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/* sntp.c - sntp client and server
*
* Copyright 2019 Rob Landley <rob@landley.net>
*
* See https://www.ietf.org/rfc/rfc4330.txt
USE_SNTP(NEWTOY(sntp, "<1", TOYFLAG_USR|TOYFLAG_BIN))
config SNTP
bool "sntp"
default n
help
usage: sntp SERVER...
Simple Network Time Protocol client, set system clock from a server.
*/
#define FOR_sntp
#include "toys.h"
GLOBALS(
int unused;
)
union socksaddr {
struct sockaddr_in in;
struct sockaddr_in6 in6;
};
// timeout in milliseconds
int xrecvwait(int fd, char *buf, int len, union socksaddr *sa, int timeout)
{
socklen_t sl = sizeof(*sa);
if (timeout >= 0) {
struct pollfd pfd;
pfd.fd = fd;
pfd.events = POLLIN;
if (!xpoll(&pfd, 1, timeout)) return 0;
}
len = recvfrom(fd, buf, len, 0, (void *)sa, &sl);
if (len<0) perror_exit("recvfrom");
return len;
}
void sntp_main(void)
{
struct addrinfo *ai;
union socksaddr sa;
int fd, len;
ai = xgetaddrinfo(*toys.optargs, 0, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, 0);
// When root, bind to local server address
if (!getuid())
fd = xbind(xgetaddrinfo("", "123", AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, 0));
else fd = xsocket(ai->ai_family, SOCK_DGRAM, IPPROTO_UDP);
xsendto(fd, toybuf, 48, ai->ai_addr);
len = xrecvwait(fd, toybuf, sizeof(toybuf), &sa, 5000);
printf("%d\n", len);
if (len>0) write(1, toybuf, len);
}
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