First commit

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 59 insertions, 0 deletions

diff --git a/unmarshal.c b/unmarshal.c
new file mode 100644
index 0000000..e89a8dd
--- /dev/null
+++ b/unmarshal.c
@@ -0,0 +1,59 @@
+/* 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
+libsha1_unmarshal(struct libsha1_state *restrict state, const void *restrict buf_, size_t bufsize)
+{
+	const char *restrict buf = buf_;
+	size_t off = 0;
+
+	if (bufsize < sizeof(int) + sizeof(enum libsha1_algorithm) + sizeof(size_t)) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	if (*(const int *)buf) { /* version */
+		errno = EINVAL;
+		return 0;
+	}
+	off += sizeof(int);
+
+	state->algorithm = *(const enum libsha1_algorithm *)&buf[off];
+	off += sizeof(enum libsha1_algorithm);
+	state->message_size = *(const size_t *)&buf[off];
+	off += sizeof(size_t);
+
+	if (bufsize - off < sizeof(state->w) + sizeof(state->h)) {
+		errno = EINVAL;
+		return 0;
+	}
+	memcpy(state->w, &buf[off], sizeof(state->w));
+	off += sizeof(state->w);
+	memcpy(state->h, &buf[off], sizeof(state->h));
+	off += sizeof(state->h);
+
+	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 / 8) % state->chunk_size) {
+		errno = EINVAL;
+		return 0;
+	}
+	memcpy(state->chunk, &buf[off], (state->message_size / 8) % state->chunk_size);
+	off += (state->message_size / 8) % state->chunk_size;
+
+	return off;
+}