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/* $OpenBSD: client.c,v 1.65 2005/08/10 13:48:36 dtucker Exp $ */
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/*
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* Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
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* Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
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* IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
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* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/param.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include "ntpd.h"
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int client_update(struct ntp_peer *);
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void set_deadline(struct ntp_peer *, time_t);
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void
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set_next(struct ntp_peer *p, time_t t)
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{
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p->next = time(NULL) + t;
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p->deadline = 0;
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}
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void
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set_deadline(struct ntp_peer *p, time_t t)
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{
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p->deadline = time(NULL) + t;
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p->next = 0;
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}
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int
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client_peer_init(struct ntp_peer *p)
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{
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if ((p->query = calloc(1, sizeof(struct ntp_query))) == NULL)
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fatal("client_peer_init calloc");
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p->query->fd = -1;
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p->query->msg.status = MODE_CLIENT | (NTP_VERSION << 3);
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p->state = STATE_NONE;
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p->shift = 0;
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p->trustlevel = TRUSTLEVEL_PATHETIC;
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p->lasterror = 0;
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return (client_addr_init(p));
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}
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int
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client_addr_init(struct ntp_peer *p)
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{
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struct sockaddr_in *sa_in;
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struct sockaddr_in6 *sa_in6;
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struct ntp_addr *h;
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for (h = p->addr; h != NULL; h = h->next) {
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switch (h->ss.ss_family) {
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case AF_INET:
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sa_in = (struct sockaddr_in *)&h->ss;
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if (ntohs(sa_in->sin_port) == 0)
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sa_in->sin_port = htons(123);
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p->state = STATE_DNS_DONE;
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break;
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case AF_INET6:
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sa_in6 = (struct sockaddr_in6 *)&h->ss;
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if (ntohs(sa_in6->sin6_port) == 0)
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sa_in6->sin6_port = htons(123);
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p->state = STATE_DNS_DONE;
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break;
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default:
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fatal("king bula sez: wrong AF in client_addr_init");
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/* not reached */
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}
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}
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p->query->fd = -1;
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set_next(p, 0);
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return (0);
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}
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int
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client_nextaddr(struct ntp_peer *p)
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{
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close(p->query->fd);
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p->query->fd = -1;
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if (p->addr_head.a == NULL) {
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priv_host_dns(p->addr_head.name, p->id);
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p->state = STATE_DNS_INPROGRESS;
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return (-1);
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}
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if ((p->addr = p->addr->next) == NULL)
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p->addr = p->addr_head.a;
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p->shift = 0;
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p->trustlevel = TRUSTLEVEL_PATHETIC;
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return (0);
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}
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int
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client_query(struct ntp_peer *p)
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{
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int tos = IPTOS_LOWDELAY;
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if (p->addr == NULL && client_nextaddr(p) == -1) {
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set_next(p, error_interval());
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return (0);
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}
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if (p->state < STATE_DNS_DONE || p->addr == NULL)
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return (-1);
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if (p->query->fd == -1) {
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struct sockaddr *sa = (struct sockaddr *)&p->addr->ss;
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if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM,
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0)) == -1)
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fatal("client_query socket");
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if (connect(p->query->fd, sa, SA_LEN(sa)) == -1) {
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if (errno == ECONNREFUSED || errno == ENETUNREACH ||
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errno == EHOSTUNREACH) {
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client_nextaddr(p);
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set_next(p, error_interval());
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return (-1);
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} else
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fatal("client_query connect");
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}
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if (p->addr->ss.ss_family == AF_INET && setsockopt(p->query->fd,
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IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1)
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log_warn("setsockopt IPTOS_LOWDELAY");
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}
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/*
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* Send out a random 64-bit number as our transmit time. The NTP
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* server will copy said number into the originate field on the
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* response that it sends us. This is totally legal per the SNTP spec.
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*
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* The impact of this is two fold: we no longer send out the current
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* system time for the world to see (which may aid an attacker), and
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* it gives us a (not very secure) way of knowing that we're not
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* getting spoofed by an attacker that can't capture our traffic
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* but can spoof packets from the NTP server we're communicating with.
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*
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* Save the real transmit timestamp locally.
