net-sim: skip files missing on the card; /api/write accepts a full path

Live-testing against a UICC without the EPS files (no USIM service 85)
and without the Kc files showed the runner aborting when EPSLOCI/Kc were
absent.  write_binary/write_record now take an 'optional' flag: a missing
candidate file is logged as a skip step instead of failing the scenario
(store_epsnsc, real/dummy locations, churn and Kc writes).  Also allow
POST /api/write to select by 'path' like /api/select and /api/read (the
netsim live test needed it to restore the captured file values).

docs/api.md

@@ -350,6 +350,13 @@ Write raw hex data to a file.
 {"name": "EF.ICCID", "fid": "2FE2", "data": "A0A1A2...", "parent_path": ["MF"]}
 ```
 
+A full path may be used instead of name/fid/parent, like `/api/select` and
+`/api/read`:
+
+```json
+{"path": "ADF.USIM/6F7E", "data": "4FE69DE7..."}
+```
+
 For record files:
 ```json
 {"name": "EF.ADN", "fid": "6F3A", "data": "A0A1...", "record_nr": 1, "parent_path": ["MF", "7F10"]}

pysim_simple_server/netsim.py

@@ -405,8 +405,14 @@ class NetSimRunner:
             raise StepError('%s returned SW %s' % (kw.get('action'), sw))
         return step
 
-    def write_binary(self, key, data_hex, pad=True, label=None):
+    def write_binary(self, key, data_hex, pad=True, label=None, optional=False):
+        try:
             path = self._open(key)
+        except StepError as e:
+            if optional:
+                self._add('skip', file=label or key, note=str(e))
+                return None
+            raise
         size = self.lchan.selected_file_size()
         data = data_hex
         if pad and size:
@@ -415,8 +421,14 @@ class NetSimRunner:
         return self._check(data, sw, action='update_binary', file=label or key,
                            path=path)
 
-    def write_record(self, key, data_hex, record=1, pad=True, label=None):
+    def write_record(self, key, data_hex, record=1, pad=True, label=None, optional=False):
+        try:
             path = self._open(key)
+        except StepError as e:
+            if optional:
+                self._add('skip', file=label or key, note=str(e))
+                return None
+            raise
         size = self.lchan.selected_file_record_len()
         data = data_hex
         if pad and size:
@@ -473,29 +485,33 @@ class NetSimRunner:
             self.kasme,
             _hexint(self.p('ul', 0)), _hexint(self.p('dl', 0)),
             _hexint(self.p('algo', '02'), 0x02)),
-            label='epsnsc')
+            label='epsnsc', optional=True)
 
     def write_real_locations(self, status=ST_UPDATED):
         self.write_binary('loci', build_loci(
             self.p('tmsi') or rand_hex(4), self.plmn, self.lac, status),
-            label='loci')
+            label='loci', optional=True)
         self.write_binary('psloci', build_psloci(
             self.p('ptmsi') or rand_hex(4), self.p('ptmsi_sig') or rand_hex(3),
-            self.plmn, self.lac, self.rac, status), label='psloci')
+            self.plmn, self.lac, self.rac, status), label='psloci', optional=True)
         self.write_binary('epsloci', build_epsloci(
             self.p('guti') or rand_hex(12), self.plmn, self.tac, status),
-            label='epsloci')
+            label='epsloci', optional=True)
 
     def write_dummy_locations(self, status=ST_NOT_UPDATED):
-        self.write_binary('loci', build_loci_dummy(self.plmn), label='loci')
+        self.write_binary('loci', build_loci_dummy(self.plmn), label='loci',
-        self.write_binary('psloci', build_psloci_dummy(self.plmn), label='psloci')
+                          optional=True)
-        self.write_binary('epsloci', build_epsloci_dummy(self.plmn), label='epsloci')
+        self.write_binary('psloci', build_psloci_dummy(self.plmn), label='psloci',
+                          optional=True)
+        self.write_binary('epsloci', build_epsloci_dummy(self.plmn),
+                          label='epsloci', optional=True)
 
     def invalidate_kc(self):
         for key in ('kc', 'kcgprs'):
             try:
                 self._open(key)
-            except StepError:
+            except StepError as e:
+                self._add('skip', file=key, note=str(e))
                 continue
             size = self.lchan.selected_file_size() or 9
             self.write_binary(key, build_kc_invalidate(size), pad=False,
@@ -507,7 +523,8 @@ class NetSimRunner:
         for key in ('kc', 'kcgprs'):
             try:
                 self._open(key)
-            except StepError:
+            except StepError as e:
+                self._add('skip', file=key, note=str(e))
                 continue
             size = self.lchan.selected_file_size() or 9
             self.write_binary(key, build_kc(kc, algo, size), pad=False,
@@ -569,7 +586,11 @@ class NetSimRunner:
             self.kasme,
             _hexint(self.p('ul', 0)), _hexint(self.p('dl', 0)),
             _hexint(self.p('algo', '02'), 0x02))
+        try:
             self._open('epsnsc')
+        except StepError as e:
+            self._add('skip', file='epsnsc', note=str(e))
+            return
         size = self.lchan.selected_file_record_len() or 54
         invalid = build_epsnsc_invalidate(size, self.kasme)
         for _i in range(max(1, count)):

pysim_simple_server/server.py

@@ -3706,6 +3706,7 @@ class PysimHandler(BaseHTTPRequestHandler):
             parent_sel = body.get('parent_sel')
             parent_path = body.get('parent_path')
             allow_probe = bool(body.get('allow_probe'))
+            path = body.get('path')
             rs = app.rs
             if not rs:
                 self._send_json({'error': _err('no_card_state', lang)}, 503)
@@ -3714,6 +3715,9 @@ class PysimHandler(BaseHTTPRequestHandler):
             lchan = rs.lchan[0]
             cleanup = None
             try:
+                if path:
+                    _, cleanup = _select_path(lchan, path, app)
+                else:
                     sel = fid if fid else name
                     _, cleanup = _select_with_parent(lchan, sel, parent_sel, app, parent_path, allow_probe)
                 ft = _get_file_type(lchan, lchan.selected_file)

tests/test_netsim.py

@@ -310,6 +310,24 @@ class RunnerTests(unittest.TestCase):
         with self.assertRaises(ValueError):
             runner.run('nope')
 
+    def test_missing_files_are_skipped_not_fatal(self):
+        # A card without the EPS files / Kc (e.g. no USIM service 85): the
+        # scenario must still succeed, writing what exists and noting skips.
+        files = {'6F7E': FakeFileInfo(size=11), '6F73': FakeFileInfo(size=14),
+                 '6F43': FakeFileInfo(size=2, data='27FF')}
+        lchan = FakeLchan(files)
+        app = SimpleNamespace(rs=SimpleNamespace(lchan=[lchan]))
+        srv = FakeSrv()
+        runner = netsim.NetSimRunner(srv, app, event_list=[3], sleep=lambda s: None)
+        out = runner.run('service_lost')
+        self.assertTrue(out['success'])
+        skipped = {s['file'] for s in out['steps'] if s['action'] == 'skip'}
+        for key in ('epsnsc', 'epsloci', 'kc', 'kcgprs'):
+            self.assertIn(key, skipped)
+        written = [w[1] for w in lchan.writes]
+        self.assertIn('6F7E', written)
+        self.assertIn('6F73', written)
+
 
 if __name__ == '__main__':
     unittest.main()