Have routines to set various internal debugging flags.

[libpcap] / inet.c

/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
/*
 * Copyright (c) 1994, 1995, 1996, 1997, 1998
 *      The Regents of the University of 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the Computer Systems
 *      Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef _WIN32
#include <pcap-stdinc.h>
#else /* _WIN32 */

#include <sys/param.h>
#ifndef MSDOS
#include <sys/file.h>
#endif
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif

struct mbuf;            /* Squelch compiler warnings on some platforms for */
struct rtentry;         /* declarations in <net/if.h> */
#include <net/if.h>
#include <netinet/in.h>
#endif /* _WIN32 */

#include <ctype.h>
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if !defined(_WIN32) && !defined(__BORLANDC__)
#include <unistd.h>
#endif /* !_WIN32 && !__BORLANDC__ */
#ifdef HAVE_LIMITS_H
#include <limits.h>
#else
#define INT_MAX         2147483647
#endif

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

/* Not all systems have IFF_LOOPBACK */
#ifdef IFF_LOOPBACK
#define ISLOOPBACK(name, flags) ((flags) & IFF_LOOPBACK)
#else
#define ISLOOPBACK(name, flags) ((name)[0] == 'l' && (name)[1] == 'o' && \
    (isdigit((unsigned char)((name)[2])) || (name)[2] == '\0'))
#endif

#ifdef IFF_UP
#define ISUP(flags) ((flags) & IFF_UP)
#else
#define ISUP(flags) 0
#endif

#ifdef IFF_RUNNING
#define ISRUNNING(flags) ((flags) & IFF_RUNNING)
#else
#define ISRUNNING(flags) 0
#endif

struct sockaddr *
dup_sockaddr(struct sockaddr *sa, size_t sa_length)
{
        struct sockaddr *newsa;

        if ((newsa = malloc(sa_length)) == NULL)
                return (NULL);
        return (memcpy(newsa, sa, sa_length));
}

/*
 * Construct a "figure of merit" for an interface, for use when sorting
 * the list of interfaces, in which interfaces that are up are superior
 * to interfaces that aren't up, interfaces that are up and running are
 * superior to interfaces that are up but not running, and non-loopback
 * interfaces that are up and running are superior to loopback interfaces,
 * and interfaces with the same flags have a figure of merit that's higher
 * the lower the instance number.
 *
 * The goal is to try to put the interfaces most likely to be useful for
 * capture at the beginning of the list.
 *
 * The figure of merit, which is lower the "better" the interface is,
 * has the uppermost bit set if the interface isn't running, the bit
 * below that set if the interface isn't up, the bit below that set
 * if the interface is a loopback interface, and the interface index
 * in the 29 bits below that.  (Yes, we assume u_int is 32 bits.)
 */
static u_int
get_figure_of_merit(pcap_if_t *dev)
{
        const char *cp;
        u_int n;

        if (strcmp(dev->name, "any") == 0) {
                /*
                 * Give the "any" device an artificially high instance
                 * number, so it shows up after all other non-loopback
                 * interfaces.
                 */
                n = 0x1FFFFFFF; /* 29 all-1 bits */
        } else {
                /*
                 * A number at the end of the device name string is
                 * assumed to be a unit number.
                 */
                cp = dev->name + strlen(dev->name) - 1;
                while (cp-1 >= dev->name && *(cp-1) >= '0' && *(cp-1) <= '9')
                        cp--;
                if (*cp >= '0' && *cp <= '9')
                        n = atoi(cp);
                else
                        n = 0;
        }
        if (!(dev->flags & PCAP_IF_RUNNING))
                n |= 0x80000000;
        if (!(dev->flags & PCAP_IF_UP))
                n |= 0x40000000;
        if (dev->flags & PCAP_IF_LOOPBACK)
                n |= 0x20000000;
        return (n);
}

