lws-lejp.h

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/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
 
/** \defgroup lejp JSON parser
 * ##JSON parsing related functions
 * \ingroup lwsapi
 *
 * LEJP is an extremely lightweight JSON stream parser included in lws.
 */
//@{
struct lejp_ctx;
 
#if !defined(LWS_ARRAY_SIZE)
#define LWS_ARRAY_SIZE(_x) (sizeof(_x) / sizeof(_x[0]))
#endif
#define LEJP_FLAG_WS_KEEP 64
#define LEJP_FLAG_WS_COMMENTLINE 32
 
enum lejp_states {
        LEJP_IDLE = 0,
        LEJP_MEMBERS = 1,
        LEJP_M_P = 2,
        LEJP_MP_STRING = LEJP_FLAG_WS_KEEP | 3,
        LEJP_MP_STRING_ESC = LEJP_FLAG_WS_KEEP | 4,
        LEJP_MP_STRING_ESC_U1 = LEJP_FLAG_WS_KEEP | 5,
        LEJP_MP_STRING_ESC_U2 = LEJP_FLAG_WS_KEEP | 6,
        LEJP_MP_STRING_ESC_U3 = LEJP_FLAG_WS_KEEP | 7,
        LEJP_MP_STRING_ESC_U4 = LEJP_FLAG_WS_KEEP | 8,
        LEJP_MP_DELIM = 9,
        LEJP_MP_VALUE = 10,
        LEJP_MP_VALUE_NUM_INT = LEJP_FLAG_WS_KEEP | 11,
        LEJP_MP_VALUE_NUM_EXP = LEJP_FLAG_WS_KEEP | 12,
        LEJP_MP_VALUE_TOK = LEJP_FLAG_WS_KEEP | 13,
        LEJP_MP_COMMA_OR_END = 14,
        LEJP_MP_ARRAY_END = 15,
};
 
enum lejp_reasons {
        LEJP_CONTINUE = -1,
        LEJP_REJECT_IDLE_NO_BRACE = -2,
        LEJP_REJECT_MEMBERS_NO_CLOSE = -3,
        LEJP_REJECT_MP_NO_OPEN_QUOTE = -4,
        LEJP_REJECT_MP_STRING_UNDERRUN = -5,
        LEJP_REJECT_MP_ILLEGAL_CTRL = -6,
        LEJP_REJECT_MP_STRING_ESC_ILLEGAL_ESC = -7,
        LEJP_REJECT_ILLEGAL_HEX = -8,
        LEJP_REJECT_MP_DELIM_MISSING_COLON = -9,
        LEJP_REJECT_MP_DELIM_BAD_VALUE_START = -10,
        LEJP_REJECT_MP_VAL_NUM_INT_NO_FRAC = -11,
        LEJP_REJECT_MP_VAL_NUM_FORMAT = -12,
        LEJP_REJECT_MP_VAL_NUM_EXP_BAD_EXP = -13,
        LEJP_REJECT_MP_VAL_TOK_UNKNOWN = -14,
        LEJP_REJECT_MP_C_OR_E_UNDERF = -15,
        LEJP_REJECT_MP_C_OR_E_NOTARRAY = -16,
        LEJP_REJECT_MP_ARRAY_END_MISSING = -17,
        LEJP_REJECT_STACK_OVERFLOW = -18,
        LEJP_REJECT_MP_DELIM_ISTACK = -19,
        LEJP_REJECT_NUM_TOO_LONG = -20,
        LEJP_REJECT_MP_C_OR_E_NEITHER = -21,
        LEJP_REJECT_UNKNOWN = -22,
        LEJP_REJECT_CALLBACK = -23
};
 
#define LEJP_FLAG_CB_IS_VALUE 64
 
enum lejp_callbacks {
        LEJPCB_CONSTRUCTED      = 0,
        LEJPCB_DESTRUCTED       = 1,
 
