Make the "is_loopback" field of a "pcap_if" structure a general "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.
 */

#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /tcpdump/master/libpcap/inet.c,v 1.43 2001-10-28 02:31:49 guy Exp $ (LBL)";
#endif

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

#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif
#include <sys/time.h>                           /* concession to AIX */

struct mbuf;
struct rtentry;
#include <net/if.h>
#include <netinet/in.h>

#include <ctype.h>
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#else
#define INT_MAX         2147483647
#endif
#ifdef HAVE_IFADDRS_H
#include <ifaddrs.h>
#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

/*
 * This is fun.
 *
 * In older BSD systems, socket addresses were fixed-length, and
 * "sizeof (struct sockaddr)" gave the size of the structure.
 * All addresses fit within a "struct sockaddr".
 *
 * In newer BSD systems, the socket address is variable-length, and
 * there's an "sa_len" field giving the length of the structure;
 * this allows socket addresses to be longer than 2 bytes of family
 * and 14 bytes of data.
 *
 * Some commercial UNIXes use the old BSD scheme, and some might use
 * the new BSD scheme.
 *
 * GNU libc uses neither scheme, but has an "SA_LEN()" macro that
 * determines the size based on the address family.
 */
#ifndef SA_LEN
#ifdef HAVE_SOCKADDR_SA_LEN
#define SA_LEN(addr)    ((addr)->sa_len)
#else /* HAVE_SOCKADDR_SA_LEN */
#define SA_LEN(addr)    (sizeof (struct sockaddr))
#endif /* HAVE_SOCKADDR_SA_LEN */
#endif /* SA_LEN */

static struct sockaddr *
dup_sockaddr(struct sockaddr *sa)
{
        struct sockaddr *newsa;
        unsigned int size;
        
        size = SA_LEN(sa);
        if ((newsa = malloc(size)) == NULL)
                return (NULL);
        return (memcpy(newsa, sa, size));
}

static int
get_instance(char *name)
{
        char *cp, *endcp;
        int n;

        if (strcmp(name, "any") == 0) {
                /*
                 * Give the "any" device an artificially high instance
                 * number, so it shows up after all other non-loopback
                 * interfaces.
                 */
                return INT_MAX;
        }

        endcp = name + strlen(name);
        for (cp = name; cp < endcp && !isdigit((unsigned char)*cp); ++cp)
                continue;

        if (isdigit((unsigned char)*cp))
                n = atoi(cp);
        else
                n = 0;
        return (n);
}

static int
add_or_find_if(pcap_if_t **curdev_ret, pcap_if_t **alldevs, char *name,
    u_int flags, char *errbuf)
{
        pcap_t *p;
        pcap_if_t *curdev, *prevdev, *nextdev;
        int this_instance;

        /*
         * Can we open this interface for live capture?
         */
        p = pcap_open_live(name, 68, 0, 0, errbuf);
        if (p == NULL) {
                /*
                 * No.  Don't bother including it.
                 * Don't treat this as an error, though.
                 */
                *curdev_ret = NULL;
                return (0);
        }
        pcap_close(p);

        /*
         * 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.
                 * Allocate a new entry.
                 */
                curdev = malloc(sizeof(pcap_if_t));
                if (curdev == NULL) {
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        return (-1);
                }
                
                /*
                 * Fill in the entry.
                 */
                curdev->next = NULL;
                curdev->name = malloc(strlen(name) + 1);
                strcpy(curdev->name, name);
                curdev->description = NULL;     /* not available */
                curdev->addresses = NULL;       /* list starts out as empty */
                curdev->flags = 0;
                if (ISLOOPBACK(name, flags))
                        curdev->flags |= PCAP_IF_LOOPBACK;

                /*
                 * Add it to the list, in the appropriate location.
                 * First, get the instance number of this interface.
                 */
                this_instance = get_instance(name);

