Re: [PATCH v4 4/8] crypto: add ASN.1 decoder

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Apr 11, 2022 at 06:43:23PM +0800, zhenwei pi wrote:
> From: Lei He <helei.sig11@bytedance.com>
> 
> Add an ANS.1 decoder which is used to parse asymmetric
> cipher keys
> 
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> Signed-off-by: Lei He <helei.sig11@bytedance.com>
> ---
>  crypto/asn1_decoder.c                 | 161 ++++++++++++++
>  crypto/asn1_decoder.h                 |  75 +++++++
>  crypto/meson.build                    |   1 +
>  tests/unit/meson.build                |   1 +
>  tests/unit/test-crypto-asn1-decoder.c | 289 ++++++++++++++++++++++++++
>  5 files changed, 527 insertions(+)
>  create mode 100644 crypto/asn1_decoder.c
>  create mode 100644 crypto/asn1_decoder.h
>  create mode 100644 tests/unit/test-crypto-asn1-decoder.c
> 
> diff --git a/crypto/asn1_decoder.c b/crypto/asn1_decoder.c
> new file mode 100644
> index 0000000000..506487f713
> --- /dev/null
> +++ b/crypto/asn1_decoder.c

Lets rename this to simply 'der.c' since the DER format is just one
way ASN1 can be encoded, and we only care about DER.

> @@ -0,0 +1,161 @@
> +/*
> + * QEMU Crypto ASN.1 decoder
> + *
> + * Copyright (c) 2022 Bytedance
> + * Author: lei he <helei.sig11@bytedance.com>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#include <stdint.h>
> +#include <stddef.h>
> +
> +#include "crypto/asn1_decoder.h"
> +
> +enum der_type_tag {

QCryptoDERTypeTag

> +    der_type_tag_bool = 0x1,

QCRYPTO_DER_TYPE_TAG_XXXX  for each constant

> +    der_type_tag_int = 0x2,
> +    der_type_tag_bit_str = 0x3,
> +    der_type_tag_oct_str = 0x4,
> +    der_type_tag_oct_null = 0x5,
> +    der_type_tag_oct_oid = 0x6,
> +    der_type_tag_seq = 0x10,
> +    der_type_tag_set = 0x11,
> +};
> +
> +#define DER_CONSTRUCTED_MASK 0x20
> +#define DER_SHORT_LEN_MASK 0x80

QCRYPTO_DER_ as the name prefix for constants.

> +
> +static uint8_t der_peek_byte(const uint8_t **data, size_t *dlen)

'qcrypto_der_' as the name prefix for all methods


> +{
> +    return **data;
> +}
> +
> +static void der_cut_nbytes(const uint8_t **data, size_t *dlen,
> +                           size_t nbytes)
> +{
> +    *data += nbytes;
> +    *dlen -= nbytes;
> +}
> +
> +static uint8_t der_cut_byte(const uint8_t **data, size_t *dlen)
> +{
> +    uint8_t val = der_peek_byte(data, dlen);
> +
> +    der_cut_nbytes(data, dlen, 1);
> +
> +    return val;
> +}
> +
> +static int der_invoke_callback(DERDecodeCb cb, void *ctx,
> +                           const uint8_t *value, size_t vlen)

Make sure the 'const uint8_t' is vertically aligned with
the 'DERDecodeCb'

