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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/core/utils/DNS.h>
#include <aws/core/utils/StringUtils.h>
namespace Aws
{
namespace Utils
{
bool IsValidDnsLabel(const Aws::String& label)
{
// Valid DNS hostnames are composed of valid DNS labels separated by a period.
// Valid DNS labels are characterized by the following:
// 1- Only contains alphanumeric characters and/or dashes
// 2- Cannot start or end with a dash
// 3- Have a maximum length of 63 characters (the entirety of the domain name should be less than 255 bytes)
if (label.empty())
return false;
if (label.size() > 63)
return false;
if (!StringUtils::IsAlnum(label.front()))
return false; // '-' is not acceptable as the first character
if (!StringUtils::IsAlnum(label.back()))
return false; // '-' is not acceptable as the last character
for (size_t i = 1, e = label.size() - 1; i < e; ++i)
{
auto c = label[i];
if (c != '-' && !StringUtils::IsAlnum(c))
return false;
}
return true;
}
bool IsValidHost(const Aws::String& host)
{
// Valid DNS hostnames are composed of valid DNS labels separated by a period.
auto labels = StringUtils::Split(host, '.');
if (labels.empty())
{
return false;
}
return !std::any_of(labels.begin(), labels.end(), [](const Aws::String& label){ return !IsValidDnsLabel(label); });
}
}
}
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