Merge pull request #1 from the-tcpdump-group/master

[libpcap] / pcap-win32.c

/*
 * Copyright (c) 1999 - 2005 NetGroup, Politecnico di Torino (Italy)
 * Copyright (c) 2005 - 2010 CACE Technologies, Davis (California)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Politecnico di Torino, CACE Technologies
 * nor the names of its contributors may be used to endorse or promote
 * products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#define PCAP_DONT_INCLUDE_PCAP_BPF_H
#include <Packet32.h>
#include <pcap-int.h>
#include <pcap/dlt.h>
#ifdef __MINGW32__
#ifdef __MINGW64__
#include <ntddndis.h>
#else  /*__MINGW64__*/
#include <ddk/ntddndis.h>
#include <ddk/ndis.h>
#endif /*__MINGW64__*/
#else /*__MINGW32__*/
#include <ntddndis.h>
#endif /*__MINGW32__*/
#ifdef HAVE_DAG_API
#include <dagnew.h>
#include <dagapi.h>
#endif /* HAVE_DAG_API */
#ifdef __MINGW32__
int* _errno();
#define errno (*_errno())
#endif /* __MINGW32__ */

static int pcap_setfilter_win32_npf(pcap_t *, struct bpf_program *);
static int pcap_setfilter_win32_dag(pcap_t *, struct bpf_program *);
static int pcap_getnonblock_win32(pcap_t *);
static int pcap_setnonblock_win32(pcap_t *, int);

/*dimension of the buffer in the pcap_t structure*/
#define WIN32_DEFAULT_USER_BUFFER_SIZE 256000

/*dimension of the buffer in the kernel driver NPF */
#define WIN32_DEFAULT_KERNEL_BUFFER_SIZE 1000000

/* Equivalent to ntohs(), but a lot faster under Windows */
#define SWAPS(_X) ((_X & 0xff) << 8) | (_X >> 8)

/*
 * Private data for capturing on WinPcap devices.
 */
struct pcap_win {
        int nonblock;
        int rfmon_selfstart;            /* a flag tells whether the monitor mode is set by itself */
        int filtering_in_kernel;        /* using kernel filter */

#ifdef HAVE_DAG_API
        int     dag_fcs_bits;           /* Number of checksum bits from link layer */
#endif

#ifdef HAVE_REMOTE
        int samp_npkt;                  /* parameter needed for sampling, with '1 out of N' method has been requested */
        struct timeval samp_time;       /* parameter needed for sampling, with '1 every N ms' method has been requested */
#endif
};

BOOL WINAPI DllMain(
  HANDLE hinstDLL,
  DWORD dwReason,
  LPVOID lpvReserved
)
{
        return (TRUE);
}

/*
 * Define stub versions of the monitor-mode support routines if this
 * isn't Npcap. HAVE_NPCAP_PACKET_API is defined by Npcap but not
 * WinPcap.
 */
#ifndef HAVE_NPCAP_PACKET_API
static int
PacketIsMonitorModeSupported(PCHAR AdapterName _U_)
{
        /*
         * We don't support monitor mode.
         */
        return (0);
}

static int
PacketSetMonitorMode(PCHAR AdapterName _U_, int mode _U_)
{
        /*
         * This should never be called, as PacketIsMonitorModeSupported()
         * will return 0, meaning "we don't support monitor mode, so
         * don't try to turn it on or off".
         */
        return (0);
}

static int
PacketGetMonitorMode(PCHAR AdapterName _U_)
{
        /*
         * This should fail, so that pcap_activate_win32() returns
         * PCAP_ERROR_RFMON_NOTSUP if our caller requested monitor
         * mode.
         */
        return (-1);
}
#endif

/* Start winsock */
int
wsockinit(void)
{
        WORD wVersionRequested;
        WSADATA wsaData;
        static int err = -1;
        static int done = 0;

        if (done)
                return (err);

        wVersionRequested = MAKEWORD( 1, 1);
        err = WSAStartup( wVersionRequested, &wsaData );
        atexit ((void(*)(void))WSACleanup);
        done = 1;

        if ( err != 0 )
                err = -1;
        return (err);
}

int
pcap_wsockinit(void)
{
       return (wsockinit());
}

static int
pcap_stats_win32(pcap_t *p, struct pcap_stat *ps)
{
        struct bpf_stat bstats;
        char errbuf[PCAP_ERRBUF_SIZE+1];

        /*
         * Try to get statistics.
         *
         * (Please note - "struct pcap_stat" is *not* the same as
         * WinPcap's "struct bpf_stat". It might currently have the
         * same layout, but let's not cheat.
         *
         * Note also that we don't fill in ps_capt, as we might have
         * been called by code compiled against an earlier version of
         * WinPcap that didn't have ps_capt, in which case filling it
         * in would stomp on whatever comes after the structure passed
         * to us.
         */
        if (!PacketGetStats(p->adapter, &bstats)) {
                pcap_win32_err_to_str(GetLastError(), errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "PacketGetStats error: %s", errbuf);
                return (-1);
        }
        ps->ps_recv = bstats.bs_recv;
        ps->ps_drop = bstats.bs_drop;

