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ntp: check remote interval in client mode

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For testA in the client mode require also that the time the server
needed to process the client request is not longer than 4 seconds.
With maximum peer delay this limits the interval in which the client can
accept a server reply.
This commit is contained in:
Miroslav Lichvar 2015-11-04 15:47:40 +01:00
parent 66d534417b
commit df9b5d8c22
1 changed files with 7 additions and 3 deletions
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10
ntp_core.c
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@ -215,6 +215,9 @@ static ARR_Instance broadcasts;
/* Invalid stratum number */
#define NTP_INVALID_STRATUM 0
/* Maximum allowed time for server to process client packet */
#define MAX_SERVER_INTERVAL 4.0
/* Minimum and maximum allowed poll interval */
#define MIN_POLL 0
#define MAX_POLL 24
@ -1265,9 +1268,10 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
/* Additional tests required to pass before accumulating the sample */
/* Test A requires that the round trip delay is less than an
administrator-defined value */
testA = delay <= inst->max_delay;
/* Test A requires that the peer delay is not larger than the configured
maximum and in client mode also that the server processing time is sane */
testA = delay <= inst->max_delay &&
(inst->mode != MODE_CLIENT || remote_interval <= MAX_SERVER_INTERVAL);
/* Test B requires that the ratio of the round trip delay to the
minimum one currently in the stats data register is less than an