[PATCH 14/31] ipv6: check for support in system and in adns

[Ian Jackson]

We #define CONFIG_IPV6 if the system has AF_INET6 and adns has
adns_addr2text (which only the IPv6-capable adns has).

Signed-off-by: Ian Jackson <ijackson at chiark.greenend.org.uk>
---
 config.h.in  |    3 ++
 configure    |  143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.in |   13 ++++++
 3 files changed, 159 insertions(+)

diff --git a/config.h.in b/config.h.in
index 74fea83..a8b73b9 100644
--- a/config.h.in
+++ b/config.h.in
@@ -8,6 +8,9 @@
 /* Define if building universal (internal helper macro) */
 #undef AC_APPLE_UNIVERSAL_BUILD
 
+/* Define to 1 to use IPv6 support in system and adns */
+#undef CONFIG_IPV6
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
diff --git a/configure b/configure
index 0a9da90..cf4e581 100755
--- a/configure
+++ b/configure
@@ -1862,6 +1862,119 @@ fi
   as_fn_set_status $ac_retval
 
 } # ac_fn_c_try_link
+
+# ac_fn_c_check_decl LINENO SYMBOL VAR INCLUDES
+# ---------------------------------------------
+# Tests whether SYMBOL is declared in INCLUDES, setting cache variable VAR
+# accordingly.
+ac_fn_c_check_decl ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  as_decl_name=`echo $2|sed 's/ *(.*//'`
+  as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
+$as_echo_n "checking whether $as_decl_name is declared... " >&6; }
+if eval \${$3+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+$4
+int
+main ()
+{
+#ifndef $as_decl_name
+#ifdef __cplusplus
+  (void) $as_decl_use;
+#else
+  (void) $as_decl_name;
+#endif
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$3=yes"
+else
+  eval "$3=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+eval ac_res=\$$3
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+
+} # ac_fn_c_check_decl
+
+# ac_fn_c_check_func LINENO FUNC VAR
+# ----------------------------------
+# Tests whether FUNC exists, setting the cache variable VAR accordingly
+ac_fn_c_check_func ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
+$as_echo_n "checking for $2... " >&6; }
+if eval \${$3+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+/* Define $2 to an innocuous variant, in case <limits.h> declares $2.
+   For example, HP-UX 11i <limits.h> declares gettimeofday.  */
+#define $2 innocuous_$2
+
+/* System header to define __stub macros and hopefully few prototypes,
+    which can conflict with char $2 (); below.
+    Prefer <limits.h> to <assert.h> if __STDC__ is defined, since
+    <limits.h> exists even on freestanding compilers.  */
+
+#ifdef __STDC__
+# include <limits.h>
+#else
+# include <assert.h>
+#endif
+
+#undef $2
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char $2 ();
+/* The GNU C library defines this for functions which it implements
+    to always fail with ENOSYS.  Some functions are actually named
+    something starting with __ and the normal name is an alias.  */
+#if defined __stub_$2 || defined __stub___$2
+choke me
+#endif
+
+int
+main ()
+{
+return $2 ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  eval "$3=yes"
+else
+  eval "$3=no"
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+eval ac_res=\$$3
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+
+} # ac_fn_c_check_func
 cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
@@ -4598,6 +4711,36 @@ fi
 
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: Checking requirements for IPv6 support..." >&5
+$as_echo "$as_me: Checking requirements for IPv6 support..." >&6;}
+enable_ipv6=true
+
+ac_fn_c_check_decl "$LINENO" "AF_INET6" "ac_cv_have_decl_AF_INET6" "#include <netinet/in.h>
+"
+if test "x$ac_cv_have_decl_AF_INET6" = xyes; then :
+
+else
+  enable_ipv6=false
+fi
+
+ac_fn_c_check_func "$LINENO" "adns_addr2text" "ac_cv_func_adns_addr2text"
+if test "x$ac_cv_func_adns_addr2text" = xyes; then :
+
+else
+  enable_ipv6=false
+fi
+
+if $enable_ipv6; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: Enabling IPv6 support" >&5
+$as_echo "$as_me: Enabling IPv6 support" >&6;}
+
+$as_echo "#define CONFIG_IPV6 1" >>confdefs.h
+
+else
+    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Disabling IPv6 support" >&5
+$as_echo "$as_me: WARNING: Disabling IPv6 support" >&2;}
+fi
+
 ac_config_files="$ac_config_files Makefile"
 
 ac_config_commands="$ac_config_commands default"
diff --git a/configure.in b/configure.in
index 747d901..0c0c545 100644
--- a/configure.in
+++ b/configure.in
@@ -70,6 +70,19 @@ AC_CHECK_LIB(resolv,inet_aton)
 AC_CHECK_LIB(adns,adns_init)
 REQUIRE_HEADER([adns.h])
 
+AC_MSG_NOTICE([Checking requirements for IPv6 support...])
+enable_ipv6=true
+m4_define(NO_IPV6,[enable_ipv6=false])
+AC_CHECK_DECL(AF_INET6,        [],[NO_IPV6],[#include <netinet/in.h>])
+AC_CHECK_FUNC(adns_addr2text,  [],[NO_IPV6])
+if $enable_ipv6; then
+    AC_MSG_NOTICE([Enabling IPv6 support])
+    AC_DEFINE(CONFIG_IPV6, 1,
+              [Define to 1 to use IPv6 support in system and adns])
+else
+    AC_MSG_WARN([Disabling IPv6 support])
+fi
+
 AC_OUTPUT(Makefile,echo timestamp >stamp-h)
 
 AH_TOP([
-- 
1.7.10.4