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libmsntp.h
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libmsntp.h
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/**
* libmsntp
* http://snarfed.org/libmsntp
*
* Copyright 2005, Ryan Barrett <[email protected]>
*
* libmsntp is a shared library that provides SNTP client and server
* functionality. It allows you to embed an SNTP client and/or server in your
* own programs. It's implemented on top of msntp, a command-line SNTP tool
* from Cambridge.
*
* Errors can be handled programmatically by examing each function's return
* value - if positive, it's an errno constant; if negative, it's one of the
* EMSNTP_ constants defined immediately below. The msntp_strerror function
* returns a human-readable string describing the last error encountered.
*
* To use libmsntp in your own programs, include libmsntp.h and link with
* libmsntp.a. For more information on building libmsntp, see the README file.
*/
#ifndef _LIBMSNTP_H
#define _LIBMSNTP_H
#include <sys/time.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* Error constants, used as return values from the libmsntp functions.
*/
#define EMSNTP_UNKNOWN -10
#define EMSNTP_INTERNAL -11
#define EMSNTP_IP_ADDRESS -12
#define EMSNTP_AF_INET -13
#define EMSNTP_TOO_FEW_RESPONSES -14
#define EMSNTP_BAD_RESPONSES -15
#define EMSNTP_NO_GOOD_RESPONSE -16
#define EMSNTP_NTP_INCONSISTENCY -17
#define EMSNTP_NTP_INSANITY -18
/**
* Connects to an SNTP server and synchronizes the local clock to the server's
* clock.
*
* The port should be in host byte order.
*/
int msntp_set_clock(char *hostname, int port);
/**
* Connects to an SNTP server and returns the difference between its clock and
* the local clock, as a struct timeval. If positive, the server clock is ahead
* of the local clock; if negative, the server clock is behind the local clock.
*
* The port should be in host byte order.
*/
int msntp_get_offset(char *hostname, int port, struct timeval *offset);
/**
* Connects to an SNTP server and returns its current time. Since the value of
* this is largely based on how quickly you can use it, it's recommended that
* you use msntp_set_clock or msntp_get_offset instead.
*
* The port should be in host byte order.
*/
int msntp_get_time(char *hostname, int port, struct timeval *server_time);
/**
* Starts the SNTP server. The port should be in host byte order.
*/
int msntp_start_server(int port);
/**
* Handles incoming conections from SNTP clients. This call is non-blocking; it
* will either accept and handle a single SNTP request, or time out and return.
* Should only be called after msntp_start_server.
*/
int msntp_serve();
/**
* Stops the SNTP server. Should only be called after msntp_start_server.
*/
int msntp_stop_server();
/**
* Returns a a detailed, human-readable string describing the last error
* encountered.
*/
const char *msntp_strerror();
#ifdef __cplusplus
}
#endif
#endif //_LIBMSNTP_H