The Tcpdump Group git mirrors - libpcap/blob - pcap-dag.c

   1 /*
   2  * pcap-dag.c: Packet capture interface for Endace DAG card.
   3  *
   4  * The functionality of this code attempts to mimic that of pcap-linux as much
   5  * as possible.  This code is compiled in several different ways depending on
   6  * whether DAG_ONLY and HAVE_DAG_API are defined.  If HAVE_DAG_API is not
   7  * defined it should not get compiled in, otherwise if DAG_ONLY is defined then
   8  * the 'dag_' function calls are renamed to 'pcap_' equivalents.  If DAG_ONLY
   9  * is not defined then nothing is altered - the dag_ functions will be
  10  * called as required from their pcap-linux/bpf equivalents.
  11  *
  12  * Author: Richard Littin, Sean Irvine ({richard,sean}@reeltwo.com)
  13  *
  14  * Modifications:
  15  *   2003 May - Jesper Peterson <support@endace.com>
  16  *              Code shuffled around to suit fad-xxx.c structure
  17  *              Added atexit() handler to stop DAG if application is too lazy
  18  */
  19
  20 #ifndef lint
  21 static const char rcsid[] =
  22     "@(#) $Header: /tcpdump/master/libpcap/pcap-dag.c,v 1.5 2003-07-25 05:07:01 guy Exp $ (LBL)";
  23 #endif
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28
  29 #include <sys/param.h>                  /* optionally get BSD define */
  30
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <errno.h>
  34
  35 #include "pcap-int.h"
  36
  37 #include <sys/mman.h>
  38 #include <sys/socket.h>
  39
  40 struct mbuf;            /* Squelch compiler warnings on some platforms for */
  41 struct rtentry;         /* declarations in <net/if.h> */
  42 #include <net/if.h>
  43
  44 #include <dagnew.h>
  45 #include <dagapi.h>
  46
  47 #define MAX_DAG_SNAPLEN 2040
  48
  49 typedef struct pcap_dag_node {
  50   struct pcap_dag_node *next;
  51   pcap_t *p;
  52 } pcap_dag_node_t;
  53
  54 static pcap_dag_node_t *pcap_dags = NULL;
  55 static int atexit_handler_installed = 0;
  56
  57 #ifdef DAG_ONLY
  58 /* This code is reguired when compiling for a DAG device only. */
  59 #include "pcap-dag.h"
  60
  61 /* Replace dag function names with pcap equivalent. */
  62 #define dag_read pcap_read
  63 #define dag_open_live pcap_open_live
  64 #define dag_platform_finddevs pcap_platform_finddevs
  65 #endif /* DAG_ONLY */
  66
  67 static int dag_setfilter(pcap_t *p, struct bpf_program *fp);
  68 static int dag_stats(pcap_t *p, struct pcap_stat *ps);
  69 static int dag_set_datalink(pcap_t *p, int dlt);
  70
  71 static void delete_pcap_dag(pcap_t *p) {
  72   pcap_dag_node_t *curr = NULL, *prev = NULL;
  73
  74   for (prev = NULL, curr = pcap_dags;
  75       curr != NULL && curr->p != p;
  76       prev = curr, curr = curr->next) {
  77     /* empty */
  78   }
  79
  80   if (curr != NULL && curr->p == p) {
  81     if (prev != NULL) {
  82       prev->next = curr->next;
  83     } else {
  84       pcap_dags = curr->next;
  85     }
  86   }
  87 }
  88
  89 /*
  90  * Performs a graceful shutdown of the DAG card, frees dynamic memory held
  91  * in the pcap_t structure, and closes the file descriptor for the DAG card.
