aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/core/lib/json/json_string.c
blob: 4af7ee7179c1b44a081b1fd40f8e89fe3bc3051e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <stdlib.h>
#include <string.h>

#include <grpc/support/alloc.h>
#include <grpc/support/log.h>

#include "src/core/lib/json/json.h"
#include "src/core/lib/json/json_reader.h"
#include "src/core/lib/json/json_writer.h"

/* The json reader will construct a bunch of grpc_json objects and
 * link them all up together in a tree-like structure that will represent
 * the json data in memory.
 *
 * It also uses its own input as a scratchpad to store all of the decoded,
 * unescaped strings. So we need to keep track of all these pointers in
 * that opaque structure the reader will carry for us.
 *
 * Note that this works because the act of parsing json always reduces its
 * input size, and never expands it.
 */
typedef struct {
  grpc_json *top;
  grpc_json *current_container;
  grpc_json *current_value;
  uint8_t *input;
  uint8_t *key;
  uint8_t *string;
  uint8_t *string_ptr;
  size_t remaining_input;
} json_reader_userdata;

/* This json writer will put everything in a big string.
 * The point is that we allocate that string in chunks of 256 bytes.
 */
typedef struct {
  char *output;
  size_t free_space;
  size_t string_len;
  size_t allocated;
} json_writer_userdata;

/* This function checks if there's enough space left in the output buffer,
 * and will enlarge it if necessary. We're only allocating chunks of 256
 * bytes at a time (or multiples thereof).
 */
static void json_writer_output_check(void *userdata, size_t needed) {
  json_writer_userdata *state = userdata;
  if (state->free_space >= needed) return;
  needed -= state->free_space;
  /* Round up by 256 bytes. */
  needed = (needed + 0xff) & ~0xffU;
  state->output = gpr_realloc(state->output, state->allocated + needed);
  state->free_space += needed;
  state->allocated += needed;
}

/* These are needed by the writer's implementation. */
static void json_writer_output_char(void *userdata, char c) {
  json_writer_userdata *state = userdata;
  json_writer_output_check(userdata, 1);
  state->output[state->string_len++] = c;
  state->free_space--;
}

static void json_writer_output_string_with_len(void *userdata, const char *str,
                                               size_t len) {
  json_writer_userdata *state = userdata;
  json_writer_output_check(userdata, len);
  memcpy(state->output + state->string_len, str, len);
  state->string_len += len;
  state->free_space -= len;
}

static void json_writer_output_string(void *userdata, const char *str) {
  size_t len = strlen(str);
  json_writer_output_string_with_len(userdata, str, len);
}

/* The reader asks us to clear our scratchpad. In our case, we'll simply mark
 * the end of the current string, and advance our output pointer.
 */
static void json_reader_string_clear(void *userdata) {
  json_reader_userdata *state = userdata;
  if (state->string) {
    GPR_ASSERT(state->string_ptr < state->input);
    *state->string_ptr++ = 0;
  }
  state->string = state->string_ptr;
}

static void json_reader_string_add_char(void *userdata, uint32_t c) {
  json_reader_userdata *state = userdata;
  GPR_ASSERT(state->string_ptr < state->input);
  GPR_ASSERT(c <= 0xff);
  *state->string_ptr++ = (uint8_t)c;
}

