1 files changed, 84 insertions, 0 deletions
diff --git a/libsecauth_parse_spec.c b/libsecauth_parse_spec.c
new file mode 100644
index 0000000..2961268
--- /dev/null
+++ b/libsecauth_parse_spec.c
@@ -0,0 +1,84 @@
+/* See LICENSE file for copyright and license details. */
+#include "libsecauth.h"
+
+#include <ctype.h>
+#include <errno.h>
+#include <string.h>
+
+
+static char *
+get_subhash(char *s, char **endp)
+{
+	size_t depth = 0;
+	char *ret;
+
+	if (s[0] == '{' && s[1] == '$') {
+		s = ret = &s[2];
+	} else {
+		ret = s;
+	}
+	for (; s[0]; s++) {
+		if (s[0] == '{' && s[1] == '$' && s[-1] == '$') {
+			depth += 1;
+		} else if (s[0] == '}' && s[1] == '$' && s[-1] == '$') {
+			if (!depth)
+				return NULL;
+			if (!--depth) {
+				*s++ = '\0';
+				*s++ = '\0';
+				return ret;
+			}
+		} else if (s[0] == '$' && !depth) {
+			*s++ = '\0';
+			return ret;
+		}
+	}
+
+	return NULL;
+}
+
+static int
+strtou32(const char *s, uint32_t *valp)
+{
+	for (*valp = 0; isdigit(*s); s++) {
+		if (*valp > (UINT32_MAX - (uint32_t)(*s & 15)) / 10)
+			return -1;
+		*valp = *valp * 10 + (uint32_t)(*s & 15);
+	}
+	return *s ? -1 : 0;
+}
+
+int
+libsecauth_parse_spec(struct libsecauth_spec *spec, char *s)
+{
+	const char *client_rounds, *server_rounds;
+	size_t slen = strlen(s);
+
+	memset(spec, 0, sizeof(*spec));
+
+	if (strncmp(s, "$secauth$", sizeof("$secauth$") - 1))
+		goto invalid;
+	s = &s[sizeof("$secauth$") - 1];
+
+	spec->prehash  = get_subhash(s, &s);
+	spec->xferhash = get_subhash(s, &s);
+	client_rounds  = get_subhash(s, &s);
+	server_rounds  = get_subhash(s, &s);
+	spec->posthash = get_subhash(s, &s);
+	spec->expected = get_subhash(s, &s);
+
+	if (client_rounds && strtou32(client_rounds, &spec->client_rounds))
+		goto invalid;
+	if (server_rounds && strtou32(server_rounds, &spec->server_rounds))
+		goto invalid;
+
+	if (*s)
+		goto invalid;
+
+	return 0;
+
+invalid:
+	memset(s, 0, slen);
+	errno = EINVAL;
+	return -1;
+}