From 899d252fb92c8b592b3f1d26f4e1eb2db72d0731 Mon Sep 17 00:00:00 2001
From: Christopher Kohlhoff <chris@kohlhoff.com>
Date: Sun, 13 May 2007 08:18:09 +0000
Subject: [PATCH] Allow everything to compile on platforms where IPV6_V6ONLY is
 not defined (such as Linux distros with a 2.4 kernel), but make any use of
 ip::v6_only fail at runtime.

[SVN r37681]
---
 include/boost/asio/detail/socket_ops.hpp   | 12 ++++++++++++
 include/boost/asio/detail/socket_types.hpp |  1 +
 include/boost/asio/ip/v6_only.hpp          |  6 +++++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/boost/asio/detail/socket_ops.hpp b/include/boost/asio/detail/socket_ops.hpp
index 8e6fd96b..39e065b1 100644
--- a/include/boost/asio/detail/socket_ops.hpp
+++ b/include/boost/asio/detail/socket_ops.hpp
@@ -319,6 +319,12 @@ inline socket_type socket(int af, int type, int protocol,
 inline int setsockopt(socket_type s, int level, int optname,
     const void* optval, size_t optlen, boost::system::error_code& ec)
 {
+  if (level == custom_socket_option_level && optname == always_fail_option)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return -1;
+  }
+
   clear_error(ec);
 #if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
   return error_wrapper(::setsockopt(s, level, optname,
@@ -332,6 +338,12 @@ inline int setsockopt(socket_type s, int level, int optname,
 inline int getsockopt(socket_type s, int level, int optname, void* optval,
     size_t* optlen, boost::system::error_code& ec)
 {
+  if (level == custom_socket_option_level && optname == always_fail_option)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return -1;
+  }
+
   clear_error(ec);
 #if defined(BOOST_WINDOWS) || defined(__CYGWIN__)
   int tmp_optlen = static_cast<int>(*optlen);
diff --git a/include/boost/asio/detail/socket_types.hpp b/include/boost/asio/detail/socket_types.hpp
index bf6c67f1..3a42e647 100644
--- a/include/boost/asio/detail/socket_types.hpp
+++ b/include/boost/asio/detail/socket_types.hpp
@@ -170,6 +170,7 @@ const int message_do_not_route = MSG_DONTROUTE;
 #endif
 const int custom_socket_option_level = 0xA5100000;
 const int enable_connection_aborted_option = 1;
+const int always_fail_option = 2;
 
 } // namespace detail
 } // namespace asio
diff --git a/include/boost/asio/ip/v6_only.hpp b/include/boost/asio/ip/v6_only.hpp
index efe36749..78285fd2 100644
--- a/include/boost/asio/ip/v6_only.hpp
+++ b/include/boost/asio/ip/v6_only.hpp
@@ -52,9 +52,13 @@ namespace ip {
  */
 #if defined(GENERATING_DOCUMENTATION)
 typedef implementation_defined v6_only;
-#else
+#elif defined(IPV6_V6ONLY)
 typedef boost::asio::detail::socket_option::boolean<
     IPPROTO_IPV6, IPV6_V6ONLY> v6_only;
+#else
+typedef boost::asio::detail::socket_option::boolean<
+    boost::asio::detail::custom_socket_option_level,
+    boost::asio::detail::always_fail_option> v6_only;
 #endif
 
 } // namespace ip