diff options
Diffstat (limited to 'networking')
| -rw-r--r-- | networking/ntpd.c | 87 |
1 files changed, 61 insertions, 26 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c index 086b3ea..12e498d 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -12,22 +12,22 @@ # error "Sorry, your kernel has to support IP_PKTINFO" #endif -#define INTERVAL_QUERY_NORMAL 30 /* sync to peers every n secs */ -#define INTERVAL_QUERY_PATHETIC 60 -#define INTERVAL_QUERY_AGRESSIVE 5 +#define INTERVAL_QUERY_NORMAL 30 /* sync to peers every n secs */ +#define INTERVAL_QUERY_PATHETIC 60 +#define INTERVAL_QUERY_AGRESSIVE 5 -#define TRUSTLEVEL_BADPEER 6 /* bad if *less than* TRUSTLEVEL_BADPEER */ -#define TRUSTLEVEL_PATHETIC 2 -#define TRUSTLEVEL_AGRESSIVE 8 -#define TRUSTLEVEL_MAX 10 +#define TRUSTLEVEL_BADPEER 6 /* bad if *less than* TRUSTLEVEL_BADPEER */ +#define TRUSTLEVEL_PATHETIC 2 +#define TRUSTLEVEL_AGRESSIVE 8 +#define TRUSTLEVEL_MAX 10 -#define QSCALE_OFF_MIN 0.05 -#define QSCALE_OFF_MAX 0.50 +#define QSCALE_OFF_MIN 0.05 +#define QSCALE_OFF_MAX 0.50 -#define QUERYTIME_MAX 15 /* single query might take n secs max */ -#define OFFSET_ARRAY_SIZE 8 -#define SETTIME_MIN_OFFSET 180 /* min offset for settime at start */ -#define SETTIME_TIMEOUT 15 /* max seconds to wait with -s */ +#define QUERYTIME_MAX 15 /* single query might take n secs max */ +#define OFFSET_ARRAY_SIZE 8 +#define SETTIME_MIN_OFFSET 180 /* min offset for settime at start */ +#define SETTIME_TIMEOUT 15 /* max seconds to wait with -s */ /* Style borrowed from NTP ref/tcpdump and updated for SNTPv4 (RFC2030). */ @@ -112,7 +112,7 @@ enum { MODE_RES2 = 7, /* reserved for private use */ }; -#define JAN_1970 2208988800UL /* 1970 - 1900 in seconds */ +#define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */ enum client_state { STATE_NONE, @@ -173,12 +173,12 @@ struct globals { #if ENABLE_FEATURE_NTPD_SERVER int listen_fd; #endif + unsigned peer_cnt; llist_t *ntp_peers; ntp_status_t status; uint32_t scale; uint8_t settime; uint8_t firstadj; - smallint peer_cnt; }; #define G (*ptr_to_globals) @@ -214,11 +214,11 @@ add_peers(const char *s) } static double -gettime_fp(void) +gettime1900fp(void) { struct timeval tv; gettimeofday(&tv, NULL); /* never fails */ - return (tv.tv_sec + 1.0e-6 * tv.tv_usec + JAN_1970); + return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970); } static void @@ -311,12 +311,43 @@ sendmsg_wrap(int fd, static int send_query_to_peer(ntp_peer_t *p) { + // Why do we need to bind()? + // See what happens when we don't bind: + // + // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3 + // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0 + // gettimeofday({1259071266, 327885}, NULL) = 0 + // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48 + // ^^^ we sent it from some source port picked by kernel. + // time(NULL) = 1259071266 + // write(2, "ntpd: entering poll 15 secs\n", 28) = 28 + // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}]) + // recv(3, "yyy", 68, MSG_DONTWAIT) = 48 + // ^^^ this recv will receive packets to any local port! + // + // Uncomment this and use strace to see it in action: +#define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } + if (p->query.fd == -1) { - p->query.fd = xsocket(p->lsa->u.sa.sa_family, SOCK_DGRAM, 0); + int fd, family; + len_and_sockaddr *local_lsa; + + family = p->lsa->u.sa.sa_family; + //was: p->query.fd = xsocket(family, SOCK_DGRAM, 0); + p->query.fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM); + /* local_lsa has "null" address and port 0 now. + * bind() ensures we have a *particular port* selected by kernel + * and remembered in p->query.fd, thus later recv(p->query.fd) + * receives only packets sent to this port. + */ + PROBE_LOCAL_ADDR + xbind(fd, &local_lsa->u.sa, local_lsa->len); + PROBE_LOCAL_ADDR #if ENABLE_FEATURE_IPV6 - if (p->lsa->u.sa.sa_family == AF_INET) + if (family == AF_INET) #endif - setsockopt(p->query.fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY)); + setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY)); + free(local_lsa); } /* @@ -335,7 +366,7 @@ send_query_to_peer(ntp_peer_t *p) p->query.msg.xmttime.int_partl = random(); p->query.msg.xmttime.fractionl = random(); - p->query.xmttime = gettime_fp(); + p->query.xmttime = gettime1900fp(); if (sendmsg_wrap(p->query.fd, /*from:*/ NULL, /*to:*/ &p->lsa->u.sa, /*addrlen:*/ p->lsa->len, &p->query.msg, NTP_MSGSIZE_NOAUTH) == -1) { @@ -437,7 +468,7 @@ adjtime_wrap(void) } G.firstadj = 0; - G.status.reftime = gettime_fp(); + G.status.reftime = gettime1900fp(); G.status.stratum++; /* one more than selected peer */ G.scale = updated_scale(offset_median); @@ -568,6 +599,10 @@ recv_and_process_peer_pkt(ntp_peer_t *p) addr = xmalloc_sockaddr2dotted_noport(&p->lsa->u.sa); + /* We can recvfrom here and check from.IP, but some multihomed + * ntp servers reply from their *other IP*. + * TODO: maybe we should check at least what we can: from.port == 123? + */ size = recv(p->query.fd, &msg, sizeof(msg), MSG_DONTWAIT); if (size == -1) { bb_perror_msg("recv(%s) error", addr); @@ -583,7 +618,7 @@ recv_and_process_peer_pkt(ntp_peer_t *p) xfunc_die(); } - T4 = gettime_fp(); + T4 = gettime1900fp(); if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) { bb_error_msg("malformed packet received from %s", addr); @@ -635,7 +670,7 @@ recv_and_process_peer_pkt(ntp_peer_t *p) goto bail; } offset->error = (T2 - T1) - (T3 - T4); -// Can we use (T4 - JAN_1970) instead of time(NULL)? +// Can we use (T4 - OFFSET_1900_1970) instead of time(NULL)? offset->rcvd = time(NULL); offset->good = 1; @@ -724,10 +759,10 @@ recv_and_process_client_pkt(void /*int fd*/) msg.stratum = G.status.stratum; msg.ppoll = query_ppoll; msg.precision = G.status.precision; - rectime = gettime_fp(); + rectime = gettime1900fp(); msg.xmttime = msg.rectime = d_to_lfp(rectime); msg.reftime = d_to_lfp(G.status.reftime); - //msg.xmttime = d_to_lfp(gettime_fp()); // = msg.rectime + //msg.xmttime = d_to_lfp(gettime1900fp()); // = msg.rectime msg.orgtime = query_xmttime; msg.rootdelay = d_to_sfp(G.status.rootdelay); version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */ |