pcap-dag.c

Ubuntu packages of security software。 相当不错的源码

/*
 * 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  <[e-mail]>
 *                Koryn Grant      <[e-mail]>
 *                Stephen Donnelly <[e-mail]>
 */

#ifndef lint
static const char rcsid[] _U_ =
	"@(#) $Header: /tcpdump/master/libpcap/pcap-dag.c,v 1.21.2.3 2005/07/10 22:09:34 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_CELL_SIZE		52
#define ATM_HDR_SIZE		4

/* 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))

/*
 * 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)
{
	
	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(dag_close(p->fd) < 0)
			fprintf(stderr,"dag_close: %s\n", strerror(errno));
#ifdef linux		
		free(p->md.device);
#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;

	/* 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.
		 */
		p->md.dag_mem_top = dag_advance_stream(p->fd, p->md.dag_stream, (void**)&(p->md.dag_mem_bottom));
#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;

		switch(header->type) {
		case TYPE_AAL5:
		case TYPE_ATM:
#ifdef TYPE_MC_ATM
		case TYPE_MC_ATM:
			if (header->type == TYPE_MC_ATM) {
				caplen = packet_len = ATM_CELL_SIZE;
				dp+=4;
			}
#endif
#ifdef TYPE_MC_AAL5
		case TYPE_MC_AAL5:
			if (header->type == TYPE_MC_AAL5) {
				packet_len = ntohs(header->wlen);
				caplen = rlen - dag_record_size - 4;
				dp+=4;
			}
#endif
			if (header->type == TYPE_AAL5) {
				packet_len = ntohs(header->wlen);
				caplen = rlen - dag_record_size;
			} else 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;

#ifdef TYPE_COLOR_ETH
		case TYPE_COLOR_ETH:
#endif
		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;
#ifdef TYPE_COLOR_HDLC_POS
		case TYPE_COLOR_HDLC_POS:
#endif
		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;
#ifdef TYPE_MC_HDLC
		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;
			}
			dp += 4;
			break;
#endif
		}
 
		if (caplen > p->snapshot)
			caplen = p->snapshot;

		/* Count lost packets. */
		switch(header->type) {
#ifdef TYPE_COLOR_HDLC_POS
			/* in this type the color value overwrites the lctr */
		case TYPE_COLOR_HDLC_POS:
			break;
#endif
#ifdef TYPE_COLOR_ETH
			/* in this type the color value overwrites the lctr */
		case TYPE_COLOR_ETH:
			break;
#endif
		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);
				}
			}
		}

		/* 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;
			}
		}
	}

	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