implemented generic string write function to match correct string tag

thomas-dee · Nov 2, 2017 · cf43076 · cf43076
1 parent fea07a3
commit cf43076
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Showing 3 changed files with 29 additions and 50 deletions.
diff --git a/include/mbedtls/asn1write.h b/include/mbedtls/asn1write.h
@@ -151,6 +151,21 @@ int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolea
  */
 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val );
 
+/**
+ * \brief           Write a given string tag and
+ *                  value in ASN.1 format
+ *                  Note: function works backwards in data buffer
+ *
+ * \param p         reference to current position pointer
+ * \param start     start of the buffer (for bounds-checking)
+ * \param tag       the tag to write
+ * \param text      the text to write
+ * \param text_len  length of the text
+ *
+ * \return          the length written or a negative error code
+ */
+int mbedtls_asn1_write_any_string( unsigned char **p, unsigned char *start,
+                                 int tag, const char *text, size_t text_len );
 /**
  * \brief           Write a printable string tag (MBEDTLS_ASN1_PRINTABLE_STRING) and
  *                  value in ASN.1 format

diff --git a/library/asn1write.c b/library/asn1write.c
@@ -257,7 +257,7 @@ int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
     return( (int) len );
 }
 
-int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start,
+int mbedtls_asn1_write_any_string( unsigned char **p, unsigned char *start, int tag,
     const char *text, size_t text_len )
 {
     int ret;
@@ -267,39 +267,27 @@ int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start,
         (const unsigned char *) text, text_len ) );
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_UTF8_STRING ) );
+    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) );
 
     return( (int) len );
 }
 
+int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start,
+    const char *text, size_t text_len )
+{
+    return( mbedtls_asn1_write_any_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len) );
+}
+
 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
                                  const char *text, size_t text_len )
 {
-    int ret;
-    size_t len = 0;
-
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
-                  (const unsigned char *) text, text_len ) );
-
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_PRINTABLE_STRING ) );
-
-    return( (int) len );
+    return( mbedtls_asn1_write_any_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, text_len) );
 }
 
 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
                            const char *text, size_t text_len )
 {
-    int ret;
-    size_t len = 0;
-
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
-                  (const unsigned char *) text, text_len ) );
-
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );
-
-    return( (int) len );
+    return( mbedtls_asn1_write_any_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len) );
 }
 
 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,

diff --git a/library/x509_create.c b/library/x509_create.c
@@ -210,34 +210,10 @@ static int x509_write_name( unsigned char **p, unsigned char *start, mbedtls_asn
     const unsigned char *name   = cur_name->val.p;
     size_t name_len             = cur_name->val.len;
 
-    // Write PrintableString for all except MBEDTLS_OID_PKCS9_EMAIL
-    //
-    if( MBEDTLS_OID_SIZE( MBEDTLS_OID_PKCS9_EMAIL ) == oid_len &&
-        memcmp( oid, MBEDTLS_OID_PKCS9_EMAIL, oid_len ) == 0 )
-    {
-        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_ia5_string( p, start,
-                                                  (const char *) name,
-                                                  name_len ) );
-    }
-    else if (cur_name->val.tag == MBEDTLS_ASN1_UTF8_STRING)
-    {
-        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_utf8_string( p, start,
-            (const char *) name,
-            name_len ) );
-    }
-    else if (cur_name->val.tag == MBEDTLS_ASN1_IA5_STRING)
-    {
-        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_ia5_string( p, start,
-                                                  (const char *) name,
-                                                  name_len ) );
-    }
-    else
-    {
-        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_printable_string( p, start,
-                                                        (const char *) name,
-                                                        name_len ) );
-    }
-
+    // Write correct string tag and value
+    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_any_string( p, start, cur_name->val.tag,
+                                                                (const char *) name,
+                                                                name_len ) );
     // Write OID
     //
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );