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pcap-dag.c

/*
 * pcap-dag.c: Packet capture interface for Endace DAG card.
 *
 * The functionality of this code attempts to mimic that of pcap-linux as much
 * as possible.  This code is compiled in several different ways depending on
 * whether DAG_ONLY and HAVE_DAG_API are defined.  If HAVE_DAG_API is not
 * defined it should not get compiled in, otherwise if DAG_ONLY is defined then
 * the 'dag_' function calls are renamed to 'pcap_' equivalents.  If DAG_ONLY
 * is not defined then nothing is altered - the dag_ functions will be
 * called as required from their pcap-linux/bpf equivalents.
 *
 * Authors: Richard Littin, Sean Irvine ({richard,sean}@reeltwo.com)
 * Modifications: Jesper Peterson  <support@endace.com>
 *                Koryn Grant      <support@endace.com>
 *                Stephen Donnelly <support@endace.com>
 */

#ifndef lint
static const char rcsid[] _U_ =
      "@(#) $Header: /tcpdump/master/libpcap/pcap-dag.c,v 1.31.2.8 2008-04-14 20:41:51 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/param.h>              /* optionally get BSD define */

#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "pcap-int.h"

#include <ctype.h>
#include <netinet/in.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

struct mbuf;            /* Squelch compiler warnings on some platforms for */
struct rtentry;         /* declarations in <net/if.h> */
#include <net/if.h>

#include "dagnew.h"
#include "dagapi.h"

#include "pcap-dag.h"

#define ATM_CELL_SIZE         52
#define ATM_HDR_SIZE          4

/*
 * A header containing additional MTP information.
 */
#define MTP2_SENT_OFFSET            0     /* 1 byte */
#define MTP2_ANNEX_A_USED_OFFSET    1     /* 1 byte */
#define MTP2_LINK_NUMBER_OFFSET           2     /* 2 bytes */
#define MTP2_HDR_LEN                4     /* length of the header */

#define MTP2_ANNEX_A_NOT_USED      0
#define MTP2_ANNEX_A_USED          1
#define MTP2_ANNEX_A_USED_UNKNOWN  2

/* SunATM pseudo header */
struct sunatm_hdr {
      unsigned char     flags;            /* destination and traffic type */
      unsigned char     vpi;        /* VPI */
      unsigned short    vci;        /* VCI */
};

typedef struct pcap_dag_node {
      struct pcap_dag_node *next;
      pcap_t *p;
      pid_t pid;
} pcap_dag_node_t;

static pcap_dag_node_t *pcap_dags = NULL;
static int atexit_handler_installed = 0;
static const unsigned short endian_test_word = 0x0100;

#define IS_BIGENDIAN() (*((unsigned char *)&endian_test_word))


#ifdef DAG_ONLY
/* This code is required when compiling for a DAG device only. */

/* Replace dag function names with pcap equivalent. */
#define dag_create pcap_create
#define dag_platform_finddevs pcap_platform_finddevs
#endif /* DAG_ONLY */

#define MAX_DAG_PACKET 65536

static unsigned char TempPkt[MAX_DAG_PACKET];

static int dag_setfilter(pcap_t *p, struct bpf_program *fp);
static int dag_stats(pcap_t *p, struct pcap_stat *ps);
static int dag_set_datalink(pcap_t *p, int dlt);
static int dag_get_datalink(pcap_t *p);
static int dag_setnonblock(pcap_t *p, int nonblock, char *errbuf);

static void
delete_pcap_dag(pcap_t *p)
{
      pcap_dag_node_t *curr = NULL, *prev = NULL;

      for (prev = NULL, curr = pcap_dags; curr != NULL && curr->p != p; prev = curr, curr = curr->next) {
            /* empty */
      }

      if (curr != NULL && curr->p == p) {
            if (prev != NULL) {
                  prev->next = curr->next;
            } else {
                  pcap_dags = curr->next;
            }
      }
}

/*
 * Performs a graceful shutdown of the DAG card, frees dynamic memory held
 * in the pcap_t structure, and closes the file descriptor for the DAG card.
 */

static void
dag_platform_cleanup(pcap_t *p)
{
      
      if (p != NULL) {
#ifdef HAVE_DAG_STREAMS_API
            if(dag_stop_stream(p->fd, p->md.dag_stream) < 0)
                  fprintf(stderr,"dag_stop_stream: %s\n", strerror(errno));
            
            if(dag_detach_stream(p->fd, p->md.dag_stream) < 0)
                  fprintf(stderr,"dag_detach_stream: %s\n", strerror(errno));
#else
            if(dag_stop(p->fd) < 0)
                  fprintf(stderr,"dag_stop: %s\n", strerror(errno));
#endif /* HAVE_DAG_STREAMS_API */
            if(p->fd != -1) {
                  if(dag_close(p->fd) < 0)
                        fprintf(stderr,"dag_close: %s\n", strerror(errno));
                  p->fd = -1;
            }
            delete_pcap_dag(p);
            pcap_cleanup_live_common(p);
      }
      /* Note: don't need to call close(p->fd) here as dag_close(p->fd) does this. */
}