/* We are converting a UTF-32 character into UTF-8 here,
 * as described by RFC3629.
 */
static void json_reader_string_add_utf32(void *userdata, uint32_t c) {
  if (c <= 0x7f) {
    json_reader_string_add_char(userdata, c);
  } else if (c <= 0x7ff) {
    uint32_t b1 = 0xc0 | ((c >> 6) & 0x1f);
    uint32_t b2 = 0x80 | (c & 0x3f);
    json_reader_string_add_char(userdata, b1);
    json_reader_string_add_char(userdata, b2);
  } else if (c <= 0xffff) {
    uint32_t b1 = 0xe0 | ((c >> 12) & 0x0f);
    uint32_t b2 = 0x80 | ((c >> 6) & 0x3f);
    uint32_t b3 = 0x80 | (c & 0x3f);
    json_reader_string_add_char(userdata, b1);
    json_reader_string_add_char(userdata, b2);
    json_reader_string_add_char(userdata, b3);
  } else if (c <= 0x1fffff) {
    uint32_t b1 = 0xf0 | ((c >> 18) & 0x07);
    uint32_t b2 = 0x80 | ((c >> 12) & 0x3f);
    uint32_t b3 = 0x80 | ((c >> 6) & 0x3f);
    uint32_t b4 = 0x80 | (c & 0x3f);
    json_reader_string_add_char(userdata, b1);
    json_reader_string_add_char(userdata, b2);
    json_reader_string_add_char(userdata, b3);
    json_reader_string_add_char(userdata, b4);
  }
}

/* We consider that the input may be a zero-terminated string. So we
 * can end up hitting eof before the end of the alleged string length.
 */
static uint32_t json_reader_read_char(void *userdata) {
  uint32_t r;
  json_reader_userdata *state = userdata;

  if (state->remaining_input == 0) return GRPC_JSON_READ_CHAR_EOF;

  r = *state->input++;
  state->remaining_input--;

  if (r == 0) {
    state->remaining_input = 0;
    return GRPC_JSON_READ_CHAR_EOF;
  }

  return r;
}

/* Helper function to create a new grpc_json object and link it into
 * our tree-in-progress inside our opaque structure.
 */
static grpc_json *json_create_and_link(void *userdata, grpc_json_type type) {
  json_reader_userdata *state = userdata;
  grpc_json *json = grpc_json_create(type);

  json->parent = state->current_container;
  json->prev = state->current_value;
  state->current_value = json;

  if (json->prev) {
    json->prev->next = json;
  }
  if (json->parent) {
    if (!json->parent->child) {
      json->parent->child = json;
    }
    if (json->parent->type == GRPC_JSON_OBJECT) {
      json->key = (char *)state->key;
    }
  }
  if (!state->top) {
    state->top = json;
  }

  return json;
}

static void json_reader_container_begins(void *userdata, grpc_json_type type) {
  json_reader_userdata *state = userdata;
  grpc_json *container;

  GPR_ASSERT(type == GRPC_JSON_ARRAY || type == GRPC_JSON_OBJECT);

  container = json_create_and_link(userdata, type);
  state->current_container = container;
  state->current_value = NULL;
}

/* It's important to remember that the reader is mostly stateless, so it
 * isn't trying to remember what the container was prior the one that just
 * ends. Since we're keeping track of these for our own purpose, we are
 * able to return that information back, which is useful for it to validate
 * the input json stream.
 *
 * Also note that if we're at the top of the tree, and the last container
 * ends, we have to return GRPC_JSON_TOP_LEVEL.
 */
static grpc_json_type json_reader_container_ends(void *userdata) {
  grpc_json_type container_type = GRPC_JSON_TOP_LEVEL;
  json_reader_userdata *state = userdata;

  GPR_ASSERT(state->current_container);

  state->current_value = state->current_container;
  state->current_container = state->current_container->parent;

  if (state->current_container) {
    container_type = state->current_container->type;
  }

  return container_type;
}

/* The next 3 functions basically are the reader asking us to use our string
 * scratchpad for one of these 3 purposes.
 *
 * Note that in the set_number case, we're not going to try interpreting it.
 * We'll keep it as a string, and leave it to the caller to evaluate it.
 */
static void json_reader_set_key(void *userdata) {
  json_reader_userdata *state = userdata;
  state->key = state->string;
}

static void json_reader_set_string(void *userdata) {
  json_reader_userdata *state = userdata;
  grpc_json *json = json_create_and_link(userdata, GRPC_JSON_STRING);
  json->value = (char *)state->string;
}

static int json_reader_set_number(void *userdata) {
  json_reader_userdata *state = userdata;
  grpc_json *json = json_create_and_link(userdata, GRPC_JSON_NUMBER);
  json->value = (char *)state->string;
  return 1;
}

