1/*
2 * libwebsockets - small server side websockets and web server implementation
3 *
4 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22 * IN THE SOFTWARE.
23 */
24
25/** \defgroup lejp JSON parser
26 * ##JSON parsing related functions
27 * \ingroup lwsapi
28 *
29 * LEJP is an extremely lightweight JSON stream parser included in lws.
30 */
31//@{
32struct lejp_ctx;
33
34#if !defined(LWS_ARRAY_SIZE)
35#define LWS_ARRAY_SIZE(_x) (sizeof(_x) / sizeof(_x[0]))
36#endif
37#define LEJP_FLAG_WS_KEEP 64
38#define LEJP_FLAG_WS_COMMENTLINE 32
39
40enum lejp_states {
41 LEJP_IDLE = 0,
42 LEJP_MEMBERS = 1,
43 LEJP_M_P = 2,
44 LEJP_MP_STRING = LEJP_FLAG_WS_KEEP | 3,
45 LEJP_MP_STRING_ESC = LEJP_FLAG_WS_KEEP | 4,
46 LEJP_MP_STRING_ESC_U1 = LEJP_FLAG_WS_KEEP | 5,
47 LEJP_MP_STRING_ESC_U2 = LEJP_FLAG_WS_KEEP | 6,
48 LEJP_MP_STRING_ESC_U3 = LEJP_FLAG_WS_KEEP | 7,
49 LEJP_MP_STRING_ESC_U4 = LEJP_FLAG_WS_KEEP | 8,
50 LEJP_MP_DELIM = 9,
51 LEJP_MP_VALUE = 10,
52 LEJP_MP_VALUE_NUM_INT = LEJP_FLAG_WS_KEEP | 11,
53 LEJP_MP_VALUE_NUM_EXP = LEJP_FLAG_WS_KEEP | 12,
54 LEJP_MP_VALUE_TOK = LEJP_FLAG_WS_KEEP | 13,
55 LEJP_MP_COMMA_OR_END = 14,
56 LEJP_MP_ARRAY_END = 15,
57};
58
59enum lejp_reasons {
60 LEJP_CONTINUE = -1,
61 LEJP_REJECT_IDLE_NO_BRACE = -2,
62 LEJP_REJECT_MEMBERS_NO_CLOSE = -3,
63 LEJP_REJECT_MP_NO_OPEN_QUOTE = -4,
64 LEJP_REJECT_MP_STRING_UNDERRUN = -5,
65 LEJP_REJECT_MP_ILLEGAL_CTRL = -6,
66 LEJP_REJECT_MP_STRING_ESC_ILLEGAL_ESC = -7,
67 LEJP_REJECT_ILLEGAL_HEX = -8,
68 LEJP_REJECT_MP_DELIM_MISSING_COLON = -9,
69 LEJP_REJECT_MP_DELIM_BAD_VALUE_START = -10,
70 LEJP_REJECT_MP_VAL_NUM_INT_NO_FRAC = -11,
71 LEJP_REJECT_MP_VAL_NUM_FORMAT = -12,
72 LEJP_REJECT_MP_VAL_NUM_EXP_BAD_EXP = -13,
73 LEJP_REJECT_MP_VAL_TOK_UNKNOWN = -14,
74 LEJP_REJECT_MP_C_OR_E_UNDERF = -15,
75 LEJP_REJECT_MP_C_OR_E_NOTARRAY = -16,
76 LEJP_REJECT_MP_ARRAY_END_MISSING = -17,
77 LEJP_REJECT_STACK_OVERFLOW = -18,
78 LEJP_REJECT_MP_DELIM_ISTACK = -19,
79 LEJP_REJECT_NUM_TOO_LONG = -20,
80 LEJP_REJECT_MP_C_OR_E_NEITHER = -21,
81 LEJP_REJECT_UNKNOWN = -22,
82 LEJP_REJECT_CALLBACK = -23
83};
84
85#define LEJP_FLAG_CB_IS_VALUE 64
86
87enum lejp_callbacks {
88 LEJPCB_CONSTRUCTED = 0,
89 LEJPCB_DESTRUCTED = 1,
90
91 LEJPCB_START = 2,
92 LEJPCB_COMPLETE = 3,
93 LEJPCB_FAILED = 4,
94
95 LEJPCB_PAIR_NAME = 5,
96
97 LEJPCB_VAL_TRUE = LEJP_FLAG_CB_IS_VALUE | 6,
98 LEJPCB_VAL_FALSE = LEJP_FLAG_CB_IS_VALUE | 7,
99 LEJPCB_VAL_NULL = LEJP_FLAG_CB_IS_VALUE | 8,
100 LEJPCB_VAL_NUM_INT = LEJP_FLAG_CB_IS_VALUE | 9,
