optional_api: Fix linking problems between modules that export global symbols

With the new work in Asterisk 12, there are some uses of the
optional_api that are prone to failure. The details are rather involved,
and captured on [the wiki][1].

This patch addresses the issue by removing almost all of the magic from
the optional API implementation. Instead of relying on weak symbol
resolution, a new optional_api.c module was added to Asterisk core.

For modules providing an optional API, the pointer to the implementation
function is registered with the core. For modules that use an optional
API, a pointer to a stub function, along with a optional_ref function
pointer are registered with the core. The optional_ref function pointers
is set to the implementation function when it's provided, or the stub
function when it's now.

Since the implementation no longer relies on magic, it is now supported
on all platforms. In the spirit of choice, an OPTIONAL_API flag was
added, so we can disable the optional_api if needed (maybe it's buggy on
some bizarre platform I haven't tested on)

The AST_OPTIONAL_API*() macros themselves remained unchanged, so
existing code could remain unchanged. But to help with debugging the
optional_api, the patch limits the #include of optional API's to just
the modules using the API. This also reduces resource waste maintaining
optional_ref pointers that aren't used.

Other changes made as a part of this patch:
 * The stubs for http_websocket that wrap system calls set errno to
   ENOSYS.

 * res_http_websocket now properly increments module use count.

 * In loader.c, the while() wrappers around dlclose() were removed. The
   while(!dlclose()) is actually an anti-pattern, which can lead to
   infinite loops if the module you're attempting to unload exports a
   symbol that was directly linked to.

 * The special handling of nonoptreq on systems without weak symbol
   support was removed, since we no longer rely on weak symbols for
   optional_api.

 [1]: https://wiki.asterisk.org/wiki/x/wACUAQ

(closes issue ASTERISK-22296)
Reported by: Matt Jordan
Review: https://reviewboard.asterisk.org/r/2797/
........

Merged revisions 397989 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@397990 65c4cc65-6c06-0410-ace0-fbb531ad65f3

22 files changed, 1011 insertions, 359 deletions

diff --git a/CHANGES b/CHANGES
index 9a223fdd1..f7078ea79 100644
--- a/CHANGES
+++ b/CHANGES
@@ -63,6 +63,9 @@ Build System
    Please see https://wiki.asterisk.org/wiki/x/J4GLAQ for more information on
    configuring and installing PJSIP for usage with Asterisk.
 
+ * Optional API was re-implemented to be more portable, and no longer requires
+   weak reference support from the compiler. The build option OPTIONAL_API may
+   be disabled to disable Optional API support.
 
 Applications
 ------------------
diff --git a/build_tools/cflags.xml b/build_tools/cflags.xml
index c4d15a67b..e7bec1672 100644
--- a/build_tools/cflags.xml
+++ b/build_tools/cflags.xml
@@ -1,4 +1,4 @@
-	<category name="MENUSELECT_CFLAGS" displayname="Compiler Flags" positive_output="yes" remove_on_change=".lastclean">
+<category name="MENUSELECT_CFLAGS" displayname="Compiler Flags" positive_output="yes" remove_on_change=".lastclean">
 		<member name="DONT_OPTIMIZE" displayname="Disable Optimizations by the Compiler">
 			<support_level>core</support_level>
 		</member>
@@ -30,6 +30,13 @@
 			  -->
 			<support_level>extended</support_level>
 		</member>
+		<member name="OPTIONAL_API" displayname="Enable the optional API">
+			<!-- Added to manually disable the optional API, since
+			     it's now supported on all systems.
+			  -->
+			<defaultenabled>yes</defaultenabled>
+			<support_level>extended</support_level>
+		</member>
 		<member name="BETTER_BACKTRACES" displayname="Use libbfd (GPL) to generate better inline backtraces">
 			<depend>BFD</depend>
 			<depend>DLADDR</depend>
diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index e6d9cffc7..55b1ed550 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -298,6 +298,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/stasis_system.h"
 #include "asterisk/stasis_channels.h"
 #include "asterisk/features_config.h"
+#include "asterisk/http_websocket.h"
 
 /*** DOCUMENTATION
 	<application name="SIPDtmfMode" language="en_US">
diff --git a/channels/sip/include/sip.h b/channels/sip/include/sip.h
index 724581b71..c0704ec79 100644
--- a/channels/sip/include/sip.h
+++ b/channels/sip/include/sip.h
@@ -35,7 +35,6 @@
 #include "asterisk/indications.h"
 #include "asterisk/security_events.h"
 #include "asterisk/features.h"
-#include "asterisk/http_websocket.h"
 #include "asterisk/rtp_engine.h"
 #include "asterisk/netsock2.h"
 #include "asterisk/features_config.h"
@@ -769,6 +768,8 @@ struct sip_settings {
 	int default_max_forwards;    /*!< Default max forwards (SIP Anti-loop) */
 };
 
+struct ast_websocket;
+
 /*! \brief The SIP socket definition */
 struct sip_socket {
 	enum ast_transport type;  /*!< UDP, TCP or TLS */
diff --git a/configure b/configure
index 2d04b6d11..3dff95f60 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.ac Revision: 395985 .
+# From configure.ac Revision: 397868 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.69 for asterisk trunk.
 #
@@ -684,6 +684,7 @@ PKG_CONFIG_PATH
 PKG_CONFIG
 PBX_DLADDR
 PBX_IP_MTU_DISCOVER
+PBX_RTLD_NOLOAD
 PBX_GLOB_BRACE
 PBX_GLOB_NOMAGIC
 AST_RPATH
@@ -696,7 +697,6 @@ AST_TRAMPOLINES
 AST_DECLARATION_AFTER_STATEMENT
 GC_LDFLAGS
 GC_CFLAGS
-PBX_WEAKREF
 PBX_PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
 PBX_PTHREAD_RWLOCK_INITIALIZER
 AST_ASTERISKSSL
@@ -16564,28 +16564,17 @@ CFLAGS="$saved_CFLAGS"
 
 
 
-# Support weak symbols on a platform specific basis.  The Mac OS X
-# (Darwin) support must be isolated from the other platforms because
-# it has caused other platforms to fail.
-#
-case "${OSARCH}" in
-	darwin*)
-	# Allow weak symbol support on Darwin platforms only because there
-	# is active community support for it.
-	# However, Darwin seems to break weak symbols for each new version.
-	#
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute weak_import' support" >&5
-$as_echo_n "checking for compiler 'attribute weak_import' support... " >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute may_alias' support" >&5
+$as_echo_n "checking for compiler 'attribute may_alias' support... " >&6; }
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Wall -Wno-unused -Werror"
-PBX_WEAKREF=0
+
 
 if test "x" = "x"
 then
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
- void __attribute__((weak_import)) *test(void *muffin, ...) {return (void *) 0;}
+ void __attribute__((may_alias)) *test(void *muffin, ...) {return (void *) 0;}
 int
 main ()
 {
@@ -16597,10 +16586,10 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	PBX_WEAKREF=1
+
 
 cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weak_import 1
+#define HAVE_ATTRIBUTE_may_alias 1
 _ACEOF
 
 else
@@ -16624,10 +16613,10 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	PBX_WEAKREF=1
+
 
 cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weak_import 1
+#define HAVE_ATTRIBUTE_may_alias 1
 _ACEOF
 
 else
@@ -16643,21 +16632,17 @@ CFLAGS="$saved_CFLAGS"
 
 
 
-	# Several other platforms including Linux have GCC versions that
-	# define the weak attribute.  However, this attribute is only
-	# setup for use in the code by Darwin.
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute weak' support" >&5
-$as_echo_n "checking for compiler 'attribute weak' support... " >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute constructor' support" >&5
+$as_echo_n "checking for compiler 'attribute constructor' support... " >&6; }
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Wall -Wno-unused -Werror"
-PBX_WEAKREF=0
+
 
 if test "x" = "x"
 then
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
- void __attribute__((weak)) *test(void *muffin, ...) {return (void *) 0;}
+ void __attribute__((constructor)) *test(void *muffin, ...) {return (void *) 0;}
 int
 main ()
 {
@@ -16669,10 +16654,10 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	PBX_WEAKREF=1
+
 
 cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weak 1
+#define HAVE_ATTRIBUTE_constructor 1
 _ACEOF
 
 else
@@ -16696,82 +16681,10 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	PBX_WEAKREF=1
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weak 1
-_ACEOF
-
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-
-
-CFLAGS="$saved_CFLAGS"
-
-
-	;;
-	linux-gnu)
-	# Primarily support weak symbols on Linux platforms.
-	#
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute weakref' support" >&5
-$as_echo_n "checking for compiler 'attribute weakref' support... " >&6; }
-saved_CFLAGS="$CFLAGS"
-CFLAGS="$CFLAGS -Wall -Wno-unused -Werror"
-PBX_WEAKREF=0
-
-if test "xweakref("foo")" = "x"
-then
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-static void __attribute__((weakref)) *test(void *muffin, ...) {return (void *) 0;}
-int
-main ()
-{
 