        /*
         * XXX - PacketGetStats() doesn't fill this in, so we just
         * return 0.
         */
#if 0
        ps->ps_ifdrop = bstats.ps_ifdrop;
#else
        ps->ps_ifdrop = 0;
#endif

        return (0);
}

/*
 * Win32-only routine for getting statistics.
 *
 * This way is definitely safer than passing the pcap_stat * from the userland.
 * In fact, there could happen than the user allocates a variable which is not
 * big enough for the new structure, and the library will write in a zone
 * which is not allocated to this variable.
 *
 * In this way, we're pretty sure we are writing on memory allocated to this
 * variable.
 *
 * XXX - but this is the wrong way to handle statistics.  Instead, we should
 * have an API that returns data in a form like the Options section of a
 * pcapng Interface Statistics Block:
 *
 *    http://xml2rfc.tools.ietf.org/cgi-bin/xml2rfc.cgi?url=https://raw.githubusercontent.com/pcapng/pcapng/master/draft-tuexen-opsawg-pcapng.xml&modeAsFormat=html/ascii&type=ascii#rfc.section.4.6
 *
 * which would let us add new statistics straightforwardly and indicate which
 * statistics we are and are *not* providing, rather than having to provide
 * possibly-bogus values for statistics we can't provide.
 */
struct pcap_stat *
pcap_stats_ex_win32(pcap_t *p, int *pcap_stat_size)
{
        struct bpf_stat bstats;
        char errbuf[PCAP_ERRBUF_SIZE+1];

        *pcap_stat_size = sizeof (p->stat);

        /*
         * Try to get statistics.
         *
         * (Please note - "struct pcap_stat" is *not* the same as
         * WinPcap's "struct bpf_stat". It might currently have the
         * same layout, but let's not cheat.)
         */
        if (!PacketGetStatsEx(p->adapter, &bstats)) {
                pcap_win32_err_to_str(GetLastError(), errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "PacketGetStatsEx error: %s", errbuf);
                return (NULL);
        }
        p->stat.ps_recv = bstats.bs_recv;
        p->stat.ps_drop = bstats.bs_drop;
        p->stat.ps_ifdrop = bstats.ps_ifdrop;
#ifdef HAVE_REMOTE
        p->stat.ps_capt = bstats.bs_capt;
#endif
        return (&p->stat);
}

/* Set the dimension of the kernel-level capture buffer */
static int
pcap_setbuff_win32(pcap_t *p, int dim)
{
        if(PacketSetBuff(p->adapter,dim)==FALSE)
        {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: not enough memory to allocate the kernel buffer");
                return (-1);
        }
        return (0);
}

/* Set the driver working mode */
static int
pcap_setmode_win32(pcap_t *p, int mode)
{
        if(PacketSetMode(p->adapter,mode)==FALSE)
        {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: working mode not recognized");
                return (-1);
        }

        return (0);
}

/*set the minimum amount of data that will release a read call*/
static int
pcap_setmintocopy_win32(pcap_t *p, int size)
{
        if(PacketSetMinToCopy(p->adapter, size)==FALSE)
        {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: unable to set the requested mintocopy size");
                return (-1);
        }
        return (0);
}

static HANDLE
pcap_getevent_win32(pcap_t *p)
{
        return (PacketGetReadEvent(p->adapter));
}

static int
pcap_oid_get_request_win32(pcap_t *p, bpf_u_int32 oid, void *data, size_t *lenp)
{
        PACKET_OID_DATA *oid_data_arg;
        char errbuf[PCAP_ERRBUF_SIZE+1];

        /*
         * Allocate a PACKET_OID_DATA structure to hand to PacketRequest().
         * It should be big enough to hold "*lenp" bytes of data; it
         * will actually be slightly larger, as PACKET_OID_DATA has a
         * 1-byte data array at the end, standing in for the variable-length
         * data that's actually there.
         */
        oid_data_arg = malloc(sizeof (PACKET_OID_DATA) + *lenp);
        if (oid_data_arg == NULL) {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Couldn't allocate argument buffer for PacketRequest");
                return (PCAP_ERROR);
        }

        /*
         * No need to copy the data - we're doing a fetch.
         */
        oid_data_arg->Oid = oid;
        oid_data_arg->Length = (ULONG)(*lenp);  /* XXX - check for ridiculously large value? */
        if (!PacketRequest(p->adapter, FALSE, oid_data_arg)) {
                pcap_win32_err_to_str(GetLastError(), errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error calling PacketRequest: %s", errbuf);
                free(oid_data_arg);
                return (PCAP_ERROR);
        }

        /*
         * Get the length actually supplied.
         */
        *lenp = oid_data_arg->Length;

        /*
         * Copy back the data we fetched.
         */
        memcpy(data, oid_data_arg->Data, *lenp);
        free(oid_data_arg);
        return (0);
}

static int
pcap_oid_set_request_win32(pcap_t *p, bpf_u_int32 oid, const void *data,
    size_t *lenp)
{
        PACKET_OID_DATA *oid_data_arg;
        char errbuf[PCAP_ERRBUF_SIZE+1];

        /*
         * Allocate a PACKET_OID_DATA structure to hand to PacketRequest().
         * It should be big enough to hold "*lenp" bytes of data; it
         * will actually be slightly larger, as PACKET_OID_DATA has a
         * 1-byte data array at the end, standing in for the variable-length
         * data that's actually there.
         */
        oid_data_arg = malloc(sizeof (PACKET_OID_DATA) + *lenp);
        if (oid_data_arg == NULL) {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Couldn't allocate argument buffer for PacketRequest");
                return (PCAP_ERROR);
        }

        oid_data_arg->Oid = oid;
        oid_data_arg->Length = (ULONG)(*lenp);  /* XXX - check for ridiculously large value? */
        memcpy(oid_data_arg->Data, data, *lenp);
        if (!PacketRequest(p->adapter, TRUE, oid_data_arg)) {
                pcap_win32_err_to_str(GetLastError(), errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error calling PacketRequest: %s", errbuf);
                free(oid_data_arg);
                return (PCAP_ERROR);
        }

