freeswitch 内核模块开发

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这里以模块 helloworld 为例。

1. 创建模块目录  freeswitch/src/mod/applications/mod_helloworld

2. 把模块名放在 freeswitch/modules.conf文件中，make时 根据此文件选择编译哪些模块并生成相应模块的makefile文件

3. 如果你的模块以依赖第三方库，则需要在makefile中指定头文件以及库的路径，一个例子：

LOCAL_CFLAGS=-I$(switch_srcdir)/libs/libteletone/src
LOCAL_LDFLAGS=$(switch_srcdir)/libs/libteletone/libteletone.la

4.如果你的模块包含多个文件则需要 指定文件列表：

LOCAL_OBJS=file.c file2.c file3.c
local_depend: $(LOCAL_OBJS)

5.编写模块接口

freeswitch中 每个模块从加载->运行->关闭 流程由三个宏实现，实际编写模块过程为几个宏的填写。具体业务逻辑在宏内部实现。

SWITCH_MODULE_LOAD_FUNCTION (mod_name)

实际展开即为函数，load function 负责系统启动时或运行时加载模块，模块的全局数据结构，钩子设置，事件handler 一般在此处实现。

SWITCH_MODULE_RUNTIME_FUNCTION

系统运行时loop, 这里可以启动线程处理请求，监听socket 等等。

SWITCH_MODULE_SHUTDOWN_FUNCTION

模块卸载，这里负责清除全局数据结构，释放资源。
  

SWITCH_MODULE_DEFINITION  模块的定义

mod_helloworld.c 代码：

#include <switch.h>

/*  initialize any global structures, hook up any event or state handlers ,etc  */
SWITCH_MODULE_LOAD_FUNCTION(mod_helloworld_load);

/*  the runtime loop of the module, from here you can listen on sockets,
*  spawn new threads to handle requests. etc.
*/
SWITCH_MODULE_RUNTIME_FUNCTION(mod_helloworld_runtime);

/*
*   This is where you do any cleanup for unloading or reloading the module,
*     you should release state handlers, event reservations, etc.
*      You should also synchronize with shutting down the runtime thread (usually using something like a shared 'running' variable that the shutdown function
*    sets to some value that the runtime function notices, sets to a third value and then exits).
*/
SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_helloworld_shutdown);

SWITCH_MODULE_DEFINITION(mod_helloworld, mod_helloworld_load, mod_helloworld_shutdown, NULL);

SWITCH_STANDARD_API(helloworld_function)
{
return SWITCH_STATUS_SUCCESS;
}
static switch_status_t parse_config(switch_bool_t reload)
{
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "parse config\n");

return SWITCH_STATUS_SUCCESS;
}

/*
Macro expands to: switch_status_t  mod_helloworld_load(switch_loadable_module_interface_t **module_interface,
switch_memory_pool_t *pool)
*/
SWITCH_MODULE_LOAD_FUNCTION(mod_helloworld_load)
{
switch_api_interface_t *api_interface;
/* connect my internal structure to the blank pointer passed to me */
*module_interface = switch_loadable_module_create_module_interface(pool, modname);

switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "Hello World!\n");

parse_config(SWITCH_FALSE);

SWITCH_ADD_API(api_interface, "helloworld", "Hello World API", helloworld_function, "syntax");

/* indicate that the module should continue to be loaded */
return SWITCH_STATUS_SUCCESS;

}

SWITCH_MODULE_RUNTIME_FUNCTION(mod_helloworld_runtime)
{
while(1) {
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "Hello World!\n");
switch_yield(10000);
}
}

编译： sudo make mod_helloworld
安装   sudo make mod_helloworld-install
dialplan里试一试 function  helloworld.
-----------------------------------
高级：
1.模块加载函数内可以加载自定义xml配置文件.
例子：
<configuration name="mymodule.conf" description="MyModule configuration">
<settings>
<param name="key" value="value"/>
...
</settings>
</configuration>
You could do the following:

switch_xml_t xml = NULL, x_lists = NULL, x_list = NULL, cfg = NULL;
if ((xml = switch_xml_open_cfg("mymodule.conf", &cfg, NULL))) {
if ((x_lists = switch_xml_child(cfg, "settings"))) {
for (x_list = switch_xml_child(x_lists, "param"); x_list; x_list = x_list->next) {
const char *name = switch_xml_attr(x_list, "name"); // This needs to be const
const char *value = switch_xml_attr(x_list, "value");

// Ignore empty/missing attributes
if (switch_strlen_zero(name)) {
continue;
}

if (switch_strlen_zero(value)) {
continue;
}

if (!strcmp(name, "myattribute")) {
// Do something with value
} else if (!strcmp(name, "myotherattribute")) {
// ...
} else {
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Unknown attribute %s\n", name);
}
}
}
} else {
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Failed to load MyModule's config!\n");
}

2. 订阅事件
模块可以向系统订阅自己感兴趣的事件，只需一个函数，指定一个你自己的事件回调。
例子：订阅所有事件
if (switch_event_bind("mod_mymodule", SWITCH_EVENT_ALL, SWITCH_EVENT_SUBCLASS_ANY, mymodule_event_handler, NULL) != SWITCH_STATUS_SUCCESS) {
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Cannot bind to event handler!\n");
}

接下来就是编写你的回调函数
void mymodule_event_handler(switch_event_t *event);
void mymodule_event_handler(switch_event_t *event)
{
switch_assert(event); // Just a sanity check

switch(event->event_id) {
case SWITCH_EVENT_CHANNEL_CREATE:
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "A new channel is born, its called \"%s\"\n",
switch_event_get_header_nil(event, "channel-name")); // This function isnt case-sensitive
break;
case SWITCH_EVENT_CHANNEL_DESTROY:
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "A channel named \"%s\" has been destroyed\n"
switch_event_get_header_nil(event, "channel-name"));
break;
}
}

3.在模块内 发起呼叫，定义channle状态回调。。。。