Add minimal SIG topology entry support (#374)

Previously we've had even more minimal support for SIG topology entries
only in User ASes.
Add support for an explicit SIG Service object, to allow configuring the
same thing in the SCIONLab infrastructure ASes.
As before, this is only concerned with adding a topology entry so that
the routers are able to resolve the SIG service address -- actually
configuring the SIG itself is still out of scope and is done manually on
each host.

Author: matzf

scionlab/fixtures/testdata.yaml

@@ -3640,7 +3640,7 @@
     ssh_host: 172.31.0.110
     uid: 9b2eedd0a1bd41d59a6c3a37a0317024
     secret: e563ae76441a44b3b225cb26e569dc72
-    config_version: 9
+    config_version: 10
     config_version_deployed: 0
     config_queried_at: null
 - model: scionlab.host
@@ -4772,6 +4772,12 @@
     AS: 20
     host: 20
     type: CS
+- model: scionlab.service
+  pk: 23
+  fields:
+    AS: 5
+    host: 5
+    type: SIG
 - model: scionlab.vpn
   pk: 1
   fields:

scionlab/fixtures/testtopo.py

@@ -107,6 +107,7 @@ def makeLinkDef(type, as_id_tail_a, as_id_tail_b):
 extra_services = [
     (_expand_as_id(0x1107), Service.BW),
     (_expand_as_id(0x1406), Service.BW),
+    (_expand_as_id(0x1301), Service.SIG),
 ]
 
 # VPNs for APs, except 1303

scionlab/models/core.py

@@ -43,6 +43,7 @@
     BR_METRICS_PORT_BASE,
     CS_PORT,
     CS_METRICS_PORT,
+    SIG_CTRL_PORT,
     BW_PORT,
     PP_PORT,
     DEFAULT_HOST_INTERNAL_IP,
@@ -1071,10 +1072,12 @@ class Service(models.Model):
     and for any other service that communicates using SCION.
     """
     CS = 'CS'
+    SIG = 'SIG'
     BW = 'BW'
     PP = 'PP'
     SERVICE_TYPES = (
         (CS, 'Control Service'),  # monolithic control plane service
+        (SIG, 'SCION IP Gateway'),
         (BW, 'Bandwidth tester server'),
         (PP, 'Pingpong server'),
     )
@@ -1087,6 +1090,7 @@ class Service(models.Model):
     )
     SERVICE_PORTS = {
         CS: CS_PORT,
+        SIG: SIG_CTRL_PORT,
         BW: BW_PORT,
         PP: PP_PORT,
     }

scionlab/scion/topology.py

@@ -47,6 +47,14 @@ def _make_topo(self, with_sig_dummy_entry):
         self.routers = _fetch_routers(self.AS)
         self.services = _fetch_services(self.AS)
 
+        # add a dummy SIG entry (for user ASes).
+        if with_sig_dummy_entry and not any(s.type == Service.SIG for s in self.services):
+            sig = Service(AS=self.AS,
+                          host=self.AS.hosts.first(),
+                          type=Service.SIG)
+            sig.__dict__['instance_id'] = 1
+            self.services.append(sig)
+
         # AS wide entries
         self.topo = {}
         self.topo["isd_as"] = self.AS.isd_as_str()
@@ -55,9 +63,7 @@ def _make_topo(self, with_sig_dummy_entry):
 
         _topo_add_routers(self.topo, self.routers)
         _topo_add_control_services(self.topo, self.services)
-
-        if with_sig_dummy_entry:
-            _topo_add_sig_dummy_entry(self.topo, self.AS.hosts.first())
+        _topo_add_sigs(self.topo, self.services)
 
 
 def _fetch_routers(as_):
@@ -143,23 +149,23 @@ def _topo_add_control_services(topo_dict, services):
             ds_entry[instance_name] = service_instance_entry
 
 
-def _topo_add_sig_dummy_entry(topo_dict, host):
+def _topo_add_sigs(topo_dict, services):
     """
-    Add a "dummy" entry for the SIG in the topology.json, with localhost address and default
-    port.
+    Add SIG entries to the topology, with default ports.
     Note that we do not actually include any configuration for the SIG (out of scope).
     This is added to reduce the number of files that a scionlab user needs to modify when
     configuring the SIG.
     Note: this entry allows the border router to resolve SIG service address; this changes the
     error behaviour slighly when receiving packets addressed to the SIG without the SIG running.
     """
-    topo_dict["sigs"] = {
-        "sig-1": {  # id is irrelevant, not used for anything
-            "ctrl_addr": _join_host_port(host.internal_ip, SIG_CTRL_PORT),
-            "data_addr": _join_host_port(host.internal_ip, SIG_DATA_PORT),
-            # 'allow_interfaces': [...], unused for now, not setting anything
+    sigs = (s for s in services if s.type == Service.SIG)
+    for sig in sigs:
+        topo_dict["sigs"] = {
+            sig.instance_name: {
+                "ctrl_addr": _join_host_port(sig.host.internal_ip, SIG_CTRL_PORT),
+                "data_addr": _join_host_port(sig.host.internal_ip, SIG_DATA_PORT),
+            }
         }
-    }
 
 
 def _join_host_port(host, port):