1 /*
2  *  Copyright (c) 2023, The OpenThread Authors.
3  *  All rights reserved.
4  *
5  *  Redistribution and use in source and binary forms, with or without
6  *  modification, are permitted provided that the following conditions are met:
7  *  1. Redistributions of source code must retain the above copyright
8  *     notice, this list of conditions and the following disclaimer.
9  *  2. Redistributions in binary form must reproduce the above copyright
10  *     notice, this list of conditions and the following disclaimer in the
11  *     documentation and/or other materials provided with the distribution.
12  *  3. Neither the name of the copyright holder nor the
13  *     names of its contributors may be used to endorse or promote products
14  *     derived from this software without specific prior written permission.
15  *
16  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17  *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20  *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23  *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24  *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25  *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26  *  POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #ifndef POSIX_PLATFORM_RESOLVER_HPP_
30 #define POSIX_PLATFORM_RESOLVER_HPP_
31 
32 #include <openthread/platform/dns.h>
33 
34 #include <arpa/inet.h>
35 #include <sys/select.h>
36 
37 #if OPENTHREAD_CONFIG_DNS_UPSTREAM_QUERY_ENABLE
38 
39 namespace ot {
40 namespace Posix {
41 
42 class Resolver
43 {
44 public:
45     constexpr static ssize_t kMaxDnsMessageSize           = 512;
46     constexpr static ssize_t kMaxUpstreamTransactionCount = 16;
47     constexpr static ssize_t kMaxUpstreamServerCount      = 3;
48 
49     /**
50      * This method initialize the upstream DNS resolver.
51      *
52      */
53     void Init(void);
54 
55     /**
56      * Sends the query to the upstream.
57      *
58      * @param[in] aTxn   A pointer to the OpenThread upstream DNS query transaction.
59      * @param[in] aQuery A pointer to a message for the payload of the DNS query.
60      *
61      */
62     void Query(otPlatDnsUpstreamQuery *aTxn, const otMessage *aQuery);
63 
64     /**
65      * Cancels a upstream DNS query transaction.
66      *
67      * @param[in] aTxn   A pointer to the OpenThread upstream DNS query transaction.
68      *
69      */
70     void Cancel(otPlatDnsUpstreamQuery *aTxn);
71 
72     /**
73      * Updates the file descriptor sets with file descriptors used by the radio driver.
74      *
75      * @param[in,out]  aReadFdSet   A reference to the read file descriptors.
76      * @param[in,out]  aErrorFdSet  A reference to the error file descriptors.
77      * @param[in,out]  aMaxFd       A reference to the max file descriptor.
78      * @param[in,out]  aTimeout     A reference to the timeout.
79      *
80      */
81     void UpdateFdSet(fd_set *aReadFdSet, fd_set *aErrorFdSet, int *aMaxFd);
82 
83     /**
84      * Handles the result of select.
85      *
86      * @param[in]  aReadFdSet   A reference to the read file descriptors.
87      * @param[in]  aErrorFdSet  A reference to the error file descriptors.
88      *
89      */
90     void Process(const fd_set *aReadFdSet, const fd_set *aErrorFdSet);
91 
92 private:
93     static constexpr uint64_t kDnsServerListNullCacheTimeoutMs = 1 * 60 * 1000;  // 1 minute
94     static constexpr uint64_t kDnsServerListCacheTimeoutMs     = 10 * 60 * 1000; // 10 minutes
95 
96     struct Transaction
97     {
98         otPlatDnsUpstreamQuery *mThreadTxn;
99         int                     mUdpFd;
100     };
101 
102     Transaction *GetTransaction(int aFd);
103     Transaction *GetTransaction(otPlatDnsUpstreamQuery *aThreadTxn);
104     Transaction *AllocateTransaction(otPlatDnsUpstreamQuery *aThreadTxn);
105 
106     void ForwardResponse(Transaction *aTxn);
107     void CloseTransaction(Transaction *aTxn);
108     void FinishTransaction(int aFd);
109     void TryRefreshDnsServerList(void);
110     void LoadDnsServerListFromConf(void);
111 
112     int       mUpstreamDnsServerCount = 0;
113     in_addr_t mUpstreamDnsServerList[kMaxUpstreamServerCount];
114     uint64_t  mUpstreamDnsServerListFreshness = 0;
115 
116     Transaction mUpstreamTransaction[kMaxUpstreamTransactionCount];
117 };
118 
119 } // namespace Posix
120 } // namespace ot
121 
122 #endif // OPENTHREAD_CONFIG_DNS_UPSTREAM_QUERY_ENABLE
123 
124 #endif // POSIX_PLATFORM_RESOLVER_HPP_
125