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/****************************************************************************
**
** Copyright (C) 2021 Intel Corporation
**
** Permission is hereby granted, free of charge, to any person obtaining a copy
** of this software and associated documentation files (the "Software"), to deal
** in the Software without restriction, including without limitation the rights
** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
** copies of the Software, and to permit persons to whom the Software is
** furnished to do so, subject to the following conditions:
**
** The above copyright notice and this permission notice shall be included in
** all copies or substantial portions of the Software.
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
** THE SOFTWARE.
**
****************************************************************************/
#define _BSD_SOURCE 1
#define _DEFAULT_SOURCE 1
#define _GNU_SOURCE 1
#ifndef __STDC_LIMIT_MACROS
# define __STDC_LIMIT_MACROS 1
#endif
#include "cbor.h"
#include "cborjson.h"
#include "cborinternal_p.h"
#include "compilersupport_p.h"
#include "cborinternal_p.h"
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/**
* \defgroup CborToJson Converting CBOR to JSON
* \brief Group of functions used to convert CBOR to JSON.
*
* This group contains two functions that can be used to convert a \ref
* CborValue object to an equivalent JSON representation. This module attempts
* to follow the recommendations from RFC 7049 section 4.1 "Converting from
* CBOR to JSON", though it has a few differences. They are noted below.
*
* These functions produce a "minified" JSON output, with no spacing,
* indentation or line breaks. If those are necessary, they need to be applied
* in a post-processing phase.
*
* Note that JSON cannot support all CBOR types with fidelity, so the
* conversion is usually lossy. For that reason, TinyCBOR supports adding a set
* of metadata JSON values that can be used by a JSON-to-CBOR converter to
* restore the original data types.
*
* The TinyCBOR library does not provide a way to convert from JSON
* representation back to encoded form. However, it provides a tool called
* \c json2cbor which can be used for that purpose. That tool supports the
* metadata format that these functions may produce.
*
* Either of the functions in this section will attempt to convert exactly one
* CborValue object to JSON. Those functions may return any error documented
* for the functions for CborParsing. In addition, if the C standard library
* stream functions return with error, the text conversion will return with
* error CborErrorIO.
*
* These functions also perform UTF-8 validation in CBOR text strings. If they
* encounter a sequence of bytes that is not permitted in UTF-8, they will return
* CborErrorInvalidUtf8TextString. That includes encoding of surrogate points
* in UTF-8.
*
* \warning The metadata produced by these functions is not guaranteed to
* remain stable. A future update of TinyCBOR may produce different output for
* the same input and parsers may be unable to handle it.
*
* \sa CborParsing, CborPretty, cbor_parser_init()
*/
/**
* \addtogroup CborToJson
* @{
* <h2 class="groupheader">Conversion limitations</h2>
*
* When converting from CBOR to JSON, there may be information loss. This
* section lists the possible scenarios.
*
* \par Number precision:
* ALL JSON numbers, due to its JavaScript heritage, are IEEE 754
* double-precision floating point. This means JSON is not capable of
* representing all integers numbers outside the range [-(2<sup>53</sup>)+1,
* 2<sup>53</sup>-1] and is not capable of representing NaN or infinite. If the
* CBOR data contains a number outside the valid range, the conversion will
* lose precision. If the input was NaN or infinite, the result of the
* conversion will be the JSON null value. In addition, the distinction between
* half-, single- and double-precision is lost.
*
* \par
* If enabled, the original value and original type are stored in the metadata.
*
* \par Non-native types:
* CBOR's type system is richer than JSON's, which means some data values
* cannot be represented when converted to JSON. The conversion silently turns
* them into strings: CBOR simple types become "simple(nn)" where \c nn is the
* simple type's value, with the exception of CBOR undefined, which becomes
* "undefined", while CBOR byte strings are converted to an Base16, Base64, or
* Base64url encoding
*
* \par
* If enabled, the original type is stored in the metadata.
