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  • /*
     * Asterisk -- An open source telephony toolkit.
     *
     * Copyright (C) 2010, Digium, Inc.
     *
     * David Vossel <dvossel@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 FrameHooks Architecture
     *
     * \author David Vossel <dvossel@digium.com>
     */
    
    
    /*** MODULEINFO
    	<support_level>core</support_level>
     ***/
    
    
    #include "asterisk.h"
    
    ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
    
    #include "asterisk/channel.h"
    #include "asterisk/linkedlists.h"
    #include "asterisk/framehook.h"
    #include "asterisk/frame.h"
    
    struct ast_framehook {
    	struct ast_framehook_interface i;
    	/*! This pointer to ast_channel the framehook is attached to. */
    	struct ast_channel *chan;
    	/*! the id representing this framehook on a channel */
    	unsigned int id;
    	/*! when set, this signals the read and write function to detach the hook */
    	int detach_and_destroy_me;
    	/*! list entry for ast_framehook_list object */
    	AST_LIST_ENTRY(ast_framehook) list;
    };
    
    struct ast_framehook_list {
    
    	/*! the number of hooks currently present */
    	unsigned int count;
    	/*! id for next framehook added */
    
    	unsigned int id_count;
    	AST_LIST_HEAD_NOLOCK(, ast_framehook) list;
    };
    
    
    enum framehook_detachment_mode
    {
    	/*! Destroy the framehook outright. */
    	FRAMEHOOK_DETACH_DESTROY = 0,
    	/*! Remove the framehook from the channel, but don't destroy the data since
    	 *  it will be used by a replacement framehook on another channel. */
    	FRAMEHOOK_DETACH_PRESERVE,
    };
    
    static void framehook_detach(struct ast_framehook *framehook, enum framehook_detachment_mode mode)
    
    {
    	struct ast_frame *frame;
    	frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_DETACHED, framehook->i.data);
    	/* never assume anything about this function. If you can return a frame during
    	 * the detached event, then assume someone will. */
    	if (frame) {
    		ast_frfree(frame);
    	}
    	framehook->chan = NULL;
    
    
    	if (mode == FRAMEHOOK_DETACH_DESTROY && framehook->i.destroy_cb) {
    
    		framehook->i.destroy_cb(framehook->i.data);
    	}
    	ast_free(framehook);
    }
    
    static struct ast_frame *framehook_list_push_event(struct ast_framehook_list *framehooks, struct ast_frame *frame, enum ast_framehook_event event)
    {
    	struct ast_framehook *framehook;
    
    	struct ast_frame *original_frame;
    	int *skip;
    	size_t skip_size;
    
    
    	if (!framehooks) {
    		return frame;
    	}
    
    
    	skip_size = sizeof(int) * framehooks->count;
    
    	memset(skip, 0, skip_size);
    
    	do {
    		unsigned int num = 0;
    		original_frame = frame;
    
    		AST_LIST_TRAVERSE_SAFE_BEGIN(&framehooks->list, framehook, list) {
    			if (framehook->detach_and_destroy_me) {
    				/* this guy is signaled for destruction */
    				AST_LIST_REMOVE_CURRENT(list);
    
    				framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
    
    				continue;
    			}
    
    			/* If this framehook has been marked as needing to be skipped, do so */
    			if (skip[num]) {
    				num++;
    				continue;
    			}
    
    
    			frame = framehook->i.event_cb(framehook->chan, frame, event, framehook->i.data);
    
    
    			if (frame != original_frame) {
    				/* To prevent looping we skip any framehooks that have already provided a modified frame */
    				skip[num] = 1;
    				break;
    			}
    
    			num++;
    
    		AST_LIST_TRAVERSE_SAFE_END;
    	} while (frame != original_frame);
    
    
    	return frame;
    }
    
    int ast_framehook_attach(struct ast_channel *chan, struct ast_framehook_interface *i)
    {
    	struct ast_framehook *framehook;
    
    	struct ast_framehook_list *fh_list;
    
    	struct ast_frame *frame;
    	if (i->version != AST_FRAMEHOOK_INTERFACE_VERSION) {
    
    		ast_log(LOG_ERROR, "Version '%hu' of framehook interface not what we compiled against (%i)\n",
    
    			i->version, AST_FRAMEHOOK_INTERFACE_VERSION);
    		return -1;
    	}
    	if (!i->event_cb || !(framehook = ast_calloc(1, sizeof(*framehook)))) {
    		return -1;
    	}
    	framehook->i = *i;
    	framehook->chan = chan;
    
    	/* create the framehook list if it didn't already exist */
    
    	if (!ast_channel_framehooks(chan)) {
    		if (!(fh_list = ast_calloc(1, sizeof(*ast_channel_framehooks(chan))))) {
    			ast_free(framehook);
    			return -1;
    		}
    		ast_channel_framehooks_set(chan, fh_list);
    
    	ast_channel_framehooks(chan)->count++;
    
    	framehook->id = ++ast_channel_framehooks(chan)->id_count;
    	AST_LIST_INSERT_TAIL(&ast_channel_framehooks(chan)->list, framehook, list);
    