static void
atexit_handler(void)
{
      while (pcap_dags != NULL) {
            if (pcap_dags->pid == getpid()) {
                  dag_platform_cleanup(pcap_dags->p);
            } else {
                  delete_pcap_dag(pcap_dags->p);
            }
      }
}

static int
new_pcap_dag(pcap_t *p)
{
      pcap_dag_node_t *node = NULL;

      if ((node = malloc(sizeof(pcap_dag_node_t))) == NULL) {
            return -1;
      }

      if (!atexit_handler_installed) {
            atexit(atexit_handler);
            atexit_handler_installed = 1;
      }

      node->next = pcap_dags;
      node->p = p;
      node->pid = getpid();

      pcap_dags = node;

      return 0;
}

static unsigned int
dag_erf_ext_header_count(uint8_t * erf, size_t len)
{
      uint32_t hdr_num = 0;
      uint8_t  hdr_type;

      /* basic sanity checks */
      if ( erf == NULL )
            return 0;
      if ( len < 16 )
            return 0;

      /* check if we have any extension headers */
      if ( (erf[8] & 0x80) == 0x00 )
            return 0;

      /* loop over the extension headers */
      do {
      
            /* sanity check we have enough bytes */
            if ( len <= (24 + (hdr_num * 8)) )
                  return hdr_num;

            /* get the header type */
            hdr_type = erf[(16 + (hdr_num * 8))];
            hdr_num++;

      } while ( hdr_type & 0x80 );

      return hdr_num;
}

/*
 *  Read at most max_packets from the capture stream and call the callback
 *  for each of them. Returns the number of packets handled, -1 if an
 *  error occured, or -2 if we were told to break out of the loop.
 */
static int
dag_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
      unsigned int processed = 0;
      int flags = p->md.dag_offset_flags;
      unsigned int nonblocking = flags & DAGF_NONBLOCK;
      unsigned int num_ext_hdr = 0;

      /* Get the next bufferful of packets (if necessary). */
      while (p->md.dag_mem_top - p->md.dag_mem_bottom < dag_record_size) {
 
            /*
             * Has "pcap_breakloop()" been called?
             */
            if (p->break_loop) {
                  /*
                   * Yes - clear the flag that indicates that
                   * it has, and return -2 to indicate that
                   * we were told to break out of the loop.
                   */
                  p->break_loop = 0;
                  return -2;
            }

#ifdef HAVE_DAG_STREAMS_API
            /* dag_advance_stream() will block (unless nonblock is called)
             * until 64kB of data has accumulated.
             * If to_ms is set, it will timeout before 64kB has accumulated.
             * We wait for 64kB because processing a few packets at a time
             * can cause problems at high packet rates (>200kpps) due
             * to inefficiencies.
             * This does mean if to_ms is not specified the capture may 'hang'
             * for long periods if the data rate is extremely slow (<64kB/sec)
             * If non-block is specified it will return immediately. The user
             * is then responsible for efficiency.
             */
            if ( NULL == (p->md.dag_mem_top = dag_advance_stream(p->fd, p->md.dag_stream, &(p->md.dag_mem_bottom))) ) {
                 return -1;
            }
#else
            /* dag_offset does not support timeouts */
            p->md.dag_mem_top = dag_offset(p->fd, &(p->md.dag_mem_bottom), flags);
#endif /* HAVE_DAG_STREAMS_API */

            if (nonblocking && (p->md.dag_mem_top - p->md.dag_mem_bottom < dag_record_size))
            {
                  /* Pcap is configured to process only available packets, and there aren't any, return immediately. */
                  return 0;
            }
            
            if(!nonblocking &&
               p->md.dag_timeout &&
               (p->md.dag_mem_top - p->md.dag_mem_bottom < dag_record_size))
            {
                  /* Blocking mode, but timeout set and no data has arrived, return anyway.*/
                  return 0;
            }

      }
      
      /* Process the packets. */
      while (p->md.dag_mem_top - p->md.dag_mem_bottom >= dag_record_size) {
            
            unsigned short packet_len = 0;
            int caplen = 0;
            struct pcap_pkthdr      pcap_header;
            
#ifdef HAVE_DAG_STREAMS_API
            dag_record_t *header = (dag_record_t *)(p->md.dag_mem_bottom);
#else
            dag_record_t *header = (dag_record_t *)(p->md.dag_mem_base + p->md.dag_mem_bottom);
#endif /* HAVE_DAG_STREAMS_API */

            u_char *dp = ((u_char *)header); /* + dag_record_size; */
            unsigned short rlen;
 