> +{
> +    if (!cb) {
> +        return 0;
> +    }
> +
> +    return cb(ctx, value, vlen);
> +}
> +
> +static int der_extract_definite_data(const uint8_t **data, size_t *dlen,
> +                                     DERDecodeCb cb, void *ctx)
> +{
> +    const uint8_t *value;
> +    size_t vlen = 0;
> +    uint8_t byte_count = der_cut_byte(data, dlen);
> +
> +    /* short format of definite-length */
> +    if (!(byte_count & DER_SHORT_LEN_MASK)) {
> +        if (byte_count > *dlen) {
> +            return -1;
> +        }
> +
> +        value = *data;
> +        vlen = byte_count;
> +        der_cut_nbytes(data, dlen, vlen);
> +
> +        if (der_invoke_callback(cb, ctx, value, vlen)) {
> +            return -1;
> +        }
> +        return vlen;
> +    }
> +
> +    /* Ignore highest bit */
> +    byte_count &= ~DER_SHORT_LEN_MASK;
> +
> +    /*
> +     * size_t is enough to express the length, although the der encoding
> +     * standard supports larger length.
> +     */
> +    if (byte_count > sizeof(size_t)) {
> +        return -1;
> +    }
> +
> +    while (byte_count--) {
> +        vlen <<= 8;
> +        vlen += der_cut_byte(data, dlen);
> +    }
> +
> +    if (vlen > *dlen) {
> +        return -1;
> +    }
> +
> +    value = *data;
> +    der_cut_nbytes(data, dlen, vlen);
> +
> +    if (der_invoke_callback(cb, ctx, value, vlen) != 0) {
> +        return -1;
> +    }
> +    return vlen;
> +}
> +
> +static int der_extract_data(const uint8_t **data, size_t *dlen,
> +                            DERDecodeCb cb, void *ctx)
> +{
> +    uint8_t val = der_peek_byte(data, dlen);
> +
> +    /* must use definite length format */
> +    if (val == DER_SHORT_LEN_MASK) {
> +        return -1;
> +    }
> +
> +    return der_extract_definite_data(data, dlen, cb, ctx);
> +}
> +
> +int der_decode_int(const uint8_t **data, size_t *dlen,
> +                   DERDecodeCb cb, void *ctx)
> +{
> +    uint8_t tag = der_cut_byte(data, dlen);
> +
> +    /* INTEGER must encoded in primitive-form */
> +    if (tag != der_type_tag_int) {
> +        return -1;
> +    }
> +
> +    return der_extract_data(data, dlen, cb, ctx);
> +}
> +
> +int der_decode_seq(const uint8_t **data, size_t *dlen,
> +                   DERDecodeCb cb, void *ctx)
> +{
> +    uint8_t val = der_cut_byte(data, dlen);
> +
> +    /* SEQUENCE must use constructed form */
> +    if (val != (der_type_tag_seq | DER_CONSTRUCTED_MASK)) {
> +        return -1;
> +    }
> +
> +    return der_extract_data(data, dlen, cb, ctx);
> +}
> diff --git a/crypto/asn1_decoder.h b/crypto/asn1_decoder.h
> new file mode 100644
> index 0000000000..e414807af2
> --- /dev/null
> +++ b/crypto/asn1_decoder.h
> @@ -0,0 +1,75 @@
> +/*
> + * Copyright (c) 2022 Bytedance
> + * Author: lei he <helei.sig11@bytedance.com>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#ifndef QCRYPTO_ASN1_DECODER_H
> +#define QCRYPTO_ASN1_DECODER_H
> +
> +/* Simple decoder used to parse DER encoded rsa keys. */
> +
> +/**
> + *  @opaque: user content.
> + *  @value: the starting address of |value| part of 'Tag-Length-Value' pattern.
> + *  @vlen: length of the |value|.
> + */
> +typedef int (*DERDecodeCb) (void *opaque, const uint8_t *value, size_t vlen);

Essentially we want qcrypto_der / QCryptoDer / QCRYPTO_DER as a prefix
for everything as there is too great a chance of 'der' alone clashing
with some other crypto library we're using.

Can you document the return value. If if can return errors, then I
think we need an 'Error **errp' here.

> +
> +/**
> + * der_decode_int:
> + * @data: pointer to address of input data
> + * @dlen: pointer to length of input data
> + * @cb: callback invoked when decode succeed, if cb equals NULL, no
> + * callback will be invoked
> + * @opaque: parameter passed to cb
> + *
> + * Decode integer from DER-encoded data.
> + *
> + * Returns: On success, *data points to rest data, and *dlen
> + * will be set to the rest length of data, if cb is not NULL, must
> + * return 0 to make decode success, at last, the length of the data
> + * part of the decoded INTEGER will be returned. Otherwise, -1 is
> + * returned.
> + */
> +int der_decode_int(const uint8_t **data,
> +                   size_t *dlen,
> +                   DERDecodeCb cb,
> +                   void *opaque);

Since we're returning errors, I think we should have an 'Error **errp'
in this method, and the next, so we can report useful error messages
to the caller.