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*/
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p->query->msg.xmttime.int_partl = arc4random();
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p->query->msg.xmttime.fractionl = arc4random();
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p->query->xmttime = gettime();
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if (ntp_sendmsg(p->query->fd, NULL, &p->query->msg,
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NTP_MSGSIZE_NOAUTH, 0) == -1) {
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set_next(p, INTERVAL_QUERY_PATHETIC);
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return (-1);
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}
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p->state = STATE_QUERY_SENT;
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set_deadline(p, QUERYTIME_MAX);
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return (0);
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}
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int
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client_dispatch(struct ntp_peer *p, u_int8_t settime)
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{
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char buf[NTP_MSGSIZE];
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ssize_t size;
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struct ntp_msg msg;
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double T1, T2, T3, T4;
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time_t interval;
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if ((size = recvfrom(p->query->fd, &buf, sizeof(buf), 0,
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NULL, NULL)) == -1) {
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if (errno == EHOSTUNREACH || errno == EHOSTDOWN ||
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errno == ENETUNREACH || errno == ENETDOWN ||
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errno == ECONNREFUSED || errno == EADDRNOTAVAIL) {
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client_log_error(p, "recvfrom", errno);
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set_next(p, error_interval());
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return (0);
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} else
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fatal("recvfrom");
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}
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T4 = gettime();
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ntp_getmsg(buf, size, &msg);
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if (msg.orgtime.int_partl != p->query->msg.xmttime.int_partl ||
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msg.orgtime.fractionl != p->query->msg.xmttime.fractionl)
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return (0);
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if ((msg.status & LI_ALARM) == LI_ALARM || msg.stratum == 0 ||
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msg.stratum > NTP_MAXSTRATUM) {
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interval = error_interval();
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set_next(p, interval);
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log_info("reply from %s: not synced, next query %ds",
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log_sockaddr((struct sockaddr *)&p->addr->ss), interval);
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return (0);
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}
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/*
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* From RFC 2030 (with a correction to the delay math):
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*
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* Timestamp Name ID When Generated
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* ------------------------------------------------------------
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* Originate Timestamp T1 time request sent by client
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* Receive Timestamp T2 time request received by server
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* Transmit Timestamp T3 time reply sent by server
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* Destination Timestamp T4 time reply received by client
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*
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* The roundtrip delay d and local clock offset t are defined as
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*
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* d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2.
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*/
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T1 = p->query->xmttime;
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T2 = lfp_to_d(msg.rectime);
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T3 = lfp_to_d(msg.xmttime);
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p->reply[p->shift].offset = ((T2 - T1) + (T3 - T4)) / 2;
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p->reply[p->shift].delay = (T4 - T1) - (T3 - T2);
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if (p->reply[p->shift].delay < 0) {
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interval = error_interval();
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set_next(p, interval);
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log_info("reply from %s: negative delay %f",
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log_sockaddr((struct sockaddr *)&p->addr->ss),
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p->reply[p->shift].delay);
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return (0);
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}
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p->reply[p->shift].error = (T2 - T1) - (T3 - T4);
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p->reply[p->shift].rcvd = time(NULL);
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p->reply[p->shift].good = 1;
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p->reply[p->shift].status.leap = (msg.status & LIMASK);
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p->reply[p->shift].status.precision = msg.precision;
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p->reply[p->shift].status.rootdelay = sfp_to_d(msg.rootdelay);
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p->reply[p->shift].status.rootdispersion = sfp_to_d(msg.dispersion);
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p->reply[p->shift].status.refid = ntohl(msg.refid);
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p->reply[p->shift].status.refid4 = msg.xmttime.fractionl;
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p->reply[p->shift].status.reftime = lfp_to_d(msg.reftime);
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p->reply[p->shift].status.poll = msg.ppoll;
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p->reply[p->shift].status.stratum = msg.stratum;
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if (p->trustlevel < TRUSTLEVEL_PATHETIC)
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interval = scale_interval(INTERVAL_QUERY_PATHETIC);
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else if (p->trustlevel < TRUSTLEVEL_AGRESSIVE)
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interval = scale_interval(INTERVAL_QUERY_AGRESSIVE);
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else
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interval = scale_interval(INTERVAL_QUERY_NORMAL);
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set_next(p, interval);
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p->state = STATE_REPLY_RECEIVED;
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/* every received reply which we do not discard increases trust */
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if (p->trustlevel < TRUSTLEVEL_MAX) {
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if (p->trustlevel < TRUSTLEVEL_BADPEER &&
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p->trustlevel + 1 >= TRUSTLEVEL_BADPEER)
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log_info("peer %s now valid",
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log_sockaddr((struct sockaddr *)&p->addr->ss));
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p->trustlevel++;
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}
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log_debug("reply from %s: offset %f delay %f, "
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"next query %ds", log_sockaddr((struct sockaddr *)&p->addr->ss),
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p->reply[p->shift].offset, p->reply[p->shift].delay, interval);
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client_update(p);
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if (settime)
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priv_settime(p->reply[p->shift].offset);
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if (++p->shift >= OFFSET_ARRAY_SIZE)
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p->shift = 0;
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return (0);
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}
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int
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client_update(struct ntp_peer *p)
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{
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int i, best = 0, good = 0;
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/*
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* clock filter
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* find the offset which arrived with the lowest delay
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* use that as the peer update
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* invalidate it and all older ones
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*/
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for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++)
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if (p->reply[i].good) {
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good++;
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best = i;
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}
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for (; i < OFFSET_ARRAY_SIZE; i++)
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if (p->reply[i].good) {
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good++;
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if (p->reply[i].delay < p->reply[best].delay)
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best = i;
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}
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if (good < 8)
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return (-1);
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memcpy(&p->update, &p->reply[best], sizeof(p->update));
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priv_adjtime();
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for (i = 0; i < OFFSET_ARRAY_SIZE; i++)
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if (p->reply[i].rcvd <= p->reply[best].rcvd)
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p->reply[i].good = 0;
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return (0);
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}
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void
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client_log_error(struct ntp_peer *peer, const char *operation, int error)
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{
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const char *address;
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address = log_sockaddr((struct sockaddr *)&peer->addr->ss);
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if (peer->lasterror == error) {
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log_debug("%s %s: %s", operation, address, strerror(error));
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return;
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}
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peer->lasterror = error;
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log_warn("%s %s", operation, address);
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}
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