LXR qemu/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 "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
  22static 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
  31void 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
  94out_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
 102void 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
 118void json_message_parser_feed(JSONMessageParser *parser,
 119                             const char *buffer, size_t size)
 120{
 121    json_lexer_feed(&parser->lexer, buffer, size);
 122}
 123
 124void json_message_parser_flush(JSONMessageParser *parser)
 125{
 126    json_lexer_flush(&parser->lexer);
 127    assert(g_queue_is_empty(&parser->tokens));
 128}
 129
 130void json_message_parser_destroy(JSONMessageParser *parser)
 131{
 132    json_lexer_destroy(&parser->lexer);
 133    json_message_free_tokens(parser);
 134}
 135