694c3a453f
* Retrieve some code from what has been done on the ESP8266. Clarify a bit the signification of several bytes in the response. * Add the type and class as members of the DNS class for an eventual future use. * Clarify the sense of a magic number present in DNS server. * A bit of aesthetics for the DNS server. * Add a structure for the DNS question, use it DNS server to store the question data and to create the DNS answer from scratch.
109 lines
2.7 KiB
C++
109 lines
2.7 KiB
C++
#ifndef DNSServer_h
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#define DNSServer_h
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#include <WiFiUdp.h>
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#define DNS_QR_QUERY 0
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#define DNS_QR_RESPONSE 1
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#define DNS_OPCODE_QUERY 0
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#define DNS_DEFAULT_TTL 60 // Default Time To Live : time interval in seconds that the resource record should be cached before being discarded
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#define DNS_OFFSET_DOMAIN_NAME 12 // Offset in bytes to reach the domain name in the DNS message
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#define DNS_HEADER_SIZE 12
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enum class DNSReplyCode
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{
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NoError = 0,
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FormError = 1,
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ServerFailure = 2,
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NonExistentDomain = 3,
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NotImplemented = 4,
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Refused = 5,
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YXDomain = 6,
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YXRRSet = 7,
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NXRRSet = 8
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};
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enum DNSType
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{
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DNS_TYPE_A = 1, // Host Address
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DNS_TYPE_AAAA = 28, // IPv6 Address
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DNS_TYPE_SOA = 6, // Start Of a zone of Authority
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DNS_TYPE_PTR = 12, // Domain name PoinTeR
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DNS_TYPE_DNAME = 39 // Delegation Name
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} ;
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enum DNSClass
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{
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DNS_CLASS_IN = 1, // INternet
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DNS_CLASS_CH = 3 // CHaos
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} ;
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enum DNSRDLength
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{
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DNS_RDLENGTH_IPV4 = 4 // 4 bytes for an IPv4 address
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} ;
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struct DNSHeader
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{
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uint16_t ID; // identification number
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union {
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struct {
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uint16_t RD : 1; // recursion desired
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uint16_t TC : 1; // truncated message
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uint16_t AA : 1; // authoritive answer
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uint16_t OPCode : 4; // message_type
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uint16_t QR : 1; // query/response flag
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uint16_t RCode : 4; // response code
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uint16_t Z : 3; // its z! reserved
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uint16_t RA : 1; // recursion available
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};
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uint16_t Flags;
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};
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uint16_t QDCount; // number of question entries
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uint16_t ANCount; // number of answer entries
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uint16_t NSCount; // number of authority entries
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uint16_t ARCount; // number of resource entries
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};
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struct DNSQuestion
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{
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uint8_t QName[255] ;
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int8_t QNameLength ;
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uint16_t QType ;
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uint16_t QClass ;
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} ;
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class DNSServer
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{
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public:
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DNSServer();
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void processNextRequest();
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void setErrorReplyCode(const DNSReplyCode &replyCode);
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void setTTL(const uint32_t &ttl);
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// Returns true if successful, false if there are no sockets available
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bool start(const uint16_t &port,
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const String &domainName,
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const IPAddress &resolvedIP);
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// stops the DNS server
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void stop();
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private:
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WiFiUDP _udp;
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uint16_t _port;
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String _domainName;
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unsigned char _resolvedIP[4];
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int _currentPacketSize;
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unsigned char* _buffer;
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DNSHeader* _dnsHeader;
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uint32_t _ttl;
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DNSReplyCode _errorReplyCode;
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DNSQuestion* _dnsQuestion ;
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void downcaseAndRemoveWwwPrefix(String &domainName);
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String getDomainNameWithoutWwwPrefix();
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bool requestIncludesOnlyOneQuestion();
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void replyWithIP();
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void replyWithCustomCode();
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};
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#endif |