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libpcap/pcap-dag.c

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/*
* 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
* 2003 September - Koryn Grant <koryn@endace.com>
* Added support for nonblocking operation.
* Added support for processing more than a single packet in pcap_dispatch().
* Fixed bug in loss counter code.
* Improved portability of loss counter code (e.g. use UINT_MAX instead of 0xffff).
* Removed unused local variables.
* Added required headers (ctype.h, limits.h, unistd.h, netinet/in.h).
* 2003 October - Koryn Grant <koryn@endace.com.>
* Changed semantics to match those of standard pcap on linux.
* - packets rejected by the filter are not counted.
*/
#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header: /tcpdump/master/libpcap/pcap-dag.c,v 1.14 2003-11-21 10:19:33 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>
#define MIN_DAG_SNAPLEN 12
#define MAX_DAG_SNAPLEN 2040
#define ATM_SNAPLEN 48
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))
/*
* Swap byte ordering of unsigned long long timestamp on a big endian
* machine.
*/
#define SWAP_TS(ull) ((ull & 0xff00000000000000LL) >> 56) | \
((ull & 0x00ff000000000000LL) >> 40) | \
((ull & 0x0000ff0000000000LL) >> 24) | \
((ull & 0x000000ff00000000LL) >> 8) | \
((ull & 0x00000000ff000000LL) << 8) | \
((ull & 0x0000000000ff0000LL) << 24) | \
((ull & 0x000000000000ff00LL) << 40) | \
((ull & 0x00000000000000ffLL) << 56)
#ifdef DAG_ONLY
/* This code is required when compiling for a DAG device only. */
#include "pcap-dag.h"
/* Replace dag function names with pcap equivalent. */
#define dag_open_live pcap_open_live
#define dag_platform_finddevs pcap_platform_finddevs
#endif /* DAG_ONLY */
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_close(pcap_t *p) {
#ifdef linux
if (p != NULL && 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) {
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);
/* 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_close(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;
}
/*
* 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;
for (;;)
{
/* 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;
}
p->md.dag_mem_top = dag_offset(p->fd, &(p->md.dag_mem_bottom), flags);
if ((p->md.dag_mem_top - p->md.dag_mem_bottom < dag_record_size) && nonblocking)
{
/* Pcap is configured to process only available packets, and there aren't any. */
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;
dag_record_t *header = (dag_record_t *)(p->md.dag_mem_base + p->md.dag_mem_bottom);
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;
}
if (IS_BIGENDIAN())
{
rlen = header->rlen;
}
else
{
rlen = ntohs(header->rlen);
}
p->md.dag_mem_bottom += rlen;
switch(header->type) {
case TYPE_ATM:
packet_len = ATM_SNAPLEN;
caplen = ATM_SNAPLEN;
dp += 4;
break;
case TYPE_ETH:
if (IS_BIGENDIAN())
{
packet_len = header->wlen;
}
else
{
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_HDLC_POS:
if (IS_BIGENDIAN())
{
packet_len = header->wlen;
}
else
{
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;
}
if (caplen > p->snapshot)
caplen = p->snapshot;
/* Count lost packets. */
if (header->lctr) {
if (p->md.stat.ps_drop > (UINT_MAX - header->lctr)) {
p->md.stat.ps_drop = UINT_MAX;
} else {
p->md.stat.ps_drop += header->lctr;
}
}
/* 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 = SWAP_TS(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)
{
/* Reached the user-specified limit. */
return cnt;
}
}
}
if (nonblocking || processed)
{
return processed;
}
}
return processed;
}
/*
* 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 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;
char *s;
int n;
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;
} else {
device = strdup(device);
}
if (device == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "str_dup: %s\n", pcap_strerror(errno));
