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 "../ethernet.h"
  #include "en10mb.h"
  
  
  static char _U_ dlt_name[] = "en10mb";
  static char dlt_prefix[] = "enet";
  static uint16_t dlt_value = DLT_EN10MB;
  
  /*
   * 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_en10mb_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_en10mb_register(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      assert(ctx);
  
      /* create  a new plugin structure */
      plugin = tcpedit_dlt_newplugin();
  
      /* set what we provide & require */
      plugin->provides += PLUGIN_MASK_PROTO + PLUGIN_MASK_SRCADDR + PLUGIN_MASK_DSTADDR;
      plugin->requires += PLUGIN_MASK_PROTO + PLUGIN_MASK_SRCADDR + PLUGIN_MASK_DSTADDR;
  
      /* what is our dlt type? */
      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_prefix);
  
      /* 
       * 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_en10mb_init;
      plugin->plugin_cleanup = dlt_en10mb_cleanup;
      plugin->plugin_parse_opts = dlt_en10mb_parse_opts;
      plugin->plugin_decode = dlt_en10mb_decode;
      plugin->plugin_encode = dlt_en10mb_encode;
      plugin->plugin_proto = dlt_en10mb_proto;
      plugin->plugin_l2addr_type = dlt_en10mb_l2addr_type;
      plugin->plugin_l2len = dlt_en10mb_l2len;
      plugin->plugin_get_layer3 = dlt_en10mb_get_layer3;
      plugin->plugin_merge_layer3 = dlt_en10mb_merge_layer3;
      plugin->plugin_get_mac = dlt_en10mb_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_en10mb_init(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      en10mb_config_t *config;
      assert(ctx);
      
      /* vlan tags need an additional 4 bytes */
      if ((plugin = tcpedit_dlt_getplugin(ctx, dlt_value)) == NULL) {
          tcpedit_seterr(ctx->tcpedit, "%s", "Unable to initialize unregistered plugin en10mb");
          return TCPEDIT_ERROR;
      }
      
      ctx->decoded_extra = safe_malloc(sizeof(en10mb_extra_t));
      plugin->config = safe_malloc(sizeof(en10mb_config_t));
      config = (en10mb_config_t *)plugin->config;
      
      /* init vlan user values to -1 to indicate not set */
      config->vlan_tag = 65535;
      config->vlan_pri = 255;
      config->vlan_cfi = 255;
      
      
      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_en10mb_init(), this is just an stub.
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_en10mb_cleanup(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      
      assert(ctx);
      
      if ((plugin = tcpedit_dlt_getplugin(ctx, dlt_value)) == NULL)
          return TCPEDIT_OK;
  
      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 */
  }
  
  int
  dlt_en10mb_parse_subsmac_entry(const char *raw, en10mb_sub_entry_t *entry)
  {
      char  *candidate = safe_strdup(raw);
      int parse_result = dualmac2hex(candidate, entry->target, entry->rewrite, SUBSMAC_ENTRY_LEN);
  
      free(candidate);
  
      return parse_result;
  }
  
  en10mb_sub_entry_t *
  dlt_en10mb_realloc_merge(en10mb_sub_conf_t config, en10mb_sub_entry_t *new_entries, int entries_count)
  {
      int i;
      en10mb_sub_entry_t *merged = safe_realloc(
          config.entries, (config.count + entries_count) * sizeof(en10mb_sub_entry_t));
  
      for (i = 0; i < entries_count; i++) {
          merged[config.count + i] = new_entries[i];
      }
  
      return merged;
  }
  
  int
  dlt_en10mb_parse_subsmac(tcpeditdlt_t *ctx, en10mb_config_t *config, const char *input)
  {
      int input_len = strlen(input);
  
      int possible_entries_number = (input_len / (SUBSMAC_ENTRY_LEN + 1)) + 1;
      int entry = 0;
  
      en10mb_sub_entry_t *entries = safe_malloc(possible_entries_number * sizeof(en10mb_sub_entry_t));
  
      for (entry = 0; entry < possible_entries_number; entry++) {
          const int read_offset = entry + entry * SUBSMAC_ENTRY_LEN;
  
          if (input_len - read_offset < SUBSMAC_ENTRY_LEN) {
              free(entries);
              tcpedit_seterr(ctx->tcpedit, "Unable to parse --enet-subsmac=%s", input);
              return TCPEDIT_ERROR;
          }
  