  92  */
  93
  94 static void dag_platform_close(pcap_t *p) {
  95
  96 #ifdef linux
  97   if (p != NULL && p->md.device != NULL) {
  98     if(dag_stop(p->fd) < 0)
  99       fprintf(stderr,"dag_stop %s: %s\n", p->md.device, strerror(errno));
 100     if(dag_close(p->fd) < 0)
 101       fprintf(stderr,"dag_close %s: %s\n", p->md.device, strerror(errno));
 102
 103     free(p->md.device);
 104   }
 105 #else
 106   if (p != NULL) {
 107     if(dag_stop(p->fd) < 0)
 108       fprintf(stderr,"dag_stop: %s\n", strerror(errno));
 109     if(dag_close(p->fd) < 0)
 110       fprintf(stderr,"dag_close: %s\n", strerror(errno));
 111   }
 112 #endif
 113   delete_pcap_dag(p);
 114   /* XXX - does "dag_close()" do this?  If so, we don't need to. */
 115   close(p->fd);
 116 }
 117
 118 static void atexit_handler(void) {
 119   while (pcap_dags != NULL) {
 120     dag_platform_close(pcap_dags->p);
 121   }
 122 }
 123
 124 static int new_pcap_dag(pcap_t *p) {
 125   pcap_dag_node_t *node = NULL;
 126
 127   if ((node = malloc(sizeof(pcap_dag_node_t))) == NULL) {
 128     return -1;
 129   }
 130
 131   if (!atexit_handler_installed) {
 132     atexit(atexit_handler);
 133     atexit_handler_installed = 1;
 134   }
 135
 136   node->next = pcap_dags;
 137   node->p = p;
 138
 139   return 0;
 140 }
 141
 142 /*
 143  * Get pointer to the ERF header for the next packet in the input
 144  * stream. This function blocks until a packet becomes available.
 145  */
 146 static dag_record_t *get_next_dag_header(pcap_t *p) {
 147   register dag_record_t *record;
 148   int rlen;
 149
 150   if (p->md.dag_mem_top - p->md.dag_mem_bottom < dag_record_size) {
 151     p->md.dag_mem_top = dag_offset(p->fd, &(p->md.dag_mem_bottom), 0);
 152   }
 153
 154   record = (dag_record_t *)(p->md.dag_mem_base + p->md.dag_mem_bottom);
 155   rlen = ntohs(record->rlen);
 156   while (p->md.dag_mem_top - p->md.dag_mem_bottom < rlen) {
 157     p->md.dag_mem_top = dag_offset(p->fd, &(p->md.dag_mem_bottom), 0);
 158     record = (dag_record_t *)(p->md.dag_mem_base + p->md.dag_mem_bottom);
 159     rlen = ntohs(record->rlen);
 160   }
 161
 162   p->md.dag_mem_bottom += rlen;
 163
 164   return record;
 165 }
 166
 167 /* Size of payload in ATM packets */
 168 #define ATM_CAPTURE_SIZE 48
 169
 170 /* Size of payload of Ethernet packet */
 171 #define ETHERNET_LENGTH(h) min(ntohs((h)->wlen) - 4, ntohs((h)->rlen) - dag_record_size - 2 - (ntohs((h)->wlen) & 0x3))
 172
 173 /* Size of HDLC packet */
 174 #define HDLC_LENGTH(h) min(ntohs((h)->wlen) - 4, ntohs((h)->rlen) - dag_record_size)
 175
 176 #ifndef min
 177 #define min(a, b) ((a) > (b) ? (b) : (a))
 178 #endif
 179
 180 /*
 181  * Swap byte ordering of unsigned long long on a big endian
 182  * machine.