*
* \par Presence of tags:
* JSON has no support for tagged values, so by default tags are dropped when
* converting to JSON. However, if the CborConvertObeyByteStringTags option is
* active (default), then certain known tags are honored and are used to format
* the conversion of the tagged byte string to JSON.
*
* \par
* If the CborConvertTagsToObjects option is active, then the tag and the
* tagged value are converted to a JSON object. Otherwise, if enabled, the
* last (innermost) tag is stored in the metadata.
*
* \par Non-string keys in maps:
* JSON requires all Object keys to be strings, while CBOR does not. By
* default, if a non-string key is found, the conversion fails with error
* CborErrorJsonObjectKeyNotString. If the CborConvertStringifyMapKeys option
* is active, then the conversion attempts to create a string representation
* using CborPretty. Note that the \c json2cbor tool is not able to parse this
* back to the original form.
*
* \par Duplicate keys in maps:
* Neither JSON nor CBOR allow duplicated keys, but current TinyCBOR does not
* validate that this is the case. If there are duplicated keys in the input,
* they will be repeated in the output, which many JSON tools may flag as
* invalid. In addition to that, if the CborConvertStringifyMapKeys option is
* active, it is possible that a non-string key in a CBOR map will be converted
* to a string form that is identical to another key.
*
* \par
* When metadata support is active, the conversion will add extra key-value
* pairs to the JSON output so it can store the metadata. It is possible that
* the keys for the metadata clash with existing keys in the JSON map.
*/
extern FILE *open_memstream(char **bufptr, size_t *sizeptr);
enum ConversionStatusFlags {
TypeWasNotNative = 0x100, /* anything but strings, boolean, null, arrays and maps */
TypeWasTagged = 0x200,
NumberPrecisionWasLost = 0x400,
NumberWasNaN = 0x800,
NumberWasInfinite = 0x1000,
NumberWasNegative = 0x2000, /* only used with NumberWasInifite or NumberWasTooBig */
FinalTypeMask = 0xff
};
typedef struct ConversionStatus {
CborTag lastTag;
uint64_t originalNumber;
int flags;
} ConversionStatus;
static CborError value_to_json(FILE *out, CborValue *it, int flags, CborType type, ConversionStatus *status);
static CborError dump_bytestring_base16(char **result, CborValue *it)
{
static const char characters[] = "0123456789abcdef";
size_t i;
size_t n = 0;
uint8_t *buffer;
CborError err = cbor_value_calculate_string_length(it, &n);
if (err)
return err;
/* a Base16 (hex) output is twice as big as our buffer */
buffer = (uint8_t *)malloc(n * 2 + 1);
if (buffer == NULL)
/* out of memory */
return CborErrorOutOfMemory;
*result = (char *)buffer;
/* let cbor_value_copy_byte_string know we have an extra byte for the terminating NUL */
++n;
err = cbor_value_copy_byte_string(it, buffer + n - 1, &n, it);
cbor_assert(err == CborNoError);
for (i = 0; i < n; ++i) {
uint8_t byte = buffer[n + i];
buffer[2*i] = characters[byte >> 4];
buffer[2*i + 1] = characters[byte & 0xf];
}
return CborNoError;
}
static CborError generic_dump_base64(char **result, CborValue *it, const char alphabet[65])
{
size_t n = 0, i;
uint8_t *buffer, *out, *in;
CborError err = cbor_value_calculate_string_length(it, &n);
if (err)
return err;
/* a Base64 output (untruncated) has 4 bytes for every 3 in the input */
