1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #include <grpc/support/port_platform.h>
20
21 #include <stdlib.h>
22 #include <string.h>
23
24 #include <grpc/support/alloc.h>
25 #include <grpc/support/log.h>
26
27 #include "src/core/lib/json/json.h"
28 #include "src/core/lib/json/json_reader.h"
29 #include "src/core/lib/json/json_writer.h"
30
31 /* The json reader will construct a bunch of grpc_json objects and
32 * link them all up together in a tree-like structure that will represent
33 * the json data in memory.
34 *
35 * It also uses its own input as a scratchpad to store all of the decoded,
36 * unescaped strings. So we need to keep track of all these pointers in
37 * that opaque structure the reader will carry for us.
38 *
39 * Note that this works because the act of parsing json always reduces its
40 * input size, and never expands it.
41 */
42 typedef struct {
43 grpc_json* top;
44 grpc_json* current_container;
45 grpc_json* current_value;
46 uint8_t* input;
47 uint8_t* key;
48 uint8_t* string;
49 uint8_t* string_ptr;
50 size_t remaining_input;
51 } json_reader_userdata;
52
53 /* This json writer will put everything in a big string.
54 * The point is that we allocate that string in chunks of 256 bytes.
55 */
56 typedef struct {
57 char* output;
58 size_t free_space;
59 size_t string_len;
60 size_t allocated;
61 } json_writer_userdata;
62
63 /* This function checks if there's enough space left in the output buffer,
64 * and will enlarge it if necessary. We're only allocating chunks of 256
65 * bytes at a time (or multiples thereof).
66 */
json_writer_output_check(void * userdata,size_t needed)67 static void json_writer_output_check(void* userdata, size_t needed) {
68 json_writer_userdata* state = static_cast<json_writer_userdata*>(userdata);
69 if (state->free_space >= needed) return;
70 needed -= state->free_space;
71 /* Round up by 256 bytes. */
72 needed = (needed + 0xff) & ~0xffU;
73 state->output =
74 static_cast<char*>(gpr_realloc(state->output, state->allocated + needed));
75 state->free_space += needed;
76 state->allocated += needed;
77 }
78
79 /* These are needed by the writer's implementation. */
json_writer_output_char(void * userdata,char c)80 static void json_writer_output_char(void* userdata, char c) {
81 json_writer_userdata* state = static_cast<json_writer_userdata*>(userdata);
82 json_writer_output_check(userdata, 1);
83 state->output[state->string_len++] = c;
84 state->free_space--;
85 }
86
json_writer_output_string_with_len(void * userdata,const char * str,size_t len)87 static void json_writer_output_string_with_len(void* userdata, const char* str,
88 size_t len) {
89 json_writer_userdata* state = static_cast<json_writer_userdata*>(userdata);
90 json_writer_output_check(userdata, len);
91 memcpy(state->output + state->string_len, str, len);
92 state->string_len += len;
93 state->free_space -= len;
94 }
95
json_writer_output_string(void * userdata,const char * str)96 static void json_writer_output_string(void* userdata, const char* str) {
97 size_t len = strlen(str);
98 json_writer_output_string_with_len(userdata, str, len);
99 }
100
101 /* The reader asks us to clear our scratchpad. In our case, we'll simply mark
102 * the end of the current string, and advance our output pointer.
103 */
json_reader_string_clear(void * userdata)104 static void json_reader_string_clear(void* userdata) {
105 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
106 if (state->string) {
107 GPR_ASSERT(state->string_ptr < state->input);
108 *state->string_ptr++ = 0;
109 }
110 state->string = state->string_ptr;
111 }
112
json_reader_string_add_char(void * userdata,uint32_t c)113 static void json_reader_string_add_char(void* userdata, uint32_t c) {
114 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
115 GPR_ASSERT(state->string_ptr < state->input);
116 GPR_ASSERT(c <= 0xff);
117 *state->string_ptr++ = static_cast<uint8_t>(c);
118 }
119
120 /* We are converting a UTF-32 character into UTF-8 here,
121 * as described by RFC3629.
