Decouple subscription handling from NOTIFY/PUBLISH body generation.

When the PJSIP pubsub framework was created, subscription handlers were required
to state what event they handled along with what body types they knew how to
generate. While this serves well when implementing a base RFC, it has problems
when trying to extend the body to support non-standard or proprietary body
elements. The code also was NOTIFY-specific, meaning that when the time comes
that we start writing code to send out PUBLISH requests with MWI or presence
bodies, we would likely find ourselves duplicating code that had previously been
written.

This changeset introduces the concept of body generators and body supplements. A
body generator is responsible for allocating a native structure for a given body
type, providing the primary body content, converting the native structure to a
string, and deallocating resources. A body supplement takes the primary body
content (the native structure, not a string) generated by the body generator and
adds nonstandard elements to the body. With these elements living in their own
module, it becomes easy to extend our support for body types and to re-use
resources when sending a PUBLISH request.

Body generators and body supplements register themselves with the pubsub core,
similar to how subscription and publish handlers had done. Now, subscription
handlers do not need to know what type of body content they generate, but they
still need to inform the pubsub core about what the default body type for a
given event package is. The pubsub core keeps track of what body generators and
body supplements have been registered. When a SUBSCRIBE arrives, the pubsub core
will check that there is a subscription handler for the event in the SUBSCRIBE,
then it will check that there is a body generator that can provide the content
specified in the Accept header(s).

Because of the nature of body generators and supplements, it means
res_pjsip_exten_state and res_pjsip_mwi have been completely gutted. They no
longer worry about body types, instead calling
ast_sip_pubsub_generate_body_content() when they need to generate a NOTIFY body.

Review: https://reviewboard.asterisk.org/r/3150
........

Merged revisions 407016 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@407030 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 112 insertions, 0 deletions

diff --git a/res/res_pjsip_mwi_body_generator.c b/res/res_pjsip_mwi_body_generator.c
new file mode 100644
index 000000000..9a721dbf4
--- /dev/null
+++ b/res/res_pjsip_mwi_body_generator.c
@@ -0,0 +1,112 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2014, Digium, Inc.
+ *
+ * Mark Michelson <mmichelson@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.
+ */
+
+/*** MODULEINFO
+	<depend>pjproject</depend>
+	<depend>res_pjsip</depend>
+	<depend>res_pjsip_pubsub</depend>
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+#include <pjsip.h>
+#include <pjsip_simple.h>
+#include <pjlib.h>
+
+#include "asterisk/res_pjsip.h"
+#include "asterisk/res_pjsip_pubsub.h"
+#include "asterisk/res_pjsip_body_generator_types.h"
+#include "asterisk/module.h"
+#include "asterisk/strings.h"
+
+#define MWI_TYPE "application"
+#define MWI_SUBTYPE "simple-message-summary"
+
+static void *mwi_allocate_body(void *data)
+{
+	struct ast_str **mwi_str;
+
+	mwi_str = ast_malloc(sizeof(*mwi_str));
+	if (!mwi_str) {
+		return NULL;
+	}
+	*mwi_str = ast_str_create(64);
+	if (!*mwi_str) {
+		ast_free(mwi_str);
+		return NULL;
+	}
+	return mwi_str;
+}
+
+static int mwi_generate_body_content(void *body, void *data)
+{
+	struct ast_str **mwi = body;
+	struct ast_sip_message_accumulator *counter = data;
+
+	ast_str_append(mwi, 0, "Messages-Waiting: %s\r\n",
+			counter->new_msgs ? "yes" : "no");
+	ast_str_append(mwi, 0, "Voice-Message: %d/%d (0/0)\r\n",
+			counter->new_msgs, counter->old_msgs);
+
+	return 0;
+}
+
+static void mwi_to_string(void *body, struct ast_str **str)
+{
+	struct ast_str **mwi = body;
+
+	ast_str_set(str, 0, "%s", ast_str_buffer(*mwi));
+}
+
+static void mwi_destroy_body(void *body)
+{
+	struct ast_str **mwi = body;
+
+	ast_free(*mwi);
+	ast_free(mwi);
+}
+
+static struct ast_sip_pubsub_body_generator mwi_generator = {
+	.type = MWI_TYPE,
+	.subtype = MWI_SUBTYPE,
+	.allocate_body = mwi_allocate_body,
+	.generate_body_content = mwi_generate_body_content,
+	.to_string = mwi_to_string,
+	.destroy_body = mwi_destroy_body,
+};
+
+static int load_module(void)
+{
+	if (ast_sip_pubsub_register_body_generator(&mwi_generator)) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+	ast_sip_pubsub_unregister_body_generator(&mwi_generator);
+	return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP MWI resource",
+		.load = load_module,
+		.unload = unload_module,
+		.load_pri = AST_MODPRI_CHANNEL_DEPEND,
+);