size_t len = (n + 5) / 3 * 4;
buffer = (uint8_t *)malloc(len + 1);
if (buffer == NULL)
/* out of memory */
return CborErrorOutOfMemory;
out = buffer;
*result = (char *)buffer;
/* we read our byte string at the tail end of the buffer
* so we can do an in-place conversion while iterating forwards */
in = buffer + len - n;
/* let cbor_value_copy_byte_string know we have an extra byte for the terminating NUL */
++n;
err = cbor_value_copy_byte_string(it, in, &n, it);
cbor_assert(err == CborNoError);
uint_least32_t val = 0;
for (i = 0; n - i >= 3; i += 3) {
/* read 3 bytes x 8 bits = 24 bits */
if (false) {
#ifdef __GNUC__
} else if (i) {
__builtin_memcpy(&val, in + i - 1, sizeof(val));
val = cbor_ntohl(val);
#endif
} else {
val = (in[i] << 16) | (in[i + 1] << 8) | in[i + 2];
}
/* write 4 chars x 6 bits = 24 bits */
*out++ = alphabet[(val >> 18) & 0x3f];
*out++ = alphabet[(val >> 12) & 0x3f];
*out++ = alphabet[(val >> 6) & 0x3f];
*out++ = alphabet[val & 0x3f];
}
/* maybe 1 or 2 bytes left */
if (n - i) {
/* we can read in[i + 1] even if it's past the end of the string because
* we know (by construction) that it's a NUL byte */
#ifdef __GNUC__
uint16_t val16;
__builtin_memcpy(&val16, in + i, sizeof(val16));
val = cbor_ntohs(val16);
#else
val = (in[i] << 8) | in[i + 1];
#endif
val <<= 8;
/* the 65th character in the alphabet is our filler: either '=' or '\0' */
out[4] = '\0';
out[3] = alphabet[64];
if (n - i == 2) {
/* write the third char in 3 chars x 6 bits = 18 bits */
out[2] = alphabet[(val >> 6) & 0x3f];
} else {
out[2] = alphabet[64]; /* filler */
}
out[1] = alphabet[(val >> 12) & 0x3f];
out[0] = alphabet[(val >> 18) & 0x3f];
} else {
out[0] = '\0';
}
return CborNoError;
}
static CborError dump_bytestring_base64(char **result, CborValue *it)
{
static const char alphabet[] = "ABCDEFGH" "IJKLMNOP" "QRSTUVWX" "YZabcdef"
"ghijklmn" "opqrstuv" "wxyz0123" "456789+/" "=";
return generic_dump_base64(result, it, alphabet);
}
static CborError dump_bytestring_base64url(char **result, CborValue *it)
{
static const char alphabet[] = "ABCDEFGH" "IJKLMNOP" "QRSTUVWX" "YZabcdef"
"ghijklmn" "opqrstuv" "wxyz0123" "456789-_";
return generic_dump_base64(result, it, alphabet);
}
static CborError add_value_metadata(FILE *out, CborType type, const ConversionStatus *status)
{
int flags = status->flags;
if (flags & TypeWasTagged) {
/* extract the tagged type, which may be JSON native */
type = flags & FinalTypeMask;
flags &= ~(FinalTypeMask | TypeWasTagged);
if (fprintf(out, "\"tag\":\"%" PRIu64 "\"%s", status->lastTag,
flags & ~TypeWasTagged ? "," : "") < 0)
return CborErrorIO;
}
if (!flags)
return CborNoError;
/* print at least the type */
if (fprintf(out, "\"t\":%d", type) < 0)
return CborErrorIO;
if (flags & NumberWasNaN)
if (fprintf(out, ",\"v\":\"nan\"") < 0)
return CborErrorIO;
if (flags & NumberWasInfinite)
if (fprintf(out, ",\"v\":\"%sinf\"", flags & NumberWasNegative ? "-" : "") < 0)
return CborErrorIO;
if (flags & NumberPrecisionWasLost)
if (fprintf(out, ",\"v\":\"%c%" PRIx64 "\"", flags & NumberWasNegative ? '-' : '+',
status->originalNumber) < 0)
return CborErrorIO;
if (type == CborSimpleType)
if (fprintf(out, ",\"v\":%d", (int)status->originalNumber) < 0)
return CborErrorIO;
return CborNoError;
}
static CborError find_tagged_type(CborValue *it, CborTag *tag, CborType *type)
{
CborError err = CborNoError;
