From eb2299a0897577048205e4d8a331168d82ce09d0 Mon Sep 17 00:00:00 2001

From: Noriko Hosoi <nhosoi@momo7.localdomain>

Date: Thu, 26 Jul 2018 17:18:38 -0700

Subject: [PATCH] Add a parameter skipempty to the json field type.

If skipempty is set as follows, empty json objects are dropped from

the parsed result.

  %field_name:json:skipempty%

If any parameter other than "skipempty" is given ("bogus" in this

example), an error message "invalid flag for JSON parser: bogus"

is issued.

---

 src/parser.c                  | 127 ++++++++++++++++++++++++++++++++++++++++++

 src/parser.h                  |   2 +-

 src/pdag.c                    |   2 +-

 3 files changed, 129 insertions(+), 2 deletions(-)

diff --git a/src/parser.c b/src/parser.c

index 77407c6..6736c6f 100644

--- a/src/parser.c

+++ b/src/parser.c

@@ -2325,6 +2325,85 @@ PARSER_Parse(v2IPTables)

 	return r;

 }

+/*

+ * Delete children of the given object if it has children and they are empty.

+ *

+ * return 0 if object is not empty

+ * return 1 if object is empty

+ * return < 0 if error

+ *

+ * Caller should do this:

+ * if (jsonSkipEmpty(obj) > 0) {

+ *     json_object_put(obj);

+ *     obj = NULL;

+ * }

+ * or otherwise not use obj if jsonSkipEmpty returns > 0.

+ */

+static int

+jsonSkipEmpty(struct json_object *__restrict__ json)

+{

+	int rc = 0;

+	struct json_object *val = NULL;

+

+	if(json == NULL) {

+		rc = 1;

+		goto finalize_it;

+	}

+

+	switch (json_object_get_type(json)) {

+	case json_type_string:

+		rc = json_object_get_string_len(json) == 0;

+		break;

+	case json_type_array:

+	{

+		int i;

+		int arrayLen = json_object_array_length(json);

+		for (i = 0 ; i < arrayLen ; ++i) {

+			val = json_object_array_get_idx(json, i);

+			if ((rc = jsonSkipEmpty(val)) > 0) {

+				/* delete the empty item and reset the index and arrayLen */

+				json_object_array_del_idx(json, i--);

+				arrayLen = json_object_array_length(json);

+			} else if (rc < 0) {

+				goto finalize_it;

+			}

+		}

+		rc = json_object_array_length(json) == 0;

+		break;

+	}

+	case json_type_object:

+	{

+		struct json_object_iterator it = json_object_iter_begin(json);

+		struct json_object_iterator itEnd = json_object_iter_end(json);

+		while (!json_object_iter_equal(&it, &itEnd)) {

+			val = json_object_iter_peek_value(&it);

+			if ((rc = jsonSkipEmpty(val)) > 0) {

+				json_object_object_del(json, json_object_iter_peek_name(&it);;

+			} else if (rc < 0) {

+				goto finalize_it;

+			}

+			json_object_iter_next(&it);

+		}

+		rc = json_object_object_length(json) == 0;

+	}

+	case json_type_null:

+	case json_type_boolean:

+	case json_type_double:

+	case json_type_int:

+	default: break;

+	}

+finalize_it:

+	return rc;

+}

+

+/* 

+ * Parameters for field type json

+ *   skipempty - skips empty json objects.

+ *             - %field_name:json:skipempty%

+ */

+struct data_JSON {

+	int skipempty;

+};

 /**

  * Parse JSON. This parser tries to find JSON data inside a message.

  * If it finds valid JSON, it will extract it. Extra data after the

@@ -2340,6 +2419,7 @@ PARSER_Parse(v2IPTables)

 PARSER_Parse(JSON)

 	const size_t i = *offs;

 	struct json_tokener *tokener = NULL;

+	struct data_JSON *const data = (struct data_JSON*) pdata;

 	if(npb->str[i] != '{' && npb->str[i] != ']') {

 		/* this can't be json, see RFC4627, Sect. 2

@@ -2368,6 +2448,20 @@ PARSER_Parse(JSON)

 	if(value == NULL) {

 		json_object_put(json);

 	} else {

+		if (data && data->skipempty) {

+			int rc = jsonSkipEmpty(json);

+			if (rc < 0) {

+				json_object_put(json);

+				FAIL(LN_WRONGPARSER);

+			} else if (rc > 0) {

+				/* 

+				 * json value is empty.

+				 * E.g., {"message":""}, {"message":[]}, {"message":{}}

+				 */

+				json_object_put(json);

+				FAIL(0);

+			}

+		}

 		*value = json;

 	}

@@ -2376,7 +2470,40 @@ PARSER_Parse(JSON)

 		json_tokener_free(tokener);

 	return r;

 }

+PARSER_Construct(JSON)

+{

+	int r = 0;

+	struct json_object *ed;

+	struct data_JSON *data = NULL;

+	char *flag;

+	if(json == NULL)

+		goto done;

+

+	if(json_object_object_get_ex(json, "extradata", &ed) == 0) {

+		/* No JSON parameter */

+		goto done;

+	}

+	data = (struct data_JSON*) calloc(1, sizeof(struct data_JSON));

+	flag = json_object_get_string(ed);

+	if (strcasecmp(flag, "skipempty") == 0) {

+		data->skipempty = 1;

+	} else {

+		ln_errprintf(ctx, 0, "invalid flag for JSON parser: %s", flag);

+		r = LN_BADCONFIG;

+		goto done;

+	}

+	*pdata = data;

+done:

+	if(r != 0) {

+		free(data);

+	}

+	return r;

+}

+PARSER_Destruct(JSON)

+{

+	free(pdata);

+}

 /* check if a char is valid inside a name of a NameValue list

  * The set of valid characters may be extended if there is good

diff --git a/src/parser.h b/src/parser.h

index 38be62d..5b4a821 100644

--- a/src/parser.h

+++ b/src/parser.h

@@ -70,7 +70,7 @@ PARSERDEF_NO_DATA(Time24hr);

 PARSERDEF_NO_DATA(Duration);

 PARSERDEF_NO_DATA(IPv4);

 PARSERDEF_NO_DATA(IPv6);

-PARSERDEF_NO_DATA(JSON);

+PARSERDEF(JSON);

 PARSERDEF_NO_DATA(CEESyslog);

 PARSERDEF_NO_DATA(v2IPTables);

 PARSERDEF_NO_DATA(CiscoInterfaceSpec);

diff --git a/src/pdag.c b/src/pdag.c

index 0768e99..9feb755 100644

--- a/src/pdag.c

+++ b/src/pdag.c

@@ -90,7 +90,7 @@ static struct ln_parser_info parser_lookup_table[] = {

 	PARSER_ENTRY_NO_DATA("duration", Duration, 16),

 	PARSER_ENTRY_NO_DATA("cisco-interface-spec", CiscoInterfaceSpec, 4),

 	PARSER_ENTRY_NO_DATA("name-value-list", NameValue, 8),

-	PARSER_ENTRY_NO_DATA("json", JSON, 4),

+	PARSER_ENTRY("json", JSON, 4),

 	PARSER_ENTRY_NO_DATA("cee-syslog", CEESyslog, 4),

 	PARSER_ENTRY_NO_DATA("mac48", MAC48, 16),

 	PARSER_ENTRY_NO_DATA("cef", CEF, 4),