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-	PBX_WEAKREF=1
 
 cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weakref 1
-_ACEOF
-
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-else
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-static void __attribute__((weakref("foo"))) *test(void *muffin, ...) {return (void *) 0;}
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-	PBX_WEAKREF=1
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weakref 1
+#define HAVE_ATTRIBUTE_constructor 1
 _ACEOF
 
 else
@@ -16786,24 +16699,18 @@ fi
 CFLAGS="$saved_CFLAGS"
 
 
-	;;
-	*)
-	# Allow weak symbols on other platforms.  However, any problems
-	# with this feature on other platforms must be fixed by the
-	# community.
-	#
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute weakref' support" >&5
-$as_echo_n "checking for compiler 'attribute weakref' support... " >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler 'attribute destructor' support" >&5
+$as_echo_n "checking for compiler 'attribute destructor' support... " >&6; }
 saved_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -Wall -Wno-unused -Werror"
-PBX_WEAKREF=0
 
-if test "xweakref("foo")" = "x"
+
+if test "x" = "x"
 then
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
-static void __attribute__((weakref)) *test(void *muffin, ...) {return (void *) 0;}
+ void __attribute__((destructor)) *test(void *muffin, ...) {return (void *) 0;}
 int
 main ()
 {
@@ -16815,10 +16722,10 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	PBX_WEAKREF=1
+
 
 cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weakref 1
+#define HAVE_ATTRIBUTE_destructor 1
 _ACEOF
 
 else
@@ -16830,7 +16737,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 else
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
-static void __attribute__((weakref("foo"))) *test(void *muffin, ...) {return (void *) 0;}
+ void __attribute__(()) *test(void *muffin, ...) {return (void *) 0;}
 int
 main ()
 {
@@ -16842,10 +16749,10 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	PBX_WEAKREF=1
+
 
 cat >>confdefs.h <<_ACEOF
-#define HAVE_ATTRIBUTE_weakref 1
+#define HAVE_ATTRIBUTE_destructor 1
 _ACEOF
 
 else
@@ -16860,8 +16767,6 @@ fi
 CFLAGS="$saved_CFLAGS"
 
 
-	;;
-esac
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -ffunction-sections support" >&5
 $as_echo_n "checking for -ffunction-sections support... " >&6; }
@@ -17454,6 +17359,53 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
+    if test "x${PBX_RTLD_NOLOAD}" != "x1"; then
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for RTLD_NOLOAD in dlfcn.h" >&5
+$as_echo_n "checking for RTLD_NOLOAD in dlfcn.h... " >&6; }
+	saved_cppflags="${CPPFLAGS}"
+	if test "x${RTLD_NOLOAD_DIR}" != "x"; then
+	    RTLD_NOLOAD_INCLUDE="-I${RTLD_NOLOAD_DIR}/include"
+	fi
+	CPPFLAGS="${CPPFLAGS} ${RTLD_NOLOAD_INCLUDE}"
+
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+ #include <dlfcn.h>
+int
+main ()
+{
+#if defined(RTLD_NOLOAD)
+				int foo = 0;
+			        #else
+			        int foo = bar;
+			        #endif
+				0
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+     { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+		PBX_RTLD_NOLOAD=1
+
+$as_echo "#define HAVE_RTLD_NOLOAD 1" >>confdefs.h
+
+
+
+else
+     { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+	CPPFLAGS="${saved_cppflags}"
+    fi
+
+
+
+
     if test "x${PBX_IP_MTU_DISCOVER}" != "x1"; then
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for IP_MTU_DISCOVER in netinet/in.h" >&5
 $as_echo_n "checking for IP_MTU_DISCOVER in netinet/in.h... " >&6; }
diff --git a/configure.ac b/configure.ac
index 69228b517..e409327fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -957,37 +957,9 @@ AST_GCC_ATTRIBUTE(always_inline)
 AST_GCC_ATTRIBUTE(deprecated)
 AST_GCC_ATTRIBUTE(sentinel)
 AST_GCC_ATTRIBUTE(warn_unused_result)
-
-# Support weak symbols on a platform specific basis.  The Mac OS X
-# (Darwin) support must be isolated from the other platforms because
-# it has caused other platforms to fail.
-#
-case "${OSARCH}" in
-	darwin*)
-	# Allow weak symbol support on Darwin platforms only because there
-	# is active community support for it.
-	# However, Darwin seems to break weak symbols for each new version.
-	#
-	AST_GCC_ATTRIBUTE(weak_import, [], [], PBX_WEAKREF)
-
-	# Several other platforms including Linux have GCC versions that
-	# define the weak attribute.  However, this attribute is only
-	# setup for use in the code by Darwin.
-	AST_GCC_ATTRIBUTE(weak, [], [], PBX_WEAKREF)
-	;;
-	linux-gnu)
-	# Primarily support weak symbols on Linux platforms.
-	#
-	AST_GCC_ATTRIBUTE(weakref, [weakref("foo")], static, PBX_WEAKREF)
-	;;
-	*)
-	# Allow weak symbols on other platforms.  However, any problems
-	# with this feature on other platforms must be fixed by the
-	# community.
-	#
-	AST_GCC_ATTRIBUTE(weakref, [weakref("foo")], static, PBX_WEAKREF)
-	;;
-esac
+AST_GCC_ATTRIBUTE(may_alias)
+AST_GCC_ATTRIBUTE(constructor)
+AST_GCC_ATTRIBUTE(destructor)
 
 AC_MSG_CHECKING(for -ffunction-sections support)
 saved_CFLAGS="${CFLAGS}"
@@ -1181,6 +1153,8 @@ AST_C_DEFINE_CHECK([GLOB_NOMAGIC], [GLOB_NOMAGIC], [glob.h])
 
 AST_C_DEFINE_CHECK([GLOB_BRACE], [GLOB_BRACE], [glob.h])
 
+AST_C_DEFINE_CHECK([RTLD_NOLOAD], [RTLD_NOLOAD], [dlfcn.h])
+
 AST_C_DEFINE_CHECK([IP_MTU_DISCOVER], [IP_MTU_DISCOVER], [netinet/in.h])
 
 AC_CHECK_HEADER([libkern/OSAtomic.h],
diff --git a/include/asterisk/ari.h b/include/asterisk/ari.h
index 4f2954000..dfeef513c 100644
--- a/include/asterisk/ari.h
+++ b/include/asterisk/ari.h
@@ -21,7 +21,7 @@
 
 /*! \file
  *
- * \brief Stasis RESTful API hooks.
+ * \brief Asterisk RESTful API hooks.
  *
  * This header file is used mostly as glue code between generated declarations
  * and res_ari.c.
@@ -31,7 +31,14 @@
 
 #include "asterisk/http.h"
 #include "asterisk/json.h"
-#include "asterisk/http_websocket.h"
+
+/* Forward-declare websocket structs. This avoids including http_websocket.h,
+ * which causes optional_api stuff to happen, which makes optional_api more
+ * difficult to debug. */
+
+struct ast_websocket_server;
+
+struct ast_websocket;
 
 /*!
  * \brief Configured encoding format for JSON output.
diff --git a/include/asterisk/autoconfig.h.in b/include/asterisk/autoconfig.h.in
index 1796a3f68..87a769ed0 100644
--- a/include/asterisk/autoconfig.h.in
+++ b/include/asterisk/autoconfig.h.in
@@ -82,12 +82,21 @@
 /* Define to 1 if your GCC C compiler supports the 'const' attribute. */
 #undef HAVE_ATTRIBUTE_const
 
+/* Define to 1 if your GCC C compiler supports the 'constructor' attribute. */
+#undef HAVE_ATTRIBUTE_constructor
+
 /* Define to 1 if your GCC C compiler supports the 'deprecated' attribute. */
 #undef HAVE_ATTRIBUTE_deprecated
 
+/* Define to 1 if your GCC C compiler supports the 'destructor' attribute. */
+#undef HAVE_ATTRIBUTE_destructor
+
 /* Define to 1 if your GCC C compiler supports the 'malloc' attribute. */
 #undef HAVE_ATTRIBUTE_malloc
 
+/* Define to 1 if your GCC C compiler supports the 'may_alias' attribute. */
+#undef HAVE_ATTRIBUTE_may_alias
+
 /* Define to 1 if your GCC C compiler supports the 'pure' attribute. */
 #undef HAVE_ATTRIBUTE_pure
 
@@ -101,15 +110,6 @@
    attribute. */
 #undef HAVE_ATTRIBUTE_warn_unused_result
 
-/* Define to 1 if your GCC C compiler supports the 'weak' attribute. */
-#undef HAVE_ATTRIBUTE_weak
-
-/* Define to 1 if your GCC C compiler supports the 'weak_import' attribute. */
-#undef HAVE_ATTRIBUTE_weak_import
-
-/* Define to 1 if your GCC C compiler supports the 'weakref' attribute. */
-#undef HAVE_ATTRIBUTE_weakref
-
 /* Define to 1 if you have the Debug symbol decoding library. */
 #undef HAVE_BFD
 
@@ -720,6 +720,9 @@
 /* Define to 1 if you have the `roundl' function. */
 #undef HAVE_ROUNDL
 
