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-rw-r--r--unmarshal.c80
1 files changed, 80 insertions, 0 deletions
diff --git a/unmarshal.c b/unmarshal.c
new file mode 100644
index 0000000..2a47b92
--- /dev/null
+++ b/unmarshal.c
@@ -0,0 +1,80 @@
+/* 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 (*(int *)buf) { /* version */
+ errno = EINVAL;
+ return 0;
+ }
+ off += sizeof(int);
+
+ state->algorithm = *(enum libsha2_algorithm *)&buf[off];
+ off += sizeof(enum libsha2_algorithm);
+ state->message_size = *(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(state->chunk) + sizeof(size_t)) {
+ errno = EINVAL;
+ return 0;
+ }
+ memcpy(state->chunk, &buf[off], sizeof(state->chunk));
+ off += sizeof(state->chunk);
+ state->chunk_size = *(size_t *)&buf[off];
+ off += sizeof(size_t);
+
+ return off;
+}