            /*
             * Has "pcap_breakloop()" been called?
             */
            if (p->break_loop) {
                  /*
                   * Yes - clear the flag that indicates that
                   * it has, and return -2 to indicate that
                   * we were told to break out of the loop.
                   */
                  p->break_loop = 0;
                  return -2;
            }
 
            rlen = ntohs(header->rlen);
            if (rlen < dag_record_size)
            {
                  strncpy(p->errbuf, "dag_read: record too small", PCAP_ERRBUF_SIZE);
                  return -1;
            }
            p->md.dag_mem_bottom += rlen;

            /* Count lost packets. */
            switch((header->type & 0x7f)) {
                  /* in these types the color value overwrites the lctr */
            case TYPE_COLOR_HDLC_POS:
            case TYPE_COLOR_ETH:
            case TYPE_DSM_COLOR_HDLC_POS:
            case TYPE_DSM_COLOR_ETH:
            case TYPE_COLOR_MC_HDLC_POS:
            case TYPE_COLOR_HASH_ETH:
            case TYPE_COLOR_HASH_POS:
                  break;

            default:
                  if (header->lctr) {
                        if (p->md.stat.ps_drop > (UINT_MAX - ntohs(header->lctr))) {
                              p->md.stat.ps_drop = UINT_MAX;
                        } else {
                              p->md.stat.ps_drop += ntohs(header->lctr);
                        }
                  }
            }
            
            if ((header->type & 0x7f) == TYPE_PAD) {
                  continue;
            }

            num_ext_hdr = dag_erf_ext_header_count(dp, rlen);

            /* ERF encapsulation */
            /* The Extensible Record Format is not dropped for this kind of encapsulation, 
             * and will be handled as a pseudo header by the decoding application.
             * The information carried in the ERF header and in the optional subheader (if present)
             * could be merged with the libpcap information, to offer a better decoding.
             * The packet length is
             * o the length of the packet on the link (header->wlen),
             * o plus the length of the ERF header (dag_record_size), as the length of the 
             *   pseudo header will be adjusted during the decoding,
             * o plus the length of the optional subheader (if present).
             *
             * The capture length is header.rlen and the byte stuffing for alignment will be dropped
             * if the capture length is greater than the packet length.
             */
            if (p->linktype == DLT_ERF) {
                  packet_len = ntohs(header->wlen) + dag_record_size;
                  caplen = rlen;
                  switch ((header->type & 0x7f)) {
                  case TYPE_MC_AAL5:
                  case TYPE_MC_ATM:
                  case TYPE_MC_HDLC:
                        packet_len += 4; /* MC header */
                        break;

                  case TYPE_COLOR_HASH_ETH:
                  case TYPE_DSM_COLOR_ETH:
                  case TYPE_COLOR_ETH:
                  case TYPE_ETH:
                        packet_len += 2; /* ETH header */
                        break;
                  } /* switch type */

                  /* Include ERF extension headers */
                  packet_len += (8 * num_ext_hdr);

                  if (caplen > packet_len) {
                        caplen = packet_len;
                  }
            } else {
                  /* Other kind of encapsulation according to the header Type */

                  /* Skip over generic ERF header */
                  dp += dag_record_size;
                  /* Skip over extension headers */
                  dp += 8 * num_ext_hdr;
                  
                  switch((header->type & 0x7f)) {
                  case TYPE_ATM:
                  case TYPE_AAL5:
                        if (header->type == TYPE_AAL5) {
                              packet_len = ntohs(header->wlen);
                              caplen = rlen - dag_record_size;
                        }
                  case TYPE_MC_ATM:
                        if (header->type == TYPE_MC_ATM) {
                              caplen = packet_len = ATM_CELL_SIZE;
                              dp+=4;
                        }
                  case TYPE_MC_AAL5:
                        if (header->type == TYPE_MC_AAL5) {
                              packet_len = ntohs(header->wlen);
                              caplen = rlen - dag_record_size - 4;
                              dp+=4;
                        }
                        if (header->type == TYPE_ATM) {
                              caplen = packet_len = ATM_CELL_SIZE;
                        }
                        if (p->linktype == DLT_SUNATM) {
                              struct sunatm_hdr *sunatm = (struct sunatm_hdr *)dp;
                              unsigned long rawatm;
                              
                              rawatm = ntohl(*((unsigned long *)dp));
                              sunatm->vci = htons((rawatm >>  4) & 0xffff);
                              sunatm->vpi = (rawatm >> 20) & 0x00ff;
                              sunatm->flags = ((header->flags.iface & 1) ? 0x80 : 0x00) | 
                                    ((sunatm->vpi == 0 && sunatm->vci == htons(5)) ? 6 :
                                     ((sunatm->vpi == 0 && sunatm->vci == htons(16)) ? 5 : 
                                      ((dp[ATM_HDR_SIZE] == 0xaa &&
                                        dp[ATM_HDR_SIZE+1] == 0xaa &&
                                        dp[ATM_HDR_SIZE+2] == 0x03) ? 2 : 1)));