> +
> +/**
> + * der_decode_seq:
> + *
> + * Decode sequence from DER-encoded data, similar with der_decode_int.
> + *
> + * @data: pointer to address of input data
> + * @dlen: pointer to length of input data
> + * @cb: callback invoked when decode succeed, if cb equals NULL, no
> + * callback will be invoked
> + * @opaque: parameter passed to cb
> + *
> + * Returns: On success, *data points to rest data, and *dlen
> + * will be set to the rest length of data, if cb is not NULL, must
> + * return 0 to make decode success, at last, the length of the data
> + * part of the decoded SEQUENCE will be returned. Otherwise, -1 is
> + * returned.
> + */
> +int der_decode_seq(const uint8_t **data,
> +                   size_t *dlen,
> +                   DERDecodeCb cb,
> +                   void *opaque);
> +
> +#endif  /* QCRYPTO_ASN1_DECODER_H */
> diff --git a/crypto/meson.build b/crypto/meson.build
> index 7647d5e243..57f29d6f74 100644
> --- a/crypto/meson.build
> +++ b/crypto/meson.build
> @@ -2,6 +2,7 @@ crypto_ss.add(genh)
>  crypto_ss.add(files(
>    'afsplit.c',
>    'akcipher.c',
> +  'asn1_decoder.c',
>    'block-luks.c',
>    'block-qcow.c',
>    'block.c',
> diff --git a/tests/unit/meson.build b/tests/unit/meson.build
> index 96b295263e..037ad0a0b9 100644
> --- a/tests/unit/meson.build
> +++ b/tests/unit/meson.build
> @@ -47,6 +47,7 @@ tests = {
>    'ptimer-test': ['ptimer-test-stubs.c', meson.project_source_root() / 'hw/core/ptimer.c'],
>    'test-qapi-util': [],
>    'test-smp-parse': [qom, meson.project_source_root() / 'hw/core/machine-smp.c'],
> +  'test-crypto-asn1-decoder':[crypto],
>  }
>  
>  if have_system or have_tools
> diff --git a/tests/unit/test-crypto-asn1-decoder.c b/tests/unit/test-crypto-asn1-decoder.c
> new file mode 100644
> index 0000000000..16e10b12f9
> --- /dev/null
> +++ b/tests/unit/test-crypto-asn1-decoder.c
> @@ -0,0 +1,289 @@
> +/*
> + * QEMU Crypto akcipher algorithms
> + *
> + * Copyright (c) 2022 Bytedance
> + * Author: lei he <helei@bytedance.com>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "crypto/asn1_decoder.h"
> +
> +/* rsa(512) private key, generated by openssl */
> +static const uint8_t test_rsa512_priv_key[] =
> +    "\x30\x82\x01\x39"      /* SEQUENCE, offset: 0, length: 313 */
> +    "\x02\x01\x00"          /* INTEGER, offset: 4, length: 1 */
> +    "\x02\x41"              /* INTEGER, offset: 7, length: 65 */
> +    "\x00\xb9\xe1\x22\xdb\x56\x2f\xb6\xf7\xf0\x0a\x87\x43\x07\x12\xdb"
> +    "\x6d\xb6\x2b\x41\x8d\x2c\x3c\xa5\xdd\x78\x9a\x8f\xab\x8e\xf2\x4a"