        /*
         * Get the length actually copied.
         */
        *lenp = oid_data_arg->Length;

        /*
         * No need to copy the data - we're doing a set.
         */
        free(oid_data_arg);
        return (0);
}

static u_int
pcap_sendqueue_transmit_win32(pcap_t *p, pcap_send_queue *queue, int sync)
{
        u_int res;
        char errbuf[PCAP_ERRBUF_SIZE+1];

        if (p->adapter==NULL) {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Cannot transmit a queue to an offline capture or to a TurboCap port");
                return (0);
        }

        res = PacketSendPackets(p->adapter,
                queue->buffer,
                queue->len,
                (BOOLEAN)sync);

        if(res != queue->len){
                pcap_win32_err_to_str(GetLastError(), errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error opening adapter: %s", errbuf);
        }

        return (res);
}

static int
pcap_setuserbuffer_win32(pcap_t *p, int size)
{
        unsigned char *new_buff;

        if (size<=0) {
                /* Bogus parameter */
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error: invalid size %d",size);
                return (-1);
        }

        /* Allocate the buffer */
        new_buff=(unsigned char*)malloc(sizeof(char)*size);

        if (!new_buff) {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error: not enough memory");
                return (-1);
        }

        free(p->buffer);

        p->buffer=new_buff;
        p->bufsize=size;

        return (0);
}

static int
pcap_live_dump_win32(pcap_t *p, char *filename, int maxsize, int maxpacks)
{
        BOOLEAN res;

        /* Set the packet driver in dump mode */
        res = PacketSetMode(p->adapter, PACKET_MODE_DUMP);
        if(res == FALSE){
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error setting dump mode");
                return (-1);
        }

        /* Set the name of the dump file */
        res = PacketSetDumpName(p->adapter, filename, (int)strlen(filename));
        if(res == FALSE){
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error setting kernel dump file name");
                return (-1);
        }

        /* Set the limits of the dump file */
        res = PacketSetDumpLimits(p->adapter, maxsize, maxpacks);

        return (0);
}

static int
pcap_live_dump_ended_win32(pcap_t *p, int sync)
{
        return (PacketIsDumpEnded(p->adapter, (BOOLEAN)sync));
}

static PAirpcapHandle
pcap_get_airpcap_handle_win32(pcap_t *p)
{
#ifdef HAVE_AIRPCAP_API
        return (PacketGetAirPcapHandle(p->adapter));
#else
        return (NULL);
#endif /* HAVE_AIRPCAP_API */
}

static int
pcap_read_win32_npf(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
        PACKET Packet;
        int cc;
        int n = 0;
        register u_char *bp, *ep;
        u_char *datap;
        struct pcap_win *pw = p->priv;

        cc = p->cc;
        if (p->cc == 0) {
                /*
                 * Has "pcap_breakloop()" been called?
                 */
                if (p->break_loop) {
                        /*
                         * Yes - clear the flag that indicates that it
                         * has, and return PCAP_ERROR_BREAK to indicate
                         * that we were told to break out of the loop.
                         */
                        p->break_loop = 0;
                        return (PCAP_ERROR_BREAK);
                }

                /*
                 * Capture the packets.
                 *
                 * The PACKET structure had a bunch of extra stuff for
                 * Windows 9x/Me, but the only interesting data in it
                 * in the versions of Windows that we support is just
                 * a copy of p->buffer, a copy of p->buflen, and the
                 * actual number of bytes read returned from
                 * PacketReceivePacket(), none of which has to be
                 * retained from call to call, so we just keep one on
                 * the stack.
                 */
                PacketInitPacket(&Packet, (BYTE *)p->buffer, p->bufsize);
                if (!PacketReceivePacket(p->adapter, &Packet, TRUE)) {
                        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read error: PacketReceivePacket failed");
                        return (PCAP_ERROR);
                }

                cc = Packet.ulBytesReceived;

                bp = p->buffer;
        }
        else
                bp = p->bp;

        /*
         * Loop through each packet.
         */
#define bhp ((struct bpf_hdr *)bp)
        ep = bp + cc;
        while (1) {
                register int caplen, hdrlen;

                /*
                 * Has "pcap_breakloop()" been called?
                 * If so, return immediately - if we haven't read any
                 * packets, clear the flag and return PCAP_ERROR_BREAK
                 * to indicate that we were told to break out of the loop,
                 * otherwise leave the flag set, so that the *next* call
                 * will break out of the loop without having read any
                 * packets, and return the number of packets we've
                 * processed so far.
                 */
                if (p->break_loop) {
                        if (n == 0) {
                                p->break_loop = 0;
                                return (PCAP_ERROR_BREAK);
                        } else {
                                p->bp = bp;
                                p->cc = (int) (ep - bp);
                                return (n);
                        }
                }
                if (bp >= ep)
                        break;

                caplen = bhp->bh_caplen;
                hdrlen = bhp->bh_hdrlen;
                datap = bp + hdrlen;

