freeswitch 内核模块开发

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 /* 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.

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高级：

1.模块加载函数内可以加载自定义xml配置文件.

例子：

... 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。。。。