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fad-gifc.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[] _U_ =
    "@(#) $Header$ (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;            /* Squelch compiler warnings on some platforms for */
struct rtentry;         /* declarations in <net/if.h> */
#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>

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#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, some use the RFC 2553
 * variant of the old BSD scheme (with "struct sockaddr_storage" rather
 * than "struct sockaddr"), and some use the new BSD scheme.
 *
 * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
 * macro that determines the size based on the address family.  Other
 * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
 * but not in the final version).
 *
 * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
 * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
 * address in an entry returned by SIOCGIFCONF.
 */
#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 */

/*
 * This is also fun.
 *
 * There is no ioctl that returns the amount of space required for all
 * the data that SIOCGIFCONF could return, and if a buffer is supplied
 * that's not large enough for all the data SIOCGIFCONF could return,
 * on at least some platforms it just returns the data that'd fit with
 * no indication that there wasn't enough room for all the data, much
 * less an indication of how much more room is required.
 *
 * The only way to ensure that we got all the data is to pass a buffer
 * large enough that the amount of space in the buffer *not* filled in
 * is greater than the largest possible entry.
 *
 * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
 * that no address is more than 255 bytes (on systems where the "sa_len"
 * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
 * case, and addresses are unlikely to be bigger than that in any case).
 */
#define MAX_SA_LEN      255

#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, NULL,
                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 */

/*
 * 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.
 *
 * This is the implementation used on platforms that have SIOCGIFCONF but
 * don't have any other mechanism for getting a list of interfaces.
 *
 * XXX - or platforms that have other, better mechanisms but for which
 * we don't yet have code to use that mechanism; I think there's a better
 * way on Linux, for example.
 */
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;
#if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
      char *p, *q;
#endif
      struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
      struct sockaddr *netmask, *broadaddr, *dstaddr;
      size_t netmask_size, broadaddr_size, dstaddr_size;
      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 have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
       * bytes left over in the buffer or we fail to get the
       * interface list 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 &&
                (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
                  break;
            free(buf);
            buf_size *= 2;
      }

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

      for (; ifrp < ifend; ifrp = ifnext) {
            /*
             * XXX - what if this isn't an IPv4 address?  Can
             * we still get the netmask, etc. with ioctls on
             * an IPv4 socket?
             *
             * The answer is probably platform-dependent, and
             * if the answer is "no" on more than one platform,
             * the way you work around it is probably platform-
             * dependent as well.
             */
            n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
            if (n < sizeof(*ifrp))
                  ifnext = ifrp + 1;
            else
                  ifnext = (struct ifreq *)((char *)ifrp + n);

            /*
             * XXX - The 32-bit compatibility layer for Linux on IA-64
             * is slightly broken. It correctly converts the structures
             * to and from kernel land from 64 bit to 32 bit but 
             * doesn't update ifc.ifc_len, leaving it larger than the 
             * amount really used. This means we read off the end 
             * of the buffer and encounter an interface with an 
             * "empty" name. Since this is highly unlikely to ever 
             * occur in a valid case we can just finish looking for 
             * interfaces if we see an empty name.
             */
            if (!(*ifrp->ifr_name))
                  break;

            /*
             * Skip entries that begin with "dummy".
             * XXX - what are these?  Is this Linux-specific?
             * Are there platforms on which we shouldn't do this?
             */
            if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
                  continue;

            /*
             * 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;
                        netmask_size = 0;
                  } 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;
                  netmask_size = SA_LEN(netmask);
            }

            /*
             * 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;
                              broadaddr_size = 0;
                        } 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;
                        broadaddr_size = SA_LEN(broadaddr);
                  }
            } else {
                  /*
                   * Not a broadcast interface, so no broadcast
                   * address.
                   */
                  broadaddr = NULL;
                  broadaddr_size = 0;
            }

            /*
             * 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;
                              dstaddr_size = 0;
                        } 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;
                        dstaddr_size = SA_LEN(dstaddr);
                  }
            } else {
                  /*
                   * Not a point-to-point interface, so no destination
                   * address.
                   */
                  dstaddr = NULL;
                  dstaddr_size = 0;
            }

#if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
            /*
             * If this entry has a colon followed by a number at
             * the end, it's a logical interface.  Those are just
             * the way you assign multiple IP addresses to a real
             * interface, so an entry for a logical interface should
             * be treated like the entry for the real interface;
             * we do that by stripping off the ":" and the number.
             */
            p = strchr(ifrp->ifr_name, ':');
            if (p != NULL) {
                  /*
                   * We have a ":"; is it followed by a number?
                   */
                  q = p + 1;
                  while (isdigit((unsigned char)*q))
                        q++;
                  if (*q == '\0') {
                        /*
                         * All digits after the ":" until the end.
                         * Strip off the ":" and everything after
                         * it.
                         */
                        *p = '\0';
                  }
            }
#endif

            /*
             * Add information for this address to the list.
             */
            if (add_addr_to_iflist(&devlist, ifrp->ifr_name,
                ifrflags.ifr_flags, &ifrp->ifr_addr,
                SA_LEN(&ifrp->ifr_addr), netmask, netmask_size,
                broadaddr, broadaddr_size, dstaddr, dstaddr_size,
                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; do any platform-specific
             * operations to add devices.
             */
            if (pcap_platform_finddevs(&devlist, 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);
}

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