goto fail;
}
/* setup device parameters */
if((handle->fd = dag_open((char *)device)) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_open %s: %s", device, pcap_strerror(errno));
goto fail;
}
/* set the card snap length to the specified snaplen parameter */
if (snaplen == 0 || snaplen > MAX_DAG_SNAPLEN) {
snaplen = MAX_DAG_SNAPLEN;
} else if (snaplen < MIN_DAG_SNAPLEN) {
snaplen = MIN_DAG_SNAPLEN;
}
/* snap len has to be a multiple of 4 */
snprintf(conf, 30, "varlen slen=%d", (snaplen + 3) & ~3);
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));
goto fail;
}
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));
goto fail;
}
if(dag_start(handle->fd) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_start %s: %s\n", device, pcap_strerror(errno));
goto fail;
}
/*
* 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;
/* TODO: query the card */
handle->md.dag_fcs_bits = 32;
if ((s = getenv("ERF_FCS_BITS")) != NULL) {
if ((n = atoi(s)) == 0 || n == 16|| n == 32) {
handle->md.dag_fcs_bits = n;
} else {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"pcap_open_live %s: bad ERF_FCS_BITS value (%d) in environment\n", device, n);
goto fail;
}
}
handle->snapshot = snaplen;
/*handle->md.timeout = to_ms; */
if ((handle->linktype = dag_get_datalink(handle)) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "dag_get_linktype %s: unknown linktype\n", device);
goto fail;
}
handle->bufsize = 0;
if (new_pcap_dag(handle) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "new_pcap_dag %s: %s\n", device, pcap_strerror(errno));
goto fail;
}
/*
* "select()" and "poll()" don't (yet) work on DAG device descriptors.
*/
handle->selectable_fd = -1;
#ifdef linux
handle->md.device = (char *)device;
#else
free((char *)device);
device = NULL;
#endif
handle->read_op = dag_read;
handle->setfilter_op = dag_setfilter;
handle->set_datalink_op = dag_set_datalink;
handle->getnonblock_op = pcap_getnonblock_fd;
handle->setnonblock_op = dag_setnonblock;
handle->stats_op = dag_stats;
handle->close_op = dag_platform_close;
return handle;
fail:
if (device != NULL) {
free((char *)device);
}
if (handle != NULL) {
free(handle);
}
return NULL;
}
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;
}
/*
* 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;
int ret = 0;
/* Quick exit if /proc/dag not readable */
proc_dag_f = fopen("/proc/dag", "r");
if (proc_dag_f == NULL)
{
int i;
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 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) {
snprintf(p->errbuf, sizeof(p->errbuf),
"malloc: %s", pcap_strerror(errno));
return -1;
}
p->md.use_bpf = 0;
return (0);
}
static int
dag_set_datalink(pcap_t *p, int 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);
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 linktype = -1;
/* Check the type through a dagapi call.
*/
switch(dag_linktype(p->fd)) {
case TYPE_HDLC_POS: {
dag_record_t *record;
/* peek at the first available record to see if it is PPP */
while ((p->md.dag_mem_top - p->md.dag_mem_bottom) < (dag_record_size + 4)) {
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);
if ((ntohl(record->rec.pos.hdlc) & 0xffff0000) == 0xff030000) {
linktype = DLT_PPP_SERIAL;
fprintf(stderr, "Set DAG linktype to %d (DLT_PPP_SERIAL)\n", linktype);
} else {
linktype = DLT_CHDLC;
fprintf(stderr, "Set DAG linktype to %d (DLT_CHDLC)\n", linktype);
}
break;
}
case TYPE_ETH:
linktype = DLT_EN10MB;
fprintf(stderr, "Set DAG linktype to %d (DLT_EN10MB)\n", linktype);
break;
case TYPE_ATM:
linktype = DLT_ATM_RFC1483;
fprintf(stderr, "Set DAG linktype to %d (DLT_ATM_RFC1483)\n", linktype);
break;
case TYPE_LEGACY:
linktype = DLT_NULL;
fprintf(stderr, "Set DAG linktype to %d (DLT_NULL)\n", linktype);
break;
default:
fprintf(stderr, "Unknown DAG linktype %d\n", dag_linktype(p->fd));
break;
}
return linktype;
}
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