+/* Define if your system has the RTLD_NOLOAD headers. */
+#undef HAVE_RTLD_NOLOAD
+
 /* Define to 1 if your system has /sbin/launchd. */
 #undef HAVE_SBIN_LAUNCHD
 
diff --git a/include/asterisk/compiler.h b/include/asterisk/compiler.h
index 91112dbfe..77b5de40e 100644
--- a/include/asterisk/compiler.h
+++ b/include/asterisk/compiler.h
@@ -71,6 +71,12 @@
 #define attribute_warn_unused_result
 #endif
 
+#ifdef HAVE_ATTRIBUTE_may_alias
+#define attribute_may_alias __attribute__((may_alias))
+#else
+#define attribute_may_alias
+#endif
+
 /* Some older version of GNU gcc (3.3.5 on OpenBSD 4.3 for example) dont like 'NULL' as sentinel */
 #define SENTINEL ((char *)NULL)
 
diff --git a/include/asterisk/http_websocket.h b/include/asterisk/http_websocket.h
index 82c7ad8b6..10cb9a023 100644
--- a/include/asterisk/http_websocket.h
+++ b/include/asterisk/http_websocket.h
@@ -22,6 +22,8 @@
 #include "asterisk/http.h"
 #include "asterisk/optional_api.h"
 
+#include <errno.h>
+
 /*!
  * \file http_websocket.h
  * \brief Support for WebSocket connections within the Asterisk HTTP server.
@@ -71,7 +73,7 @@ typedef void (*ast_websocket_callback)(struct ast_websocket *session, struct ast
  * \retval \c NULL on error
  * \since 12
  */
-struct ast_websocket_server *ast_websocket_server_create(void);
+AST_OPTIONAL_API(struct ast_websocket_server *, ast_websocket_server_create, (void), { return NULL; });
 
 /*!
  * \brief Callback suitable for use with a \ref ast_http_uri.
@@ -79,7 +81,7 @@ struct ast_websocket_server *ast_websocket_server_create(void);
  * Set the data field of the ast_http_uri to \ref ast_websocket_server.
  * \since 12
  */
-int ast_websocket_uri_cb(struct ast_tcptls_session_instance *ser, const struct ast_http_uri *urih, const char *uri, enum ast_http_method method, struct ast_variable *get_vars, struct ast_variable *headers);
+AST_OPTIONAL_API(int, ast_websocket_uri_cb, (struct ast_tcptls_session_instance *ser, const struct ast_http_uri *urih, const char *uri, enum ast_http_method method, struct ast_variable *get_vars, struct ast_variable *headers), { return -1; });
 
 /*!
  * \brief Add a sub-protocol handler to the default /ws server
@@ -141,7 +143,7 @@ AST_OPTIONAL_API(int, ast_websocket_server_remove_protocol, (struct ast_websocke
  *
  * \note Once an AST_WEBSOCKET_OPCODE_CLOSE opcode is received the socket will be closed
  */
-AST_OPTIONAL_API(int, ast_websocket_read, (struct ast_websocket *session, char **payload, uint64_t *payload_len, enum ast_websocket_opcode *opcode, int *fragmented), {return -1;});
+AST_OPTIONAL_API(int, ast_websocket_read, (struct ast_websocket *session, char **payload, uint64_t *payload_len, enum ast_websocket_opcode *opcode, int *fragmented), { errno = ENOSYS; return -1;});
 
 /*!
  * \brief Construct and transmit a WebSocket frame
@@ -154,7 +156,7 @@ AST_OPTIONAL_API(int, ast_websocket_read, (struct ast_websocket *session, char *
  * \retval 0 if successfully written
  * \retval -1 if error occurred
  */
-AST_OPTIONAL_API(int, ast_websocket_write, (struct ast_websocket *session, enum ast_websocket_opcode opcode, char *payload, uint64_t actual_length), {return -1;});
+AST_OPTIONAL_API(int, ast_websocket_write, (struct ast_websocket *session, enum ast_websocket_opcode opcode, char *payload, uint64_t actual_length), { errno = ENOSYS; return -1;});
 
 /*!
  * \brief Close a WebSocket session by sending a message with the CLOSE opcode and an optional code
@@ -165,7 +167,7 @@ AST_OPTIONAL_API(int, ast_websocket_write, (struct ast_websocket *session, enum
  * \retval 0 if successfully written
  * \retval -1 if error occurred
  */
-AST_OPTIONAL_API(int, ast_websocket_close, (struct ast_websocket *session, uint16_t reason), {return -1;});
+AST_OPTIONAL_API(int, ast_websocket_close, (struct ast_websocket *session, uint16_t reason), { errno = ENOSYS; return -1;});
 
 /*!
  * \brief Enable multi-frame reconstruction up to a certain number of bytes
@@ -207,7 +209,7 @@ AST_OPTIONAL_API(void, ast_websocket_unref, (struct ast_websocket *session), {re
  *
  * \note You must *not* directly read from or write to this file descriptor. It should only be used for polling.
  */
-AST_OPTIONAL_API(int, ast_websocket_fd, (struct ast_websocket *session), {return -1;});
+AST_OPTIONAL_API(int, ast_websocket_fd, (struct ast_websocket *session), { errno = ENOSYS; return -1;});
 
 /*!
  * \brief Get the remote address for a WebSocket connected session.
@@ -222,7 +224,7 @@ AST_OPTIONAL_API(struct ast_sockaddr *, ast_websocket_remote_address, (struct as
  * \retval 0 if unsecure
  * \retval 1 if secure
  */
-AST_OPTIONAL_API(int, ast_websocket_is_secure, (struct ast_websocket *session), {return -1;});
+AST_OPTIONAL_API(int, ast_websocket_is_secure, (struct ast_websocket *session), { errno = ENOSYS; return -1;});
 
 /*!
  * \brief Set the socket of a WebSocket session to be non-blocking.
@@ -230,6 +232,6 @@ AST_OPTIONAL_API(int, ast_websocket_is_secure, (struct ast_websocket *session),
  * \retval 0 on success
  * \retval -1 on failure
  */
-AST_OPTIONAL_API(int, ast_websocket_set_nonblock, (struct ast_websocket *session), {return -1;});
+AST_OPTIONAL_API(int, ast_websocket_set_nonblock, (struct ast_websocket *session), { errno = ENOSYS; return -1;});
 
 #endif
diff --git a/include/asterisk/optional_api.h b/include/asterisk/optional_api.h
index cc31ce0a6..7d66d2e47 100644
--- a/include/asterisk/optional_api.h
+++ b/include/asterisk/optional_api.h
@@ -1,7 +1,7 @@
 /*
  * Asterisk -- An open source telephony toolkit.
  *
- * Copyright (C) 2008, Digium, Inc.
+ * Copyright (C) 2008-2013, Digium, Inc.
  *
  * Kevin P. Fleming <kpfleming@digium.com>
  *
@@ -30,19 +30,6 @@
  * have only a part of their functionality dependent on the APIs, and can
  * provide the remainder even if the APIs are not available.
  *
- * To accomodate this situation, the AST_OPTIONAL_API macro allows an API
- * function to be declared in a special way, if Asterisk being built on a
- * platform that supports special compiler and dynamic linker attributes.
- * If so the API function will actually be a weak symbol, which means if the
- * provider of the API is not loaded, the symbol can still be referenced (unlike a
- * strong symbol, which would cause an immediate fault if not defined when
- * referenced), but it will return NULL signifying the linker/loader was
- * not able to resolve the symbol. In addition, the macro defines a hidden
- * 'stub' version of the API call, using a provided function body, and uses
- * various methods to make the API function symbol actually resolve to
- * that hidden stub, but only when the *real* provider of the symbol has
- * not been found.
- *
  * An example can be found in agi.h:
  *
  * \code
@@ -74,19 +61,6 @@
  * apply special aliases to the function prototype; this can be done
  * by defining AST_API_MODULE just before including the header file
  * containing the AST_OPTIONAL_API macro calls.
- *
- * \note If the platform does not provide adequate resources,
- * then the AST_OPTIONAL_API macro will result in a non-optional function
- * definition; this means that any consumers of the API functions so
- * defined will require that the provider of the API functions be
- * loaded before they can reference the symbols.
- *
- * WARNING WARNING WARNING WARNING WARNING
- *
- * You MUST add the AST_MODFLAG_GLOBAL_SYMBOLS to the module for which you
- * are enabling optional_api functionality, or it will fail to work.
- *
- * WARNING WARNING WARNING WARNING WARNING
  */
 
 /*!
@@ -99,150 +73,185 @@
  */
 #define AST_OPTIONAL_API_UNAVAILABLE	INT_MIN
 
-
-#if defined(HAVE_ATTRIBUTE_weak_import) || defined(HAVE_ATTRIBUTE_weak)
-
-/*
- * This is the Darwin (Mac OS/X) implementation, that only provides the 'weak'
- * or 'weak_import' compiler attribute for weak symbols. On this platform,
- *
- * - The module providing the API will only provide a '__' prefixed version
- *   of the API function to other modules (this will be hidden from the other
- *   modules by the macros), so any modules compiled against older versions
- *   of the module that provided a non-prefixed version of the API function
- *   will fail to link at runtime.
- * - In the API module itself, access to the API function without using a
- *   prefixed name is provided by a static pointer variable that holds the
- *   function address.
- * - 'Consumer' modules of the API will use a combination of a weak_import or
- *   weak symbol, a local stub function, a pointer variable and a constructor
- *   function (which initializes that pointer variable as the module is being
- *   loaded) to provide safe, optional access to the API function without any
- *   special code being required.
+/*!
+ * \def AST_OPTIONAL_API_NAME(name)
+ * \brief Expands to the name of the implementation function.
  */
 
