kike: add a trivial flood detector
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parent
126c07b70a
commit
b8f002eaf5
53
kike.c
53
kike.c
@ -92,6 +92,49 @@ setup_signal_handlers (void)
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exit_fatal ("%s: %s", "sigaction", strerror (errno));
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}
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// --- Rate limiter ------------------------------------------------------------
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struct flood_detector
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{
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unsigned interval; ///< Interval for the limit
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unsigned limit; ///< Maximum number of events allowed
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time_t *timestamps; ///< Timestamps of last events
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unsigned pos; ///< Index of the oldest event
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};
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static void
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flood_detector_init (struct flood_detector *self,
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unsigned interval, unsigned limit)
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{
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self->interval = interval;
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self->limit = limit;
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self->timestamps = xcalloc (limit + 1, sizeof *self->timestamps);
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self->pos = 0;
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}
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static void
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flood_detector_free (struct flood_detector *self)
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{
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free (self->timestamps);
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}
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static bool
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flood_detector_check (struct flood_detector *self)
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{
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time_t now = time (NULL);
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self->timestamps[self->pos++] = now;
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if (self->pos > self->limit)
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self->pos = 0;
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time_t begin = now - self->interval;
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size_t count = 0;
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for (size_t i = 0; i <= self->limit; i++)
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if (self->timestamps[i] >= begin)
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count++;
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return count <= self->limit;
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}
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// --- IRC token validation ----------------------------------------------------
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// Use the enum only if applicable and a simple boolean isn't sufficient.
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@ -277,6 +320,7 @@ struct client
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unsigned mode; ///< User's mode
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char *away_message; ///< Away message
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time_t last_active; ///< Last PRIVMSG, to get idle time
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struct flood_detector antiflood; ///< Flood detector
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};
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static void
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@ -287,6 +331,8 @@ client_init (struct client *self)
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self->socket_fd = -1;
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str_init (&self->read_buffer);
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str_init (&self->write_buffer);
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// TODO: make this configurable and more fine-grained
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flood_detector_init (&self->antiflood, 10, 20);
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}
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static void
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@ -306,6 +352,7 @@ client_free (struct client *self)
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free (self->hostname);
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free (self->away_message);
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flood_detector_free (&self->antiflood);
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}
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static void client_close_link (struct client *, const char *);
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@ -2299,6 +2346,12 @@ irc_process_message (const struct irc_message *msg,
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if (c->closing_link)
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return;
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if (!flood_detector_check (&c->antiflood))
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{
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client_close_link (c, "Excess flood");
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return;
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}
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struct irc_command *cmd = str_map_find (&c->ctx->handlers, msg->command);
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if (!cmd)
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irc_send_reply (c, IRC_ERR_UNKNOWNCOMMAND, msg->command);
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