> +    "\xc8\x34\x0c\x12\x4f\x11\x90\xc6\xc2\xa5\xd0\xcd\xfb\xfc\x2c\x95"
> +    "\x56\x82\xdf\x39\xf3\x3b\x1d\x62\x26\x97\xb7\x93\x25\xc7\xec\x7e"
> +    "\xf7"
> +    "\x02\x03\x01\x00\x01"  /* INTEGER, offset: 74, length: 3 */
> +    "\x02\x40"              /* INTEGER, offset: 79, length: 64 */
> +    "\x1e\x80\xfe\xda\x65\xdb\x70\xb8\x61\x91\x28\xbf\x6c\x32\xc1\x05"
> +    "\xd1\x26\x6a\x1c\x83\xcc\xf4\x1f\x53\x42\x72\x1f\x62\x57\x0a\xc4"
> +    "\x66\x76\x30\x87\xb9\xb1\xb9\x6a\x63\xfd\x8f\x3e\xfc\x35\x3f\xd6"
> +    "\x2e\x6c\xc8\x70\x8a\x17\xc1\x28\x6a\xfe\x51\x56\xb3\x92\x6f\x09"
> +    "\x02\x21"              /* INTEGER, offset: 145, length: 33 */
> +    "\x00\xe3\x2e\x2d\x8d\xba\x1c\x34\x4c\x49\x9f\xc1\xa6\xdd\xd7\x13"
> +    "\x8d\x05\x48\xdd\xff\x5c\x30\xbc\x6b\xc4\x18\x9d\xfc\xa2\xd0\x9b"
> +    "\x4d"
> +    "\x02\x21"             /* INTEGER, offset: 180, length: 33 */
> +    "\x00\xd1\x75\xaf\x4b\xc6\x1a\xb0\x98\x14\x42\xae\x33\xf3\x44\xde"
> +    "\x21\xcb\x04\xda\xfb\x1e\x35\x92\xcd\x69\xc0\x83\x06\x83\x8e\x39"
> +    "\x53"
> +    "\x02\x20"             /* INTEGER, offset: 215, length: 32 */
> +    "\x68\x8d\x2a\xf7\xcb\xcc\x09\x21\x86\xcc\x98\x21\xc4\x7c\xa4\x09"
> +    "\xc5\x81\xd8\x71\x1a\x2b\x6f\xbb\xa4\xde\xb3\x6e\xbe\x3b\x85\x0d"
> +    "\x02\x20"             /* INTEGER, offset: 249, length: 32 */
> +    "\x64\x06\x0e\xef\xe0\x6a\x5e\x6a\x41\x42\x96\x6d\xb8\x7d\xea\x95"
> +    "\xb8\x9d\x58\xf5\x12\x38\x03\x22\x94\x9d\x99\xf4\x42\x5e\x68\x81"
> +    "\x02\x20"             /* INTEGER, offset: 283, length: 32 */
> +    "\x7f\x1d\x87\xe8\x55\x30\x75\xc7\x29\xec\xc9\x65\x76\x5a\x6a\xa3"
> +    "\x4a\x6e\xe1\x26\x65\xd1\x76\xd5\xb9\xd1\x8b\xa8\x73\xe2\x6a\x9e";
> +
> +static const uint8_t test_rsa2048_priv_key[] =
> +    "\x30\x82\x04\xa6"          /* SEQUENCE, offset: 0, length 1190 */
> +    "\x02\x01\x00"              /* INTEGER, offset: 4, length: 1 */
> +    "\x02\x82\x01\x01"          /* INTEGER, offset: 7, length: 257 */
> +    "\x00\xd1\x48\xc2\xc1\x1d\x4f\x94\xf2\xbb\x9b\xe2\x2d\xe1\xea\x4c"
> +    "\xce\x41\x72\xe3\x41\x7e\x9d\x91\x85\xa3\x4e\xe1\x2c\xf6\x52\x6d"
> +    "\xf9\x84\x64\xdf\x87\x28\x4a\xc9\x9d\x78\x93\x47\xc8\xd9\x66\x2e"
> +    "\xf4\xc6\xf0\x32\x15\x1a\xe8\xaf\x5a\xca\x3a\xd3\x3e\xf6\xde\x86"
> +    "\xdd\x9b\xa6\x4d\x74\x58\xf0\x11\x7f\x66\xd5\x1c\xd8\xde\xa3\xf8"
> +    "\xa3\xfc\x33\x55\x89\xa9\xc3\xea\x5b\x2e\x31\x06\xf8\xcb\x9e\x6e"
> +    "\xb2\x68\x0d\xe6\xc3\x5c\x2d\xf8\xa2\xbd\x00\x1a\xf6\xb6\xdd\x14"