/*
 * Look for a given device in the specified list of devices.
 *
 * If we find it, return 0 and set *curdev_ret to point to it.
 *
 * If we don't find it, check whether we can open it:
 *
 *     If that fails with PCAP_ERROR_NO_SUCH_DEVICE or
 *     PCAP_ERROR_IFACE_NOT_UP, don't attempt to add an entry for
 *     it, as that probably means it exists but doesn't support
 *     packet capture.
 *
 *     Otherwise, attempt to add an entry for it, with the specified
 *     ifnet flags and description, and, if that succeeds, return 0
 *     and set *curdev_ret to point to the new entry, otherwise
 *     return PCAP_ERROR and set errbuf to an error message.
 */
int
add_or_find_if(pcap_if_t **curdev_ret, pcap_if_t **alldevs, const char *name,
    u_int flags, const char *description, char *errbuf)
{
        pcap_t *p;
        pcap_if_t *curdev, *prevdev, *nextdev;
        u_int this_figure_of_merit, nextdev_figure_of_merit;
        char open_errbuf[PCAP_ERRBUF_SIZE];
        int ret;

        /*
         * Is there already an entry in the list for this interface?
         */
        for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) {
                if (strcmp(name, curdev->name) == 0)
                        break;  /* yes, we found it */
        }

        if (curdev == NULL) {
                /*
                 * No, we didn't find it.
                 *
                 * Can we open this interface for live capture?
                 *
                 * We do this check so that interfaces that are
                 * supplied by the interface enumeration mechanism
                 * we're using but that don't support packet capture
                 * aren't included in the list.  Loopback interfaces
                 * on Solaris are an example of this; we don't just
                 * omit loopback interfaces on all platforms because
                 * you *can* capture on loopback interfaces on some
                 * OSes.
                 *
                 * On OS X, we don't do this check if the device
                 * name begins with "wlt"; at least some versions
                 * of OS X offer monitor mode capturing by having
                 * a separate "monitor mode" device for each wireless
                 * adapter, rather than by implementing the ioctls
                 * that {Free,Net,Open,DragonFly}BSD provide.
                 * Opening that device puts the adapter into monitor
                 * mode, which, at least for some adapters, causes
                 * them to deassociate from the network with which
                 * they're associated.
                 *
                 * Instead, we try to open the corresponding "en"
                 * device (so that we don't end up with, for users
                 * without sufficient privilege to open capture
                 * devices, a list of adapters that only includes
                 * the wlt devices).
                 */
#ifdef __APPLE__
                if (strncmp(name, "wlt", 3) == 0) {
                        char *en_name;
                        size_t en_name_len;

                        /*
                         * Try to allocate a buffer for the "en"
                         * device's name.
                         */
                        en_name_len = strlen(name) - 1;
                        en_name = malloc(en_name_len + 1);
                        if (en_name == NULL) {
                                (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                                    "malloc: %s", pcap_strerror(errno));
                                return (-1);
                        }
                        strcpy(en_name, "en");
                        strcat(en_name, name + 3);
                        p = pcap_create(en_name, open_errbuf);
                        free(en_name);
                } else
#endif /* __APPLE */
                p = pcap_create(name, open_errbuf);
                if (p == NULL) {
                        /*
                         * The attempt to create the pcap_t failed;
                         * that's probably an indication that we're
                         * out of memory.
                         *
                         * Don't bother including this interface,
                         * but don't treat it as an error.
                         */
                        *curdev_ret = NULL;
                        return (0);
                }
                /* Small snaplen, so we don't try to allocate much memory. */
                pcap_set_snaplen(p, 68);
                ret = pcap_activate(p);
                pcap_close(p);
                switch (ret) {

                case PCAP_ERROR_NO_SUCH_DEVICE:
                case PCAP_ERROR_IFACE_NOT_UP:
                        /*
                         * We expect these two errors - they're the
                         * reason we try to open the device.
                         *
                         * PCAP_ERROR_NO_SUCH_DEVICE typically means
                         * "there's no such device *known to the
                         * OS's capture mechanism*", so, even though
                         * it might be a valid network interface, you
                         * can't capture on it (e.g., the loopback
                         * device in Solaris up to Solaris 10, or
                         * the vmnet devices in OS X with VMware
                         * Fusion).  We don't include those devices
                         * in our list of devices, as there's no
                         * point in doing so - they're not available
                         * for capture.
                         *
                         * PCAP_ERROR_IFACE_NOT_UP means that the
                         * OS's capture mechanism doesn't work on
                         * interfaces not marked as up; some capture
                         * mechanisms *do* support that, so we no
                         * longer reject those interfaces out of hand,
                         * but we *do* want to reject them if they
                         * can't be opened for capture.
                         */
                        *curdev_ret = NULL;
                        return (0);
                }

