Add a full native JSON parser to Kore.

Mostly compliant, ignores \uXXXX in strings for now.

New API functions:

void kore_json_init(struct kore_json *json, const u_int8_t *data, size_t len);
  - Prepares JSON data for parsing.

int kore_json_parse(struct kore_json *json)
  - Parses the JSON data prepared via kore_json_init. Returns KORE_RESULT_ERROR
    if parsing failed or KORE_RESULT_OK if it succeeded.

struct kore_json_item *kore_json_get(struct kore_json *json, const char *path,
                                     int type);
  - Try to find the object matching a given search patch and type.

  eg, given a JSON structure of:
    {
      "reasons": {
        "strings": [
          "first reason",
          "second"
        ]
      }
    }

  one can obtain the second element in the reasons.strings array via:

    item = kore_json_get(json, "reasons/strings[0]", KORE_JSON_TYPE_STRING);

  Returns NULL if the item was not found or a type mismatch was hit,
  otherwise will return the item of that type.

  The kore_json_item data structure has a data member that contains the
  relevant bits depending on the type:

    KORE_JSON_TYPE_ARRAY, KORE_JSON_TYPE_OBJECT:
      the data.items member is valid.

    KORE_JSON_TYPE_STRING:
      the data.string member is valid.

    KORE_JSON_TYPE_NUMBER:
      the data.number member is valid.

    KORE_JSON_TYPE_LITERAL:
      the data.literal member is valid.

void kore_json_cleanup(struct kore_json *json);
  - Cleanup any resources

const char *kore_json_strerror(struct kore_json *json);
  - Return pointer to human readable error string.

Makefile

@@ -15,8 +15,8 @@ PLATFORM=platform.h
 VERSION=src/version.c
 
 S_SRC=	src/kore.c src/buf.c src/config.c src/connection.c \
-	src/domain.c src/filemap.c src/fileref.c src/mem.c src/msg.c \
-	src/module.c src/net.c src/pool.c src/runtime.c src/timer.c \
+	src/domain.c src/filemap.c src/fileref.c src/json.c src/mem.c \
+	src/msg.c src/module.c src/net.c src/pool.c src/runtime.c src/timer.c \
 	src/utils.c src/worker.c src/keymgr.c $(VERSION)
 
 FEATURES=

include/kore/kore.h

@@ -464,6 +464,76 @@ struct kore_buf {
 	size_t			offset;
 };
 
+#define KORE_JSON_TYPE_OBJECT		1
+#define KORE_JSON_TYPE_ARRAY		2
+#define KORE_JSON_TYPE_STRING		3
+#define KORE_JSON_TYPE_NUMBER		4
+#define KORE_JSON_TYPE_LITERAL		5
+
+#define KORE_JSON_FALSE			0
+#define KORE_JSON_TRUE			1
+#define KORE_JSON_NULL			2
+
+#define KORE_JSON_DEPTH_MAX		10
+
+#define KORE_JSON_ERR_NONE		0
+#define KORE_JSON_ERR_INVALID_OBJECT	1
+#define KORE_JSON_ERR_INVALID_ARRAY	2
+#define KORE_JSON_ERR_INVALID_STRING	3
+#define KORE_JSON_ERR_INVALID_NUMBER	4
+#define KORE_JSON_ERR_INVALID_LITERAL	5
+#define KORE_JSON_ERR_DEPTH		6
+#define KORE_JSON_ERR_EOF		7
+#define KORE_JSON_ERR_INVALID_JSON	8
+#define KORE_JSON_ERR_INVALID_SEARCH	9
+#define KORE_JSON_ERR_NOT_FOUND		10
+#define KORE_JSON_ERR_TYPE_MISMATCH	11
+#define KORE_JSON_ERR_LAST		KORE_JSON_ERR_TYPE_MISMATCH
+
+#define kore_json_object(j, p)		\
+    kore_json_get(j, p, KORE_JSON_TYPE_OBJECT)
+
+#define kore_json_array(j, p)		\
+    kore_json_get(j, p, KORE_JSON_TYPE_ARRAY)
+
+#define kore_json_string(j, p)		\
+    kore_json_get(j, p, KORE_JSON_TYPE_STRING)
+
+#define kore_json_number(j, p)		\
+    kore_json_get(j, p, KORE_JSON_TYPE_NUMBER)
+
+#define kore_json_literal(j, p)		\
+    kore_json_get(j, p, KORE_JSON_TYPE_LITERAL)
+
+struct kore_json {
+	const u_int8_t			*data;
+	int				depth;
+	int				error;
+	size_t				length;
+	size_t				offset;
+
+	struct kore_buf			tmpbuf;
+	struct kore_json_item		*root;
+};
+
+struct kore_json_item {
+	int				type;
+	char				*name;
+	struct kore_json_item		*parent;
+
+	union {
+		TAILQ_HEAD(, kore_json_item)	items;
+		char				*string;
+		double				number;
+		int				literal;
+	} data;
+
+	int				(*parse)(struct kore_json *,
+					    struct kore_json_item *);
+
+	TAILQ_ENTRY(kore_json_item)	list;
+};
+
 struct kore_pool_region {
 	void				*start;
 	size_t				length;
@@ -874,6 +944,13 @@ void	kore_buf_appendv(struct kore_buf *, const char *, va_list);
 void	kore_buf_replace_string(struct kore_buf *,
 	    const char *, const void *, size_t);
 
+int	kore_json_parse(struct kore_json *);
+void	kore_json_cleanup(struct kore_json *);
+void	kore_json_init(struct kore_json *, const u_int8_t *, size_t);
+
+const char		*kore_json_strerror(struct kore_json *);
+struct kore_json_item	*kore_json_get(struct kore_json *, const char *, int);
+
 void	kore_keymgr_run(void);
 void	kore_keymgr_cleanup(int);