                /*
                 * Now look for the last interface with an instance number
                 * less than or equal to the new interface's instance
                 * number - except that non-loopback interfaces are
                 * arbitrarily treated as having interface numbers less
                 * than those of loopback interfaces, so the loopback
                 * interfaces are put at the end of the list.
                 *
                 * 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 a non-loopback interface
                         * and the next interface a loopback interface?
                         */
                        if (!(curdev->flags & PCAP_IF_LOOPBACK) &&
                            (nextdev->flags & PCAP_IF_LOOPBACK)) {
                                /*
                                 * Yes, we should put the new entry
                                 * before "nextdev", i.e. after "prevdev".
                                 */
                                break;
                        }

                        /*
                         * Is the new interface's instance number less
                         * than the next interface's instance number,
                         * and is it the case that the new interface is a
                         * non-loopback interface or the next interface is
                         * a loopback interface?
                         *
                         * (The goal of both loopback tests is to make
                         * sure that we never put a loopback interface
                         * before any non-loopback interface and that we
                         * always put a non-loopback interface before all
                         * loopback interfaces.)
                         */
                        if (this_instance < get_instance(nextdev->name) &&
                            (!(curdev->flags & PCAP_IF_LOOPBACK) ||
                               (nextdev->flags & PCAP_IF_LOOPBACK))) {
                                /*
                                 * 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);
}

static int
add_addr_to_iflist(pcap_if_t **alldevs, char *name, u_int flags,
    struct sockaddr *addr, struct sockaddr *netmask,
    struct sockaddr *broadaddr, struct sockaddr *dstaddr, char *errbuf)
{
        pcap_if_t *curdev;
        pcap_addr_t *curaddr, *prevaddr, *nextaddr;

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

        /*
         * "curdev" is an entry for this interface; add an entry for this
         * address to its list of addresses.
         *
         * Allocate the new entry and fill it in.
         */
        curaddr = malloc(sizeof(pcap_addr_t));
        if (curaddr == NULL) {
                (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "malloc: %s", pcap_strerror(errno));
                return (-1);
        }

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

static int
pcap_add_if(pcap_if_t **devlist, char *name, u_int flags, char *errbuf)
{
        pcap_if_t *curdev;

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

/*
 * Get a list of all interfaces that are up and that we can open.
 * Returns -1 on error, 0 otherwise.
 * The list, as returned through "alldevsp", may be null if no interfaces
 * were up and could be opened.
 */
#ifdef HAVE_IFADDRS_H
int
pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
{
        pcap_if_t *devlist = NULL;
        struct ifaddrs *ifap, *ifa;
        struct sockaddr *broadaddr, *dstaddr;
        int ret = 0;

        /*
         * Get the list of interface addresses.
         *
         * Note: this won't return information about interfaces
         * with no addresses; are there any such interfaces
         * that would be capable of receiving packets?
         * (Interfaces incapable of receiving packets aren't
         * very interesting from libpcap's point of view.)
         *
         * LAN interfaces will probably have link-layer
         * addresses; I don't know whether all implementations
         * of "getifaddrs()" now, or in the future, will return
         * those.
         */
        if (getifaddrs(&ifap) != 0) {
                (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "getifaddrs: %s", pcap_strerror(errno));
                return (-1);
        }
        for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
                /*
                 * Is this interface up?
                 */
                if (!(ifa->ifa_flags & IFF_UP)) {
                        /*
                         * No, so don't add it to the list.
                         */
                        continue;
                }

                /*
                 * "ifa_broadaddr" may be non-null even on
                 * non-broadcast interfaces; "ifa_dstaddr"
                 * was, on at least one FreeBSD 4.1 system,
                 * non-null on a non-point-to-point
                 * interface.
                 */
                if (ifa->ifa_flags & IFF_BROADCAST)
                        broadaddr = ifa->ifa_broadaddr;
                else
                        broadaddr = NULL;
                if (ifa->ifa_flags & IFF_POINTOPOINT)
                        dstaddr = ifa->ifa_dstaddr;
                else
                        dstaddr = NULL;

