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authorPeter Wu <peter@lekensteyn.nl>2018-11-20 02:47:36 +0100
committerAnders Broman <a.broman58@gmail.com>2018-11-20 05:03:56 +0000
commit656cc19fc7de25c3ac7f9d847c37745ccc272247 (patch)
tree79de668a68c25fd5bfe8ac2ee36d5b18824fa653
parentfb9c6905eff10f6f49a433ead8bd78e232fa068d (diff)
Replace JSON-GLib by custom JSON dumper library
The (optional) JSON-GLib library adds dependencies on GObject, GIO. For statically linked oss-fuzz builds it also adds libffi and more. To avoid these dependencies, replace JSON-GLib by some custom code. This allows `tshark -G elastic-mapping` to be enabled by default without extra deps. API design goals of the new JSON dumper library: - Small interface without a lot of abstraction. - Avoid memory allocations if possible (currently none, but maybe json_puts_string will be replaced to improve UTF-8 support). - Do not implement parsing, this is currently handled by jsmn. Methods to open/close array/objects and to set members are inspired by the JsonGlib interface. The interfaces to write values is inspired by the sharkd code (json_puts_string is also borrowed from that). The only observed differences in the tshark output: - JSON-GLib ignores duplicates, json_dumper does not and may produce duplicates and currently print two "ip.opt.sec_prot_auth_unassigned". - JSON-GLib adds a space before a colon (unimportant formatting detail). - (Not observed, but UTF-8 strings will be wrong like bug 14948.) A test was added to catch changes in the tshark output. I also fuzzed json_dumper with libFuzzer + UBSAN/ASAN and fixed an off-by-one error. Change-Id: I0c85b18777b04d1e0f613a3d59935ec59be87ff4 Link: https://www.wireshark.org/lists/wireshark-dev/201811/msg00052.html Reviewed-on: https://code.wireshark.org/review/30732 Petri-Dish: Peter Wu <peter@lekensteyn.nl> Tested-by: Petri Dish Buildbot Reviewed-by: Anders Broman <a.broman58@gmail.com>
-rw-r--r--debian/libwsutil0.symbols8
-rw-r--r--epan/proto.c140
-rw-r--r--epan/proto.h2
-rw-r--r--test/baseline/elastic-mapping-ip-subset.json45
-rw-r--r--test/suite_clopts.py17
-rw-r--r--tshark.c14
-rw-r--r--wsutil/CMakeLists.txt2
-rw-r--r--wsutil/json_dumper.c285
-rw-r--r--wsutil/json_dumper.h107
9 files changed, 525 insertions, 95 deletions
diff --git a/debian/libwsutil0.symbols b/debian/libwsutil0.symbols
index e5b9e771bc..791decb8fe 100644
--- a/debian/libwsutil0.symbols
+++ b/debian/libwsutil0.symbols
@@ -101,6 +101,14 @@ libwsutil.so.0 libwsutil0 #MINVER#
isprint_string@Base 1.10.0
isprint_utf8_string@Base 2.6.1
json_decode_string_inplace@Base 2.9.0
+ json_dumper_begin_array@Base 2.9.0
+ json_dumper_begin_object@Base 2.9.0
+ json_dumper_end_array@Base 2.9.0
+ json_dumper_end_object@Base 2.9.0
+ json_dumper_finish@Base 2.9.0
+ json_dumper_set_member_name@Base 2.9.0
+ json_dumper_value_anyf@Base 2.9.0
+ json_dumper_value_string@Base 2.9.0
json_parse@Base 2.9.0
json_validate@Base 2.9.0
linear2alaw@Base 1.12.0~rc1
diff --git a/epan/proto.c b/epan/proto.c
index c31f3d095e..9b73ab0bc7 100644
--- a/epan/proto.c
+++ b/epan/proto.c
@@ -20,6 +20,7 @@
#include <wsutil/bits_count_ones.h>
#include <wsutil/sign_ext.h>
#include <wsutil/utf8_entities.h>
+#include <wsutil/json_dumper.h>
#include <ftypes/ftypes-int.h>
@@ -47,10 +48,6 @@
#include <wsutil/ws_printf.h> /* ws_debug_printf */
#include <wsutil/crash_info.h>
-#ifdef HAVE_JSONGLIB
-#include <json-glib/json-glib.h>
-#endif
-
/* Ptvcursor limits */
#define SUBTREE_ONCE_ALLOCATION_NUMBER 8
#define SUBTREE_MAX_LEVELS 256
@@ -10263,21 +10260,17 @@ proto_registrar_dump_fieldcount(void)
return (gpa_hfinfo.allocated_len > PROTO_PRE_ALLOC_HF_FIELDS_MEM);
}
-#ifdef HAVE_JSONGLIB
-
-static JsonBuilder*
-elastic_add_base_mapping(JsonBuilder* builder)
+static void
+elastic_add_base_mapping(json_dumper *dumper)
{
- json_builder_set_member_name(builder, "template");
- json_builder_add_string_value(builder, "packets-*");
+ json_dumper_set_member_name(dumper, "template");
+ json_dumper_value_string(dumper, "packets-*");
- json_builder_set_member_name(builder, "settings");
- json_builder_begin_object(builder);
- json_builder_set_member_name(builder, "index.mapping.total_fields.limit");
- json_builder_add_int_value(builder, 1000000);
- json_builder_end_object(builder);
-
- return builder;
+ json_dumper_set_member_name(dumper, "settings");
+ json_dumper_begin_object(dumper);
+ json_dumper_set_member_name(dumper, "index.mapping.total_fields.limit");
+ json_dumper_value_anyf(dumper, "%d", 1000000);
+ json_dumper_end_object(dumper);
}
gchar* ws_type_to_elastic(guint type _U_)
@@ -10358,14 +10351,9 @@ proto_registrar_dump_elastic(const gchar* filter)
{
header_field_info *hfinfo;
header_field_info *parent_hfinfo;
- JsonGenerator* generator;
- JsonBuilder* builder;
- JsonNode* root;
- gsize length;
guint i;
gboolean open_object = TRUE;
const char* prev_proto = NULL;
- gchar* data;
gchar* str;
gchar** protos = NULL;
gchar* proto;
@@ -10382,30 +10370,33 @@ proto_registrar_dump_elastic(const gchar* filter)
* n.label -> where n is the indentation level and label the name of the object
*/
- builder = json_builder_new();
- json_builder_begin_object(builder); // 1.root
- builder = elastic_add_base_mapping(builder);
-
- json_builder_set_member_name(builder, "mappings");
- json_builder_begin_object(builder); // 2.mappings
- json_builder_set_member_name(builder, "pcap_file");
-
- json_builder_begin_object(builder); // 3.pcap_file
- json_builder_set_member_name(builder, "dynamic");
- json_builder_add_boolean_value(builder, FALSE);
-
- json_builder_set_member_name(builder, "properties");
- json_builder_begin_object(builder); // 4.properties
- json_builder_set_member_name(builder, "timestamp");
- json_builder_begin_object(builder); // 5.timestamp
- json_builder_set_member_name(builder, "type");
- json_builder_add_string_value(builder, "date");
- json_builder_end_object(builder); // 5.timestamp
-
- json_builder_set_member_name(builder, "layers");
- json_builder_begin_object(builder); // 5.layers
- json_builder_set_member_name(builder, "properties");
- json_builder_begin_object(builder); // 6.properties
+ json_dumper dumper = {
+ .output_file = stdout,
+ .flags = JSON_DUMPER_FLAGS_PRETTY_PRINT,
+ };
+ json_dumper_begin_object(&dumper); // 1.root
+ elastic_add_base_mapping(&dumper);
+
+ json_dumper_set_member_name(&dumper, "mappings");
+ json_dumper_begin_object(&dumper); // 2.mappings
+ json_dumper_set_member_name(&dumper, "pcap_file");
+
+ json_dumper_begin_object(&dumper); // 3.pcap_file
+ json_dumper_set_member_name(&dumper, "dynamic");
+ json_dumper_value_anyf(&dumper, "false");
+
+ json_dumper_set_member_name(&dumper, "properties");
+ json_dumper_begin_object(&dumper); // 4.properties
+ json_dumper_set_member_name(&dumper, "timestamp");
+ json_dumper_begin_object(&dumper); // 5.timestamp
+ json_dumper_set_member_name(&dumper, "type");
+ json_dumper_value_string(&dumper, "date");
+ json_dumper_end_object(&dumper); // 5.timestamp
+
+ json_dumper_set_member_name(&dumper, "layers");
+ json_dumper_begin_object(&dumper); // 5.layers
+ json_dumper_set_member_name(&dumper, "properties");
+ json_dumper_begin_object(&dumper); // 6.properties
for (i = 0; i < gpa_hfinfo.len; i++) {
if (gpa_hfinfo.hfi[i] == NULL)
@@ -10444,55 +10435,46 @@ proto_registrar_dump_elastic(const gchar* filter)
}
if (prev_proto && g_strcmp0(parent_hfinfo->abbrev, prev_proto)) {
- json_builder_end_object(builder); // 8.properties
- json_builder_end_object(builder); // 7.parent_hfinfo->abbrev
+ json_dumper_end_object(&dumper); // 8.properties
+ json_dumper_end_object(&dumper); // 7.parent_hfinfo->abbrev
open_object = TRUE;
}
prev_proto = parent_hfinfo->abbrev;
if (open_object) {
- json_builder_set_member_name(builder, parent_hfinfo->abbrev);
- json_builder_begin_object(builder); // 7.parent_hfinfo->abbrev
- json_builder_set_member_name(builder, "properties");
- json_builder_begin_object(builder); // 8.properties
+ json_dumper_set_member_name(&dumper, parent_hfinfo->abbrev);
+ json_dumper_begin_object(&dumper); // 7.parent_hfinfo->abbrev
+ json_dumper_set_member_name(&dumper, "properties");
+ json_dumper_begin_object(&dumper); // 8.properties
open_object = FALSE;
}
str = g_strdup(hfinfo->abbrev);
- json_builder_set_member_name(builder, dot_to_underscore(str));
+ json_dumper_set_member_name(&dumper, dot_to_underscore(str));
g_free(str);
- json_builder_begin_object(builder); // 9.hfinfo->abbrev
- json_builder_set_member_name(builder, "type");
- json_builder_add_string_value(builder, ws_type_to_elastic(hfinfo->type));
- json_builder_end_object(builder); // 9.hfinfo->abbrev
+ json_dumper_begin_object(&dumper); // 9.hfinfo->abbrev
+ json_dumper_set_member_name(&dumper, "type");
+ json_dumper_value_string(&dumper, ws_type_to_elastic(hfinfo->type));
+ json_dumper_end_object(&dumper); // 9.hfinfo->abbrev
}
}
if (prev_proto) {
- json_builder_end_object(builder); // 8.properties
- json_builder_end_object(builder); // 7.parent_hfinfo->abbrev
- }
-
- json_builder_end_object(builder); // 6.properties
- json_builder_end_object(builder); // 5.layers
- json_builder_end_object(builder); // 4.properties
- json_builder_end_object(builder); // 3.pcap_file
- json_builder_end_object(builder); // 2.mappings
- DISSECTOR_ASSERT(json_builder_end_object(builder)); // 1.root
-
- generator = json_generator_new();
- json_generator_set_pretty(generator, TRUE);
- root = json_builder_get_root(builder);
- json_generator_set_root(generator, root);
- json_node_free(root);
- g_object_unref(builder);
- data = json_generator_to_data(generator, &length);
- g_object_unref(generator);
- ws_debug_printf("%s\n", data);
- g_free(data);
+ json_dumper_end_object(&dumper); // 8.properties
+ json_dumper_end_object(&dumper); // 7.parent_hfinfo->abbrev
+ }
+
+ json_dumper_end_object(&dumper); // 6.properties
+ json_dumper_end_object(&dumper); // 5.layers
+ json_dumper_end_object(&dumper); // 4.properties
+ json_dumper_end_object(&dumper); // 3.pcap_file
+ json_dumper_end_object(&dumper); // 2.mappings
+ json_dumper_end_object(&dumper); // 1.root
+ gboolean ret = json_dumper_finish(&dumper);
+ DISSECTOR_ASSERT(ret);
+
g_strfreev(protos);
}
-#endif
/* Dumps the contents of the registration database to stdout. An independent
* program can take this output and format it into nice tables or HTML or
diff --git a/epan/proto.h b/epan/proto.h
index dbcbb2aeee..afe8dae6e2 100644
--- a/epan/proto.h
+++ b/epan/proto.h
@@ -2479,10 +2479,8 @@ WS_DLL_PUBLIC void proto_registrar_dump_protocols(void);
/** Dumps a glossary of the field value strings or true/false strings to STDOUT */
WS_DLL_PUBLIC void proto_registrar_dump_values(void);
-#ifdef HAVE_JSONGLIB
/** Dumps a mapping file for loading tshark output into ElasticSearch */
WS_DLL_PUBLIC void proto_registrar_dump_elastic(const gchar* filter);
-#endif
/** Dumps the number of protocol and field registrations to STDOUT.
