[MEDIUM] session counters: add conn_rate and sess_rate counters

These counters maintain incoming connection rates and session rates
in a stick-table, over a period which is defined in the configuration
(2 ms to 24 days). They can be used to detect service abuse and
enforce a certain accept rate per source address for instance, and
block if the rate is passed over.

Example :
	# block if more than 50 requests per 5 seconds from a source.
	stick-table type ip size 200k expire 1m store conn_rate(5s),sess_rate(5s)
	tcp-request track-counters src
	tcp-request reject if { trk_conn_rate gt 50 }

	# cause a 3 seconds pause to requests from sources in excess of 20 requests/5s
	tcp-request inspect-delay 3s
	tcp-request content accept if { trk_sess_rate gt 20 } WAIT_END
diff --git a/include/proto/session.h b/include/proto/session.h
index 6d5de3a..133e6c9 100644
--- a/include/proto/session.h
+++ b/include/proto/session.h
@@ -25,6 +25,7 @@
 #include <common/config.h>
 #include <common/memory.h>
 #include <types/session.h>
+#include <proto/freq_ctr.h>
 #include <proto/stick_table.h>
 
 extern struct pool_head *pool2_session;
@@ -81,6 +82,11 @@
 		if (ptr)
 			stktable_data_cast(ptr, conn_cnt)++;
 
+		ptr = stktable_data_ptr(t, ts, STKTABLE_DT_CONN_RATE);
+		if (ptr)
+			update_freq_ctr_period(&stktable_data_cast(ptr, conn_rate),
+					       t->data_arg[STKTABLE_DT_CONN_RATE].u, 1);
+
 		if (tick_isset(t->expire))
 			ts->expire = tick_add(now_ms, MS_TO_TICKS(t->expire));
 	}
diff --git a/include/types/stick_table.h b/include/types/stick_table.h
index caca0be..0501adc 100644
--- a/include/types/stick_table.h
+++ b/include/types/stick_table.h
@@ -30,6 +30,7 @@
 #include <ebmbtree.h>
 #include <eb32tree.h>
 #include <common/memory.h>
+#include <types/freq_ctr.h>
 
 /* stick table key types */
 enum {
@@ -43,8 +44,10 @@
 enum {
 	STKTABLE_DT_SERVER_ID,    /* the server ID to use with this session if > 0 */
 	STKTABLE_DT_CONN_CNT,     /* cumulated number of connections */
+	STKTABLE_DT_CONN_RATE,    /* incoming connection rate */
 	STKTABLE_DT_CONN_CUR,     /* concurrent number of connections */
 	STKTABLE_DT_SESS_CNT,     /* cumulated number of sessions (accepted connections) */
+	STKTABLE_DT_SESS_RATE,    /* accepted sessions rate */
 	STKTABLE_DT_BYTES_IN_CNT, /* cumulated bytes count from client to servers */
 	STKTABLE_DT_BYTES_OUT_CNT,/* cumulated bytes count from servers to client */
 	STKTABLE_DATA_TYPES       /* Number of data types, must always be last */
@@ -61,8 +64,10 @@
 union stktable_data {
 	int server_id;
 	unsigned int conn_cnt;
+	struct freq_ctr_period conn_rate;
 	unsigned int conn_cur;
 	unsigned int sess_cnt;
+	struct freq_ctr_period sess_rate;
 	unsigned long long bytes_in_cnt;
 	unsigned long long bytes_out_cnt;
 };
diff --git a/src/session.c b/src/session.c
index ed854d9..6c7a91d 100644
--- a/src/session.c
+++ b/src/session.c
@@ -26,6 +26,7 @@
 #include <proto/buffers.h>
 #include <proto/checks.h>
 #include <proto/dumpstats.h>
+#include <proto/freq_ctr.h>
 #include <proto/hdr_idx.h>
 #include <proto/log.h>
 #include <proto/session.h>
@@ -135,9 +136,16 @@
 		p->counters.feconn_max = p->feconn;
 	proxy_inc_fe_sess_ctr(l, p);
 	if (s->tracked_counters) {
-		void *ptr = stktable_data_ptr(s->tracked_table, s->tracked_counters, STKTABLE_DT_SESS_CNT);
+		void *ptr;
+
+		ptr = stktable_data_ptr(s->tracked_table, s->tracked_counters, STKTABLE_DT_SESS_CNT);
 		if (ptr)
 			stktable_data_cast(ptr, sess_cnt)++;
+
+		ptr = stktable_data_ptr(s->tracked_table, s->tracked_counters, STKTABLE_DT_SESS_RATE);
+		if (ptr)
+			update_freq_ctr_period(&stktable_data_cast(ptr, sess_rate),
+					       s->tracked_table->data_arg[STKTABLE_DT_SESS_RATE].u, 1);
 	}
 