          switch(dlt_en10mb_parse_subsmac_entry(input + read_offset, &entries[entry])) {
              case 3:
                  /* Both read; This is what we want */
                  break;
              default:
                  free(entries);
                  tcpedit_seterr(ctx->tcpedit, "Unable to parse --enet-subsmac=%s", input);
                  return TCPEDIT_ERROR;
          }
      }
  
      config->subs.entries = dlt_en10mb_realloc_merge(config->subs, entries, possible_entries_number);
      config->subs.count  += possible_entries_number;
  
      free(entries);
  
      return TCPEDIT_OK;
  }
  
  /*
   * 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_en10mb_parse_opts(tcpeditdlt_t *ctx)
  {
      tcpeditdlt_plugin_t *plugin;
      en10mb_config_t *config;
      assert(ctx);
  
      plugin = tcpedit_dlt_getplugin(ctx, dlt_value);
      config = (en10mb_config_t *)plugin->config;
  
      /* --subsmacs */
      if (HAVE_OPT(ENET_SUBSMAC)) {
          int i, count = STACKCT_OPT(ENET_SUBSMAC);
          char **list  = (char**) STACKLST_OPT(ENET_SUBSMAC);
          for (i = 0; i < count; i++) {
              int parse_result = dlt_en10mb_parse_subsmac(ctx, config, list[i]);
              if (parse_result == TCPEDIT_ERROR) {
                  return TCPEDIT_ERROR;
              }
          }
      }
  
      /* --mac-seed */
      if (HAVE_OPT(ENET_MAC_SEED)) {
          int i,j;
  
          config->random.set = OPT_VALUE_ENET_MAC_SEED;
  
          for (i = 0; i < 6; i++) {
            config->random.mask[i] = (u_char)tcpr_random(&config->random.set) % 256;
            /* only unique numbers */
            for (j = 0; j < i; j++) {
              if (config->random.mask[i] == config->random.mask[j]) {
                i--;
                break;
              }
            }
          }
  
          if (HAVE_OPT(ENET_MAC_SEED_KEEP_BYTES)) {
            config->random.keep = OPT_VALUE_ENET_MAC_SEED_KEEP_BYTES;
          }
      }
  
      /* --dmac */
      if (HAVE_OPT(ENET_DMAC)) {
          int macparse;
          macparse = dualmac2hex(OPT_ARG(ENET_DMAC), config->intf1_dmac,
                      config->intf2_dmac, strlen(OPT_ARG(ENET_DMAC)));
          switch (macparse) {
              case 1:
                  config->mac_mask += TCPEDIT_MAC_MASK_DMAC1;
                  break;
              case 2:
                  config->mac_mask += TCPEDIT_MAC_MASK_DMAC2;
                  break;
              case 3:
                  config->mac_mask += TCPEDIT_MAC_MASK_DMAC1;
                  config->mac_mask += TCPEDIT_MAC_MASK_DMAC2;
                  break;
              case 0:
                  /* nothing to do */
                  break;
              default:
                  tcpedit_seterr(ctx->tcpedit, 
                          "Unable to parse --enet-dmac=%s", OPT_ARG(ENET_DMAC));
                  return TCPEDIT_ERROR;
                  break;
          }
  
          plugin->requires -= PLUGIN_MASK_DSTADDR;
  
      }
  
      /* --smac */
      if (HAVE_OPT(ENET_SMAC)) {
          int macparse;
          macparse = dualmac2hex(OPT_ARG(ENET_SMAC), config->intf1_smac,
                      config->intf2_smac, strlen(OPT_ARG(ENET_SMAC)));
          switch (macparse) {
              case 1:
                  config->mac_mask += TCPEDIT_MAC_MASK_SMAC1;
                  break;
              case 2:
                  config->mac_mask += TCPEDIT_MAC_MASK_SMAC2;
                  break;
              case 3:
                  config->mac_mask += TCPEDIT_MAC_MASK_SMAC1;
                  config->mac_mask += TCPEDIT_MAC_MASK_SMAC2;
                  break;
              case 0:
                  /* nothing to do */
                  break;
              default:
                  tcpedit_seterr(ctx->tcpedit,
                          "Unable to parse --enet-smac=%s", OPT_ARG(ENET_SMAC));
                  return TCPEDIT_ERROR;
                  break;
          }
          plugin->requires -= PLUGIN_MASK_SRCADDR;
      }
  
