[settings] Add md5 encoding type for doing ${foo:md5}

This obviously only works for formatting, not parsing.
This makes it possible to implement client side password
checks without giving the password away too easily.
Not super secure as it's md5, but enough for basic protection.

1 files changed, 47 insertions, 0 deletions

diff --git a/src/core/settings.c b/src/core/settings.c
index 3e5d416e..df4fe9fc 100644
--- a/src/core/settings.c
+++ b/src/core/settings.c
@@ -45,6 +45,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/init.h>
 #include <ipxe/version.h>
 #include <ipxe/settings.h>
+#include <ipxe/md5.h>
 
 /** @file
  *
@@ -2132,6 +2133,46 @@ static int format_hex_raw_setting ( const struct setting_type *type __unused,
 	return hex_encode ( 0, raw, raw_len, buf, len );
 }
 
+/**
+ * Parsing md5 setting doesn't make any sense
+ *
+ * @v type		Setting type
+ * @v value		Formatted setting value
+ * @v buf		Buffer to contain raw value
+ * @v len		Length of buffer
+ * @v size		Integer size, in bytes
+ * @ret len		Length of raw value, or negative error
+ */
+static int parse_md5_setting ( const struct setting_type *type __unused,
+				   const char *value __unused, void *buf __unused,
+				   size_t len __unused ) {
+	return -ENOTSUP;
+}
+
+/**
+ * Format setting value as md5 hash (hex representation)
+ *
+ * @v type		Setting type
+ * @v raw		Raw setting value
+ * @v raw_len		Length of raw setting value
+ * @v buf		Buffer to contain formatted value
+ * @v len		Length of buffer
+ * @ret len		Length of formatted value, or negative error
+ */
+static int format_md5_setting ( const struct setting_type *type __unused,
+				    const void *raw, size_t raw_len,
+				    char *buf, size_t len ) {
+	struct md5_context ctx;
+	uint8_t digest[MD5_DIGEST_SIZE];
+
+	if ( len < MD5_DIGEST_SIZE )
+		return -ENOSPC;
+	digest_init ( &md5_algorithm, &ctx );
+	digest_update ( &md5_algorithm, &ctx, raw, raw_len );
+	digest_final ( &md5_algorithm, &ctx, digest );
+	return hex_encode ( 0, digest, sizeof(digest), buf, len );
+}
+
 /** A hex-string setting (colon-delimited) */
 const struct setting_type setting_type_hex __setting_type = {
 	.name = "hex",
@@ -2153,6 +2194,12 @@ const struct setting_type setting_type_hexraw __setting_type = {
 	.format = format_hex_raw_setting,
 };
 
+const struct setting_type setting_type_md5 __setting_type = {
+	.name = "md5",
+	.parse = parse_md5_setting,
+	.format = format_md5_setting,
+};
+
 /**
  * Parse Base64-encoded setting value
  *