Update.

1999-08-25  Ulrich Drepper  <drepper@cygnus.com>

	* inet/Makefile (routines): Add getipnodebynm.
	* inet/getipnodebynm.c: New file.
	* nss/digits_dots.c: If HAVE_TYPE is define type contains the
	interface type.
	* nss/nss_files/files-XXX.c: Define EXTRA_ARGS, EXTRA_ARGS_DECL, and
	EXTRA_ARGS_VALUE is not already done.
	(internal_getent): Allow extra parameters and pass them to parse_line.
	(_nss_files_get,ENTNAME_r): Pass extra parameters to internal_getent.
	(_nss_files_get##name##_r): Likewise.
	* nss/nss_files/files-hosts.c: Define EXTRA_ARGS, EXTRA_ARGS_DECL,
	and EXTRA_ARGS_VALUE to pass flags and type to parser.
	Add getipnodebyname function.
	* nss/nss_files/files-parse.c: Define EXTRA_ARGS, EXTRA_ARGS_DECL, and
	EXTRA_ARGS_VALUE is not already done.
	(parse_line): Add EXTRA_ARGS_DECL to parameter list.
	* nss/nss_db/db-XXX.c (lookup): Allow extra parameters and pass them
	to parse_line.
	(_nss_db_get##name##_r): Pass extra parameters to lookup.
	(_nss_db_get,ENTNAME_r): Likewise.
	* sysdeps/generic/if_index.c (__protocol_available): New function.
	* sysdeps/unix/sysv/linux/if_index.c: Likewise.

ChangeLog

@@ -1,3 +1,27 @@
+1999-08-25  Ulrich Drepper  <drepper@cygnus.com>
+
+	* inet/Makefile (routines): Add getipnodebynm.
+	* inet/getipnodebynm.c: New file.
+	* nss/digits_dots.c: If HAVE_TYPE is define type contains the
+	interface type.
+	* nss/nss_files/files-XXX.c: Define EXTRA_ARGS, EXTRA_ARGS_DECL, and
+	EXTRA_ARGS_VALUE is not already done.
+	(internal_getent): Allow extra parameters and pass them to parse_line.
+	(_nss_files_get,ENTNAME_r): Pass extra parameters to internal_getent.
+	(_nss_files_get##name##_r): Likewise.
+	* nss/nss_files/files-hosts.c: Define EXTRA_ARGS, EXTRA_ARGS_DECL,
+	and EXTRA_ARGS_VALUE to pass flags and type to parser.
+	Add getipnodebyname function.
+	* nss/nss_files/files-parse.c: Define EXTRA_ARGS, EXTRA_ARGS_DECL, and
+	EXTRA_ARGS_VALUE is not already done.
+	(parse_line): Add EXTRA_ARGS_DECL to parameter list.
+	* nss/nss_db/db-XXX.c (lookup): Allow extra parameters and pass them
+	to parse_line.
+	(_nss_db_get##name##_r): Pass extra parameters to lookup.
+	(_nss_db_get,ENTNAME_r): Likewise.
+	* sysdeps/generic/if_index.c (__protocol_available): New function.
+	* sysdeps/unix/sysv/linux/if_index.c: Likewise.
+
 1999-08-24  Ulrich Drepper  <drepper@cygnus.com>
 
 	* login/pty-private.h: Move to...

inet/Makefile

@@ -45,7 +45,8 @@ routines := htonl htons		\
 	    rcmd rexec ruserpass \
 	    getnetgrent_r getnetgrent \
 	    getaliasent_r getaliasent getaliasname getaliasname_r \
-	    in6_addr getnameinfo if_index getipnodebyad freehostent
+	    in6_addr getnameinfo if_index getipnodebyad freehostent \
+	    getipnodebynm
 
 tests := htontest test_ifindex tst-ntoa tst-ether_aton tst-ipnode
 

inet/getipnodebynm.c

@@ -0,0 +1,194 @@
+/* Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <string.h>
+#include <arpa/inet.h>
+
+#include "nsswitch.h"
+
+
+/* We avoid using a too large buffer in case the user is accumulating the
+   results and there is lots of unused space in the allocated buffer.  */
+#define BUFLEN	512
+
+
+/* Internal function to test whether IPv4 and/or IPv6 are available.  */
+extern void __protocol_available (int *have_inet, int *have_inet6)
+     internal_function;
+
+
+/* Type of the lookup function we need here.  */
+typedef enum nss_status (*lookup_function) (const char *, int, int,
+					    struct hostent *, char *,
+					    size_t, int *, int *);
+
+/* The lookup function for the first entry of this service.  */
+extern int __nss_hosts_lookup (service_user **nip, const char *name,
+			       void **fctp);
+
+
+struct hostent *
+getipnodebyname (const char *name, int type, int flags, int *h_errnop)
+{
+  static service_user *startp;
+  static lookup_function start_fct;
+  service_user *nip;
+  lookup_function fct;
+  int no_more;
+  size_t buffer_size;
+  char *buffer;
+  struct hostent *result;
+  int save;
+  int have_inet = 1;
+  int have_inet6 = 1;
+
+  /* First determine whether we have the appropriate interfaces.
+     XXX I don't think we can cache the result since the system
+     can be reconfigured.  */
+  if ((flags & AI_ADDRCONFIG) != 0)
+    __protocol_available (&have_inet, &have_inet6);
+
+  /* Handle impossible requests first.  */
+  if ((type == AF_INET && have_inet == 0)
+      || (type == AF_INET6 && have_inet6 == 0 && ((flags & AI_V4MAPPED) == 0
+						  || have_inet == 0))
+      || (type != AF_INET && type != AF_INET6))
+    {
+      *h_errnop = NO_DATA;
+      return NULL;
+    }
+
+  buffer_size = BUFLEN;
+  buffer = (char *) malloc (buffer_size);
+
+  result = NULL;
+  if (buffer != NULL)
+    {
+#define HAVE_TYPE
+#define resbuf (*((struct hostent *) buffer))
+#include "../nss/digits_dots.c"
+    }
+
+  if (startp == NULL)
+    {
+      no_more = __nss_hosts_lookup (&nip, "getipnodebyname_r", (void **) &fct);
+      if (no_more)
+	startp = (service_user *) -1l;
+      else
+	{
+	  startp = nip;
+	  start_fct = fct;
+	}
+    }
+  else
+    {
+      fct = start_fct;
+      no_more = (nip = startp) == (service_user *) -1l;
+    }
+
+  /* First do a lookup with the original protocol type.  */
+  while (no_more == 0 && buffer != NULL)
+    {
+      enum nss_status status;
+
+      status = DL_CALL_FCT (fct, (name, type,
+				  ((flags & AI_ALL)
+				   ? flags : (flags & ~AI_V4MAPPED)),
+				  (struct hostent *) buffer,
+				  (char *) ((struct hostent *) buffer + 1),
+				  buffer_size - sizeof (struct hostent),
+				  &errno, h_errnop));
+
+      if (status == NSS_STATUS_SUCCESS)
+	{
+	  result = (struct hostent *) buffer;
+	  break;
+	}
+
+      if (status == NSS_STATUS_TRYAGAIN && *h_errnop == NETDB_INTERNAL
+	  && errno == ERANGE)
+	{
+	  /* Resize the buffer, it's too small.  */
+	  buffer_size += BUFLEN;
+	  buffer = (char *) realloc (buffer, buffer_size);
+	  continue;
+	}
+
+      no_more = __nss_next (&nip, "getipnodebyname_r",
+			    (void **) &fct, status, 0);
+    }
+
+  /* If we are looking for an IPv6 address but haven't found any and
+     do not have the AI_ALL but the AI_V4MAPPED flag set, now try
+     looking up an IPv4 address and map it.  */
+  if (buffer != NULL && result == NULL
+      && type == AF_INET6 && (flags & AI_V4MAPPED) != 0
+      && (no_more = (nip = startp) == (service_user *) -1l) == 0)
+    {
+      /* We have to use a new buffer if there is already a result.  */
+      fct = start_fct;
+
+      do
+	{
+	  enum nss_status status;
+
+	  status = DL_CALL_FCT (fct, (name, type, flags,
+				      (struct hostent *) buffer,
+				      (char *) ((struct hostent *) buffer + 1),
+				      buffer_size - sizeof (struct hostent),
+				      &errno, h_errnop));
+
+	  if (status == NSS_STATUS_SUCCESS)
+	    {
+	      result = (struct hostent *) buffer;
+	      break;
+	    }
+
+	  if (status == NSS_STATUS_TRYAGAIN && *h_errnop == NETDB_INTERNAL
+	      && errno == ERANGE)
+	    {
+	      /* Resize the buffer, it's too small.  */
+	      buffer_size += BUFLEN;
+	      buffer = (char *) realloc (buffer, buffer_size);
+	      continue;
+	    }
+
+	  no_more = __nss_next (&nip, "getipnodebyname_r",
+				(void **) &fct, status, 0);
+	}
+      while (no_more == 0 && buffer != NULL);
+    }
+
+ done:
+  if (buffer == NULL)
+    {
+      /* We are out of memory.  */
+      *h_errnop = TRY_AGAIN;
+      assert (result == NULL);
+    }
+  else if (result == NULL && buffer != NULL)
+    free (buffer);
+
+  return result;
+}