@return FALSE if we pre-allocated enough fields, TRUE otherwise. */
diff --git a/test/baseline/elastic-mapping-ip-subset.json b/test/baseline/elastic-mapping-ip-subset.json
new file mode 100644
index 0000000000..49333ffc01
--- /dev/null
+++ b/test/baseline/elastic-mapping-ip-subset.json
@@ -0,0 +1,45 @@
+{
+ "template" : "packets-*",
+ "settings" : {
+ "index.mapping.total_fields.limit" : 1000000
+ },
+ "mappings" : {
+ "pcap_file" : {
+ "dynamic" : false,
+ "properties" : {
+ "timestamp" : {
+ "type" : "date"
+ },
+ "layers" : {
+ "properties" : {
+ "ip" : {
+ "properties" : {
+ "ip_version" : {
+ "type" : "short"
+ },
+ "ip_tos_delay" : {
+ "type" : "boolean"
+ },
+ "ip_len" : {
+ "type" : "integer"
+ },
+ "ip_dst" : {
+ "type" : "ip"
+ },
+ "ip_dst_host" : {
+ "type" : "string"
+ },
+ "ip_geoip_lat" : {
+ "type" : "float"
+ },
+ "ip_opt_padding" : {
+ "type" : "byte"
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+}
diff --git a/test/suite_clopts.py b/test/suite_clopts.py
index 722769b08d..4a0d7b10ce 100644
--- a/test/suite_clopts.py
+++ b/test/suite_clopts.py
@@ -9,6 +9,8 @@
#
'''Command line option tests'''
+import json
+import os.path
import subprocess
import subprocesstest
import fixtures
@@ -181,6 +183,21 @@ class case_tshark_dump_glossaries(subprocesstest.SubprocessTestCase):
self.runProcess((cmd_tshark, '-G', 'plugins'), env=base_env)
self.assertGreaterEqual(self.countOutput('dissector'), 10, 'Fewer than 10 dissector plugins found')
+ def test_tshark_elastic_mapping(self, cmd_tshark, dirs, base_env):
+ def get_ip_props(obj):
+ return obj['mappings']['pcap_file']['properties']['layers']['properties']['ip']['properties']
+ baseline_file = os.path.join(dirs.baseline_dir, 'elastic-mapping-ip-subset.json')
+ with open(baseline_file) as f:
+ expected_obj = json.load(f)
+ keys_to_check = get_ip_props(expected_obj).keys()
+ proc = self.assertRun((cmd_tshark, '-G', 'elastic-mapping', '--elastic-mapping-filter', 'ip'))
+ actual_obj = json.loads(proc.stdout_str)
+ ip_props = get_ip_props(actual_obj)
+ for key in list(ip_props.keys()):
+ if key not in keys_to_check:
+ del ip_props[key]
+ self.assertEqual(actual_obj, expected_obj)
+
@fixtures.mark_usefixtures('test_env')
@fixtures.uses_fixtures
diff --git a/tshark.c b/tshark.c
index 7d97cdaa2f..d2b1e59dd7 100644
--- a/tshark.c
+++ b/tshark.c
@@ -140,9 +140,7 @@
*/
#define LONGOPT_COLOR (65536+1000)
#define LONGOPT_NO_DUPLICATE_KEYS (65536+1001)
-#ifdef HAVE_JSONGLIB
#define LONGOPT_ELASTIC_MAPPING_FILTER (65536+1002)
-#endif
#if 0
#define tshark_debug(...) g_warning(__VA_ARGS__)
@@ -439,10 +437,8 @@ print_usage(FILE *output)
fprintf(output, " --no-duplicate-keys If -T json is specified, merge duplicate keys in an object\n");
fprintf(output, " into a single key with as value a json array containing all\n");
fprintf(output, " values\n");