                /*
                 * Yes, we can open it, or we can't, for some other
                 * reason.
                 *
                 * If we can open it, we want to offer it for
                 * capture, as you can capture on it.  If we can't,
                 * we want to offer it for capture, so that, if
                 * the user tries to capture on it, they'll get
                 * an error and they'll know why they can't
                 * capture on it (e.g., insufficient permissions)
                 * or they'll report it as a problem (and then
                 * have the error message to provide as information).
                 *
                 * Allocate a new entry.
                 */
                curdev = malloc(sizeof(pcap_if_t));
                if (curdev == NULL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        return (-1);
                }

                /*
                 * Fill in the entry.
                 */
                curdev->next = NULL;
                curdev->name = strdup(name);
                if (curdev->name == NULL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        free(curdev);
                        return (-1);
                }
                if (description != NULL) {
                        /*
                         * We have a description for this interface.
                         */
                        curdev->description = strdup(description);
                        if (curdev->description == NULL) {
                                (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                                    "malloc: %s", pcap_strerror(errno));
                                free(curdev->name);
                                free(curdev);
                                return (-1);
                        }
                } else {
                        /*
                         * We don't.
                         */
                        curdev->description = NULL;
                }
                curdev->addresses = NULL;       /* list starts out as empty */
                curdev->flags = 0;
                if (ISLOOPBACK(name, flags))
                        curdev->flags |= PCAP_IF_LOOPBACK;
                if (ISUP(flags))
                        curdev->flags |= PCAP_IF_UP;
                if (ISRUNNING(flags))
                        curdev->flags |= PCAP_IF_RUNNING;

                /*
                 * Add it to the list, in the appropriate location.
                 * First, get the "figure of merit" for this
                 * interface.
                 */
                this_figure_of_merit = get_figure_of_merit(curdev);

                /*
                 * Now look for the last interface with an figure of merit
                 * less than or equal to the new interface's figure of
                 * merit.
                 *
                 * We start with "prevdev" being NULL, meaning we're before
                 * the first element in the list.
                 */
                prevdev = NULL;
                for (;;) {
                        /*
                         * Get the interface after this one.
                         */
                        if (prevdev == NULL) {
                                /*
                                 * The next element is the first element.
                                 */
                                nextdev = *alldevs;
                        } else
                                nextdev = prevdev->next;

                        /*
                         * Are we at the end of the list?
                         */
                        if (nextdev == NULL) {
                                /*
                                 * Yes - we have to put the new entry
                                 * after "prevdev".
                                 */
                                break;
                        }

                        /*
                         * Is the new interface's figure of merit less
                         * than the next interface's figure of merit,
                         * meaning that the new interface is better
                         * than the next interface?
                         */
                        nextdev_figure_of_merit = get_figure_of_merit(nextdev);
                        if (this_figure_of_merit < nextdev_figure_of_merit) {
                                /*
                                 * Yes - we should put the new entry
                                 * before "nextdev", i.e. after "prevdev".
                                 */
                                break;
                        }

                        prevdev = nextdev;
                }

                /*
                 * Insert before "nextdev".
                 */
                curdev->next = nextdev;

                /*
                 * Insert after "prevdev" - unless "prevdev" is null,
                 * in which case this is the first interface.
                 */
                if (prevdev == NULL) {
                        /*
                         * This is the first interface.  Pass back a
                         * pointer to it, and put "curdev" before
                         * "nextdev".
                         */
                        *alldevs = curdev;
                } else
                        prevdev->next = curdev;
        }

