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 "qlist.h"
  15 #include "qint.h"
  16 #include "qdict.h"
  17 #include "qemu-common.h"
  18 #include "json-lexer.h"
  19 #include "json-streamer.h"
  20
  21 #define MAX_TOKEN_SIZE (64ULL << 20)
  22 #define MAX_NESTING (1ULL << 10)
  23
  24 static 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 (parser->brace_count < 0 ||
  60         parser->bracket_count < 0 ||
  61         (parser->brace_count == 0 &&
  62          parser->bracket_count == 0)) {
  63         parser->brace_count = 0;
  64         parser->bracket_count = 0;
  65         parser->emit(parser, parser->tokens);
  66         QDECREF(parser->tokens);
  67         parser->tokens = qlist_new();
  68     } else if (parser->token_size > MAX_TOKEN_SIZE ||
  69                parser->bracket_count > MAX_NESTING ||
  70                parser->brace_count > MAX_NESTING) {
  71         /* Security consideration, we limit total memory allocated per object
  72          * and the maximum recursion depth that a message can force.
  73          */
  74         parser->brace_count = 0;
  75         parser->bracket_count = 0;
  76         parser->emit(parser, parser->tokens);
  77         QDECREF(parser->tokens);
  78         parser->tokens = qlist_new();
  79     }
  80 }
  81
  82 void json_message_parser_init(JSONMessageParser *parser,
  83                               void (*func)(JSONMessageParser *, QList *))
  84 {
  85     parser->emit = func;
  86     parser->brace_count = 0;
  87     parser->bracket_count = 0;
  88     parser->tokens = qlist_new();
  89     parser->token_size = 0;
  90
  91     json_lexer_init(&parser->lexer, json_message_process_token);
  92 }
  93
  94 int json_message_parser_feed(JSONMessageParser *parser,
  95                              const char *buffer, size_t size)
  96 {
  97     return json_lexer_feed(&parser->lexer, buffer, size);
  98 }
  99
 100 int json_message_parser_flush(JSONMessageParser *parser)
 101 {
 102     return json_lexer_flush(&parser->lexer);
 103 }
 104
 105 void json_message_parser_destroy(JSONMessageParser *parser)
 106 {
 107     json_lexer_destroy(&parser->lexer);
 108     QDECREF(parser->tokens);
 109 }