                /*
                 * Add information for this address to the list.
                 */
                if (add_addr_to_iflist(&devlist, ifa->ifa_name,
                    ifa->ifa_flags, ifa->ifa_addr, ifa->ifa_netmask,
                    broadaddr, dstaddr, errbuf) < 0) {
                        ret = -1;
                        break;
                }
        }

        freeifaddrs(ifap);

        if (ret != -1) {
                /*
                 * We haven't had any errors yet; add the "any" device,
                 * if we can open it.
                 */
                if (pcap_add_if(&devlist, "any", 0, errbuf) < 0)
                        ret = -1;
        }

        if (ret == -1) {
                /*
                 * We had an error; free the list we've been constructing.
                 */
                if (devlist != NULL) {
                        pcap_freealldevs(devlist);
                        devlist = NULL;
                }
        }

        *alldevsp = devlist;
        return (ret);
}
#else /* HAVE_IFADDRS_H */
#ifdef HAVE_PROC_NET_DEV
/*
 * Get from "/proc/net/dev" all interfaces listed there; if they're
 * already in the list of interfaces we have, that won't add another
 * instance, but if they're not, that'll add them.
 *
 * We don't bother getting any addresses for them; it appears you can't
 * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and,
 * although some other types of addresses can be fetched with SIOCGIFADDR,
 * we don't bother with them for now.
 *
 * We also don't fail if we couldn't open "/proc/net/dev"; we just leave
 * the list of interfaces as is.
 */
static int
scan_proc_net_dev(pcap_if_t **devlistp, int fd, char *errbuf)
{
        FILE *proc_net_f;
        char linebuf[512];
        int linenum;
        unsigned char *p;
        char name[512]; /* XXX - pick a size */
        char *q, *saveq;
        struct ifreq ifrflags;
        int ret = 0;

        proc_net_f = fopen("/proc/net/dev", "r");
        if (proc_net_f == NULL)
                return (0);

        for (linenum = 1;
            fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) {
                /*
                 * Skip the first two lines - they're headers.
                 */
                if (linenum <= 2)
                        continue;

                p = &linebuf[0];

                /*
                 * Skip leading white space.
                 */
                while (*p != '\0' && isspace(*p))
                        p++;
                if (*p == '\0' || *p == '\n')
                        continue;       /* blank line */

                /*
                 * Get the interface name.
                 */
                q = &name[0];
                while (*p != '\0' && !isspace(*p)) {
                        if (*p == ':') {
                                /*
                                 * This could be the separator between a
                                 * name and an alias number, or it could be
                                 * the separator between a name with no 
                                 * alias number and the next field.
                                 *
                                 * If there's a colon after digits, it
                                 * separates the name and the alias number,
                                 * otherwise it separates the name and the
                                 * next field.
                                 */
                                saveq = q;
                                while (isdigit(*p))
                                        *q++ = *p++;
                                if (*p != ':') {
                                        /*
                                         * That was the next field,
                                         * not the alias number.
                                         */
                                        q = saveq;
                                }
                                break;
                        } else
                                *q++ = *p++;
                }
                *q = '\0';

                /*
                 * Get the flags for this interface, and skip it if
                 * it's not up.
                 */
                strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
                if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
                        if (errno == ENXIO)
                                continue;
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "SIOCGIFFLAGS: %.*s: %s",
                            (int)sizeof(ifrflags.ifr_name),
                            ifrflags.ifr_name,
                            pcap_strerror(errno));
                        ret = -1;
                        break;
                }
                if (!(ifrflags.ifr_flags & IFF_UP))
                        continue;

                /*
                 * Add an entry for this interface, with no addresses.
                 */
                if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, errbuf) == -1) {
                        /*
                         * Failure.
                         */
                        ret = -1;
                        break;
                }
        }
        if (ret != -1) {
                /*
                 * Well, we didn't fail for any other reason; did we
                 * fail due to an error reading the file?
                 */
                if (ferror(proc_net_f)) {
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "Error reading /proc/net/dev: %s",
                            pcap_strerror(errno));
                        ret = -1;
                }
        }