        *curdev_ret = curdev;
        return (0);
}

/*
 * Try to get a description for a given device.
 * Returns a mallocated description if it could and NULL if it couldn't.
 *
 * XXX - on FreeBSDs that support it, should it get the sysctl named
 * "dev.{adapter family name}.{adapter unit}.%desc" to get a description
 * of the adapter?  Note that "dev.an.0.%desc" is "Aironet PC4500/PC4800"
 * with my Cisco 350 card, so the name isn't entirely descriptive.  The
 * "dev.an.0.%pnpinfo" has a better description, although one might argue
 * that the problem is really a driver bug - if it can find out that it's
 * a Cisco 340 or 350, rather than an old Aironet card, it should use
 * that in the description.
 *
 * Do NetBSD, DragonflyBSD, or OpenBSD support this as well?  FreeBSD
 * and OpenBSD let you get a description, but it's not generated by the OS,
 * it's set with another ioctl that ifconfig supports; we use that to get
 * a description in FreeBSD and OpenBSD, but if there is no such
 * description available, it still might be nice to get some description
 * string based on the device type or something such as that.
 *
 * In OS X, the System Configuration framework can apparently return
 * names in 10.4 and later.
 *
 * It also appears that freedesktop.org's HAL offers an "info.product"
 * string, but the HAL specification says it "should not be used in any
 * UI" and "subsystem/capability specific properties" should be used
 * instead and, in any case, I think HAL is being deprecated in
 * favor of other stuff such as DeviceKit.  DeviceKit doesn't appear
 * to have any obvious product information for devices, but maybe
 * I haven't looked hard enough.
 *
 * Using the System Configuration framework, or HAL, or DeviceKit, or
 * whatever, would require that libpcap applications be linked with
 * the frameworks/libraries in question.  That shouldn't be a problem
 * for programs linking with the shared version of libpcap (unless
 * you're running on AIX - which I think is the only UN*X that doesn't
 * support linking a shared library with other libraries on which it
 * depends, and having an executable linked only with the first shared
 * library automatically pick up the other libraries when started -
 * and using HAL or whatever).  Programs linked with the static
 * version of libpcap would have to use pcap-config with the --static
 * flag in order to get the right linker flags in order to pick up
 * the additional libraries/frameworks; those programs need that anyway
 * for libpcap 1.1 and beyond on Linux, as, by default, it requires
 * -lnl.
 *
 * Do any other UN*Xes, or desktop environments support getting a
 * description?
 */
static char *
get_if_description(const char *name)
{
#ifdef SIOCGIFDESCR
        char *description = NULL;
        int s;
        struct ifreq ifrdesc;
#ifndef IFDESCRSIZE
        size_t descrlen = 64;
#else
        size_t descrlen = IFDESCRSIZE;
#endif /* IFDESCRSIZE */

        /*
         * Get the description for the interface.
         */
        memset(&ifrdesc, 0, sizeof ifrdesc);
        strlcpy(ifrdesc.ifr_name, name, sizeof ifrdesc.ifr_name);
        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s >= 0) {
#ifdef __FreeBSD__
                /*
                 * On FreeBSD, if the buffer isn't big enough for the
                 * description, the ioctl succeeds, but the description
                 * isn't copied, ifr_buffer.length is set to the description
                 * length, and ifr_buffer.buffer is set to NULL.
                 */
                for (;;) {
                        free(description);
                        if ((description = malloc(descrlen)) != NULL) {
                                ifrdesc.ifr_buffer.buffer = description;
                                ifrdesc.ifr_buffer.length = descrlen;
                                if (ioctl(s, SIOCGIFDESCR, &ifrdesc) == 0) {
                                        if (ifrdesc.ifr_buffer.buffer ==
                                            description)
                                                break;
                                        else
                                                descrlen = ifrdesc.ifr_buffer.length;
                                } else {
                                        /*
                                         * Failed to get interface description.
                                         */
                                        free(description);
                                        description = NULL;
                                        break;
                                }
                        } else
                                break;
                }
#else /* __FreeBSD__ */
                /*
                 * The only other OS that currently supports
                 * SIOCGIFDESCR is OpenBSD, and it has no way
                 * to get the description length - it's clamped
                 * to a maximum of IFDESCRSIZE.
                 */
                if ((description = malloc(descrlen)) != NULL) {
                        ifrdesc.ifr_data = (caddr_t)description;
                        if (ioctl(s, SIOCGIFDESCR, &ifrdesc) != 0) {
                                /*
                                 * Failed to get interface description.
                                 */
                                free(description);
                                description = NULL;
                        }
                }
#endif /* __FreeBSD__ */
                close(s);
                if (description != NULL && strlen(description) == 0) {
                        free(description);
                        description = NULL;
                }
        }