 	/* this part should be common with other protocols */
@@ -2124,6 +2132,57 @@
 	return acl_fetch_conn_cnt(&px->table, test, stktable_lookup_key(&px->table, key));
 }
 
+/* set test->i to the connection rate in the stksess entry <ts> over the configured period */
+static int
+acl_fetch_conn_rate(struct stktable *table, struct acl_test *test, struct stksess *ts)
+{
+	test->flags = ACL_TEST_F_VOL_TEST;
+	test->i = 0;
+	if (ts != NULL) {
+		void *ptr = stktable_data_ptr(table, ts, STKTABLE_DT_CONN_RATE);
+		if (!ptr)
+			return 0; /* parameter not stored */
+		test->i = read_freq_ctr_period(&stktable_data_cast(ptr, conn_rate),
+					       table->data_arg[STKTABLE_DT_CONN_RATE].u);
+	}
+	return 1;
+}
+
+/* set test->i to the connection rate from the session's tracked counters over
+ * the configured period.
+ */
+static int
+acl_fetch_trk_conn_rate(struct proxy *px, struct session *l4, void *l7, int dir,
+			struct acl_expr *expr, struct acl_test *test)
+{
+	if (!l4->tracked_counters)
+		return 0;
+
+	return acl_fetch_conn_rate(l4->tracked_table, test, l4->tracked_counters);
+}
+
+/* set test->i to the connection rate from the session's source address in the
+ * table pointed to by expr, over the configured period.
+ */
+static int
+acl_fetch_src_conn_rate(struct proxy *px, struct session *l4, void *l7, int dir,
+			struct acl_expr *expr, struct acl_test *test)
+{
+	struct stktable_key *key;
+
+	key = tcpv4_src_to_stktable_key(l4);
+	if (!key)
+		return 0; /* only TCPv4 is supported right now */
+
+	if (expr->arg_len)
+		px = find_stktable(expr->arg.str);
+
+	if (!px)
+		return 0; /* table not found */
+
+	return acl_fetch_conn_rate(&px->table, test, stktable_lookup_key(&px->table, key));
+}
+
 /* set test->i to the number of connections from the session's source address
  * in the table pointed to by expr, after updating it.
  */
@@ -2261,6 +2320,57 @@
 	return acl_fetch_sess_cnt(&px->table, test, stktable_lookup_key(&px->table, key));
 }
 