        (void)fclose(proc_net_f);
        return (ret);
}
#endif /* HAVE_PROC_NET_DEV */

int
pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
{
        pcap_if_t *devlist = NULL;
        register int fd;
        register struct ifreq *ifrp, *ifend, *ifnext;
        int n;
        struct ifconf ifc;
        char *buf = NULL;
        unsigned buf_size;
        struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
        struct sockaddr *netmask, *broadaddr, *dstaddr;
        int ret = 0;

        /*
         * Create a socket from which to fetch the list of interfaces.
         */
        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0) {
                (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "socket: %s", pcap_strerror(errno));
                return (-1);
        }

        /*
         * Start with an 8K buffer, and keep growing the buffer until
         * we get the entire interface list or fail to get it for some
         * reason other than EINVAL (which is presumed here to mean
         * "buffer is too small").
         */
        buf_size = 8192;
        for (;;) {
                buf = malloc(buf_size);
                if (buf == NULL) {
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "malloc: %s", pcap_strerror(errno));
                        (void)close(fd);
                        return (-1);
                }

                ifc.ifc_len = buf_size;
                ifc.ifc_buf = buf;
                memset(buf, 0, buf_size);
                if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
                    && errno != EINVAL) {
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "SIOCGIFCONF: %s", pcap_strerror(errno));
                        (void)close(fd);
                        free(buf);
                        return (-1);
                }
                if (ifc.ifc_len < buf_size)
                        break;
                free(buf);
                buf_size *= 2;
        }

        ifrp = (struct ifreq *)buf;
        ifend = (struct ifreq *)(buf + ifc.ifc_len);

        for (; ifrp < ifend; ifrp = ifnext) {
                n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
                if (n < sizeof(*ifrp))
                        ifnext = ifrp + 1;
                else
                        ifnext = (struct ifreq *)((char *)ifrp + n);

                /*
                 * Get the flags for this interface, and skip it if it's
                 * not up.
                 */
                strncpy(ifrflags.ifr_name, ifrp->ifr_name,
                    sizeof(ifrflags.ifr_name));
                if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
                        if (errno == ENXIO)
                                continue;
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "SIOCGIFFLAGS: %.*s: %s",
                            (int)sizeof(ifrflags.ifr_name),
                            ifrflags.ifr_name,
                            pcap_strerror(errno));
                        ret = -1;
                        break;
                }
                if (!(ifrflags.ifr_flags & IFF_UP))
                        continue;

                /*
                 * Get the netmask for this address on this interface.
                 */
                strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
                    sizeof(ifrnetmask.ifr_name));
                memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
                    sizeof(ifrnetmask.ifr_addr));
                if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
                        if (errno == EADDRNOTAVAIL) {
                                /*
                                 * Not available.
                                 */
                                netmask = NULL;
                        } else {
                                (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                                    "SIOCGIFNETMASK: %.*s: %s",
                                    (int)sizeof(ifrnetmask.ifr_name),
                                    ifrnetmask.ifr_name,
                                    pcap_strerror(errno));
                                ret = -1;
                                break;
                        }
                } else
                        netmask = &ifrnetmask.ifr_addr;

                /*
                 * Get the broadcast address for this address on this
                 * interface (if any).
                 */
                if (ifrflags.ifr_flags & IFF_BROADCAST) {
                        strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
                            sizeof(ifrbroadaddr.ifr_name));
                        memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
                            sizeof(ifrbroadaddr.ifr_addr));
                        if (ioctl(fd, SIOCGIFBRDADDR,
                            (char *)&ifrbroadaddr) < 0) {
                                if (errno == EADDRNOTAVAIL) {
                                        /*
                                         * Not available.
                                         */
                                        broadaddr = NULL;
                                } else {
                                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                                            "SIOCGIFBRDADDR: %.*s: %s",
                                            (int)sizeof(ifrbroadaddr.ifr_name),
                                            ifrbroadaddr.ifr_name,
                                            pcap_strerror(errno));
                                        ret = -1;
                                        break;
                                }
                        } else
                                broadaddr = &ifrbroadaddr.ifr_broadaddr;
                } else {
                        /*
                         * Not a broadcast interface, so no broadcast
                         * address.
                         */
                        broadaddr = NULL;
                }

