Introduce a helper macro to check for ASN.1 string tags
This commit introduces a macro `MBEDTLS_ASN1_IS_STRING_TAG`
that can be used to check if an ASN.1 tag is among the list
of string tags:
- MBEDTLS_ASN1_BMP_STRING
- MBEDTLS_ASN1_UTF8_STRING
- MBEDTLS_ASN1_T61_STRING
- MBEDTLS_ASN1_IA5_STRING
- MBEDTLS_ASN1_UNIVERSAL_STRING
- MBEDTLS_ASN1_PRINTABLE_STRING
- MBEDTLS_ASN1_BIT_STRING
diff --git a/include/mbedtls/asn1.h b/include/mbedtls/asn1.h
index 96c1c9a..2fb6de0 100644
--- a/include/mbedtls/asn1.h
+++ b/include/mbedtls/asn1.h
@@ -89,6 +89,18 @@
#define MBEDTLS_ASN1_CONSTRUCTED 0x20
#define MBEDTLS_ASN1_CONTEXT_SPECIFIC 0x80
+/* Slightly smaller way to check if tag is a string tag
+ * compared to canonical implementation. */
+#define MBEDTLS_ASN1_IS_STRING_TAG( tag ) \
+ ( ( tag ) < 32u && ( \
+ ( ( 1u << ( tag ) ) & ( ( 1u << MBEDTLS_ASN1_BMP_STRING ) | \
+ ( 1u << MBEDTLS_ASN1_UTF8_STRING ) | \
+ ( 1u << MBEDTLS_ASN1_T61_STRING ) | \
+ ( 1u << MBEDTLS_ASN1_IA5_STRING ) | \
+ ( 1u << MBEDTLS_ASN1_UNIVERSAL_STRING ) | \
+ ( 1u << MBEDTLS_ASN1_PRINTABLE_STRING ) | \
+ ( 1u << MBEDTLS_ASN1_BIT_STRING ) ) ) != 0 ) )
+
/*
* Bit masks for each of the components of an ASN.1 tag as specified in
* ITU X.690 (08/2015), section 8.1 "General rules for encoding",
diff --git a/library/x509.c b/library/x509.c
index 2e7bd57..9d9db23 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -375,12 +375,11 @@
return( MBEDTLS_ERR_X509_INVALID_NAME +
MBEDTLS_ERR_ASN1_OUT_OF_DATA );
- if( **p != MBEDTLS_ASN1_BMP_STRING && **p != MBEDTLS_ASN1_UTF8_STRING &&
- **p != MBEDTLS_ASN1_T61_STRING && **p != MBEDTLS_ASN1_PRINTABLE_STRING &&
- **p != MBEDTLS_ASN1_IA5_STRING && **p != MBEDTLS_ASN1_UNIVERSAL_STRING &&
- **p != MBEDTLS_ASN1_BIT_STRING )
+ if( !MBEDTLS_ASN1_IS_STRING_TAG( **p ) )
+ {
return( MBEDTLS_ERR_X509_INVALID_NAME +
MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+ }
val = &cur->val;
val->tag = *(*p)++;