Add Windows version info resource.
[obnox/wireshark/wip.git] / util.c
diff --git a/util.c b/util.c
index e7f23accec91cf7cfcd1fd6b0632333eaf4f9c3d..36a579305e3c00d079edab4635d22494cdc51724 100644 (file)
--- a/util.c
+++ b/util.c
@@ -1,23 +1,22 @@
 /* util.c
  * Utility routines
  *
- * $Id: util.c,v 1.51 2001/04/02 09:53:43 guy Exp $
+ * $Id$
  *
- * Ethereal - Network traffic analyzer
- * By Gerald Combs <gerald@zing.org>
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
  * Copyright 1998 Gerald Combs
  *
- * 
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
  * of the License, or (at your option) any later version.
- * 
+ *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #include <unistd.h>
 #endif
 
-#ifdef HAVE_SYS_TYPES_H
-#include <sys/types.h>
-#endif
-
-#ifdef HAVE_SYS_STAT_H
-#include <sys/stat.h>
-#endif
-
-#ifdef NEED_SNPRINTF_H
-# include "snprintf.h"
-#endif
-
-#ifndef WIN32
-#include <pwd.h>
-#endif
-
-#ifdef NEED_MKSTEMP
-#include "mkstemp.h"
-#endif
+#include <epan/address.h>
+#include <epan/addr_resolv.h>
 
 #include "util.h"
 
-#ifdef HAVE_IO_H
-#include <io.h>
-typedef int mode_t;    /* for win32 */
-#endif
-
-#ifdef HAVE_LIBPCAP
-
-#ifdef HAVE_SYS_SOCKET_H
-#include <sys/socket.h>
-#endif
-
-#ifdef HAVE_SYS_IOCTL_H
-#include <sys/ioctl.h>
-#endif
-
-#include <pcap.h>
-
-#ifndef WIN32
-#include <net/if.h>
-#endif
-
-#ifdef HAVE_SYS_SOCKIO_H
-# include <sys/sockio.h>
-#endif
-
-#include "globals.h"
-
-#endif
-
-/*
- * Given a pathname, return:
- *
- *     the errno, if an attempt to "stat()" the file fails;
- *
- *     EISDIR, if the attempt succeeded and the file turned out
- *     to be a directory;
- *
- *     0, if the attempt succeeded and the file turned out not
- *     to be a directory.
- */
-
-/*
- * Visual C++ on Win32 systems doesn't define these.  (Old UNIX systems don't
- * define them either.)
- *
- * Visual C++ on Win32 systems doesn't define S_IFIFO, it defines _S_IFIFO.
- */
-#ifndef S_ISREG
-#define S_ISREG(mode)   (((mode) & S_IFMT) == S_IFREG)
-#endif
-#ifndef S_IFIFO
-#define S_IFIFO        _S_IFIFO
-#endif
-#ifndef S_ISFIFO
-#define S_ISFIFO(mode)  (((mode) & S_IFMT) == S_IFIFO)
-#endif
-#ifndef S_ISDIR
-#define S_ISDIR(mode)   (((mode) & S_IFMT) == S_IFDIR)
-#endif
-
-int
-test_for_directory(const char *path)
-{
-       struct stat statb;
-
-       if (stat(path, &statb) < 0)
-               return errno;
-
-       if (S_ISDIR(statb.st_mode))
-               return EISDIR;
-       else
-               return 0;
-}
-
 /*
  * Collect command-line arguments as a string consisting of the arguments,
  * separated by spaces.
