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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Secure Component */
/** */
/** X.509 Digital Certificates */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_x509.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_x509_common_name_dns_check PORTABLE C */
/* 6.1.6 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function checks a certificate's Common Name against a Top */
/* Level Domain name (TLD) provided by the caller for the purposes of */
/* DNS validation of a remote host. This utility function is intended */
/* to be called from within a certificate validation callback routine */
/* provided by the application. The TLD name should be the top part of */
/* the URL used to access the remote host (the "."-separated string */
/* before the first slash). */
/* */
/* NOTE 1: If the Common Name does not match the provided string, the */
/* "subject alt name" field is compared as well. */
/* */
/* NOTE 2: It is important to understand the format of the common name */
/* (and subject alt name) in expected certificates. For */
/* example, some certificates may use a raw IP address or a */
/* wild card. The DNS TLD string must be formatted such that */
/* it will match the expected values in received certificates. */
/* */
/* INPUT */
/* */
/* certificate Pointer to certificate */
/* dns_tld Top-level domain name */
/* dns_tls_length Length of TLS in bytes */
/* */
/* OUTPUT */
/* */
/* status Validity of certificate */
/* */
/* CALLS */
/* */
/* _nx_secure_x509_extension_find Find extension in certificate */
/* _nx_secure_x509_subject_alt_names_find */
/* Find subject alt names */
/* _nx_secure_x509_wildcard_compare Wildcard compare for names */
/* */
/* CALLED BY */
/* */
/* Application code */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), */
/* resulting in version 6.1 */
/* 04-02-2021 Timothy Stapko Modified comment(s), */
/* removed dependency on TLS, */
/* resulting in version 6.1.6 */
/* */
/**************************************************************************/
UINT _nx_secure_x509_common_name_dns_check(NX_SECURE_X509_CERT *certificate, const UCHAR *dns_tld,
UINT dns_tld_length)
{
INT compare_value;
UINT status;
const UCHAR *common_name;
USHORT common_name_len;
NX_SECURE_X509_EXTENSION alt_name_extension;
/* Get access to our certificate fields. */
common_name = certificate -> nx_secure_x509_distinguished_name.nx_secure_x509_common_name;
common_name_len = certificate -> nx_secure_x509_distinguished_name.nx_secure_x509_common_name_length;
/* Compare the given string against the common name. */
compare_value = _nx_secure_x509_wildcard_compare(dns_tld, dns_tld_length, common_name, common_name_len);
if (compare_value == 0)
{
return(NX_SECURE_X509_SUCCESS);
}
/* Find the subject alt name extension in the certificate. */
status = _nx_secure_x509_extension_find(certificate, &alt_name_extension, NX_SECURE_TLS_X509_TYPE_SUBJECT_ALT_NAME);
/* See if extension present - it is OK if not present! */
if (status == NX_SECURE_X509_SUCCESS)
{
/* Extract the subject alt name string from the parsed extension. */
status = _nx_secure_x509_subject_alt_names_find(&alt_name_extension, dns_tld, dns_tld_length, NX_SECURE_X509_SUB_ALT_NAME_TAG_DNSNAME);
if (status == NX_SECURE_X509_SUCCESS)
{
return(NX_SECURE_X509_SUCCESS);
}
}
/* If we get here, none of the strings matched. */
return(NX_SECURE_X509_CERTIFICATE_DNS_MISMATCH);
}