      /*
       * Validate 802.1q vlan args and populate tcpedit->vlan_record
       */
      if (HAVE_OPT(ENET_VLAN)) {
          if (strcmp(OPT_ARG(ENET_VLAN), "add") == 0) { // add or change
              config->vlan = TCPEDIT_VLAN_ADD;
          } else if (strcmp(OPT_ARG(ENET_VLAN), "del") == 0) {
              config->vlan = TCPEDIT_VLAN_DEL;
          } else {
              tcpedit_seterr(ctx->tcpedit, "Invalid --enet-vlan=%s", OPT_ARG(ENET_VLAN));
              return -1;
          }
  
          if (config->vlan != TCPEDIT_VLAN_OFF) {
              if (config->vlan == TCPEDIT_VLAN_ADD) {
                  if (! HAVE_OPT(ENET_VLAN_TAG)) {
                      tcpedit_seterr(ctx->tcpedit, "%s",
                              "Must specify a new 802.1 VLAN tag if vlan "
                              "mode is add");
                      return TCPEDIT_ERROR;
                  }
  
                  /*
                   * fill out the 802.1q header
                   */
                  config->vlan_tag = OPT_VALUE_ENET_VLAN_TAG;
  
                  dbgx(1, "We will %s 802.1q headers", 
                      config->vlan == TCPEDIT_VLAN_DEL ? "delete" : "add/modify");
  
              if (HAVE_OPT(ENET_VLAN_PRI))
                  config->vlan_pri = OPT_VALUE_ENET_VLAN_PRI;
  
              if (HAVE_OPT(ENET_VLAN_CFI))
                  config->vlan_cfi = OPT_VALUE_ENET_VLAN_CFI;
              }
          }
      }
  
  
      return TCPEDIT_OK; /* success */
  }
  
  /*
   * Function to decode the layer 2 header in the packet
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_en10mb_decode(tcpeditdlt_t *ctx, const u_char *packet, const int pktlen)
  {
      struct tcpr_ethernet_hdr *eth = NULL;
      struct tcpr_802_1q_hdr *vlan = NULL;
      en10mb_extra_t *extra = NULL;
      
      assert(ctx);
      assert(packet);
      if (pktlen < 14)
          return TCPEDIT_ERROR;
  
      /* get our src & dst address */
      eth = (struct tcpr_ethernet_hdr *)packet;
      memcpy(&(ctx->dstaddr.ethernet), eth, ETHER_ADDR_LEN);
      memcpy(&(ctx->srcaddr.ethernet), &(eth->ether_shost), ETHER_ADDR_LEN);
  
      extra = (en10mb_extra_t *)ctx->decoded_extra;
      extra->vlan = 0;
      
      /* get the L3 protocol type  & L2 len*/
      switch (ntohs(eth->ether_type)) {
          case ETHERTYPE_VLAN:
              vlan = (struct tcpr_802_1q_hdr *)packet;
              ctx->proto = vlan->vlan_len;
              
              /* Get VLAN tag info */
              extra->vlan = 1;
              /* must use these mask values, rather then what's in the tcpr.h since it assumes you're shifting */
              extra->vlan_tag = vlan->vlan_priority_c_vid & 0x0FFF;
              extra->vlan_pri = vlan->vlan_priority_c_vid & 0xE000;
              extra->vlan_cfi = vlan->vlan_priority_c_vid & 0x1000;
              ctx->l2len = TCPR_802_1Q_H;
              break;
          
          /* we don't properly handle SNAP encoding */
          default:
              ctx->proto = eth->ether_type;
              ctx->l2len = TCPR_802_3_H;
              break;
      }
  
      return TCPEDIT_OK; /* success */
  }
  
  /*
   * Function to encode the layer 2 header back into the packet.
   * Returns: TCPEDIT_ERROR | TCPEDIT_OK | TCPEDIT_WARN
   */
  int 
  dlt_en10mb_encode(tcpeditdlt_t *ctx, u_char *packet, int pktlen, tcpr_dir_t dir)
  {
      tcpeditdlt_plugin_t *plugin = NULL;
      struct tcpr_ethernet_hdr *eth = NULL;
      struct tcpr_802_1q_hdr *vlan = NULL;
      en10mb_config_t *config = NULL;
      en10mb_extra_t *extra = NULL;
      
      int newl2len = 0;
  
      assert(ctx);
      assert(packet);
  
      if (pktlen < 14) {
          tcpedit_seterr(ctx->tcpedit, 
                  "Unable to process packet #" COUNTER_SPEC " since it is less then 14 bytes.", 
                  ctx->tcpedit->runtime.packetnum);
          return TCPEDIT_ERROR;
      }
  
      plugin = tcpedit_dlt_getplugin(ctx, dlt_value);
      config = plugin->config;
      extra = (en10mb_extra_t *)ctx->decoded_extra;
      