login/programs/pt_chown.c

@@ -111,7 +111,7 @@ do_pt_chown (void)
      character device.  */
   if (stat (pty, &st) < 0
 #ifdef unix98_pseudo_p
-      || ! unix98_pseudo_p (st.st_rdev)
+      || ! unix98_pseudo_p (major (st.st_rdev))
 #else
       || !S_ISCHR(st.st_mode)
 #endif

nss/digits_dots.c

@@ -31,11 +31,12 @@
       host_addr_list_t *h_addr_ptrs;
       size_t size_needed;
       int addr_size;
-#ifndef HAVE_AF
-      int af = -1;
-#endif
 #ifdef HAVE_TYPE
       int af = type;
+#else
+# ifndef HAVE_AF
+      int af = -1;
+# endif
 #endif
 
       switch (af)
@@ -153,7 +154,7 @@
 			  /* That's bad.  The user hasn't specified that she
 			     allows IPv4 numeric addresses.  */
 			  result = NULL;
-			  *herrno_p = HOST_NOT_FOUND;
+			  *h_errnop = HOST_NOT_FOUND;
 			  goto done;
 			}
 		      else
@@ -206,11 +207,12 @@
 	  host_addr_list_t *h_addr_ptrs;
 	  size_t size_needed;
 	  int addr_size;
-#ifndef HAVE_AF
-	  int af = -1;
-#endif
 #ifdef HAVE_TYPE
 	  int af = type;
+#else
+# ifndef HAVE_AF
+	  int af = -1;
+# endif
 #endif
 
 	  switch (af)

nss/nss_db/db-XXX.c

@@ -1,5 +1,5 @@
 /* Common code for DB-based databases in nss_db module.
-   Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -162,7 +162,7 @@ CONCAT(_nss_db_end,ENTNAME) (void)
 /* Do a database lookup for KEY.  */
 static enum nss_status
 lookup (DBT *key, struct STRUCTURE *result,
-	void *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)
+	void *buffer, size_t buflen, int *errnop H_ERRNO_PROTO EXTRA_ARGS_DECL)
 {
   char *p;
   enum nss_status status;
@@ -211,7 +211,7 @@ lookup (DBT *key, struct STRUCTURE *result,
       while (isspace (*p))
 	++p;
 