/* The object types true, false and null are self-sufficient, and don't need
 * any more information beside their type.
 */
static void json_reader_set_true(void *userdata) {
  json_create_and_link(userdata, GRPC_JSON_TRUE);
}

static void json_reader_set_false(void *userdata) {
  json_create_and_link(userdata, GRPC_JSON_FALSE);
}

static void json_reader_set_null(void *userdata) {
  json_create_and_link(userdata, GRPC_JSON_NULL);
}

static grpc_json_reader_vtable reader_vtable = {
    json_reader_string_clear,     json_reader_string_add_char,
    json_reader_string_add_utf32, json_reader_read_char,
    json_reader_container_begins, json_reader_container_ends,
    json_reader_set_key,          json_reader_set_string,
    json_reader_set_number,       json_reader_set_true,
    json_reader_set_false,        json_reader_set_null};

/* And finally, let's define our public API. */
grpc_json *grpc_json_parse_string_with_len(char *input, size_t size) {
  grpc_json_reader reader;
  json_reader_userdata state;
  grpc_json *json = NULL;
  grpc_json_reader_status status;

  if (!input) return NULL;

  state.top = state.current_container = state.current_value = NULL;
  state.string = state.key = NULL;
  state.string_ptr = state.input = (uint8_t *)input;
  state.remaining_input = size;
  grpc_json_reader_init(&reader, &reader_vtable, &state);

  status = grpc_json_reader_run(&reader);
  json = state.top;

  if ((status != GRPC_JSON_DONE) && json) {
    grpc_json_destroy(json);
    json = NULL;
  }

  return json;
}

#define UNBOUND_JSON_STRING_LENGTH 0x7fffffff

grpc_json *grpc_json_parse_string(char *input) {
  return grpc_json_parse_string_with_len(input, UNBOUND_JSON_STRING_LENGTH);
}

static void json_dump_recursive(grpc_json_writer *writer, grpc_json *json,
                                int in_object) {
  while (json) {
    if (in_object) grpc_json_writer_object_key(writer, json->key);

    switch (json->type) {
      case GRPC_JSON_OBJECT:
      case GRPC_JSON_ARRAY:
        grpc_json_writer_container_begins(writer, json->type);
        if (json->child)
          json_dump_recursive(writer, json->child,
                              json->type == GRPC_JSON_OBJECT);
        grpc_json_writer_container_ends(writer, json->type);
        break;
      case GRPC_JSON_STRING:
        grpc_json_writer_value_string(writer, json->value);
        break;
      case GRPC_JSON_NUMBER:
        grpc_json_writer_value_raw(writer, json->value);
        break;
      case GRPC_JSON_TRUE:
        grpc_json_writer_value_raw_with_len(writer, "true", 4);
        break;
      case GRPC_JSON_FALSE:
        grpc_json_writer_value_raw_with_len(writer, "false", 5);
        break;
      case GRPC_JSON_NULL:
        grpc_json_writer_value_raw_with_len(writer, "null", 4);
        break;
      default:
        GPR_UNREACHABLE_CODE(abort());
    }
    json = json->next;
  }
}

static grpc_json_writer_vtable writer_vtable = {
    json_writer_output_char, json_writer_output_string,
    json_writer_output_string_with_len};

char *grpc_json_dump_to_string(grpc_json *json, int indent) {
  grpc_json_writer writer;
  json_writer_userdata state;

  state.output = NULL;
  state.free_space = state.string_len = state.allocated = 0;
  grpc_json_writer_init(&writer, indent, &writer_vtable, &state);

  json_dump_recursive(&writer, json, 0);

  json_writer_output_char(&state, 0);

  return state.output;
}