      /* figure out the new layer2 length, first for the case: ethernet -> ethernet? */
      if (ctx->decoder->dlt == dlt_value) {
          if ((ctx->l2len == TCPR_802_1Q_H && config->vlan == TCPEDIT_VLAN_OFF) ||
              (config->vlan == TCPEDIT_VLAN_ADD)) {
              newl2len = TCPR_802_1Q_H;
          } else if ((ctx->l2len == TCPR_802_3_H && config->vlan == TCPEDIT_VLAN_OFF) ||
              (config->vlan == TCPEDIT_VLAN_DEL)) {
              newl2len = TCPR_802_3_H;
          }
      } 
      
      /* newl2len for some other DLT -> ethernet */
      else {
          /* if add a vlan then 18, else 14 bytes */
          newl2len = config->vlan == TCPEDIT_VLAN_ADD ? TCPR_802_1Q_H : TCPR_802_3_H;
      }
  
      /* Make space for our new L2 header */
      if (newl2len != ctx->l2len)
          memmove(packet + newl2len, packet + ctx->l2len, pktlen - ctx->l2len);
  
      /* update the total packet length */
      pktlen += newl2len - ctx->l2len;
      
      /* always set the src & dst address as the first 12 bytes */
      eth = (struct tcpr_ethernet_hdr *)packet;
      
      if (dir == TCPR_DIR_C2S) {
          /* copy user supplied SRC MAC if provided or from original packet */
          if (config->mac_mask & TCPEDIT_MAC_MASK_SMAC1) {
              if ((ctx->addr_type == ETHERNET && 
                      ((ctx->skip_broadcast && 
                        is_unicast_ethernet(ctx, ctx->srcaddr.ethernet)) || !ctx->skip_broadcast))
                  || ctx->addr_type != ETHERNET) {
                  memcpy(eth->ether_shost, config->intf1_smac, ETHER_ADDR_LEN);
              } else {
                  memcpy(eth->ether_shost, ctx->srcaddr.ethernet, ETHER_ADDR_LEN);                
              }
          } else if (ctx->addr_type == ETHERNET) {
              memcpy(eth->ether_shost, ctx->srcaddr.ethernet, ETHER_ADDR_LEN);
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Please provide a source address");
              return TCPEDIT_ERROR;
          }
  
          /* copy user supplied DMAC MAC if provided or from original packet */        
          if (config->mac_mask & TCPEDIT_MAC_MASK_DMAC1) {
              if ((ctx->addr_type == ETHERNET && 
                  ((ctx->skip_broadcast && is_unicast_ethernet(ctx, ctx->dstaddr.ethernet)) || !ctx->skip_broadcast))
                  || ctx->addr_type != ETHERNET) {
                  memcpy(eth->ether_dhost, config->intf1_dmac, ETHER_ADDR_LEN);
              } else {
                  memcpy(eth->ether_dhost, ctx->dstaddr.ethernet, ETHER_ADDR_LEN);
              }
          } else if (ctx->addr_type == ETHERNET) {
              memcpy(eth->ether_dhost, ctx->dstaddr.ethernet, ETHER_ADDR_LEN);
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Please provide a destination address");
              return TCPEDIT_ERROR;            
          }
      
      } else if (dir == TCPR_DIR_S2C) {
          /* copy user supplied SRC MAC if provided or from original packet */
          if (config->mac_mask & TCPEDIT_MAC_MASK_SMAC2) {
              if ((ctx->addr_type == ETHERNET && 
                  ((ctx->skip_broadcast && is_unicast_ethernet(ctx, ctx->srcaddr.ethernet)) || !ctx->skip_broadcast))
                  || ctx->addr_type != ETHERNET) {
                  memcpy(eth->ether_shost, config->intf2_smac, ETHER_ADDR_LEN);
              } else {
                  memcpy(eth->ether_shost, ctx->srcaddr.ethernet, ETHER_ADDR_LEN);
              }
          } else if (ctx->addr_type == ETHERNET) {
              memcpy(eth->ether_shost, ctx->srcaddr.ethernet, ETHER_ADDR_LEN);            
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Please provide a source address");
              return TCPEDIT_ERROR;
          }
  