                /*
                 * Short-circuit evaluation: if using BPF filter
                 * in kernel, no need to do it now - we already know
                 * the packet passed the filter.
                 *
                 * XXX - bpf_filter() should always return TRUE if
                 * handed a null pointer for the program, but it might
                 * just try to "run" the filter, so we check here.
                 */
                if (pw->filtering_in_kernel ||
                    p->fcode.bf_insns == NULL ||
                    bpf_filter(p->fcode.bf_insns, datap, bhp->bh_datalen, caplen)) {
#ifdef HAVE_REMOTE
                        switch (p->rmt_samp.method) {

                        case PCAP_SAMP_1_EVERY_N:
                                pw->samp_npkt = (pw->samp_npkt + 1) % p->rmt_samp.value;

                                /* Discard all packets that are not '1 out of N' */
                                if (pw->samp_npkt != 0) {
                                        bp += Packet_WORDALIGN(caplen + hdrlen);
                                        continue;
                                }
                                break;

                        case PCAP_SAMP_FIRST_AFTER_N_MS:
                            {
                                struct pcap_pkthdr *pkt_header = (struct pcap_pkthdr*) bp;

                                /*
                                 * Check if the timestamp of the arrived
                                 * packet is smaller than our target time.
                                 */
                                if (pkt_header->ts.tv_sec < pw->samp_time.tv_sec ||
                                   (pkt_header->ts.tv_sec == pw->samp_time.tv_sec && pkt_header->ts.tv_usec < pw->samp_time.tv_usec)) {
                                        bp += Packet_WORDALIGN(caplen + hdrlen);
                                        continue;
                                }

                                /*
                                 * The arrived packet is suitable for being
                                 * delivered to our caller, so let's update
                                 * the target time.
                                 */
                                pw->samp_time.tv_usec = pkt_header->ts.tv_usec + p->rmt_samp.value * 1000;
                                if (pw->samp_time.tv_usec > 1000000) {
                                        pw->samp_time.tv_sec = pkt_header->ts.tv_sec + pw->samp_time.tv_usec / 1000000;
                                        pw->samp_time.tv_usec = pw->samp_time.tv_usec % 1000000;
                                }
                            }
                        }
#endif  /* HAVE_REMOTE */

                        /*
                         * XXX A bpf_hdr matches a pcap_pkthdr.
                         */
                        (*callback)(user, (struct pcap_pkthdr*)bp, datap);
                        bp += Packet_WORDALIGN(caplen + hdrlen);
                        if (++n >= cnt && !PACKET_COUNT_IS_UNLIMITED(cnt)) {
                                p->bp = bp;
                                p->cc = (int) (ep - bp);
                                return (n);
                        }
                } else {
                        /*
                         * Skip this packet.
                         */
                        bp += Packet_WORDALIGN(caplen + hdrlen);
                }
        }
#undef bhp
        p->cc = 0;
        return (n);
}

#ifdef HAVE_DAG_API
static int
pcap_read_win32_dag(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
        struct pcap_win *pw = p->priv;
        PACKET Packet;
        u_char *dp = NULL;
        int     packet_len = 0, caplen = 0;
        struct pcap_pkthdr      pcap_header;
        u_char *endofbuf;
        int n = 0;
        dag_record_t *header;
        unsigned erf_record_len;
        ULONGLONG ts;
        int cc;
        unsigned swt;
        unsigned dfp = p->adapter->DagFastProcess;

        cc = p->cc;
        if (cc == 0) /* Get new packets only if we have processed all the ones of the previous read */
        {
                /*
                 * Get new packets from the network.
                 *
                 * The PACKET structure had a bunch of extra stuff for
                 * Windows 9x/Me, but the only interesting data in it
                 * in the versions of Windows that we support is just
                 * a copy of p->buffer, a copy of p->buflen, and the
                 * actual number of bytes read returned from
                 * PacketReceivePacket(), none of which has to be
                 * retained from call to call, so we just keep one on
                 * the stack.
                 */
                PacketInitPacket(&Packet, (BYTE *)p->buffer, p->bufsize);
                if (!PacketReceivePacket(p->adapter, &Packet, TRUE)) {
                        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read error: PacketReceivePacket failed");
                        return (-1);
                }

                cc = Packet.ulBytesReceived;
                if(cc == 0)
                        /* The timeout has expired but we no packets arrived */
                        return (0);
                header = (dag_record_t*)p->adapter->DagBuffer;
        }
        else
                header = (dag_record_t*)p->bp;

        endofbuf = (char*)header + cc;

        /*
         * Cycle through the packets
         */
        do
        {
                erf_record_len = SWAPS(header->rlen);
                if((char*)header + erf_record_len > endofbuf)
                        break;

                /* Increase the number of captured packets */
                p->stat.ps_recv++;

                /* Find the beginning of the packet */
                dp = ((u_char *)header) + dag_record_size;

                /* Determine actual packet len */
                switch(header->type)
                {
                case TYPE_ATM:
                        packet_len = ATM_SNAPLEN;
                        caplen = ATM_SNAPLEN;
                        dp += 4;

                        break;

                case TYPE_ETH:
                        swt = SWAPS(header->wlen);
                        packet_len = swt - (pw->dag_fcs_bits);
                        caplen = erf_record_len - dag_record_size - 2;
                        if (caplen > packet_len)
                        {
                                caplen = packet_len;
                        }
                        dp += 2;

                        break;

                case TYPE_HDLC_POS:
                        swt = SWAPS(header->wlen);
                        packet_len = swt - (pw->dag_fcs_bits);
                        caplen = erf_record_len - dag_record_size;
                        if (caplen > packet_len)
                        {
                                caplen = packet_len;
                        }