                        } else {
                              packet_len -= ATM_HDR_SIZE;
                              caplen -= ATM_HDR_SIZE;
                              dp += ATM_HDR_SIZE;
                        }
                        break;

                  case TYPE_COLOR_HASH_ETH:
                  case TYPE_DSM_COLOR_ETH:
                  case TYPE_COLOR_ETH:
                  case TYPE_ETH:
                        packet_len = ntohs(header->wlen);
                        packet_len -= (p->md.dag_fcs_bits >> 3);
                        caplen = rlen - dag_record_size - 2;
                        if (caplen > packet_len) {
                              caplen = packet_len;
                        }
                        dp += 2;
                        break;

                  case TYPE_COLOR_HASH_POS:
                  case TYPE_DSM_COLOR_HDLC_POS:
                  case TYPE_COLOR_HDLC_POS:
                  case TYPE_HDLC_POS:
                        packet_len = ntohs(header->wlen);
                        packet_len -= (p->md.dag_fcs_bits >> 3);
                        caplen = rlen - dag_record_size;
                        if (caplen > packet_len) {
                              caplen = packet_len;
                        }
                        break;

                  case TYPE_COLOR_MC_HDLC_POS:
                  case TYPE_MC_HDLC:
                        packet_len = ntohs(header->wlen);
                        packet_len -= (p->md.dag_fcs_bits >> 3);
                        caplen = rlen - dag_record_size - 4;
                        if (caplen > packet_len) {
                              caplen = packet_len;
                        }
                        /* jump the MC_HDLC_HEADER */
                        dp += 4;
#ifdef DLT_MTP2_WITH_PHDR
                        if (p->linktype == DLT_MTP2_WITH_PHDR) {
                              /* Add the MTP2 Pseudo Header */
                              caplen += MTP2_HDR_LEN;
                              packet_len += MTP2_HDR_LEN;
                              
                              TempPkt[MTP2_SENT_OFFSET] = 0;
                              TempPkt[MTP2_ANNEX_A_USED_OFFSET] = MTP2_ANNEX_A_USED_UNKNOWN;
                              *(TempPkt+MTP2_LINK_NUMBER_OFFSET) = ((header->rec.mc_hdlc.mc_header>>16)&0x01);
                              *(TempPkt+MTP2_LINK_NUMBER_OFFSET+1) = ((header->rec.mc_hdlc.mc_header>>24)&0xff);
                              memcpy(TempPkt+MTP2_HDR_LEN, dp, caplen);
                              dp = TempPkt;
                        }
#endif
                        break;

                  case TYPE_IPV4:
                        packet_len = ntohs(header->wlen);
                        caplen = rlen - dag_record_size;
                        if (caplen > packet_len) {
                              caplen = packet_len;
                        }
                        break;

                  default:
                        /* Unhandled ERF type.
                         * Ignore rather than generating error
                         */
                        continue;
                  } /* switch type */

                  /* Skip over extension headers */
                  caplen -= (8 * num_ext_hdr);

            } /* ERF encapsulation */
            
            if (caplen > p->snapshot)
                  caplen = p->snapshot;

            /* Run the packet filter if there is one. */
            if ((p->fcode.bf_insns == NULL) || bpf_filter(p->fcode.bf_insns, dp, packet_len, caplen)) {
                  
                  /* convert between timestamp formats */
                  register unsigned long long ts;
                        
                  if (IS_BIGENDIAN()) {
                        ts = SWAPLL(header->ts);
                  } else {
                        ts = header->ts;
                  }

                  pcap_header.ts.tv_sec = ts >> 32;
                  ts = (ts & 0xffffffffULL) * 1000000;
                  ts += 0x80000000; /* rounding */
                  pcap_header.ts.tv_usec = ts >> 32;        
                  if (pcap_header.ts.tv_usec >= 1000000) {
                        pcap_header.ts.tv_usec -= 1000000;
                        pcap_header.ts.tv_sec++;
                  }

                  /* Fill in our own header data */
                  pcap_header.caplen = caplen;
                  pcap_header.len = packet_len;
      
                  /* Count the packet. */
                  p->md.stat.ps_recv++;
      
                  /* Call the user supplied callback function */
                  callback(user, &pcap_header, dp);
      