@@ -174,489 +82,6 @@ get_args_as_string(int argc, char **argv, int optind)
        return argstring;
 }
 
-static char *
-setup_tmpdir(char *dir)
-{
-       int len = strlen(dir);
-       char *newdir;
-
-       /* Append slash if necessary */
-       if (dir[len - 1] == '/') {
-               newdir = dir;
-       }
-       else {
-               newdir = g_malloc(len + 2);
-               strcpy(newdir, dir);
-               strcat(newdir, "/");
-       }
-       return newdir;
-}
-
-static int
-try_tempfile(char *namebuf, int namebuflen, const char *dir, const char *pfx)
-{
-       static const char suffix[] = "XXXXXXXXXX";
-       int namelen = strlen(dir) + strlen(pfx) + sizeof suffix;
-       mode_t old_umask;
-       int tmp_fd;
-
-       if (namebuflen < namelen) {
-               /* Stick in a truncated name, so that if this error is
-                  reported with the file name, you at least get
-                  something. */
-               snprintf(namebuf, namebuflen, "%s%s%s", dir, pfx, suffix);
-               errno = ENAMETOOLONG;
-               return -1;
-       }
-       strcpy(namebuf, dir);
-       strcat(namebuf, pfx);
-       strcat(namebuf, suffix);
-
-       /* The Single UNIX Specification doesn't say that "mkstemp()"
-          creates the temporary file with mode rw-------, so we
-          won't assume that all UNIXes will do so; instead, we set
-          the umask to 0077 to take away all group and other
-          permissions, attempt to create the file, and then put
-          the umask back. */
-       old_umask = umask(0077);
-       tmp_fd = mkstemp(namebuf);
-       umask(old_umask);
-       return tmp_fd;
-}
-
-static char *tmpdir = NULL;
-#ifdef WIN32
-static char *temp = NULL;
-#endif
-static char *E_tmpdir;
-
-#ifndef P_tmpdir
-#define P_tmpdir "/var/tmp"
-#endif
-
-int
-create_tempfile(char *namebuf, int namebuflen, const char *pfx)
-{
-       char *dir;
-       int fd;
-       static gboolean initialized;
-
-       if (!initialized) {
-               if ((dir = getenv("TMPDIR")) != NULL)
-                       tmpdir = setup_tmpdir(dir);
-#ifdef WIN32
-               if ((dir = getenv("TEMP")) != NULL)
-                       temp = setup_tmpdir(dir);
-#endif
-
-               E_tmpdir = setup_tmpdir(P_tmpdir);
-               initialized = TRUE;
-       }
-
-       if (tmpdir != NULL) {
-               fd = try_tempfile(namebuf, namebuflen, tmpdir, pfx);
-               if (fd != -1)
-                       return fd;
-       }
-
-#ifdef WIN32
-       if (temp != NULL) {
-               fd = try_tempfile(namebuf, namebuflen, temp, pfx);
-               if (fd != -1)
-                       return fd;
-       }
-#endif
-
-       fd = try_tempfile(namebuf, namebuflen, E_tmpdir, pfx);
-       if (fd != -1)
-               return fd;
-
-       return try_tempfile(namebuf, namebuflen, "/tmp", pfx);
-}
-
-/* ASCII/EBCDIC conversion tables from
- * http://www.room42.com/store/computer_center/code_tables.shtml
- */
-static guint8 ASCII_translate_EBCDIC [ 256 ] = {
-    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
-    0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
-    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
-    0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
-    0x40, 0x5A, 0x7F, 0x7B, 0x5B, 0x6C, 0x50, 0x7D, 0x4D,
-    0x5D, 0x5C, 0x4E, 0x6B, 0x60, 0x4B, 0x61,
-    0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
-    0xF9, 0x7A, 0x5E, 0x4C, 0x7E, 0x6E, 0x6F,
-    0x7C, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8,
-    0xC9, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6,
-    0xD7, 0xD8, 0xD9, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7,
-    0xE8, 0xE9, 0xAD, 0xE0, 0xBD, 0x5F, 0x6D,
-    0x7D, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88,
-    0x89, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96,
-    0x97, 0x98, 0x99, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7,
-    0xA8, 0xA9, 0xC0, 0x6A, 0xD0, 0xA1, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B,
-    0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B
-};
-
-void
-ASCII_to_EBCDIC(guint8 *buf, guint bytes)
-{
-       guint   i;
-       guint8  *bufptr;
-
-       bufptr = buf;
-
-       for (i = 0; i < bytes; i++, bufptr++) {
-               *bufptr = ASCII_translate_EBCDIC[*bufptr];
-       }
-}
-
-guint8
-ASCII_to_EBCDIC1(guint8 c)
-{
-       return ASCII_translate_EBCDIC[c];
-}
-
-static guint8 EBCDIC_translate_ASCII [ 256 ] = {
-    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
-    0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
-    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
-    0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
-    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
-    0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
-    0x2E, 0x2E, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
-    0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x2E, 0x3F,
-    0x20, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x2E, 0x2E, 0x3C, 0x28, 0x2B, 0x7C,
-    0x26, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x21, 0x24, 0x2A, 0x29, 0x3B, 0x5E,
-    0x2D, 0x2F, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x7C, 0x2C, 0x25, 0x5F, 0x3E, 0x3F,
-    0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x3A, 0x23, 0x40, 0x27, 0x3D, 0x22,
-    0x2E, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
-    0x69, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71,
-    0x72, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x7E, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
-    0x7A, 0x2E, 0x2E, 0x2E, 0x5B, 0x2E, 0x2E,
-    0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x2E, 0x2E, 0x2E, 0x2E, 0x5D, 0x2E, 0x2E,
-    0x7B, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
-    0x49, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x7D, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51,                                             
-    0x52, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x5C, 0x2E, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
-    0x5A, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E,
-    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,                 
-    0x39, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E, 0x2E
-};
-
-void
-EBCDIC_to_ASCII(guint8 *buf, guint bytes)
-{
-       guint   i;
-       guint8  *bufptr;
-
-       bufptr = buf;
-
-       for (i = 0; i < bytes; i++, bufptr++) {
-               *bufptr = EBCDIC_translate_ASCII[*bufptr];
-       }
-}
-
-guint8
-EBCDIC_to_ASCII1(guint8 c)
-{
-       return EBCDIC_translate_ASCII[c];
-}
-
-#ifdef HAVE_LIBPCAP
-
-/*
- * If the ability to capture packets is added to Wiretap, these
- * routines should be moved to the Wiretap source (with
- * "get_interface_list()" and "free_interface_list()" renamed to
- * "wtap_get_interface_list()" and "wtap_free_interface_list()",
- * and modified to use Wiretap routines to attempt to open the
- * interface.