 183  */
 184 static unsigned long long swapll(unsigned long long ull) {
 185 #if (BYTE_ORDER == BIG_ENDIAN)
 186   return ((ull & 0xff00000000000000LL) >> 56) |
 187     ((ull & 0x00ff000000000000LL) >> 40) |
 188     ((ull & 0x0000ff0000000000LL) >> 24) |
 189     ((ull & 0x000000ff00000000LL) >>  8) |
 190     ((ull & 0x00000000ff000000LL) <<  8) |
 191     ((ull & 0x0000000000ff0000LL) << 24) |
 192     ((ull & 0x000000000000ff00LL) << 40) |
 193     ((ull & 0x00000000000000ffLL) << 56) ;
 194 #else
 195   return ull;
 196 #endif
 197 }
 198
 199 /*
 200  *  Read at most max_packets from the capture stream and call the callback
 201  *  for each of them. Returns the number of packets handled or -1 if an
 202  *  error occured.  A blocking
 203  */
 204 int dag_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user) {
 205   u_char                *dp = NULL;
 206   int                   packet_len = 0, caplen = 0;
 207   struct pcap_pkthdr    pcap_header;
 208
 209   dag_record_t *header;
 210   register unsigned long long ts;
 211
 212   /* Receive a single packet from the kernel */
 213   header = get_next_dag_header(p);
 214   dp = ((u_char *)header) + dag_record_size;
 215
 216   switch(header->type) {
 217   case TYPE_ATM:
 218     packet_len = ATM_CAPTURE_SIZE;
 219     caplen = ATM_CAPTURE_SIZE;
 220     break;
 221   case TYPE_ETH:
 222     packet_len = ntohs(header->wlen);
 223     caplen = ETHERNET_LENGTH(header);
 224     dp += 2;
 225     break;
 226   case TYPE_HDLC_POS:
 227     packet_len = ntohs(header->wlen);
 228     caplen = HDLC_LENGTH(header);
 229     break;
 230   }
 231
 232   if (caplen > p->snapshot)
 233     caplen = p->snapshot;
 234
 235   /* Run the packet filter if not using kernel filter */
 236   if (p->fcode.bf_insns) {
 237     if (bpf_filter(p->fcode.bf_insns, dp, packet_len, caplen) == 0) {
 238       /* rejected by filter */
 239       return 0;
 240     }
 241   }
 242
 243   /* convert between timestamp formats */
 244   ts = swapll(header->ts);
 245   pcap_header.ts.tv_sec  = ts >> 32;
 246   ts = ((ts &  0xffffffffULL) * 1000 * 1000);
 247   ts += (ts & 0x80000000ULL) << 1; /* rounding */
 248   pcap_header.ts.tv_usec = ts >> 32;
 249   if (pcap_header.ts.tv_usec >= 1000000) {
 250     pcap_header.ts.tv_usec -= 1000000;
 251     pcap_header.ts.tv_sec += 1;
 252   }
 253
 254   /* Fill in our own header data */
 255   pcap_header.caplen = caplen;
 256   pcap_header.len = packet_len;
 257
 258   /*
 259    * Count the packet.
 260    */
 261   p->md.stat.ps_recv++;
 262
 263   /* Call the user supplied callback function */
 264   callback(user, &pcap_header, dp);
 265
 266   return 1;
 267 }
 268
 269 /*
 270  *  Get a handle for a live capture from the given DAG device.  Passing a NULL
 271  *  device will result in a failure.  The promisc flag is ignored because DAG
 272  *  cards are always promiscuous.  The to_ms parameter is also ignored as it is
 273  *  not supported in hardware.
 274  *
 275  *  See also pcap(3).
 276  */
 277 pcap_t *dag_open_live(const char *device, int snaplen, int promisc, int to_ms, char *ebuf) {
 278   char conf[30]; /* dag configure string */
 279   pcap_t *handle;
 280
 281   if (device == NULL) {
 282     snprintf(ebuf, PCAP_ERRBUF_SIZE, "device is NULL: %s", pcap_strerror(errno));
 283     return NULL;
 284   }
 285   /* Allocate a handle for this session. */
 286
 287   handle = malloc(sizeof(*handle));
 288   if (handle == NULL) {
 289     snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc %s: %s", device, pcap_strerror(errno));
 290     return NULL;
 291   }
 292
 293   /* Initialize some components of the pcap structure. */
 294
 295   memset(handle, 0, sizeof(*handle));
