a6ccd15275
jsmn_validate puts a maximum number of tokens allowed. Add a function to call jsmn_parse without calling strlen (so it both works without a null terminated string and is more efficient when we already know the length) and call that instead. Add a comment that we might want to change jsmn_validate to just set a maximum length, instead of allocating memory for an array of tokens that are filled out and then freed. Even if jsmn_validate is changed, the new function would still be useful for parsing partial JSON, whether truncated files or if the heuristics decided to make a decision after less than an entire file. Fix #17589
116 lines
3.1 KiB
C
116 lines
3.1 KiB
C
/* json.c
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*
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* Copyright 2015, Dario Lombardo <lomato@gmail.com>
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include "json.h"
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#include <string.h>
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#include "wtap-int.h"
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#include "file_wrappers.h"
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#include <wsutil/wsjson.h>
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/* Maximum size of json file. */
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#define MAX_FILE_SIZE (50*1024*1024)
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static int json_file_type_subtype = -1;
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void register_json(void);
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wtap_open_return_val json_open(wtap *wth, int *err, char **err_info)
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{
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uint8_t* filebuf;
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int bytes_read;
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/* XXX checking the full file contents might be a bit expensive, maybe
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* resort to simpler heuristics like '{' or '[' (with some other chars)? */
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filebuf = (uint8_t*)g_malloc0(MAX_FILE_SIZE);
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if (!filebuf)
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return WTAP_OPEN_ERROR;
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bytes_read = file_read(filebuf, MAX_FILE_SIZE, wth->fh);
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if (bytes_read < 0) {
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/* Read error. */
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*err = file_error(wth->fh, err_info);
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g_free(filebuf);
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return WTAP_OPEN_ERROR;
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}
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if (bytes_read == 0) {
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/* empty file, not *anybody's* */
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g_free(filebuf);
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return WTAP_OPEN_NOT_MINE;
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}
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/* We could reduce the maximum size to read and accept if the parser
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* returns JSMN_ERROR_PART (i.e., only fail on JSMN_ERROR_INVAL as we
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* shouldn't get JSMN_ERROR_NOMEM if tokens is NULL.) That way we
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* could handle bigger files without testing the entire file.
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* packet-json shows excess unparsed data at the end with the
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* data-text-lines dissector.
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*/
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if (json_parse_len(filebuf, bytes_read, NULL, 0) < 0) {
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g_free(filebuf);
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return WTAP_OPEN_NOT_MINE;
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}
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if (file_seek(wth->fh, 0, SEEK_SET, err) == -1) {
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g_free(filebuf);
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return WTAP_OPEN_ERROR;
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}
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wth->file_type_subtype = json_file_type_subtype;
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wth->file_encap = WTAP_ENCAP_JSON;
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wth->file_tsprec = WTAP_TSPREC_SEC;
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wth->subtype_read = wtap_full_file_read;
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wth->subtype_seek_read = wtap_full_file_seek_read;
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wth->snapshot_length = 0;
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g_free(filebuf);
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return WTAP_OPEN_MINE;
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}
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static const struct supported_block_type json_blocks_supported[] = {
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/*
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* This is a file format that we dissect, so we provide only one
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* "packet" with the file's contents, and don't support any
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* options.
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*/
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{ WTAP_BLOCK_PACKET, ONE_BLOCK_SUPPORTED, NO_OPTIONS_SUPPORTED }
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};
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static const struct file_type_subtype_info json_info = {
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"JavaScript Object Notation", "json", "json", NULL,
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false, BLOCKS_SUPPORTED(json_blocks_supported),
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NULL, NULL, NULL
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};
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void register_json(void)
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{
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json_file_type_subtype = wtap_register_file_type_subtype(&json_info);
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/*
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* Register name for backwards compatibility with the
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* wtap_filetypes table in Lua.
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*/
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wtap_register_backwards_compatibility_lua_name("JSON",
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json_file_type_subtype);
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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