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 "qapi/qmp/qlist.h"
15#include "qapi/qmp/qint.h"
16#include "qapi/qmp/qdict.h"
17#include "qemu-common.h"
18#include "qapi/qmp/json-lexer.h"
19#include "qapi/qmp/json-streamer.h"
20
21#define MAX_TOKEN_SIZE (64ULL << 20)
22#define MAX_NESTING (1ULL << 10)
23
24static void json_message_process_token(JSONLexer *lexer, QString *token, JSONTokenType type, int x, int y)
25{
26    JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer);
27    QDict *dict;
28
29    if (type == JSON_OPERATOR) {
30        switch (qstring_get_str(token)[0]) {
31        case '{':
32            parser->brace_count++;
33            break;
34        case '}':
35            parser->brace_count--;
36            break;
37        case '[':
38            parser->bracket_count++;
39            break;
40        case ']':
41            parser->bracket_count--;
42            break;
43        default:
44            break;
45        }
46    }
47
48    dict = qdict_new();
49    qdict_put(dict, "type", qint_from_int(type));
50    QINCREF(token);
51    qdict_put(dict, "token", token);
52    qdict_put(dict, "x", qint_from_int(x));
53    qdict_put(dict, "y", qint_from_int(y));
54
55    parser->token_size += token->length;
56
57    qlist_append(parser->tokens, dict);
58
59    if (type == JSON_ERROR) {
60        goto out_emit_bad;
61    } else if (parser->brace_count < 0 ||
62        parser->bracket_count < 0 ||
63        (parser->brace_count == 0 &&
64         parser->bracket_count == 0)) {
65        goto out_emit;
66    } else if (parser->token_size > MAX_TOKEN_SIZE ||
67               parser->bracket_count > MAX_NESTING ||
68               parser->brace_count > MAX_NESTING) {
69        /* Security consideration, we limit total memory allocated per object
70         * and the maximum recursion depth that a message can force.
71         */
72        goto out_emit;
73    }
74
75    return;
76
77out_emit_bad:
78    /* clear out token list and tell the parser to emit and error
79     * indication by passing it a NULL list
80     */
81    QDECREF(parser->tokens);
82    parser->tokens = NULL;
83out_emit:
84    /* send current list of tokens to parser and reset tokenizer */
85    parser->brace_count = 0;
86    parser->bracket_count = 0;
87    parser->emit(parser, parser->tokens);
88    if (parser->tokens) {
89        QDECREF(parser->tokens);
90    }
91    parser->tokens = qlist_new();
92    parser->token_size = 0;
93}
94
95void json_message_parser_init(JSONMessageParser *parser,
96                              void (*func)(JSONMessageParser *, QList *))
97{
98    parser->emit = func;
99    parser->brace_count = 0;
100    parser->bracket_count = 0;
101    parser->tokens = qlist_new();
102    parser->token_size = 0;
103
104    json_lexer_init(&parser->lexer, json_message_process_token);
105}
106
107int json_message_parser_feed(JSONMessageParser *parser,
108                             const char *buffer, size_t size)
109{
110    return json_lexer_feed(&parser->lexer, buffer, size);
111}
112
113int json_message_parser_flush(JSONMessageParser *parser)
114{
115    return json_lexer_flush(&parser->lexer);
116}
117
118void json_message_parser_destroy(JSONMessageParser *parser)
119{
120    json_lexer_destroy(&parser->lexer);
121    QDECREF(parser->tokens);
122}
123