        return (description);
#else /* SIOCGIFDESCR */
        return (NULL);
#endif /* SIOCGIFDESCR */
}

/*
 * Try to get a description for a given device, and then look for that
 * device in the specified list of devices.
 *
 * If we find it, then, if the specified address isn't null, add it to
 * the list of addresses for the device and return 0.
 *
 * If we don't find it, check whether we can open it:
 *
 *     If that fails with PCAP_ERROR_NO_SUCH_DEVICE or
 *     PCAP_ERROR_IFACE_NOT_UP, don't attempt to add an entry for
 *     it, as that probably means it exists but doesn't support
 *     packet capture.
 *
 *     Otherwise, attempt to add an entry for it, with the specified
 *     ifnet flags and description, and, if that succeeds, add the
 *     specified address to its list of addresses if that address is
 *     non-null, set *curdev_ret to point to the new entry, and
 *     return 0, otherwise return PCAP_ERROR and set errbuf to an
 *     error message.
 *
 * (We can get called with a null address because we might get a list
 * of interface name/address combinations from the underlying OS, with
 * the address being absent in some cases, rather than a list of
 * interfaces with each interface having a list of addresses, so this
 * call may be the only call made to add to the list, and we want to
 * add interfaces even if they have no addresses.)
 */
int
add_addr_to_iflist(pcap_if_t **alldevs, const char *name, u_int flags,
    struct sockaddr *addr, size_t addr_size,
    struct sockaddr *netmask, size_t netmask_size,
    struct sockaddr *broadaddr, size_t broadaddr_size,
    struct sockaddr *dstaddr, size_t dstaddr_size,
    char *errbuf)
{
        char *description;
        pcap_if_t *curdev;

        description = get_if_description(name);
        if (add_or_find_if(&curdev, alldevs, name, flags, description,
            errbuf) == -1) {
                free(description);
                /*
                 * Error - give up.
                 */
                return (-1);
        }
        free(description);
        if (curdev == NULL) {
                /*
                 * Device wasn't added because it can't be opened.
                 * Not a fatal error.
                 */
                return (0);
        }

        if (addr == NULL) {
                /*
                 * There's no address to add; this entry just meant
                 * "here's a new interface".
                 */
                return (0);
        }

        /*
         * "curdev" is an entry for this interface, and we have an
         * address for it; add an entry for that address to the
         * interface's list of addresses.
         *
         * Allocate the new entry and fill it in.
         */
        return (add_addr_to_dev(curdev, addr, addr_size, netmask,
            netmask_size, broadaddr, broadaddr_size, dstaddr,
            dstaddr_size, errbuf));
}

/*
 * Add an entry to the list of addresses for an interface.
 * "curdev" is the entry for that interface.
 * If this is the first IP address added to the interface, move it
 * in the list as appropriate.
 */
int
add_addr_to_dev(pcap_if_t *curdev,
    struct sockaddr *addr, size_t addr_size,
    struct sockaddr *netmask, size_t netmask_size,
    struct sockaddr *broadaddr, size_t broadaddr_size,
    struct sockaddr *dstaddr, size_t dstaddr_size,
    char *errbuf)
{
        pcap_addr_t *curaddr, *prevaddr, *nextaddr;

        curaddr = malloc(sizeof(pcap_addr_t));
        if (curaddr == NULL) {
                (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "malloc: %s", pcap_strerror(errno));
                return (-1);
        }

        curaddr->next = NULL;
        if (addr != NULL) {
                curaddr->addr = dup_sockaddr(addr, addr_size);
                if (curaddr->addr == NULL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        free(curaddr);
                        return (-1);
                }
        } else
                curaddr->addr = NULL;

        if (netmask != NULL) {
                curaddr->netmask = dup_sockaddr(netmask, netmask_size);
                if (curaddr->netmask == NULL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        if (curaddr->addr != NULL)
                                free(curaddr->addr);
                        free(curaddr);
                        return (-1);
                }
        } else
                curaddr->netmask = NULL;

        if (broadaddr != NULL) {
                curaddr->broadaddr = dup_sockaddr(broadaddr, broadaddr_size);
                if (curaddr->broadaddr == NULL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        if (curaddr->netmask != NULL)
                                free(curaddr->netmask);
                        if (curaddr->addr != NULL)
                                free(curaddr->addr);
                        free(curaddr);
                        return (-1);
                }
        } else
                curaddr->broadaddr = NULL;

        if (dstaddr != NULL) {
                curaddr->dstaddr = dup_sockaddr(dstaddr, dstaddr_size);
                if (curaddr->dstaddr == NULL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        if (curaddr->broadaddr != NULL)
                                free(curaddr->broadaddr);
                        if (curaddr->netmask != NULL)
                                free(curaddr->netmask);
                        if (curaddr->addr != NULL)
                                free(curaddr->addr);
                        free(curaddr);
                        return (-1);
                }
        } else
                curaddr->dstaddr = NULL;

        /*
         * Find the end of the list of addresses.
         */
        for (prevaddr = curdev->addresses; prevaddr != NULL; prevaddr = nextaddr) {
                nextaddr = prevaddr->next;
                if (nextaddr == NULL) {
                        /*
                         * This is the end of the list.
                         */
                        break;
                }
        }

        if (prevaddr == NULL) {
                /*
                 * The list was empty; this is the first member.
                 */
                curdev->addresses = curaddr;
        } else {
                /*
                 * "prevaddr" is the last member of the list; append
                 * this member to it.
                 */
                prevaddr->next = curaddr;
        }

        return (0);
}

/*
 * Look for a given device in the specified list of devices.
 *
 * If we find it, return 0.
 *
 * If we don't find it, check whether we can open it:
 *
 *     If that fails with PCAP_ERROR_NO_SUCH_DEVICE or
 *     PCAP_ERROR_IFACE_NOT_UP, don't attempt to add an entry for
 *     it, as that probably means it exists but doesn't support
 *     packet capture.
 *
 *     Otherwise, attempt to add an entry for it, with the specified
 *     ifnet flags and description, and, if that succeeds, return 0
 *     and set *curdev_ret to point to the new entry, otherwise
 *     return PCAP_ERROR and set errbuf to an error message.
 */
int
pcap_add_if(pcap_if_t **devlist, const char *name, u_int flags,
    const char *description, char *errbuf)
{
        pcap_if_t *curdev;

        return (add_or_find_if(&curdev, devlist, name, flags, description,
            errbuf));
}


/*
 * Free a list of interfaces.
 */
void
pcap_freealldevs(pcap_if_t *alldevs)
{
        pcap_if_t *curdev, *nextdev;
        pcap_addr_t *curaddr, *nextaddr;

        for (curdev = alldevs; curdev != NULL; curdev = nextdev) {
                nextdev = curdev->next;

                /*
                 * Free all addresses.
                 */
                for (curaddr = curdev->addresses; curaddr != NULL; curaddr = nextaddr) {
                        nextaddr = curaddr->next;
                        if (curaddr->addr)
                                free(curaddr->addr);
                        if (curaddr->netmask)
                                free(curaddr->netmask);
                        if (curaddr->broadaddr)
                                free(curaddr->broadaddr);
                        if (curaddr->dstaddr)
                                free(curaddr->dstaddr);
                        free(curaddr);
                }

                /*
                 * Free the name string.
                 */
                free(curdev->name);

                /*
                 * Free the description string, if any.
                 */
                if (curdev->description != NULL)
                        free(curdev->description);

                /*
                 * Free the interface.
                 */
                free(curdev);
        }
}

#if !defined(_WIN32) && !defined(MSDOS)