*type = cbor_value_get_type(it);
while (*type == CborTagType) {
cbor_value_get_tag(it, tag); /* can't fail */
err = cbor_value_advance_fixed(it);
if (err)
return err;
*type = cbor_value_get_type(it);
}
return err;
}
static CborError tagged_value_to_json(FILE *out, CborValue *it, int flags, ConversionStatus *status)
{
CborTag tag;
CborError err;
if (flags & CborConvertTagsToObjects) {
cbor_value_get_tag(it, &tag); /* can't fail */
err = cbor_value_advance_fixed(it);
if (err)
return err;
if (fprintf(out, "{\"tag%" PRIu64 "\":", tag) < 0)
return CborErrorIO;
CborType type = cbor_value_get_type(it);
err = value_to_json(out, it, flags, type, status);
if (err)
return err;
if (flags & CborConvertAddMetadata && status->flags) {
if (fprintf(out, ",\"tag%" PRIu64 "$cbor\":{", tag) < 0 ||
add_value_metadata(out, type, status) != CborNoError ||
fputc('}', out) < 0)
return CborErrorIO;
}
if (fputc('}', out) < 0)
return CborErrorIO;
status->flags = TypeWasNotNative | CborTagType;
return CborNoError;
}
CborType type;
err = find_tagged_type(it, &status->lastTag, &type);
if (err)
return err;
tag = status->lastTag;
/* special handling of byte strings? */
if (type == CborByteStringType && (flags & CborConvertByteStringsToBase64Url) == 0 &&
(tag == CborNegativeBignumTag || tag == CborExpectedBase16Tag || tag == CborExpectedBase64Tag)) {
char *str;
const char *pre = "";
if (tag == CborNegativeBignumTag) {
pre = "~";
err = dump_bytestring_base64url(&str, it);
} else if (tag == CborExpectedBase64Tag) {
err = dump_bytestring_base64(&str, it);
} else { /* tag == CborExpectedBase16Tag */
err = dump_bytestring_base16(&str, it);
}
if (err)
return err;
err = fprintf(out, "\"%s%s\"", pre, str) < 0 ? CborErrorIO : CborNoError;
free(str);
status->flags = TypeWasNotNative | TypeWasTagged | CborByteStringType;
return err;
}
/* no special handling */
err = value_to_json(out, it, flags, type, status);
status->flags |= TypeWasTagged | type;
return err;
}
static CborError stringify_map_key(char **key, CborValue *it, int flags, CborType type)
{
(void)flags; /* unused */
(void)type; /* unused */
#ifdef WITHOUT_OPEN_MEMSTREAM
(void)key; /* unused */
(void)it; /* unused */
return CborErrorJsonNotImplemented;
#else
size_t size;
FILE *memstream = open_memstream(key, &size);
if (memstream == NULL)
return CborErrorOutOfMemory; /* could also be EMFILE, but it's unlikely */
CborError err = cbor_value_to_pretty_advance(memstream, it);
if (unlikely(fclose(memstream) < 0 || *key == NULL))
return CborErrorInternalError;
return err;
#endif
}
static CborError array_to_json(FILE *out, CborValue *it, int flags, ConversionStatus *status)
{
const char *comma = "";
while (!cbor_value_at_end(it)) {
if (fprintf(out, "%s", comma) < 0)
return CborErrorIO;
comma = ",";
CborError err = value_to_json(out, it, flags, cbor_value_get_type(it), status);
if (err)
return err;
}
return CborNoError;
}
static CborError map_to_json(FILE *out, CborValue *it, int flags, ConversionStatus *status)
{
const char *comma = "";
CborError err;
while (!cbor_value_at_end(it)) {
char *key;
if (fprintf(out, "%s", comma) < 0)
return CborErrorIO;
comma = ",";
CborType keyType = cbor_value_get_type(it);
if (likely(keyType == CborTextStringType)) {
size_t n = 0;
err = cbor_value_dup_text_string(it, &key, &n, it);
} else if (flags & CborConvertStringifyMapKeys) {