        LEJPCB_START            = 2,
        LEJPCB_COMPLETE         = 3,
        LEJPCB_FAILED           = 4,
 
        LEJPCB_PAIR_NAME        = 5,
 
        LEJPCB_VAL_TRUE         = LEJP_FLAG_CB_IS_VALUE | 6,
        LEJPCB_VAL_FALSE        = LEJP_FLAG_CB_IS_VALUE | 7,
        LEJPCB_VAL_NULL         = LEJP_FLAG_CB_IS_VALUE | 8,
        LEJPCB_VAL_NUM_INT      = LEJP_FLAG_CB_IS_VALUE | 9,
        LEJPCB_VAL_NUM_FLOAT    = LEJP_FLAG_CB_IS_VALUE | 10,
        LEJPCB_VAL_STR_START    = 11, /* notice handle separately */
        LEJPCB_VAL_STR_CHUNK    = LEJP_FLAG_CB_IS_VALUE | 12,
        LEJPCB_VAL_STR_END      = LEJP_FLAG_CB_IS_VALUE | 13,
 
        LEJPCB_ARRAY_START      = 14,
        LEJPCB_ARRAY_END        = 15,
 
        LEJPCB_OBJECT_START     = 16,
        LEJPCB_OBJECT_END       = 17,
 
        LEJPCB_USER_START       = 32,
};
 
/**
 * _lejp_callback() - User parser actions
 * \param ctx:  LEJP context
 * \param reason:       Callback reason
 *
 *      Your user callback is associated with the context at construction time,
 *      and receives calls as the parsing progresses.
 *
 *      All of the callbacks may be ignored and just return 0.
 *
 *      The reasons it might get called, found in @reason, are:
 *
 *  LEJPCB_CONSTRUCTED:  The context was just constructed... you might want to
 *              perform one-time allocation for the life of the context.
 *
 *  LEJPCB_DESTRUCTED:  The context is being destructed... if you made any
 *              allocations at construction-time, you can free them now
 *
 *  LEJPCB_START:       Parsing is beginning at the first byte of input
 *
 *  LEJPCB_COMPLETE:    Parsing has completed successfully.  You'll get a 0 or
 *                      positive return code from lejp_parse indicating the
 *                      amount of unused bytes left in the input buffer
 *
 *  LEJPCB_FAILED:      Parsing failed.  You'll get a negative error code
 *                      returned from lejp_parse
 *
 *  LEJPCB_PAIR_NAME:   When a "name":"value" pair has had the name parsed,
 *                      this callback occurs.  You can find the new name at
 *                      the end of ctx->path[]
 *
 *  LEJPCB_VAL_TRUE:    The "true" value appeared
 *
 *  LEJPCB_VAL_FALSE:   The "false" value appeared
 *
 *  LEJPCB_VAL_NULL:    The "null" value appeared
 *
 *  LEJPCB_VAL_NUM_INT: A string representing an integer is in ctx->buf
 *
 *  LEJPCB_VAL_NUM_FLOAT: A string representing a float is in ctx->buf
 *
 *  LEJPCB_VAL_STR_START: We are starting to parse a string, no data yet
 *
 *  LEJPCB_VAL_STR_CHUNK: We filled the string buffer in the ctx, but it's not
 *                        the end of the string.  We produce this to spill the
 *                        intermediate buffer to the user code, so we can handle
 *                        huge JSON strings using only the small buffer in the
 *                        ctx.  If the whole JSON string fits in the ctx buffer,
 *                        you won't get these callbacks.
 *
 *  LEJPCB_VAL_STR_END: String parsing has completed, the last chunk of the
 *                      string is in ctx->buf.
 *
 *  LEJPCB_ARRAY_START: An array started
 *
 *  LEJPCB_ARRAY_END:   An array ended
 *
 *  LEJPCB_OBJECT_START: An object started
 *
 *  LEJPCB_OBJECT_END:  An object ended
 */
LWS_EXTERN signed char _lejp_callback(struct lejp_ctx *ctx, char reason);
 
typedef signed char (*lejp_callback)(struct lejp_ctx *ctx, char reason);
 