/*
 * Return the name of a network interface attached to the system, or NULL
 * if none can be found.  The interface must be configured up; the
 * lowest unit number is preferred; loopback is ignored.
 */
char *
pcap_lookupdev(errbuf)
        register char *errbuf;
{
        pcap_if_t *alldevs;
/* for old BSD systems, including bsdi3 */
#ifndef IF_NAMESIZE
#define IF_NAMESIZE IFNAMSIZ
#endif
        static char device[IF_NAMESIZE + 1];
        char *ret;

        if (pcap_findalldevs(&alldevs, errbuf) == -1)
                return (NULL);

        if (alldevs == NULL || (alldevs->flags & PCAP_IF_LOOPBACK)) {
                /*
                 * There are no devices on the list, or the first device
                 * on the list is a loopback device, which means there
                 * are no non-loopback devices on the list.  This means
                 * we can't return any device.
                 *
                 * XXX - why not return a loopback device?  If we can't
                 * capture on it, it won't be on the list, and if it's
                 * on the list, there aren't any non-loopback devices,
                 * so why not just supply it as the default device?
                 */
                (void)strlcpy(errbuf, "no suitable device found",
                    PCAP_ERRBUF_SIZE);
                ret = NULL;
        } else {
                /*
                 * Return the name of the first device on the list.
                 */
                (void)strlcpy(device, alldevs->name, sizeof(device));
                ret = device;
        }

        pcap_freealldevs(alldevs);
        return (ret);
}

int
pcap_lookupnet(device, netp, maskp, errbuf)
        register const char *device;
        register bpf_u_int32 *netp, *maskp;
        register char *errbuf;
{
        register int fd;
        register struct sockaddr_in *sin4;
        struct ifreq ifr;

        /*
         * The pseudo-device "any" listens on all interfaces and therefore
         * has the network address and -mask "0.0.0.0" therefore catching
         * all traffic. Using NULL for the interface is the same as "any".
         */
        if (!device || strcmp(device, "any") == 0
#ifdef HAVE_DAG_API
            || strstr(device, "dag") != NULL
#endif
#ifdef HAVE_SEPTEL_API
            || strstr(device, "septel") != NULL
#endif
#ifdef PCAP_SUPPORT_BT
            || strstr(device, "bluetooth") != NULL
#endif
#ifdef PCAP_SUPPORT_USB
            || strstr(device, "usbmon") != NULL
#endif
#ifdef HAVE_SNF_API
            || strstr(device, "snf") != NULL
#endif
            ) {
                *netp = *maskp = 0;
                return 0;
        }

        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0) {
                (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
                    pcap_strerror(errno));
                return (-1);
        }
        memset(&ifr, 0, sizeof(ifr));
#ifdef linux
        /* XXX Work around Linux kernel bug */
        ifr.ifr_addr.sa_family = AF_INET;
#endif
        (void)strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
        if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
                if (errno == EADDRNOTAVAIL) {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "%s: no IPv4 address assigned", device);
                } else {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "SIOCGIFADDR: %s: %s",
                            device, pcap_strerror(errno));
                }
                (void)close(fd);
                return (-1);
        }
        sin4 = (struct sockaddr_in *)&ifr.ifr_addr;
        *netp = sin4->sin_addr.s_addr;
        memset(&ifr, 0, sizeof(ifr));
#ifdef linux
        /* XXX Work around Linux kernel bug */
        ifr.ifr_addr.sa_family = AF_INET;
#endif
        (void)strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
        if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
                (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
                (void)close(fd);
                return (-1);
        }
        (void)close(fd);
        *maskp = sin4->sin_addr.s_addr;
        if (*maskp == 0) {
                if (IN_CLASSA(*netp))
                        *maskp = IN_CLASSA_NET;
                else if (IN_CLASSB(*netp))
                        *maskp = IN_CLASSB_NET;
                else if (IN_CLASSC(*netp))
                        *maskp = IN_CLASSC_NET;
                else {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "inet class for 0x%x unknown", *netp);
                        return (-1);
                }
        }
        *netp &= *maskp;
        return (0);
}

