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/* See LICENSE file for copyright and license details. */
#include "common.h"
/**
* Unmarshal a state from a buffer
*
* @param state Output parameter for the unmarshalled state
* @param buf The buffer from which the state shall be unmarshalled
* @param bufsize The maximum number of bytes that can be unmarshalled
* @return The number of read bytes, 0 on failure
*/
size_t
libsha2_unmarshal(struct libsha2_state *restrict state, const char *restrict buf, size_t bufsize)
{
size_t off = 0;
if (bufsize < sizeof(int) + sizeof(enum libsha2_algorithm) + sizeof(size_t)) {
errno = EINVAL;
return 0;
}
if (*(const int *)buf) { /* version */
errno = EINVAL;
return 0;
}
off += sizeof(int);
state->algorithm = *(const enum libsha2_algorithm *)&buf[off];
off += sizeof(enum libsha2_algorithm);
state->message_size = *(const size_t *)&buf[off];
off += sizeof(size_t);
switch (state->algorithm) {
case LIBSHA2_224:
case LIBSHA2_256:
if (bufsize - off < sizeof(state->k.b32) + sizeof(state->w.b32) + sizeof(state->h.b32)) {
errno = EINVAL;
return 0;
}
memcpy(state->k.b32, &buf[off], sizeof(state->k.b32));
off += sizeof(state->k.b32);
memcpy(state->w.b32, &buf[off], sizeof(state->w.b32));
off += sizeof(state->w.b32);
memcpy(state->h.b32, &buf[off], sizeof(state->h.b32));
off += sizeof(state->h.b32);
break;
case LIBSHA2_384:
case LIBSHA2_512:
case LIBSHA2_512_224:
case LIBSHA2_512_256:
if (bufsize - off < sizeof(state->k.b64) + sizeof(state->w.b64) + sizeof(state->h.b64)) {
errno = EINVAL;
return 0;
}
memcpy(state->k.b64, &buf[off], sizeof(state->k.b64));
off += sizeof(state->k.b64);
memcpy(state->w.b64, &buf[off], sizeof(state->w.b64));
off += sizeof(state->w.b64);
memcpy(state->h.b64, &buf[off], sizeof(state->h.b64));
off += sizeof(state->h.b64);
break;
default:
errno = EINVAL;
return 0;
}
if (bufsize - off < sizeof(size_t)) {
errno = EINVAL;
return 0;
}
state->chunk_size = *(const size_t *)&buf[off];
off += sizeof(size_t);
if (bufsize - off < state->message_size % state->chunk_size) {
errno = EINVAL;
return 0;
}
memcpy(state->chunk, &buf[off], state->message_size % state->chunk_size);
off += state->message_size % state->chunk_size;
return off;
}
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