                  /* Only count packets that pass the filter, for consistency with standard Linux behaviour. */
                  processed++;
                  if (processed == cnt && cnt > 0)
                  {
                        /* Reached the user-specified limit. */
                        return cnt;
                  }
            }
      }

      return processed;
}

static int
dag_inject(pcap_t *p, const void *buf _U_, size_t size _U_)
{
      strlcpy(p->errbuf, "Sending packets isn't supported on DAG cards",
          PCAP_ERRBUF_SIZE);
      return (-1);
}

/*
 *  Get a handle for a live capture from the given DAG device.  Passing a NULL
 *  device will result in a failure.  The promisc flag is ignored because DAG
 *  cards are always promiscuous.  The to_ms parameter is used in setting the
 *  API polling parameters.
 *  
 *  snaplen is now also ignored, until we get per-stream slen support. Set
 *  slen with approprite DAG tool BEFORE pcap_activate().
 *
 *  See also pcap(3).
 */
static int dag_activate(pcap_t* handle)
{
#if 0
      char conf[30]; /* dag configure string */
#endif
      char *s;
      int n;
      daginf_t* daginf;
      char * newDev = NULL;
      char * device = handle->opt.source;
#ifdef HAVE_DAG_STREAMS_API
      uint32_t mindata;
      struct timeval maxwait;
      struct timeval poll;
#endif

      if (device == NULL) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "device is NULL: %s", pcap_strerror(errno));
            return -1;
      }

      /* Initialize some components of the pcap structure. */

#ifdef HAVE_DAG_STREAMS_API
      newDev = (char *)malloc(strlen(device) + 16);
      if (newDev == NULL) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate string for device name: %s\n", pcap_strerror(errno));
            goto fail;
      }
      
      /* Parse input name to get dag device and stream number if provided */
      if (dag_parse_name(device, newDev, strlen(device) + 16, &handle->md.dag_stream) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_parse_name: %s\n", pcap_strerror(errno));
            goto fail;
      }
      device = newDev;

      if (handle->md.dag_stream%2) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_parse_name: tx (even numbered) streams not supported for capture\n");
            goto fail;
      }
#else
      if (strncmp(device, "/dev/", 5) != 0) {
            newDev = (char *)malloc(strlen(device) + 5);
            if (newDev == NULL) {
                  snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate string for device name: %s\n", pcap_strerror(errno));
                  goto fail;
            }
            strcpy(newDev, "/dev/");
            strcat(newDev, device);
            device = newDev;
      }
#endif /* HAVE_DAG_STREAMS_API */

      /* setup device parameters */
      if((handle->fd = dag_open((char *)device)) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_open %s: %s", device, pcap_strerror(errno));
            goto fail;
      }

#ifdef HAVE_DAG_STREAMS_API
      /* Open requested stream. Can fail if already locked or on error */
      if (dag_attach_stream(handle->fd, handle->md.dag_stream, 0, 0) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_attach_stream: %s\n", pcap_strerror(errno));
            goto failclose;
      }

      /* Set up default poll parameters for stream
       * Can be overridden by pcap_set_nonblock()
       */
      if (dag_get_stream_poll(handle->fd, handle->md.dag_stream,
                        &mindata, &maxwait, &poll) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_get_stream_poll: %s\n", pcap_strerror(errno));
            goto faildetach;
      }
      
      /* Amount of data to collect in Bytes before calling callbacks.
       * Important for efficiency, but can introduce latency
       * at low packet rates if to_ms not set!
       */
      mindata = 65536;

      /* Obey md.timeout (was to_ms) if supplied. This is a good idea!
       * Recommend 10-100ms. Calls will time out even if no data arrived.
       */
      maxwait.tv_sec = handle->md.timeout/1000;
      maxwait.tv_usec = (handle->md.timeout%1000) * 1000;

      if (dag_set_stream_poll(handle->fd, handle->md.dag_stream,
                        mindata, &maxwait, &poll) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_set_stream_poll: %s\n", pcap_strerror(errno));
            goto faildetach;
      }
            
#else
      if((handle->md.dag_mem_base = dag_mmap(handle->fd)) == MAP_FAILED) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,"dag_mmap %s: %s\n", device, pcap_strerror(errno));
            goto failclose;
      }

#endif /* HAVE_DAG_STREAMS_API */

        /* XXX Not calling dag_configure() to set slen; this is unsafe in
       * multi-stream environments as the gpp config is global.
         * Once the firmware provides 'per-stream slen' this can be supported
       * again via the Config API without side-effects */
#if 0
      /* set the card snap length to the specified snaplen parameter */
      /* This is a really bad idea, as different cards have different
       * valid slen ranges. Should fix in Config API. */
      if (handle->snapshot == 0 || handle->snapshot > MAX_DAG_SNAPLEN) {
            handle->snapshot = MAX_DAG_SNAPLEN;
      } else if (snaplen < MIN_DAG_SNAPLEN) {
            handle->snapshot = MIN_DAG_SNAPLEN;
      }
      /* snap len has to be a multiple of 4 */
      snprintf(conf, 30, "varlen slen=%d", (snaplen + 3) & ~3); 

      if(dag_configure(handle->fd, conf) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,"dag_configure %s: %s\n", device, pcap_strerror(errno));
            goto faildetach;
      }
#endif      
      
