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cosmopolitan/third_party/mbedtls/asn1write.c
Justine Tunney ae5d06dc53 Unbloat build config 
- 10.5% reduction of o//depend dependency graph
- 8.8% reduction in latency of make command
- Fix issue with temporary file cleanup

There's a new -w option in compile.com that turns off the recent
Landlock output path workaround for "good commands" which do not
unlink() the output file like GNU tooling does.

Our new GNU Make unveil sandboxing appears to have zero overhead
in the grand scheme of things. Full builds are pretty fast since
the only thing that's actually slowed us down is probably libcxx

    make -j16 MODE=rel
    RL: took 85,732,063µs wall time
    RL: ballooned to 323,612kb in size
    RL: needed 828,560,521µs cpu (11% kernel)
    RL: caused 39,080,670 page faults (99% memcpy)
    RL: 350,073 context switches (72% consensual)
    RL: performed 0 reads and 11,494,960 write i/o operations

pledge() and unveil() no longer consider ENOSYS to be an error.
These functions have also been added to Python's cosmo module.

This change also removes some WIN32 APIs and System Five magnums
which we're not using and it's doubtful anyone else would be too
2022-08-10 04:43:09 -07:00

670 lines
25 KiB
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:4;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright The Mbed TLS Contributors │
│ │
│ Licensed under the Apache License, Version 2.0 (the "License"); │
│ you may not use this file except in compliance with the License. │
│ You may obtain a copy of the License at │
│ │
│ http://www.apache.org/licenses/LICENSE-2.0 │
│ │
│ Unless required by applicable law or agreed to in writing, software │
│ distributed under the License is distributed on an "AS IS" BASIS, │
│ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. │
│ See the License for the specific language governing permissions and │
│ limitations under the License. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/str/str.h"
#include "third_party/mbedtls/asn1write.h"
#include "third_party/mbedtls/common.h"
#include "third_party/mbedtls/error.h"
#include "third_party/mbedtls/platform.h"
asm(".ident\t\"\\n\\n\
Mbed TLS (Apache 2.0)\\n\
Copyright ARM Limited\\n\
Copyright Mbed TLS Contributors\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */
/**
* @fileoverview ASN.1 buffer writing functionality
*/
#if defined(MBEDTLS_ASN1_WRITE_C)
/**
* \brief Write a length field in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param len The length value to write.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
{
if( len < 0x80 )
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = (unsigned char) len;
return( 1 );
}
if( len <= 0xFF )
{
if( *p - start < 2 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = (unsigned char) len;
*--(*p) = 0x81;
return( 2 );
}
if( len <= 0xFFFF )
{
if( *p - start < 3 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = ( len ) & 0xFF;
*--(*p) = ( len >> 8 ) & 0xFF;
*--(*p) = 0x82;
return( 3 );
}
if( len <= 0xFFFFFF )
{
if( *p - start < 4 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = ( len ) & 0xFF;
*--(*p) = ( len >> 8 ) & 0xFF;
*--(*p) = ( len >> 16 ) & 0xFF;
*--(*p) = 0x83;
return( 4 );
}
#if SIZE_MAX > 0xFFFFFFFF
if( len <= 0xFFFFFFFF )
#endif
{
if( *p - start < 5 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = ( len ) & 0xFF;
*--(*p) = ( len >> 8 ) & 0xFF;
*--(*p) = ( len >> 16 ) & 0xFF;
*--(*p) = ( len >> 24 ) & 0xFF;
*--(*p) = 0x84;
return( 5 );
}
#if SIZE_MAX > 0xFFFFFFFF
return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
#endif
}
/**
* \brief Write an ASN.1 tag in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param tag The tag to write.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = tag;
return( 1 );
}
/**
* \brief Write raw buffer data.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param buf The data buffer to write.
* \param size The length of the data buffer.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
const unsigned char *buf, size_t size )
{
size_t len = 0;
if( *p < start || (size_t)( *p - start ) < size )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
len = size;
(*p) -= len;
memcpy( *p, buf, len );
return( (int) len );
}
#if defined(MBEDTLS_BIGNUM_C)
/**
* \brief Write a arbitrary-precision number (#MBEDTLS_ASN1_INTEGER)
* in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param X The MPI to write.
* It must be non-negative.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
// Write the MPI
//
len = mbedtls_mpi_size( X );
if( *p < start || (size_t)( *p - start ) < len )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
(*p) -= len;
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
// DER format assumes 2s complement for numbers, so the leftmost bit
// should be 0 for positive numbers and 1 for negative numbers.
//
if( X->s ==1 && **p & 0x80 )
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = 0x00;
len += 1;
}
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
ret = (int) len;
cleanup:
return( ret );
}
#endif /* MBEDTLS_BIGNUM_C */
/**
* \brief Write a NULL tag (#MBEDTLS_ASN1_NULL) with zero data
* in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
// Write NULL
