First step trying to avoid the multiple header inclusion and recursion nightmare.

Reintroduce checking for HAVE_MSG_NOSIGNAL in configure script, so that we don't depend on header inclusion order for a valid check.

Makefile.inc

@@ -8,7 +8,8 @@ ares_expand_string.c ares_parse_ptr_reply.c ares_parse_aaaa_reply.c	\
 ares_getnameinfo.c inet_net_pton.c bitncmp.c inet_ntop.c
 
 HHEADERS = ares.h ares_private.h setup.h ares_dns.h ares_version.h          \
-           nameser.h inet_net_pton.h inet_ntop.h ares_ipv6.h bitncmp.h
+           nameser.h inet_net_pton.h inet_ntop.h ares_ipv6.h bitncmp.h      \
+           setup_once.h 
 
 MANPAGES= ares_destroy.3 ares_expand_name.3 ares_expand_string.3 ares_fds.3 \
  ares_free_hostent.3 ares_free_string.3 ares_gethostbyaddr.3                \

acinclude.m4

@@ -904,6 +904,39 @@ AC_DEFUN([CURL_CHECK_FUNC_SEND], [
 ]) # AC_DEFUN
 
 
+dnl CURL_CHECK_MSG_NOSIGNAL
+dnl -------------------------------------------------
+dnl Check for MSG_NOSIGNAL
+
+AC_DEFUN([CURL_CHECK_MSG_NOSIGNAL], [
+  AC_CHECK_HEADERS(sys/types.h sys/socket.h)
+  AC_CACHE_CHECK([for MSG_NOSIGNAL], [ac_cv_msg_nosignal], [
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+      ],[
+        int flag=MSG_NOSIGNAL;
+      ])
+    ],[
+      ac_cv_msg_nosignal="yes"
+    ],[
+      ac_cv_msg_nosignal="no"
+    ])
+  ])
+  case "$ac_cv_msg_nosignal" in
+    yes)
+      AC_DEFINE_UNQUOTED(HAVE_MSG_NOSIGNAL, 1,
+        [Define to 1 if you have the MSG_NOSIGNAL flag.])
+      ;;
+  esac
+]) # AC_DEFUN
+
+
 dnl CURL_CHECK_NONBLOCKING_SOCKET
 dnl -------------------------------------------------
 dnl Check for how to set a socket to non-blocking state. There seems to exist

configure.ac

@@ -179,6 +179,8 @@ CURL_CHECK_FUNC_RECV
 
 CURL_CHECK_FUNC_SEND
 
+CURL_CHECK_MSG_NOSIGNAL
+
 dnl check for AF_INET6
 CARES_CHECK_CONSTANT(
   [

setup.h

@@ -149,4 +149,12 @@ int ares_strcasecmp(const char *s1, const char *s2);
 #endif
 #endif
 
+/*
+ * Include macros and defines that should only be processed once.
+ */
+
+#ifndef __SETUP_ONCE_H
+#include "setup_once.h"
+#endif
+
 #endif /* __ARES_SETUP_H */

setup_once.h

@@ -0,0 +1,99 @@
+#ifndef __SETUP_ONCE_H
+#define __SETUP_ONCE_H
+
+/* $Id$ */
+
+/* Copyright (C) 2004 - 2006 by Daniel Stenberg et al
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation for any purpose and without fee is hereby granted, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  M.I.T. makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as is"
+ * without express or implied warranty.
+ */
+
+
+/*
+ * If we have the MSG_NOSIGNAL define, make sure we use
+ * it as the fourth argument of send() and recv()
+ */
+
+#ifdef HAVE_MSG_NOSIGNAL
+#define SEND_4TH_ARG MSG_NOSIGNAL
+#else
+#define SEND_4TH_ARG 0
+#endif 
+
+
+/*
+ * The definitions for the return type and arguments types
+ * of functions recv() and send() belong and come from the
+ * configuration file. Do not define them in any other place.
+ *
+ * HAVE_RECV is defined if you have a function named recv()
+ * which is used to read incoming data from sockets. If your
+ * function has another name then don't define HAVE_RECV.
+ *
+ * If HAVE_RECV is defined then RECV_TYPE_ARG1, RECV_TYPE_ARG2,
+ * RECV_TYPE_ARG3, RECV_TYPE_ARG4 and RECV_TYPE_RETV must also
+ * be defined.
+ *
+ * HAVE_SEND is defined if you have a function named send()
+ * which is used to write outgoing data on a connected socket.
+ * If yours has another name then don't define HAVE_SEND.
+ *
+ * If HAVE_SEND is defined then SEND_TYPE_ARG1, SEND_QUAL_ARG2,
+ * SEND_TYPE_ARG2, SEND_TYPE_ARG3, SEND_TYPE_ARG4 and
+ * SEND_TYPE_RETV must also be defined.
+ */
+
+#ifdef HAVE_RECV
+#if !defined(RECV_TYPE_ARG1) || \
+    !defined(RECV_TYPE_ARG2) || \
+    !defined(RECV_TYPE_ARG3) || \
+    !defined(RECV_TYPE_ARG4) || \
+    !defined(RECV_TYPE_RETV)
+  /* */
+  Error Missing_definition_of_return_and_arguments_types_of_recv
+  /* */
+#else
+#define sread(x,y,z) (ssize_t)recv((RECV_TYPE_ARG1)(x), \
+                                   (RECV_TYPE_ARG2)(y), \
+                                   (RECV_TYPE_ARG3)(z), \
+                                   (RECV_TYPE_ARG4)(SEND_4TH_ARG))
+#endif
+#else /* HAVE_RECV */
+#ifdef DJGPP
+#define sread(x,y,z) (ssize_t)read_s((int)(x), (char *)(y), (int)(z))
+#endif
+#endif /* HAVE_RECV */
+
+#ifdef HAVE_SEND
+#if !defined(SEND_TYPE_ARG1) || \
+    !defined(SEND_QUAL_ARG2) || \
+    !defined(SEND_TYPE_ARG2) || \
+    !defined(SEND_TYPE_ARG3) || \
+    !defined(SEND_TYPE_ARG4) || \
+    !defined(SEND_TYPE_RETV)
+  /* */
+  Error Missing_definition_of_return_and_arguments_types_of_send
+  /* */
+#else
+#define swrite(x,y,z) (ssize_t)send((SEND_TYPE_ARG1)(x), \
+                                    (SEND_TYPE_ARG2)(y), \
+                                    (SEND_TYPE_ARG3)(z), \
+                                    (SEND_TYPE_ARG4)(SEND_4TH_ARG))
+#endif
+#else /* HAVE_SEND */
+#ifdef DJGPP
+#define swrite(x,y,z) (ssize_t)write_s((int)(x), (char *)(y), (int)(z))
+#endif
+#endif /* HAVE_SEND */
+
+
+#endif /* __SETUP_ONCE_H */
+