-#if defined(HAVE_ATTRIBUTE_weak_import)
-#define	__default_attribute	weak_import /* pre-Lion */
-#else
-#define	__default_attribute	weak        /* Lion-onwards */
-#endif
-
-#define AST_OPTIONAL_API_NAME(name) __##name
-
-#if defined(AST_API_MODULE)
+/*!
+ * \def AST_OPTIONAL_API(result, name, proto, stub)
+ * \brief Declare an optional API function
+ *
+ * \param result The type of result the function returns
+ * \param name The name of the function
+ * \param proto The prototype (arguments) of the function
+ * \param stub The code block that will be used by the hidden stub when needed
+ *
+ * Example usage:
+ * \code
+ * AST_OPTIONAL_API(int, ast_agi_register, (struct ast_module *mod, agi_command *cmd),
+ *                  { return AST_OPTIONAL_API_UNAVAILABLE; });
+ * \endcode
+ */
 
-#define AST_OPTIONAL_API(result, name, proto, stub) \
-	result AST_OPTIONAL_API_NAME(name) proto; \
-	static attribute_unused typeof(AST_OPTIONAL_API_NAME(name)) * const name = AST_OPTIONAL_API_NAME(name);
+/*!
+ * \def AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub)
+ * \brief Declare an optional API function with compiler attributes
+ *
+ * \param result The type of result the function returns
+ * \param attr Any compiler attributes to be applied to the function (without the __attribute__ wrapper)
+ * \param name The name of the function
+ * \param proto The prototype (arguments) of the function
+ * \param stub The code block that will be used by the hidden stub when needed
+ */
 
-#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub)	\
-	result __attribute__((attr)) AST_OPTIONAL_API_NAME(name) proto; \
-	static attribute_unused typeof(AST_OPTIONAL_API_NAME(name)) * const name = AST_OPTIONAL_API_NAME(name);
+#if defined(OPTIONAL_API)
 
-#else
+#if !defined(HAVE_ATTRIBUTE_constructor) || !defined(HAVE_ATTRIBUTE_constructor)
+#error OPTIONAL_API requires compiler constructor/destructor support
+#endif
 
-#define AST_OPTIONAL_API(result, name, proto, stub) \
-	static result __stub__##name proto stub; \
-	__attribute__((__default_attribute)) typeof(__stub__##name) AST_OPTIONAL_API_NAME(name); \
-	static attribute_unused typeof(__stub__##name) * name; \
-	static void __attribute__((constructor)) __init__##name(void) { name = AST_OPTIONAL_API_NAME(name) ? : __stub__##name; }
+/*!
+ * \internal
+ * \brief Function pointer to an optional API function.
+ *
+ * Functions that are declared as optional may have any signature they want;
+ * they are cast to this type as needed. We don't use a \c void pointer, because
+ * technically data and function pointers are incompatible.
+ *
+ * \note
+ * The may_alias attribute is to avoid type punning/strict aliasing warnings
+ * with older GCC's.
+ */
+typedef void (*ast_optional_fn)(void) attribute_may_alias;
 
-#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub) \
-	static __attribute__((attr)) result __stub__##name proto stub; \
-	__attribute__((attr, __default_attribute)) typeof(__stub__##name) AST_OPTIONAL_API_NAME(name); \
-	static attribute_unused __attribute__((attr)) typeof(__stub__##name) * name; \
-	static void __attribute__((constructor)) __init__##name(void) { name = AST_OPTIONAL_API_NAME(name) ? : __stub__##name; }
+/*!
+ * \internal
+ * \brief Provide an implementation of an optional API.
+ *
+ * Any declared usages of this function are linked.
+ *
+ * \param symname Name of the provided function.
+ * \param impl Function pointer to the implementation function.
+ */
+void ast_optional_api_provide(const char *symname, ast_optional_fn impl);
 
-#endif
+/*!
+ * \internal
+ * \brief Remove an implementation of an optional API.
+ *
+ * Any declared usages of this function are unlinked.
+ *
+ * \param symname Name of the provided function.
+ * \param impl Function pointer to the implementation function.
+ */
+void ast_optional_api_unprovide(const char *symname, ast_optional_fn impl);
 
-/* End of Darwin (Mac OS/X) implementation */
+/*!
+ * \internal
+ * \brief Define a usage of an optional API.
+ *
+ * If the API has been provided, it will be linked into \a optional_ref.
+ * Otherwise, it will be linked to \a stub until an implementation is provided.
+ *
+ * \param symname Name of the function to use.
+ * \param optional_ref Pointer-to-function-pointer to link to impl/stub.
+ * \param stub Stub function to link to when impl is not available.
+ * \param module Name of the module requesting the API.
+ */
+void ast_optional_api_use(const char *symname, ast_optional_fn *optional_ref,
+	ast_optional_fn stub, const char *module);
 
-#elif defined(HAVE_ATTRIBUTE_weakref)
+/*!
+ * \internal
+ * \brief Remove a usage of an optional API.
+ *
+ * The \a optional_ref will be linked to the \a stub provided at use time,
+ * will no longer be updated if the API is provided/removed.
+ *
+ * \param symname Name of the function to use.
+ * \param optional_ref Pointer-to-function-pointer to link to impl/stub.
+ * \param module Name of the module requesting the API.
+ */
+void ast_optional_api_unuse(const char *symname, ast_optional_fn *optional_ref,
+	const char *module);
 
-/*
- * This is the generic GCC implementation, used when the 'weakref'
- * compiler attribute is available. On these platforms:
- *
- * - The module providing the API will provide a '__' prefixed version
- *   of the API function to other modules (this will be hidden from the other
- *   modules by the macros), and also a non-prefixed alias so that modules
- *   compiled against older versions of the module that provided a non-prefixed
- *    version of the API function will continue to link properly.
- * - In the API module itself, access to the API function without using a
- *   prefixed name is provided by the non-prefixed alias described above.
- * - 'Consumer' modules of the API will use a combination of a weakref
- *   symbol, a local stub function, a pointer variable and a constructor function
- *   (which initializes that pointer variable as the module is being loaded)
- *   to provide safe, optional access to the API function without any special
- *   code being required.
+/*!
+ * \brief Call at exit to clean up optional_api internals.
+ *
+ * Since the optional_api code might run before main() starts, it can't safely
+ * register its own cleanup handlers. That has to be done within main().
  */
+void optional_api_cleanup(void);
 
 #define AST_OPTIONAL_API_NAME(name) __##name
 
 #if defined(AST_API_MODULE)
-
-#define AST_OPTIONAL_API(result, name, proto, stub) \
-	result AST_OPTIONAL_API_NAME(name) proto; \
-	static __attribute__((alias(__stringify(AST_OPTIONAL_API_NAME(name))))) typeof(AST_OPTIONAL_API_NAME(name)) name;
-
-#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub)	\
-	result __attribute__((attr)) AST_OPTIONAL_API_NAME(name) proto; \
-	static __attribute__((alias(__stringify(AST_OPTIONAL_API_NAME(name))))) typeof(AST_OPTIONAL_API_NAME(name)) name;
+/* Module defining the API */
+
+#define AST_OPTIONAL_API_IMPL_INIT(name)				\
+	static void __attribute__((constructor)) __init__##name##_impl(void) { \
+		ast_optional_api_provide(#name,				\
+			(ast_optional_fn)AST_OPTIONAL_API_NAME(name));	\
+	}								\
+	static void __attribute__((destructor)) __dtor__##name##_impl(void) { \
+		ast_optional_api_unprovide(#name,			\
+			(ast_optional_fn)AST_OPTIONAL_API_NAME(name));	\
+	}
+
+#define AST_OPTIONAL_API(result, name, proto, stub)			\
+	result AST_OPTIONAL_API_NAME(name) proto;			\
+	static attribute_unused typeof(AST_OPTIONAL_API_NAME(name)) * const \
+	     name = AST_OPTIONAL_API_NAME(name);			\
+	AST_OPTIONAL_API_IMPL_INIT(name)
+
+#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub)		\
+	result  __attribute__((attr)) AST_OPTIONAL_API_NAME(name) proto; \
+	static attribute_unused typeof(AST_OPTIONAL_API_NAME(name)) * const \
+	     name = AST_OPTIONAL_API_NAME(name);			\
+	AST_OPTIONAL_API_IMPL_INIT(name)
 
 #else
+/* Module using the API */
 
-#define AST_OPTIONAL_API(result, name, proto, stub) \
-	static result __stub__##name proto stub; \
-	static __attribute__((weakref(__stringify(AST_OPTIONAL_API_NAME(name))))) typeof(__stub__##name) __ref__##name; \
-	static attribute_unused typeof(__stub__##name) * name; \
-	static void __attribute__((constructor)) __init__##name(void) { name = __ref__##name ? : __stub__##name; }
+#define AST_OPTIONAL_API_INIT(name)					\
+	static void __attribute__((constructor)) __init__##name(void) {	\
+		ast_optional_api_use(#name, (ast_optional_fn *)&name,	\
+			(ast_optional_fn)__stub__##name,		\
+			AST_MODULE);					\
+	}								\
+	static void __attribute__((destructor)) __dtor__##name(void) {	\
+		ast_optional_api_unuse(#name, (ast_optional_fn *)&name, \
+			AST_MODULE);					\
+	}
 
