check for socket() and closesocket() as it is done for other functions

configure.ac

@@ -438,6 +438,7 @@ AC_CHECK_HEADERS(
        netinet/tcp.h \
        net/if.h \
        errno.h \
+       socket.h \
        strings.h \
        stdbool.h \
        time.h \
@@ -534,6 +535,7 @@ CURL_CHECK_FUNC_RECVFROM
 CURL_CHECK_FUNC_SEND
 CURL_CHECK_MSG_NOSIGNAL
 
+CARES_CHECK_FUNC_CLOSESOCKET
 CARES_CHECK_FUNC_FCNTL
 CARES_CHECK_FUNC_FREEADDRINFO
 CARES_CHECK_FUNC_GETADDRINFO
@@ -547,6 +549,7 @@ CARES_CHECK_FUNC_IOCTL
 CARES_CHECK_FUNC_IOCTLSOCKET
 CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL
 CARES_CHECK_FUNC_SETSOCKOPT
+CARES_CHECK_FUNC_SOCKET
 CARES_CHECK_FUNC_STRCASECMP
 CARES_CHECK_FUNC_STRCMPI
 CARES_CHECK_FUNC_STRDUP

m4/cares-functions.m4

@@ -16,7 +16,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 29
+# serial 30
 
 
 dnl CARES_INCLUDES_ARPA_INET
@@ -91,6 +91,27 @@ cares_includes_netdb="\
 ])
 
 
+dnl CARES_INCLUDES_SOCKET
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when socket.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_SOCKET], [
+cares_includes_socket="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+#ifdef HAVE_SOCKET_H
+#  include <socket.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h socket.h,
+    [], [], [$cares_includes_socket])
+])
+
+
 dnl CARES_INCLUDES_STDLIB
 dnl -------------------------------------------------
 dnl Set up variable with list of headers that must be
@@ -319,6 +340,100 @@ cares_preprocess_callconv="\
 ])
 
 
+dnl CARES_CHECK_FUNC_CLOSESOCKET
+dnl -------------------------------------------------
+dnl Verify if closesocket is available, prototyped, and
+dnl can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable cares_disallow_closesocket, then
+dnl HAVE_CLOSESOCKET will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_CLOSESOCKET], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  AC_REQUIRE([CARES_INCLUDES_SOCKET])dnl
+  #
+  tst_links_closesocket="unknown"
+  tst_proto_closesocket="unknown"
+  tst_compi_closesocket="unknown"
+  tst_allow_closesocket="unknown"
+  #
+  AC_MSG_CHECKING([if closesocket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+      $cares_includes_socket
+    ]],[[
+      if(0 != closesocket(0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_closesocket="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_closesocket="no"
+  ])
+  #
+  if test "$tst_links_closesocket" = "yes"; then
+    AC_MSG_CHECKING([if closesocket is prototyped])
+    AC_EGREP_CPP([closesocket],[
+      $cares_includes_winsock2
+      $cares_includes_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_closesocket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_closesocket="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_closesocket" = "yes"; then
+    AC_MSG_CHECKING([if closesocket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_socket
+      ]],[[
+        if(0 != closesocket(0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_closesocket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_closesocket="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_closesocket" = "yes"; then
+    AC_MSG_CHECKING([if closesocket usage allowed])
+    if test "x$cares_disallow_closesocket" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_closesocket="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_closesocket="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if closesocket might be used])
+  if test "$tst_links_closesocket" = "yes" &&
+     test "$tst_proto_closesocket" = "yes" &&
+     test "$tst_compi_closesocket" = "yes" &&
+     test "$tst_allow_closesocket" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_CLOSESOCKET, 1,
+      [Define to 1 if you have the closesocket function.])
+    ac_cv_func_closesocket="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_closesocket="no"
+  fi
+])
+
+
 dnl CARES_CHECK_FUNC_FCNTL
 dnl -------------------------------------------------
 dnl Verify if fcntl is available, prototyped, and
@@ -2074,6 +2189,104 @@ AC_DEFUN([CARES_CHECK_FUNC_SETSOCKOPT_SO_NONBLOCK], [
 ])
 
 
+dnl CARES_CHECK_FUNC_SOCKET
+dnl -------------------------------------------------
+dnl Verify if socket is available, prototyped, and
+dnl can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable cares_disallow_socket, then
+dnl HAVE_SOCKET will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_SOCKET], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  AC_REQUIRE([CARES_INCLUDES_SOCKET])dnl
+  #
+  tst_links_socket="unknown"
+  tst_proto_socket="unknown"
+  tst_compi_socket="unknown"
+  tst_allow_socket="unknown"
+  #
+  AC_MSG_CHECKING([if socket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+      $cares_includes_socket
+    ]],[[
+      if(0 != socket(0, 0, 0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_socket="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_socket="no"
+  ])
+  #
+  if test "$tst_links_socket" = "yes"; then
+    AC_MSG_CHECKING([if socket is prototyped])
+    AC_EGREP_CPP([socket],[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+      $cares_includes_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_socket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_socket="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_socket" = "yes"; then
+    AC_MSG_CHECKING([if socket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_sys_socket
+        $cares_includes_socket
+      ]],[[
+        if(0 != socket(0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_socket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_socket="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_socket" = "yes"; then
+    AC_MSG_CHECKING([if socket usage allowed])
+    if test "x$cares_disallow_socket" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_socket="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_socket="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if socket might be used])
+  if test "$tst_links_socket" = "yes" &&
+     test "$tst_proto_socket" = "yes" &&
+     test "$tst_compi_socket" = "yes" &&
+     test "$tst_allow_socket" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_SOCKET, 1,
+      [Define to 1 if you have the socket function.])
+    ac_cv_func_socket="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_socket="no"
+  fi
+])
+
+
 dnl CARES_CHECK_FUNC_STRCASECMP
 dnl -------------------------------------------------
 dnl Verify if strcasecmp is available, prototyped, and