#ifdef HAVE_DAG_STREAMS_API
      if(dag_start_stream(handle->fd, handle->md.dag_stream) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_start_stream %s: %s\n", device, pcap_strerror(errno));
            goto faildetach;
      }
#else
      if(dag_start(handle->fd) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dag_start %s: %s\n", device, pcap_strerror(errno));
            goto failclose;
      }
#endif /* HAVE_DAG_STREAMS_API */

      /*
       * Important! You have to ensure bottom is properly
       * initialized to zero on startup, it won't give you
       * a compiler warning if you make this mistake!
       */
      handle->md.dag_mem_bottom = 0;
      handle->md.dag_mem_top = 0;

      /*
       * Find out how many FCS bits we should strip.
       * First, query the card to see if it strips the FCS.
       */
      daginf = dag_info(handle->fd);
      if ((0x4200 == daginf->device_code) || (0x4230 == daginf->device_code)) {
            /* DAG 4.2S and 4.23S already strip the FCS.  Stripping the final word again truncates the packet. */
            handle->md.dag_fcs_bits = 0;

            /* Note that no FCS will be supplied. */
            handle->linktype_ext = LT_FCS_DATALINK_EXT(0);
      } else {
            /*
             * Start out assuming it's 32 bits.
             */
            handle->md.dag_fcs_bits = 32;

            /* Allow an environment variable to override. */
            if ((s = getenv("ERF_FCS_BITS")) != NULL) {
                  if ((n = atoi(s)) == 0 || n == 16 || n == 32) {
                        handle->md.dag_fcs_bits = n;
                  } else {
                        snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
                              "pcap_activate %s: bad ERF_FCS_BITS value (%d) in environment\n", device, n);
                        goto failstop;
                  }
            }

            /*
             * Did the user request that they not be stripped?
             */
            if ((s = getenv("ERF_DONT_STRIP_FCS")) != NULL) {
                  /* Yes.  Note the number of bytes that will be
                     supplied. */
                  handle->linktype_ext = LT_FCS_DATALINK_EXT(handle->md.dag_fcs_bits/16);

                  /* And don't strip them. */
                  handle->md.dag_fcs_bits = 0;
            }
      }

      handle->md.dag_timeout  = handle->md.timeout;

      handle->linktype = -1;
      if (dag_get_datalink(handle) < 0)
            goto failstop;
      
      handle->bufsize = 0;

      if (new_pcap_dag(handle) < 0) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "new_pcap_dag %s: %s\n", device, pcap_strerror(errno));
            goto failstop;
      }

      /*
       * "select()" and "poll()" don't work on DAG device descriptors.
       */
      handle->selectable_fd = -1;

      if (newDev != NULL) {
            free((char *)newDev);
      }

      handle->read_op = dag_read;
      handle->inject_op = dag_inject;
      handle->setfilter_op = dag_setfilter;
      handle->setdirection_op = NULL; /* Not implemented.*/
      handle->set_datalink_op = dag_set_datalink;
      handle->getnonblock_op = pcap_getnonblock_fd;
      handle->setnonblock_op = dag_setnonblock;
      handle->stats_op = dag_stats;
      handle->cleanup_op = dag_platform_cleanup;
      handle->md.stat.ps_drop = 0;
      handle->md.stat.ps_recv = 0;
      return 0;

#ifdef HAVE_DAG_STREAMS_API 
failstop:
      if (dag_stop_stream(handle->fd, handle->md.dag_stream) < 0) {
            fprintf(stderr,"dag_stop_stream: %s\n", strerror(errno));
      }
      
faildetach:
      if (dag_detach_stream(handle->fd, handle->md.dag_stream) < 0)
            fprintf(stderr,"dag_detach_stream: %s\n", strerror(errno));
#else
failstop:
      if (dag_stop(handle->fd) < 0)
            fprintf(stderr,"dag_stop: %s\n", strerror(errno));
#endif /* HAVE_DAG_STREAMS_API */
      
failclose:
      if (dag_close(handle->fd) < 0)
            fprintf(stderr,"dag_close: %s\n", strerror(errno));
      delete_pcap_dag(handle);

fail:
      pcap_cleanup_live_common(handle);
      if (newDev != NULL) {
            free((char *)newDev);
      }

      return PCAP_ERROR;
}

pcap_t *dag_create(const char *device, char *ebuf)
{
      pcap_t *p;

      p = pcap_create_common(device, ebuf);
      if (p == NULL)
            return NULL;

      p->activate_op = dag_activate;
      return p;
}

static int
dag_stats(pcap_t *p, struct pcap_stat *ps) {
      /* This needs to be filled out correctly.  Hopefully a dagapi call will
             provide all necessary information.
      */
      /*p->md.stat.ps_recv = 0;*/
      /*p->md.stat.ps_drop = 0;*/
      