> +    "\x8d\x11\x6d\x2d\xc6\x0c\x09\xe6\xf6\xb9\x8b\x87\x4c\x9f\x4d\x63"
> +    "\xd3\x94\xf4\x32\xca\xcf\x5e\xbf\xe2\x7f\x73\x5a\x65\xec\x82\x0d"
> +    "\x7f\x30\x25\x03\xd4\x3a\xff\xa2\xe8\xd6\xb5\x1f\x4f\x36\x64\x61"
> +    "\xc3\x5f\xb2\x9e\x0c\x53\x04\x19\x34\x99\xe8\xe3\xe6\xd3\x2f\x45"
> +    "\x58\x8e\x5d\x54\x5a\xa0\xc0\x5e\x51\x9b\x22\x15\xec\x26\x6f\x72"
> +    "\x68\xe9\xbf\x5d\x1d\xb5\xd9\xe4\x81\x1a\x92\x66\xa8\xcb\x73\x46"
> +    "\xab\x96\x7b\xf8\x9c\xf5\xb5\x9e\x2b\x13\x71\xe0\x01\x0c\x59\x1b"
> +    "\x63\x9f\xb7\xd1\xcd\x47\x8e\xc7\x3a\xbe\xcb\x47\xa7\x23\x43\xa7"
> +    "\x7d\xbd\x2c\x4e\x22\x37\xcc\xf9\x1b\x1b\xbb\xed\xec\xf0\x47\x92"
> +    "\x43"
> +    "\x02\x03\x01\x00\x01"      /* INTEGER, offset 268, length 3 */
> +    "\x02\x82\x01\x01"          /* INTEGER, offset 273, length 257 */
> +    "\x00\x8d\x21\x97\x0c\x29\x9a\xf8\x23\xf4\x76\x3b\xc1\x9b\x3e\xa8"
> +    "\x8a\xd2\xc2\x0a\x14\xa9\xb0\xd2\x68\x9f\x67\x5b\x1c\x3a\x03\xfe"
> +    "\x5b\xac\x77\x65\xf1\xbc\x2f\x2a\xe5\x01\x61\xb8\x9f\xee\x53\x25"
> +    "\x49\x36\x3a\xd6\x5b\x3b\x29\x3c\xcf\x69\xde\xdf\x83\xef\x70\xc2"
> +    "\xdc\x00\xd1\xd6\x1b\xa6\xba\x45\xe2\x77\x53\x31\xbf\xe1\xec\x0b"
> +    "\x89\x72\x52\x9f\xd5\x54\xe1\x64\x52\x16\xc5\x43\x21\x56\x16\xc2"
> +    "\x29\x97\x58\x00\x8d\x2f\xc5\x64\x8d\x42\x0d\x27\x21\xc6\xd1\x31"
> +    "\xc1\xab\xc5\xc7\x7f\x6d\xb0\xe3\xca\xef\xf6\xf2\xc7\xae\x09\xbf"
> +    "\x4d\xc0\x4e\x90\x2c\x28\xb9\xcc\x22\x74\xf2\xd5\xff\x4d\x86\xf6"
> +    "\xec\x45\x1f\xbf\x25\x4c\x30\x26\x76\x4f\x09\x13\x83\xef\x35\x73"
> +    "\xa3\xa2\xb1\x40\xcf\x07\x7a\x83\xae\xea\x00\xea\x74\xc7\x54\x6a"
> +    "\x88\x19\xed\x35\xd3\x7e\x5e\xac\x51\xc1\x1e\x5e\x2c\x57\x72\x20"
> +    "\x10\x6a\x0c\x47\xe1\xf0\x36\x70\xd2\xa7\x57\x64\x47\x46\x9f\xca"
> +    "\x23\x8a\x48\x50\x1d\x33\x6a\x86\x46\x69\xed\x54\x65\x6b\x9e\xab"
> +    "\x1f\x84\x87\xf4\x92\x8a\x6c\x44\x20\xaa\x8d\xd8\x50\xde\x45\x74"
> +    "\xe0\xa8\xc7\xb9\x38\x74\x24\x51\x33\xf0\x39\x54\x6c\x11\xae\xc2"
> +    "\x29"
> +    "\x02\x81\x81"              /* INTEGER, offset 534, length 129 */
> +    "\x00\xe8\x26\xd1\xf9\xa0\xd3\x0e\x3f\x2f\x89\x9b\x94\x16\x12\xd1"
> +    "\xae\x3c\x53\x9c\xcf\xc6\xf7\x03\xf5\xdf\x39\xdc\x25\x5d\xcb\xb8"
> +    "\xb9\x74\x3e\x3b\x36\xf6\xa0\x8d\xb1\x0e\xd8\xfe\x8c\xcd\x01\x13"
> +    "\x77\x73\x08\x0f\x32\xbd\xe6\x95\xdc\xd0\x14\x7d\x44\xdc\x3e\xd9"
> +    "\xaa\x8a\x32\xe6\x0e\x76\xb6\x05\xc5\x6b\x87\x78\x9a\x32\xe2\xf8"
> +    "\x78\xba\x58\x75\x58\xd5\x26\x9d\x9a\x0f\xb6\xca\xb5\x27\xd8\x58"
