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clientlog: limit response rate

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When the measured NTP or command request rate of a client exceeds
a threshold, reply only to a small fraction of the requests to reduce
the network traffic. Clients are allowed to send a burst of requests.
Try to detect broken clients which increase the request rate when not
getting replies and suppress the rate limiting for them.

Add ratelimit and cmdratelimit directives to configure the thresholds,
bursts and leak rates independently for NTP and command response rate
limiting. Both are disabled by default. Commands from localhost are
never limited.
This commit is contained in:
Miroslav Lichvar
2015-11-25 13:23:52 +01:00
parent 830135edea
commit b506594c2d
6 changed files with 273 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

67
conf.c
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@@ -70,6 +70,8 @@ static void parse_makestep(char *);
static void parse_maxchange(char *);
static void parse_peer(char *);
static void parse_pool(char *);
static void parse_ratelimit(char *line, int *enabled, int *interval,
int *burst, int *leak);
static void parse_refclock(char *);
static void parse_server(char *);
static void parse_smoothtime(char *);
@@ -187,6 +189,16 @@ static char *bind_cmd_path;
* chronyds being started. */
static char *pidfile;
/* Rate limiting parameters */
static int ntp_ratelimit_enabled = 0;
static int ntp_ratelimit_interval = 3;
static int ntp_ratelimit_burst = 7;
static int ntp_ratelimit_leak = 3;
static int cmd_ratelimit_enabled = 0;
static int cmd_ratelimit_interval = 1;
static int cmd_ratelimit_burst = 50;
static int cmd_ratelimit_leak = 1;
/* Smoothing constants */
static double smooth_max_freq = 0.0; /* in ppm */
static double smooth_max_wander = 0.0; /* in ppm/s */
@@ -431,6 +443,9 @@ CNF_ParseLine(const char *filename, int number, char *line)
parse_cmddeny(p);
} else if (!strcasecmp(command, "cmdport")) {
parse_int(p, &cmd_port);
} else if (!strcasecmp(command, "cmdratelimit")) {
parse_ratelimit(p, &cmd_ratelimit_enabled, &cmd_ratelimit_interval,
&cmd_ratelimit_burst, &cmd_ratelimit_leak);
} else if (!strcasecmp(command, "combinelimit")) {
parse_double(p, &combine_limit);
} else if (!strcasecmp(command, "corrtimeratio")) {
@@ -501,6 +516,9 @@ CNF_ParseLine(const char *filename, int number, char *line)
parse_pool(p);
} else if (!strcasecmp(command, "port")) {
parse_int(p, &ntp_port);
} else if (!strcasecmp(command, "ratelimit")) {
parse_ratelimit(p, &ntp_ratelimit_enabled, &ntp_ratelimit_interval,
&ntp_ratelimit_burst, &ntp_ratelimit_leak);
} else if (!strcasecmp(command, "refclock")) {
parse_refclock(p);
} else if (!strcasecmp(command, "reselectdist")) {
@@ -632,6 +650,35 @@ parse_pool(char *line)
/* ================================================== */
static void
parse_ratelimit(char *line, int *enabled, int *interval, int *burst, int *leak)
{
int n, val;
char *opt;
*enabled = 1;
while (*line) {
opt = line;
line = CPS_SplitWord(line);
if (sscanf(line, "%d%n", &val, &n) != 1) {
command_parse_error();
return;
}
line += n;
if (!strcasecmp(opt, "interval"))
*interval = val;
else if (!strcasecmp(opt, "burst"))
*burst = val;
else if (!strcasecmp(opt, "leak"))
*leak = val;
else
command_parse_error();
}
}
/* ================================================== */
static void
parse_refclock(char *line)
{
@@ -1785,6 +1832,26 @@ CNF_GetLockMemory(void)
/* ================================================== */
int CNF_GetNTPRateLimit(int *interval, int *burst, int *leak)
{
*interval = ntp_ratelimit_interval;
*burst = ntp_ratelimit_burst;
*leak = ntp_ratelimit_leak;
return ntp_ratelimit_enabled;
}
/* ================================================== */
int CNF_GetCommandRateLimit(int *interval, int *burst, int *leak)
{
*interval = cmd_ratelimit_interval;
*burst = cmd_ratelimit_burst;
*leak = cmd_ratelimit_leak;
return cmd_ratelimit_enabled;
}
/* ================================================== */
void
CNF_GetSmooth(double *max_freq, double *max_wander, int *leap_only)
{