bgpd, lib: Indicate when we are buffering instead of immediately sending down ZAPI

When FRR sends data over the ZAPI protocol from the upper levels to zebra, indicate
to the calling functions that we have started buffering data to be sent if the
socket is full underneath it.

Also add a call back function `zebra_buffer_write_ready` that we can call
when an upper level protocol's socket buffer has been drained.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>

1 files changed, 34 insertions, 17 deletions

diff --git a/lib/zclient.h b/lib/zclient.h
index d9237048bd..e8629acbee 100644
--- a/lib/zclient.h
+++ b/lib/zclient.h
@@ -321,6 +321,18 @@ struct zclient {
 	/* Pointer to the callback functions. */
 	void (*zebra_connected)(struct zclient *);
 	void (*zebra_capabilities)(struct zclient_capabilities *cap);
+
+	/*
+	 * When the zclient attempts to write the stream data to
+	 * it's named pipe to/from zebra, we may have a situation
+	 * where the other daemon has not fully drained the data
+	 * from the socket.  In this case provide a mechanism
+	 * where we will *still* buffer the data to be sent
+	 * and also provide a callback mechanism to the appropriate
+	 * place where we can signal that we're ready to receive
+	 * more data.
+	 */
+	void (*zebra_buffer_write_ready)(void);
 	int (*router_id_update)(ZAPI_CALLBACK_ARGS);
 	int (*interface_address_add)(ZAPI_CALLBACK_ARGS);
 	int (*interface_address_delete)(ZAPI_CALLBACK_ARGS);
@@ -754,9 +766,9 @@ extern void redist_del_all_instances(struct redist_proto *red);
  * we have installed and play some special games
  * to get them both installed.
  */
-extern void zclient_send_vrf_label(struct zclient *zclient, vrf_id_t vrf_id,
-				   afi_t afi, mpls_label_t label,
-				   enum lsp_types_t ltype);
+extern int zclient_send_vrf_label(struct zclient *zclient, vrf_id_t vrf_id,
+				  afi_t afi, mpls_label_t label,
+				  enum lsp_types_t ltype);
 
 extern void zclient_send_reg_requests(struct zclient *, vrf_id_t);
 extern void zclient_send_dereg_requests(struct zclient *, vrf_id_t);
@@ -764,10 +776,10 @@ extern int zclient_send_router_id_update(struct zclient *zclient,
 					 zebra_message_types_t type, afi_t afi,
 					 vrf_id_t vrf_id);
 
-extern void zclient_send_interface_radv_req(struct zclient *zclient,
-					    vrf_id_t vrf_id,
-					    struct interface *ifp, int enable,
-					    int ra_interval);
+extern int zclient_send_interface_radv_req(struct zclient *zclient,
+					   vrf_id_t vrf_id,
+					   struct interface *ifp, int enable,
+					   int ra_interval);
 extern int zclient_send_interface_protodown(struct zclient *zclient,
 					    vrf_id_t vrf_id,
 					    struct interface *ifp, bool down);
@@ -792,8 +804,13 @@ extern void zclient_redistribute(int command, struct zclient *, afi_t, int type,
 extern void zclient_redistribute_default(int command, struct zclient *,
 					 afi_t, vrf_id_t vrf_id);
 
-/* Send the message in zclient->obuf to the zebra daemon (or enqueue it).
-   Returns 0 for success or -1 on an I/O error. */
+/*
+ * Send the message in zclient->obuf to the zebra daemon (or enqueue it).
+ * Returns:
+ * -1 on a I/O error
+ *  0 data was successfully sent
+ *  1 data was buffered for future usage
+ */
 extern int zclient_send_message(struct zclient *);
 
 /* create header for command, length to be filled in by user later */
@@ -851,9 +868,9 @@ extern int zclient_read_header(struct stream *s, int sock, uint16_t *size,
  */
 extern bool zapi_parse_header(struct stream *zmsg, struct zmsghdr *hdr);
 
-extern void zclient_interface_set_master(struct zclient *client,
-					 struct interface *master,
-					 struct interface *slave);
+extern int zclient_interface_set_master(struct zclient *client,
+					struct interface *master,
+					struct interface *slave);
 extern struct interface *zebra_interface_state_read(struct stream *s, vrf_id_t);
 extern struct connected *zebra_interface_address_read(int, struct stream *,
 						      vrf_id_t);
@@ -970,12 +987,12 @@ static inline void zapi_route_set_blackhole(struct zapi_route *api,
 	SET_FLAG(api->message, ZAPI_MESSAGE_NEXTHOP);
 };
 
-extern void zclient_send_mlag_register(struct zclient *client,
-				       uint32_t bit_map);
-extern void zclient_send_mlag_deregister(struct zclient *client);
+extern int zclient_send_mlag_register(struct zclient *client,
+				      uint32_t bit_map);
+extern int zclient_send_mlag_deregister(struct zclient *client);
 
-extern void zclient_send_mlag_data(struct zclient *client,
-				   struct stream *client_s);
+extern int zclient_send_mlag_data(struct zclient *client,
+				  struct stream *client_s);
 
 /*
  * Send an OPAQUE message, contents opaque to zebra - but note that