> +    "\xae\x3f\x49\x54\xd2\x2b\xac\x28\x39\x88\x31\x42\x12\x08\xea\x0b"
> +    "\x39\x58\xae\xf3\x82\xa0\xe2\x75\x7c\x96\xa9\xb8\x57\x29\x6d\xd7"
> +    "\x37"
> +    "\x02\x81\x81"              /* INTEGER, offset 666, length 129 */
> +    "\x00\xe6\xc8\x91\x50\x49\x97\x56\x70\x6e\x25\xf5\x77\x25\xa5\x41"
> +    "\xfe\xd7\x25\x1b\xc1\x4a\xff\x37\x44\x2b\x46\xa0\xdf\xe8\x02\x09"
> +    "\xdd\xa8\x41\xa1\x12\x84\x3c\xf8\xc2\x13\x3e\xb8\x4b\x22\x01\xac"
> +    "\xa6\x09\xb2\xe9\xcd\xc8\x51\xee\xde\xa3\x1e\x6b\xfe\xb1\xf8\xb6"
> +    "\x9e\x48\x36\x62\x0b\x05\xfa\x38\xc1\x06\x04\x58\x95\x4d\x25\x13"
> +    "\x6d\x0b\x12\x0b\xc9\x6d\x59\xfc\x33\x03\x36\x01\x12\x09\x72\x74"
> +    "\x5e\x98\x65\x66\x2f\x3a\xde\xd8\xd4\xee\x6f\x82\xe6\x36\x49\x12"
> +    "\x6a\x94\x28\xe9\x28\x9e\xef\x29\xdc\xdf\xab\x94\x65\x02\x4e\x4b"
> +    "\x55"
> +    "\x02\x81\x81"              /* INTEGER, offset 798, length 129 */
> +    "\x00\xc9\xda\xb7\x48\x6e\x66\x15\x45\x2b\x78\x63\x26\x67\xeb\x05"
> +    "\x16\x92\xad\xc0\xf3\x88\xf4\xcf\x24\xc2\x6b\xf4\xd7\x28\xaf\x32"
> +    "\x77\x4e\x73\xad\xd9\x24\xa8\x85\x8b\x26\x75\xd7\x1f\x66\x41\x41"
> +    "\x43\xe3\x69\x66\x8d\xa0\x41\x16\x9d\x60\xef\xef\xdc\x28\x05\x1e"
> +    "\x0e\x03\x0c\x2e\xac\xf4\xdb\x60\x39\x40\x3e\x12\xc7\x40\xe7\xc9"
> +    "\x54\x6f\xf2\xea\x55\xcb\x40\x40\x58\xec\xc0\xeb\x90\x88\x8c\xbc"
> +    "\xcf\x05\x88\x25\x90\x79\x18\xc0\x01\x06\x42\x8e\x48\x50\x27\xf0"
> +    "\x8a\x74\x69\xea\xa1\xf2\x71\xf5\xe5\xd6\xba\xcb\xe6\x3d\xc7\x9c"
> +    "\x11"
> +     "\x02\x81\x81"              /* INTEGER, offset 930, length 129 */
> +    "\x00\xc9\xf5\x04\xad\x34\xe9\x39\xdc\x83\x97\xb6\x3a\x40\xf8\x60"
> +    "\x4b\x69\xec\xf0\x5f\xf3\x88\x69\xcd\xbe\xed\x3c\xc5\x14\x5c\x0c"
> +    "\x54\x2b\xf4\xda\xc6\xc0\x70\x36\xe4\x67\x41\x00\xb7\xc7\x17\x9e"
> +    "\x05\x63\x01\x6d\x77\x06\x71\x24\xcf\x32\x01\xe2\x51\xed\x5e\x90"
> +    "\x38\xed\x4a\xa1\xfb\xb1\x8c\x69\xf4\x08\x96\xef\x0a\x20\x8b\x6c"
> +    "\x77\x85\x33\x92\x9a\xff\x95\xba\x8c\xcd\xa7\x89\xc2\x46\x00\x21"
> +    "\xf3\xd1\xfb\x12\x34\x0c\x99\x8d\x38\xb1\x3b\x66\x5a\x9d\x70\xce"
> +    "\xab\xf3\xe1\xe5\x40\x05\xed\x97\x3d\xd1\x82\x6e\x07\x02\xc0\x8f"
> +    "\x4d"
> +    "\x02\x81\x81"              /* INTEGER, offset 1062, length 129 */
> +    "\x00\xe4\x96\x79\xa8\x6a\x70\xdd\x67\x42\xff\x15\x11\x9e\x01\x71"
> +    "\xac\xf1\x70\x7d\x87\xe2\x6e\x0c\x4d\xbb\x21\x15\xbb\xa7\x4e\x0c"
> +    "\x09\x7e\x82\xca\x91\xbe\xd0\xdd\x9c\x8c\xb0\x77\x64\x30\x1b\x7e"
> +    "\xbb\x69\xcb\x4c\xde\xd6\x6a\xb9\x72\x15\x79\xdc\x05\x99\x69\x8b"
