[libpcap] / fad-helpers.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

#ifndef _WIN32
/* 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

/*
 * Map UN*X-style interface flags to libpcap flags.
 */
bpf_u_int32
if_flags_to_pcap_flags(const char *name _U_, u_int if_flags)
{
        bpf_u_int32 pcap_flags;

        pcap_flags = 0;
        if (ISLOOPBACK(name, if_flags))
                pcap_flags |= PCAP_IF_LOOPBACK;
        if (ISUP(if_flags))
                pcap_flags |= PCAP_IF_UP;
        if (ISRUNNING(if_flags))
                pcap_flags |= PCAP_IF_RUNNING;
        return (pcap_flags);
}
#endif

static 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 an instance number.  Add 1 to the
                 * instance number, and use 0 for "no instance
                 * number", so we don't put "no instance number"
                 * devices and "instance 0" devices together.
                 */
                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) + 1;
                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);
}

#ifndef _WIN32
/*
 * 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) {
                        /*
                         * Description is empty, so discard it.
                         */
                        free(description);
                        description = NULL;
                }
        }

#ifdef __FreeBSD__
        /*
         * For FreeBSD, if we didn't get a description, and this is
         * a device with a name of the form usbusN, label it as a USB
         * bus.
         */
        if (description == NULL) {
                if (strncmp(name, "usbus", 5) == 0) {
                        /*
                         * OK, it begins with "usbus".
                         */
                        long busnum;
                        char *p;

                        errno = 0;
                        busnum = strtol(name + 5, &p, 10);
                        if (errno == 0 && p != name + 5 && *p == '\0' &&
                            busnum >= 0 && busnum <= INT_MAX) {
                                /*
                                 * OK, it's a valid number that's not
                                 * bigger than INT_MAX.  Construct
                                 * a description from it.
                                 */
                                static const char descr_prefix[] = "USB bus number ";
                                size_t descr_size;

                                /*
                                 * Allow enough room for a 32-bit bus number.
                                 * sizeof (descr_prefix) includes the
                                 * terminating NUL.
                                 */
                                descr_size = sizeof (descr_prefix) + 10;
                                description = malloc(descr_size);
                                if (description != NULL) {
                                        pcap_snprintf(description, descr_size,
                                            "%s%ld", descr_prefix, busnum);
                                }
                        }
                }
        }
#endif
        return (description);
#else /* SIOCGIFDESCR */
        return (NULL);
#endif /* SIOCGIFDESCR */
}

/*
 * Look for a given 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, attempt to add an entry for it, with the specified
 * flags and description, and, if that succeeds, add the specified
 * address to its list of addresses if that address is non-null, and
 * return 0, otherwise return -1 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, bpf_u_int32 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)
{
        pcap_if_t *curdev;

        /*
         * Attempt to find an entry for this device; if we don't find one,
         * attempt to add one.
         */
        curdev = find_or_add_dev(alldevs, name, flags, get_if_description(name),
            errbuf);
        if (curdev == NULL) {
                /*
                 * Error - give up.
                 */
                return (-1);
        }

        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));
}
#endif /* _WIN32 */

/*
 * 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 and set *curdev_ret to point to it.
 *
 * If we don't find it, attempt to add an entry for it, with the specified
 * flags and description, and, if that succeeds, return 0, otherwise
 * return -1 and set errbuf to an error message.
 */
pcap_if_t *
find_or_add_dev(pcap_if_t **alldevs, const char *name, bpf_u_int32 flags,
    const char *description, char *errbuf)
{
        pcap_if_t *curdev;

        /*
         * Is there already an entry in the list for this interface?
         */
        curdev = find_dev(alldevs, name);
        if (curdev != NULL) {
                /*
                 * Yes, return it.
                 */
                return (curdev);
        }

        /*
         * No, we didn't find it.  Try to add it to the list of devices.
         */
        return (add_dev(alldevs, name, flags, description, errbuf));
}

/*
 * Look for a given device in the specified list of devices, and return
 * the entry for it if we find it or NULL if we don't.
 */
pcap_if_t *
find_dev(pcap_if_t **alldevs, const char *name)
{
        pcap_if_t *curdev;

        /*
         * Is there an entry in the list for this device?
         */
        for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) {
                if (strcmp(name, curdev->name) == 0) {
                        /*
                         * We found it, so, yes, there is.  No need to
                         * add it.  Provide the entry we found to our
                         * caller.
                         */
                        return (curdev);
                }
        }

        /*
         * No.
         */
        return (NULL);
}

/*
 * Attempt to add an entry for a device, with the specified flags
 * and description, and, if that succeeds, return 0 and return a pointer
 * to the new entry, otherwise return NULL and set errbuf to an error
 * message.
 *
 * If we weren't given a description, try to get one.
 */
pcap_if_t *
add_dev(pcap_if_t **alldevs, const char *name, bpf_u_int32 flags,
    const char *description, char *errbuf)
{
        pcap_if_t *curdev, *prevdev, *nextdev;
        u_int this_figure_of_merit, nextdev_figure_of_merit;

        curdev = malloc(sizeof(pcap_if_t));
        if (curdev == NULL) {
                (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "malloc: %s", pcap_strerror(errno));
                return (NULL);
        }

        /*
         * 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 (NULL);
        }
        if (description == NULL) {
                /*
                 * We weren't handed a description for the interface.
                 */
                curdev->description = NULL;
        } else {
                /*
                 * We were handed a description; make a copy.
                 */
                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 (NULL);
                }
        }
        curdev->addresses = NULL;       /* list starts out as empty */
        curdev->flags = flags;

        /*
         * 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;
        return (curdev);
}

/*
 * 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);
        }
}