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json_dumper: add debugging print as corruption check 

Print warnings to help with debugging. Add Jakub (author of
json_puts_string).

Change-Id: I8bf039afc21357e97accb2a9abf9378735af12eb
Reviewed-on: https://code.wireshark.org/review/31041
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Dario Lombardo <lomato@gmail.com>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
This commit is contained in:
Peter Wu 2018-12-14 00:21:51 +01:00
parent a1ef5f6899
commit cd41203949
2 changed files with 34 additions and 1 deletions
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2
wsutil/CMakeLists.txt
View File

@ -291,7 +291,7 @@ CHECKAPI(
NAME
wsutil
SWITCHES
--group termoutput:1 --summary-group termoutput --build
--group termoutput:2 --summary-group termoutput --build
SOURCES
${WSUTIL_COMMON_FILES}
)

33
wsutil/json_dumper.c
View File

@ -2,6 +2,7 @@
* Routines for serializing data as JSON.
*
* Copyright 2018, Peter Wu <peter@lekensteyn.nl>
* Copyright (C) 2016 Jakub Zawadzki
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
@ -27,6 +28,7 @@ enum json_dumper_element_type {
#define JSON_DUMPER_HAS_NAME (1 << 2)
#define JSON_DUMPER_FLAGS_ERROR (1 << 16) /* Output flag: an error occurred. */
#define JSON_DUMPER_FLAGS_NO_DEBUG (1 << 17) /* Input flag: disable debug prints (intended for speeding up fuzzing). */
enum json_dumper_change {
JSON_DUMPER_BEGIN,
@ -67,6 +69,34 @@ json_puts_string(FILE *fp, const char *str, gboolean dot_to_underscore)
fputc('"', fp);
}
/**
* Called when a programming error is encountered where the JSON manipulation
* state got corrupted. This could happen when pairing the wrong begin/end
* calls, when writing multiple values for the same object, etc.
*/
static void
json_dumper_bad(json_dumper *dumper, enum json_dumper_change change,
enum json_dumper_element_type type, const char *what)
{
unsigned states[3];
int depth = dumper->current_depth;
/* Do not use add/subtract from depth to avoid signed overflow. */
int adj = -1;
for (int i = 0; i < 3; i++, adj++) {
if (depth >= -adj && depth < JSON_DUMPER_MAX_DEPTH - adj) {
states[i] = dumper->state[depth + adj];
} else {
states[i] = 0xbad;
}
}
if ((dumper->flags & JSON_DUMPER_FLAGS_NO_DEBUG)) {
/* Console output can be slow, disable log calls to speed up fuzzing. */
return;
}
g_warning("Bad json_dumper state: %s; change=%d type=%d depth=%d prev/curr/next state=%02x %02x %02x",
what, change, type, dumper->current_depth, states[0], states[1], states[2]);
}
/**
* Checks that the dumper state is valid for a new change. Any error will be
* sticky and prevent further dumps from succeeding.
@ -75,6 +105,7 @@ static gboolean
json_dumper_check_state(json_dumper *dumper, enum json_dumper_change change, enum json_dumper_element_type type)
{
if ((dumper->flags & JSON_DUMPER_FLAGS_ERROR)) {
json_dumper_bad(dumper, change, type, "previous corruption detected");
return FALSE;
}
@ -82,6 +113,7 @@ json_dumper_check_state(json_dumper *dumper, enum json_dumper_change change, enu
if (depth < 0 || depth >= JSON_DUMPER_MAX_DEPTH) {
/* Corrupted state, no point in continuing. */
dumper->flags |= JSON_DUMPER_FLAGS_ERROR;
json_dumper_bad(dumper, change, type, "depth corruption");
return FALSE;
}
@ -115,6 +147,7 @@ json_dumper_check_state(json_dumper *dumper, enum json_dumper_change change, enu
}
if (!ok) {
dumper->flags |= JSON_DUMPER_FLAGS_ERROR;
json_dumper_bad(dumper, change, type, "illegal transition");
}
return ok;
}