                /*
                 * Get the destination address for this address on this
                 * interface (if any).
                 */
                if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
                        strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
                            sizeof(ifrdstaddr.ifr_name));
                        memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
                            sizeof(ifrdstaddr.ifr_addr));
                        if (ioctl(fd, SIOCGIFDSTADDR,
                            (char *)&ifrdstaddr) < 0) {
                                if (errno == EADDRNOTAVAIL) {
                                        /*
                                         * Not available.
                                         */
                                        dstaddr = NULL;
                                } else {
                                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                                            "SIOCGIFDSTADDR: %.*s: %s",
                                            (int)sizeof(ifrdstaddr.ifr_name),
                                            ifrdstaddr.ifr_name,
                                            pcap_strerror(errno));
                                        ret = -1;
                                        break;
                                }
                        } else
                                dstaddr = &ifrdstaddr.ifr_dstaddr;
                } else
                        dstaddr = NULL;

                /*
                 * Add information for this address to the list.
                 */
                if (add_addr_to_iflist(&devlist, ifrp->ifr_name,
                    ifrflags.ifr_flags, &ifrp->ifr_addr,
                    netmask, broadaddr, dstaddr, errbuf) < 0) {
                        ret = -1;
                        break;
                }
        }
        free(buf);

#ifdef HAVE_PROC_NET_DEV
        if (ret != -1) {
                /*
                 * We haven't had any errors yet; now read "/proc/net/dev",
                 * and add to the list of interfaces all interfaces listed
                 * there that we don't already have, because, on Linux,
                 * SIOCGIFCONF reports only interfaces with IPv4 addresses,
                 * so you need to read "/proc/net/dev" to get the names of
                 * the rest of the interfaces.
                 */
                ret = scan_proc_net_dev(&devlist, fd, errbuf);
        }
#endif
        (void)close(fd);

        if (ret != -1) {
                /*
                 * We haven't had any errors yet; add the "any" device,
                 * if we can open it.
                 */
                if (pcap_add_if(&devlist, "any", 0, errbuf) < 0) {
                        /*
                         * Oops, we had a fatal error.
                         */
                        ret = -1;
                }
        }

        if (ret == -1) {
                /*
                 * We had an error; free the list we've been constructing.
                 */
                if (devlist != NULL) {
                        pcap_freealldevs(devlist);
                        devlist = NULL;
                }
        }

        *alldevsp = devlist;
        return (ret);
}
#endif /* HAVE_IFADDRS_H */

/*
 * 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);
        }
}

/*
 * 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 char *device;
        register bpf_u_int32 *netp, *maskp;
        register char *errbuf;
{
        register int fd;
        register struct sockaddr_in *sin;
        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) {
                *netp = *maskp = 0;
                return 0;
        }

        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0) {
                (void)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)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
        if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
                if (errno == EADDRNOTAVAIL) {
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "%s: no IPv4 address assigned", device);
                } else {
                        (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "SIOCGIFADDR: %s: %s",
                            device, pcap_strerror(errno));
                }
                (void)close(fd);
                return (-1);
        }
        sin = (struct sockaddr_in *)&ifr.ifr_addr;
        *netp = sin->sin_addr.s_addr;
        if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
                (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
                (void)close(fd);
                return (-1);
        }
        (void)close(fd);
        *maskp = sin->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)snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "inet class for 0x%x unknown", *netp);
                        return (-1);
                }
        }
        *netp &= *maskp;
        return (0);
}