                        break;
                }

                if(caplen > p->snapshot)
                        caplen = p->snapshot;

                /*
                 * Has "pcap_breakloop()" been called?
                 * If so, return immediately - if we haven't read any
                 * packets, clear the flag and return -2 to indicate
                 * that we were told to break out of the loop, otherwise
                 * leave the flag set, so that the *next* call will break
                 * out of the loop without having read any packets, and
                 * return the number of packets we've processed so far.
                 */
                if (p->break_loop)
                {
                        if (n == 0)
                        {
                                p->break_loop = 0;
                                return (-2);
                        }
                        else
                        {
                                p->bp = (char*)header;
                                p->cc = endofbuf - (char*)header;
                                return (n);
                        }
                }

                if(!dfp)
                {
                        /* convert between timestamp formats */
                        ts = header->ts;
                        pcap_header.ts.tv_sec = (int)(ts >> 32);
                        ts = (ts & 0xffffffffi64) * 1000000;
                        ts += 0x80000000; /* rounding */
                        pcap_header.ts.tv_usec = (int)(ts >> 32);
                        if (pcap_header.ts.tv_usec >= 1000000) {
                                pcap_header.ts.tv_usec -= 1000000;
                                pcap_header.ts.tv_sec++;
                        }
                }

                /* No underlaying filtering system. We need to filter on our own */
                if (p->fcode.bf_insns)
                {
                        if (bpf_filter(p->fcode.bf_insns, dp, packet_len, caplen) == 0)
                        {
                                /* Move to next packet */
                                header = (dag_record_t*)((char*)header + erf_record_len);
                                continue;
                        }
                }

                /* Fill the header for the user suppplied callback function */
                pcap_header.caplen = caplen;
                pcap_header.len = packet_len;

                /* Call the callback function */
                (*callback)(user, &pcap_header, dp);

                /* Move to next packet */
                header = (dag_record_t*)((char*)header + erf_record_len);

                /* Stop if the number of packets requested by user has been reached*/
                if (++n >= cnt && !PACKET_COUNT_IS_UNLIMITED(cnt))
                {
                        p->bp = (char*)header;
                        p->cc = endofbuf - (char*)header;
                        return (n);
                }
        }
        while((u_char*)header < endofbuf);

        return (1);
}
#endif /* HAVE_DAG_API */

/* Send a packet to the network */
static int
pcap_inject_win32(pcap_t *p, const void *buf, size_t size){
        LPPACKET PacketToSend;

        PacketToSend=PacketAllocatePacket();

        if (PacketToSend == NULL)
        {
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send error: PacketAllocatePacket failed");
                return (-1);
        }

        PacketInitPacket(PacketToSend, (PVOID)buf, (UINT)size);
        if(PacketSendPacket(p->adapter,PacketToSend,TRUE) == FALSE){
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send error: PacketSendPacket failed");
                PacketFreePacket(PacketToSend);
                return (-1);
        }

        PacketFreePacket(PacketToSend);

        /*
         * We assume it all got sent if "PacketSendPacket()" succeeded.
         * "pcap_inject()" is expected to return the number of bytes
         * sent.
         */
        return ((int)size);
}

static void
pcap_cleanup_win32(pcap_t *p)
{
        struct pcap_win *pw = p->priv;
        if (p->adapter != NULL) {
                PacketCloseAdapter(p->adapter);
                p->adapter = NULL;
        }
        if (pw->rfmon_selfstart)
        {
                PacketSetMonitorMode(p->opt.device, 0);
        }
        pcap_cleanup_live_common(p);
}

static int
pcap_activate_win32(pcap_t *p)
{
        struct pcap_win *pw = p->priv;
        NetType type;
        int res;
        char errbuf[PCAP_ERRBUF_SIZE+1];

        if (p->opt.rfmon) {
                /*
                 * Monitor mode is supported on Windows Vista and later.
                 */
                if (PacketGetMonitorMode(p->opt.device) == 1)
                {
                        pw->rfmon_selfstart = 0;
                }
                else
                {
                        if ((res = PacketSetMonitorMode(p->opt.device, 1)) != 1)
                        {
                                pw->rfmon_selfstart = 0;
                                // Monitor mode is not supported.
                                if (res == 0)
                                {
                                        return PCAP_ERROR_RFMON_NOTSUP;
                                }
                                else
                                {
                                        return PCAP_ERROR;
                                }
                        }
                        else
                        {
                                pw->rfmon_selfstart = 1;
                        }
                }
        }

        /* Init WinSock */
        wsockinit();

        p->adapter = PacketOpenAdapter(p->opt.device);

        if (p->adapter == NULL)
        {
                /* Adapter detected but we are not able to open it. Return failure. */
                pcap_win32_err_to_str(GetLastError(), errbuf);
                if (pw->rfmon_selfstart)
                {
                        PacketSetMonitorMode(p->opt.device, 0);
                }
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Error opening adapter: %s", errbuf);
                return (PCAP_ERROR);
        }

        /*get network type*/
        if(PacketGetNetType (p->adapter,&type) == FALSE)
        {
                pcap_win32_err_to_str(GetLastError(), errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "Cannot determine the network type: %s", errbuf);
                goto bad;
        }

