long
u_ntp_ack(int sockfd, struct timeval *tv)
{
int len;
uint32_t packet[12];
len = recv(sockfd, packet, sizeof(packet), 0);
close(sockfd);
if (len == sizeof(packet))
{
rfc1305(packet, tv);
return 1;
}
return 0;
}
int main(int argc, char *argv[])
{
int usd;
struct sockaddr_in sa;
struct hostent *he;
struct timeval tv;
fd_set fds;
int i;
char *srv;
char buf[256];
// printf("mini ntpclient\n");
if (argc <= 1) {
printf("Usage: %s <server> [server [...]]\n", argv[0]);
return 1;
}
for (i = 1; i < argc; ++i) {
// ntp.c passes servers as one block of string, so we need to break it down
strcpy(buf, argv[i]);
srv = strtok(buf, " ");
while (srv) {
if ((usd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
printf("socket error");
return 1;
}
if ((he = gethostbyname(srv)) != NULL) {
memset(&sa, 0, sizeof(sa));
memcpy(&sa.sin_addr, he->h_addr_list[0], sizeof(sa.sin_addr));
sa.sin_port = htons(NTP_PORT);
sa.sin_family = AF_INET;
//printf("trying %s [%s]\n", argv[i], inet_ntoa(sa.sin_addr));
if (connect(usd, (struct sockaddr*)&sa, sizeof(sa)) != -1) {
send_packet(usd);
tv.tv_sec = 3;
tv.tv_usec = 0;
FD_ZERO(&fds);
FD_SET(usd, &fds);
if (select(usd + 1, &fds, NULL, NULL, &tv) == 1) {
int len;
uint32_t packet[12];
len = recv(usd, packet, sizeof(packet), 0);
if (len == sizeof(packet)) {
rfc1305(packet);
close(usd);
printf("Time updated.\n");
return 0;
}
}
}
else {
perror("connect");
}
}
else {
perror("gethostbyname");
}
close(usd);
srv = strtok(NULL, " ");
}
}
return 1;
}
