Re: Patch for Endace DAG card support in libpcap

[Jesper Peterson <jesper () endace com>]

Attached is a replacement pcap-dag.c file superceeding the one submitted 
in a patch on this list on May 29. Is the DAG support patch still under 
considereation or has it been rejected? Would it be accepted in a 
different form?

Thanks.

--
Jesper Peterson, Senior Software Developer
http://www.endace.com, +64 7 839 0540

/*
 * 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.
 *
 * Author: Richard Littin, Sean Irvine ({richard,sean}@reeltwo.com)
 *
 * Modifications:
 *   2003 May - Jesper Peterson <support () endace com>
 *              Code shuffled around to suit fad-xxx.c structure
 *              Added atexit() handler to stop DAG if application is too lazy
 */

#ifndef lint
static const char rcsid[] =
    "@(#) $Header$ (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 <sys/mman.h>
#include <sys/socket.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>

#define MAX_DAG_SNAPLEN 2040

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

static pcap_dag_node_t *pcap_dags = NULL;
static int atexit_handler_installed = 0;

#ifdef DAG_ONLY
/* This code is reguired when compiling for a DAG device only. */
#include "pcap-dag.h"

/* Replace dag function names with pcap equivalent. */
#define dag_stats pcap_stats
#define dag_read pcap_read
#define dag_open_live pcap_open_live
#define dag_platform_finddevs pcap_platform_finddevs
#define dag_setfilter pcap_setfilter
#define dag_set_datalink_platform pcap_set_datalink_platform
#define dag_platform_close pcap_platform_close
#endif /* DAG_ONLY */

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 and frees dynamic memory held
 * in the pcap_t structure.
 */

void dag_platform_close(pcap_t *p) {

#ifdef linux
  if (p != NULL && p->md.is_dag && p->md.device != NULL) {
    if(dag_stop(p->fd) < 0)
      fprintf(stderr,"dag_stop %s: %s\n", p->md.device, strerror(errno));
    if(dag_close(p->fd) < 0)
      fprintf(stderr,"dag_close %s: %s\n", p->md.device, strerror(errno));
    
    free(p->md.device);
  }
#else
  if (p != NULL && p->md.is_dag) {
    if(dag_stop(p->fd) < 0)
      fprintf(stderr,"dag_stop: %s\n", strerror(errno));
    if(dag_close(p->fd) < 0)
      fprintf(stderr,"dag_close: %s\n", strerror(errno));
  }
#endif
  delete_pcap_dag(p);
}

static void atexit_handler(void) {
  while (pcap_dags != NULL) {
    dag_platform_close(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;

  return 0;
}

/*
 * Get pointer to the ERF header for the next packet in the input
 * stream. This function blocks until a packet becomes available.
 */
static dag_record_t *get_next_dag_header(pcap_t *p) {
  register dag_record_t *record;
  int rlen;

  if (p->md.dag_mem_top - p->md.dag_mem_bottom < dag_record_size) {
    p->md.dag_mem_top = dag_offset(p->fd, &(p->md.dag_mem_bottom), 0);
  }

  record = (dag_record_t *)(p->md.dag_mem_base + p->md.dag_mem_bottom);
  rlen = ntohs(record->rlen);
  while (p->md.dag_mem_top - p->md.dag_mem_bottom < rlen) {
    p->md.dag_mem_top = dag_offset(p->fd, &(p->md.dag_mem_bottom), 0);
    record = (dag_record_t *)(p->md.dag_mem_base + p->md.dag_mem_bottom);
    rlen = ntohs(record->rlen);
  }

  p->md.dag_mem_bottom += rlen;
  
  return record;
}

/* Size of payload in ATM packets */
#define ATM_CAPTURE_SIZE 48

/* Size of payload of Ethernet packet */
#define ETHERNET_LENGTH(h) min(ntohs((h)->wlen) - 4, ntohs((h)->rlen) - dag_record_size - 2 - (ntohs((h)->wlen) & 0x3))

/* Size of HDLC packet */
#define HDLC_LENGTH(h) min(ntohs((h)->wlen) - 4, ntohs((h)->rlen) - dag_record_size)