> +    "\x24\xa1\xad\x13\x35\x31\xc0\x0b\xf1\xd2\x06\x7c\x94\x1a\x21\x2f"
> +    "\x02\xb9\xf0\xd0\xbb\xf7\xb7\x78\xf9\x3d\x76\x60\xd6\x6b\x5f\x35"
> +    "\x88\x14\x33\xe6\xbc\xca\x6b\x88\x90\x57\x3b\x0c\xa3\x6e\x47\xdf"
> +    "\x4e\x2f\x4c\xf9\xab\x97\x38\xe4\x20\x32\x32\x96\xc8\x9e\x79\xd3"
> +    "\x12";
> +
> +#define MAX_CHECKER_COUNT 32
> +
> +typedef struct QCryptoAns1DecoderResultChecker QCryptoAns1DecoderResultChecker;
> +struct QCryptoAns1DecoderResultChecker {
> +    int (*action) (const uint8_t **data, size_t *dlen,
> +                   DERDecodeCb cb, void *opaque);
> +    DERDecodeCb cb;
> +    const uint8_t *exp_value;
> +    size_t exp_vlen;
> +};
> +
> +typedef struct QCryptoAns1DecoderTestData QCryptoAns1DecoderTestData;
> +struct QCryptoAns1DecoderTestData {
> +    const char *path;
> +    const uint8_t *test_data;
> +    size_t test_data_len;
> +    QCryptoAns1DecoderResultChecker checker[MAX_CHECKER_COUNT];
> +};
> +
> +typedef struct QCryptoAns1DecoderTestContext QCryptoAns1DecoderTestContext;
> +struct QCryptoAns1DecoderTestContext {
> +    const uint8_t *data;
> +    size_t dlen;
> +};
> +
> +static int checker_callback(void *opaque, const uint8_t *value, size_t vlen)
> +{
> +    QCryptoAns1DecoderResultChecker *checker =
> +        (QCryptoAns1DecoderResultChecker *)opaque;
> +
> +    g_assert(value == checker->exp_value);
> +    g_assert(vlen == checker->exp_vlen);
> +    return 0;
> +}
> +
> +static void test_ans1(const void *opaque)
> +{
> +    const QCryptoAns1DecoderTestData *test_data =
> +        (QCryptoAns1DecoderTestData *)opaque;
> +    QCryptoAns1DecoderTestContext ctx[MAX_CHECKER_COUNT];
> +    int seq_depth = 0, checker_idx = 0;
> +    ctx[seq_depth].data = test_data->test_data;
> +    ctx[seq_depth].dlen = test_data->test_data_len;
> +    bool all_checker_completed = false;
> +
> +    do {
> +        const QCryptoAns1DecoderResultChecker *checker =
> +            &test_data->checker[checker_idx++];
> +        QCryptoAns1DecoderTestContext *c = &ctx[seq_depth];
> +        if (!checker->action) {
> +            all_checker_completed = true;
> +            break;
> +        }
> +        g_assert(checker->action(&c->data, &c->dlen, checker_callback,
> +                                 (void *)checker)
> +            == checker->exp_vlen);
> +        if (checker->action == der_decode_seq) {
> +            ++seq_depth;
> +            ctx[seq_depth].data = checker->exp_value;
> +            ctx[seq_depth].dlen = checker->exp_vlen;
> +        }
