buffer.c

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/*****************************************************************************
 *   (c) 2020 Ledger SAS.
 *
 *  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 <stdint.h>   // uint*_t
#include <stddef.h>   // size_t
#include <stdbool.h>  // bool
#include <string.h>   // memmove
 
#include "buffer.h"
#include "read.h"
#include "varint.h"
#include "bip32.h"
 
bool buffer_can_read(const buffer_t *buffer, size_t n)
{
    return buffer->size - buffer->offset >= n;
}
 
bool buffer_seek_set(buffer_t *buffer, size_t offset)
{
    if (offset > buffer->size) {
        return false;
    }
 
    buffer->offset = offset;
 
    return true;
}
 
bool buffer_seek_cur(buffer_t *buffer, size_t offset)
{
    if (buffer->offset + offset < buffer->offset ||  // overflow
        buffer->offset + offset > buffer->size) {    // exceed buffer size
        return false;
    }
 
    buffer->offset += offset;
 
    return true;
}
 
bool buffer_seek_end(buffer_t *buffer, size_t offset)
{
    if (offset > buffer->size) {
        return false;
    }
 
    buffer->offset = buffer->size - offset;
 
    return true;
}
 
bool buffer_read_u8(buffer_t *buffer, uint8_t *value)
{
    if (!buffer_can_read(buffer, 1)) {
        *value = 0;
 
        return false;
    }
 
    *value = buffer->ptr[buffer->offset];
    buffer_seek_cur(buffer, 1);
 
    return true;
}
 
bool buffer_read_u16(buffer_t *buffer, uint16_t *value, endianness_t endianness)
{
    if (!buffer_can_read(buffer, 2)) {
        *value = 0;
 
        return false;
    }
 
    *value = ((endianness == BE) ? read_u16_be(buffer->ptr, buffer->offset)
                                 : read_u16_le(buffer->ptr, buffer->offset));
 
    buffer_seek_cur(buffer, 2);
 
    return true;
}
 
bool buffer_read_u32(buffer_t *buffer, uint32_t *value, endianness_t endianness)
{
    if (!buffer_can_read(buffer, 4)) {
        *value = 0;
 
        return false;
    }
 
    *value = ((endianness == BE) ? read_u32_be(buffer->ptr, buffer->offset)
                                 : read_u32_le(buffer->ptr, buffer->offset));
 
    buffer_seek_cur(buffer, 4);
 
    return true;
}
 
bool buffer_read_u64(buffer_t *buffer, uint64_t *value, endianness_t endianness)
{
    if (!buffer_can_read(buffer, 8)) {
        *value = 0;
 
        return false;
    }
 
    *value = ((endianness == BE) ? read_u64_be(buffer->ptr, buffer->offset)
                                 : read_u64_le(buffer->ptr, buffer->offset));
 
    buffer_seek_cur(buffer, 8);
 
    return true;
}
 
bool buffer_read_varint(buffer_t *buffer, uint64_t *value)
{
    int length = varint_read(buffer->ptr + buffer->offset, buffer->size - buffer->offset, value);
 
    if (length < 0) {
        *value = 0;
 
        return false;
    }
 
    return buffer_seek_cur(buffer, (size_t) length);
}
 
bool buffer_read_bip32_path(buffer_t *buffer, uint32_t *out, size_t out_len)
{
    if (!bip32_path_read(
            buffer->ptr + buffer->offset, buffer->size - buffer->offset, out, out_len)) {
        return false;
    }
 
    buffer_seek_cur(buffer, sizeof(*out) * out_len);
 
    return true;
}
 
bool buffer_copy(const buffer_t *buffer, uint8_t *out, size_t out_len)
{
    if (buffer->size - buffer->offset > out_len) {
        return false;
    }
 
    memmove(out, buffer->ptr + buffer->offset, buffer->size - buffer->offset);
 
    return true;
}
 
bool buffer_move(buffer_t *buffer, uint8_t *out, size_t out_len)
{
    if (!buffer_copy(buffer, out, out_len)) {
        return false;
    }
 
    buffer_seek_cur(buffer, out_len);
 
    return true;
}