From fae628f0b2654c2998d20d3e2a882ef6205471f4 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <hg@lukegb.com>
Date: Thu, 28 Mar 2024 00:45:06 +0000
Subject: [PATCH] rexxar: set a kt_prefsrc

---
 ops/nixos/lib/bgp.nix    | 12 ++++++++++--
 ops/nixos/rexxar/bgp.nix |  2 ++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/ops/nixos/lib/bgp.nix b/ops/nixos/lib/bgp.nix
index 880a46e575..d4653b1813 100644
--- a/ops/nixos/lib/bgp.nix
+++ b/ops/nixos/lib/bgp.nix
@@ -15,7 +15,6 @@ let
       if ! (avoid_martians4()) then reject;
       ${if ix.remote.must_be_next_hop then "if (bgp_path.first != ${toString ix.remote.asn}) then reject;" else "# no next-hop requirement"}
       ${lib.concatMapStringsSep "\n" (asn: "if (bgp_path ~ [= * ${toString asn} * =]) then reject;") ix.remote.drop_asns}
-      if (bgp_path ~ [= * 16276 * =] && gw = 195.66.225.6) then gw = 195.66.224.220;  # OVH must go via router 1; router 2 is bork.
       ${lib.optionalString (ixName == "quadv") ''
         bgp_ext_community.add((ro, 205479, 1000));
         bgp_ext_community.add((ro, 205479, 4000));  # etheroute
@@ -26,6 +25,7 @@ let
         bgp_community.add((64600, 3356));  # no Lumen
         bgp_community.add((64600, 5459));  # no LINX peers (inc. RS)
       ''}
+      ${if ix.remote.pref_src.v4 != null then "krt_prefsrc = ${ix.remote.pref_src.v4};" else "# no krt_prefsrc"}
       bgp_local_pref = ${toString ix.remote.bgp_local_pref};
       accept;
     }
@@ -52,7 +52,7 @@ let
       if ! (avoid_martians6()) then reject;
       ${if ix.remote.must_be_next_hop then "if (bgp_path.first != ${toString ix.remote.asn}) then reject;" else "# no next-hop requirement"}
       ${lib.concatMapStringsSep "\n" (asn: "if (bgp_path ~ [= * ${toString asn} * =]) then reject;") ix.remote.drop_asns}
-      if (bgp_path ~ [= * 16276 * =] && gw = 2001:7f8:4::3f94:2) then gw = 2001:7f8:4::3f94:1;  # OVH must go via router 1; router 2 is bork.
+      ${if ix.remote.pref_src.v6 != null then "krt_prefsrc = ${ix.remote.pref_src.v6};" else "# no krt_prefsrc"}
       bgp_local_pref = ${toString ix.remote.bgp_local_pref};
       accept;
     }
@@ -189,6 +189,14 @@ in {
                         type = nullOr int;
                         default = null;
                       };
+                      pref_src.v4 = mkOption { # lukegbgp.config.peering.<foo>.pref_src.v4
+                        type = nullOr str;
+                        default = null;
+                      };
+                      pref_src.v6 = mkOption { # lukegbgp.config.peering.<foo>.pref_src.v6
+                        type = nullOr str;
+                        default = null;
+                      };
                       must_be_next_hop = mkOption { # lukegbgp.config.peering.<foo>.remote.must_be_next_hop
                         type = bool;
                         default = true;
diff --git a/ops/nixos/rexxar/bgp.nix b/ops/nixos/rexxar/bgp.nix
index 2806940bb0..fa5177427e 100644
--- a/ops/nixos/rexxar/bgp.nix
+++ b/ops/nixos/rexxar/bgp.nix
@@ -34,6 +34,8 @@
         link.linx = base ++ [{
           local.v4 = "195.66.224.58";
           local.v6 = "2001:7f8:4::3:22a7:1";
+          remote.pref_src.v4 = "195.74.55.21";
+          remote.pref_src.v6 = "2a03:ee40:8080:9:1::2";
         }];
         peer.velox.remote = {
           asn = 3170;