        /*Set the linktype*/
        switch (type.LinkType)
        {
        case NdisMediumWan:
                p->linktype = DLT_EN10MB;
                break;

        case NdisMedium802_3:
                p->linktype = DLT_EN10MB;
                /*
                 * 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).
                 */
                p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
                /*
                 * If that fails, just leave the list empty.
                 */
                if (p->dlt_list != NULL) {
                        p->dlt_list[0] = DLT_EN10MB;
                        p->dlt_list[1] = DLT_DOCSIS;
                        p->dlt_count = 2;
                }
                break;

        case NdisMediumFddi:
                p->linktype = DLT_FDDI;
                break;

        case NdisMedium802_5:
                p->linktype = DLT_IEEE802;
                break;

        case NdisMediumArcnetRaw:
                p->linktype = DLT_ARCNET;
                break;

        case NdisMediumArcnet878_2:
                p->linktype = DLT_ARCNET;
                break;

        case NdisMediumAtm:
                p->linktype = DLT_ATM_RFC1483;
                break;

        case NdisMediumCHDLC:
                p->linktype = DLT_CHDLC;
                break;

        case NdisMediumPPPSerial:
                p->linktype = DLT_PPP_SERIAL;
                break;

        case NdisMediumNull:
                p->linktype = DLT_NULL;
                break;

        case NdisMediumBare80211:
                p->linktype = DLT_IEEE802_11;
                break;

        case NdisMediumRadio80211:
                p->linktype = DLT_IEEE802_11_RADIO;
                break;

        case NdisMediumPpi:
                p->linktype = DLT_PPI;
                break;

        default:
                p->linktype = DLT_EN10MB;                       /*an unknown adapter is assumed to be ethernet*/
                break;
        }

        /* Set promiscuous mode */
        if (p->opt.promisc)
        {

                if (PacketSetHwFilter(p->adapter,NDIS_PACKET_TYPE_PROMISCUOUS) == FALSE)
                {
                        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "failed to set hardware filter to promiscuous mode");
                        goto bad;
                }
        }
        else
        {
                if (PacketSetHwFilter(p->adapter,NDIS_PACKET_TYPE_ALL_LOCAL) == FALSE)
                {
                        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "failed to set hardware filter to non-promiscuous mode");
                        goto bad;
                }
        }

        /* Set the buffer size */
        p->bufsize = WIN32_DEFAULT_USER_BUFFER_SIZE;

        if(!(p->adapter->Flags & INFO_FLAG_DAG_CARD))
        {
        /*
         * Traditional Adapter
         */
                /*
                 * If the buffer size wasn't explicitly set, default to
                 * WIN32_DEFAULT_KERNEL_BUFFER_SIZE.
                 */
                if (p->opt.buffer_size == 0)
                        p->opt.buffer_size = WIN32_DEFAULT_KERNEL_BUFFER_SIZE;

                if(PacketSetBuff(p->adapter,p->opt.buffer_size)==FALSE)
                {
                        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: not enough memory to allocate the kernel buffer");
                        goto bad;
                }

                p->buffer = malloc(p->bufsize);
                if (p->buffer == NULL)
                {
                        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno));
                        goto bad;
                }

                if (p->opt.immediate)
                {
                        /* tell the driver to copy the buffer as soon as data arrives */
                        if(PacketSetMinToCopy(p->adapter,0)==FALSE)
                        {
                                pcap_win32_err_to_str(GetLastError(), errbuf);
                                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "Error calling PacketSetMinToCopy: %s",
                                    errbuf);
                                goto bad;
                        }
                }
                else
                {
                        /* tell the driver to copy the buffer only if it contains at least 16K */
                        if(PacketSetMinToCopy(p->adapter,16000)==FALSE)
                        {
                                pcap_win32_err_to_str(GetLastError(), errbuf);
                                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "Error calling PacketSetMinToCopy: %s",
                                    errbuf);
                                goto bad;
                        }
                }
        }
        else
#ifdef HAVE_DAG_API
        {
        /*
         * Dag Card
         */
                LONG    status;
                HKEY    dagkey;
                DWORD   lptype;
                DWORD   lpcbdata;
                int             postype = 0;
                char    keyname[512];

                pcap_snprintf(keyname, sizeof(keyname), "%s\\CardParams\\%s",
                        "SYSTEM\\CurrentControlSet\\Services\\DAG",
                        strstr(_strlwr(p->opt.device), "dag"));
                do
                {
                        status = RegOpenKeyEx(HKEY_LOCAL_MACHINE, keyname, 0, KEY_READ, &dagkey);
                        if(status != ERROR_SUCCESS)
                                break;

                        status = RegQueryValueEx(dagkey,
                                "PosType",
                                NULL,
                                &lptype,
                                (char*)&postype,
                                &lpcbdata);

                        if(status != ERROR_SUCCESS)
                        {
                                postype = 0;
                        }

                        RegCloseKey(dagkey);
                }
                while(FALSE);


                p->snapshot = PacketSetSnapLen(p->adapter, snaplen);

                /* Set the length of the FCS associated to any packet. This value
                 * will be subtracted to the packet length */
                pw->dag_fcs_bits = p->adapter->DagFcsLen;
        }
#else
        goto bad;
#endif /* HAVE_DAG_API */

        PacketSetReadTimeout(p->adapter, p->opt.timeout);

#ifdef HAVE_DAG_API
        if(p->adapter->Flags & INFO_FLAG_DAG_CARD)
        {
                /* install dag specific handlers for read and setfilter */
                p->read_op = pcap_read_win32_dag;
                p->setfilter_op = pcap_setfilter_win32_dag;
        }
        else
        {
#endif /* HAVE_DAG_API */
                /* install traditional npf handlers for read and setfilter */
                p->read_op = pcap_read_win32_npf;
                p->setfilter_op = pcap_setfilter_win32_npf;
#ifdef HAVE_DAG_API
        }
#endif /* HAVE_DAG_API */
        p->setdirection_op = NULL;      /* Not implemented. */
            /* XXX - can this be implemented on some versions of Windows? */
        p->inject_op = pcap_inject_win32;
        p->set_datalink_op = NULL;      /* can't change data link type */
        p->getnonblock_op = pcap_getnonblock_win32;
        p->setnonblock_op = pcap_setnonblock_win32;
        p->stats_op = pcap_stats_win32;
        p->stats_ex_op = pcap_stats_ex_win32;
        p->setbuff_op = pcap_setbuff_win32;
        p->setmode_op = pcap_setmode_win32;
        p->setmintocopy_op = pcap_setmintocopy_win32;
        p->getevent_op = pcap_getevent_win32;
        p->oid_get_request_op = pcap_oid_get_request_win32;
        p->oid_set_request_op = pcap_oid_set_request_win32;
        p->sendqueue_transmit_op = pcap_sendqueue_transmit_win32;
        p->setuserbuffer_op = pcap_setuserbuffer_win32;
        p->live_dump_op = pcap_live_dump_win32;
        p->live_dump_ended_op = pcap_live_dump_ended_win32;
        p->get_airpcap_handle_op = pcap_get_airpcap_handle_win32;
        p->cleanup_op = pcap_cleanup_win32;

        return (0);
bad:
        pcap_cleanup_win32(p);
        return (PCAP_ERROR);
}

/*
* Check if rfmon mode is supported on the pcap_t for Windows systems.
*/
static int
pcap_can_set_rfmon_win32(pcap_t *p)
{
        return (PacketIsMonitorModeSupported(p->opt.device) == 1);
}

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

        p = pcap_create_common(ebuf, sizeof(struct pcap_win));
        if (p == NULL)
                return (NULL);

        p->activate_op = pcap_activate_win32;
        p->can_set_rfmon_op = pcap_can_set_rfmon_win32;
        return (p);
}

static int
pcap_setfilter_win32_npf(pcap_t *p, struct bpf_program *fp)
{
        struct pcap_win *pw = p->priv;

        if(PacketSetBpf(p->adapter,fp)==FALSE){
                /*
                 * Kernel filter not installed.
                 *
                 * XXX - we don't know whether this failed because:
                 *
                 *  the kernel rejected the filter program as invalid,
                 *  in which case we should fall back on userland
                 *  filtering;
                 *
                 *  the kernel rejected the filter program as too big,
                 *  in which case we should again fall back on
                 *  userland filtering;
                 *
                 *  there was some other problem, in which case we
                 *  should probably report an error.
                 *
                 * For NPF devices, the Win32 status will be
                 * STATUS_INVALID_DEVICE_REQUEST for invalid
                 * filters, but I don't know what it'd be for
                 * other problems, and for some other devices
                 * it might not be set at all.
                 *
                 * So we just fall back on userland filtering in
                 * all cases.
                 */

                /*
                 * install_bpf_program() validates the program.
                 *
                 * XXX - what if we already have a filter in the kernel?
                 */
                if (install_bpf_program(p, fp) < 0)
                        return (-1);
                pw->filtering_in_kernel = 0;    /* filtering in userland */
                return (0);
        }

        /*
         * It worked.
         */
        pw->filtering_in_kernel = 1;    /* filtering in the kernel */

        /*
         * Discard any previously-received packets, as they might have
         * passed whatever filter was formerly in effect, but might
         * not pass this filter (BIOCSETF discards packets buffered
         * in the kernel, so you can lose packets in any case).
         */
        p->cc = 0;
        return (0);
}

/*
 * We filter at user level, since the kernel driver does't process the packets
 */
static int
pcap_setfilter_win32_dag(pcap_t *p, struct bpf_program *fp) {

        if(!fp)
        {
                strlcpy(p->errbuf, "setfilter: No filter specified", sizeof(p->errbuf));
                return (-1);
        }

        /* Install a user level filter */
        if (install_bpf_program(p, fp) < 0)
        {
                pcap_snprintf(p->errbuf, sizeof(p->errbuf),
                        "setfilter, unable to install the filter: %s", pcap_strerror(errno));
                return (-1);
        }

        return (0);
}

static int
pcap_getnonblock_win32(pcap_t *p)
{
        struct pcap_win *pw = p->priv;

        /*
         * XXX - if there were a PacketGetReadTimeout() call, we
         * would use it, and return 1 if the timeout is -1
         * and 0 otherwise.
         */
        return (pw->nonblock);
}

static int
pcap_setnonblock_win32(pcap_t *p, int nonblock)
{
        struct pcap_win *pw = p->priv;
        int newtimeout;
        char win_errbuf[PCAP_ERRBUF_SIZE+1];

        if (nonblock) {
                /*
                 * Set the packet buffer timeout to -1 for non-blocking
                 * mode.
                 */
                newtimeout = -1;
        } else {
                /*
                 * Restore the timeout set when the device was opened.
                 * (Note that this may be -1, in which case we're not
                 * really leaving non-blocking mode.  However, although
                 * the timeout argument to pcap_set_timeout() and
                 * pcap_open_live() is an int, you're not supposed to
                 * supply a negative value, so that "shouldn't happen".)
                 */
                newtimeout = p->opt.timeout;
        }
        if (!PacketSetReadTimeout(p->adapter, newtimeout)) {
                pcap_win32_err_to_str(GetLastError(), win_errbuf);
                pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "PacketSetReadTimeout: %s", win_errbuf);
                return (-1);
        }
        pw->nonblock = (newtimeout == -1);
        return (0);
}

static int
pcap_add_if_win32(pcap_if_list_t *devlistp, char *name, bpf_u_int32 flags,
    const char *description, char *errbuf)
{
        pcap_if_t *curdev;
        npf_if_addr if_addrs[MAX_NETWORK_ADDRESSES];
        LONG if_addr_size;
        int res = 0;

        if_addr_size = MAX_NETWORK_ADDRESSES;

