PJSIP学习笔记——从simple_pjsua.c示例程序了解PJSUA-LIB的基本使用流程

pjsip的整体框架图贴到这里



要了解pjsip的使用，simple_pjsua.c是一个很好的例子，虽然代码只有短短的172行，却展示了pjsua-lib层的完整使用流程、注册流程和基本呼叫流程。

下面是学习过程中整理的simple_pjsua.c中的main函数主要流程：



先来看看pjsip-apps/src/samples/simple_pjsua.c的源代码

来电的回调函数

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//来电回调函数

/* Callback called by the library upon receiving incoming call */

static void on_incoming_call(pjsua_acc_id acc_id, pjsua_call_id call_id,

pjsip_rx_data *rdata)

{

pjsua_call_info ci;



PJ_UNUSED_ARG(acc_id);

PJ_UNUSED_ARG(rdata);



// 获得呼叫信息

pjsua_call_get_info(call_id, &ci);



PJ_LOG(3,(THIS_FILE, "Incoming call from %.*s!!",

(int)ci.remote_info.slen,

ci.remote_info.ptr));



// 自动应答呼叫

/* Automatically answer incoming calls with 200/OK */

pjsua_call_answer(call_id, 200, NULL, NULL);

}

呼叫状态改变的回调函数，没有做实质性的操作：

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//呼叫状态改变的回调函数

/* Callback called by the library when call's state has changed */

static void on_call_state(pjsua_call_id call_id, pjsip_event *e)

{

pjsua_call_info ci;



PJ_UNUSED_ARG(e);



pjsua_call_get_info(call_id, &ci);

PJ_LOG(3,(THIS_FILE, "Call %d state=%.*s", call_id,

(int)ci.state_text.slen,

ci.state_text.ptr));

}

媒体状态改变的回调函数：

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//媒体状态改变的回调函数

/* Callback called by the library when call's media state has changed */

static void on_call_media_state(pjsua_call_id call_id)

{

pjsua_call_info ci;



pjsua_call_get_info(call_id, &ci);



// 当媒体为激活时，连接呼叫和声音设备

if (ci.media_status == PJSUA_CALL_MEDIA_ACTIVE) {

// When media is active, connect call to sound device.

pjsua_conf_connect(ci.conf_slot, 0);

pjsua_conf_connect(0, ci.conf_slot);

}

}

error_exit退出函数：

//显示错误以及退出应用函数

/* Display error and exit application */

static void error_exit(const char *title, pj_status_t status)

{

pjsua_perror(THIS_FILE, title, status);

pjsua_destroy();

exit(1);

}

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/*

* main()

*

* argv[1] may contain URL to call.

*/

int main(int argc, char *argv[])

{

pjsua_acc_id acc_id;

pj_status_t status;



// 创建PJSIP

/* Create pjsua first! */

status = pjsua_create();

if (status != PJ_SUCCESS) error_exit("Error in pjsua_create()", status);



// 校验被叫SIP地址是否正确

/* If argument is specified, it's got to be a valid SIP URL */

if (argc > 1) {

status = pjsua_verify_url(argv[1]);

if (status != PJ_SUCCESS) error_exit("Invalid URL in argv", status);

}



// 初始化PJSUA，设置回调函数

/* Init pjsua */

{

pjsua_config cfg;

pjsua_logging_config log_cfg;



pjsua_config_default(&cfg);

cfg.cb.on_incoming_call = &on_incoming_call;

cfg.cb.on_call_media_state = &on_call_media_state;

cfg.cb.on_call_state = &on_call_state;



pjsua_logging_config_default(&log_cfg);

log_cfg.console_level = 4;



status = pjsua_init(&cfg, &log_cfg, NULL);

if (status != PJ_SUCCESS) error_exit("Error in pjsua_init()", status);

}



// 创建PJSIP的传输端口

/* Add UDP transport. */

{

pjsua_transport_config cfg;



pjsua_transport_config_default(&cfg);

cfg.port = 5060;

status = pjsua_transport_create(PJSIP_TRANSPORT_UDP, &cfg, NULL);

if (status != PJ_SUCCESS) error_exit("Error creating transport", status);

}



// 启动PJSIP

/* Initialization is done, now start pjsua */

status = pjsua_start();

if (status != PJ_SUCCESS) error_exit("Error starting pjsua", status);



// 设置SIP用户帐号

/* Register to SIP server by creating SIP account. */

{

pjsua_acc_config cfg;



pjsua_acc_config_default(&cfg);

cfg.id = pj_str("sip:" SIP_USER "@" SIP_DOMAIN);

cfg.reg_uri = pj_str("sip:" SIP_DOMAIN);

cfg.cred_count = 1;

cfg.cred_info[0].realm = pj_str(SIP_DOMAIN);

cfg.cred_info[0].scheme = pj_str("digest");

cfg.cred_info[0].username = pj_str(SIP_USER);

cfg.cred_info[0].data_type = PJSIP_CRED_DATA_PLAIN_PASSWD;

cfg.cred_info[0].data = pj_str(SIP_PASSWD);



status = pjsua_acc_add(&cfg, PJ_TRUE, &acc_id);

if (status != PJ_SUCCESS) error_exit("Error adding account", status);

}



// 发起一个呼叫

/* If URL is specified, make call to the URL. */

if (argc > 1) {

pj_str_t uri = pj_str(argv[1]);

status = pjsua_call_make_call(acc_id, &uri, 0, NULL, NULL, NULL);

if (status != PJ_SUCCESS) error_exit("Error making call", status);

}



// 循环等待

/* Wait until user press "q" to quit. */

for (;;) {

char option[10];



puts("Press 'h' to hangup all calls, 'q' to quit");

if (fgets(option, sizeof(option), stdin) == NULL) {

puts("EOF while reading stdin, will quit now..");

break;

}



if (option[0] == 'q')

break;



if (option[0] == 'h')

pjsua_call_hangup_all();

}



/* Destroy pjsua */

pjsua_destroy();



return 0;

}

我们这里可以分析一下它的代码：

1、一开始是回调使用的函数，例如on_incoming_call当来电话的时候，pjsip会自动去调用你写的这个函数，前提是你在初始化pjsua的时候设置了on_incoming_call = &on_incoming_call，

2、error_exit退出应用所需要的操作

3、main函数：

(1)pjsua_create()创建pjsua的第一步，如果是要打电话要确认URL是否是正确的pjsua_verify_url

(2)初始化pjsua，pjsua_config_default(&cfg)来初始化配置，然后设置一些回调函数，设置日志，最后初始化pjsua_init(&cfg, &log_cfg, NULL);

(3)创建UDP的传输，设置端口号

(4)接下来就是启动pjsua，通过pjsua_start();

(5)创建账户，这个是这篇文章的主要内容，pjsua_acc_config_default初始化配置，然后设置相关的内容，id对应这url，realm是服务器的域名，还有密码和用户名，最后调用 pjsua_acc_add(&cfg, PJ_TRUE, &acc_id);来实现帐号的注册。

4、打电话，上面也提到过，你打电话的话需要验证URL是否正确的 pjsua_verify_url，然后调用pjsua_call_make_call来打电话。

5、挂电话，调用 pjsua_call_hangup_all();

6、最后销毁，pjsua_destroy();