Add explanatory comments to raw DER test data

Break down the DER-encoded ASN.1 test data into its structure in a
comment and explain it, to make it easier to understand where the data
came from and how it is corrupted.

Signed-off-by: David Horstmann <david.horstmann@arm.com>

tests/suites/test_suite_x509parse.data

@@ -427,9 +427,43 @@ X509 Get Modified DN #5 Name exactly 255 bytes, ending with comma requiring esca
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
 mbedtls_x509_dn_gets_subject_replace:"data_files/server1.crt":"12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234,":"":MBEDTLS_ERR_X509_BUFFER_TOO_SMALL
 
+# Parse the following valid DN:
+#
+# 31 0B <- Set of
+#     30 09 <- Sequence of
+#         06 03 55 04 06 <- OID 2.5.4.6 countryName (C)
+#         13 02 4E 4C <- PrintableString "NL"
+# 31 11 <- Set of
+#     30 0F <- Sequence of
+#         06 03 55 04 0A <- OID 2.5.4.10 organizationName (O)
+#         0C 08 50 6F 6C 61 72 53 53 4C <- UTF8String "PolarSSL"
+# 31 19 <- Set of
+#     30 17 <- Sequence of
+#         06 03 55 04 03 <- OID 2.5.4.3 commonName (CN)
+#         0C 10 50 6F 6C 61 72 53 53 4C 20 54 65 73 74 20 43 41 <- UTF8String "PolarSSL Test CA"
+#
 X509 Get Name Valid DN
 mbedtls_x509_get_name:"310B3009060355040613024E4C3111300F060355040A0C08506F6C617253534C3119301706035504030C10506F6C617253534C2054657374204341":0
 
+# Parse the following corrupted DN:
+#
+# 31 0B <- Set of
+#     30 09 <- Sequence of
+#         06 03 55 04 06 <- OID 2.5.4.6 countryName (C)
+#         13 02 4E 4C <- PrintableString "NL"
+# 31 11 <- Set of
+#     30 0F <- Sequence of
+#         06 03 55 04 0A <- OID 2.5.4.10 organizationName (O)
+#         0C 08 50 6F 6C 61 72 53 53 4C <- UTF8String "PolarSSL"
+# 30 19 <- Sequence of (corrupted)
+#     30 17 <- Sequence of
+#         06 03 55 04 03 <- OID 2.5.4.3 commonName (CN)
+#         0C 10 50 6F 6C 61 72 53 53 4C 20 54 65 73 74 20 43 41 <- UTF8String "PolarSSL Test CA"
+#
+# The third 'Set of' is corrupted to instead be a 'Sequence of', causing an
+# error and forcing mbedtls_x509_get_name() to clean up the names it has
+# already allocated.
+#
 X509 Get Name Corrupted DN Mem Leak
 mbedtls_x509_get_name:"310B3009060355040613024E4C3111300F060355040A0C08506F6C617253534C3019301706035504030C10506F6C617253534C2054657374204341":MBEDTLS_ERR_X509_INVALID_NAME + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG