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/*
* Utility code to return the number of NTP peers of a system.
*
* This code is xntpdc's monlist command butchered and packaged in a single
* source file.
*
* Modified fom xntpd source by Larry Schwimmer
* Copyright 1992-1997 University of Delaware
* Copyright 1997, 1998, 2008, 2012
* The Board of Trustees of the Leland Stanford Junior University
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose with or without fee is hereby granted,
* provided that the above copyright notice appears in all copies and that
* both the copyright notice and this permission notice appear in supporting
* documentation, and that the name University of Delaware not be used in
* advertising or publicity pertaining to distribution of the software without
* specific, written prior permission. The University of Delaware makes no
* representations about the suitability this software for any purpose. It is
* provided "as is" without express or implied warranty.
*/
#include <config.h>
#include <portable/socket.h>
#include <portable/system.h>
#include <ctype.h>
#ifdef HAVE_SYS_SELECT_H
# include <sys/select.h>
#endif
#include <sys/time.h>
#include <modules/monlist.h>
/* The maximum packets of rely to read from the server. */
#define MAXPACKETS 100
/*
* Format and send a request packet.
*/
static int
sendrequest(int sd, int implcode, int reqcode)
{
struct req_pkt qpkt;
memset(&qpkt, 0, sizeof qpkt);
qpkt.rm_vn_mode = RM_VN_MODE(0, 0);
qpkt.implementation = (uint8_t) implcode;
qpkt.request = (uint8_t) reqcode;
qpkt.err_nitems = ERR_NITEMS(0, 0);
qpkt.mbz_itemsize = MBZ_ITEMSIZE(0);
qpkt.auth_seq = AUTH_SEQ(0, 0);
if (send(sd, &qpkt, REQ_LEN_NOMAC, 0) == -1)
return -1;
return 0;
}
/*
* Get number of entries in the first packet.
*/
static int
getresponse(int sd, int implcode, int reqcode, int *ritems, int timeout)
{
struct resp_pkt rpkt;
struct timeval tv = { 0, 0 };
int seq;
fd_set fds;
int n;
int seenpacket[MAXPACKETS];
int lastseq = 999;
int numrecv = 0;
tv.tv_sec = timeout;
*ritems = 0;
memset(seenpacket, 0, sizeof(seenpacket));
/* Receive reply packet. */
while (1) {
FD_ZERO(&fds);
FD_SET(sd, &fds);
n = select(sd + 1, &fds, NULL, NULL, &tv);
if (n < 1)
return -1;
n = recv(sd, (char *)&rpkt, sizeof(rpkt), 0);
if (n == -1)
return -1;
/* Check for format errors. */
if ((n < RESP_HEADER_SIZE)
|| (INFO_VERSION(rpkt.rm_vn_mode) != NTP_VERSION)
|| (INFO_MODE(rpkt.rm_vn_mode) != MODE_PRIVATE)
|| (INFO_IS_AUTH(rpkt.auth_seq))
|| (!ISRESPONSE(rpkt.rm_vn_mode))
|| (INFO_MBZ(rpkt.mbz_itemsize) != 0))
continue;
/* Check implementation/request. Could be old data getting to us. */
if (rpkt.implementation != implcode || rpkt.request != reqcode)
continue;
/* Check the error code. If non-zero, return it. */
if (INFO_ERR(rpkt.err_nitems) != INFO_OKAY)
return INFO_ERR(rpkt.err_nitems);
/* If it isn't the first packet, we don't care. */
seq = INFO_SEQ(rpkt.auth_seq);
if (seq >= MAXPACKETS)
continue;
if (seenpacket[seq])
continue;
seenpacket[seq]++;
/* Collect items and size. Make sure they make sense. */
*ritems += INFO_NITEMS(rpkt.err_nitems);
/* Check if end of sequence packet. */
if (!ISMORE(rpkt.rm_vn_mode)) {
if (lastseq != 999)
continue;
lastseq = seq;
}
/* Check if done. */
numrecv++;
if (numrecv <= lastseq)
continue;
break;
}
return 0;
}
/*
* Return number of NTP peers for a machine.
*/
int
monlist(int sd, int timeout)
{
int res, peers;
/* Send monlist request. */
res = sendrequest(sd, IMPL_XNTPD, REQ_MON_GETLIST);
if (res != 0)
return -1;
/* Get the monlist response. */
res = getresponse(sd, IMPL_XNTPD, REQ_MON_GETLIST, &peers, timeout);
if (res != 0)
return -1;
return peers;
}
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