-#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub) \
-	static __attribute__((attr)) result __stub__##name proto stub; \
-	static __attribute__((attr, weakref(__stringify(AST_OPTIONAL_API_NAME(name))))) typeof(__stub__##name) __ref__##name; \
-	static attribute_unused __attribute__((attr)) typeof(__stub__##name) * name; \
-	static void __attribute__((constructor)) __init__##name(void) { name = __ref__##name ? : __stub__##name; }
+#define AST_OPTIONAL_API(result, name, proto, stub)			\
+	static result __stub__##name proto stub;			\
+	static attribute_unused						\
+		typeof(__stub__##name) * name;				\
+	AST_OPTIONAL_API_INIT(name)
 
-#endif
+#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub)		\
+	static __attribute__((attr)) result __stub__##name proto stub;	\
+	static attribute_unused	__attribute__((attr))			\
+		typeof(__stub__##name) * name;				\
+	AST_OPTIONAL_API_INIT(name)
 
-/* End of GCC implementation */
+#endif /* defined(AST_API_MODULE) */
 
-#else
+#else /* defined(OPTIONAL_API) */
 
-/* This is the non-optional implementation. */
+/* Non-optional API */
 
 #define AST_OPTIONAL_API_NAME(name) name
 
-/*!
- * \brief Define an optional API function
- *
- * \param result The type of result the function returns
- * \param name The name of the function
- * \param proto The prototype (arguments) of the function
- * \param stub The code block that will be used by the hidden stub when needed
- *
- * Example usage:
- * \code
- * AST_OPTIONAL_API(int, ast_agi_register, (struct ast_module *mod, agi_command *cmd),
- *                  { return AST_OPTIONAL_API_UNAVAILABLE; });
- * \endcode		 
- */
-#define AST_OPTIONAL_API(result, name, proto, stub) result AST_OPTIONAL_API_NAME(name) proto
+#define AST_OPTIONAL_API(result, name, proto, stub)	\
+	result AST_OPTIONAL_API_NAME(name) proto
 
-/*!
- * \brief Define an optional API function with compiler attributes
- *
- * \param result The type of result the function returns
- * \param attr Any compiler attributes to be applied to the function (without the __attribute__ wrapper)
- * \param name The name of the function
- * \param proto The prototype (arguments) of the function
- * \param stub The code block that will be used by the hidden stub when needed
- */
-#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub) result __attribute__((attr)) AST_OPTIONAL_API_NAME(name) proto
-
-/* End of non-optional implementation */
+#define AST_OPTIONAL_API_ATTR(result, attr, name, proto, stub)	\
+	result __attribute__((attr)) AST_OPTIONAL_API_NAME(name) proto
 
-#endif
+#endif /* defined(OPTIONAL_API) */
 
 #undef AST_API_MODULE
 
diff --git a/main/asterisk.c b/main/asterisk.c
index 7e5ddac58..df5561860 100644
--- a/main/asterisk.c
+++ b/main/asterisk.c
@@ -247,6 +247,7 @@ int daemon(int, int);  /* defined in libresolv of all places */
 #include "asterisk/stasis_endpoints.h"
 #include "asterisk/stasis_system.h"
 #include "asterisk/security_events.h"
+#include "asterisk/optional_api.h"
 
 #include "../defaults.h"
 
@@ -4165,6 +4166,10 @@ int main(int argc, char *argv[])
 			ast_el_read_history(filename);
 	}
 
+#if defined(OPTIONAL_API)
+	ast_register_cleanup(optional_api_cleanup);
+#endif
+
 	ast_json_init();
 	ast_ulaw_init();
 	ast_alaw_init();
diff --git a/main/loader.c b/main/loader.c
index ddfbffe9f..4065043aa 100644
--- a/main/loader.c
+++ b/main/loader.c
@@ -185,6 +185,8 @@ void ast_module_register(const struct ast_module_info *info)
 		mod = resource_being_loaded;
 	}
 
+	ast_verb(5, "Registering module %s\n", info->name);
+
 	mod->info = info;
 	AST_LIST_HEAD_INIT(&mod->users);
 
@@ -230,6 +232,7 @@ void ast_module_unregister(const struct ast_module_info *info)
 	AST_LIST_UNLOCK(&module_list);
 
 	if (mod) {
+		ast_verb(5, "Unregistering module %s\n", info->name);
 		AST_LIST_HEAD_DESTROY(&mod->users);
 		ast_free(mod);
 	}
@@ -403,16 +406,83 @@ static struct ast_module *find_resource(const char *resource, int do_lock)
 }
 
 #ifdef LOADABLE_MODULES
+
+/*!
+ * \brief dlclose(), with failure logging.
+ */
+static void logged_dlclose(const char *name, void *lib)
+{
+	if (dlclose(lib) != 0) {
+		ast_log(LOG_WARNING, "Failed to unload %s: %s\n",
+			name, dlerror());
+	}
+}
+
+#if defined(HAVE_RTLD_NOLOAD)
+/*!
+ * \brief Check to see if the given resource is loaded.
+ *
+ * \param resource_name Name of the resource, including .so suffix.
+ * \return False (0) if module is not loaded.
+ * \return True (non-zero) if module is loaded.
+ */
+static int is_module_loaded(const char *resource_name)
+{
+	char fn[PATH_MAX] = "";
+	void *lib;
+
+	ast_verb(10, "Checking if %s is loaded\n", resource_name);
+
+	snprintf(fn, sizeof(fn), "%s/%s", ast_config_AST_MODULE_DIR,
+		resource_name);
+
+	lib = dlopen(fn, RTLD_LAZY | RTLD_NOLOAD);
+
+	if (lib) {
+		ast_verb(10, "  %s loaded\n", resource_name);
+		logged_dlclose(resource_name, lib);
+		return 1;
+	}
+
+	ast_verb(10, "  %s not loaded\n", resource_name);
+	return 0;
+}
+#endif
+
 static void unload_dynamic_module(struct ast_module *mod)
 {
+	char *name = ast_strdupa(ast_module_name(mod));
 	void *lib = mod->lib;
 
 	/* WARNING: the structure pointed to by mod is going to
 	   disappear when this operation succeeds, so we can't
 	   dereference it */
 
-	if (lib)
-		while (!dlclose(lib));
+	if (!lib) {
+		return;
+	}
+
+	logged_dlclose(name, lib);
+
+	/* There are several situations where the module might still be resident
+	 * in memory.
+	 *
+	 * If somehow there was another dlopen() on the same module (unlikely,
+	 * since that all is supposed to happen in loader.c).
+	 *
+	 * Or the lazy resolution of a global symbol (very likely, since that is
+	 * how we load all of our modules that export global symbols).
+	 *
+	 * Avoid the temptation of repeating the dlclose(). The other code that
+	 * dlopened the module still has its module reference, and should close
+	 * it itself. In other situations, dlclose() will happily return success
+	 * for as many times as you wish to call it.
+	 */
+#if defined(HAVE_RTLD_NOLOAD)
+	if (is_module_loaded(name)) {
+		ast_log(LOG_WARNING, "Module '%s' could not be completely unloaded\n", name);
+	}
+#endif
 }
 
 static enum ast_module_load_result load_resource(const char *resource_name, unsigned int global_symbols_only, struct ast_heap *resource_heap, int required);
@@ -461,7 +531,7 @@ static struct ast_module *load_dynamic_module(const char *resource_in, unsigned
 	if (resource_being_loaded != (mod = AST_LIST_LAST(&module_list))) {
 		ast_log(LOG_WARNING, "Module '%s' did not register itself during load\n", resource_in);
 		/* no, it did not, so close it and return */
-		while (!dlclose(lib));
+		logged_dlclose(resource_in, lib);
 		/* note that the module's destructor will call ast_module_unregister(),
 		   which will free the structure we allocated in resource_being_loaded */
 		return NULL;
@@ -472,32 +542,11 @@ static struct ast_module *load_dynamic_module(const char *resource_in, unsigned
 	/* if we are being asked only to load modules that provide global symbols,
 	   and this one does not, then close it and return */
 	if (global_symbols_only && !wants_global) {
-		while (!dlclose(lib));
+		logged_dlclose(resource_in, lib);
 		return NULL;
 	}
 
-	/* This section is a workaround for a gcc 4.1 bug that has already been
-	 * fixed in later versions.  Unfortunately, some distributions, such as
-	 * RHEL/CentOS 5, distribute gcc 4.1, so we're stuck with having to deal
-	 * with this issue.  This basically ensures that optional_api modules are
-	 * loaded before any module which requires their functionality. */
-#if !defined(HAVE_ATTRIBUTE_weak_import) && !defined(HAVE_ATTRIBUTE_weakref)
-	if (!ast_strlen_zero(mod->info->nonoptreq)) {
-		/* Force any required dependencies to load */
-		char *each, *required_resource = ast_strdupa(mod->info->nonoptreq);
-		while ((each = strsep(&required_resource, ","))) {
-			struct ast_module *dependency;
-			each = ast_strip(each);
-			dependency = find_resource(each, 0);
-			/* Is it already loaded? */
-			if (!dependency) {
-				load_resource(each, global_symbols_only, resource_heap, 1);
-			}
-		}
-	}
-#endif
-
-	while (!dlclose(lib));
+	logged_dlclose(resource_in, lib);
 	resource_being_loaded = NULL;
 
 	/* start the load process again */
@@ -523,6 +572,7 @@ static struct ast_module *load_dynamic_module(const char *resource_in, unsigned
 
 	return AST_LIST_LAST(&module_list);
 }
+
 #endif
 
 void ast_module_shutdown(void)
diff --git a/main/optional_api.c b/main/optional_api.c
new file mode 100644
index 000000000..f48fe11a1
--- /dev/null
+++ b/main/optional_api.c
@@ -0,0 +1,365 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2013, Digium, Inc.
+ *
+ * David M. Lee, II <dlee@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/optional_api.h"
+#include "asterisk/utils.h"
+
+#if defined(OPTIONAL_API)
+
+/*
+ * \file Optional API innards.
+ *
+ * The calls to ast_optional_api_*() happen implicitly from \c __constructor__
+ * calls which are defined in header files. This means that some number of them
+ * happen before main() is called. This makes calling most Asterisk APIs
+ * dangerous, since we could be called before they are initialized. This
+ * includes things like AO2, malloc debug, and static mutexes.
+ *
+ * Another limitation is that most functions are called from the midst of
+ * dlopen() or dlclose(), and there is no opportunity to return a failure code.
+ * The best we can do is log an error, and call ast_do_crash().
+ *
+ * Fortunately, there are some constraints that help us out. The \c
+ * ast_optional_api_*() are called during module loads, which happens either
+ * before main(), or during dlopen() calls. These are already serialized, so we
+ * don't have to lock ourselves.
+ */
+
+/*! \brief A user of an optional API */
+struct optional_api_user {
+	/*! Pointer to function pointer to link */
+	ast_optional_fn *optional_ref;
+	/*! Stub to use when impl is unavailable */
+	ast_optional_fn stub;
+	/*! Name of the module using the API */
+	char module[];
+};
+
+/*! \brief An optional API */
+struct optional_api {
+	/*! Pointer to the implementation function; could be null */
+	ast_optional_fn impl;
+	/*! Variable length array of users of this API */
+	struct optional_api_user **users;
+	/*! Allocated size of the \a users array */
+	size_t users_maxlen;
+	/*! Number of entries in the \a users array */
+	size_t users_len;
+	/*! Name of the optional API function */
+	char symname[];
+};
+
+/*!
+ * \brief Free an \ref optional_api_user.
+ *
+ * \param user User struct to free.
+ */
+static void optional_api_user_destroy(struct optional_api_user *user)
+{
+	*user->optional_ref = user->stub;
+	free(user);
+}
+
+/*!
+ * \brief Create an \ref optional_api_user.
+ *
+ * \param optional_ref Pointer-to-function-pointer to link to impl/stub.
+ * \param stub Stub function to link to when impl is not available.
+ * \param module Name of the module requesting the API.
+ *
+ * \return New \ref optional_api_user.
+ * \return \c NULL on error.
+ */
+static struct optional_api_user *optional_api_user_create(
+	ast_optional_fn *optional_ref, ast_optional_fn stub, const char *module)
+{
+	struct optional_api_user *user;
+	size_t size = sizeof(*user) + strlen(module) + 1;
+
+	user = calloc(1, size);
+	if (!user) {
+		return NULL;
+	}
+
+	user->optional_ref = optional_ref;
+	user->stub = stub;
+	strcpy(user->module, module); /* SAFE */
+
+	return user;
+}
+
+/*!
+ * \brief Free an \ref optional_api.
+ *
+ * \param api API struct to free.
+ */
+static void optional_api_destroy(struct optional_api *api)
+{
+	while (api->users_len--) {
+		optional_api_user_destroy(api->users[api->users_len]);
+	}
+	free(api->users);
+	api->users = NULL;
+	api->users_maxlen = 0;
+	free(api);
+}
+
+/*!
+ * \brief Create an \ref optional_api.
+ *
+ * \param symname Name of the optional function.
+ * \return New \ref optional_api.
+ * \return \c NULL on error.
+ */
+static struct optional_api *optional_api_create(const char *symname)
+{
+	struct optional_api *api;
+	size_t size;
+
+	ast_verb(6, "%s: building api object\n", symname);
+	size = sizeof(*api) + strlen(symname) + 1;
+	api = calloc(1, size);
+	if (!api) {
+		ast_log(LOG_ERROR, "Failed to allocate api\n");
+		return NULL;
+	}
+
+	strcpy(api->symname, symname); /* SAFE */
+
+	return api;
+}
+
+/*! Array of \ref optional_api functions */
+struct {
+	/*! Variable length array of API's */
+	struct optional_api **list;
+	/*! Allocated size of the \a list array */
+	size_t maxlen;
+	/*! Number of entries in the \a list array */
+	size_t len;
+} apis;
+
+void optional_api_cleanup(void)
+{
+	while (apis.len--) {
+		optional_api_destroy(apis.list[apis.len]);
+	}
+	free(apis.list);
+	apis.list = NULL;
+	apis.maxlen = 0;
+}
+
+/*!
+ * \brief Gets (or creates) the \ref optional_api for the give function.
+ *
+ * \param sysname Name of the function to look up.
+ * \return Corresponding \ref optional_api.
+ * \return \c NULL on error.
+ */
+static struct optional_api *get_api(const char *symname)
+{
+	struct optional_api *api;
+	size_t i;
+
+	/* Find one, if we already have it */
+	for (i = 0; i < apis.len; ++i) {
+		if (strcmp(symname, apis.list[i]->symname) == 0) {
+			return apis.list[i];
+		}
+	}
+
+	/* API not found. Build one */
+	api = optional_api_create(symname);
+
+	/* Grow the list, if needed */
+	if (apis.len + 1 > apis.maxlen) {
+		size_t new_maxlen = apis.maxlen ? 2 * apis.maxlen : 1;
+		struct optional_api **new_list =
+			realloc(apis.list, new_maxlen * sizeof(*new_list));
+
+		if (!new_list) {
+			optional_api_destroy(api);
+			ast_log(LOG_ERROR, "Failed to allocate api list\n");
+			return NULL;
+		}
+
+		apis.maxlen = new_maxlen;
+		apis.list = new_list;
+	}
+
+	apis.list[apis.len++] = api;
+
+	return api;
+}
+
+/*!
+ * \brief Re-links a given \a user against its associated \a api.
+ *
+ * If the \a api has an implementation, the \a user is linked to that
+ * implementation. Otherwise, the \a user is linked to its \a stub.
+ *
+ * \param user \ref optional_api_user to link.
+ * \param api \ref optional_api to link.
+ */
+static void optional_api_user_relink(struct optional_api_user *user,
+	struct optional_api *api)
+{
+	if (api->impl && *user->optional_ref != api->impl) {
+		ast_verb(4, "%s: linking for %s\n", api->symname, user->module);
+		*user->optional_ref = api->impl;
+	} else if (!api->impl && *user->optional_ref != user->stub) {
+		ast_verb(4, "%s: stubbing for %s\n", api->symname,
+			user->module);
+		*user->optional_ref = user->stub;
+	}
+}
+
+/*!
+ * \brief Sets the implementation function pointer for an \a api.
+ *
+ * \param api API to implement/stub out.
+ * \param impl Pointer to implementation function. Can be 0 to remove
+ *             implementation.
+ */
+static void optional_api_set_impl(struct optional_api *api,
+	ast_optional_fn impl)
+{
+	size_t i;
+
+	api->impl = impl;
+
+	/* re-link all users */
+	for (i = 0; i < api->users_len; ++i) {
+		optional_api_user_relink(api->users[i], api);
+	}
+}
+
+void ast_optional_api_provide(const char *symname, ast_optional_fn impl)
+{
+	struct optional_api *api;
+
+	ast_verb(4, "%s: providing\n", symname);
+
+	api = get_api(symname);
+	if (!api) {
+		ast_log(LOG_ERROR, "%s: Allocation failed\n", symname);
+		ast_do_crash();
+		return;
+	}
+
+	optional_api_set_impl(api, impl);
+}
+
+void ast_optional_api_unprovide(const char *symname, ast_optional_fn impl)
+{
+	struct optional_api *api;
+
+	ast_verb(4, "%s: un-providing\n", symname);
+
+	api = get_api(symname);
+	if (!api) {
+		ast_log(LOG_ERROR, "%s: Could not find api\n", symname);
+		ast_do_crash();
+		return;
+	}
+
+	optional_api_set_impl(api, 0);
+}
+
+void ast_optional_api_use(const char *symname, ast_optional_fn *optional_ref,
+	ast_optional_fn stub, const char *module)
+{
+	struct optional_api_user *user;
+	struct optional_api *api;
+
+
+	api = get_api(symname);
+	if (!api) {
+		ast_log(LOG_ERROR, "%s: Allocation failed\n", symname);
+		ast_do_crash();
+		return;
+	}
+
+	user = optional_api_user_create(optional_ref, stub, module);
+	if (!user) {
+		ast_log(LOG_ERROR, "%s: Allocation failed\n", symname);
+		ast_do_crash();
+		return;
+	}
+
+	/* Add user to the API */
+	if (api->users_len + 1 > api->users_maxlen) {
+		size_t new_maxlen = api->users_maxlen ?
+			2 * api->users_maxlen : 1;
+		struct optional_api_user **new_list =
+			realloc(api->users, new_maxlen * sizeof(*new_list));
+
+		if (!new_list) {
+			optional_api_user_destroy(user);
+			ast_log(LOG_ERROR, "Failed to allocate api list\n");
+			ast_do_crash();
+			return;
+		}
+
+		api->users_maxlen = new_maxlen;
+		api->users = new_list;
+	}
+
+	api->users[api->users_len++] = user;
+
+	optional_api_user_relink(user, api);
+}
+
+void ast_optional_api_unuse(const char *symname, ast_optional_fn *optional_ref,
+	const char *module)
+{
+	struct optional_api *api;
+	size_t i;
+
+	api = get_api(symname);
+	if (!api) {
+		ast_log(LOG_ERROR, "%s: Could not find api\n", symname);
+		ast_do_crash();
+		return;
+	}
+
+	for (i = 0; i < api->users_len; ++i) {
+		struct optional_api_user *user = api->users[i];
+		if (user->optional_ref == optional_ref) {
+			if (*user->optional_ref != user->stub) {
+				ast_verb(4, "%s: stubbing for %s\n", symname,
+					module);
+				*user->optional_ref = user->stub;
+			}
+
+			/* Remove from the list */
+			api->users[i] = api->users[--api->users_len];
+
+			optional_api_user_destroy(user);
+			return;
+		}
+	}
+
+	ast_log(LOG_ERROR, "%s: Could not find user %s\n", symname, module);
+}
+
+#endif /* defined(OPTIONAL_API) */
diff --git a/res/ari/ari_websockets.c b/res/ari/ari_websockets.c
index a34e0f691..20639e12e 100644
--- a/res/ari/ari_websockets.c
+++ b/res/ari/ari_websockets.c
@@ -20,8 +20,10 @@
 
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
-#include "asterisk/astobj2.h"
 #include "asterisk/ari.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/http_websocket.h"
+#include "internal.h"
 
 /*! \file
  *
@@ -163,3 +165,15 @@ int ast_ari_websocket_session_write(struct ast_ari_websocket_session *session,
 	return ast_websocket_write(session->ws_session,
 		AST_WEBSOCKET_OPCODE_TEXT, str,	strlen(str));
 }
+
+void ari_handle_websocket(struct ast_websocket_server *ws_server,
+	struct ast_tcptls_session_instance *ser, const char *uri,
+	enum ast_http_method method, struct ast_variable *get_params,
+	struct ast_variable *headers)
+{
+	struct ast_http_uri fake_urih = {
+		.data = ws_server,
+	};
+	ast_websocket_uri_cb(ser, &fake_urih, uri, method, get_params,
+		headers);
+}
diff --git a/res/ari/internal.h b/res/ari/internal.h
index ffacd4939..8453747f1 100644
--- a/res/ari/internal.h
+++ b/res/ari/internal.h
@@ -25,7 +25,9 @@
  * \author David M. Lee, II <dlee@digium.com>
  */
 
+#include "asterisk/http.h"
 #include "asterisk/json.h"
+#include "asterisk/stringfields.h"
 
 /*! @{ */
 
@@ -139,5 +141,25 @@ struct ast_ari_conf_user *ast_ari_config_validate_user(const char *username,
 
 /*! @} */
 
+/* Forward-declare websocket structs. This avoids including http_websocket.h,
+ * which causes optional_api stuff to happen, which makes optional_api more
+ * difficult to debug. */
+
+struct ast_websocket_server;
+
+/*!
+ * \brief Wrapper for invoking the websocket code for an incoming connection.
+ *
+ * \param ws_server WebSocket server to invoke.
+ * \param ser HTTP session.
+ * \param uri Requested URI.
+ * \param method Requested HTTP method.
+ * \param get_params Parsed query parameters.
+ * \param headers Parsed HTTP headers.
+ */
+void ari_handle_websocket(struct ast_websocket_server *ws_server,
+	struct ast_tcptls_session_instance *ser, const char *uri,
+	enum ast_http_method method, struct ast_variable *get_params,
+	struct ast_variable *headers);
 
 #endif /* ARI_INTERNAL_H_ */
diff --git a/res/res_ari.c b/res/res_ari.c
index 4777bb7c2..5475efce9 100644
--- a/res/res_ari.c
+++ b/res/res_ari.c
@@ -124,11 +124,11 @@
 
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
+#include "ari/internal.h"
+#include "asterisk/ari.h"
 #include "asterisk/astobj2.h"
 #include "asterisk/module.h"
 #include "asterisk/paths.h"
-#include "asterisk/ari.h"
-#include "ari/internal.h"
 
 #include <string.h>
 #include <sys/stat.h>
@@ -522,11 +522,8 @@ void ast_ari_invoke(struct ast_tcptls_session_instance *ser,
 
 	if (handler->ws_server && method == AST_HTTP_GET) {
 		/* WebSocket! */
-		struct ast_http_uri fake_urih = {
-			.data = handler->ws_server,
-		};
-		ast_websocket_uri_cb(ser, &fake_urih, uri, method, get_params,
-			headers);
+		ari_handle_websocket(handler->ws_server, ser, uri, method,
+			get_params, headers);
 		/* Since the WebSocket code handles the connection, we shouldn't
 		 * do anything else; setting no_response */
 		response->no_response = 1;
diff --git a/res/res_ari_events.c b/res/res_ari_events.c
index 567167f14..17337bbc8 100644
--- a/res/res_ari_events.c
+++ b/res/res_ari_events.c
@@ -48,6 +48,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #if defined(AST_DEVMODE)
 #include "ari/ari_model_validators.h"
 #endif
+#include "asterisk/http_websocket.h"
 
 #define MAX_VALS 128
 
diff --git a/res/res_http_websocket.c b/res/res_http_websocket.c
index 129e92c19..b03745e6f 100644
--- a/res/res_http_websocket.c
+++ b/res/res_http_websocket.c
@@ -107,18 +107,24 @@ struct ast_websocket_server {
 	struct ao2_container *protocols; /*!< Container for registered protocols */
 };
 
-static void websocket_server_dtor(void *obj)
+static void websocket_server_internal_dtor(void *obj)
 {
 	struct ast_websocket_server *server = obj;
 	ao2_cleanup(server->protocols);
 	server->protocols = NULL;
 }
 
-struct ast_websocket_server *ast_websocket_server_create(void)
+static void websocket_server_dtor(void *obj)
+{
+	websocket_server_internal_dtor(obj);
+	ast_module_unref(ast_module_info->self);
+}
+
+static struct ast_websocket_server *websocket_server_create_impl(void (*dtor)(void *))
 {
 	RAII_VAR(struct ast_websocket_server *, server, NULL, ao2_cleanup);
 
-	server = ao2_alloc(sizeof(*server), websocket_server_dtor);
+	server = ao2_alloc(sizeof(*server), dtor);
 	if (!server) {
 		return NULL;
 	}
@@ -132,6 +138,17 @@ struct ast_websocket_server *ast_websocket_server_create(void)
 	return server;
 }
 
+static struct ast_websocket_server *websocket_server_internal_create(void)
+{
+	return websocket_server_create_impl(websocket_server_internal_dtor);
+}
+
+struct ast_websocket_server *AST_OPTIONAL_API_NAME(ast_websocket_server_create)(void)
+{
+	ast_module_ref(ast_module_info->self);
+	return websocket_server_create_impl(websocket_server_dtor);
+}
+
 /*! \brief Destructor function for sessions */
 static void session_destroy_fn(void *obj)
 {
@@ -512,7 +529,7 @@ static struct websocket_protocol *one_protocol(
 	return ao2_callback(server->protocols, OBJ_NOLOCK, NULL, NULL);
 }
 
-int ast_websocket_uri_cb(struct ast_tcptls_session_instance *ser, const struct ast_http_uri *urih, const char *uri, enum ast_http_method method, struct ast_variable *get_vars, struct ast_variable *headers)
+int AST_OPTIONAL_API_NAME(ast_websocket_uri_cb)(struct ast_tcptls_session_instance *ser, const struct ast_http_uri *urih, const char *uri, enum ast_http_method method, struct ast_variable *get_vars, struct ast_variable *headers)
 {
 	struct ast_variable *v;
 	char *upgrade = NULL, *key = NULL, *key1 = NULL, *key2 = NULL, *protos = NULL, *requested_protocols = NULL, *protocol = NULL;
@@ -521,6 +538,8 @@ int ast_websocket_uri_cb(struct ast_tcptls_session_instance *ser, const struct a
 	struct ast_websocket *session;
 	struct ast_websocket_server *server;
 