-      err = parse_line (p, result, buffer, buflen, errnop);
+      err = parse_line (p, result, buffer, buflen, errnop EXTRA_ARGS);
 
       if (err == 0)
 	{
@@ -274,7 +274,8 @@ _nss_db_get##name##_r (proto,						      \
   key.size = KEYPRINTF keypattern;					      \
   key.flags = 0;							      \
   __libc_lock_lock (lock);						      \
-  status = lookup (&key, result, buffer, buflen, errnop H_ERRNO_ARG);	      \
+  status = lookup (&key, result, buffer, buflen, errnop H_ERRNO_ARG	      \
+		   EXTRA_ARGS_VALUE);					      \
   __libc_lock_unlock (lock);						      \
   return status;							      \
 }
@@ -302,7 +303,8 @@ CONCAT(_nss_db_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
     {
       key.size = snprintf (key.data = buf, sizeof buf, "0%u", entidx++);
       key.flags = 0;
-      status = lookup (&key, result, buffer, buflen, errnop H_ERRNO_ARG);
+      status = lookup (&key, result, buffer, buflen, errnop H_ERRNO_ARG
+		       EXTRA_ARGS_VALUE);
       if (status == NSS_STATUS_TRYAGAIN
 #ifdef NEED_H_ERRNO
 	  && *herrnop == NETDB_INTERNAL

nss/nss_files/files-XXX.c

@@ -50,6 +50,12 @@
 # define H_ERRNO_SET(val) ((void) 0)
 #endif
 
+#ifndef EXTRA_ARGS
+# define EXTRA_ARGS
+# define EXTRA_ARGS_DECL
+# define EXTRA_ARGS_VALUE
+#endif
+
 /* Locks the static variables in this file.  */
 __libc_lock_define_initialized (static, lock)
 
@@ -161,7 +167,8 @@ CONCAT(_nss_files_end,ENTNAME) (void)
 
 static enum nss_status
 internal_getent (struct STRUCTURE *result,
-		 char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)
+		 char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO
+		 EXTRA_ARGS_DECL)
 {
   char *p;
   struct parser_data *data = (void *) buffer;
@@ -204,7 +211,8 @@ internal_getent (struct STRUCTURE *result,
   while (*p == '\0' || *p == '#' /* Ignore empty and comment lines.  */
 	 /* Parse the line.  If it is invalid, loop to get the next
 	    line of the file to parse.  */
-	 || ! (parse_result = parse_line (p, result, data, buflen, errnop)));
+	 || ! (parse_result = parse_line (p, result, data, buflen, errnop
+					  EXTRA_ARGS)));
 
   /* Filled in RESULT with the next entry from the database file.  */
   return parse_result == -1 ? NSS_STATUS_TRYAGAIN : NSS_STATUS_SUCCESS;
@@ -249,7 +257,7 @@ CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
       if (status == NSS_STATUS_SUCCESS)
 	{
 	  status = internal_getent (result, buffer, buflen, errnop
-				    H_ERRNO_ARG);
+				    H_ERRNO_ARG EXTRA_ARGS_VALUE);
 
 	  /* Remember this position if we were successful.  If the
 	     operation failed we give the user a chance to repeat the
@@ -298,7 +306,7 @@ _nss_files_get##name##_r (proto,					      \
       last_use = getby;							      \
 									      \
       while ((status = internal_getent (result, buffer, buflen, errnop	      \
-					H_ERRNO_ARG))			      \
+					H_ERRNO_ARG EXTRA_ARGS_VALUE))	      \
 	     == NSS_STATUS_SUCCESS)					      \
 	{ break_if_match }						      \
 									      \

nss/nss_files/files-hosts.c

@@ -1,5 +1,5 @@
 /* Hosts file parser in nss_files module.
-   Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -32,6 +32,9 @@
 #define DATABASE	"hosts"
 #define NEED_H_ERRNO
 
+#define EXTRA_ARGS	 , af, flags
+#define EXTRA_ARGS_DECL	 , int af, int flags
+
 #define ENTDATA hostent_data
 struct hostent_data
   {
@@ -50,9 +53,9 @@ LINE_PARSER
    STRING_FIELD (addr, isspace, 1);
 
    /* Parse address.  */
-   if (inet_pton (AF_INET, addr, entdata->host_addr) > 0)
+   if (af == AF_INET && inet_pton (AF_INET, addr, entdata->host_addr) > 0)
      {
-       if (_res.options & RES_USE_INET6)
+       if (flags & AI_V4MAPPED)
 	 {
 	   map_v4v6_address ((char *) entdata->host_addr,
 			     (char *) entdata->host_addr);
@@ -65,7 +68,8 @@ LINE_PARSER
 	   result->h_length = INADDRSZ;
 	 }
      }
-   else if (inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
+   else if (af == AF_INET6
+	    && inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
      {
        result->h_addrtype = AF_INET6;
        result->h_length = IN6ADDRSZ;
@@ -82,26 +86,35 @@ LINE_PARSER
    STRING_FIELD (result->h_name, isspace, 1);
  })
 
+#define EXTRA_ARGS_VALUE \
+  , ((_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET),		      \
+  ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0)
 #include "files-XXX.c"
 
 DB_LOOKUP (hostbyname, ,,
 	   {
-	     if (result->h_addrtype != ((_res.options & RES_USE_INET6)
-					? AF_INET6 : AF_INET))
-	       continue;
 	     LOOKUP_NAME_CASE (h_name, h_aliases)
 	   }, const char *name)
 
+#undef EXTRA_ARGS_VALUE
+#define EXTRA_ARGS_VALUE \
+  , af, ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0)
 DB_LOOKUP (hostbyname2, ,,
 	   {
-	     if (result->h_addrtype != af)
-	       continue;
 	     LOOKUP_NAME_CASE (h_name, h_aliases)
 	   }, const char *name, int af)
 
 DB_LOOKUP (hostbyaddr, ,,
 	   {
-	     if (result->h_addrtype == type && result->h_length == len &&
+	     if (result->h_length == len
-		 ! memcmp (addr, result->h_addr_list[0], len))
+		 && ! memcmp (addr, result->h_addr_list[0], len))
 	       break;
-	   }, const char *addr, int len, int type)
+	   }, const char *addr, int len, int af)
+
+#undef EXTRA_ARGS_VALUE
+#define EXTRA_ARGS_VALUE \
+  , af, flags
+DB_LOOKUP (ipnodebyname, ,,
+	   {
+	     LOOKUP_NAME_CASE (h_name, h_aliases)
+	   }, const char *name, int af, int flags)

nss/nss_files/files-parse.c

@@ -1,5 +1,5 @@
 /* Common code for file-based database parsers in nss_files module.
-   Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -33,8 +33,18 @@
 
    NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
 
+   EXTRA_ARGS -- defined iff extra parameters must be passed to the parser
+   EXTRA_ARGS_DECL -- declaration for these extra parameters
+   EXTRA_ARGS_VALUE -- values to be passed for these parameters
+
    Also see files-XXX.c.  */
 
+#ifndef EXTRA_ARGS
+# define EXTRA_ARGS
+# define EXTRA_ARGS_DECL
+# define EXTRA_ARGS_VALUE
+#endif
+
 #define CONCAT(a,b) CONCAT1(a,b)
 #define CONCAT1(a,b) a##b
 
@@ -69,7 +79,8 @@ struct parser_data
 
 /* The parser is defined in a different module.  */
 extern int parse_line (char *line, struct STRUCTURE *result,
-		       struct parser_data *data, size_t datalen, int *errnop);
+		       struct parser_data *data, size_t datalen, int *errnop
+		       EXTRA_ARGS_DECL);
 
 # define LINE_PARSER(EOLSET, BODY) /* Do nothing */
 
@@ -80,7 +91,8 @@ extern int parse_line (char *line, struct STRUCTURE *result,
 # define LINE_PARSER(EOLSET, BODY)					      \
 parser_stclass int							      \
 parse_line (char *line, struct STRUCTURE *result,			      \
-	    struct parser_data *data, size_t datalen, int *errnop)	      \
+	    struct parser_data *data, size_t datalen, int *errnop	      \
+	    EXTRA_ARGS_DECL)						      \
 {									      \
   ENTDATA_DECL (data)							      \
   char *p = strpbrk (line, EOLSET "\n");				      \

sysdeps/generic/if_index.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 1997, 1998 Free Software Foundation, Inc.
+/* Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -51,3 +51,13 @@ if_nameindex (void)
 }
 stub_warning (if_nameindex)
 #include <stub-tag.h>
+
+
+void
+internal_function
+__protocol_avaliable (int *have_inet, have_inet6)
+{
+  /* By default we assume that IPv4 is avaialble, IPv6 not.  */
+  *have_inet = 1;
+  *have_inet6 = 0;
+}

sysdeps/unix/sysv/linux/if_index.c

@@ -54,9 +54,9 @@ opensock (void)
 
   if (fd == -1)
     {
-      fd = __socket (sock_af = AF_INET6, SOCK_DGRAM, 0);
-      if (fd < 0)
       fd = __socket (sock_af = AF_INET, SOCK_DGRAM, 0);
+      if (fd < 0)
+	fd = __socket (sock_af = AF_INET6, SOCK_DGRAM, 0);
       if (fd < 0)
 	fd = __socket (sock_af = AF_IPX, SOCK_DGRAM, 0);
       if (fd < 0)
@@ -277,3 +277,82 @@ if_indextoname (unsigned int ifindex, char *ifname)
 # endif
 #endif
 }
+
+
+void
+internal_function
+__protocol_avaliable (int *have_inet, int *have_inet6)
+{
+  int fd = opensock ();
+  unsigned int nifs;
+  int rq_len;
+  struct ifconf ifc;
+# if __ASSUME_SIOCGIFNAME == 0
+  static int old_siocgifconf;
+# else
+#  define old_siocgifconf 0
+# endif
+# define RQ_IFS	4
+
+  /* Wirst case assumption.  */
+  *have_inet = 0;
+  *have_inet6 = 0;
+
+  if (fd == NULL)
+    /* We cannot open the socket.  No networking at all?  */
+    return;
+
+  /* We may be able to get the needed buffer size directly, rather than
+     guessing.  */
+  if (! old_siocgifconf)
+    {
+      ifc.ifc_buf = NULL;
+      ifc.ifc_len = 0;
+      if (__ioctl (fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0)
+	{
+# if __ASSUME_SIOCGIFNAME == 0
+	  old_siocgifconf = 1;
+# endif
+	  rq_len = RQ_IFS * sizeof (struct ifreq);
+	}
+      else
+	rq_len = ifc.ifc_len;
+    }
+  else
+    rq_len = RQ_IFS * sizeof (struct ifreq);
+
+  /* Read all the interfaces out of the kernel.  */
+  do
+    {
+      ifc.ifc_buf = alloca (ifc.ifc_len = rq_len);
+      if (ifc.ifc_buf == NULL || __ioctl (fd, SIOCGIFCONF, &ifc) < 0)
+	{
+	  __close (fd);
+	  return;
+	}
+      rq_len *= 2;
+    }
+  while (ifc.ifc_len == rq_len && old_siocgifconf);
+
+  nifs = ifc.ifc_len / sizeof (struct ifreq);
+
+  /* Go through all the interfaces and get the address.  */
+  while (nifs-- > 0)
+    if (__ioctl (fd, SIOCGIFADDR, &ifc.ifc_req[nifs]) >= 0)
+      {
+	/* We successfully got information about this interface.  Now
+	   test whether it is an IPv4 or IPv6 address.  */
+	if (ifc.ifc_req[nifs].ifr_addr.sa_family == AF_INET)
+	  *have_inet = 1;
+	else if (ifc.ifc_req[nifs].ifr_addr.sa_family == AF_INET6)
+	  *have_inet6 = 1;
+
+	/* Note, this is & not &&.  It works since the values are always
+	   0 or 1.  */
+	if (*have_inet & *have_inet6)
+	  /* We can stop early.  */
+	  break;
+      }
+
+  __close (fd);
+}