Gb28181 protocol -- timing

1、 brief introduction

according to 《GB/T 28181 —2016》7.10、9.10 The requirements of ,GB28181 The equipment network timing function is described as follows ：
In networked systems IP Network server equipment should support NTP( see IETF RFC2030) Network unified timing service based on Protocol . Network timing equipment is divided into clock source and client , Support customers / The working mode of the server ; The clock source shall support TCP/IP、UDP And NTP agreement , It can convert the input or self generated time signal to standard NTP Packet format output . In networked systems IP The network access equipment shall support SIP Unified timing of signaling , The access device shall accept the data from SIP The server passes the message header Date Time service carried by domain .

2、 The basic flow

Intranet device support is based on SIP Method or NTP Network timing function of mode , The standard time is Beijing time . The process is as follows ：

If the registration is successful , The last part of the registration process SIP Reply message 200 OK Medium Date The header field carries the time information . The format is XML A standard format :Date: yyyy-MM-dd’T’HH: mm:ss.SSS.
if SIP The agent corrects the time through registration , Its registration expiration time should be set to less than SIP Agency and SIP The server appears 1 s The elapsed time of the error . for example :SIP Agency and SIP After the server timing ,SIP The agent runs 10 h Post equipment time and SIP The server time difference is greater than 1 s, The registration expiration time should be set to 10 h(36 000s) , In order to make sure SIP Agency and SIP The time error between servers is less than 1 s.

3、 be based on SIP Timing of

sip Signaling processing ：

int SipReg(GB28181Param_t *pGB28181Param, int isReg)
{
    
	int ret = 0;
	int len = 0;
	char *msg;
	int expires = 0 ;
	int regState = 0;
	int unAuthorized = 0;
	eXosip_event_t *je = NULL;
	osip_header_t *dest = NULL;
	osip_message_t *reg = NULL;
	long interval = GetSysSec();


	
	if (!pGB28181Param)
	{
    
		return SIP_FAILED;
	}

	if (isReg)
	{
    
		expires = strtoul(pGB28181Param->userParam.sipExpires, 0, 0);
	}

	while(GetSysSec() -interval <= MAX_SIP_REG_TIMEOUT_SEC)
	{
    
		//  Advanced bank does not have certification registration 
		if (0 == unAuthorized)
		{
    
			ret = SipRegisterUnauthorized(pGB28181Param, expires);
			if (ret < 0)
			{
    
				if(je)
				{
    
					eXosip_event_free(je);
				}
				return SIP_FAILED;
			}
			else 
			{
    
				unAuthorized = 1;
			}
		}

		je = eXosip_event_wait(0, 100);  		/*  Waiting for new news  */
		if(NULL == je)
		{
    
			/*  The following statement will result in eXosip_register_send_register Failure  */
			eXosip_automatic_action();
			usleep(100*1000);
			continue;
		}

		/*  Return registration failure  */
		if(EXOSIP_REGISTRATION_FAILURE == je->type)
		{
    
			/*  Unauthenticated registration failed , Then use authentication to register  */
			if((je->response!=NULL) && (401==je->response->status_code))
			{
    
				ret = SipRegisterAuthorized(pGB28181Param, je->rid, expires);
				eXosip_event_free(je);
				if(ret != OSIP_SUCCESS)
				{
    
					return SIP_FAILED;
				}
			}
			else 
			{
    
				eXosip_event_free(je);
				unAuthorized = 0;			/*  Registration failed ,  Go through the registration process again  */
				if (isReg)
				{
    
					return SIP_REREG_AFTER_60S;
				}
				return SIP_FAILED;
			}
		}
		else if (EXOSIP_REGISTRATION_SUCCESS == je->type)
		{
    
			regState = 1;
			/*  The registration returned by the server is successful  */
			g_SipState.registerID = je->rid;	
			if (MSG_IS_REGISTER(je->request) && je->response)
			{
    
				if (OSIP_SUCCESS == osip_message_to_str(je->response, &msg, &len))
				{
    
					if (osip_message_get_date(je->response, 0, &dest) > 0)
					{
    
						SipSetSystemTime(dest->hvalue);
					}
				}
			}
			
			eXosip_execute();
			eXosip_automatic_action();
			eXosip_event_free(je);
			break;
		}
		else
		{
    
			eXosip_event_free(je);
		}
	}

	if( (GetSysSec() -interval > MAX_SIP_REG_TIMEOUT_SEC) && (regState == 0))
	{
    
		return SIP_FAILED;
	}

	pthread_mutex_lock(&g_SipState.mutex);
	//  to update sip Registration status of 
	if (isReg)
	{
    
		g_SipState.sipRegStatus = 1;
		g_SipState.keepliveAckTime = GetSysSec();
	}
	else 
	{
    
		g_SipState.sipRegStatus = 0;
	}
	pthread_mutex_unlock(&g_SipState.mutex);
	
	return SIP_SUCCESS;
}

Set the system time interface ：

static int SipSetSystemTime(char *timeStr)
{
    
	char *beginStr = timeStr;
	char *endStr = NULL;
	char tempStr[10] = {
    0, };
	struct tm st_time = {
    0, };
	struct timeval tv = {
    0, };
	uint32_t stime = 0;

	
	if (!timeStr)
	{
    
		return SIP_FAILED;
	}

	if ((endStr = strstr(beginStr, "-")))
	{
    
		memset(tempStr, 0, sizeof(tempStr));
		strncpy(tempStr, beginStr, endStr-beginStr);
		beginStr = endStr + 1;
		stime = strtoul(tempStr, NULL, sizeof(tempStr));
		st_time.tm_year = stime - 1900;
	}

	if ((endStr = strstr(beginStr, "-")))
	{
    
		memset(tempStr, 0, sizeof(tempStr));
		strncpy(tempStr, beginStr, endStr-beginStr);
		beginStr = endStr + 1;
		stime = strtoul(tempStr, NULL, sizeof(tempStr));
		st_time.tm_mon = stime - 1;
	}

	if ((endStr = strstr(beginStr, "T")))
	{
    
		memset(tempStr, 0, sizeof(tempStr));
		strncpy(tempStr, beginStr, endStr-beginStr);
		beginStr = endStr + 1;
		stime = strtoul(tempStr, NULL, sizeof(tempStr));
		st_time.tm_mday = stime;
	}

	if ((endStr = strstr(beginStr, ":")))
	{
    
		memset(tempStr, 0, sizeof(tempStr));
		strncpy(tempStr, beginStr, endStr-beginStr);
		beginStr = endStr + 1;
		stime = strtoul(tempStr, NULL, sizeof(tempStr));
		st_time.tm_hour = stime;
	}

	if ((endStr = strstr(beginStr, ":")))
	{
    
		memset(tempStr, 0, sizeof(tempStr));
		strncpy(tempStr, beginStr, endStr-beginStr);
		beginStr = endStr + 1;
		stime = strtoul(tempStr, NULL, sizeof(tempStr));
		st_time.tm_min = stime;
	}

	if ((endStr = strstr(beginStr, ".")))
	{
    
		memset(tempStr, 0, sizeof(tempStr));
		strncpy(tempStr, beginStr, endStr-beginStr);
		beginStr = endStr + 1;
		stime = strtoul(tempStr, NULL, sizeof(tempStr));
		st_time.tm_sec = stime;
	}

	//  Set system time 
	if ((tv.tv_sec = mktime(&st_time)) < 0)
	{
    
		GB_PrintError("mktime failed\n");
		return SIP_FAILED;
	}

	settimeofday(&tv, NULL);

	//  Set up RTC Time 
	struct tm *stTime = gmtime(&tv);
	if (SetRtcTime(stTime) < 0)
	{
    
		return SIP_FAILED;		
	}

	return SIP_SUCCESS;
}

Reference material ：
《GBT 28181-2016 Public security video monitoring network system information transmission 、 In exchange for 、 Control technical requirements 》
Recommended reading ：GB28181 agreement – Device registration and logout