      *ps = p->md.stat;
 
      return 0;
}

/*
 * Previously we just generated a list of all possible names and let
 * pcap_add_if() attempt to open each one, but with streams this adds up
 * to 81 possibilities which is inefficient.
 *
 * Since we know more about the devices we can prune the tree here.
 * pcap_add_if() will still retest each device but the total number of
 * open attempts will still be much less than the naive approach.
 */
int
dag_platform_finddevs(pcap_if_t **devlistp, char *errbuf)
{
      char name[12];    /* XXX - pick a size */
      int ret = 0;
      int c;
      char dagname[DAGNAME_BUFSIZE];
      int dagstream;
      int dagfd;

      /* Try all the DAGs 0-9 */
      for (c = 0; c < 9; c++) {
            snprintf(name, 12, "dag%d", c);
            if (-1 == dag_parse_name(name, dagname, DAGNAME_BUFSIZE, &dagstream))
            {
                  return -1;
            }
            if ( (dagfd = dag_open(dagname)) >= 0 ) {
                  if (pcap_add_if(devlistp, name, 0, NULL, errbuf) == -1) {
                        /*
                         * Failure.
                         */
                        ret = -1;
                  }
#ifdef HAVE_DAG_STREAMS_API
                  {
                        int stream, rxstreams;
                        rxstreams = dag_rx_get_stream_count(dagfd);
                        for(stream=0;stream<16;stream+=2) {
                              if (0 == dag_attach_stream(dagfd, stream, 0, 0)) {
                                    dag_detach_stream(dagfd, stream);

                                    snprintf(name,  10, "dag%d:%d", c, stream);
                                    if (pcap_add_if(devlistp, name, 0, NULL, errbuf) == -1) {
                                          /*
                                           * Failure.
                                           */
                                          ret = -1;
                                    }
                              }
                        }                       
                  }
#endif  /* HAVE_DAG_STREAMS_API */
                  dag_close(dagfd);
            }

      }
      return (ret);
}

/*
 * Installs the given bpf filter program in the given pcap structure.  There is
 * no attempt to store the filter in kernel memory as that is not supported
 * with DAG cards.
 */
static int
dag_setfilter(pcap_t *p, struct bpf_program *fp)
{
      if (!p)
            return -1;
      if (!fp) {
            strncpy(p->errbuf, "setfilter: No filter specified",
                  sizeof(p->errbuf));
            return -1;
      }

      /* Make our private copy of the filter */

      if (install_bpf_program(p, fp) < 0)
            return -1;

      p->md.use_bpf = 0;

      return (0);
}

static int
dag_set_datalink(pcap_t *p, int dlt)
{
      p->linktype = dlt;

      return (0);
}

static int
dag_setnonblock(pcap_t *p, int nonblock, char *errbuf)
{
      /*
       * Set non-blocking mode on the FD.
       * XXX - is that necessary?  If not, don't bother calling it,
       * and have a "dag_getnonblock()" function that looks at
       * "p->md.dag_offset_flags".
       */
      if (pcap_setnonblock_fd(p, nonblock, errbuf) < 0)
            return (-1);
#ifdef HAVE_DAG_STREAMS_API
      {
            uint32_t mindata;
            struct timeval maxwait;
            struct timeval poll;
            
            if (dag_get_stream_poll(p->fd, p->md.dag_stream,
                              &mindata, &maxwait, &poll) < 0) {
                  snprintf(errbuf, PCAP_ERRBUF_SIZE, "dag_get_stream_poll: %s\n", pcap_strerror(errno));
                  return -1;
            }
            
            /* Amount of data to collect in Bytes before calling callbacks.
             * Important for efficiency, but can introduce latency
             * at low packet rates if to_ms not set!
             */
            if(nonblock)
                  mindata = 0;
            else
                  mindata = 65536;
            
            if (dag_set_stream_poll(p->fd, p->md.dag_stream,
                              mindata, &maxwait, &poll) < 0) {
                  snprintf(errbuf, PCAP_ERRBUF_SIZE, "dag_set_stream_poll: %s\n", pcap_strerror(errno));
                  return -1;
            }
      }
#endif /* HAVE_DAG_STREAMS_API */
      if (nonblock) {
            p->md.dag_offset_flags |= DAGF_NONBLOCK;
      } else {
            p->md.dag_offset_flags &= ~DAGF_NONBLOCK;
      }
      return (0);
}
            
static int
dag_get_datalink(pcap_t *p)
{
      int index=0, dlt_index=0;
      uint8_t types[255];

      memset(types, 0, 255);

      if (p->dlt_list == NULL && (p->dlt_list = malloc(255*sizeof(*(p->dlt_list)))) == NULL) {
            (void)snprintf(p->errbuf, sizeof(p->errbuf), "malloc: %s", pcap_strerror(errno));
            return (-1);
      }

      p->linktype = 0;