err = stringify_map_key(&key, it, flags, keyType);
} else {
return CborErrorJsonObjectKeyNotString;
}
if (err)
return err;
/* first, print the key */
if (fprintf(out, "\"%s\":", key) < 0) {
free(key);
return CborErrorIO;
}
/* then, print the value */
CborType valueType = cbor_value_get_type(it);
err = value_to_json(out, it, flags, valueType, status);
/* finally, print any metadata we may have */
if (flags & CborConvertAddMetadata) {
if (!err && keyType != CborTextStringType) {
if (fprintf(out, ",\"%s$keycbordump\":true", key) < 0)
err = CborErrorIO;
}
if (!err && status->flags) {
if (fprintf(out, ",\"%s$cbor\":{", key) < 0 ||
add_value_metadata(out, valueType, status) != CborNoError ||
fputc('}', out) < 0)
err = CborErrorIO;
}
}
free(key);
if (err)
return err;
}
return CborNoError;
}
static CborError value_to_json(FILE *out, CborValue *it, int flags, CborType type, ConversionStatus *status)
{
CborError err;
status->flags = 0;
switch (type) {
case CborArrayType:
case CborMapType: {
/* recursive type */
CborValue recursed;
err = cbor_value_enter_container(it, &recursed);
if (err) {
copy_current_position(it, &recursed);
return err; /* parse error */
}
if (fputc(type == CborArrayType ? '[' : '{', out) < 0)
return CborErrorIO;
err = (type == CborArrayType) ?
array_to_json(out, &recursed, flags, status) :
map_to_json(out, &recursed, flags, status);
if (err) {
copy_current_position(it, &recursed);
return err; /* parse error */
}
if (fputc(type == CborArrayType ? ']' : '}', out) < 0)
return CborErrorIO;
err = cbor_value_leave_container(it, &recursed);
if (err)
return err; /* parse error */
status->flags = 0; /* reset, there are never conversion errors for us */
return CborNoError;
}
case CborIntegerType: {
double num; /* JS numbers are IEEE double precision */
uint64_t val;
cbor_value_get_raw_integer(it, &val); /* can't fail */
num = (double)val;
if (cbor_value_is_negative_integer(it)) {
num = -num - 1; /* convert to negative */
if ((uint64_t)(-num - 1) != val) {
status->flags = NumberPrecisionWasLost | NumberWasNegative;
status->originalNumber = val;
}
} else {
if ((uint64_t)num != val) {
status->flags = NumberPrecisionWasLost;
status->originalNumber = val;
}
}
if (fprintf(out, "%.0f", num) < 0) /* this number has no fraction, so no decimal points please */
return CborErrorIO;
break;
}
case CborByteStringType:
case CborTextStringType: {
char *str;
if (type == CborByteStringType) {
err = dump_bytestring_base64url(&str, it);
status->flags = TypeWasNotNative;
} else {
size_t n = 0;
err = cbor_value_dup_text_string(it, &str, &n, it);
}
if (err)
return err;
err = (fprintf(out, "\"%s\"", str) < 0) ? CborErrorIO : CborNoError;
free(str);
return err;
}
case CborTagType:
return tagged_value_to_json(out, it, flags, status);
case CborSimpleType: {
uint8_t simple_type;
cbor_value_get_simple_type(it, &simple_type); /* can't fail */
status->flags = TypeWasNotNative;
status->originalNumber = simple_type;
if (fprintf(out, "\"simple(%" PRIu8 ")\"", simple_type) < 0)
return CborErrorIO;
break;
}
case CborNullType:
if (fprintf(out, "null") < 0)
return CborErrorIO;
break;
case CborUndefinedType:
status->flags = TypeWasNotNative;
if (fprintf(out, "\"undefined\"") < 0)
return CborErrorIO;
break;
case CborBooleanType: {
bool val;
cbor_value_get_boolean(it, &val); /* can't fail */
if (fprintf(out, val ? "true" : "false") < 0)
return CborErrorIO;
break;
}
#ifndef CBOR_NO_FLOATING_POINT
case CborDoubleType: {
double val;
if (false) {
float f;
case CborFloatType:
status->flags = TypeWasNotNative;
cbor_value_get_float(it, &f);
val = f;
} else if (false) {
uint16_t f16;
case CborHalfFloatType:
# ifndef CBOR_NO_HALF_FLOAT_TYPE
status->flags = TypeWasNotNative;
cbor_value_get_half_float(it, &f16);
val = decode_half(f16);
# else
(void)f16;
err = CborErrorUnsupportedType;
break;
# endif
} else {
cbor_value_get_double(it, &val);
}
int r = fpclassify(val);
if (r == FP_NAN || r == FP_INFINITE) {
if (fprintf(out, "null") < 0)
return CborErrorIO;
status->flags |= r == FP_NAN ? NumberWasNaN :
NumberWasInfinite | (val < 0 ? NumberWasNegative : 0);
} else {
uint64_t ival = (uint64_t)fabs(val);
if ((double)ival == fabs(val)) {
/* print as integer so we get the full precision */
r = fprintf(out, "%s%" PRIu64, val < 0 ? "-" : "", ival);
status->flags |= TypeWasNotNative; /* mark this integer number as a double */
} else {
/* this number is definitely not a 64-bit integer */
r = fprintf(out, "%." DBL_DECIMAL_DIG_STR "g", val);
}
if (r < 0)
return CborErrorIO;
}
break;
}
#else
case CborDoubleType:
case CborFloatType:
case CborHalfFloatType:
err = CborErrorUnsupportedType;
break;
#endif /* !CBOR_NO_FLOATING_POINT */
case CborInvalidType:
return CborErrorUnknownType;
}
return cbor_value_advance_fixed(it);
}
/**
* \enum CborToJsonFlags
* The CborToJsonFlags enum contains flags that control the conversion of CBOR to JSON.
*
* \value CborConvertAddMetadata Adds metadata to facilitate restoration of the original CBOR data.
* \value CborConvertTagsToObjects Converts CBOR tags to JSON objects
* \value CborConvertIgnoreTags (default) Ignore CBOR tags, except for byte strings
* \value CborConvertObeyByteStringTags (default) Honor formatting of CBOR byte strings if so tagged
* \value CborConvertByteStringsToBase64Url Force the conversion of all CBOR byte strings to Base64url encoding, despite any tags
* \value CborConvertRequireMapStringKeys (default) Require CBOR map keys to be strings, failing the conversion if they are not
* \value CborConvertStringifyMapKeys Convert non-string keys in CBOR maps to a string form
* \value CborConvertDefaultFlags Default conversion flags.
*/
/**
* \fn CborError cbor_value_to_json(FILE *out, const CborValue *value, int flags)
*
* Converts the current CBOR type pointed to by \a value to JSON and writes that
* to the \a out stream. If an error occurs, this function returns an error
* code similar to CborParsing. The \a flags parameter indicates one or more of
* the flags from CborToJsonFlags that control the conversion.
*
* \sa cbor_value_to_json_advance(), cbor_value_to_pretty()
*/
/**
* Converts the current CBOR type pointed to by \a value to JSON and writes that
* to the \a out stream. If an error occurs, this function returns an error
* code similar to CborParsing. The \a flags parameter indicates one or more of
* the flags from CborToJsonFlags that control the conversion.
*
* If no error ocurred, this function advances \a value to the next element.
*
* \sa cbor_value_to_json(), cbor_value_to_pretty_advance()
*/
CborError cbor_value_to_json_advance(FILE *out, CborValue *value, int flags)
{
ConversionStatus status;
return value_to_json(out, value, flags, cbor_value_get_type(value), &status);
}
/** @} */