    
    	/* Tell the event callback we're live and rocking */
    	frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_ATTACHED, framehook->i.data);
    
    	/* Never assume anything about this function. If you can return a frame during
    	 * the attached event, then assume someone will. */
    	if (frame) {
    		ast_frfree(frame);
    	}
    
    
    		ast_channel_set_unbridged_nolock(chan, 1);
    
    	return framehook->id;
    }
    
    int ast_framehook_detach(struct ast_channel *chan, int id)
    {
    	struct ast_framehook *framehook;
    	int res = -1;
    
    
    	if (!ast_channel_framehooks(chan)) {
    
    	AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
    
    		if (framehook->id == id) {
    			/* we mark for detachment rather than doing explicitly here because
    			 * it needs to be safe for this function to be called within the
    			 * event callback.  If we allowed the hook to actually be destroyed
    			 * immediately here, the event callback would crash on exit. */
    			framehook->detach_and_destroy_me = 1;
    			res = 0;
    			break;
    		}
    	}
    	AST_LIST_TRAVERSE_SAFE_END;
    
    
    	if (!res && ast_channel_is_bridged(chan)) {
    
    		ast_channel_set_unbridged_nolock(chan, 1);
    
    	return res;
    }
    
    int ast_framehook_list_destroy(struct ast_channel *chan)
    {
    	struct ast_framehook *framehook;
    
    
    	if (!ast_channel_framehooks(chan)) {
    
    	AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
    
    		AST_LIST_REMOVE_CURRENT(list);
    
    		framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
    
    	}
    	AST_LIST_TRAVERSE_SAFE_END;
    
    	ast_free(ast_channel_framehooks(chan));
    	ast_channel_framehooks_set(chan, NULL);
    
    void ast_framehook_list_fixup(struct ast_channel *old_chan, struct ast_channel *new_chan)
    {
    	struct ast_framehook *framehook;
    	int moved_framehook_id;
    
    
    	if (ast_channel_framehooks(new_chan)) {
    		AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(new_chan)->list, framehook, list) {
    			if (framehook->i.disable_inheritance) {
    				ast_framehook_detach(new_chan, framehook->id);
    				continue;
    			}
    
    			if (framehook->i.chan_breakdown_cb) {
    				framehook->i.chan_breakdown_cb(framehook->i.data, framehook->id,
    					old_chan, new_chan);
    			}
    		}
    		AST_LIST_TRAVERSE_SAFE_END;
    	}
    
    
    	if (!ast_channel_framehooks(old_chan)) {
    		return;
    	}
    
    
    	if (!AST_LIST_EMPTY(&ast_channel_framehooks(old_chan)->list)
    		&& ast_channel_is_bridged(old_chan)) {
    		ast_channel_set_unbridged_nolock(old_chan, 1);
    	}
    	while ((framehook = AST_LIST_REMOVE_HEAD(&ast_channel_framehooks(old_chan)->list, list))) {
    
    		/* If inheritance is not allowed for this framehook, just destroy it. */
    		if (framehook->i.disable_inheritance) {
    			framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
    			continue;
    		}
    
    		/* Otherwise move it to the other channel and perform any fixups set by the framehook interface */
    		moved_framehook_id = ast_framehook_attach(new_chan, &framehook->i);
    		if (moved_framehook_id < 0) {
    			ast_log(LOG_WARNING, "Failed framehook copy during masquerade. Expect loss of features.\n");
    			framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
    		} else {
    			if (framehook->i.chan_fixup_cb) {
    				framehook->i.chan_fixup_cb(framehook->i.data, moved_framehook_id,
    					old_chan, new_chan);
    			}
    
    			framehook_detach(framehook, FRAMEHOOK_DETACH_PRESERVE);
    		}
    	}
    }
    
    
    int ast_framehook_list_is_empty(struct ast_framehook_list *framehooks)
    {
    	if (!framehooks) {
    		return 1;
    	}
    	return AST_LIST_EMPTY(&framehooks->list) ? 1 : 0;
    }
    
    
    int ast_framehook_list_contains_no_active(struct ast_framehook_list *framehooks)
    
    {
    	return ast_framehook_list_contains_no_active_of_type(framehooks, 0);
    }
    
    int ast_framehook_list_contains_no_active_of_type(struct ast_framehook_list *framehooks,
    	enum ast_frame_type type)
    
    {
    	struct ast_framehook *cur;
    
    	if (!framehooks) {
    		return 1;
    	}
    
    	if (AST_LIST_EMPTY(&framehooks->list)) {
    		return 1;
    	}
    
    	AST_LIST_TRAVERSE(&framehooks->list, cur, list) {
    		if (cur->detach_and_destroy_me) {
    			continue;
    		}
    
    		if (type && cur->i.consume_cb && !cur->i.consume_cb(cur->i.data, type)) {
    			continue;
    		}
    
    struct ast_frame *ast_framehook_list_write_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
    {
    	return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_WRITE);
    }
    
    struct ast_frame *ast_framehook_list_read_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
    {
    	return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_READ);
    }