tshark: fix crash with -Tjson and -e field

Fix the assertion to check for the actual requirements. Add tests for -T
combined with -e.

Bug: 15444
Change-Id: I83e7663572db0c60194f6d6128b9e1ae7396b3f6
Fixes: v2.9.1rc0-226-g30c90fa745 ("epan: use json_dumper for json outputs.")
Reviewed-on: https://code.wireshark.org/review/31724
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

epan/print.c

@@ -390,7 +390,7 @@ write_ek_proto_tree(output_fields_t* fields,
             proto_tree_write_node_ek(edt->tree, &data);
         } else {
             /* Write out specified fields */
-            write_specified_fields(FORMAT_EK, fields, edt, cinfo, fh, data.dumper);
+            write_specified_fields(FORMAT_EK, fields, edt, cinfo, NULL, data.dumper);
         }
 
         json_dumper_end_object(&dumper);
@@ -2339,7 +2339,12 @@ static void write_specified_fields(fields_format format, output_fields_t *fields
     g_assert(fields);
     g_assert(fields->fields);
     g_assert(edt);
-    g_assert(fh);
+    /* JSON formats must go through json_dumper */
+    if (format == FORMAT_JSON || format == FORMAT_EK) {
+        g_assert(!fh && dumper);
+    } else {
+        g_assert(fh && !dumper);
+    }
 
     data.fields = fields;
     data.edt = edt;

test/suite_outputformats.py

@@ -14,41 +14,73 @@ import subprocesstest
 import fixtures
 from matchers import *
 
-@fixtures.fixture
-def check_outputformat(cmd_tshark, dirs, capture_file):
-    ''' Check a capture file against a sample, in json format. '''
-    def check_outputformat_real(self, pcap_file, format_option, format_file, multiline=False):
-        self.maxDiff = 1000000
-        tshark_proc = self.assertRun((cmd_tshark, '-r', capture_file(pcap_file), '-T', format_option,))
 
-        expected = open(os.path.join(dirs.baseline_dir, format_file)).read()
+@fixtures.fixture
+def check_outputformat(cmd_tshark, request, dirs, capture_file):
+    ''' Check a capture file against a sample, in json format. '''
+    def check_outputformat_real(format_option, pcap_file='dhcp.pcap',
+                                extra_args=[], expected=None, multiline=False):
+        self = request.instance
+        tshark_proc = self.assertRun([cmd_tshark, '-r', capture_file(pcap_file),
+                                      '-T', format_option] + extra_args)
+
+        # If a filename is given, load the expected values from those.
+        if isinstance(expected, str):
+            testdata = open(os.path.join(dirs.baseline_dir, expected)).read()
+            if multiline:
+                expected = [json.loads(line) for line in testdata.splitlines()]
+            else:
+                expected = json.loads(testdata)
         actual = tshark_proc.stdout_str
         if multiline:
-            expected = expected.splitlines()
             actual = actual.splitlines()
             self.assertEqual(len(expected), len(actual))
-            for line1, line2 in zip(expected, actual):
-                json.loads(line1)
-                json.loads(line2)
-                self.assertEqual(json.loads(line1), json.loads(line2))
+            for expectedObj, actualStr in zip(expected, actual):
+                self.assertEqual(expectedObj, json.loads(actualStr))
         else:
-            expected = json.loads(expected)
             actual = json.loads(actual)
             self.assertEqual(expected, actual)
 
     return check_outputformat_real
 
+
 @fixtures.mark_usefixtures('base_env')
 @fixtures.uses_fixtures
 class case_outputformats(subprocesstest.SubprocessTestCase):
+    maxDiff = 1000000
+
     def test_outputformat_json(self, check_outputformat):
         '''Decode some captures into json'''
-        check_outputformat(self, "dhcp.pcap", "json", "dhcp.json")
+        check_outputformat("json", expected="dhcp.json")
 
     def test_outputformat_jsonraw(self, check_outputformat):
         '''Decode some captures into jsonraw'''
-        check_outputformat(self, "dhcp.pcap", "jsonraw", "dhcp.jsonraw")
+        check_outputformat("jsonraw", expected="dhcp.jsonraw")
 
     def test_outputformat_ek(self, check_outputformat):
         '''Decode some captures into ek'''
-        check_outputformat(self, "dhcp.pcap", "ek", "dhcp.ek", True)
+        check_outputformat("ek", expected="dhcp.ek", multiline=True)
+
+    def test_outputformat_json_select_field(self, check_outputformat):
+        '''Checks that the -e option works with -Tjson.'''
+        check_outputformat("json", extra_args=['-eframe.number', '-c1'], expected=[
+            {
+                "_index": "packets-2004-12-05",
+                "_type": "pcap_file",
+                "_score": None,
+                "_source": {
+                    "layers": {
+                        "frame.number": [
+                            "1"
+                        ]
+                    }
+                }
+            }
+        ])
+
+    def test_outputformat_ek_select_field(self, check_outputformat):
+        '''Checks that the -e option works with -Tek.'''
+        check_outputformat("ek", extra_args=['-eframe.number', '-c1'], expected=[
+            {"index": {"_index": "packets-2004-12-05", "_type": "pcap_file"}},
+            {"timestamp": "1102274184317", "layers": {"frame_number": ["1"]}}
+        ], multiline=True)