#elif defined(_WIN32)

/*
 * Return the name of a network interface attached to the system, or NULL
 * if none can be found.  The interface must be configured up; the
 * lowest unit number is preferred; loopback is ignored.
 *
 * In the best of all possible worlds, this would be the same as on
 * UN*X, but there may be software that expects this to return a
 * full list of devices after the first device.
 */
char *
pcap_lookupdev(errbuf)
        register char *errbuf;
{
        DWORD dwVersion;
        DWORD dwWindowsMajorVersion;
        char our_errbuf[PCAP_ERRBUF_SIZE+1];

        dwVersion = GetVersion();       /* get the OS version */
        dwWindowsMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));

        if (dwVersion >= 0x80000000 && dwWindowsMajorVersion >= 4) {
                /*
                 * Windows 95, 98, ME.
                 */
                ULONG NameLength = 8192;
                static char AdaptersName[8192];

                if (PacketGetAdapterNames(AdaptersName,&NameLength) )
                        return (AdaptersName);
                else
                        return NULL;
        } else {
                /*
                 * Windows NT (NT 4.0, W2K, WXP). Convert the names to UNICODE for backward compatibility
                 */
                ULONG NameLength = 8192;
                static WCHAR AdaptersName[8192];
                char *tAstr;
                WCHAR *tUstr;
                WCHAR *TAdaptersName = (WCHAR*)malloc(8192 * sizeof(WCHAR));
                int NAdapts = 0;

                if(TAdaptersName == NULL)
                {
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "memory allocation failure");
                        return NULL;
                }

                if ( !PacketGetAdapterNames((PTSTR)TAdaptersName,&NameLength) )
                {
                        pcap_win32_err_to_str(GetLastError(), our_errbuf);
                        (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                                "PacketGetAdapterNames: %s", our_errbuf);
                        free(TAdaptersName);
                        return NULL;
                }


                tAstr = (char*)TAdaptersName;
                tUstr = (WCHAR*)AdaptersName;

                /*
                 * Convert and copy the device names
                 */
                while(sscanf(tAstr, "%S", tUstr) > 0)
                {
                        tAstr += strlen(tAstr) + 1;
                        tUstr += wcslen(tUstr) + 1;
                        NAdapts ++;
                }

                tAstr++;
                *tUstr = 0;
                tUstr++;

                /*
                 * Copy the descriptions
                 */
                while(NAdapts--)
                {
                        char* tmp = (char*)tUstr;
                        strcpy(tmp, tAstr);
                        tmp += strlen(tAstr) + 1;
                        tUstr = (WCHAR*)tmp;
                        tAstr += strlen(tAstr) + 1;
                }

                free(TAdaptersName);
                return (char *)(AdaptersName);
        }
}


int
pcap_lookupnet(device, netp, maskp, errbuf)
        register const char *device;
        register bpf_u_int32 *netp, *maskp;
        register char *errbuf;
{
        /*
         * We need only the first IPv4 address, so we must scan the array returned by PacketGetNetInfo()
         * in order to skip non IPv4 (i.e. IPv6 addresses)
         */
        npf_if_addr if_addrs[MAX_NETWORK_ADDRESSES];
        LONG if_addr_size = 1;
        struct sockaddr_in *t_addr;
        unsigned int i;

        if (!PacketGetNetInfoEx((void *)device, if_addrs, &if_addr_size)) {
                *netp = *maskp = 0;
                return (0);
        }

        for(i=0; i<MAX_NETWORK_ADDRESSES; i++)
        {
                if(if_addrs[i].IPAddress.ss_family == AF_INET)
                {
                        t_addr = (struct sockaddr_in *) &(if_addrs[i].IPAddress);
                        *netp = t_addr->sin_addr.S_un.S_addr;
                        t_addr = (struct sockaddr_in *) &(if_addrs[i].SubnetMask);
                        *maskp = t_addr->sin_addr.S_un.S_addr;

                        *netp &= *maskp;
                        return (0);
                }

        }

        *netp = *maskp = 0;
        return (0);
}

#endif /* !_WIN32 && !MSDOS */