Consolidate function for testing for ASN.1 string types

2 files changed, 21 insertions, 8 deletions

diff --git a/src/lib/asn1/asn1_str.cpp b/src/lib/asn1/asn1_str.cpp
index d90aa215b..8b9524de2 100644
--- a/src/lib/asn1/asn1_str.cpp
+++ b/src/lib/asn1/asn1_str.cpp
@@ -55,14 +55,7 @@ ASN1_Tag choose_encoding(const std::string& str)
 
 void assert_is_string_type(ASN1_Tag tag)
    {
-   if(tag != NUMERIC_STRING &&
-      tag != PRINTABLE_STRING &&
-      tag != VISIBLE_STRING &&
-      tag != T61_STRING &&
-      tag != IA5_STRING &&
-      tag != UTF8_STRING &&
-      tag != BMP_STRING &&
-      tag != UNIVERSAL_STRING)
+   if(!ASN1_String::is_string_type(tag))
       {
       throw Invalid_Argument("ASN1_String: Unknown string type " +
                              std::to_string(tag));
@@ -71,6 +64,20 @@ void assert_is_string_type(ASN1_Tag tag)
 
 }
 
+//static
+bool ASN1_String::is_string_type(ASN1_Tag tag)
+   {
+   return (tag == NUMERIC_STRING ||
+           tag == PRINTABLE_STRING ||
+           tag == VISIBLE_STRING ||
+           tag == T61_STRING ||
+           tag == IA5_STRING ||
+           tag == UTF8_STRING ||
+           tag == BMP_STRING ||
+           tag == UNIVERSAL_STRING);
+   }
+
+
 /*
 * Create an ASN1_String
 */
diff --git a/src/lib/asn1/asn1_str.h b/src/lib/asn1/asn1_str.h
index f19265494..77e2fc145 100644
--- a/src/lib/asn1/asn1_str.h
+++ b/src/lib/asn1/asn1_str.h
@@ -29,6 +29,12 @@ class BOTAN_PUBLIC_API(2,0) ASN1_String final : public ASN1_Object
       std::string BOTAN_DEPRECATED("Use value() to get UTF-8 string instead")
          iso_8859() const;
 
+      /**
+      * Return true iff this is a tag for a known string type we can handle.
+      * This ignores string types that are not supported, eg teletexString
+      */
+      static bool is_string_type(ASN1_Tag tag);
+
       explicit ASN1_String(const std::string& utf8 = "");
       ASN1_String(const std::string& utf8, ASN1_Tag tag);
    private: