83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
/****************************************************************************
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* net/utils/net_getrandom.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <string.h>
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#include <sys/param.h>
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#include <sys/random.h>
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#include <nuttx/clock.h>
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#include <nuttx/hashtable.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: net_getrandom
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*
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* Description:
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* Fill a buffer of arbitrary length with randomness. This function is
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* guaranteed to be success.
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*
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* Input Parameters:
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* bytes - Buffer for returned random bytes
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* nbytes - Number of bytes requested.
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*
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****************************************************************************/
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void net_getrandom(FAR void *bytes, size_t nbytes)
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{
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#if defined(CONFIG_DEV_URANDOM) || defined(CONFIG_DEV_RANDOM)
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ssize_t ret = getrandom(bytes, nbytes, 0);
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if (ret < 0)
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{
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ret = getrandom(bytes, nbytes, GRND_RANDOM);
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}
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if (ret == nbytes)
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{
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return;
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}
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#endif
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/* Fallback to hash of clock_systime_ticks(), minus nbytes to avoid getting
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* same tick count when looping more than once.
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*/
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while (nbytes > 0)
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{
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uint32_t hash = HASH(clock_systime_ticks() - nbytes, 32);
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size_t ncopy = MIN(nbytes, sizeof(hash));
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memcpy(bytes, &hash, ncopy);
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nbytes -= ncopy;
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bytes = (FAR uint8_t *)bytes + ncopy;
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}
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}
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