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1 | /* | |
2 | * JSON streaming support | |
3 | * | |
4 | * Copyright IBM, Corp. 2009 | |
5 | * | |
6 | * Authors: | |
7 | * Anthony Liguori <aliguori@us.ibm.com> | |
8 | * | |
9 | * This work is licensed under the terms of the GNU LGPL, version 2.1 or later. | |
10 | * See the COPYING.LIB file in the top-level directory. | |
11 | * | |
12 | */ | |
13 | ||
14 | #include "qemu/osdep.h" | |
15 | #include "qapi/error.h" | |
16 | #include "json-parser-int.h" | |
17 | ||
18 | #define MAX_TOKEN_SIZE (64ULL << 20) | |
19 | #define MAX_TOKEN_COUNT (2ULL << 20) | |
20 | #define MAX_NESTING (1 << 10) | |
21 | ||
22 | static void json_message_free_tokens(JSONMessageParser *parser) | |
23 | { | |
24 | JSONToken *token; | |
25 | ||
26 | while ((token = g_queue_pop_head(&parser->tokens))) { | |
27 | g_free(token); | |
28 | } | |
29 | } | |
30 | ||
31 | void json_message_process_token(JSONLexer *lexer, GString *input, | |
32 | JSONTokenType type, int x, int y) | |
33 | { | |
34 | JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer); | |
35 | QObject *json = NULL; | |
36 | Error *err = NULL; | |
37 | JSONToken *token; | |
38 | ||
39 | switch (type) { | |
40 | case JSON_LCURLY: | |
41 | parser->brace_count++; | |
42 | break; | |
43 | case JSON_RCURLY: | |
44 | parser->brace_count--; | |
45 | break; | |
46 | case JSON_LSQUARE: | |
47 | parser->bracket_count++; | |
48 | break; | |
49 | case JSON_RSQUARE: | |
50 | parser->bracket_count--; | |
51 | break; | |
52 | case JSON_ERROR: | |
53 | error_setg(&err, "JSON parse error, stray '%s'", input->str); | |
54 | goto out_emit; | |
55 | case JSON_END_OF_INPUT: | |
56 | if (g_queue_is_empty(&parser->tokens)) { | |
57 | return; | |
58 | } | |
59 | json = json_parser_parse(&parser->tokens, parser->ap, &err); | |
60 | goto out_emit; | |
61 | default: | |
62 | break; | |
63 | } | |
64 | ||
65 | /* | |
66 | * Security consideration, we limit total memory allocated per object | |
67 | * and the maximum recursion depth that a message can force. | |
68 | */ | |
69 | if (parser->token_size + input->len + 1 > MAX_TOKEN_SIZE) { | |
70 | error_setg(&err, "JSON token size limit exceeded"); | |
71 | goto out_emit; | |
72 | } | |
73 | if (g_queue_get_length(&parser->tokens) + 1 > MAX_TOKEN_COUNT) { | |
74 | error_setg(&err, "JSON token count limit exceeded"); | |
75 | goto out_emit; | |
76 | } | |
77 | if (parser->bracket_count + parser->brace_count > MAX_NESTING) { | |
78 | error_setg(&err, "JSON nesting depth limit exceeded"); | |
79 | goto out_emit; | |
80 | } | |
81 | ||
82 | token = json_token(type, x, y, input); | |
83 | parser->token_size += input->len; | |
84 | ||
85 | g_queue_push_tail(&parser->tokens, token); | |
86 | ||
87 | if ((parser->brace_count > 0 || parser->bracket_count > 0) | |
88 | && parser->bracket_count >= 0 && parser->bracket_count >= 0) { | |
89 | return; | |
90 | } | |
91 | ||
92 | json = json_parser_parse(&parser->tokens, parser->ap, &err); | |
93 | ||
94 | out_emit: | |
95 | parser->brace_count = 0; | |
96 | parser->bracket_count = 0; | |
97 | json_message_free_tokens(parser); | |
98 | parser->token_size = 0; | |
99 | parser->emit(parser->opaque, json, err); | |
100 | } | |
101 | ||
102 | void json_message_parser_init(JSONMessageParser *parser, | |
103 | void (*emit)(void *opaque, QObject *json, | |
104 | Error *err), | |
105 | void *opaque, va_list *ap) | |
106 | { | |
107 | parser->emit = emit; | |
108 | parser->opaque = opaque; | |
109 | parser->ap = ap; | |
110 | parser->brace_count = 0; | |
111 | parser->bracket_count = 0; | |
112 | g_queue_init(&parser->tokens); | |
113 | parser->token_size = 0; | |
114 | ||
115 | json_lexer_init(&parser->lexer, !!ap); | |
116 | } | |
117 | ||
118 | void json_message_parser_feed(JSONMessageParser *parser, | |
119 | const char *buffer, size_t size) | |
120 | { | |
121 | json_lexer_feed(&parser->lexer, buffer, size); | |
122 | } | |
123 | ||
124 | void json_message_parser_flush(JSONMessageParser *parser) | |
125 | { | |
126 | json_lexer_flush(&parser->lexer); | |
127 | assert(g_queue_is_empty(&parser->tokens)); | |
128 | } | |
129 | ||
130 | void json_message_parser_destroy(JSONMessageParser *parser) | |
131 | { | |
132 | json_lexer_destroy(&parser->lexer); | |
133 | json_message_free_tokens(parser); | |
134 | } |