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.

2 files changed, 28 insertions, 0 deletions

diff --git a/lib/string.h b/lib/string.h
index 0f650178..976b1c24 100644
--- a/lib/string.h
+++ b/lib/string.h
@@ -26,6 +26,7 @@ void buffer_puts(buffer *buf, const char *str);
 
 u64 bstrtoul10(const char *str, char **end);
 u64 bstrtoul16(const char *str, char **end);
+byte bstrtobyte16(const char *str);
 
 int patmatch(const byte *pat, const byte *str);
 
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;
+}