sntp client and server

hai guys iam planning to develop sntp client and server ,here i am keeping i devloped code for sntp client and server with a loop back address
[Code]
/**************************** sntpclient.c ************************************/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
/* includes for socket delarations */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SRV_IP_ADRS "127.0.0.1"
#define SRV_UDP_PORT 123


void errExit(char *str)
{
puts(str);
exit(0);
}
typedef struct
{
unsigned char mode : 3;
unsigned char vn : 3;
unsigned char li : 2;
unsigned char stratum;
int poll;
int precision;
unsigned long root_delay;
unsigned long root_dispersion;
unsigned long reference_identifier;
unsigned long reference_timestamp_secs;
unsigned long originate_timestamp_secs;
unsigned long receive_timestamp_secs;
unsigned long transmit_timestamp_secs;

}sntp_packet;

int main()
{
int sockFd;
struct sockaddr_in srvAdr,cliAdr;
sntp_packet sntp_msg_header;
sntp_packet rxmsg;
int n;

if( (sockFd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
errExit("Can't open datagram socket\n");

memset(&srvAdr,0,sizeof(srvAdr));
srvAdr.sin_family = AF_INET;
srvAdr.sin_addr.s_addr = inet_addr(SRV_IP_ADRS);
srvAdr.sin_port = htons(SRV_UDP_PORT);

sntp_msg_header.mode=3;
sntp_msg_header.vn =4;
sntp_msg_header.li =0;
sntp_msg_header.stratum=0;
sntp_msg_header.poll=0;
sntp_msg_header.precision=0;
sntp_msg_header.root_delay=0;
sntp_msg_header.root_dispersion=0;
sntp_msg_header.reference_identifier=0;
sntp_msg_header.reference_timestamp_secs=0;
sntp_msg_header.originate_timestamp_secs=0;
sntp_msg_header.receive_timestamp_secs=0;
sntp_msg_header.transmit_timestamp_secs=time(NULL);

n = sizeof(sntp_packet);
if(sendto(sockFd,&sntp_msg_header,n,0,(struct sockaddr*)&srvAdr,sizeof(srvAdr)) != n)
errExit("sendto error\n");

n = recv(sockFd,(sntp_packet*)&rxmsg,sizeof(rxmsg), 0);
if(n < 0)
errExit("recv error\n");

printf("Received following message:\n%u \n%u \n%u \n%u \n%d \n%d \n%ld \n%ld \n%ld \n%ld \n%ld \n%ld \n%ld",rxmsg.mode,rxmsg.vn,rxmsg.li,rxmsg.stratum,rxmsg.poll,rxmsg.precision, rxmsg.root_delay,rxmsg.root_dispersion,rxmsg.reference_identifier,rxmsg.reference_timestamp_secs,rxmsg.originate_timestamp_secs,rxmsg.receive_timestamp_secs,rxmsg.transmit_timestamp_secs);
}
[/Code]
and server is
[Code]

/**************************** sntp srver.c ************************************/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
/* standard include for socket definitions */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>

#define SRV_UDP_PORT 8000


void errExit(char *str)
{
char errorBuff[100];
puts(str);
perror(errorBuff);
exit(0);
}
typedef struct
{
unsigned char mode : 3;
unsigned char vn : 3;
unsigned char li : 2;
unsigned char stratum;
int poll;
int precision;
unsigned long root_delay;
unsigned long root_dispersion;
unsigned long reference_identifier;
unsigned long reference_timestamp_secs;
unsigned long originate_timestamp_secs;
unsigned long receive_timestamp_secs;
unsigned long transmit_timestamp_secs;
}sntp_packet;

int main()
{
int sockFd;
struct sockaddr_in srvAdr, cliAdr;
int cliLen,n;
sntp_packet srv_header;
sntp_packet srv;

if( (sockFd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
errExit("Can't open datagram socket\n");

memset(&srvAdr,0,sizeof(srvAdr));
srvAdr.sin_family = AF_INET;
srvAdr.sin_addr.s_addr = htonl(INADDR_ANY);
srvAdr.sin_port = htons(SRV_UDP_PORT);

if(bind(sockFd,(struct sockaddr*)&srvAdr, sizeof(srvAdr)) < 0)
errExit("Can't bind local address\n");

printf("Server waiting for messages\n");
while(1)
{
cliLen = sizeof(cliAdr);
n = recvfrom(sockFd, (sntp_packet *)&srv, sizeof(sntp_packet), 0, (struct sockaddr *)&cliAdr, &cliLen);
srv_header.mode=4;
srv_header.li =0;
srv_header.vn =srv.vn;
srv_header.stratum=1;
srv_header.poll=srv.poll;
srv_header.precision=0;// -log2 server significant bits (srv->precision;)
srv_header.root_delay=0;
srv_header.root_dispersion=0;
srv_header.reference_identifier=0;//ntp.pool.org();
srv_header.reference_timestamp_secs=0;//ntp.pool.org();
srv_header.originate_timestamp_secs=srv.originate_timestamp_secs;
srv_header.receive_timestamp_secs=time(NULL);//"time of day";
srv_header.transmit_timestamp_secs=time(NULL);//"time of day";

if(n < 0)
errExit("recvfrom error\n");

if(sendto(sockFd,(sntp_packet*)&srv_header,n,0,(struct sockaddr *)&cliAdr,cliLen) != n)
errExit("sendto error\n");

printf("Received messages:\n%u \n%u \n%u \n%u \n%d \n%d \n%ld \n%ld \n%ld \n%ld \n%ld \n%ld \n%ld\n",srv.mode,srv.vn,srv.li,srv.stratum,srv.poll,srv.precision, srv.root_delay,srv.root_dispersion,srv.reference_identifier,srv.reference_timestamp_secs,srv.originate_timestamp_secs,srv.receive_timestamp_secs,srv.transmit_timestamp_secs);

printf("Above messages recieved from client %s",
inet_ntoa(cliAdr.sin_addr));
}
}

[/Code]
here whats my doubt is what data client can put in originate time stamp and transmitt time stamp in order to send to to the sntp server ?
how to calculate precision, rootdelay, root_idspersion with respect to server?
how sntp server will contact reference identifier and which external source will it synchronized and how?
if sntp client put poll interval is 4 , how will client can poll the server 4 times?