From a1dd233e78d2675cd8fb49118023aa19578657c9 Mon Sep 17 00:00:00 2001
From: Quantum <quantum2048@gmail.com>
Date: Tue, 29 Oct 2024 01:26:32 -0400
Subject: [PATCH] Implement bird ASPA filters

---
 filter_aspa.conf | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 filter_aspa.conf

diff --git a/filter_aspa.conf b/filter_aspa.conf
new file mode 100644
index 0000000..38ac5fd
--- /dev/null
+++ b/filter_aspa.conf
@@ -0,0 +1,46 @@
+function is_aspa_invalid_customer() {
+    int prev_asn = MY_ASN;
+
+    for int cur_asn in bgp_path do {
+        if prev_asn != cur_asn && is_aspa_invalid_pair(prev_asn, cur_asn) then
+            return true;
+        prev_asn = cur_asn;
+    }
+
+    return false;
+}
+
+function is_aspa_invalid_peer(int peer_asn) {
+    int prev_asn = peer_asn;
+
+    for int cur_asn in bgp_path do {
+        if cur_asn != peer_asn && prev_asn != cur_asn &&
+                is_aspa_invalid_pair(prev_asn, cur_asn) then
+            return true;
+        prev_asn = cur_asn;
+    }
+
+    return false;
+}
+
+function is_aspa_invalid_upstream() {
+    int prev_asn = MY_ASN;
+    int max_up_ramp = bgp_path.len;
+    int min_down_ramp = 0;
+    int i = 0;
+
+    for int cur_asn in bgp_path do {
+        if prev_asn != cur_asn then {
+            if is_aspa_invalid_pair(cur_asn, cur_asn) && max_up_ramp > i then
+                max_up_ramp = i;
+
+            if is_aspa_invalid_pair(prev_asn, cur_asn) && min_down_ramp < i then
+                min_down_ramp = i;
+        }
+
+        prev_asn = cur_asn;
+        i = i + 1;
+    }
+
+    return min_down_ramp > max_up_ramp;
+}