- */
-
-struct search_user_data {
-       char    *name;
-       int     found;
-};
-
-static void
-search_for_if_cb(gpointer data, gpointer user_data);
-
-static void
-free_if_cb(gpointer data, gpointer user_data);
-
-#ifndef WIN32
-GList *
-get_interface_list(int *err, char *err_str)
-{
-       GList  *il = NULL;
-       gint    nonloopback_pos = 0;
-       struct  ifreq *ifr, *last;
-       struct  ifconf ifc;
-       struct  ifreq ifrflags;
-       int     sock = socket(AF_INET, SOCK_DGRAM, 0);
-       struct search_user_data user_data;
-       pcap_t *pch;
-       int len, lastlen;
-       char *buf;
-
-       if (sock < 0) {
-               sprintf(err_str, "Error opening socket: %s",
-                   strerror(errno));
-               return NULL;
-       }
-
-       /*
-        * This code came from: W. Richard Stevens: "UNIX Network Programming",
-        * Networking APIs: Sockets and XTI, Vol 1, page 434.
-        */
-       lastlen = 0;
-       len = 100 * sizeof(struct ifreq);
-       for ( ; ; ) {
-               buf = g_malloc(len);
-               ifc.ifc_len = len;
-               ifc.ifc_buf = buf;
-               memset (buf, 0, len);
-               if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
-                       if (errno != EINVAL || lastlen != 0) {
-                               sprintf(err_str,
-                                       "SIOCGIFCONF ioctl error getting list of interfaces: %s",
-                                       strerror(errno));
-                               goto fail;
-                       }
-               } else {
-                       if (ifc.ifc_len < sizeof(struct ifreq)) {
-                               sprintf(err_str,
-                                       "SIOCGIFCONF ioctl gave too small return buffer");
-                               goto fail;
-                       }
-                       if (ifc.ifc_len == lastlen)
-                               break;                  /* success, len has not changed */
-                       lastlen = ifc.ifc_len;
-               }
-               len += 10 * sizeof(struct ifreq);       /* increment */
-               g_free(buf);
-       }
-       ifr = (struct ifreq *) ifc.ifc_req;
-       last = (struct ifreq *) ((char *) ifr + ifc.ifc_len);
-       while (ifr < last) {
-               /*
-                * Skip addresses that begin with "dummy", or that include
-                * a ":" (the latter are Solaris virtuals).
-                */
-               if (strncmp(ifr->ifr_name, "dummy", 5) == 0 ||
-                   strchr(ifr->ifr_name, ':') != NULL)
-                       goto next;
-
-               /*
-                * If we already have this interface name on the list,
-                * don't add it (SIOCGIFCONF returns, at least on
-                * BSD-flavored systems, one entry per interface *address*;
-                * if an interface has multiple addresses, we get multiple
-                * entries for it).
-                */
-               user_data.name = ifr->ifr_name;
-               user_data.found = FALSE;
-               g_list_foreach(il, search_for_if_cb, &user_data);
-               if (user_data.found)
-                       goto next;
-
-               /*
-                * Get the interface flags.
