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b1278a38b

Denys Vlasenko

2009-11-24

FAILED Duration: 27s

Subject

ntpd: locally bind every peer socket. +22 bytes

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

include/libbb.h +2 -1 libbb/xconnect.c +1 -1 networking/ntpd.c +61 -26

include/libbb.h+2 -1

@@ -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;

libbb/xconnect.c+1 -1

@@ -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;

networking/ntpd.c+61 -26

@@ -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 */