iOS：PJSIP 后台 30-40 秒后无来电

Question

我的 voip 应用程序有问题。我正在使用 PJSIP 2.4.5（这是最新版本），当我的应用程序进入后台时出现问题。一切正常 30-40 秒，然后我无法接听来电，直到应用程序回到前台。我已经搜索了很多，但我没有找到解决我的问题的方法。

这是我的代码，我在其中初始化 PJSIP

static pjsua_acc_id acc_id;
static pjsua_call_id incoming_call_id;
static pjsua_call_id current_call_id;
int imcalling=1; //this variable tell the program if I'm currently calling

const size_t MAX_SIP_ID_LENGTH = 50;
const size_t MAX_SIP_REG_URI_LENGTH = 50;

static void on_incoming_call(pjsua_acc_id acc_id, pjsua_call_id call_id, pjsip_rx_data *rdata);
static void on_call_state(pjsua_call_id call_id, pjsip_event *e);
static void on_call_media_state(pjsua_call_id call_id);
static void error_exit(const char *title, pj_status_t status);

//pointers for the callbacks to objective-c
void (*callee_response)();
void (*callee_hangup)(int);
void (*call_incoming)(char*);
void (*call_incoming_canceled)(char*);
void (*call_get_statistics)(char*);

int startPjsip(const char *sipUser, const char *sipPassword, const char* sipDomain, const char* realm, unsigned int reg_timeout, int transport_protocol, void(*incoming_call)(char*), void(*incoming_call_cancel)(char*), void(*get_call_statistics)(char*))
{
pj_status_t status;

pjsip_cfg_t *mysipcfg = pjsip_cfg();
mysipcfg->tcp.keep_alive_interval = 20;

// Create pjsua first
status = pjsua_create();
if (status != PJ_SUCCESS) error_exit("Error in pjsua_create()", status);

// Init pjsua
{
    // Init the config structure
    pjsua_config 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;

    // Init the logging config structure
    pjsua_logging_config log_cfg;
    pjsua_logging_config_default(&log_cfg);
    log_cfg.console_level = 4;

    // Init the pjsua
    status = pjsua_init(&cfg, &log_cfg, NULL);
    if (status != PJ_SUCCESS) error_exit("Error in pjsua_init()", status);
}

// Add UDP transport.
{
    // Init transport config structure
    pjsua_transport_config cfg;
    pjsua_transport_config_default(&cfg);
    cfg.port = 5060;

    // Add UDP transport.
    status = pjsua_transport_create(PJSIP_TRANSPORT_UDP, &cfg, NULL);
    if (status != PJ_SUCCESS) error_exit("Error creating transport", status);
}

// Add TCP transport.
{
    // Init transport config structure
    pjsua_transport_config cfg;
    pjsua_transport_config_default(&cfg);

    cfg.port = 5060;

    // Add TCP transport.
    status = pjsua_transport_create(PJSIP_TRANSPORT_TCP, &cfg, NULL);
    if (status != PJ_SUCCESS) error_exit("Error creating transport", status);
}

// Initialization is done, now start pjsua
status = pjsua_start();
if (status != PJ_SUCCESS) error_exit("Error starting pjsua", status);

call_incoming=incoming_call;  //pointer to the function that will tell to the app that a call is incoming
call_incoming_canceled=incoming_call_cancel;  //pointer to the function that will tell to the app that a call is canceled
call_get_statistics=get_call_statistics;  //pointer to the function that send the call statistics to the app

// Register the account on sip server
{
    pjsua_acc_config cfg;

    pjsua_acc_config_default(&cfg);

    char sipId[MAX_SIP_ID_LENGTH];
    sprintf(sipId, "sip:%s@%s", sipUser, sipDomain);
    cfg.id = pj_str(sipId);

    char regUri[MAX_SIP_REG_URI_LENGTH];
    if(transport_protocol==1) sprintf(regUri, "sip:%s;transport=tcp", sipDomain);
    else sprintf(regUri, "sip:%s", sipDomain);
    cfg.reg_uri = pj_str(regUri);

    cfg.reg_timeout = reg_timeout;
    //cfg.ka_interval = 30;

    cfg.cred_count = 1;
    cfg.cred_info[0].realm = pj_str((char*)realm);
    cfg.cred_info[0].scheme = pj_str("digest");
    cfg.cred_info[0].username = pj_str((char*)sipUser);
    cfg.cred_info[0].data_type = PJSIP_CRED_DATA_PLAIN_PASSWD;
    cfg.cred_info[0].data = pj_str((char*)sipPassword);
    cfg.reg_retry_interval = 30;

    //pj_log_set_level(6);

    status = pjsua_acc_add(&cfg, PJ_TRUE, &acc_id);
    if (status != PJ_SUCCESS) error_exit("Error adding account", status);
}

return 0;

}

这些是激活后 pjsip 打印的第一行

15:51:51.442 os_core_unix.c !pjlib 2.4.5 for POSIX initialized
15:51:51.444 sip_endpoint.c  .Creating endpoint instance...
15:51:51.444          pjlib  .select() I/O Queue created (0x16295940)
15:51:51.444 sip_endpoint.c  .Module "mod-msg-print" registered
15:51:51.445 sip_transport.  .Transport manager created.
15:51:51.445   pjsua_core.c  .PJSUA state changed: NULL --> CREATED
15:51:51.447 sip_endpoint.c  .Module "mod-pjsua-log" registered
15:51:51.447 sip_endpoint.c  .Module "mod-tsx-layer" registered
15:51:51.447 sip_endpoint.c  .Module "mod-stateful-util" registered
15:51:51.447 sip_endpoint.c  .Module "mod-ua" registered
15:51:51.448 sip_endpoint.c  .Module "mod-100rel" registered
15:51:51.448 sip_endpoint.c  .Module "mod-pjsua" registered
15:51:51.448 sip_endpoint.c  .Module "mod-invite" registered
15:51:51.490 coreaudio_dev.  .. dev_id 0: iPhone IO device  (in=1, out=1) 8000Hz
15:51:51.508 coreaudio_dev.  ..core audio initialized
15:51:51.509          pjlib  ..select() I/O Queue created (0x16a63e14)
15:51:51.547 sip_endpoint.c  .Module "mod-evsub" registered
15:51:51.547 sip_endpoint.c  .Module "mod-presence" registered
15:51:51.547 sip_endpoint.c  .Module "mod-mwi" registered
15:51:51.548 sip_endpoint.c  .Module "mod-refer" registered
15:51:51.548 sip_endpoint.c  .Module "mod-pjsua-pres" registered
15:51:51.548 sip_endpoint.c  .Module "mod-pjsua-im" registered
15:51:51.548 sip_endpoint.c  .Module "mod-pjsua-options" registered
15:51:51.549   pjsua_core.c  .1 SIP worker threads created
15:51:51.549   pjsua_core.c  .pjsua version 2.4.5 for iPhone OS-9.2/arm-iPhone4,1/iOS-SDK-9.2 initialized
15:51:51.549   pjsua_core.c  .PJSUA state changed: CREATED --> INIT
15:51:51.554   pjsua_core.c  SIP UDP socket reachable at    192.168.100.174:5060
15:51:51.556  udp0x16ab8400  SIP UDP transport started, published address is 192.168.100.174:5060
15:51:51.559     tcptp:5060  SIP TCP listener ready for incoming connections at 192.168.100.174:5060
15:51:51.559   pjsua_core.c  PJSUA state changed: INIT --> STARTING
15:51:51.559 sip_endpoint.c  .Module "mod-unsolicited-mwi" registered
15:51:51.559   pjsua_core.c  .PJSUA state changed: STARTING --> RUNNING
15:51:51.560    pjsua_acc.c  Adding account: id=sip:2011@37.187.161.173
15:51:51.561    pjsua_acc.c  .Account sip:2011@37.187.161.173 added with id 0
15:51:51.561    pjsua_acc.c  .Acc 0: setting registration..
15:51:51.563 tcpc0x1629d414  ..TCP client transport created
15:51:51.564 tcpc0x1629d414  ..TCP transport 192.168.100.174:49474 is connecting to 37.187.161.173:5060...
15:51:51.564    pjsua_acc.c  ..Contact for acc 0 updated for SIP outbound: <sip:2011@192.168.100.174:49474;transport=TCP;ob>;reg-id=1;+sip.instance="<urn:uuid:00000000-0000-0000-0000-0000d3a3575f>"
15:51:51.566   pjsua_core.c  ...TX 629 bytes Request msg REGISTER/cseq=17104 (tdta0x16abce00) to TCP 37.187.161.173:5060:
REGISTER sip:37.187.161.173;transport=tcp SIP/2.0

我确定我正在使用 TCP 作为套接字，我刚刚尝试删除 udp 套接字，但没有任何改变。环顾四周，我发现有人遇到了同样的问题，但几分钟后，我的问题在半分钟或更长时间后出现。

我什至尝试设置 pjsip 的 keepalive 间隔，正如您从这些行中看到的那样：

pjsip_cfg_t *mysipcfg = pjsip_cfg();
mysipcfg->tcp.keep_alive_interval = 20;

我将它设置为 20 秒，但没有任何改变。 在后台模式中添加了语音和音频功能。

我通过网络监视器看到，当应用程序处于前台时，与 voip 服务器的连接处于活动状态。当应用程序进入后台时，此连接会在 3-4 秒后消失。无论如何，我仍然能够在 30-40 秒内接听来电。

知道我做错了什么吗？

Answer 1

一般来说，PJSIP 将仅通过 UDP 传输连接。如果你也想在后台来电，你只需要通过 TCP 传输连接，TCP 传输只支持实时数据传输。它遵循请求确认机制，因此如果应用程序处于后台状态，调用将访问应用程序并显示本地通知或您为后台实现的其他内容。在UDP中它不会检查数据包是否被传递，在TCP中它会检查。所以，要在后台接听来电，请强制将连接完全设置为仅 TCP，不要启用 UDP。

Answer 2

刚刚自己找到了解决方案。问题是 pjsua 配置的 reg_timeout。我使用了从服务器传递的值（60 秒）。当应用程序处于前台时，此值是正确的。当我的应用在后台运行时，注册不会在 60 秒后过期，并且 pjsip 无法更新它，因为 iOS 应用从后台唤醒的最短保活时间为 600 秒。

解决方案是在应用切换到后台时更改注册超时。

你需要这样的函数：

void change timeout() {
    pjsua_acc_config = cfg;
    pjsua_acc_get_config(acc_id, pool, cfg);
    cgf.reg_timeout = 600;
    pjsua_acc_modify_config(acc_id, cfg)
}

只需在应用切换到后台时调用此函数并将 reg_timeout 更改为 600。然后重新注册。当应用程序返回到前台时，您会使用原始超时执行相同的操作。

注意，这应该随着 Xcode 8 和 iOS 10 强制 VOIP 推送和禁用 VOIP 后台模式而改变。截至 2016 年 1 月，如果应用程序处于离线状态，您将需要从服务器请求 VOIP 推送。

Answer 3

对于 VOIP 后台，请在 AppDelegate.m 中使用此功能

- (void)applicationDidEnterBackground:(UIApplication *)application
{
   [self performSelectorOnMainThread:@selector(keepAlive) withObject:nil waitUntilDone:YES];

    [[UIApplication sharedApplication] setKeepAliveTimeout:600 handler: ^{
        [self performSelectorOnMainThread:@selector(keepAlive) withObject:nil waitUntilDone:YES];

    }];

}

static pj_thread_desc   a_thread_desc;
static pj_thread_t     *a_thread;

- (void)keepAlive {
   int i;

  NSLog(@"Keep alive starts");
  if (!pj_thread_is_registered())
  {
     pj_thread_register("ipjsua", a_thread_desc, &a_thread);
  }

/* Since iOS requires that the minimum keep alive interval is 600s,
 * application needs to make sure that the account's registration
 * timeout is long enough.
 */
for (i = 0; i < (int)pjsua_acc_get_count(); ++i) {
    if (pjsua_acc_is_valid(i)) {
        pjsua_acc_set_registration(i, PJ_TRUE);
    }
}


}

它应该可以工作..

Answer 4

当您的应用在后台运行时，注册会在 60 秒后过期，并且 pjsip 无法续订它，因为 iOS 应用从后台唤醒的最短保活时间为 600 秒。