Merge branch '271-aap2-link-duplicates' into 'master'

bundle_processor: Only send changes in FIB to agent

Closes #271

See merge request d3tn/ud3tn!243

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support for [RFC 9758](https://www.rfc-editor.org/rfc/rfc9758.html): implement the `ipn` 3-element format and LocalNode (`ipn:!.x`) EIDs
 - Custom source EIDs (including `dtn:none`) can be specified via AAP 2.0 and the corresponding tools (e.g. `aap2-send --source <eid>`), as long as the client provides the administrative (BDM) secret and requests BDM authorization
 - Add a compile-time flag `CLA_MTCP_ION_STCP_COMPATIBILITY` to make the MTCP CLA compatible with ION's STCP, which uses a different encoding for the length field. Note that this breaks compatibility with other implementations of the current MTCP draft specification.
+- Add a small Python tool (`aap2-fib-logger`) to show FIB changes propagated via AAP 2.0 (also as an example how to handle this)
 
 ### Removed
 
@@ -33,6 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - AAP 2.0 agents can now registered without an agent ID in case they do not wish to send/receive bundles (e.g. if they only do FIB control).
+- The full FIB is now only sent once to AAP 2.0 FIB subscribers, when they connect. Then, only changes are propagated.
 
 
 ## [v0.14.5] - 2025-09-26

components/ud3tn/bundle_processor.c

@@ -81,7 +81,7 @@ static inline void handle_signal(
 static void inform_link_status_change(
 	struct bp_context *const ctx,
 	const char *cla_addr,
-	enum fib_link_status);
+	enum fib_link_status status);
 static bool send_fib_to_agent(
 	void *context, const char *node_id,
 	const struct fib_entry *entry,
@@ -370,7 +370,7 @@ static inline void handle_signal(
 				&agent_feedback
 			);
 
-		if (aaps->agent.auth_fib)
+		if (aaps->agent.auth_fib && aaps->agent.is_subscriber)
 			fib_foreach(ctx->fib, send_fib_to_agent, ctx, NULL);
 		free(aaps);
 		break;
@@ -458,9 +458,24 @@ static void inform_link_status_change(
 		ctx,
 		cla_addr
 	);
-	if (status == FIB_LINK_STATUS_DOWN)
+	if (status == FIB_LINK_STATUS_DOWN) {
+		struct fib_link *const link = fib_lookup_cla_addr(ctx->fib, cla_addr);
+		const struct fib_entry entry = { .cla_addr = cla_addr };
+
+		// After Link deletion (by request), there is no node mapping anymore, but we need
+		// to report the CLA link being down anyway.
+		if (link && !link->reflist)
+			agent_send_fib_info(
+				ctx->agent_manager,
+				&entry,
+				NULL,
+				status,
+				ctx
+			);
+
 		// This MAY drop the Link, but only if the refcnt is zero.
 		fib_remove_link(ctx->fib, cla_addr);
+	}
 }
 
 void bundle_processor_execute_bdm_dispatch(
@@ -646,7 +661,8 @@ void bundle_processor_handle_fib_update_request(
 				)
 			);
 
-			// Treat as successful establishment to trigger agents.
+			// Always treat as successful establishment to trigger agents, as this will
+			// also notify agents other than the one that triggered the change.
 			if (lur == CLA_LINK_UPDATE_UNCHANGED ||
 			    lur == CLA_LINK_UPDATE_PERFORMED)
 				inform_link_status_change(
@@ -675,11 +691,24 @@ void bundle_processor_handle_fib_update_request(
 			);
 			// This will call fib_remove_link via
 			// BP_SIGNAL_LINK_DOWN.
-			cla_config->vtable->cla_end_scheduled_contact(
-				cla_config,
-				fib_request->node_id,
-				fib_request->cla_addr
+			const enum cla_link_update_result lur = (
+				cla_config->vtable->cla_end_scheduled_contact(
+					cla_config,
+					fib_request->node_id,
+					fib_request->cla_addr
+				)
 			);
+
+			// Note that we notify the agents even if there are no changes, as we do it
+			// with FIB_REQUEST_CREATE_LINK. This will also notify agents other than
+			// the one that triggered the change.
+			if (lur == CLA_LINK_UPDATE_UNCHANGED ||
+			    lur == CLA_LINK_UPDATE_PERFORMED)
+				inform_link_status_change(
+					ctx,
+					fib_request->cla_addr,
+					FIB_LINK_STATUS_DOWN
+				);
 		}
 
 		bool drop_assoc = true;

python-ud3tn-utils/pyproject.toml

@@ -31,6 +31,7 @@ aap2-bdm-static = "ud3tn_utils.aap2.bin.aap2_bdm_static:main"
 aap2-bdm-ud3tn-routing = "ud3tn_utils.aap2.bin.aap2_bdm_ud3tn_routing:main"
 aap2-config = "ud3tn_utils.aap2.bin.aap2_config:main"
 aap2-configure-link = "ud3tn_utils.aap2.bin.aap2_configure_link:main"
+aap2-fib-logger = "ud3tn_utils.aap2.bin.aap2_fib_logger:main"
 aap2-ping = "ud3tn_utils.aap2.bin.aap2_ping:main"
 aap2-receive = "ud3tn_utils.aap2.bin.aap2_receive:main"
 aap2-send = "ud3tn_utils.aap2.bin.aap2_send:main"

python-ud3tn-utils/ud3tn_utils/aap2/bin/aap2_fib_logger.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause OR Apache-2.0
+# encoding: utf-8
+
+"""Simple debug tool to log FIB updates issued by µD3TN."""
+
+import argparse
+import logging
+import sys
+
+from ud3tn_utils.aap2 import (
+    AAP2UnixClient,
+    AAP2TCPClient,
+    AAP2ServerDisconnected,
+    AuthType,
+    LinkStatus,
+    ResponseStatus,
+)
+from ud3tn_utils.aap2.bin.helpers import (
+    add_common_parser_arguments,
+    add_keepalive_parser_argument,
+    get_secret_from_args,
+    initialize_logger,
+)
+
+
+logger = logging.getLogger(__name__)
+
+
+def run_fib_logger(aap2_client):
+    logger.info("Waiting for FIB events...")
+
+    while True:
+        try:
+            msg = aap2_client.receive_msg()
+        except AAP2ServerDisconnected:
+            logger.warning("µD3TN has closed the connection.")
+            sys.exit(1)
+        except KeyboardInterrupt:
+            logger.info("Terminated by keyboard interrupt.")
+            sys.exit(130)  # exit status for SIGINT
+
+        if msg.WhichOneof("msg") == "link":
+            logger.warning(
+                "%s: %s%s",
+                {
+                    LinkStatus.LINK_STATUS_UNSPECIFIED: "CONNECTING",
+                    LinkStatus.LINK_STATUS_UP: "UP",
+                    LinkStatus.LINK_STATUS_DOWN: "DOWN",
+                }.get(msg.link.status, f"(status={msg.link.status})"),
+                (
+                    f"{msg.link.peer_node_id} via "
+                    if msg.link.peer_node_id else ""
+                ),
+                msg.link.peer_cla_addr,
+            )
+            aap2_client.send_response_status(
+                ResponseStatus.RESPONSE_STATUS_SUCCESS,
+            )
+        else:
+            if msg.WhichOneof("msg") != "keepalive":
+                logger.warning(
+                    "Received unhandled '%s' message discarding.",
+                    msg.WhichOneof("msg"),
+                )
+            # ACK the message in any case -- same response KA, unhandled
+            aap2_client.send_response_status(
+                ResponseStatus.RESPONSE_STATUS_ACK,
+            )
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="FIB update logger for µD3TN",
+    )
+    add_common_parser_arguments(parser)
+    add_keepalive_parser_argument(parser)
+    args = parser.parse_args()
+
+    global logger
+    logger = initialize_logger(args.verbosity)
+
+    if args.tcp:
+        aap2_client = AAP2TCPClient(address=args.tcp)
+    else:
+        aap2_client = AAP2UnixClient(address=args.socket)
+
+    with aap2_client:
+        secret = aap2_client.configure(
+            args.agentid,
+            subscribe=True,
+            secret=get_secret_from_args(args),
+            auth_type=AuthType.AUTH_TYPE_FIB_CONTROL,
+            keepalive_seconds=args.keepalive_seconds,
+        )
+        logger.info("AAP 2.0 agent configured as FIB subscriber!")
+        logger.debug("Assigned agent secret: '%s'", secret)
+        run_fib_logger(aap2_client)
+
+
+if __name__ == "__main__":
+    main()