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wireshark/wsutil/json_dumper.c

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/* wsjson.h
* 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>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "json_dumper.h"
#define WS_LOG_DOMAIN LOG_DOMAIN_WSUTIL
#include <math.h>
#include <wsutil/wslog.h>
/*
* json_dumper.state[current_depth] describes a nested element:
* - type: none/object/array/value
* - has_name: Whether the object member name was set.
*/
enum json_dumper_element_type {
JSON_DUMPER_TYPE_NONE = 0,
JSON_DUMPER_TYPE_VALUE = 1,
JSON_DUMPER_TYPE_OBJECT = 2,
JSON_DUMPER_TYPE_ARRAY = 3,
JSON_DUMPER_TYPE_BASE64 = 4,
};
#define JSON_DUMPER_TYPE(state) ((enum json_dumper_element_type)((state) & 7))
#define JSON_DUMPER_HAS_NAME (1 << 3)
#define JSON_DUMPER_FLAGS_ERROR (1 << 16) /* Output flag: an error occurred. */
enum json_dumper_change {
JSON_DUMPER_BEGIN,
JSON_DUMPER_END,
JSON_DUMPER_SET_NAME,
JSON_DUMPER_SET_VALUE,
JSON_DUMPER_WRITE_BASE64,
JSON_DUMPER_FINISH,
};
/* JSON Dumper putc */
static void
jd_putc(const json_dumper *dumper, char c)
{
if (dumper->output_file) {
fputc(c, dumper->output_file);
}
if (dumper->output_string) {
g_string_append_c(dumper->output_string, c);
}
}
/* JSON Dumper puts */
static void
jd_puts(const json_dumper *dumper, const char *s)
{
if (dumper->output_file) {
fputs(s, dumper->output_file);
}
if (dumper->output_string) {
g_string_append(dumper->output_string, s);
}
}
static void
jd_puts_len(const json_dumper *dumper, const char *s, gsize len)
{
if (dumper->output_file) {
fwrite(s, 1, len, dumper->output_file);
}
if (dumper->output_string) {
g_string_append_len(dumper->output_string, s, len);
}
}
static void
jd_vprintf(const json_dumper *dumper, const char *format, va_list args)
{
if (dumper->output_file) {
vfprintf(dumper->output_file, format, args);
}
if (dumper->output_string) {
g_string_append_vprintf(dumper->output_string, format, args);
}
}
static void
json_puts_string(const json_dumper *dumper, const char *str, gboolean dot_to_underscore)
{
if (!str) {
jd_puts(dumper, "null");
return;
}
static const char json_cntrl[0x20][6] = {
"u0000", "u0001", "u0002", "u0003", "u0004", "u0005", "u0006", "u0007", "b", "t", "n", "u000b", "f", "r", "u000e", "u000f",
"u0010", "u0011", "u0012", "u0013", "u0014", "u0015", "u0016", "u0017", "u0018", "u0019", "u001a", "u001b", "u001c", "u001d", "u001e", "u001f"
};
jd_putc(dumper, '"');
for (int i = 0; str[i]; i++) {
if ((guint)str[i] < 0x20) {
jd_putc(dumper, '\\');
jd_puts(dumper, json_cntrl[(guint)str[i]]);
} else if (i > 0 && str[i - 1] == '<' && str[i] == '/') {
// Convert </script> to <\/script> to avoid breaking web pages.
jd_puts(dumper, "\\/");
} else {
if (str[i] == '\\' || str[i] == '"') {
jd_putc(dumper, '\\');
}
if (dot_to_underscore && str[i] == '.')
jd_putc(dumper, '_');
else
jd_putc(dumper, str[i]);
}
}
jd_putc(dumper, '"');
}
/**
* 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;
}
if (dumper->output_file) {
fflush(dumper->output_file);
}
ws_error("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.
