zebra: refactor zserv names, consolidate events

* Add centralized thread scheduling dispatchers for client threads and
  the main thread

* Rename everything in zserv.c to stop using a combination of:
  - zebra_server_*
  - zebra_*
  - zserv_*

  Everything in zserv.c now begins with zserv_*.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

13 files changed, 223 insertions, 113 deletions

diff --git a/zebra/label_manager.c b/zebra/label_manager.c
index f3fa3ba94..9bfc4001b 100644
--- a/zebra/label_manager.c
+++ b/zebra/label_manager.c
@@ -350,7 +350,7 @@ void label_manager_init(char *lm_zserv_path)
 
 	obuf = stream_new(ZEBRA_MAX_PACKET_SIZ);
 
-	hook_register(zapi_client_close, release_daemon_label_chunks);
+	hook_register(zserv_client_close, release_daemon_label_chunks);
 }
 
 /**
diff --git a/zebra/main.c b/zebra/main.c
index 9bcbaa3c2..c5246999f 100644
--- a/zebra/main.c
+++ b/zebra/main.c
@@ -379,10 +379,11 @@ int main(int argc, char **argv)
 	/* Needed for BSD routing socket. */
 	pid = getpid();
 
+	/* Intialize pthread library */
 	frr_pthread_init();
 
-	/* This must be done only after locking pidfile (bug #403). */
-	zebra_zserv_socket_init(zserv_path);
+	/* Start Zebra API server */
+	zserv_start(zserv_path);
 
 	/* Init label manager */
 	label_manager_init(lblmgr_path);
diff --git a/zebra/table_manager.c b/zebra/table_manager.c
index cb8c38443..5bcc2c40d 100644
--- a/zebra/table_manager.c
+++ b/zebra/table_manager.c
@@ -78,7 +78,7 @@ void table_manager_enable(ns_id_t ns_id)
 		return;
 	tbl_mgr.lc_list = list_new();
 	tbl_mgr.lc_list->del = delete_table_chunk;
-	hook_register(zapi_client_close, release_daemon_table_chunks);
+	hook_register(zserv_client_close, release_daemon_table_chunks);
 }
 
 /**
diff --git a/zebra/zapi_msg.c b/zebra/zapi_msg.c
index 943329b19..2c19f31c7 100644
--- a/zebra/zapi_msg.c
+++ b/zebra/zapi_msg.c
@@ -162,7 +162,7 @@ int zsend_interface_add(struct zserv *client, struct interface *ifp)
 	zserv_encode_interface(s, ifp);
 
 	client->ifadd_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* Interface deletion from zebra daemon. */
@@ -174,7 +174,7 @@ int zsend_interface_delete(struct zserv *client, struct interface *ifp)
 	zserv_encode_interface(s, ifp);
 
 	client->ifdel_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 int zsend_vrf_add(struct zserv *client, struct zebra_vrf *zvrf)
@@ -185,7 +185,7 @@ int zsend_vrf_add(struct zserv *client, struct zebra_vrf *zvrf)
 	zserv_encode_vrf(s, zvrf);
 
 	client->vrfadd_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* VRF deletion from zebra daemon. */
@@ -198,7 +198,7 @@ int zsend_vrf_delete(struct zserv *client, struct zebra_vrf *zvrf)
 	zserv_encode_vrf(s, zvrf);
 
 	client->vrfdel_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 int zsend_interface_link_params(struct zserv *client, struct interface *ifp)
@@ -230,7 +230,7 @@ int zsend_interface_link_params(struct zserv *client, struct interface *ifp)
 	/* Write packet size. */
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* Interface address is added/deleted. Send ZEBRA_INTERFACE_ADDRESS_ADD or
@@ -309,7 +309,7 @@ int zsend_interface_address(int cmd, struct zserv *client,
 	stream_putw_at(s, 0, stream_get_endp(s));
 
 	client->connected_rt_add_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 static int zsend_interface_nbr_address(int cmd, struct zserv *client,
@@ -340,7 +340,7 @@ static int zsend_interface_nbr_address(int cmd, struct zserv *client,
 	/* Write packet size. */
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* Interface address addition. */
@@ -438,7 +438,7 @@ int zsend_interface_vrf_update(struct zserv *client, struct interface *ifp,
 	stream_putw_at(s, 0, stream_get_endp(s));
 
 	client->if_vrfchg_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* Add new nbr connected IPv6 address */
@@ -511,7 +511,7 @@ int zsend_interface_update(int cmd, struct zserv *client, struct interface *ifp)
 	else
 		client->ifdown_cnt++;
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 int zsend_redistribute_route(int cmd, struct zserv *client, struct prefix *p,
@@ -602,7 +602,7 @@ int zsend_redistribute_route(int cmd, struct zserv *client, struct prefix *p,
 			   zebra_route_string(api.type), api.vrf_id,
 			   buf_prefix);
 	}
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -655,7 +655,7 @@ static int zsend_ipv4_nexthop_lookup_mrib(struct zserv *client,
 
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 int zsend_route_notify_owner(struct route_entry *re, struct prefix *p,
@@ -665,7 +665,7 @@ int zsend_route_notify_owner(struct route_entry *re, struct prefix *p,
 	struct stream *s;
 	uint8_t blen;
 
-	client = zebra_find_client(re->type, re->instance);
+	client = zserv_find_client(re->type, re->instance);
 	if (!client || !client->notify_owner) {
 		if (IS_ZEBRA_DEBUG_PACKET) {
 			char buff[PREFIX_STRLEN];
@@ -703,7 +703,7 @@ int zsend_route_notify_owner(struct route_entry *re, struct prefix *p,
 
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 void zsend_rule_notify_owner(struct zebra_pbr_rule *rule,
@@ -739,7 +739,7 @@ void zsend_rule_notify_owner(struct zebra_pbr_rule *rule,
 
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	zebra_server_send_message(client, s);
+	zserv_send_message(client, s);
 }
 
 void zsend_ipset_notify_owner(struct zebra_pbr_ipset *ipset,
@@ -769,7 +769,7 @@ void zsend_ipset_notify_owner(struct zebra_pbr_ipset *ipset,
 	stream_put(s, ipset->ipset_name, ZEBRA_IPSET_NAME_SIZE);
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	zebra_server_send_message(client, s);
+	zserv_send_message(client, s);
 }
 
 void zsend_ipset_entry_notify_owner(struct zebra_pbr_ipset_entry *ipset,
@@ -799,7 +799,7 @@ void zsend_ipset_entry_notify_owner(struct zebra_pbr_ipset_entry *ipset,
 	stream_put(s, ipset->backpointer->ipset_name, ZEBRA_IPSET_NAME_SIZE);
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	zebra_server_send_message(client, s);
+	zserv_send_message(client, s);
 }
 
 void zsend_iptable_notify_owner(struct zebra_pbr_iptable *iptable,
@@ -828,7 +828,7 @@ void zsend_iptable_notify_owner(struct zebra_pbr_iptable *iptable,
 	stream_putl(s, iptable->unique);
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	zebra_server_send_message(client, s);
+	zserv_send_message(client, s);
 }
 
 /* Router-id is updated. Send ZEBRA_ROUTER_ID_ADD to client. */
@@ -855,7 +855,7 @@ int zsend_router_id_update(struct zserv *client, struct prefix *p,
 	/* Write packet size. */
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -873,7 +873,7 @@ int zsend_pw_update(struct zserv *client, struct zebra_pw *pw)
 	/* Put length at the first point of the stream. */
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* Send response to a get label chunk request to client */
@@ -952,7 +952,7 @@ static int zsend_assign_table_chunk_response(struct zserv *client,
 	/* Write packet size. */
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 static int zsend_table_manager_connect_response(struct zserv *client,
@@ -968,7 +968,7 @@ static int zsend_table_manager_connect_response(struct zserv *client,
 
 	stream_putw_at(s, 0, stream_get_endp(s));
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* Inbound message handling ------------------------------------------------ */
@@ -2194,7 +2194,7 @@ static void zsend_capabilities(struct zserv *client, struct zebra_vrf *zvrf)
 	stream_putl(s, multipath_num);
 
 	stream_putw_at(s, 0, stream_get_endp(s));
-	zebra_server_send_message(client, s);
+	zserv_send_message(client, s);
 }
 
 /* Tie up route-type and client->sock */
diff --git a/zebra/zebra_mpls.c b/zebra/zebra_mpls.c
index 3ad640653..e040808e0 100644
--- a/zebra/zebra_mpls.c
+++ b/zebra/zebra_mpls.c
@@ -463,7 +463,7 @@ static int fec_send(zebra_fec_t *fec, struct zserv *client)
 	stream_put_prefix(s, &rn->p);
 	stream_putl(s, fec->label);
 	stream_putw_at(s, 0, stream_get_endp(s));
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -2916,5 +2916,5 @@ void zebra_mpls_init(void)
 	if (!mpls_processq_init(&zebrad))
 		mpls_enabled = 1;
 