//
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
return( (int) len );
}
/**
* \brief Write an OID tag (#MBEDTLS_ASN1_OID) and data
* in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param oid The OID to write.
* \param oid_len The length of the OID.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
const char *oid, size_t oid_len )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
(const unsigned char *) oid, oid_len ) );
MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
return( (int) len );
}
/**
* \brief Write an AlgorithmIdentifier sequence in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param oid The OID of the algorithm to write.
* \param oid_len The length of the algorithm's OID.
* \param par_len The length of the parameters, which must be already written.
* If 0, NULL parameters are added
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
const char *oid, size_t oid_len,
size_t par_len )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
if( par_len == 0 )
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
else
len += par_len;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
return( (int) len );
}
/**
* \brief Write a boolean tag (#MBEDTLS_ASN1_BOOLEAN) and value
* in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param boolean The boolean value to write, either \c 0 or \c 1.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = (boolean) ? 255 : 0;
len++;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
return( (int) len );
}
static int asn1_write_tagged_int( unsigned char **p, unsigned char *start, int val, int tag )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
do
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
len += 1;
*--(*p) = val & 0xff;
val >>= 8;
}
while( val > 0 );
if( **p & 0x80 )
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = 0x00;
len += 1;
}
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) );
return( (int) len );
}
/**
* \brief Write an int tag (#MBEDTLS_ASN1_INTEGER) and value
* in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param val The integer value to write.
* It must be non-negative.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
{
return( asn1_write_tagged_int( p, start, val, MBEDTLS_ASN1_INTEGER ) );
}
/**
* \brief Write an enum tag (#MBEDTLS_ASN1_ENUMERATED) and value
* in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param val The integer value to write.
*
* \return The number of bytes written to \p p on success.
* \return A negative \c MBEDTLS_ERR_ASN1_XXX error code on failure.
*/
int mbedtls_asn1_write_enum( unsigned char **p, unsigned char *start, int val )
{
return( asn1_write_tagged_int( p, start, val, MBEDTLS_ASN1_ENUMERATED ) );
}
/**
* \brief Write a string in ASN.1 format using a specific
* string encoding tag.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param tag The string encoding tag to write, e.g.
* #MBEDTLS_ASN1_UTF8_STRING.
* \param text The string to write.
* \param text_len The length of \p text in bytes (which might
* be strictly larger than the number of characters).
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_tagged_string( unsigned char **p, unsigned char *start,
int tag, const char *text, size_t text_len )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
(const unsigned char *) text, text_len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) );
return( (int) len );
}
/**
* \brief Write a UTF8 string in ASN.1 format using the UTF8String
* string encoding tag (#MBEDTLS_ASN1_UTF8_STRING).
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param text The string to write.
* \param text_len The length of \p text in bytes (which might
* be strictly larger than the number of characters).
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start,
const char *text, size_t text_len )
{
return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len) );
}
/**
* \brief Write a string in ASN.1 format using the PrintableString
* string encoding tag (#MBEDTLS_ASN1_PRINTABLE_STRING).
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param text The string to write.
* \param text_len The length of \p text in bytes (which might
* be strictly larger than the number of characters).
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
const char *text, size_t text_len )
{
return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, text_len) );
}
/**
* \brief Write a string in ASN.1 format using the IA5String
* string encoding tag (#MBEDTLS_ASN1_IA5_STRING).
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param text The string to write.
* \param text_len The length of \p text in bytes (which might
* be strictly larger than the number of characters).
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
const char *text, size_t text_len )
{
return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len) );
}
/**
* \brief This function writes a named bitstring tag
* (#MBEDTLS_ASN1_BIT_STRING) and value in ASN.1 format.
*
* As stated in RFC 5280 Appendix B, trailing zeroes are
* omitted when encoding named bitstrings in DER.
*
* \note This function works backwards within the data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer which is used for bounds-checking.