+/* set test->i to the session rate in the stksess entry <ts> over the configured period */
+static int
+acl_fetch_sess_rate(struct stktable *table, struct acl_test *test, struct stksess *ts)
+{
+	test->flags = ACL_TEST_F_VOL_TEST;
+	test->i = 0;
+	if (ts != NULL) {
+		void *ptr = stktable_data_ptr(table, ts, STKTABLE_DT_SESS_RATE);
+		if (!ptr)
+			return 0; /* parameter not stored */
+		test->i = read_freq_ctr_period(&stktable_data_cast(ptr, sess_rate),
+					       table->data_arg[STKTABLE_DT_SESS_RATE].u);
+	}
+	return 1;
+}
+
+/* set test->i to the session rate from the session's tracked counters over
+ * the configured period.
+ */
+static int
+acl_fetch_trk_sess_rate(struct proxy *px, struct session *l4, void *l7, int dir,
+			struct acl_expr *expr, struct acl_test *test)
+{
+	if (!l4->tracked_counters)
+		return 0;
+
+	return acl_fetch_sess_rate(l4->tracked_table, test, l4->tracked_counters);
+}
+
+/* set test->i to the session rate from the session's source address in the
+ * table pointed to by expr, over the configured period.
+ */
+static int
+acl_fetch_src_sess_rate(struct proxy *px, struct session *l4, void *l7, int dir,
+			struct acl_expr *expr, struct acl_test *test)
+{
+	struct stktable_key *key;
+
+	key = tcpv4_src_to_stktable_key(l4);
+	if (!key)
+		return 0; /* only TCPv4 is supported right now */
+
+	if (expr->arg_len)
+		px = find_stktable(expr->arg.str);
+
+	if (!px)
+		return 0; /* table not found */
+
+	return acl_fetch_sess_rate(&px->table, test, stktable_lookup_key(&px->table, key));
+}
+
 /* set test->i to the number of kbytes received from clients matching the stksess entry <ts> */
 static int
 acl_fetch_kbytes_in(struct stktable *table, struct acl_test *test, struct stksess *ts)
@@ -2368,11 +2478,15 @@
 static struct acl_kw_list acl_kws = {{ },{
 	{ "trk_conn_cnt",       acl_parse_int,   acl_fetch_trk_conn_cnt,      acl_match_int, ACL_USE_NOTHING },
 	{ "src_conn_cnt",       acl_parse_int,   acl_fetch_src_conn_cnt,      acl_match_int, ACL_USE_TCP4_VOLATILE },
+	{ "trk_conn_rate",      acl_parse_int,   acl_fetch_trk_conn_rate,     acl_match_int, ACL_USE_NOTHING },
+	{ "src_conn_rate",      acl_parse_int,   acl_fetch_src_conn_rate,     acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "src_updt_conn_cnt",  acl_parse_int,   acl_fetch_src_updt_conn_cnt, acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "trk_conn_cur",       acl_parse_int,   acl_fetch_trk_conn_cur,      acl_match_int, ACL_USE_NOTHING },
 	{ "src_conn_cur",       acl_parse_int,   acl_fetch_src_conn_cur,      acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "trk_sess_cnt",       acl_parse_int,   acl_fetch_trk_sess_cnt,      acl_match_int, ACL_USE_NOTHING },
 	{ "src_sess_cnt",       acl_parse_int,   acl_fetch_src_sess_cnt,      acl_match_int, ACL_USE_TCP4_VOLATILE },
+	{ "trk_sess_rate",      acl_parse_int,   acl_fetch_trk_sess_rate,     acl_match_int, ACL_USE_NOTHING },
+	{ "src_sess_rate",      acl_parse_int,   acl_fetch_src_sess_rate,     acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "trk_kbytes_in",      acl_parse_int,   acl_fetch_trk_kbytes_in,     acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "src_kbytes_in",      acl_parse_int,   acl_fetch_src_kbytes_in,     acl_match_int, ACL_USE_TCP4_VOLATILE },
 	{ "trk_kbytes_out",     acl_parse_int,   acl_fetch_trk_kbytes_out,    acl_match_int, ACL_USE_TCP4_VOLATILE },
diff --git a/src/stick_table.c b/src/stick_table.c
index e68cae3..1801270 100644
--- a/src/stick_table.c
+++ b/src/stick_table.c
@@ -527,8 +527,10 @@
 struct stktable_data_type stktable_data_types[STKTABLE_DATA_TYPES] = {
 	[STKTABLE_DT_SERVER_ID] = { .name = "server_id", .data_length = stktable_data_size(server_id) },
 	[STKTABLE_DT_CONN_CNT]  = { .name = "conn_cnt",  .data_length = stktable_data_size(conn_cnt)  },
+	[STKTABLE_DT_CONN_RATE] = { .name = "conn_rate", .data_length = stktable_data_size(conn_rate), .arg_type = ARG_T_DELAY  },
 	[STKTABLE_DT_CONN_CUR]  = { .name = "conn_cur",  .data_length = stktable_data_size(conn_cur)  },
 	[STKTABLE_DT_SESS_CNT]  = { .name = "sess_cnt",  .data_length = stktable_data_size(sess_cnt)  },
+	[STKTABLE_DT_SESS_RATE] = { .name = "sess_rate", .data_length = stktable_data_size(sess_rate), .arg_type = ARG_T_DELAY  },
 	[STKTABLE_DT_BYTES_IN_CNT]  = { .name = "bytes_in_cnt",  .data_length = stktable_data_size(bytes_in_cnt)  },
 	[STKTABLE_DT_BYTES_OUT_CNT] = { .name = "bytes_out_cnt", .data_length = stktable_data_size(bytes_out_cnt) },
 };