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/*-
* Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
* Redistribution and modifications are permitted subject to BSD license.
*/
#include <asn_internal.h>
#include <errno.h>
static ssize_t der_write_TL(ber_tlv_tag_t tag, ber_tlv_len_t len,
asn_app_consume_bytes_f *cb, void *app_key, int constructed);
/*
* The DER encoder of any type.
*/
asn_enc_rval_t
der_encode(asn_TYPE_descriptor_t *type_descriptor, void *struct_ptr,
asn_app_consume_bytes_f *consume_bytes, void *app_key) {
ASN_DEBUG("DER encoder invoked for %s",
type_descriptor->name);
/*
* Invoke type-specific encoder.
*/
return type_descriptor->der_encoder(type_descriptor,
struct_ptr, /* Pointer to the destination structure */
0, 0,
consume_bytes, app_key);
}
/*
* Argument type and callback necessary for der_encode_to_buffer().
*/
typedef struct enc_to_buf_arg {
void *buffer;
size_t left;
} enc_to_buf_arg;
static int encode_to_buffer_cb(const void *buffer, size_t size, void *key) {
enc_to_buf_arg *arg = (enc_to_buf_arg *)key;
if(arg->left < size)
return -1; /* Data exceeds the available buffer size */
memcpy(arg->buffer, buffer, size);
arg->buffer = ((char *)arg->buffer) + size;
arg->left -= size;
return 0;
}
/*
* A variant of the der_encode() which encodes the data into the provided buffer
*/
asn_enc_rval_t
der_encode_to_buffer(asn_TYPE_descriptor_t *type_descriptor, void *struct_ptr,
void *buffer, size_t buffer_size) {
enc_to_buf_arg arg;
asn_enc_rval_t ec;
arg.buffer = buffer;
arg.left = buffer_size;
ec = type_descriptor->der_encoder(type_descriptor,
struct_ptr, /* Pointer to the destination structure */
0, 0, encode_to_buffer_cb, &arg);
if(ec.encoded != -1) {
assert(ec.encoded == (ssize_t)(buffer_size - arg.left));
/* Return the encoded contents size */
}
return ec;
}
/*
* Write out leading TL[v] sequence according to the type definition.
*/
ssize_t
der_write_tags(asn_TYPE_descriptor_t *sd,
size_t struct_length,
int tag_mode, int last_tag_form,
ber_tlv_tag_t tag, /* EXPLICIT or IMPLICIT tag */
asn_app_consume_bytes_f *cb,
void *app_key) {
ber_tlv_tag_t *tags; /* Copy of tags stream */
int tags_count; /* Number of tags */
size_t overall_length;
ssize_t *lens;
int i;
ASN_DEBUG("Writing tags (%s, tm=%d, tc=%d, tag=%s, mtc=%d)",
sd->name, tag_mode, sd->tags_count,
ber_tlv_tag_string(tag),
tag_mode
?(sd->tags_count+1
-((tag_mode == -1) && sd->tags_count))
:sd->tags_count
);
if(tag_mode) {
/*
* Instead of doing shaman dance like we do in ber_check_tags(),
* allocate a small array on the stack
* and initialize it appropriately.
*/
int stag_offset;
tags = (ber_tlv_tag_t *)alloca((sd->tags_count + 1) * sizeof(ber_tlv_tag_t));
if(!tags) { /* Can fail on !x86 */
errno = ENOMEM;
return -1;
}
tags_count = sd->tags_count
+ 1 /* EXPLICIT or IMPLICIT tag is given */
- ((tag_mode == -1) && sd->tags_count);
/* Copy tags over */
tags[0] = tag;
stag_offset = -1 + ((tag_mode == -1) && sd->tags_count);
for(i = 1; i < tags_count; i++)
tags[i] = sd->tags[i + stag_offset];
} else {
tags = sd->tags;
tags_count = sd->tags_count;
}
/* No tags to write */
if(tags_count == 0)
return 0;
lens = (ssize_t *)alloca(tags_count * sizeof(lens[0]));
if(!lens) {
errno = ENOMEM;
return -1;
}
/*
* Array of tags is initialized.
* Now, compute the size of the TLV pairs, from right to left.
*/
overall_length = struct_length;
for(i = tags_count - 1; i >= 0; --i) {
lens[i] = der_write_TL(tags[i], overall_length, 0, 0, 0);
if(lens[i] == -1) return -1;
overall_length += lens[i];
lens[i] = overall_length - lens[i];
}
if(!cb) return overall_length - struct_length;
ASN_DEBUG("%s %s TL sequence (%d elements)",
cb?"Encoding":"Estimating", sd->name, tags_count);
/*
* Encode the TL sequence for real.
*/
for(i = 0; i < tags_count; i++) {
ssize_t len;
int _constr;
/* Check if this tag happens to be constructed */
_constr = (last_tag_form || i < (tags_count - 1));
len = der_write_TL(tags[i], lens[i], cb, app_key, _constr);
if(len == -1) return -1;
}
return overall_length - struct_length;
}
static ssize_t
der_write_TL(ber_tlv_tag_t tag, ber_tlv_len_t len,
asn_app_consume_bytes_f *cb, void *app_key,
int constructed) {
uint8_t buf[32];
size_t size = 0;
int buf_size = cb?sizeof(buf):0;
ssize_t tmp;
/* Serialize tag (T from TLV) into possibly zero-length buffer */
tmp = ber_tlv_tag_serialize(tag, buf, buf_size);
if(tmp == -1 || tmp > (ssize_t)sizeof(buf)) return -1;
size += tmp;
/* Serialize length (L from TLV) into possibly zero-length buffer */
tmp = der_tlv_length_serialize(len, buf+size, buf_size?buf_size-size:0);
if(tmp == -1) return -1;
size += tmp;
if(size > sizeof(buf))
return -1;
/*
* If callback is specified, invoke it, and check its return value.
*/
if(cb) {
if(constructed) *buf |= 0x20;
if(cb(buf, size, app_key) < 0)
return -1;
}
return size;
}
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