1/*
2* Copyright 2010-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
3*
4* Licensed under the Apache License, Version 2.0 (the "License").
5* You may not use this file except in compliance with the License.
6* A copy of the License is located at
7*
8* http://aws.amazon.com/apache2.0
9*
10* or in the "license" file accompanying this file. This file is distributed
11* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
12* express or implied. See the License for the specific language governing
13* permissions and limitations under the License.
14*/
15
16#include <aws/core/utils/DNS.h>
17#include <aws/core/utils/StringUtils.h>
18
19namespace Aws
20{
21 namespace Utils
22 {
23 bool IsValidDnsLabel(const Aws::String& label)
24 {
25 // Valid DNS hostnames are composed of valid DNS labels separated by a period.
26 // Valid DNS labels are characterized by the following:
27 // 1- Only contains alphanumeric characters and/or dashes
28 // 2- Cannot start or end with a dash
29 // 3- Have a maximum length of 63 characters (the entirety of the domain name should be less than 255 bytes)
30
31 if (label.empty())
32 return false;
33
34 if (label.size() > 63)
35 return false;
36
37 if (!StringUtils::IsAlnum(label.front()))
38 return false; // '-' is not acceptable as the first character
39
40 if (!StringUtils::IsAlnum(label.back()))
41 return false; // '-' is not acceptable as the last character
42
43 for (size_t i = 1, e = label.size() - 1; i < e; ++i)
44 {
45 auto c = label[i];
46 if (c != '-' && !StringUtils::IsAlnum(c))
47 return false;
48 }
49
50 return true;
51 }
52
53 bool IsValidHost(const Aws::String& host)
54 {
55 // Valid DNS hostnames are composed of valid DNS labels separated by a period.
56 auto labels = StringUtils::Split(host, '.');
57 if (labels.empty())
58 {
59 return false;
60 }
61
62 return !std::any_of(labels.begin(), labels.end(), [](const Aws::String& label){ return !IsValidDnsLabel(label); });
63 }
64 }
65}
66