          
          /* copy user supplied DMAC MAC if provided or from original packet */        
          if (config->mac_mask & TCPEDIT_MAC_MASK_DMAC2) {
              if ((ctx->addr_type == ETHERNET && 
                  ((ctx->skip_broadcast && is_unicast_ethernet(ctx, ctx->dstaddr.ethernet)) || !ctx->skip_broadcast))
                  || ctx->addr_type != ETHERNET) {
                  memcpy(eth->ether_dhost, config->intf2_dmac, ETHER_ADDR_LEN);
              } else {
                  memcpy(eth->ether_dhost, ctx->dstaddr.ethernet, ETHER_ADDR_LEN);                
              }
          } else if (ctx->addr_type == ETHERNET) {
              memcpy(eth->ether_dhost, ctx->dstaddr.ethernet, ETHER_ADDR_LEN);
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Please provide a destination address");
              return TCPEDIT_ERROR;
          }
  
          
      } else {
          tcpedit_seterr(ctx->tcpedit, "%s", "Encoders only support C2S or C2S!");
          return TCPEDIT_ERROR;
      }
  
      if (config->subs.entries) {
        int  entry = 0;
        for (entry = 0 ; entry < config->subs.count; entry++) {
          en10mb_sub_entry_t *current = &config->subs.entries[entry];
  
          if (!memcmp(eth->ether_dhost, current->target, ETHER_ADDR_LEN)) {
            memcpy(eth->ether_dhost, current->rewrite, ETHER_ADDR_LEN);
          }
  
          if (!memcmp(eth->ether_shost, current->target, ETHER_ADDR_LEN)) {
            memcpy(eth->ether_shost, current->rewrite, ETHER_ADDR_LEN);
          }
        }
      }
  
      if (config->random.set) {
        int unicast_src = is_unicast_ethernet(ctx, eth->ether_shost);
        int unicast_dst = is_unicast_ethernet(ctx, eth->ether_dhost);
  
        int i = config->random.keep;
        for ( ; i < ETHER_ADDR_LEN; i++) {
          eth->ether_shost[i] = MAC_MASK_APPLY(eth->ether_shost[i], config->random.mask[i], unicast_src);
          eth->ether_dhost[i] = MAC_MASK_APPLY(eth->ether_dhost[i], config->random.mask[i], unicast_dst);
        }
  
        /* avoid making unicast packets multicast */
        if (!config->random.keep) {
          eth->ether_shost[0] &= ~(0x01 * unicast_src);
          eth->ether_dhost[0] &= ~(0x01 * unicast_dst);
        }
      }
  
      if (newl2len == TCPR_802_3_H) {
          /* all we need for 802.3 is the proto */
          eth->ether_type = ctx->proto;
          
      } else if (newl2len == TCPR_802_1Q_H) {
          /* VLAN tags need a bit more */
          vlan = (struct tcpr_802_1q_hdr *)packet;
          vlan->vlan_len = ctx->proto;
          vlan->vlan_tpi = htons(ETHERTYPE_VLAN);
          
          /* are we changing VLAN info? */
          if (config->vlan_tag < 65535) {
              vlan->vlan_priority_c_vid = 
                  htons((uint16_t)config->vlan_tag & TCPR_802_1Q_VIDMASK);
          } else if (extra->vlan) {
              vlan->vlan_priority_c_vid = extra->vlan_tag;
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Non-VLAN tagged packet requires --enet-vlan-tag");
              return TCPEDIT_ERROR;
          }
          
          if (config->vlan_pri < 255) {
              vlan->vlan_priority_c_vid += htons((uint16_t)config->vlan_pri << 13);
          } else if (extra->vlan) {
              vlan->vlan_priority_c_vid += extra->vlan_pri;
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Non-VLAN tagged packet requires --enet-vlan-pri");
              return TCPEDIT_ERROR;
          }
              
          if (config->vlan_cfi < 255) {
              vlan->vlan_priority_c_vid += htons((uint16_t)config->vlan_cfi << 12);
          } else if (extra->vlan) {
              vlan->vlan_priority_c_vid += extra->vlan_cfi;
          } else {
              tcpedit_seterr(ctx->tcpedit, "%s", "Non-VLAN tagged packet requires --enet-vlan-cfi");
              return TCPEDIT_ERROR;            
          }        
          
      } else {
          tcpedit_seterr(ctx->tcpedit, "Unsupported new layer 2 length: %d", newl2len);
          return TCPEDIT_ERROR;
      }
  
      return pktlen;
  }
  
  
  /*
   * Function returns the Layer 3 protocol type of the given packet, or TCPEDIT_ERROR on error
   */
  int 
  dlt_en10mb_proto(tcpeditdlt_t *ctx, const u_char *packet, const int pktlen)
  {
      struct tcpr_ethernet_hdr *eth = NULL;
      struct tcpr_802_1q_hdr *vlan = NULL;
      
      assert(ctx);
      assert(packet);
      if (pktlen < (int) sizeof(*eth))
          return TCPEDIT_ERROR;
      
      eth = (struct tcpr_ethernet_hdr *)packet;
      switch (ntohs(eth->ether_type)) {
          case ETHERTYPE_VLAN:
              vlan = (struct tcpr_802_1q_hdr *)packet;
              return vlan->vlan_len;
              break;
          
          default:
              return eth->ether_type;
              break;
      }
      return TCPEDIT_ERROR;
  }
  
  /*
   * Function returns a pointer to the layer 3 protocol header or NULL on error
   */
  u_char *
  dlt_en10mb_get_layer3(tcpeditdlt_t *ctx, u_char *packet, const int pktlen)
  {
      int l2len;
      assert(ctx);
      assert(packet);
      
      l2len = dlt_en10mb_l2len(ctx, packet, pktlen);
  
      if (pktlen < l2len)
          return NULL;
  
      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_en10mb_merge_layer3(tcpeditdlt_t *ctx, u_char *packet, const int pktlen, u_char *l3data)
  {
      int l2len;
      assert(ctx);
      assert(packet);
      assert(l3data);
      
      l2len = dlt_en10mb_l2len(ctx, packet, pktlen);
      
      if (pktlen < l2len)
          return NULL;
      
      return tcpedit_dlt_l3data_merge(ctx, packet, pktlen, l3data, l2len);
  }
  
  /*
   * return a static pointer to the source/destination MAC address
   * return NULL on error/address doesn't exist
   */    
  u_char *
  dlt_en10mb_get_mac(tcpeditdlt_t *ctx, tcpeditdlt_mac_type_t mac, const u_char *packet, const int pktlen)
  {
      assert(ctx);
      assert(packet);
      if (pktlen < 14)
          return NULL;
  
      /* FIXME: return a ptr to the source or dest mac address. */
      switch(mac) {
      case SRC_MAC:
          memcpy(ctx->srcmac, &packet[6], ETHER_ADDR_LEN);
          return(ctx->srcmac);
          break;
          
      case DST_MAC:
          memcpy(ctx->dstmac, packet, ETHER_ADDR_LEN);
          return(ctx->dstmac);
          break;
          
      default:
          errx(1, "Invalid tcpeditdlt_mac_type_t: %d", mac);
      }
      return(NULL);
  }
  
  /* 
   * return the length of the L2 header of the current packet
   */
  int
  dlt_en10mb_l2len(tcpeditdlt_t *ctx, const u_char *packet, const int pktlen)
  {
      int l2len;
      struct tcpr_ethernet_hdr *eth = NULL;
      
      assert(ctx);
      assert(packet);
  
      eth = (struct tcpr_ethernet_hdr *)packet;
      switch (ntohs(eth->ether_type)) {
          case ETHERTYPE_VLAN:
              l2len = 18;
              break;
          
          default:
              l2len = 14;
              break;
      }
  
      if (l2len > 0) {
          if (pktlen < l2len) {
              /* can happen if fuzzing is enabled */
              return 0;
          }
  
          return l2len;
      }
  
      tcpedit_seterr(ctx->tcpedit, "%s", "Whoops!  Bug in my code!");
      return -1;
  }
  
  tcpeditdlt_l2addr_type_t
  dlt_en10mb_l2addr_type(void)
  {
      return ETHERNET;
  }
  