-                */
-               memset(&ifrflags, 0, sizeof ifrflags);
-               strncpy(ifrflags.ifr_name, ifr->ifr_name,
-                   sizeof ifrflags.ifr_name);
-               if (ioctl(sock, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
-                       if (errno == ENXIO)
-                               goto next;
-                       sprintf(err_str, "SIOCGIFFLAGS error getting flags for interface %s: %s",
-                           ifr->ifr_name, strerror(errno));
-                       goto fail;
-               }
-
-               /*
-                * Skip interfaces that aren't up.
-                */
-               if (!(ifrflags.ifr_flags & IFF_UP))
-                       goto next;
-
-               /*
-                * Skip interfaces that we can't open with "libpcap".
-                * Open with the minimum packet size - it appears that the
-                * IRIX SIOCSNOOPLEN "ioctl" may fail if the capture length
-                * supplied is too large, rather than just truncating it.
-                */
-               pch = pcap_open_live(ifr->ifr_name, MIN_PACKET_SIZE, 0, 0,
-                   err_str);
-               if (pch == NULL)
-                       goto next;
-               pcap_close(pch);
-
-               /*
-                * If it's a loopback interface, add it at the end of the
-                * list, otherwise add it after the last non-loopback
-                * interface, so all loopback interfaces go at the end - we
-                * don't want a loopback interface to be the default capture
-                * device unless there are no non-loopback devices.
-                */
-               if ((ifrflags.ifr_flags & IFF_LOOPBACK) ||
-                   strncmp(ifr->ifr_name, "lo", 2) == 0)
-                       il = g_list_insert(il, g_strdup(ifr->ifr_name), -1);
-               else {
-                       il = g_list_insert(il, g_strdup(ifr->ifr_name),
-                           nonloopback_pos);
-                       /*
-                        * Insert the next non-loopback interface after this
-                        * one.
-                        */
-                       nonloopback_pos++;
-               }
-
-       next:
-#ifdef HAVE_SA_LEN
-               ifr = (struct ifreq *) ((char *) ifr + ifr->ifr_addr.sa_len + IFNAMSIZ);
-#else
-               ifr = (struct ifreq *) ((char *) ifr + sizeof(struct ifreq));
-#endif
-       }
-
-#ifdef linux
-       /*
-        * OK, maybe we have support for the "any" device, to do a cooked
-        * capture on all interfaces at once.
-        * Try opening it and, if that succeeds, add it to the end of
-        * the list of interfaces.
-        */
-       pch = pcap_open_live("any", MIN_PACKET_SIZE, 0, 0, err_str);
-       if (pch != NULL) {
-               /*
-                * It worked; we can use the "any" device.
-                */
-               il = g_list_insert(il, g_strdup("any"), -1);
-               pcap_close(pch);
-       }
-#endif
-
-       g_free(ifc.ifc_buf);
-       close(sock);
-
-       if (il == NULL) {
-               /*
-                * No interfaces found.
-                */
-               *err = NO_INTERFACES_FOUND;
-       }
-       return il;
-
-fail:
-       if (il != NULL) {
-               g_list_foreach(il, free_if_cb, NULL);
-               g_list_free(il);
-       }
-       g_free(ifc.ifc_buf);
-       close(sock);
-       *err = CANT_GET_INTERFACE_LIST;
-       return NULL;
-}
-
-static void
-search_for_if_cb(gpointer data, gpointer user_data)
-{
-       struct search_user_data *search_user_data = user_data;
-
-       if (strcmp((char *)data, search_user_data->name) == 0)
-               search_user_data->found = TRUE;
-}
-#else
-GList *
-get_interface_list(int *err, char *err_str) {
-  GList  *il = NULL;
-  wchar_t *names;
-  char *win95names; 
-  char newname[255];
-  int i, j, done;
-  
-  names = (wchar_t *)pcap_lookupdev(err_str);
-  i = done = 0;
-
-  if (names) {
-         if (names[0]<256) { 
-                 /* If names[0] is less than 256 it means the first byte is 0
-                    This implies that we are using unicode characters */
-                 do 
-                 { 
-                         j = 0; 
-                         while (names[i] != 0) 
-                                 newname[j++] = names[i++]; 
-                         i++; 
-                         if (names[i] == 0) 
-                                 done = 1; 
-                         newname[j++] = 0; 
-                         il = g_list_append(il, g_strdup(newname)); 