-	hook_register(zapi_client_close, zebra_mpls_cleanup_fecs_for_client);
+	hook_register(zserv_client_close, zebra_mpls_cleanup_fecs_for_client);
 }
diff --git a/zebra/zebra_mroute.c b/zebra/zebra_mroute.c
index 042bd3769..3af3cd5bb 100644
--- a/zebra/zebra_mroute.c
+++ b/zebra/zebra_mroute.c
@@ -67,5 +67,5 @@ stream_failure:
 	stream_putl(s, suc);
 
 	stream_putw_at(s, 0, stream_get_endp(s));
-	zebra_server_send_message(client, s);
+	zserv_send_message(client, s);
 }
diff --git a/zebra/zebra_ptm.c b/zebra/zebra_ptm.c
index d20f93f52..8c23bf34c 100644
--- a/zebra/zebra_ptm.c
+++ b/zebra/zebra_ptm.c
@@ -126,7 +126,7 @@ void zebra_ptm_init(void)
 
 	ptm_cb.ptm_sock = -1;
 
-	hook_register(zapi_client_close, zebra_ptm_bfd_client_deregister);
+	hook_register(zserv_client_close, zebra_ptm_bfd_client_deregister);
 }
 
 void zebra_ptm_finish(void)
diff --git a/zebra/zebra_ptm_redistribute.c b/zebra/zebra_ptm_redistribute.c
index 747714769..815f61d15 100644
--- a/zebra/zebra_ptm_redistribute.c
+++ b/zebra/zebra_ptm_redistribute.c
@@ -66,7 +66,7 @@ static int zsend_interface_bfd_update(int cmd, struct zserv *client,
 	stream_putw_at(s, 0, stream_get_endp(s));
 
 	client->if_bfd_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 void zebra_interface_bfd_update(struct interface *ifp, struct prefix *dp,
@@ -101,7 +101,7 @@ static int zsend_bfd_peer_replay(int cmd, struct zserv *client)
 	stream_putw_at(s, 0, stream_get_endp(s));
 
 	client->bfd_peer_replay_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 void zebra_bfd_peer_replay_req(void)
diff --git a/zebra/zebra_pw.c b/zebra/zebra_pw.c
index 28e09fe19..bf76f7e86 100644
--- a/zebra/zebra_pw.c
+++ b/zebra/zebra_pw.c
@@ -292,7 +292,7 @@ void zebra_pw_init(struct zebra_vrf *zvrf)
 	RB_INIT(zebra_pw_head, &zvrf->pseudowires);
 	RB_INIT(zebra_static_pw_head, &zvrf->static_pseudowires);
 
-	hook_register(zapi_client_close, zebra_pw_client_close);
+	hook_register(zserv_client_close, zebra_pw_client_close);
 }
 
 void zebra_pw_exit(struct zebra_vrf *zvrf)
diff --git a/zebra/zebra_rnh.c b/zebra/zebra_rnh.c
index 90c39bcc6..d482e0ab3 100644
--- a/zebra/zebra_rnh.c
+++ b/zebra/zebra_rnh.c
@@ -73,7 +73,7 @@ int zebra_rnh_ipv6_default_route = 0;
 
 void zebra_rnh_init(void)
 {
-	hook_register(zapi_client_close, zebra_client_cleanup_rnh);
+	hook_register(zserv_client_close, zebra_client_cleanup_rnh);
 }
 
 static inline struct route_table *get_rnh_table(vrf_id_t vrfid, int family,
@@ -1106,7 +1106,7 @@ static int send_client(struct rnh *rnh, struct zserv *client, rnh_type_t type,
 
 	client->nh_last_upd_time = monotime(NULL);
 	client->last_write_cmd = cmd;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 static void print_nh(struct nexthop *nexthop, struct vty *vty)
diff --git a/zebra/zebra_vxlan.c b/zebra/zebra_vxlan.c
index 90604215e..c6adc89e5 100644
--- a/zebra/zebra_vxlan.c
+++ b/zebra/zebra_vxlan.c
@@ -1195,7 +1195,7 @@ static int zvni_macip_send_msg_to_client(vni_t vni, struct ethaddr *macaddr,
 	struct zserv *client = NULL;
 	struct stream *s = NULL;
 
-	client = zebra_find_client(ZEBRA_ROUTE_BGP, 0);
+	client = zserv_find_client(ZEBRA_ROUTE_BGP, 0);
 	/* BGP may not be running. */
 	if (!client)
 		return 0;
@@ -1237,7 +1237,7 @@ static int zvni_macip_send_msg_to_client(vni_t vni, struct ethaddr *macaddr,
 	else
 		client->macipdel_cnt++;
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -2779,7 +2779,7 @@ static int zvni_send_add_to_client(zebra_vni_t *zvni)
 	struct zserv *client;
 	struct stream *s;
 
-	client = zebra_find_client(ZEBRA_ROUTE_BGP, 0);
+	client = zserv_find_client(ZEBRA_ROUTE_BGP, 0);
 	/* BGP may not be running. */
 	if (!client)
 		return 0;
@@ -2801,7 +2801,7 @@ static int zvni_send_add_to_client(zebra_vni_t *zvni)
 			   zebra_route_string(client->proto));
 
 	client->vniadd_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -2812,7 +2812,7 @@ static int zvni_send_del_to_client(vni_t vni)
 	struct zserv *client;
 	struct stream *s;
 
-	client = zebra_find_client(ZEBRA_ROUTE_BGP, 0);
+	client = zserv_find_client(ZEBRA_ROUTE_BGP, 0);
 	/* BGP may not be running. */
 	if (!client)
 		return 0;
@@ -2831,7 +2831,7 @@ static int zvni_send_del_to_client(vni_t vni)
 			   zebra_route_string(client->proto));
 
 	client->vnidel_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -3745,7 +3745,7 @@ static int zl3vni_send_add_to_client(zebra_l3vni_t *zl3vni)
 	struct ethaddr rmac;
 	char buf[ETHER_ADDR_STRLEN];
 
-	client = zebra_find_client(ZEBRA_ROUTE_BGP, 0);
+	client = zserv_find_client(ZEBRA_ROUTE_BGP, 0);
 	/* BGP may not be running. */
 	if (!client)
 		return 0;
@@ -3777,7 +3777,7 @@ static int zl3vni_send_add_to_client(zebra_l3vni_t *zl3vni)
 			zebra_route_string(client->proto));
 
 	client->l3vniadd_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /*
@@ -3788,7 +3788,7 @@ static int zl3vni_send_del_to_client(zebra_l3vni_t *zl3vni)
 	struct stream *s = NULL;
 	struct zserv *client = NULL;
 
-	client = zebra_find_client(ZEBRA_ROUTE_BGP, 0);
+	client = zserv_find_client(ZEBRA_ROUTE_BGP, 0);
 	/* BGP may not be running. */
 	if (!client)
 		return 0;
@@ -3807,7 +3807,7 @@ static int zl3vni_send_del_to_client(zebra_l3vni_t *zl3vni)
 			   zebra_route_string(client->proto));
 
 	client->l3vnidel_cnt++;
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 static void zebra_vxlan_process_l3vni_oper_up(zebra_l3vni_t *zl3vni)
@@ -3920,7 +3920,7 @@ static int ip_prefix_send_to_client(vrf_id_t vrf_id, struct prefix *p,
 	struct stream *s = NULL;
 	char buf[PREFIX_STRLEN];
 
-	client = zebra_find_client(ZEBRA_ROUTE_BGP, 0);
+	client = zserv_find_client(ZEBRA_ROUTE_BGP, 0);
 	/* BGP may not be running. */
 	if (!client)
 		return 0;
@@ -3944,7 +3944,7 @@ static int ip_prefix_send_to_client(vrf_id_t vrf_id, struct prefix *p,
 	else
 		client->prefixdel_cnt++;
 
-	return zebra_server_send_message(client, s);
+	return zserv_send_message(client, s);
 }
 
 /* re-add remote rmac if needed */
diff --git a/zebra/zserv.c b/zebra/zserv.c
index f2a2bdcb8..9e2c44376 100644
--- a/zebra/zserv.c
+++ b/zebra/zserv.c
@@ -69,14 +69,65 @@ extern struct zebra_privs_t zserv_privs;
  *
  * These are used almost exclusively by client threads to drive their own event
  * loops. The only exception is in zebra_client_create(), which pushes an
- * initial ZEBRA_READ event to start the API handler loop.
+ * initial ZSERV_CLIENT_READ event to start the API handler loop.
  */
-enum event { ZEBRA_READ, ZEBRA_WRITE };
+enum zserv_client_event {
+	/* Schedule a socket read */
+	ZSERV_CLIENT_READ,
+	/* Schedule a buffer write */
+	ZSERV_CLIENT_WRITE,
+	/* Schedule a buffer flush */
+	ZSERV_CLIENT_FLUSH_DATA,
+};
 
-/* Forward declarations for functions used from both threads. */
-static void zebra_event(struct zserv *client, enum event event);
-static int zebra_client_handle_close(struct thread *thread);
-static int zserv_process_messages(struct thread *thread);
+/*
+ * Main thread events.
+ *
+ * These are used by client threads to notify the main thread about various
+ * events and to make processing requests.
+ */
+enum zserv_event {
+	/* Schedule listen job on Zebra API socket */
+	ZSERV_ACCEPT,
+	/* The calling client has packets on its input buffer */
+	ZSERV_PROCESS_MESSAGES,
+	/* The calling client wishes to be killed */
+	ZSERV_HANDLE_CLOSE,
+};
+
+/*
+ * Zebra server event driver for all client threads.
+ *
+ * This is essentially a wrapper around thread_add_event() that centralizes
+ * those scheduling calls into one place.
+ *
+ * All calls to this function schedule an event on the pthread running the
+ * provided client.
+ *
+ * client
+ *    the client in question, and thread target
+ *
+ * event
+ *    the event to notify them about
+ */
+static void zserv_client_event(struct zserv *client,
+			       enum zserv_client_event event);
+
+/*
+ * Zebra server event driver for the main thread.
+ *
+ * This is essentially a wrapper around thread_add_event() that centralizes
+ * those scheduling calls into one place.
+ *
+ * All calls to this function schedule an event on Zebra's main pthread.
+ *
+ * client
+ *    the client in question
+ *
+ * event
+ *    the event to notify the main thread about
+ */
+static void zserv_event(struct zserv *client, enum zserv_event event);
 
 
 /* Client thread lifecycle -------------------------------------------------- */
@@ -107,7 +158,6 @@ static void zserv_log_message(const char *errmsg, struct stream *msg,
 	zlog_hexdump(msg->data, STREAM_READABLE(msg));
 }
 
-
 /*
  * Gracefully shut down a client connection.
  *
@@ -116,12 +166,11 @@ static void zserv_log_message(const char *errmsg, struct stream *msg,
  *
  * Must be called from the client pthread, never the main thread.
  */
-static void zebra_client_close(struct zserv *client)
+static void zserv_client_close(struct zserv *client)
 {
 	THREAD_OFF(client->t_read);
 	THREAD_OFF(client->t_write);
-	thread_add_event(zebrad.master, zebra_client_handle_close, client, 0,
-			 NULL);
+	zserv_event(client, ZSERV_HANDLE_CLOSE);
 }
 
 static int zserv_flush_data(struct thread *thread)
@@ -134,13 +183,11 @@ static int zserv_flush_data(struct thread *thread)
 		zlog_warn(
 			"%s: buffer_flush_available failed on zserv client fd %d, closing",
 			__func__, client->sock);
-		zebra_client_close(client);
+		zserv_client_close(client);
 		client = NULL;
 		break;
 	case BUFFER_PENDING:
-		client->t_write = NULL;
-		thread_add_write(client->pthread->master, zserv_flush_data, client,
-				 client->sock, &client->t_write);
+		zserv_client_event(client, ZSERV_CLIENT_FLUSH_DATA);
 		break;
 	case BUFFER_EMPTY:
 		break;
@@ -188,11 +235,10 @@ static int zserv_write(struct thread *thread)
 			  client->sock);
 		zlog_warn("%s: closing connection to %s", __func__,
 			  zebra_route_string(client->proto));
-		zebra_client_close(client);
+		zserv_client_close(client);
 		return -1;
 	case BUFFER_PENDING:
-		thread_add_write(client->pthread->master, zserv_flush_data,
-				 client, client->sock, &client->t_write);
+		zserv_client_event(client, ZSERV_CLIENT_FLUSH_DATA);
 		break;
 	case BUFFER_EMPTY:
 		break;
@@ -201,7 +247,7 @@ static int zserv_write(struct thread *thread)
 	pthread_mutex_lock(&client->obuf_mtx);
 	{
 		if (client->obuf_fifo->count)
-			zebra_event(client, ZEBRA_WRITE);
+			zserv_client_event(client, ZSERV_CLIENT_WRITE);
 	}
 	pthread_mutex_unlock(&client->obuf_mtx);
 
@@ -231,7 +277,6 @@ static void zserv_write_incoming(struct stream *orig, uint16_t command)
 }
 #endif
 