* \param buf The bitstring to write.
* \param bits The total number of bits in the bitstring.
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_named_bitstring( unsigned char **p,
unsigned char *start,
const unsigned char *buf,
size_t bits )
{
size_t unused_bits, byte_len;
const unsigned char *cur_byte;
unsigned char cur_byte_shifted;
unsigned char bit;
byte_len = ( bits + 7 ) / 8;
unused_bits = ( byte_len * 8 ) - bits;
/*
* Named bitstrings require that trailing 0s are excluded in the encoding
* of the bitstring. Trailing 0s are considered part of the 'unused' bits
* when encoding this value in the first content octet
*/
if( bits )
{
cur_byte = buf + byte_len - 1;
cur_byte_shifted = *cur_byte >> unused_bits;
for( ; ; )
{
bit = cur_byte_shifted & 0x1;
cur_byte_shifted >>= 1;
if( bit )
break;
bits--;
if( bits == 0 )
break;
if( bits % 8 == 0 )
cur_byte_shifted = *--cur_byte;
}
}
return( mbedtls_asn1_write_bitstring( p, start, buf, bits ) );
}
/**
* \brief Write a bitstring tag (#MBEDTLS_ASN1_BIT_STRING) and
* value in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param buf The bitstring to write.
* \param bits The total number of bits in the bitstring.
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
const unsigned char *buf, size_t bits )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
size_t unused_bits, byte_len;
byte_len = ( bits + 7 ) / 8;
unused_bits = ( byte_len * 8 ) - bits;
if( *p < start || (size_t)( *p - start ) < byte_len + 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
len = byte_len + 1;
/* Write the bitstring. Ensure the unused bits are zeroed */
if( byte_len > 0 )
{
byte_len--;
*--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 );
( *p ) -= byte_len;
memcpy( *p, buf, byte_len );
}
/* Write unused bits */
*--( *p ) = (unsigned char)unused_bits;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
return( (int) len );
}
/**
* \brief Write an octet string tag (#MBEDTLS_ASN1_OCTET_STRING)
* and value in ASN.1 format.
*
* \note This function works backwards in data buffer.
*
* \param p The reference to the current position pointer.
* \param start The start of the buffer, for bounds-checking.
* \param buf The buffer holding the data to write.
* \param size The length of the data buffer \p buf.
*
* \return The number of bytes written to \p p on success.
* \return A negative error code on failure.
*/
int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
const unsigned char *buf, size_t size )
{
int ret = MBEDTLS_ERR_THIS_CORRUPTION;
size_t len = 0;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
return( (int) len );
}
/* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(),
* which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */
static mbedtls_asn1_named_data *asn1_find_named_data(
mbedtls_asn1_named_data *list,
const char *oid, size_t len )
{
while( list )
{
if( list->oid.len == len &&
timingsafe_bcmp( list->oid.p, oid, len ) == 0 )
{
break;
}
list = list->next;
}
return( list );
}
/**
* \brief Create or find a specific named_data entry for writing in a
* sequence or list based on the OID. If not already in there,
* a new entry is added to the head of the list.
* Warning: Destructive behaviour for the val data!
*
* \param list The pointer to the location of the head of the list to seek
* through (will be updated in case of a new entry).
* \param oid The OID to look for.
* \param oid_len The size of the OID.
* \param val The associated data to store. If this is \c NULL,
* no data is copied to the new or existing buffer.
* \param val_len The minimum length of the data buffer needed.
* If this is 0, do not allocate a buffer for the associated
* data.
* If the OID was already present, enlarge, shrink or free
* the existing buffer to fit \p val_len.
*
* \return A pointer to the new / existing entry on success.
* \return \c NULL if if there was a memory allocation error.
*/
mbedtls_asn1_named_data *mbedtls_asn1_store_named_data(mbedtls_asn1_named_data **head,
const char *oid, size_t oid_len,
const unsigned char *val,
size_t val_len )
{
mbedtls_asn1_named_data *cur;
if( ( cur = asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
{
// Add new entry if not present yet based on OID
//
cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
sizeof(mbedtls_asn1_named_data) );
if( !cur )
return( NULL );
cur->oid.len = oid_len;
cur->oid.p = mbedtls_calloc( 1, oid_len );
if( !cur->oid.p )
{
mbedtls_free( cur );
return( NULL );
}
memcpy( cur->oid.p, oid, oid_len );
cur->val.len = val_len;
if( val_len )
{
cur->val.p = mbedtls_calloc( 1, val_len );
if( !cur->val.p )
{
mbedtls_free( cur->oid.p );
mbedtls_free( cur );
return( NULL );
}
}
cur->next = *head;
*head = cur;
}
else if( val_len == 0 )
{
mbedtls_free( cur->val.p );
cur->val.p = NULL;
}
else if( cur->val.len != val_len )
{
/*
* Enlarge existing value buffer if needed
* Preserve old data until the allocation succeeded, to leave list in
* a consistent state in case allocation fails.
*/
void *p = mbedtls_calloc( 1, val_len );
if( !p )
return( NULL );
mbedtls_free( cur->val.p );
cur->val.p = p;
cur->val.len = val_len;
}
if( val )
memcpy( cur->val.p, val, val_len );
return( cur );
}
#endif /* MBEDTLS_ASN1_WRITE_C */
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