-                 } while (!done); 
-         } 
-         else { 
-                 /* Otherwise we are in Windows 95/98 and using ascii(8 bit)
-                    characters */
-                 do 
-                 { 
-                         win95names=(char *)names; 
-                         j = 0; 
-                         while (win95names[i] != 0) 
-                                 newname[j++] = win95names[i++]; 
-                         i++; 
-                         if (win95names[i] == 0) 
-                                 done = 1; 
-                         newname[j++] = 0; 
-                         il = g_list_append(il, g_strdup(newname)); 
-                 } while (!done); 
-         } 
-  }
-  return(il);
-}
-#endif
-
-static void
-free_if_cb(gpointer data, gpointer user_data)
-{
-       g_free(data);
-}
-
-void
-free_interface_list(GList *if_list)
-{
-       while (if_list != NULL) {
-               g_free(if_list->data);
-               if_list = g_list_remove_link(if_list, if_list);
-       }
-}
-
-#endif /* HAVE_LIBPCAP */
-
-
 /* Compute the difference between two seconds/microseconds time stamps. */
 void
 compute_timestamp_diff(gint *diffsec, gint *diffusec,
@@ -700,3 +125,70 @@ compute_timestamp_diff(gint *diffsec, gint *diffusec,
     }
   }
 }
+
+/* Try to figure out if we're remotely connected, e.g. via ssh or
+   Terminal Server, and create a capture filter that matches aspects of the
+   connection.  We match the following environment variables:
+
+   SSH_CONNECTION (ssh): <remote IP> <remote port> <local IP> <local port>
+   SSH_CLIENT (ssh): <remote IP> <remote port> <local port>
+   REMOTEHOST (tcsh, others?): <remote name>
+   DISPLAY (x11): [remote name]:<display num>
+   SESSIONNAME (terminal server): <remote name>
+ */
+
+const gchar *get_conn_cfilter(void) {
+       static GString *filter_str = NULL;
+       gchar *env, **tokens;
+
+       if (filter_str == NULL) {
+               filter_str = g_string_new("");
+       }
+       if ((env = getenv("SSH_CONNECTION")) != NULL) {
+               tokens = g_strsplit(env, " ", 4);
+               if (tokens[3]) {
+                       g_string_sprintf(filter_str, "not (tcp port %s and %s host %s "
+                                                        "and tcp port %s and %s host %s)", tokens[1], host_ip_af(tokens[0]), tokens[0],
+                               tokens[3], host_ip_af(tokens[2]), tokens[2]);
+                       return filter_str->str;
+               }
+       } else if ((env = getenv("SSH_CLIENT")) != NULL) {
+               tokens = g_strsplit(env, " ", 3);
+               g_string_sprintf(filter_str, "not (tcp port %s and %s host %s "
+                       "and tcp port %s)", tokens[1], host_ip_af(tokens[0]), tokens[0], tokens[2]);
+               return filter_str->str;
+       } else if ((env = getenv("REMOTEHOST")) != NULL) {
+               if (strcasecmp(env, "localhost") == 0 || strcmp(env, "127.0.0.1") == 0) {
+                       return "";
+               }
+               g_string_sprintf(filter_str, "not %s host %s", host_ip_af(env), env);
+               return filter_str->str;
+       } else if ((env = getenv("DISPLAY")) != NULL) {
+               tokens = g_strsplit(env, ":", 2);
+               if (tokens[0] && tokens[0][0] != 0) {
+                       if (strcasecmp(tokens[0], "localhost") == 0 ||
+                                       strcmp(tokens[0], "127.0.0.1") == 0) {
+                               return "";
+                       }
+                       g_string_sprintf(filter_str, "not %s host %s",
+                               host_ip_af(tokens[0]), tokens[0]);
+                       return filter_str->str;
+               }
+       } else if ((env = getenv("SESSIONNAME")) != NULL) {
+        /* Apparently the KB article at
+         * http://technet2.microsoft.com/WindowsServer/en/library/6caf87bf-3d70-4801-9485-87e9ec3df0171033.mspx?mfr=true
+         * is incorrect.  There are _plenty_ of cases where CLIENTNAME
+         * and SESSIONNAME are set outside of a Terminal Terver session.
+         * It looks like Terminal Server sets SESSIONNAME to RDP-TCP#<number>
+         * for "real" sessions.
+         *
+         * XXX - There's a better way to do this described at
+         * http://www.microsoft.com/technet/archive/termsrv/maintain/featusability/tsrvapi.mspx?mfr=true
+         */
+               if (g_strncasecmp(env, "rdp", 3) == 0) {
+                       g_string_sprintf(filter_str, "not tcp port 3389");
+                       return filter_str->str;
+               }
+       }
+       return "";
+}