-
 /*
  * Read and process data from a client socket.
  *
@@ -381,36 +426,39 @@ static int zserv_read(struct thread *thread)
 			   zebrad.packets_to_process - p2p);
 
 	/* Schedule job to process those packets */
-	thread_add_event(zebrad.master, zserv_process_messages, client, 0,
-			 NULL);
+	zserv_event(client, ZSERV_PROCESS_MESSAGES);
 
 	/* Reschedule ourselves */
-	zebra_event(client, ZEBRA_READ);
+	zserv_client_event(client, ZSERV_CLIENT_READ);
 
 	return 0;
 
 zread_fail:
-	zebra_client_close(client);
+	zserv_client_close(client);
 	return -1;
 }
 
-static void zebra_event(struct zserv *client, enum event event)
+static void zserv_client_event(struct zserv *client,
+			       enum zserv_client_event event)
 {
 	switch (event) {
-	case ZEBRA_READ:
+	case ZSERV_CLIENT_READ:
 		thread_add_read(client->pthread->master, zserv_read, client,
 				client->sock, &client->t_read);
 		break;
-	case ZEBRA_WRITE:
+	case ZSERV_CLIENT_WRITE:
 		thread_add_write(client->pthread->master, zserv_write, client,
 				 client->sock, &client->t_write);
 		break;
+	case ZSERV_CLIENT_FLUSH_DATA:
+		thread_add_write(client->pthread->master, zserv_flush_data,
+				 client, client->sock, &client->t_write);
+		break;
 	}
 }
 
 /* Main thread lifecycle ---------------------------------------------------- */
 
-
 /*
  * Read and process messages from a client.
  *
@@ -472,20 +520,19 @@ static int zserv_process_messages(struct thread *thread)
 	pthread_mutex_lock(&client->ibuf_mtx);
 	{
 		if (client->ibuf_fifo->count)
-			thread_add_event(zebrad.master, zserv_process_messages,
-					 client, 0, NULL);
+			zserv_event(client, ZSERV_PROCESS_MESSAGES);
 	}
 	pthread_mutex_unlock(&client->ibuf_mtx);
 
 	return 0;
 }
 
-int zebra_server_send_message(struct zserv *client, struct stream *msg)
+int zserv_send_message(struct zserv *client, struct stream *msg)
 {
 	pthread_mutex_lock(&client->obuf_mtx);
 	{
 		stream_fifo_push(client->obuf_fifo, msg);
-		zebra_event(client, ZEBRA_WRITE);
+		zserv_client_event(client, ZSERV_CLIENT_WRITE);
 	}
 	pthread_mutex_unlock(&client->obuf_mtx);
 	return 0;
@@ -493,8 +540,8 @@ int zebra_server_send_message(struct zserv *client, struct stream *msg)
 
 
 /* Hooks for client connect / disconnect */
-DEFINE_HOOK(zapi_client_connect, (struct zserv *client), (client));
-DEFINE_KOOH(zapi_client_close, (struct zserv *client), (client));
+DEFINE_HOOK(zserv_client_connect, (struct zserv *client), (client));
+DEFINE_KOOH(zserv_client_close, (struct zserv *client), (client));
 
 /*
  * Deinitialize zebra client.
@@ -508,9 +555,9 @@ DEFINE_KOOH(zapi_client_close, (struct zserv *client), (client));
  * managed by the owning pthread and any tasks associated with them must have
  * been stopped prior to invoking this function.
  */
-static void zebra_client_free(struct zserv *client)
+static void zserv_client_free(struct zserv *client)
 {
-	hook_call(zapi_client_close, client);
+	hook_call(zserv_client_close, client);
 
 	/* Close file descriptor. */
 	if (client->sock) {
@@ -562,7 +609,7 @@ static void zebra_client_free(struct zserv *client)
  * terminate the client thread, update relevant internal datastructures and
  * free any resources allocated by the main thread.
  */
-static int zebra_client_handle_close(struct thread *thread)
+static int zserv_handle_client_close(struct thread *thread)
 {
 	struct zserv *client = THREAD_ARG(thread);
 
@@ -582,7 +629,7 @@ static int zebra_client_handle_close(struct thread *thread)
 	client->pthread = NULL;
 
 	listnode_delete(zebrad.client_list, client);
-	zebra_client_free(client);
+	zserv_client_free(client);
 	return 0;
 }
 