-#ifdef HAVE_JSONGLIB
fprintf(output, " --elastic-mapping-filter <protocols> If -G elastic-mapping is specified, put only the\n");
fprintf(output, " specified protocols within the mapping file\n");
-#endif
fprintf(output, "\n");
fprintf(output, "Miscellaneous:\n");
@@ -479,9 +475,7 @@ glossary_option_help(void)
fprintf(output, " -G column-formats dump column format codes and exit\n");
fprintf(output, " -G decodes dump \"layer type\"/\"decode as\" associations and exit\n");
fprintf(output, " -G dissector-tables dump dissector table names, types, and properties\n");
-#ifdef HAVE_JSONGLIB
fprintf(output, " -G elastic-mapping dump ElasticSearch mapping file\n");
-#endif
fprintf(output, " -G fieldcount dump count of header fields and exit\n");
fprintf(output, " -G fields dump fields glossary and exit\n");
fprintf(output, " -G ftypes dump field type basic and descriptive names\n");
@@ -683,9 +677,7 @@ real_main(int argc, char *argv[])
{"export-objects", required_argument, NULL, LONGOPT_EXPORT_OBJECTS},
{"color", no_argument, NULL, LONGOPT_COLOR},
{"no-duplicate-keys", no_argument, NULL, LONGOPT_NO_DUPLICATE_KEYS},
-#ifdef HAVE_JSONGLIB
{"elastic-mapping-filter", required_argument, NULL, LONGOPT_ELASTIC_MAPPING_FILTER},
-#endif
{0, 0, 0, 0 }
};
gboolean arg_error = FALSE;
@@ -729,9 +721,7 @@ real_main(int argc, char *argv[])
gchar *volatile pdu_export_arg = NULL;
char *volatile exp_pdu_filename = NULL;
exp_pdu_t exp_pdu_tap_data;
-#ifdef HAVE_JSONGLIB
const gchar* elastic_mapping_filter = NULL;
-#endif
/*
* The leading + ensures that getopt_long() does not permute the argv[]
@@ -866,11 +856,9 @@ real_main(int argc, char *argv[])
case 'X':
ex_opt_add(optarg);
break;
-#ifdef HAVE_JSONGLIB
case LONGOPT_ELASTIC_MAPPING_FILTER:
elastic_mapping_filter = optarg;
break;
-#endif
default:
break;
}
@@ -973,10 +961,8 @@ real_main(int argc, char *argv[])
write_prefs(NULL);
else if (strcmp(argv[2], "dissector-tables") == 0)
dissector_dump_dissector_tables();
-#ifdef HAVE_JSONGLIB
else if (strcmp(argv[2], "elastic-mapping") == 0)
proto_registrar_dump_elastic(elastic_mapping_filter);
-#endif
else if (strcmp(argv[2], "fieldcount") == 0) {
/* return value for the test suite */
exit_status = proto_registrar_dump_fieldcount();
diff --git a/wsutil/CMakeLists.txt b/wsutil/CMakeLists.txt
index dfc649932a..9af601854f 100644
--- a/wsutil/CMakeLists.txt
+++ b/wsutil/CMakeLists.txt
@@ -43,6 +43,7 @@ set(WSUTIL_PUBLIC_HEADERS
inet_ipv6.h
interface.h
jsmn.h
+ json_dumper.h
mpeg-audio.h
netlink.h
nstime.h
@@ -99,6 +100,7 @@ set(WSUTIL_COMMON_FILES
inet_addr.c
interface.c
jsmn.c
+ json_dumper.c
mpeg-audio.c
nstime.c
cpu_info.c
diff --git a/wsutil/json_dumper.c b/wsutil/json_dumper.c
new file mode 100644
index 0000000000..ebac957617
--- /dev/null
+++ b/wsutil/json_dumper.c
@@ -0,0 +1,285 @@
+/* wsjson.h
+ * Routines for serializing data as JSON.
