Decode EVENT DOWNLOAD location/caller and CELL BROADCAST DOWNLOAD CB page

- EVENT DOWNLOAD: decode location information (PLMN/LAC/Cell), caller
  number (MT call Address), transaction identifier, subaddress
- CELL BROADCAST DOWNLOAD: decode CB page header (serial, message ID,
  DCS, page) with raw content hex
- frontend: render Caller/Transaction/Subaddress and CB page fields

Tests: 114.

frontend/index.html

@@ -537,9 +537,20 @@ function cmdRows(cmd) {
     if (cmd.events) rows.push(['Event', cmd.events.join(', ')]);
     if (cmd.location_status) rows.push(['Location status', cmd.location_status]);
     if (cmd.location_info) rows.push(['Location info', cmd.location_info]);
+    if (cmd.caller) rows.push(['Caller', cmd.caller]);
+    if (cmd.transaction_id !== undefined) rows.push(['Transaction', cmd.transaction_id]);
+    if (cmd.subaddress) rows.push(['Subaddress', cmd.subaddress]);
     if (cmd.smsc) rows.push(['SMSC', cmd.smsc]);
     if (cmd.tp_da) rows.push(['TP-DA', cmd.tp_da]);
     if (cmd.device_ids) rows.push(['Device IDs', cmd.device_ids]);
+    if (cmd.cb_page) {
+        const cb = cmd.cb_page;
+        if (cb.serial) rows.push(['CB serial', cb.serial]);
+        if (cb.message_id) rows.push(['CB message', cb.message_id]);
+        if (cb.dcs) rows.push(['CB DCS', cb.dcs]);
+        if (cb.page) rows.push(['CB page', cb.page]);
+        if (cb.content) rows.push(['CB content', cb.content]);
+    }
 
     // Proactive command fields (FETCH)
     if (cmd.title) rows.push(['Title', cmd.title]);

simtrace2_pysniff/server/decode.py

@@ -1152,6 +1152,32 @@ def _decode_ud(ud, udl, dcs, udhi, result):
     return result
 
 
+def _decode_cb_page(value):
+    """Decode a CELL BROADCAST DOWNLOAD CB page (TS 31.111 §8.5 / TS 23.041).
+
+    Layout: serial number (2), message identifier (2), DCS (1), page
+    parameter (1), content (up to 82 octets).  Content is returned as raw
+    hex (no text decode).
+    """
+    if len(value) < 6:
+        return {'content': value.hex().upper()}
+    serial = value[0:2].hex().upper()
+    message_id = value[2:4].hex().upper()
+    dcs = value[4]
+    page_byte = value[5]
+    total_pages = (page_byte >> 4) & 0x0F
+    page_num = page_byte & 0x0F
+    encoding, msg_class = _decode_dcs(dcs)
+    dcs_str = f'0x{dcs:02X} — {encoding}' + (f' (class {msg_class})' if msg_class else '')
+    return {
+        'serial': serial,
+        'message_id': '0x' + message_id,
+        'dcs': dcs_str,
+        'page': f'{page_num}/{total_pages}',
+        'content': value[6:].hex().upper(),
+    }
+
+
 def _decode_envelope(body):
     """Decode an ENVELOPE command body (TS 102 223 / TS 31.111)."""
     tlvs = parse_tlv(body)
@@ -1169,7 +1195,15 @@ def _decode_envelope(body):
                 if v:
                     result['location_status'] = LOCATION_STATUS.get(v[0], f'0x{v[0]:02X}')
             elif t == 0x13:  # Location information
-                result['location_info'] = v.hex().upper()
+                li = _decode_local_info(PLI_LOCATION_INFO, v)
+                result['location_info'] = li['value'] if li else v.hex().upper()
+            elif t in (0x06, 0x86):  # Address (caller's number, MT call)
+                result['caller'] = _decode_bcd_address(v)
+            elif t == 0x1C:  # Transaction identifier (MT call)
+                if v:
+                    result['transaction_id'] = v[0]
+            elif t in (0x08, 0x88):  # Subaddress
+                result['subaddress'] = v.hex().upper()
             elif t == 0x02:  # Device identities
                 result['device_ids'] = v.hex().upper()
     elif tag == 0xD5:  # MO SHORT MESSAGE CONTROL
@@ -1191,12 +1225,12 @@ def _decode_envelope(body):
                 result['tpdu'] = _decode_sm_tpdu(v)
             elif t == 0x02:
                 result['device_ids'] = v.hex().upper()
-    elif tag == 0xD2:  # CELL BROADCAST DOWNLOAD (structure only)
+    elif tag == 0xD2:  # CELL BROADCAST DOWNLOAD
         for t, _l, v in inner:
             if t == 0x02:
                 result['device_ids'] = v.hex().upper()
-            else:
+            elif t in (0x0C, 0x8C):  # CB page
-                result[f'tag_{t:02X}'] = v.hex().upper()
+                result['cb_page'] = _decode_cb_page(v)
     else:  # D3 / D4 / D7 — device identities only
         for t, _l, v in inner:
             if t == 0x02:

tests/test_decode.py

@@ -339,6 +339,36 @@ class TestEventDownload(unittest.TestCase):
         self.assertEqual(r['cmd']['events'], ['Location status'])
         self.assertEqual(r['cmd']['location_status'], 'No service')
 
+    def test_location_status_with_info(self):
+        r = decode_message(bytes.fromhex(
+            '80C2000017D615190103020282811B0100130952F02026ADBC51A16F9000'))
+        cmd = r['cmd']
+        self.assertEqual(cmd['location_status'], 'Normal service')
+        self.assertEqual(cmd['location_info'],
+                         'MCC 250 MNC 02 · LAC 0x26AD · Cell 0xBC51A16F')
+
+    def test_mt_call(self):
+        r = decode_message(bytes.fromhex(
+            '80C2000014D612190100020283811C010586069121436587099000'))
+        cmd = r['cmd']
+        self.assertEqual(cmd['events'], ['MT call'])
+        self.assertEqual(cmd['transaction_id'], 5)
+        self.assertEqual(cmd['caller'], '+1234567890')
+
+    def test_cell_broadcast(self):
+        cbp = ('4C511002F211' +
+               '040000313A0103035E047FFB0F31303238322A333036343835363234' +
+               '0D' * 54)
+        r = decode_message(bytes.fromhex(
+            '80C2000060D25E020283810C58' + cbp + '9000'))
+        cmd = r['cmd']
+        self.assertEqual(cmd['type'], 'CELL BROADCAST DOWNLOAD')
+        self.assertEqual(cmd['cb_page']['serial'], '4C51')
+        self.assertEqual(cmd['cb_page']['message_id'], '0x1002')
+        self.assertEqual(cmd['cb_page']['page'], '1/1')
+        self.assertEqual(cmd['cb_page']['content'],
+                         '040000313A0103035E047FFB0F31303238322A333036343835363234' + '0D' * 54)
+
 
 class TestSmTpdu(unittest.TestCase):
     def _bcd(self, number):