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/**
* @file der_encoder.c
*
* @brief Implementation of der_encoder_t.
*/
/*
* Copyright (C) 2005 Jan Hutter, Martin Willi
* Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program 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 General Public License
* for more details.
*/
#include <gmp.h>
#include "der_encoder.h"
#include <utils/allocator.h>
#include <daemon.h>
typedef struct private_der_encoder_t private_der_encoder_t;
/**
* Private data of a der_encoder_t object.
*/
struct private_der_encoder_t {
/**
* Public interface for this signer.
*/
der_encoder_t public;
asn1_rule_t *rule;
asn1_rule_t *first_rule;
void *output;
logger_t *logger;
};
static status_t read_hdr(private_der_encoder_t *this, chunk_t *data);
static status_t read_sequence(private_der_encoder_t *this, chunk_t data)
{
while (this->rule->type != ASN1_END)
{
read_hdr(this, &data);
}
return SUCCESS;
}
static status_t read_int(private_der_encoder_t *this, chunk_t data)
{
this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_INTEGER", data);
u_int *integ = (u_int*)((u_int8_t*)this->output + this->rule->data_offset);
*integ = 0;
while (data.len-- > 0)
{
*integ = 256 * (*integ) + *data.ptr++;
}
return SUCCESS;
}
static status_t read_mpz(private_der_encoder_t *this, chunk_t data)
{
this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "ASN1_INTEGER as mpz", data);
mpz_t *mpz = (mpz_t*)((u_int8_t*)this->output + this->rule->data_offset);
mpz_import(*mpz, data.len, 1, 1, 1, 0, data.ptr);
return SUCCESS;
}
static u_int32_t read_length(chunk_t *data)
{
u_int8_t n;
size_t len;
/* read first octet of length field */
n = *data->ptr++;
if ((n & 0x80) == 0)
{
/* single length octet */
return n;
}
/* composite length, determine number of length octets */
n &= 0x7f;
if (n > data->len)
{
/* length longer than available bytes */
return -1;
}
if (n > sizeof(len))
{
/* larger than size_t can hold */
return -1;
}
len = 0;
while (n-- > 0)
{
len = 256 * len + *data->ptr++;
}
return len;
}
static status_t read_hdr(private_der_encoder_t *this, chunk_t *data)
{
chunk_t inner;
/* advance to the next rule */
this->rule++;
if (this->rule->type == ASN1_END)
{
return SUCCESS;
}
this->logger->log(this->logger, CONTROL|LEVEL2, "reading header of rule %s",
mapping_find(asn1_type_m, this->rule->type));
this->logger->log_chunk(this->logger, CONTROL|LEVEL2, "reading from:", *data);
/* read type, advance in data */
if (*(data->ptr) != this->rule->type)
{
this->logger->log(this->logger, CONTROL|LEVEL2, "Bad byte found (%x)", *data->ptr);
return PARSE_ERROR;
}
data->ptr++;
data->len--;
/* read length, advance in data */
inner.len = read_length(data);
if (inner.len == -1)
{
this->logger->log(this->logger, CONTROL|LEVEL2, "Error reading length");
return PARSE_ERROR;
}
this->logger->log(this->logger, CONTROL|LEVEL2, "Length is %d",
inner.len);
inner.ptr = data->ptr;
/* advance in data */
data->ptr += inner.len;
data->len -= inner.len;
/* process inner */
switch (this->rule->type)
{
case ASN1_INTEGER:
if (this->rule->flags & ASN1_MPZ)
{
read_mpz(this, inner);
}
else
{
read_int(this, inner);
}
break;
case ASN1_SEQUENCE:
read_sequence(this, inner);
break;
default:
break;
}
return SUCCESS;
}
static status_t decode(private_der_encoder_t *this, chunk_t input, void *output)
{
this->rule = this->first_rule - 1;
this->output = output;
return read_hdr(this, &input);
}
/**
* Implementation of der_encoder.destroy.
*/
static void destroy(private_der_encoder_t *this)
{
allocator_free(this);
}
/*
* Described in header.
*/
der_encoder_t *der_encoder_create(asn1_rule_t *rules)
{
private_der_encoder_t *this = allocator_alloc_thing(private_der_encoder_t);
/* public functions */
this->public.decode = (status_t (*) (der_encoder_t*,chunk_t,void*))decode;
this->public.destroy = (void (*) (der_encoder_t*))destroy;
this->first_rule = rules;
this->logger = charon->logger_manager->get_logger(charon->logger_manager, DER_DECODER);
return &(this->public);
}
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