#ifdef HAVE_DAG_GET_STREAM_ERF_TYPES
      /* Get list of possible ERF types for this card */
      if (dag_get_stream_erf_types(p->fd, p->md.dag_stream, types, 255) < 0) {
            snprintf(p->errbuf, sizeof(p->errbuf), "dag_get_stream_erf_types: %s", pcap_strerror(errno));
            return (-1);            
      }
      
      while (types[index]) {

#elif defined HAVE_DAG_GET_ERF_TYPES
      /* Get list of possible ERF types for this card */
      if (dag_get_erf_types(p->fd, types, 255) < 0) {
            snprintf(p->errbuf, sizeof(p->errbuf), "dag_get_erf_types: %s", pcap_strerror(errno));
            return (-1);            
      }
      
      while (types[index]) {
#else
      /* Check the type through a dagapi call. */
      types[index] = dag_linktype(p->fd);

      {
#endif
            switch((types[index] & 0x7f)) {

            case TYPE_HDLC_POS:
            case TYPE_COLOR_HDLC_POS:
            case TYPE_DSM_COLOR_HDLC_POS:
            case TYPE_COLOR_HASH_POS:

                  if (p->dlt_list != NULL) {
                        p->dlt_list[dlt_index++] = DLT_CHDLC;
                        p->dlt_list[dlt_index++] = DLT_PPP_SERIAL;
                        p->dlt_list[dlt_index++] = DLT_FRELAY;
                  }
                  if(!p->linktype)
                        p->linktype = DLT_CHDLC;
                  break;

            case TYPE_ETH:
            case TYPE_COLOR_ETH:
            case TYPE_DSM_COLOR_ETH:
            case TYPE_COLOR_HASH_ETH:
                  /*
                   * This is (presumably) a real Ethernet capture; give it a
                   * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
                   * that an application can let you choose it, in case you're
                   * capturing DOCSIS traffic that a Cisco Cable Modem
                   * Termination System is putting out onto an Ethernet (it
                   * doesn't put an Ethernet header onto the wire, it puts raw
                   * DOCSIS frames out on the wire inside the low-level
                   * Ethernet framing).
                   */
                  if (p->dlt_list != NULL) {
                        p->dlt_list[dlt_index++] = DLT_EN10MB;
                        p->dlt_list[dlt_index++] = DLT_DOCSIS;
                  }
                  if(!p->linktype)
                        p->linktype = DLT_EN10MB;
                  break;

            case TYPE_ATM: 
            case TYPE_AAL5:
            case TYPE_MC_ATM:
            case TYPE_MC_AAL5:
                  if (p->dlt_list != NULL) {
                        p->dlt_list[dlt_index++] = DLT_ATM_RFC1483;
                        p->dlt_list[dlt_index++] = DLT_SUNATM;
                  }
                  if(!p->linktype)
                        p->linktype = DLT_ATM_RFC1483;
                  break;

            case TYPE_COLOR_MC_HDLC_POS:
            case TYPE_MC_HDLC:
                  if (p->dlt_list != NULL) {
                        p->dlt_list[dlt_index++] = DLT_CHDLC;
                        p->dlt_list[dlt_index++] = DLT_PPP_SERIAL;
                        p->dlt_list[dlt_index++] = DLT_FRELAY;
                        p->dlt_list[dlt_index++] = DLT_MTP2;
                        p->dlt_list[dlt_index++] = DLT_MTP2_WITH_PHDR;
                        p->dlt_list[dlt_index++] = DLT_LAPD;
                  }
                  if(!p->linktype)
                        p->linktype = DLT_CHDLC;
                  break;

            case TYPE_IPV4:
                  if(!p->linktype)
                        p->linktype = DLT_RAW;
                  break;

            case TYPE_LEGACY:
            case TYPE_MC_RAW:
            case TYPE_MC_RAW_CHANNEL:
            case TYPE_IP_COUNTER:
            case TYPE_TCP_FLOW_COUNTER:
            case TYPE_INFINIBAND:
            case TYPE_IPV6:
            default:
                  /* Libpcap cannot deal with these types yet */
                  /* Add no DLTs, but still covered by DLT_ERF */
                  break;

            } /* switch */
            index++;
      }

      p->dlt_list[dlt_index++] = DLT_ERF;

      p->dlt_count = dlt_index;

      if(!p->linktype)
            p->linktype = DLT_ERF;

      return p->linktype;
}

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