implemented session count limiting

new config option:
[common]
max-sessions=N

If set then accel-pppd stops reply to new connection requests if total number of sessions (active and starting) is reached specified limit.

accel-pppd/accel-ppp.conf

@@ -40,6 +40,7 @@ thread-count=4
 #single-session=replace
 #sid-case=upper
 #sid-source=seq
+#max-sessions=1000
 
 [ppp]
 verbose=1

accel-pppd/ctrl/ipoe/ipoe.c

@@ -1190,6 +1190,12 @@ static struct ipoe_session *ipoe_session_create_dhcpv4(struct ipoe_serv *serv, s
 	int dlen = 0;
 	uint8_t *ptr = NULL;
 
+	if (ap_shutdown)
+		return NULL;
+
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return NULL;
+
 	ses = ipoe_session_alloc(serv->ifname);
 	if (!ses)
 		return NULL;
@@ -1790,6 +1796,9 @@ static struct ipoe_session *ipoe_session_create_up(struct ipoe_serv *serv, struc
 	if (ap_shutdown)
 		return NULL;
 
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return NULL;
+
 	if (l4_redirect_list_check(saddr))
 		return NULL;
 

accel-pppd/ctrl/l2tp/l2tp.c

@@ -2731,6 +2731,9 @@ static int l2tp_recv_SCCRQ(const struct l2tp_serv_t *serv,
 		return 0;
 	}
 
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return 0;
+
 	if (triton_module_loaded("connlimit")
 	    && connlimit_check(cl_key_from_ipv4(pack->addr.sin_addr.s_addr))) {
 		log_warn("l2tp: connection limits reached,"
@@ -3257,6 +3260,9 @@ static int l2tp_recv_ICRQ(struct l2tp_conn_t *conn,
 		return 0;
 	}
 
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return 0;
+
 	if (triton_module_loaded("connlimit")
 	    && connlimit_check(cl_key_from_ipv4(conn->peer_addr.sin_addr.s_addr))) {
 		log_tunnel(log_warn, conn, "connection limits reached,"
@@ -3557,6 +3563,9 @@ static int l2tp_recv_OCRQ(struct l2tp_conn_t *conn,
 		return 0;
 	}
 
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return 0;
+
 	if (triton_module_loaded("connlimit")
 	    && connlimit_check(cl_key_from_ipv4(conn->peer_addr.sin_addr.s_addr))) {
 		log_tunnel(log_warn, conn, "connection limits reached,"

accel-pppd/ctrl/pppoe/pppoe.c

@@ -949,6 +949,9 @@ static void pppoe_recv_PADI(struct pppoe_serv_t *serv, uint8_t *pack, int size)
 	if (ap_shutdown || pado_delay == -1)
 		return;
 
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return;
+
 	if (check_padi_limit(serv, ethhdr->h_source)) {
 		__sync_add_and_fetch(&stat_PADI_drop, 1);
 		if (conf_verbose) {
@@ -1068,6 +1071,9 @@ static void pppoe_recv_PADR(struct pppoe_serv_t *serv, uint8_t *pack, int size)
 	if (ap_shutdown)
 		return;
 
+	if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions)
+		return;
+
 	if (!memcmp(ethhdr->h_dest, bc_addr, ETH_ALEN)) {
 		if (conf_verbose)
 			log_warn("pppoe: discard PADR (destination address is broadcast)\n");

accel-pppd/ctrl/pptp/pptp.c

@@ -644,9 +644,14 @@ static int pptp_connect(struct triton_md_handler_t *h)
 			continue;
 		}
 
+		if (conf_max_sessions && ap_session_stat.active + ap_session_stat.starting >= conf_max_sessions) {
+			close(sock);
+			continue;
+		}
+
 		if (triton_module_loaded("connlimit") && connlimit_check(cl_key_from_ipv4(addr.sin_addr.s_addr))) {
 			close(sock);
-			return 0;
+			continue;
 		}
 
 		log_info2("pptp: new connection from %s\n", inet_ntoa(addr.sin_addr));

accel-pppd/include/ap_session.h

@@ -129,6 +129,7 @@ extern int sock_fd; // internet socket for ioctls
 extern int sock6_fd; // internet socket for ioctls
 extern int urandom_fd;
 extern struct ap_session_stat ap_session_stat;
+extern int conf_max_sessions;
 
 extern __thread const struct ap_net *net;
 extern const struct ap_net def_net;

accel-pppd/session.c

@@ -34,6 +34,7 @@ static int conf_single_session = -1;
 static int conf_sid_source;
 static int conf_seq_save_timeout = 10;
 static const char *conf_seq_file;
+int __export conf_max_sessions;
 
 pthread_rwlock_t __export ses_lock = PTHREAD_RWLOCK_INITIALIZER;
 __export LIST_HEAD(ses_list);
@@ -75,6 +76,10 @@ void __export ap_session_set_ifindex(struct ap_session *ses)
 		ses->acct_tx_packets_i = stats.tx_packets;
 		ses->acct_rx_bytes_i = stats.rx_bytes;
 		ses->acct_tx_bytes_i = stats.tx_bytes;
+		ses->acct_rx_bytes = 0;
+		ses->acct_tx_bytes = 0;
+		ses->acct_input_gigawords = 0;
+		ses->acct_output_gigawords = 0;
 	}
 }
 
@@ -507,6 +512,12 @@ static void load_config(void)
 	conf_seq_file = conf_get_opt("common", "seq-file");
 	if (!conf_seq_file)
 		conf_seq_file = "/var/lib/accel-ppp/seq";
+
+	opt = conf_get_opt("common", "max-sessions");
+	if (opt)
+		conf_max_sessions = atoi(opt);
+	else
+		conf_max_sessions = 0;
 }
 
 static void init(void)