
      assert(packet);
      u_char *macaddr;
  
      if (pktlen < 14)
          return NULL;
      
      switch(mac) {
      case SRC_MAC:
          macaddr = ieee80211_get_src(packet);
          memcpy(ctx->srcmac, macaddr, ETHER_ADDR_LEN);
          return(ctx->srcmac);
          break;
          
      case DST_MAC:
          macaddr = ieee80211_get_dst(packet);
          memcpy(ctx->dstmac, macaddr, ETHER_ADDR_LEN);
          return(ctx->dstmac);
          break;
          
      default:
          errx(1, "Invalid tcpeditdlt_mac_type_t: %d", mac);
      }
      return(NULL);
  }
  
  
  tcpeditdlt_l2addr_type_t 
  dlt_ieee80211_l2addr_type(void)
  {
      return ETHERNET;
  }
  
  