122 */
json_reader_string_add_utf32(void * userdata,uint32_t c)123 static void json_reader_string_add_utf32(void* userdata, uint32_t c) {
124 if (c <= 0x7f) {
125 json_reader_string_add_char(userdata, c);
126 } else if (c <= 0x7ff) {
127 uint32_t b1 = 0xc0 | ((c >> 6) & 0x1f);
128 uint32_t b2 = 0x80 | (c & 0x3f);
129 json_reader_string_add_char(userdata, b1);
130 json_reader_string_add_char(userdata, b2);
131 } else if (c <= 0xffff) {
132 uint32_t b1 = 0xe0 | ((c >> 12) & 0x0f);
133 uint32_t b2 = 0x80 | ((c >> 6) & 0x3f);
134 uint32_t b3 = 0x80 | (c & 0x3f);
135 json_reader_string_add_char(userdata, b1);
136 json_reader_string_add_char(userdata, b2);
137 json_reader_string_add_char(userdata, b3);
138 } else if (c <= 0x1fffff) {
139 uint32_t b1 = 0xf0 | ((c >> 18) & 0x07);
140 uint32_t b2 = 0x80 | ((c >> 12) & 0x3f);
141 uint32_t b3 = 0x80 | ((c >> 6) & 0x3f);
142 uint32_t b4 = 0x80 | (c & 0x3f);
143 json_reader_string_add_char(userdata, b1);
144 json_reader_string_add_char(userdata, b2);
145 json_reader_string_add_char(userdata, b3);
146 json_reader_string_add_char(userdata, b4);
147 }
148 }
149
150 /* We consider that the input may be a zero-terminated string. So we
151 * can end up hitting eof before the end of the alleged string length.
152 */
json_reader_read_char(void * userdata)153 static uint32_t json_reader_read_char(void* userdata) {
154 uint32_t r;
155 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
156
157 if (state->remaining_input == 0) return GRPC_JSON_READ_CHAR_EOF;
158
159 r = *state->input++;
160 state->remaining_input--;
161
162 if (r == 0) {
163 state->remaining_input = 0;
164 return GRPC_JSON_READ_CHAR_EOF;
165 }
166
167 return r;
168 }
169
170 /* Helper function to create a new grpc_json object and link it into
171 * our tree-in-progress inside our opaque structure.
172 */
json_create_and_link(void * userdata,grpc_json_type type)173 static grpc_json* json_create_and_link(void* userdata, grpc_json_type type) {
174 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
175 grpc_json* json = grpc_json_create(type);
176
177 json->parent = state->current_container;
178 json->prev = state->current_value;
179 state->current_value = json;
180
181 if (json->prev) {
182 json->prev->next = json;
183 }
184 if (json->parent) {
185 if (!json->parent->child) {
186 json->parent->child = json;
187 }
188 if (json->parent->type == GRPC_JSON_OBJECT) {
189 json->key = reinterpret_cast<char*>(state->key);
190 }
191 }
192 if (!state->top) {
193 state->top = json;
194 }
195
196 return json;
197 }
198
json_reader_container_begins(void * userdata,grpc_json_type type)199 static void json_reader_container_begins(void* userdata, grpc_json_type type) {
200 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
201 grpc_json* container;
202
203 GPR_ASSERT(type == GRPC_JSON_ARRAY || type == GRPC_JSON_OBJECT);
204
205 container = json_create_and_link(userdata, type);
206 state->current_container = container;
207 state->current_value = nullptr;
208 }
209
210 /* It's important to remember that the reader is mostly stateless, so it
211 * isn't trying to remember what the container was prior the one that just
212 * ends. Since we're keeping track of these for our own purpose, we are
213 * able to return that information back, which is useful for it to validate
214 * the input json stream.
215 *
216 * Also note that if we're at the top of the tree, and the last container
217 * ends, we have to return GRPC_JSON_TOP_LEVEL.
218 */
json_reader_container_ends(void * userdata)219 static grpc_json_type json_reader_container_ends(void* userdata) {
220 grpc_json_type container_type = GRPC_JSON_TOP_LEVEL;
221 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
222
223 GPR_ASSERT(state->current_container);
224
225 state->current_value = state->current_container;
226 state->current_container = state->current_container->parent;
227
228 if (state->current_container) {
229 container_type = state->current_container->type;
230 }
231
232 return container_type;
233 }
234
235 /* The next 3 functions basically are the reader asking us to use our string
236 * scratchpad for one of these 3 purposes.
237 *
238 * Note that in the set_number case, we're not going to try interpreting it.
239 * We'll keep it as a string, and leave it to the caller to evaluate it.
240 */
json_reader_set_key(void * userdata)241 static void json_reader_set_key(void* userdata) {
242 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
243 state->key = state->string;
244 }
245
json_reader_set_string(void * userdata)246 static void json_reader_set_string(void* userdata) {
247 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
248 grpc_json* json = json_create_and_link(userdata, GRPC_JSON_STRING);
249 json->value = reinterpret_cast<char*>(state->string);
250 }
251
json_reader_set_number(void * userdata)252 static int json_reader_set_number(void* userdata) {
253 json_reader_userdata* state = static_cast<json_reader_userdata*>(userdata);
254 grpc_json* json = json_create_and_link(userdata, GRPC_JSON_NUMBER);
255 json->value = reinterpret_cast<char*>(state->string);
256 return 1;
257 }
258
259 /* The object types true, false and null are self-sufficient, and don't need
260 * any more information beside their type.
261 */
json_reader_set_true(void * userdata)262 static void json_reader_set_true(void* userdata) {
263 json_create_and_link(userdata, GRPC_JSON_TRUE);
264 }
265
json_reader_set_false(void * userdata)266 static void json_reader_set_false(void* userdata) {
267 json_create_and_link(userdata, GRPC_JSON_FALSE);
268 }
269
json_reader_set_null(void * userdata)270 static void json_reader_set_null(void* userdata) {
271 json_create_and_link(userdata, GRPC_JSON_NULL);
272 }
273
274 static grpc_json_reader_vtable reader_vtable = {
275 json_reader_string_clear, json_reader_string_add_char,
276 json_reader_string_add_utf32, json_reader_read_char,
277 json_reader_container_begins, json_reader_container_ends,
278 json_reader_set_key, json_reader_set_string,
279 json_reader_set_number, json_reader_set_true,
280 json_reader_set_false, json_reader_set_null};
281
282 /* And finally, let's define our public API. */
grpc_json_parse_string_with_len(char * input,size_t size)283 grpc_json* grpc_json_parse_string_with_len(char* input, size_t size) {
284 grpc_json_reader reader;
285 json_reader_userdata state;
286 grpc_json* json = nullptr;
287 grpc_json_reader_status status;
288
289 if (!input) return nullptr;
290
291 state.top = state.current_container = state.current_value = nullptr;
292 state.string = state.key = nullptr;
293 state.string_ptr = state.input = reinterpret_cast<uint8_t*>(input);
294 state.remaining_input = size;
295 grpc_json_reader_init(&reader, &reader_vtable, &state);
296
297 status = grpc_json_reader_run(&reader);
298 json = state.top;
299
300 if ((status != GRPC_JSON_DONE) && json) {
301 grpc_json_destroy(json);
302 json = nullptr;
303 }
304
305 return json;
306 }
307
308 #define UNBOUND_JSON_STRING_LENGTH 0x7fffffff
309
grpc_json_parse_string(char * input)310 grpc_json* grpc_json_parse_string(char* input) {
311 return grpc_json_parse_string_with_len(input, UNBOUND_JSON_STRING_LENGTH);
312 }
313
json_dump_recursive(grpc_json_writer * writer,grpc_json * json,int in_object)314 static void json_dump_recursive(grpc_json_writer* writer, grpc_json* json,
315 int in_object) {
316 while (json) {
317 if (in_object) grpc_json_writer_object_key(writer, json->key);
318
319 switch (json->type) {
320 case GRPC_JSON_OBJECT:
321 case GRPC_JSON_ARRAY:
322 grpc_json_writer_container_begins(writer, json->type);
323 if (json->child)
324 json_dump_recursive(writer, json->child,
325 json->type == GRPC_JSON_OBJECT);
326 grpc_json_writer_container_ends(writer, json->type);
327 break;
328 case GRPC_JSON_STRING:
329 grpc_json_writer_value_string(writer, json->value);
330 break;
331 case GRPC_JSON_NUMBER:
332 grpc_json_writer_value_raw(writer, json->value);
333 break;
334 case GRPC_JSON_TRUE:
335 grpc_json_writer_value_raw_with_len(writer, "true", 4);
336 break;
337 case GRPC_JSON_FALSE:
338 grpc_json_writer_value_raw_with_len(writer, "false", 5);
339 break;
340 case GRPC_JSON_NULL:
341 grpc_json_writer_value_raw_with_len(writer, "null", 4);
342 break;
343 default:
344 GPR_UNREACHABLE_CODE(abort());
345 }
346 json = json->next;
347 }
348 }
349
350 static grpc_json_writer_vtable writer_vtable = {
351 json_writer_output_char, json_writer_output_string,
352 json_writer_output_string_with_len};
353
grpc_json_dump_to_string(grpc_json * json,int indent)354 char* grpc_json_dump_to_string(grpc_json* json, int indent) {
355 grpc_json_writer writer;
356 json_writer_userdata state;
357
358 state.output = nullptr;
359 state.free_space = state.string_len = state.allocated = 0;
360 grpc_json_writer_init(&writer, indent, &writer_vtable, &state);
361
362 json_dump_recursive(&writer, json, 0);
363
364 json_writer_output_char(&state, 0);
365
366 return state.output;
367 }
368