bundles/wireguard: use one wireguard connection per peer instead of one for all

libs/s2s.py

@@ -0,0 +1,21 @@
+from ipaddress import IPv4Network
+
+AS_NUMBERS = {
+    #               4290xxxxxx
+    'home':         4290000138,
+    'htz-cloud':    4290000137,
+    'ovh':          4290000001,
+}
+
+def get_subnet_for_connection(repo, peer_a, peer_b):
+    # XXX this assumes there are never more than 128 nodes which match that expression
+    nodes = sorted({node.name for node in repo.nodes if node.has_bundle('wireguard')})
+
+    assert peer_a in nodes
+    assert peer_b in nodes
+
+    pos_peer_a = nodes.index(peer_a)
+    pos_peer_b = nodes.index(peer_b)
+
+    vpn_subnet = list(IPv4Network('169.254.0.0/16').subnets(new_prefix=24))[pos_peer_a]
+    return list(IPv4Network(vpn_subnet).subnets(new_prefix=31))[pos_peer_b]