+ *
+ * Copyright 2018, Peter Wu <peter@lekensteyn.nl>
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "json_dumper.h"
+
+/*
+ * json_dumper.state[current_depth] describes a nested element:
+ * - type: none/object/array/value
+ * - has_name: Whether the object member name was set.
+ */
+enum json_dumper_element_type {
+ JSON_DUMPER_TYPE_NONE = 0,
+ JSON_DUMPER_TYPE_VALUE = 1,
+ JSON_DUMPER_TYPE_OBJECT = 2,
+ JSON_DUMPER_TYPE_ARRAY = 3,
+};
+#define JSON_DUMPER_TYPE(state) ((enum json_dumper_element_type)((state) & 3))
+#define JSON_DUMPER_HAS_NAME (1 << 2)
+
+#define JSON_DUMPER_FLAGS_ERROR (1 << 16) /* Output flag: an error occurred. */
+
+enum json_dumper_change {
+ JSON_DUMPER_BEGIN,
+ JSON_DUMPER_END,
+ JSON_DUMPER_SET_NAME,
+ JSON_DUMPER_SET_VALUE,
+ JSON_DUMPER_FINISH,
+};
+
+static void
+json_puts_string(FILE *fp, const char *str)
+{
+ static const char json_cntrl[0x20][6] = {
+ "u0000", "u0001", "u0002", "u0003", "u0004", "u0005", "u0006", "u0007", "b", "t", "n", "u000b", "f", "r", "u000e", "u000f",
+ "u0010", "u0011", "u0012", "u0013", "u0014", "u0015", "u0016", "u0017", "u0018", "u0019", "u001a", "u001b", "u001c", "u001d", "u001e", "u001f"
+ };
+
+ fputc('"', fp);
+ for (int i = 0; str[i]; i++) {
+ if ((guint)str[i] < 0x20) {
+ fputc('\\', fp);
+ fputs(json_cntrl[(guint)str[i]], fp);
+ } else {
+ if (str[i] == '\\' || str[i] == '"') {
+ fputc('\\', fp);
+ }
+ fputc(str[i], fp);
+ }
+ }
+ fputc('"', fp);
+}
+
+/**
+ * Checks that the dumper state is valid for a new change. Any error will be
+ * sticky and prevent further dumps from succeeding.
+ */
+static gboolean
+json_dumper_check_state(json_dumper *dumper, enum json_dumper_change change, enum json_dumper_element_type type)
+{
+ if ((dumper->flags & JSON_DUMPER_FLAGS_ERROR)) {
+ return FALSE;
+ }
+
+ int depth = dumper->current_depth;
+ if (depth < 0 || depth >= JSON_DUMPER_MAX_DEPTH) {
+ /* Corrupted state, no point in continuing. */
+ dumper->flags |= JSON_DUMPER_FLAGS_ERROR;
+ return FALSE;
+ }
+
+ guint8 prev_state = depth > 0 ? dumper->state[depth - 1] : 0;
+ enum json_dumper_element_type prev_type = JSON_DUMPER_TYPE(prev_state);
+
+ gboolean ok = FALSE;
+ switch (change) {
+ case JSON_DUMPER_BEGIN:
+ ok = depth + 1 < JSON_DUMPER_MAX_DEPTH;
+ break;
+ case JSON_DUMPER_END:
+ ok = prev_type == type && !(prev_state & JSON_DUMPER_HAS_NAME);
+ break;
+ case JSON_DUMPER_SET_NAME:
+ /* An object name can only be set once before a value is set. */
+ ok = prev_type == JSON_DUMPER_TYPE_OBJECT && !(prev_state & JSON_DUMPER_HAS_NAME);
+ break;
+ case JSON_DUMPER_SET_VALUE:
+ if (prev_type == JSON_DUMPER_TYPE_OBJECT) {
+ ok = (prev_state & JSON_DUMPER_HAS_NAME);
+ } else if (prev_type == JSON_DUMPER_TYPE_ARRAY) {
+ ok = TRUE;
+ } else {
+ ok = JSON_DUMPER_TYPE(dumper->state[depth]) == JSON_DUMPER_TYPE_NONE;
+ }
+ break;
+ case JSON_DUMPER_FINISH:
+ ok = depth == 0;
+ break;
+ }
+ if (!ok) {
+ dumper->flags |= JSON_DUMPER_FLAGS_ERROR;
+ }
+ return ok;
+}
+
+static void
+print_newline_indent(const json_dumper *dumper, int depth)
+{
+ if ((dumper->flags & JSON_DUMPER_FLAGS_PRETTY_PRINT)) {
+ fputc('\n', dumper->output_file);
+ for (int i = 0; i < depth; i++) {
+ fputs(" ", dumper->output_file);
+ }
+ }
+}
+
+/**
+ * Prints commas, newlines and indentation (if necessary). Used for array
+ * values, object names and normal values (strings, etc.).