#ifndef LEJP_MAX_PARSING_STACK_DEPTH
#define LEJP_MAX_PARSING_STACK_DEPTH 8
#endif
#ifndef LEJP_MAX_DEPTH
#define LEJP_MAX_DEPTH 16
#endif
#ifndef LEJP_MAX_INDEX_DEPTH
#define LEJP_MAX_INDEX_DEPTH 12
#endif
#ifndef LEJP_MAX_PATH
#define LEJP_MAX_PATH 192
#endif
#ifndef LEJP_STRING_CHUNK
/* must be >= 30 to assemble floats */
#define LEJP_STRING_CHUNK 254
#endif
 
enum num_flags {
        LEJP_SEEN_MINUS         = (1 << 0),
        LEJP_SEEN_POINT         = (1 << 1),
        LEJP_SEEN_POST_POINT    = (1 << 2),
        LEJP_SEEN_EXP           = (1 << 3)
};
 
struct _lejp_stack {
        char                    s; /* lejp_state stack*/
        char                    p;      /* path length */
        char                    i; /* index array length */
        char                    b; /* user bitfield */
};
 
struct _lejp_parsing_stack {
        void                    *user;  /* private to the stack level */
        signed char             (*callback)(struct lejp_ctx *ctx, char reason);
        const char * const      *paths;
        uint8_t                 count_paths;
        uint8_t                 ppos;
        uint8_t                 path_match;
};
 
struct lejp_ctx {
 
        /* sorted by type for most compact alignment
         *
         * pointers
         */
        void *user;
 
        /* arrays */
 
        struct _lejp_parsing_stack pst[LEJP_MAX_PARSING_STACK_DEPTH];
        struct _lejp_stack st[LEJP_MAX_DEPTH];
        uint16_t i[LEJP_MAX_INDEX_DEPTH]; /* index array */
        uint16_t wild[LEJP_MAX_INDEX_DEPTH]; /* index array */
        char path[LEJP_MAX_PATH];
        char buf[LEJP_STRING_CHUNK + 1];
 
        /* size_t */
 
        size_t path_stride; /* 0 means default ptr size, else stride */
 
        /* int */
 
        uint32_t line;
 
        /* short */
 
        uint16_t uni;
#define LEJP_FLAG_FEAT_OBJECT_INDEXES                           (1 << 0)
#define LEJP_FLAG_FEAT_LEADING_WC                               (1 << 1)
#define LEJP_FLAG_LATEST
                                        (LEJP_FLAG_FEAT_OBJECT_INDEXES |
                                         LEJP_FLAG_FEAT_LEADING_WC)
        uint16_t flags;
 
        /* char */
 
        uint8_t npos;
        uint8_t dcount;
        uint8_t f;
        uint8_t sp; /* stack head */
        uint8_t ipos; /* index stack depth */
        uint8_t count_paths;
        uint8_t path_match;
        uint8_t path_match_len;
        uint8_t wildcount;
        uint8_t pst_sp; /* parsing stack head */
        uint8_t outer_array;
};
 
LWS_VISIBLE LWS_EXTERN void
lejp_construct(struct lejp_ctx *ctx,
               signed char (*callback)(struct lejp_ctx *ctx, char reason),
               void *user, const char * const *paths, unsigned char paths_count);
 
LWS_VISIBLE LWS_EXTERN void
lejp_destruct(struct lejp_ctx *ctx);
 
LWS_VISIBLE LWS_EXTERN int
lejp_parse(struct lejp_ctx *ctx, const unsigned char *json, int len);
 
LWS_VISIBLE LWS_EXTERN void
lejp_change_callback(struct lejp_ctx *ctx,
                     signed char (*callback)(struct lejp_ctx *ctx, char reason));
 
/*
 * push the current paths / paths_count and lejp_cb to a stack in the ctx, and
 * start using the new ones
 */
LWS_VISIBLE LWS_EXTERN int
lejp_parser_push(struct lejp_ctx *ctx, void *user, const char * const *paths,
                 unsigned char paths_count, lejp_callback lejp_cb);
 
/*
 * pop the previously used paths / paths_count and lejp_cb, and continue
 * parsing using those as before
 */
LWS_VISIBLE LWS_EXTERN int
lejp_parser_pop(struct lejp_ctx *ctx);
 
/* exported for use when reevaluating a path for use with a subcontext */
LWS_VISIBLE LWS_EXTERN void
lejp_check_path_match(struct lejp_ctx *ctx);
 
LWS_VISIBLE LWS_EXTERN int
lejp_get_wildcard(struct lejp_ctx *ctx, int wildcard, char *dest, int len);
 
LWS_VISIBLE LWS_EXTERN const char *
lejp_error_to_string(int e);
//@}