> +        while (seq_depth != 0 && ctx[seq_depth].dlen == 0) {
> +            --seq_depth;
> +        }
> +
> +    } while (true);
> +    g_assert(seq_depth == 0);
> +    g_assert(ctx[seq_depth].dlen == 0);
> +    g_assert(all_checker_completed);
> +}
> +
> +static QCryptoAns1DecoderTestData test_data[] = {
> +{
> +    .path = "/crypto/asn1-decoder/parse-rsa512-priv-key",
> +    .test_data = test_rsa512_priv_key,
> +    .test_data_len = sizeof(test_rsa512_priv_key) - 1,
> +    .checker = {
> +        { der_decode_seq, checker_callback,
> +          test_rsa512_priv_key + 4, 313 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 4 + 2, 1 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 7 + 2, 65 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 74 + 2, 3 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 79 + 2, 64 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 145 + 2, 33 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 180 + 2, 33 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 215 + 2, 32 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 249 + 2, 32 },
> +        { der_decode_int, checker_callback,
> +          test_rsa512_priv_key + 283 + 2, 32 },
> +    },
> +},
> +{
> +    .path = "/crypto/asn1-decoder/parse-rsa2048-priv-key",
> +    .test_data = test_rsa2048_priv_key,
> +    .test_data_len = sizeof(test_rsa2048_priv_key) - 1,
> +    .checker = {
> +        { der_decode_seq, checker_callback,
> +          test_rsa2048_priv_key + 4, 1190 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 4 + 2, 1 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 7 + 4, 257 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 268 + 2, 3 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 273 + 4, 257 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 534 + 3, 129 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 666 + 3, 129 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 798 + 3, 129 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 930 + 3, 129 },
> +        { der_decode_int, checker_callback,
> +          test_rsa2048_priv_key + 1062 + 3, 129 },
> +    },
> +},
> +
> +};
> +
> +int main(int argc, char **argv)
> +{
> +    size_t i;
> +    g_test_init(&argc, &argv, NULL);
> +
> +    for (i = 0; i < G_N_ELEMENTS(test_data); i++) {
> +        g_test_add_data_func(test_data[i].path, &test_data[i], test_ans1);
> +    }
> +
> +    return g_test_run();
> +}
> -- 
> 2.20.1
> 

With regards,
Daniel
-- 
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