        /*
         * Add an entry for this interface, with no addresses.
         */
        curdev = add_dev(devlistp, name, flags, description, errbuf);
        if (curdev == NULL) {
                /*
                 * Failure.
                 */
                return (-1);
        }

        /*
         * Get the list of addresses for the interface.
         */
        if (!PacketGetNetInfoEx((void *)name, if_addrs, &if_addr_size)) {
                /*
                 * Failure.
                 *
                 * We don't return an error, because this can happen with
                 * NdisWan interfaces, and we want to supply them even
                 * if we can't supply their addresses.
                 *
                 * We return an entry with an empty address list.
                 */
                return (0);
        }

        /*
         * Now add the addresses.
         */
        while (if_addr_size-- > 0) {
                /*
                 * "curdev" is an entry for this interface; add an entry for
                 * this address to its list of addresses.
                 */
                res = add_addr_to_dev(curdev,
                    (struct sockaddr *)&if_addrs[if_addr_size].IPAddress,
                    sizeof (struct sockaddr_storage),
                    (struct sockaddr *)&if_addrs[if_addr_size].SubnetMask,
                    sizeof (struct sockaddr_storage),
                    (struct sockaddr *)&if_addrs[if_addr_size].Broadcast,
                    sizeof (struct sockaddr_storage),
                    NULL,
                    0,
                    errbuf);
                if (res == -1) {
                        /*
                         * Failure.
                         */
                        break;
                }
        }

        return (res);
}

int
pcap_platform_finddevs(pcap_if_list_t *devlistp, char *errbuf)
{
        int ret = 0;
        const char *desc;
        char *AdaptersName;
        ULONG NameLength;
        char *name;
        char our_errbuf[PCAP_ERRBUF_SIZE+1];

        /*
         * Find out how big a buffer we need.
         *
         * This call should always return FALSE; if the error is
         * ERROR_INSUFFICIENT_BUFFER, NameLength will be set to
         * the size of the buffer we need, otherwise there's a
         * problem, and NameLength should be set to 0.
         *
         * It shouldn't require NameLength to be set, but,
         * at least as of WinPcap 4.1.3, it checks whether
         * NameLength is big enough before it checks for a
         * NULL buffer argument, so, while it'll still do
         * the right thing if NameLength is uninitialized and
         * whatever junk happens to be there is big enough
         * (because the pointer argument will be null), it's
         * still reading an uninitialized variable.
         */
        NameLength = 0;
        if (!PacketGetAdapterNames(NULL, &NameLength))
        {
                DWORD last_error = GetLastError();

                if (last_error != ERROR_INSUFFICIENT_BUFFER)
                {
                        pcap_win32_err_to_str(last_error, our_errbuf);
                        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "PacketGetAdapterNames: %s", our_errbuf);
                        return (-1);
                }
        }

        if (NameLength <= 0)
                return 0;
        AdaptersName = (char*) malloc(NameLength);
        if (AdaptersName == NULL)
        {
                pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "Cannot allocate enough memory to list the adapters.");
                return (-1);
        }

        if (!PacketGetAdapterNames(AdaptersName, &NameLength)) {
                pcap_win32_err_to_str(GetLastError(), our_errbuf);
                pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "PacketGetAdapterNames: %s",
                    our_errbuf);
                free(AdaptersName);
                return (-1);
        }

        /*
         * "PacketGetAdapterNames()" returned a list of
         * null-terminated ASCII interface name strings,
         * terminated by a null string, followed by a list
         * of null-terminated ASCII interface description
         * strings, terminated by a null string.
         * This means there are two ASCII nulls at the end
         * of the first list.
         *
         * Find the end of the first list; that's the
         * beginning of the second list.
         */
        desc = &AdaptersName[0];
        while (*desc != '\0' || *(desc + 1) != '\0')
                desc++;

        /*
         * Found it - "desc" points to the first of the two
         * nulls at the end of the list of names, so the
         * first byte of the list of descriptions is two bytes
         * after it.
         */
        desc += 2;

        /*
         * Loop over the elements in the first list.
         */
        name = &AdaptersName[0];
        while (*name != '\0') {
                bpf_u_int32 flags = 0;
#ifdef HAVE_PACKET_IS_LOOPBACK_ADAPTER
                /*
                 * Is this a loopback interface?
                 */
                if (PacketIsLoopbackAdapter(name)) {
                        /* Yes */
                        flags |= PCAP_IF_LOOPBACK;
                }
#endif

                /*
                 * Add an entry for this interface.
                 */
                if (pcap_add_if_win32(devlistp, name, flags, desc,
                    errbuf) == -1) {
                        /*
                         * Failure.
                         */
                        ret = -1;
                        break;
                }
                name += strlen(name) + 1;
                desc += strlen(desc) + 1;
        }

        free(AdaptersName);
        return (ret);
}