check for freeaddrinfo() at configuration phase

configure.ac

@@ -553,6 +553,7 @@ CURL_CHECK_FUNC_RECVFROM
 CURL_CHECK_FUNC_SEND
 CURL_CHECK_MSG_NOSIGNAL
 
+CARES_CHECK_FUNC_FREEADDRINFO
 CARES_CHECK_FUNC_GETADDRINFO
 CARES_CHECK_FUNC_GETHOSTNAME
 CARES_CHECK_FUNC_GETSERVBYPORT_R

m4/cares-functions.m4

@@ -16,7 +16,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 17
+# serial 18
 
 
 dnl CARES_INCLUDES_ARPA_INET
@@ -230,6 +230,102 @@ cares_includes_ws2tcpip="\
 ])
 
 
+dnl CARES_CHECK_FUNC_FREEADDRINFO
+dnl -------------------------------------------------
+dnl Verify if freeaddrinfo is available, prototyped,
+dnl and can be compiled. If all of these are true,
+dnl and usage has not been previously disallowed with
+dnl shell variable cares_disallow_freeaddrinfo, then
+dnl HAVE_FREEADDRINFO will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_FREEADDRINFO], [
+  AC_REQUIRE([CARES_INCLUDES_WS2TCPIP])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
+  #
+  tst_links_freeaddrinfo="unknown"
+  tst_proto_freeaddrinfo="unknown"
+  tst_compi_freeaddrinfo="unknown"
+  tst_allow_freeaddrinfo="unknown"
+  #
+  AC_MSG_CHECKING([if freeaddrinfo can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_ws2tcpip
+      $cares_includes_sys_socket
+      $cares_includes_netdb
+    ]],[[
+      freeaddrinfo(0);
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_freeaddrinfo="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_freeaddrinfo="no"
+  ])
+  #
+  if test "$tst_links_freeaddrinfo" = "yes"; then
+    AC_MSG_CHECKING([if freeaddrinfo is prototyped])
+    AC_EGREP_CPP([freeaddrinfo],[
+      $cares_includes_ws2tcpip
+      $cares_includes_sys_socket
+      $cares_includes_netdb
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_freeaddrinfo="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_freeaddrinfo="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_freeaddrinfo" = "yes"; then
+    AC_MSG_CHECKING([if freeaddrinfo is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_ws2tcpip
+        $cares_includes_sys_socket
+        $cares_includes_netdb
+      ]],[[
+        freeaddrinfo(0);
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_freeaddrinfo="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_freeaddrinfo="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_freeaddrinfo" = "yes"; then
+    AC_MSG_CHECKING([if freeaddrinfo usage allowed])
+    if test "x$cares_disallow_freeaddrinfo" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_freeaddrinfo="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_freeaddrinfo="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if freeaddrinfo might be used])
+  if test "$tst_links_freeaddrinfo" = "yes" &&
+     test "$tst_proto_freeaddrinfo" = "yes" &&
+     test "$tst_compi_freeaddrinfo" = "yes" &&
+     test "$tst_allow_freeaddrinfo" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_FREEADDRINFO, 1,
+      [Define to 1 if you have the freeaddrinfo function.])
+    ac_cv_func_freeaddrinfo="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_freeaddrinfo="no"
+  fi
+])
+
+
 dnl CARES_CHECK_FUNC_GETADDRINFO
 dnl -------------------------------------------------
 dnl Verify if getaddrinfo is available, prototyped, can