*/
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;
}
int depth = dumper->current_depth;
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;
}
guint8 prev_state = depth > 0 ? dumper->state[depth - 1] : 0;
enum json_dumper_element_type prev_type = JSON_DUMPER_TYPE(prev_state);
gboolean ok = FALSE;
switch (change) {
case JSON_DUMPER_BEGIN:
ok = depth + 1 < JSON_DUMPER_MAX_DEPTH;
break;
case JSON_DUMPER_END:
ok = prev_type == type && !(prev_state & JSON_DUMPER_HAS_NAME);
break;
case JSON_DUMPER_SET_NAME:
/* An object name can only be set once before a value is set. */
ok = prev_type == JSON_DUMPER_TYPE_OBJECT && !(prev_state & JSON_DUMPER_HAS_NAME);
break;
case JSON_DUMPER_SET_VALUE:
if (prev_type == JSON_DUMPER_TYPE_OBJECT) {
ok = (prev_state & JSON_DUMPER_HAS_NAME);
} else if (prev_type == JSON_DUMPER_TYPE_ARRAY) {
ok = TRUE;
} else if (prev_type == JSON_DUMPER_TYPE_BASE64) {
ok = FALSE;
} else {
ok = JSON_DUMPER_TYPE(dumper->state[depth]) == JSON_DUMPER_TYPE_NONE;
}
break;
case JSON_DUMPER_WRITE_BASE64:
ok = (prev_type == JSON_DUMPER_TYPE_BASE64) &&
(type == JSON_DUMPER_TYPE_NONE || type == JSON_DUMPER_TYPE_BASE64);
break;
case JSON_DUMPER_FINISH:
ok = depth == 0;
break;
}
if (!ok) {
dumper->flags |= JSON_DUMPER_FLAGS_ERROR;
json_dumper_bad(dumper, change, type, "illegal transition");
}
return ok;
}
static void
print_newline_indent(const json_dumper *dumper, int depth)
{
if ((dumper->flags & JSON_DUMPER_FLAGS_PRETTY_PRINT)) {
jd_putc(dumper, '\n');
for (int i = 0; i < depth; i++) {
jd_puts(dumper, " ");
}
}
}
/**
* Prints commas, newlines and indentation (if necessary). Used for array
* values, object names and normal values (strings, etc.).
*/
static void
prepare_token(json_dumper *dumper)
{
if (dumper->current_depth == 0) {
// not part of an array or object.
return;
}
guint8 prev_state = dumper->state[dumper->current_depth - 1];
// While processing the object value, reset the key state as it is consumed.
dumper->state[dumper->current_depth - 1] &= ~JSON_DUMPER_HAS_NAME;
switch (JSON_DUMPER_TYPE(prev_state)) {
case JSON_DUMPER_TYPE_OBJECT:
if ((prev_state & JSON_DUMPER_HAS_NAME)) {
// Object key already set, value follows. No indentation needed.
return;
}
break;
case JSON_DUMPER_TYPE_ARRAY:
break;
default:
// Initial values do not need indentation.
return;
}
if (dumper->state[dumper->current_depth]) {
jd_putc(dumper, ',');
}
print_newline_indent(dumper, dumper->current_depth);
}
/**
* Common code to close an object/array, printing a closing character (and if
* necessary, it is preceded by newline and indentation).
*/
static void
finish_token(const json_dumper *dumper, char close_char)
{
// if the object/array was non-empty, add a newline and indentation.