+	SCOPED_MODULE_USE(ast_module_info->self);
+
 	/* Upgrade requests are only permitted on GET methods */
 	if (method != AST_HTTP_GET) {
 		ast_http_error(ser, 501, "Not Implemented", "Attempt to use unimplemented / unsupported method");
@@ -674,7 +693,7 @@ int ast_websocket_uri_cb(struct ast_tcptls_session_instance *ser, const struct a
 }
 
 static struct ast_http_uri websocketuri = {
-	.callback = ast_websocket_uri_cb,
+	.callback = AST_OPTIONAL_API_NAME(ast_websocket_uri_cb),
 	.description = "Asterisk HTTP WebSocket",
 	.uri = "ws",
 	.has_subtree = 0,
@@ -719,7 +738,7 @@ end:
 	ast_websocket_unref(session);
 }
 
-int AST_OPTIONAL_API_NAME(ast_websocket_add_protocol)(const char *name, ast_websocket_callback callback)
+static int websocket_add_protocol_internal(const char *name, ast_websocket_callback callback)
 {
 	struct ast_websocket_server *ws_server = websocketuri.data;
 	if (!ws_server) {
@@ -728,7 +747,16 @@ int AST_OPTIONAL_API_NAME(ast_websocket_add_protocol)(const char *name, ast_webs
 	return ast_websocket_server_add_protocol(ws_server, name, callback);
 }
 
-int AST_OPTIONAL_API_NAME(ast_websocket_remove_protocol)(const char *name, ast_websocket_callback callback)
+int AST_OPTIONAL_API_NAME(ast_websocket_add_protocol)(const char *name, ast_websocket_callback callback)
+{
+	int res = websocket_add_protocol_internal(name, callback);
+	if (res == 0) {
+		ast_module_ref(ast_module_info->self);
+	}
+	return res;
+}
+
+static int websocket_remove_protocol_internal(const char *name, ast_websocket_callback callback)
 {
 	struct ast_websocket_server *ws_server = websocketuri.data;
 	if (!ws_server) {
@@ -737,14 +765,23 @@ int AST_OPTIONAL_API_NAME(ast_websocket_remove_protocol)(const char *name, ast_w
 	return ast_websocket_server_remove_protocol(ws_server, name, callback);
 }
 
+int AST_OPTIONAL_API_NAME(ast_websocket_remove_protocol)(const char *name, ast_websocket_callback callback)
+{
+	int res = websocket_remove_protocol_internal(name, callback);
+	if (res == 0) {
+		ast_module_unref(ast_module_info->self);
+	}
+	return res;
+}
+
 static int load_module(void)
 {
-	websocketuri.data = ast_websocket_server_create();
+	websocketuri.data = websocket_server_internal_create();
 	if (!websocketuri.data) {
 		return AST_MODULE_LOAD_FAILURE;
 	}
 	ast_http_uri_link(&websocketuri);
-	ast_websocket_add_protocol("echo", websocket_echo_callback);
+	websocket_add_protocol_internal("echo", websocket_echo_callback);
 
 	return 0;
 }
diff --git a/rest-api-templates/res_ari_resource.c.mustache b/rest-api-templates/res_ari_resource.c.mustache
index e6b2a88f4..8e043e682 100644
--- a/rest-api-templates/res_ari_resource.c.mustache
+++ b/rest-api-templates/res_ari_resource.c.mustache
@@ -53,6 +53,13 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #if defined(AST_DEVMODE)
 #include "ari/ari_model_validators.h"
 #endif
+{{^has_websocket}}
+{{! Only include http_websocket if necessary. Otherwise we'll do a lot of
+ *  unnecessary optional_api intialization, which makes optional_api harder
+ *  to debug
+ }}
+#include "asterisk/http_websocket.h"
+{{/has_websocket}}
 
 #define MAX_VALS 128
 
diff --git a/rest-api-templates/swagger_model.py b/rest-api-templates/swagger_model.py
index aa065b342..af52266b4 100644
--- a/rest-api-templates/swagger_model.py
+++ b/rest-api-templates/swagger_model.py
@@ -632,6 +632,8 @@ class ApiDeclaration(Stringify):
         api_json = api_decl_json.get('apis') or []
         self.apis = [
             Api().load(j, processor, context) for j in api_json]
+        self.has_websocket = filter(lambda api: api.has_websocket,
+                                    self.apis) == []
         models = api_decl_json.get('models').items() or []
         self.models = [Model().load(id, json, processor, context)
                        for (id, json) in models]
diff --git a/tests/test_optional_api.c b/tests/test_optional_api.c
new file mode 100644
index 000000000..841dd5f86
--- /dev/null
+++ b/tests/test_optional_api.c
@@ -0,0 +1,187 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2013, Digium, Inc.
+ *
+ * David M. Lee, II <dlee@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*!
+ * \file \brief Test optional API.
+ *
+ * This tests exercise the underlying implementation functions. Acutal usage
+ * won't look anything like this; it would use the wrapper macros.
+ *
+ * \author\verbatim David M. Lee, II <dlee@digium.com> \endverbatim
+ *
+ * \ingroup tests
+ */
+
+/*** MODULEINFO
+	<depend>TEST_FRAMEWORK</depend>
+	<depend>OPTIONAL_API</depend>
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/module.h"
+#include "asterisk/optional_api.h"
+#include "asterisk/test.h"
+
+#define CATEGORY "/main/optional_api/"
+
+enum was_called {
+	NONE,
+	STUB,
+	IMPL
+};
+
+enum was_called was_called_result;
+
+ast_optional_fn test_optional_ref;
+
+static void test_optional_stub(void)
+{
+	was_called_result = STUB;
+}
+
+static void test_optional_impl(void)
+{
+	was_called_result = IMPL;
+}
+
+static void test_optional(void)
+{
+	was_called_result = NONE;
+	if (test_optional_ref) {
+		test_optional_ref();
+	}
+}
+
+#define SYMNAME "test_option"
+
+AST_TEST_DEFINE(test_provide_first)
+{
+	enum ast_test_result_state res;
+
+	switch (cmd) {
+	case TEST_INIT:
+		info->name = __func__;
+		info->category = CATEGORY;
+		info->summary = "Test optional API publishing.";
+		info->description = "Test optional API publishing.";
+		return AST_TEST_NOT_RUN;
+	case TEST_EXECUTE:
+		break;
+	}
+
+	res = AST_TEST_FAIL;
+	test_optional_ref = 0;
+
+	ast_optional_api_provide(SYMNAME, test_optional_impl);
+
+	ast_optional_api_use(SYMNAME, &test_optional_ref, test_optional_stub,
+		AST_MODULE);
+
+	test_optional();
+
+	if (was_called_result != IMPL) {
+		ast_test_status_update(test, "Expected %d, was %d",
+			IMPL, was_called_result);
+		goto done;
+	}
+
+	res = AST_TEST_PASS;
+
+ done:
+	ast_optional_api_unuse(SYMNAME, &test_optional_ref, AST_MODULE);
+	ast_optional_api_unprovide(SYMNAME, test_optional_impl);
+	return res;
+}
+
+AST_TEST_DEFINE(test_provide_last)
+{
+	enum ast_test_result_state res;
+
+	switch (cmd) {
+	case TEST_INIT:
+		info->name = __func__;
+		info->category = CATEGORY;
+		info->summary = "Test optional API publishing.";
+		info->description = "Test optional API publishing.";
+		return AST_TEST_NOT_RUN;
+	case TEST_EXECUTE:
+		break;
+	}
+
+	res = AST_TEST_FAIL;
+	test_optional_ref = 0;
+
+	ast_optional_api_use(SYMNAME, &test_optional_ref, test_optional_stub,
+		AST_MODULE);
+
+	test_optional();
+	if (was_called_result != STUB) {
+		ast_test_status_update(test, "Expected %d, was %d",
+			STUB, was_called_result);
+		goto done;
+	}
+
+	ast_optional_api_provide(SYMNAME, test_optional_impl);
+
+	test_optional();
+	if (was_called_result != IMPL) {
+		ast_test_status_update(test, "Expected %d, was %d",
+			IMPL, was_called_result);
+		ast_optional_api_unprovide(SYMNAME, test_optional_impl);
+		goto done;
+	}
+
+	ast_optional_api_unprovide(SYMNAME, test_optional_impl);
+
+	test_optional();
+	if (was_called_result != STUB) {
+		ast_test_status_update(test, "Expected %d, was %d",
+			STUB, was_called_result);
+		ast_optional_api_unprovide(SYMNAME, test_optional_impl);
+		goto done;
+	}
+
+	res = AST_TEST_PASS;
+
+ done:
+	ast_optional_api_unuse(SYMNAME, &test_optional_ref, AST_MODULE);
+	return res;
+}
+
+static int unload_module(void)
+{
+	AST_TEST_UNREGISTER(test_provide_first);
+	AST_TEST_UNREGISTER(test_provide_last);
+	return 0;
+}
+
+static int load_module(void)
+{
+	AST_TEST_REGISTER(test_provide_first);
+	AST_TEST_REGISTER(test_provide_last);
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "ARI testing",
+	.load = load_module,
+	.unload = unload_module,
+	);