#ifndef min
#define min(a, b) ((a) > (b) ? (b) : (a))
#endif

/*
 * Swap byte ordering of unsigned long long on a big endian
 * machine.
 */
static unsigned long long swapll(unsigned long long ull) {
#if (BYTE_ORDER == BIG_ENDIAN)
  return ((ull & 0xff00000000000000LL) >> 56) |
    ((ull & 0x00ff000000000000LL) >> 40) |
    ((ull & 0x0000ff0000000000LL) >> 24) |
    ((ull & 0x000000ff00000000LL) >>  8) |
    ((ull & 0x00000000ff000000LL) <<  8) |
    ((ull & 0x0000000000ff0000LL) << 24) |
    ((ull & 0x000000000000ff00LL) << 40) |
    ((ull & 0x00000000000000ffLL) << 56) ;
#else
  return ull;
#endif
}

/*
 *  Read at most max_packets from the capture stream and call the callback
 *  for each of them. Returns the number of packets handled or -1 if an
 *  error occured.  A blocking 
 */
int dag_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user) {
  u_char                *dp = NULL;
  int                   packet_len = 0, caplen = 0;
  struct pcap_pkthdr    pcap_header;

  dag_record_t *header;
  register unsigned long long ts;
 
  /* Receive a single packet from the kernel */
  header = get_next_dag_header(p);
  dp = ((u_char *)header) + dag_record_size;

  switch(header->type) {
  case TYPE_ATM:
    packet_len = ATM_CAPTURE_SIZE;
    caplen = ATM_CAPTURE_SIZE;
    break;
  case TYPE_ETH:
    packet_len = ntohs(header->wlen);
    caplen = ETHERNET_LENGTH(header);
    dp += 2;
    break;
  case TYPE_HDLC_POS:
    packet_len = ntohs(header->wlen);
    caplen = HDLC_LENGTH(header);
    break;
  }
 
  if (caplen > p->snapshot)
    caplen = p->snapshot;

  /* Run the packet filter if not using kernel filter */
  if (p->fcode.bf_insns) {
    if (bpf_filter(p->fcode.bf_insns, dp, packet_len, caplen) == 0) {
      /* rejected by filter */
      return 0;
    }
  }

  // convert between timestamp formats
  ts = swapll(header->ts);
  pcap_header.ts.tv_sec  = ts >> 32;
  ts = ((ts &  0xffffffffULL) * 1000 * 1000);
  ts += (ts & 0x80000000ULL) << 1; /* 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 += 1;
  }

  /* 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);
  
  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 becuase DAG
 *  cards are always promiscuous.  The to_ms parameter is also ignored as it is
 *  not supported in hardware.
 *  
 *  See also pcap(3).
 */
pcap_t *dag_open_live(const char *device, int snaplen, int promisc, int to_ms, char *ebuf) {
  char conf[30]; /* dag configure string */
  pcap_t *handle;
  
  if (device == NULL) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE, "device is NULL: %s", pcap_strerror(errno));
    return NULL;
  }
  /* Allocate a handle for this session. */

  handle = malloc(sizeof(*handle));
  if (handle == NULL) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc %s: %s", device, pcap_strerror(errno));
    return NULL;
  }
  
  /* Initialize some components of the pcap structure. */
  
  memset(handle, 0, sizeof(*handle));

  if (strstr(device, "/dev") == NULL) {
    char * newDev = (char *)malloc(strlen(device) + 6);
    newDev[0] = '\0';
    strcat(newDev, "/dev/");
    strcat(newDev,device);
    device = newDev;
  }

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

  /* set the card snap length as specified by the specified snaplen parameter */
  if (snaplen > MAX_DAG_SNAPLEN) {
    snaplen = MAX_DAG_SNAPLEN;
  }
  snprintf(conf, 30, "varlen slen=%d", (snaplen % 4) ? (snaplen + 3) & ~3 : snaplen); // snap len has to be a multiple 
of 4
  fprintf(stderr, "Configuring DAG with '%s'.\n", conf);
  if(dag_configure(handle->fd, conf) < 0) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE,"dag_configure %s: %s\n", device, pcap_strerror(errno));
    return NULL;
  }
  
  if((handle->md.dag_mem_base = dag_mmap(handle->fd)) == MAP_FAILED) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE,"dag_mmap %s: %s\n", device, pcap_strerror(errno));
    return NULL;
  }
  
  if(dag_start(handle->fd) < 0) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_start %s: %s\n", device, pcap_strerror(errno));
    return NULL;
  }

  /*
   * 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;
  handle->md.is_dag = 1;

  handle->snapshot      = snaplen;
  //handle->md.timeout  = to_ms;

#ifdef linux
  if (device) {
    handle->md.device = strdup(device);
  }

  if (handle->md.device == NULL) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE, "str_dup %s: %s\n", device, pcap_strerror(errno));
    free(handle);
    return NULL;
  }
#endif

  /* set link type */
  
  /* Check the type through a dagapi call.
  */
  switch(dag_linktype(handle->fd)) {
  case TYPE_HDLC_POS:
    handle->linktype = DLT_CHDLC;
    fprintf(stderr, "Set DAG linktype to %d (DLT_CHDLC)\n", handle->linktype);
    break;
  case TYPE_ETH:
    handle->linktype = DLT_EN10MB;
    fprintf(stderr, "Set DAG linktype to %d (DLT_EN10MB)\n", handle->linktype);
    break;
  case TYPE_ATM: 
    handle->linktype = DLT_ATM_RFC1483;
    fprintf(stderr, "Set DAG linktype to %d (DLT_ATM_RFC1483)\n", handle->linktype);
    break;
  case TYPE_LEGACY:
    handle->linktype = DLT_NULL;
    fprintf(stderr, "Set DAG linktype to %d (DLT_NULL)\n", handle->linktype);
    break;
  default:
    snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_open_live %s: unknown linktype %d\n", device, dag_linktype(handle->fd));
    return NULL;
  }
  
  handle->bufsize = 0;//handle->snapshot;

  if (new_pcap_dag(handle) < 0) {
    snprintf(ebuf, PCAP_ERRBUF_SIZE, "new_pcap_dag %s: %s\n", device, pcap_strerror(errno));
    return NULL;
  }

  return handle;
}

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;
}

/*
 * Get from "/proc/dag" all interfaces listed there; if they're
 * already in the list of interfaces we have, that won't add another
 * instance, but if they're not, that'll add them.
 *
 * We don't bother getting any addresses for them.
 *
 * We also don't fail if we couldn't open "/proc/dag"; we just leave
 * the list of interfaces as is.
 */
int
dag_platform_finddevs(pcap_if_t **devlistp, char *errbuf)
{
  FILE *proc_dag_f;
  char linebuf[512];
  int linenum;
  unsigned char *p;
  char name[512];       /* XXX - pick a size */
  char *q, *saveq;
  struct ifreq ifrflags;
  int ret = 0;

  /* Quick exit if /proc/dag not readable */
  proc_dag_f = fopen("/proc/dag", "r");
  if (proc_dag_f == NULL)
  {
    int i, fd;
    char dev[16] = "dagx";

    for (i = '0'; ret == 0 && i <= '9'; i++) {
      dev[3] = i;
      if (pcap_add_if(devlistp, dev, 0, NULL, errbuf) == -1) {
        /*
         * Failure.
         */
        ret = -1;
      }
    }
          
    return (ret);
  }

  for (linenum = 1;
        fgets(linebuf, sizeof linebuf, proc_dag_f) != NULL; linenum++) {
    
    /*
     * Skip the first two lines - they're headers.
     */
    if (linenum <= 2)
      continue;

    p = &linebuf[0];

    if (*p == '\0' || *p == '\n' || *p != 'D')
      continue;  /* not a Dag line */

    /*
     * Get the interface name.
     */
    q = &name[0];
    while (*p != '\0' && *p != ':') {
      if (*p != ' ')
        *q++ = tolower(*p++);
      else
        p++;
    }
    *q = '\0';

    /*
     * Add an entry for this interface, with no addresses.
     */
    p[strlen(p) - 1] = '\0'; /* get rid of \n */
    if (pcap_add_if(devlistp, name, 0, strdup(p + 2), errbuf) == -1) {
      /*
       * Failure.
       */
      ret = -1;
      break;
    }
  }
  if (ret != -1) {
    /*
     * Well, we didn't fail for any other reason; did we
     * fail due to an error reading the file?
     */
    if (ferror(proc_dag_f)) {
      (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
          "Error reading /proc/dag: %s",
          pcap_strerror(errno));
      ret = -1;
    }
  }

  (void)fclose(proc_dag_f);
  return (ret);
}

/*
 * Installs the gven 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.
 */
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) {
    snprintf(p->errbuf, sizeof(p->errbuf),
             "malloc: %s", pcap_strerror(errno));
    return -1;
  }

  p->md.use_bpf = 0;

  return (0);
}

int
dag_set_datalink_platform(pcap_t *p, int dlt)
{
        return (0);
}