From 55618406752e0e62c098ade7aee7947b2c8553b9 Mon Sep 17 00:00:00 2001
From: Renato Westphal <renato@opensourcerouting.org>
Date: Thu, 22 Feb 2024 14:54:07 -0300
Subject: [PATCH] bgp: handle well-known communities during the route
 dissemination phase

For now, NO_EXPORT and NO_EXPORT_SUBCONFED are treated the same
since RFC 3065 isn't supported yet ("Autonomous System Confederations
for BGP").

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>
---
 holo-bgp/src/events.rs           | 24 +++++++++++++++++++++++-
 holo-bgp/src/packet/attribute.rs |  4 ++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/holo-bgp/src/events.rs b/holo-bgp/src/events.rs
index 176f8cd0..ab8d1bb8 100644
--- a/holo-bgp/src/events.rs
+++ b/holo-bgp/src/events.rs
@@ -9,7 +9,7 @@ use std::net::IpAddr;
 
 use chrono::Utc;
 use holo_protocol::InstanceShared;
-use holo_utils::bgp::RouteType;
+use holo_utils::bgp::{RouteType, WellKnownCommunities};
 use holo_utils::ip::{IpAddrKind, IpNetworkKind};
 use holo_utils::policy::{PolicyResult, PolicyType};
 use holo_utils::socket::{TcpConnInfo, TcpStream};
@@ -728,6 +728,28 @@ pub(crate) fn advertise_routes<A>(
             return false;
         }
 
+        // Handle well-known communities.
+        if let Some(comm) = &route.attrs.comm {
+            for comm in comm
+                .value
+                .iter()
+                .filter_map(|comm| WellKnownCommunities::from_u32(comm.0))
+            {
+                // Do not advertise to any other peer.
+                if comm == WellKnownCommunities::NoAdvertise {
+                    return false;
+                }
+
+                // Do not advertise to external peers.
+                if nbr.peer_type == PeerType::External
+                    && (comm == WellKnownCommunities::NoExport
+                        || comm == WellKnownCommunities::NoExportSubconfed)
+                {
+                    return false;
+                }
+            }
+        }
+
         true
     });
 
diff --git a/holo-bgp/src/packet/attribute.rs b/holo-bgp/src/packet/attribute.rs
index aa9c99bd..e901a758 100644
--- a/holo-bgp/src/packet/attribute.rs
+++ b/holo-bgp/src/packet/attribute.rs
@@ -1400,6 +1400,10 @@ impl<T: CommType> CommList<T> {
     fn length(&self) -> u16 {
         ATTR_MIN_LEN_EXT + (self.0.len() * T::LENGTH) as u16
     }
+
+    pub(crate) fn iter(&self) -> impl Iterator<Item = &T> {
+        self.0.iter()
+    }
 }
 
 // ===== helper functions =====