101 LEJPCB_VAL_NUM_FLOAT = LEJP_FLAG_CB_IS_VALUE | 10,
102 LEJPCB_VAL_STR_START = 11, /* notice handle separately */
103 LEJPCB_VAL_STR_CHUNK = LEJP_FLAG_CB_IS_VALUE | 12,
104 LEJPCB_VAL_STR_END = LEJP_FLAG_CB_IS_VALUE | 13,
105
106 LEJPCB_ARRAY_START = 14,
107 LEJPCB_ARRAY_END = 15,
108
109 LEJPCB_OBJECT_START = 16,
110 LEJPCB_OBJECT_END = 17,
111
112 LEJPCB_USER_START = 32,
113};
114
115/**
116 * _lejp_callback() - User parser actions
117 * \param ctx: LEJP context
118 * \param reason: Callback reason
119 *
120 * Your user callback is associated with the context at construction time,
121 * and receives calls as the parsing progresses.
122 *
123 * All of the callbacks may be ignored and just return 0.
124 *
125 * The reasons it might get called, found in @reason, are:
126 *
127 * LEJPCB_CONSTRUCTED: The context was just constructed... you might want to
128 * perform one-time allocation for the life of the context.
129 *
130 * LEJPCB_DESTRUCTED: The context is being destructed... if you made any
131 * allocations at construction-time, you can free them now
132 *
133 * LEJPCB_START: Parsing is beginning at the first byte of input
134 *
135 * LEJPCB_COMPLETE: Parsing has completed successfully. You'll get a 0 or
136 * positive return code from lejp_parse indicating the
137 * amount of unused bytes left in the input buffer
138 *
139 * LEJPCB_FAILED: Parsing failed. You'll get a negative error code
140 * returned from lejp_parse
141 *
142 * LEJPCB_PAIR_NAME: When a "name":"value" pair has had the name parsed,
143 * this callback occurs. You can find the new name at
144 * the end of ctx->path[]
145 *
146 * LEJPCB_VAL_TRUE: The "true" value appeared
147 *
148 * LEJPCB_VAL_FALSE: The "false" value appeared
149 *
150 * LEJPCB_VAL_NULL: The "null" value appeared
151 *
152 * LEJPCB_VAL_NUM_INT: A string representing an integer is in ctx->buf
153 *
154 * LEJPCB_VAL_NUM_FLOAT: A string representing a float is in ctx->buf
155 *
156 * LEJPCB_VAL_STR_START: We are starting to parse a string, no data yet
157 *
158 * LEJPCB_VAL_STR_CHUNK: We filled the string buffer in the ctx, but it's not
159 * the end of the string. We produce this to spill the
160 * intermediate buffer to the user code, so we can handle
161 * huge JSON strings using only the small buffer in the
162 * ctx. If the whole JSON string fits in the ctx buffer,
163 * you won't get these callbacks.
164 *
165 * LEJPCB_VAL_STR_END: String parsing has completed, the last chunk of the
166 * string is in ctx->buf.
167 *
168 * LEJPCB_ARRAY_START: An array started
169 *
170 * LEJPCB_ARRAY_END: An array ended
171 *
172 * LEJPCB_OBJECT_START: An object started
173 *
174 * LEJPCB_OBJECT_END: An object ended
175 */
176LWS_EXTERN signed char _lejp_callback(struct lejp_ctx *ctx, char reason);
177
178typedef signed char (*lejp_callback)(struct lejp_ctx *ctx, char reason);
179
180#ifndef LEJP_MAX_PARSING_STACK_DEPTH
181#define LEJP_MAX_PARSING_STACK_DEPTH 8
182#endif
183#ifndef LEJP_MAX_DEPTH
184#define LEJP_MAX_DEPTH 16
185#endif
186#ifndef LEJP_MAX_INDEX_DEPTH
187#define LEJP_MAX_INDEX_DEPTH 12
188#endif
189#ifndef LEJP_MAX_PATH
190#define LEJP_MAX_PATH 192
191#endif
192#ifndef LEJP_STRING_CHUNK
193/* must be >= 30 to assemble floats */
194#define LEJP_STRING_CHUNK 254
195#endif
196
197enum num_flags {
198 LEJP_SEEN_MINUS = (1 << 0),
199 LEJP_SEEN_POINT = (1 << 1),
200 LEJP_SEEN_POST_POINT = (1 << 2),
201 LEJP_SEEN_EXP = (1 << 3)
202};
203
204struct _lejp_stack {
205 char s; /* lejp_state stack*/
206 char p; /* path length */
207 char i; /* index array length */
208 char b; /* user bitfield */
209};
210
211struct _lejp_parsing_stack {
212 void *user; /* private to the stack level */
213 signed char (*callback)(struct lejp_ctx *ctx, char reason);
214 const char * const *paths;
215 uint8_t count_paths;
216 uint8_t ppos;
217 uint8_t path_match;
218};
219
220struct lejp_ctx {
221
222 /* sorted by type for most compact alignment
223 *
224 * pointers
225 */
226 void *user;
227
228 /* arrays */
229
230 struct _lejp_parsing_stack pst[LEJP_MAX_PARSING_STACK_DEPTH];
231 struct _lejp_stack st[LEJP_MAX_DEPTH];
232 uint16_t i[LEJP_MAX_INDEX_DEPTH]; /* index array */
233 uint16_t wild[LEJP_MAX_INDEX_DEPTH]; /* index array */
234 char path[LEJP_MAX_PATH];
235 char buf[LEJP_STRING_CHUNK + 1];
236
237 /* size_t */
238
239 size_t path_stride; /* 0 means default ptr size, else stride */
240
241 /* int */
242
243 uint32_t line;
244
245 /* short */
246
247 uint16_t uni;
248#define LEJP_FLAG_FEAT_OBJECT_INDEXES (1 << 0)
249#define LEJP_FLAG_FEAT_LEADING_WC (1 << 1)
250#define LEJP_FLAG_LATEST \
251 (LEJP_FLAG_FEAT_OBJECT_INDEXES | \
252 LEJP_FLAG_FEAT_LEADING_WC)
253 uint16_t flags;
254
255 /* char */
256
257 uint8_t npos;
258 uint8_t dcount;
259 uint8_t f;
260 uint8_t sp; /* stack head */
261 uint8_t ipos; /* index stack depth */
262 uint8_t count_paths;
263 uint8_t path_match;
264 uint8_t path_match_len;
265 uint8_t wildcount;
266 uint8_t pst_sp; /* parsing stack head */
267 uint8_t outer_array;
268};
269
270LWS_VISIBLE LWS_EXTERN void
271lejp_construct(struct lejp_ctx *ctx,
272 signed char (*callback)(struct lejp_ctx *ctx, char reason),
273 void *user, const char * const *paths, unsigned char paths_count);
274
275LWS_VISIBLE LWS_EXTERN void
276lejp_destruct(struct lejp_ctx *ctx);
277
278LWS_VISIBLE LWS_EXTERN int
279lejp_parse(struct lejp_ctx *ctx, const unsigned char *json, int len);
280
281LWS_VISIBLE LWS_EXTERN void
282lejp_change_callback(struct lejp_ctx *ctx,
283 signed char (*callback)(struct lejp_ctx *ctx, char reason));
284
285/*
286 * push the current paths / paths_count and lejp_cb to a stack in the ctx, and
287 * start using the new ones
288 */
289LWS_VISIBLE LWS_EXTERN int
290lejp_parser_push(struct lejp_ctx *ctx, void *user, const char * const *paths,
291 unsigned char paths_count, lejp_callback lejp_cb);
292
293/*
294 * pop the previously used paths / paths_count and lejp_cb, and continue
295 * parsing using those as before
296 */
297LWS_VISIBLE LWS_EXTERN int
298lejp_parser_pop(struct lejp_ctx *ctx);
299
300/* exported for use when reevaluating a path for use with a subcontext */
301LWS_VISIBLE LWS_EXTERN void
302lejp_check_path_match(struct lejp_ctx *ctx);
303
304LWS_VISIBLE LWS_EXTERN int
305lejp_get_wildcard(struct lejp_ctx *ctx, int wildcard, char *dest, int len);
306
307LWS_VISIBLE LWS_EXTERN const char *
308lejp_error_to_string(int e);
309//@}
310