 296
 297   if (strstr(device, "/dev") == NULL) {
 298     char * newDev = (char *)malloc(strlen(device) + 6);
 299     newDev[0] = '\0';
 300     strcat(newDev, "/dev/");
 301     strcat(newDev,device);
 302     device = newDev;
 303   }
 304
 305   /* setup device parameters */
 306   if((handle->fd = dag_open((char *)device)) < 0) {
 307     snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_open %s: %s", device, pcap_strerror(errno));
 308     return NULL;
 309   }
 310
 311   /* set the card snap length as specified by the specified snaplen parameter */
 312   if (snaplen > MAX_DAG_SNAPLEN) {
 313     snaplen = MAX_DAG_SNAPLEN;
 314   }
 315   snprintf(conf, 30, "varlen slen=%d", (snaplen % 4) ? (snaplen + 3) & ~3 : snaplen); /* snap len has to be a multiple of 4 */
 316   fprintf(stderr, "Configuring DAG with '%s'.\n", conf);
 317   if(dag_configure(handle->fd, conf) < 0) {
 318     snprintf(ebuf, PCAP_ERRBUF_SIZE,"dag_configure %s: %s\n", device, pcap_strerror(errno));
 319     return NULL;
 320   }
 321
 322   if((handle->md.dag_mem_base = dag_mmap(handle->fd)) == MAP_FAILED) {
 323     snprintf(ebuf, PCAP_ERRBUF_SIZE,"dag_mmap %s: %s\n", device, pcap_strerror(errno));
 324     return NULL;
 325   }
 326
 327   if(dag_start(handle->fd) < 0) {
 328     snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_start %s: %s\n", device, pcap_strerror(errno));
 329     return NULL;
 330   }
 331
 332   /*
 333    * Important! You have to ensure bottom is properly
 334    * initialized to zero on startup, it won't give you
 335    * a compiler warning if you make this mistake!
 336    */
 337   handle->md.dag_mem_bottom = 0;
 338   handle->md.dag_mem_top = 0;
 339   handle->md.is_dag = 1;
 340
 341   handle->snapshot      = snaplen;
 342   /*handle->md.timeout  = to_ms; */
 343
 344 #ifdef linux
 345   if (device) {
 346     handle->md.device = strdup(device);
 347   }
 348
 349   if (handle->md.device == NULL) {
 350     snprintf(ebuf, PCAP_ERRBUF_SIZE, "str_dup %s: %s\n", device, pcap_strerror(errno));
 351     free(handle);
 352     return NULL;
 353   }
 354 #endif
 355
 356   /* set link type */
 357
 358   /* Check the type through a dagapi call.
 359   */
 360   switch(dag_linktype(handle->fd)) {
 361   case TYPE_HDLC_POS:
 362     handle->linktype = DLT_CHDLC;
 363     fprintf(stderr, "Set DAG linktype to %d (DLT_CHDLC)\n", handle->linktype);
 364     break;
 365   case TYPE_ETH:
 366     handle->linktype = DLT_EN10MB;
 367     fprintf(stderr, "Set DAG linktype to %d (DLT_EN10MB)\n", handle->linktype);
 368     break;
 369   case TYPE_ATM:
 370     handle->linktype = DLT_ATM_RFC1483;
 371     fprintf(stderr, "Set DAG linktype to %d (DLT_ATM_RFC1483)\n", handle->linktype);
 372     break;
 373   case TYPE_LEGACY:
 374     handle->linktype = DLT_NULL;
 375     fprintf(stderr, "Set DAG linktype to %d (DLT_NULL)\n", handle->linktype);
 376     break;
 377   default:
 378     snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_open_live %s: unknown linktype %d\n", device, dag_linktype(handle->fd));
 379     return NULL;
 380   }
 381
 382   handle->bufsize = 0;/*handle->snapshot;*/
 383
 384   if (new_pcap_dag(handle) < 0) {
 385     snprintf(ebuf, PCAP_ERRBUF_SIZE, "new_pcap_dag %s: %s\n", device, pcap_strerror(errno));
 386     return NULL;
 387   }
 388
 389   handle->setfilter_op = dag_setfilter;
 390   handle->set_datalink_op = dag_set_datalink;
 391   handle->stats_op = dag_stats;
 392   handle->close_op = dag_platform_close;
 393
 394   return handle;
 395 }
 396
 397 static int dag_stats(pcap_t *p, struct pcap_stat *ps) {
 398   /* This needs to be filled out correctly.  Hopefully a dagapi call will
 399      provide all necessary information.
 400   */
 401   /*p->md.stat.ps_recv = 0;*/
 402   /*p->md.stat.ps_drop = 0;*/
 403
 404   *ps = p->md.stat;
 405
 406   return 0;
 407 }
 408
 409 /*
 410  * Get from "/proc/dag" all interfaces listed there; if they're
 411  * already in the list of interfaces we have, that won't add another
 412  * instance, but if they're not, that'll add them.
 413  *
 414  * We don't bother getting any addresses for them.
 415  *
 416  * We also don't fail if we couldn't open "/proc/dag"; we just leave
 417  * the list of interfaces as is.
 418  */
 419 int
 420 dag_platform_finddevs(pcap_if_t **devlistp, char *errbuf)
 421 {
 422   FILE *proc_dag_f;
 423   char linebuf[512];
 424   int linenum;
 425   unsigned char *p;
 426   char name[512];       /* XXX - pick a size */
 427   char *q, *saveq;
 428   struct ifreq ifrflags;
 429   int ret = 0;
 430
 431   /* Quick exit if /proc/dag not readable */
 432   proc_dag_f = fopen("/proc/dag", "r");
 433   if (proc_dag_f == NULL)
 434   {
 435     int i, fd;
 436     char dev[16] = "dagx";
 437
 438     for (i = '0'; ret == 0 && i <= '9'; i++) {
 439       dev[3] = i;
 440       if (pcap_add_if(devlistp, dev, 0, NULL, errbuf) == -1) {
 441         /*
 442          * Failure.
 443          */
 444         ret = -1;
 445       }
 446     }
 447
 448     return (ret);
 449   }
 450
 451   for (linenum = 1;
 452         fgets(linebuf, sizeof linebuf, proc_dag_f) != NULL; linenum++) {
 453
 454     /*
 455      * Skip the first two lines - they're headers.
 456      */
 457     if (linenum <= 2)
 458       continue;
 459
 460     p = &linebuf[0];
 461
 462     if (*p == '\0' || *p == '\n' || *p != 'D')
 463       continue;  /* not a Dag line */
 464
 465     /*
 466      * Get the interface name.
 467      */
 468     q = &name[0];
 469     while (*p != '\0' && *p != ':') {
 470       if (*p != ' ')
 471         *q++ = tolower(*p++);
 472       else
 473         p++;
 474     }
 475     *q = '\0';
 476
 477     /*
 478      * Add an entry for this interface, with no addresses.
 479      */
 480     p[strlen(p) - 1] = '\0'; /* get rid of \n */
 481     if (pcap_add_if(devlistp, name, 0, strdup(p + 2), errbuf) == -1) {
 482       /*
 483        * Failure.
 484        */
 485       ret = -1;
 486       break;
 487     }
 488   }
 489   if (ret != -1) {
 490     /*
 491      * Well, we didn't fail for any other reason; did we
 492      * fail due to an error reading the file?
 493      */
 494     if (ferror(proc_dag_f)) {
 495       (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 496           "Error reading /proc/dag: %s",
 497           pcap_strerror(errno));
 498       ret = -1;
 499     }
 500   }
 501
 502   (void)fclose(proc_dag_f);
 503   return (ret);
 504 }
 505
 506 /*
 507  * Installs the gven bpf filter program in the given pcap structure.  There is
 508  * no attempt to store the filter in kernel memory as that is not supported
 509  * with DAG cards.
 510  */
 511 static int dag_setfilter(pcap_t *p, struct bpf_program *fp) {
 512   if (!p)
 513     return -1;
 514   if (!fp) {
 515     strncpy(p->errbuf, "setfilter: No filter specified",
 516             sizeof(p->errbuf));
 517     return -1;
 518   }
 519
 520   /* Make our private copy of the filter */
 521
 522   if (install_bpf_program(p, fp) < 0) {
 523     snprintf(p->errbuf, sizeof(p->errbuf),
 524              "malloc: %s", pcap_strerror(errno));
 525     return -1;
 526   }
 527
 528   p->md.use_bpf = 0;
 529
 530   return (0);
 531 }
 532
 533 static int
 534 dag_set_datalink(pcap_t *p, int dlt)
 535 {
 536         return (0);
 537 }