if (dumper->state[dumper->current_depth]) {
print_newline_indent(dumper, dumper->current_depth - 1);
}
jd_putc(dumper, close_char);
}
void
json_dumper_begin_object(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_BEGIN, JSON_DUMPER_TYPE_OBJECT)) {
return;
}
prepare_token(dumper);
jd_putc(dumper, '{');
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_OBJECT;
++dumper->current_depth;
dumper->state[dumper->current_depth] = 0;
}
void
json_dumper_set_member_name(json_dumper *dumper, const char *name)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_NAME, JSON_DUMPER_TYPE_NONE)) {
return;
}
prepare_token(dumper);
json_puts_string(dumper, name, dumper->flags & JSON_DUMPER_DOT_TO_UNDERSCORE);
jd_putc(dumper, ':');
if ((dumper->flags & JSON_DUMPER_FLAGS_PRETTY_PRINT)) {
jd_putc(dumper, ' ');
}
dumper->state[dumper->current_depth - 1] |= JSON_DUMPER_HAS_NAME;
}
void
json_dumper_end_object(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_END, JSON_DUMPER_TYPE_OBJECT)) {
return;
}
finish_token(dumper, '}');
--dumper->current_depth;
}
void
json_dumper_begin_array(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_BEGIN, JSON_DUMPER_TYPE_ARRAY)) {
return;
}
prepare_token(dumper);
jd_putc(dumper, '[');
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_ARRAY;
++dumper->current_depth;
dumper->state[dumper->current_depth] = 0;
}
void
json_dumper_end_array(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_END, JSON_DUMPER_TYPE_ARRAY)) {
return;
}
finish_token(dumper, ']');
--dumper->current_depth;
}
void
json_dumper_value_string(json_dumper *dumper, const char *value)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_VALUE, JSON_DUMPER_TYPE_VALUE)) {
return;
}
prepare_token(dumper);
json_puts_string(dumper, value, FALSE);
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_VALUE;
}
void
json_dumper_value_double(json_dumper *dumper, double value)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_VALUE, JSON_DUMPER_TYPE_VALUE)) {
return;
}
prepare_token(dumper);
gchar buffer[G_ASCII_DTOSTR_BUF_SIZE] = { 0 };
if (isfinite(value) && g_ascii_dtostr(buffer, G_ASCII_DTOSTR_BUF_SIZE, value) && buffer[0]) {
jd_puts(dumper, buffer);
} else {
jd_puts(dumper, "null");
}
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_VALUE;
}
void
json_dumper_value_va_list(json_dumper *dumper, const char *format, va_list ap)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_SET_VALUE, JSON_DUMPER_TYPE_VALUE)) {
return;
}
prepare_token(dumper);
jd_vprintf(dumper, format, ap);
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_VALUE;
}
void
json_dumper_value_anyf(json_dumper *dumper, const char *format, ...)
{
va_list ap;
va_start(ap, format);
json_dumper_value_va_list(dumper, format, ap);
va_end(ap);
}
gboolean
json_dumper_finish(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_FINISH, JSON_DUMPER_TYPE_NONE)) {
return FALSE;
}
jd_putc(dumper, '\n');
dumper->state[0] = 0;
return TRUE;
}
void
json_dumper_begin_base64(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_BEGIN, JSON_DUMPER_TYPE_BASE64)) {
return;
}
dumper->base64_state = 0;
dumper->base64_save = 0;
prepare_token(dumper);
jd_putc(dumper, '"');
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_BASE64;
++dumper->current_depth;
dumper->state[dumper->current_depth] = 0;
}
void
json_dumper_write_base64(json_dumper* dumper, const guchar *data, size_t len)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_WRITE_BASE64, JSON_DUMPER_TYPE_BASE64)) {
return;
}
#define CHUNK_SIZE 1024
gchar buf[(CHUNK_SIZE / 3 + 1) * 4 + 4];
while (len > 0) {
gsize chunk_size = len < CHUNK_SIZE ? len : CHUNK_SIZE;
gsize output_size = g_base64_encode_step(data, chunk_size, FALSE, buf, &dumper->base64_state, &dumper->base64_save);
jd_puts_len(dumper, buf, output_size);
data += chunk_size;
len -= chunk_size;
}
dumper->state[dumper->current_depth] = JSON_DUMPER_TYPE_BASE64;
}
void
json_dumper_end_base64(json_dumper *dumper)
{
if (!json_dumper_check_state(dumper, JSON_DUMPER_END, JSON_DUMPER_TYPE_BASE64)) {
return;
}
gchar buf[4];
gsize wrote;
wrote = g_base64_encode_close(FALSE, buf, &dumper->base64_state, &dumper->base64_save);
jd_puts_len(dumper, buf, wrote);
jd_putc(dumper, '"');
--dumper->current_depth;
}
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