@@ -596,7 +643,7 @@ static int zebra_client_handle_close(struct thread *thread)
  * sock
  *    client's socket file descriptor
  */
-static void zebra_client_create(int sock)
+static void zserv_client_create(int sock)
 {
 	struct zserv *client;
 	int i;
@@ -645,17 +692,19 @@ static void zebra_client_create(int sock)
 	zebra_vrf_update_all(client);
 
 	/* start read loop */
-	zebra_event(client, ZEBRA_READ);
+	zserv_client_event(client, ZSERV_CLIENT_READ);
 
 	/* call callbacks */
-	hook_call(zapi_client_connect, client);
+	hook_call(zserv_client_connect, client);
 
 	/* start pthread */
 	frr_pthread_run(client->pthread, NULL);
 }
 
-/* Accept code of zebra server socket. */
-static int zebra_accept(struct thread *thread)
+/*
+ * Accept socket connection.
+ */
+static int zserv_accept(struct thread *thread)
 {
 	int accept_sock;
 	int client_sock;
@@ -665,7 +714,7 @@ static int zebra_accept(struct thread *thread)
 	accept_sock = THREAD_FD(thread);
 
 	/* Reregister myself. */
-	thread_add_read(zebrad.master, zebra_accept, NULL, accept_sock, NULL);
+	zserv_event(NULL, ZSERV_ACCEPT);
 
 	len = sizeof(struct sockaddr_in);
 	client_sock = accept(accept_sock, (struct sockaddr *)&client, &len);
@@ -680,16 +729,14 @@ static int zebra_accept(struct thread *thread)
 	set_nonblocking(client_sock);
 
 	/* Create new zebra client. */
-	zebra_client_create(client_sock);
+	zserv_client_create(client_sock);
 
 	return 0;
 }
 
-/* Make zebra server socket, wiping any existing one (see bug #403). */
-void zebra_zserv_socket_init(char *path)
+void zserv_start(char *path)
 {
 	int ret;
-	int sock;
 	mode_t old_mask;
 	struct sockaddr_storage sa;
 	socklen_t sa_len;
@@ -702,8 +749,8 @@ void zebra_zserv_socket_init(char *path)
 	old_mask = umask(0077);
 
 	/* Make UNIX domain socket. */
-	sock = socket(sa.ss_family, SOCK_STREAM, 0);
-	if (sock < 0) {
+	zebrad.sock = socket(sa.ss_family, SOCK_STREAM, 0);
+	if (zebrad.sock < 0) {
 		zlog_warn("Can't create zserv socket: %s",
 			  safe_strerror(errno));
 		zlog_warn(
@@ -712,8 +759,8 @@ void zebra_zserv_socket_init(char *path)
 	}
 
 	if (sa.ss_family != AF_UNIX) {
-		sockopt_reuseaddr(sock);
-		sockopt_reuseport(sock);
+		sockopt_reuseaddr(zebrad.sock);
+		sockopt_reuseport(zebrad.sock);
 	} else {
 		struct sockaddr_un *suna = (struct sockaddr_un *)&sa;
 		if (suna->sun_path[0])
@@ -721,40 +768,60 @@ void zebra_zserv_socket_init(char *path)
 	}
 
 	zserv_privs.change(ZPRIVS_RAISE);
-	setsockopt_so_recvbuf(sock, 1048576);
-	setsockopt_so_sendbuf(sock, 1048576);
+	setsockopt_so_recvbuf(zebrad.sock, 1048576);
+	setsockopt_so_sendbuf(zebrad.sock, 1048576);
 	zserv_privs.change(ZPRIVS_LOWER);
 
 	if (sa.ss_family != AF_UNIX && zserv_privs.change(ZPRIVS_RAISE))
 		zlog_err("Can't raise privileges");
 
-	ret = bind(sock, (struct sockaddr *)&sa, sa_len);
+	ret = bind(zebrad.sock, (struct sockaddr *)&sa, sa_len);
 	if (ret < 0) {
 		zlog_warn("Can't bind zserv socket on %s: %s", path,
 			  safe_strerror(errno));
 		zlog_warn(
 			"zebra can't provide full functionality due to above error");
-		close(sock);
+		close(zebrad.sock);
+		zebrad.sock = -1;
 		return;
 	}
 	if (sa.ss_family != AF_UNIX && zserv_privs.change(ZPRIVS_LOWER))
 		zlog_err("Can't lower privileges");
 
-	ret = listen(sock, 5);
+	ret = listen(zebrad.sock, 5);
 	if (ret < 0) {
 		zlog_warn("Can't listen to zserv socket %s: %s", path,
 			  safe_strerror(errno));
 		zlog_warn(
 			"zebra can't provide full functionality due to above error");
-		close(sock);
+		close(zebrad.sock);
+		zebrad.sock = -1;
 		return;
 	}
 
 	umask(old_mask);
 
-	thread_add_read(zebrad.master, zebra_accept, NULL, sock, NULL);
+	zserv_event(NULL, ZSERV_ACCEPT);
 }
 
+void zserv_event(struct zserv *client, enum zserv_event event)
+{
+	switch (event) {
+	case ZSERV_ACCEPT:
+		thread_add_read(zebrad.master, zserv_accept, NULL, zebrad.sock,
+				NULL);
+		break;
+	case ZSERV_PROCESS_MESSAGES:
+		thread_add_event(zebrad.master, zserv_process_messages, client,
+				 0, NULL);
+		break;
+	case ZSERV_HANDLE_CLOSE:
+		thread_add_event(zebrad.master, zserv_handle_client_close,
+				 client, 0, NULL);
+	}
+}
+
+
 /* General purpose ---------------------------------------------------------- */
 
 #define ZEBRA_TIME_BUF 32
@@ -895,7 +962,7 @@ static void zebra_show_client_brief(struct vty *vty, struct zserv *client)
 		client->v6_route_del_cnt);
 }
 
-struct zserv *zebra_find_client(uint8_t proto, unsigned short instance)
+struct zserv *zserv_find_client(uint8_t proto, unsigned short instance)
 {
 	struct listnode *node, *nnode;
 	struct zserv *client;
@@ -973,7 +1040,10 @@ void zserv_init(void)
 {
 	/* Client list init. */
 	zebrad.client_list = list_new();
-	zebrad.client_list->del = (void (*)(void *))zebra_client_free;
+	zebrad.client_list->del = (void (*)(void *)) zserv_client_free;
+
+	/* Misc init. */
+	zebrad.sock = -1;
 
 	install_element(ENABLE_NODE, &show_zebra_client_cmd);
 	install_element(ENABLE_NODE, &show_zebra_client_summary_cmd);
diff --git a/zebra/zserv.h b/zebra/zserv.h
index 77c5d9a89..6cd8b8c29 100644
--- a/zebra/zserv.h
+++ b/zebra/zserv.h
@@ -160,8 +160,8 @@ struct zserv {
 		struct zebra_vrf *zvrf
 
 /* Hooks for client connect / disconnect */
-DECLARE_HOOK(zapi_client_connect, (struct zserv *client), (client));
-DECLARE_KOOH(zapi_client_close, (struct zserv *client), (client));
+DECLARE_HOOK(zserv_client_connect, (struct zserv *client), (client));
+DECLARE_KOOH(zserv_client_close, (struct zserv *client), (client));
 
 /* Zebra instance */
 struct zebra_t {
@@ -169,6 +169,9 @@ struct zebra_t {
 	struct thread_master *master;
 	struct list *client_list;
 
+	/* Socket */
+	int sock;
+
 	/* default table */
 	uint32_t rtm_table_default;
 
@@ -186,12 +189,48 @@ struct zebra_t {
 extern struct zebra_t zebrad;
 extern unsigned int multipath_num;
 
-/* Prototypes. */
+/*
+ * Initialize Zebra API server.
+ *
+ * Installs CLI commands and creates the client list.
+ */
 extern void zserv_init(void);
-extern void zebra_zserv_socket_init(char *path);
-extern int zebra_server_send_message(struct zserv *client, struct stream *msg);
 
-extern struct zserv *zebra_find_client(uint8_t proto, unsigned short instance);
+/*
+ * Start Zebra API server.
+ *
+ * Allocates resources, creates the server socket and begins listening on the
+ * socket.
+ *
+ * path
+ *    where to place the Unix domain socket
+ */
+extern void zserv_start(char *path);
+
+/*
+ * Send a message to a connected Zebra API client.
+ *
+ * client
+ *    the client to send to
+ *
+ * msg
+ *    the message to send
+ */
+extern int zserv_send_message(struct zserv *client, struct stream *msg);
+
+/*
+ * Retrieve a client by its protocol and instance number.
+ *
+ * proto
+ *    protocol number
+ *
+ * instance
+ *    instance number
+ *
+ * Returns:
+ *    The Zebra API client.
+ */
+extern struct zserv *zserv_find_client(uint8_t proto, unsigned short instance);
 
 #if defined(HANDLE_ZAPI_FUZZING)
 extern void zserv_read_file(char *input);