Nest: Allow specifying security keys as hex bytes as well as strings

Add support for specifying a password in hexadecimal format, The result
is the same whether a password is specified as a quoted string or a
hex-encoded byte string, this just makes it more convenient to input
high-entropy byte strings as MAC keys.

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/strtoul.c b/lib/strtoul.c
index 44a1bb1d..a5b11f68 100644
--- a/lib/strtoul.c
+++ b/lib/strtoul.c
@@ -59,3 +59,30 @@ bstrtoul16(const char *str, char **end)
   errno = ERANGE;
   return UINT64_MAX;
 }
+
+byte
+bstrtobyte16(const char *str)
+{
+  byte out = 0;
+  for (int i=0; i<2; i++) {
+    switch (str[i]) {
+      case '0' ... '9':
+	out *= 16;
+	out += str[i] - '0';
+	break;
+      case 'a' ... 'f':
+	out *= 16;
+	out += str[i] + 10 - 'a';
+	break;
+      case 'A' ... 'F':
+	out *= 16;
+	out += str[i] + 10 - 'A';
+	break;
+      default:
+	errno = ERANGE;
+	return -1;
+    }
+  }
+
+  return out;
+}