migration: split migration hooks out of QEMUFileOps
[qemu.git] / qobject / json-streamer.c
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 "qemu-common.h"
16 #include "qapi/qmp/json-lexer.h"
17 #include "qapi/qmp/json-streamer.h"
18
19 #define MAX_TOKEN_SIZE (64ULL << 20)
20 #define MAX_TOKEN_COUNT (2ULL << 20)
21 #define MAX_NESTING (1ULL << 10)
22
23 static void json_message_free_tokens(JSONMessageParser *parser)
24 {
25 if (parser->tokens) {
26 g_queue_free(parser->tokens);
27 parser->tokens = NULL;
28 }
29 }
30
31 static 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 JSONToken *token;
36
37 switch (type) {
38 case JSON_LCURLY:
39 parser->brace_count++;
40 break;
41 case JSON_RCURLY:
42 parser->brace_count--;
43 break;
44 case JSON_LSQUARE:
45 parser->bracket_count++;
46 break;
47 case JSON_RSQUARE:
48 parser->bracket_count--;
49 break;
50 default:
51 break;
52 }
53
54 token = g_malloc(sizeof(JSONToken) + input->len + 1);
55 token->type = type;
56 memcpy(token->str, input->str, input->len);
57 token->str[input->len] = 0;
58 token->x = x;
59 token->y = y;
60
61 parser->token_size += input->len;
62
63 g_queue_push_tail(parser->tokens, token);
64
65 if (type == JSON_ERROR) {
66 goto out_emit_bad;
67 } else if (parser->brace_count < 0 ||
68 parser->bracket_count < 0 ||
69 (parser->brace_count == 0 &&
70 parser->bracket_count == 0)) {
71 goto out_emit;
72 } else if (parser->token_size > MAX_TOKEN_SIZE ||
73 g_queue_get_length(parser->tokens) > MAX_TOKEN_COUNT ||
74 parser->bracket_count + parser->brace_count > MAX_NESTING) {
75 /* Security consideration, we limit total memory allocated per object
76 * and the maximum recursion depth that a message can force.
77 */
78 goto out_emit_bad;
79 }
80
81 return;
82
83 out_emit_bad:
84 /*
85 * Clear out token list and tell the parser to emit an error
86 * indication by passing it a NULL list
87 */
88 json_message_free_tokens(parser);
89 out_emit:
90 /* send current list of tokens to parser and reset tokenizer */
91 parser->brace_count = 0;
92 parser->bracket_count = 0;
93 /* parser->emit takes ownership of parser->tokens. */
94 parser->emit(parser, parser->tokens);
95 parser->tokens = g_queue_new();
96 parser->token_size = 0;
97 }
98
99 void json_message_parser_init(JSONMessageParser *parser,
100 void (*func)(JSONMessageParser *, GQueue *))
101 {
102 parser->emit = func;
103 parser->brace_count = 0;
104 parser->bracket_count = 0;
105 parser->tokens = g_queue_new();
106 parser->token_size = 0;
107
108 json_lexer_init(&parser->lexer, json_message_process_token);
109 }
110
111 int json_message_parser_feed(JSONMessageParser *parser,
112 const char *buffer, size_t size)
113 {
114 return json_lexer_feed(&parser->lexer, buffer, size);
115 }
116
117 int json_message_parser_flush(JSONMessageParser *parser)
118 {
119 return json_lexer_flush(&parser->lexer);
120 }
121
122 void json_message_parser_destroy(JSONMessageParser *parser)
123 {
124 json_lexer_destroy(&parser->lexer);
125 json_message_free_tokens(parser);
126 }