[git commit master] ntpd: locally bind every peer socket. +22 bytes
Denys Vlasenko
vda.linux at googlemail.com
Tue Nov 24 15:03:47 UTC 2009
commit: http://git.busybox.net/busybox/commit/?id=b1278a38bcb108fad3230ecce94a53b64571f9de
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
include/libbb.h | 3 +-
libbb/xconnect.c | 2 +-
networking/ntpd.c | 87 +++++++++++++++++++++++++++++++++++++----------------
3 files changed, 64 insertions(+), 28 deletions(-)
diff --git a/include/libbb.h b/include/libbb.h
index 77c9e28..1194f7e 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -490,7 +490,8 @@ enum {
/* Create stream socket, and allocate suitable lsa.
* (lsa of correct size and lsa->sa.sa_family (AF_INET/AF_INET6))
* af == AF_UNSPEC will result in trying to create IPv6 socket,
- * and if kernel doesn't support it, IPv4.
+ * and if kernel doesn't support it, fall back to IPv4.
+ * This is useful if you plan to bind to resulting local lsa.
*/
#if ENABLE_FEATURE_IPV6
int xsocket_type(len_and_sockaddr **lsap, int af, int sock_type) FAST_FUNC;
diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index b6848ea..8a1e1c1 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -346,7 +346,7 @@ int FAST_FUNC xsocket_type(len_and_sockaddr **lsap, IF_FEATURE_IPV6(int family,)
len = sizeof(struct sockaddr_in6);
}
#endif
- lsa = xzalloc(offsetof(len_and_sockaddr, u.sa) + len);
+ lsa = xzalloc(LSA_LEN_SIZE + len);
lsa->len = len;
lsa->u.sa.sa_family = family;
*lsap = lsa;
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 */
--
1.6.3.3
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