+ */
+static void
+prepare_token(json_dumper *dumper)
+{
+ if (dumper->current_depth == 0) {
+ // not part of an array or object.
+ return;
+ }
+ guint8 prev_state = dumper->state[dumper->current_depth - 1];
+
+ // While processing the object value, reset the key state as it is consumed.
+ dumper->state[dumper->current_depth - 1] &= ~JSON_DUMPER_HAS_NAME;
+
+ switch (JSON_DUMPER_TYPE(prev_state)) {
+ case JSON_DUMPER_TYPE_OBJECT:
+ if ((prev_state & JSON_DUMPER_HAS_NAME)) {
+ // Object key already set, value follows. No indentation needed.
+ return;
+ }
+ break;
+ case JSON_DUMPER_TYPE_ARRAY:
+ break;
+ default:
+ // Initial values do not need indentation.
+ return;
+ }
+
+ if (dumper->state[dumper->current_depth]) {
+ fputc(',', dumper->output_file);
+ }
+ print_newline_indent(dumper, dumper->current_depth);
+}
+
+/**
+ * Common code to close an object/array, printing a closing character (and if
+ * necessary, it is preceded by newline and indentation).
+ */
+static void
+finish_token(const json_dumper *dumper, char close_char)
+{
+ // if the object/array was non-empty, add a newline and indentation.
+ if (dumper->state[dumper->current_depth]) {
+ print_newline_indent(dumper, dumper->current_depth - 1);
+ }
+ fputc(close_char, dumper->output_file);
+}
+
+void
+json_dumper_begin_object(json_dumper *dumper)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_BEGIN, JSON_DUMPER_TYPE_OBJECT)) {
+ return;
+ }
+
+ prepare_token(dumper);
+ fputc('{', dumper->output_file);
+
+ dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_OBJECT;
+ ++dumper->current_depth;
+ dumper->state[dumper->current_depth] = 0;
+}
+
+void
+json_dumper_set_member_name(json_dumper *dumper, const char *name)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_NAME, JSON_DUMPER_TYPE_NONE)) {
+ return;
+ }
+
+ prepare_token(dumper);
+ json_puts_string(dumper->output_file, name);
+ fputc(':', dumper->output_file);
+ if ((dumper->flags & JSON_DUMPER_FLAGS_PRETTY_PRINT)) {
+ fputc(' ', dumper->output_file);
+ }
+
+ dumper->state[dumper->current_depth - 1] |= JSON_DUMPER_HAS_NAME;
+}
+
+void
+json_dumper_end_object(json_dumper *dumper)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_END, JSON_DUMPER_TYPE_OBJECT)) {
+ return;
+ }
+
+ finish_token(dumper, '}');
+
+ --dumper->current_depth;
+}
+
+void
+json_dumper_begin_array(json_dumper *dumper)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_BEGIN, JSON_DUMPER_TYPE_ARRAY)) {
+ return;
+ }
+
+ prepare_token(dumper);
+ fputc('[', dumper->output_file);
+
+ dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_ARRAY;
+ ++dumper->current_depth;
+ dumper->state[dumper->current_depth] = 0;
+}
+
+void
+json_dumper_end_array(json_dumper *dumper)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_END, JSON_DUMPER_TYPE_ARRAY)) {
+ return;
+ }
+
+ finish_token(dumper, ']');
+
+ --dumper->current_depth;
+}
+
+void
+json_dumper_value_string(json_dumper *dumper, const char *value)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_VALUE, JSON_DUMPER_TYPE_VALUE)) {
+ return;
+ }
+
+ prepare_token(dumper);
+ json_puts_string(dumper->output_file, value);
+
+ dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_VALUE;
+}
+
+void
+json_dumper_value_anyf(json_dumper *dumper, const char *format, ...)
+{
+ va_list ap;
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_VALUE, JSON_DUMPER_TYPE_VALUE)) {
+ return;
+ }
+
+ prepare_token(dumper);
+ va_start(ap, format);
+ vfprintf(dumper->output_file, format, ap);
+ va_end(ap);
+
+ dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_VALUE;
+}
+
+gboolean
+json_dumper_finish(json_dumper *dumper)
+{
+ if (!json_dumper_check_state(dumper, JSON_DUMPER_FINISH, JSON_DUMPER_TYPE_NONE)) {
+ return FALSE;
+ }
+
+ fputc('\n', dumper->output_file);
+ dumper->state[0] = 0;
+ return TRUE;
+}
diff --git a/wsutil/json_dumper.h b/wsutil/json_dumper.h
new file mode 100644
index 0000000000..98ce99a3e7
--- /dev/null
+++ b/wsutil/json_dumper.h
@@ -0,0 +1,107 @@
+/* wsjson.h
+ * Routines for serializing data as JSON.
+ *
+ * Copyright 2018, Peter Wu <peter@lekensteyn.nl>
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef __JSON_DUMPER_H__
+#define __JSON_DUMPER_H__
+
+#include "ws_symbol_export.h"
+#include <glib.h>
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Example:
+ *
+ * json_dumper dumper = {
+ * .output_file = stdout,
+ * .flags = JSON_DUMPER_FLAGS_PRETTY_PRINT,
+ * };
+ * json_dumper_begin_object(&dumper);
+ * json_dumper_set_member_name(&dumper, "key");
+ * json_dumper_value_string(&dumper, "value");
+ * json_dumper_set_member_name(&dumper, "array");
+ * json_dumper_begin_array(&dumper);
+ * json_dumper_value_anyf(&dumper, "true");
+ * json_dumper_value_anyf(&dumper, "1.0");
+ * json_dumper_begin_object(&dumper);
+ * json_dumper_end_object(&dumper);
+ * json_dumper_begin_array(&dumper);
+ * json_dumper_end_array(&dumper);
+ * json_dumper_end_array(&dumper);
+ * json_dumper_end_object(&dumper);
+ * json_dumper_finish(&dumper);
+ */
+
+/** Maximum object/array nesting depth. */
+#define JSON_DUMPER_MAX_DEPTH 15
+typedef struct json_dumper {
+ FILE *output_file; /**< Output file, must be set. */
+#define JSON_DUMPER_FLAGS_PRETTY_PRINT (1 << 0) /* Enable pretty printing. */
+ int flags;
+ /* for internal use, initialize with zeroes. */
+ int current_depth;
+ guint8 state[JSON_DUMPER_MAX_DEPTH];
+} json_dumper;
+
+WS_DLL_PUBLIC void
+json_dumper_begin_object(json_dumper *dumper);
+
+WS_DLL_PUBLIC void
+json_dumper_set_member_name(json_dumper *dumper, const char *name);
+
+WS_DLL_PUBLIC void
+json_dumper_end_object(json_dumper *dumper);
+
+WS_DLL_PUBLIC void
+json_dumper_begin_array(json_dumper *dumper);
+
+WS_DLL_PUBLIC void
+json_dumper_end_array(json_dumper *dumper);
+
+WS_DLL_PUBLIC void
+json_dumper_value_string(json_dumper *dumper, const char *value);
+
+/**
+ * Dump number, "true", "false" or "null" values.
+ */
+WS_DLL_PUBLIC void
+json_dumper_value_anyf(json_dumper *dumper, const char *format, ...)
+G_GNUC_PRINTF(2, 3);
+
+/**
+ * Finishes dumping data. Returns TRUE if everything is okay and FALSE if
+ * something went wrong (open/close mismatch, missing values, etc.).
+ */
+WS_DLL_PUBLIC gboolean
+json_dumper_finish(json_dumper *dumper);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __JSON_DUMPER_H__ */
+
+/*
+ * Editor modelines - https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */