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‎ESP32S2_TFT_AdBlocker/.feather_esp32s2_tft.test.only

Whitespace-only changes.

‎ESP32S2_TFT_AdBlocker/AdBlockerDNSServer.cpp

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#include "AdBlockerDNSServer.h"
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#include <lwip/def.h>
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#include <Arduino.h>
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//// ESP32_AdBlocker
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// call back to check if domain blocked and receive IP address to be used
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IPAddress checkBlocklist(const char* domainName);
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//// ESP32_AdBlocker
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DNSServer::DNSServer()
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{
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_ttl = htonl(DNS_DEFAULT_TTL);
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_errorReplyCode = DNSReplyCode::NonExistentDomain;
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_dnsHeader = (DNSHeader*) malloc( sizeof(DNSHeader) ) ;
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_dnsQuestion = (DNSQuestion*) malloc( sizeof(DNSQuestion) ) ;
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_buffer = NULL;
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_currentPacketSize = 0;
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_port = 0;
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}
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bool DNSServer::start(const uint16_t &port, const String &domainName,
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const IPAddress &resolvedIP)
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{
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_port = port;
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_buffer = NULL;
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_domainName = domainName;
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_resolvedIP[0] = resolvedIP[0];
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_resolvedIP[1] = resolvedIP[1];
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_resolvedIP[2] = resolvedIP[2];
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_resolvedIP[3] = resolvedIP[3];
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downcaseAndRemoveWwwPrefix(_domainName);
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return _udp.begin(_port) == 1;
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}
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void DNSServer::setErrorReplyCode(const DNSReplyCode &replyCode)
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{
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_errorReplyCode = replyCode;
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}
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void DNSServer::setTTL(const uint32_t &ttl)
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{
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_ttl = htonl(ttl);
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}
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void DNSServer::stop()
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{
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_udp.stop();
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free(_buffer);
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_buffer = NULL;
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}
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void DNSServer::downcaseAndRemoveWwwPrefix(String &domainName)
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{
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domainName.toLowerCase();
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domainName.replace("www.", "");
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}
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void DNSServer::processNextRequest()
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{
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_currentPacketSize = _udp.parsePacket();
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if (_currentPacketSize)
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{
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// Allocate buffer for the DNS query
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if (_buffer != NULL)
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free(_buffer);
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_buffer = (unsigned char*)malloc(_currentPacketSize * sizeof(char));
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if (_buffer == NULL)
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return;
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// Put the packet received in the buffer and get DNS header (beginning of message)
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// and the question
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_udp.read(_buffer, _currentPacketSize);
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memcpy( _dnsHeader, _buffer, DNS_HEADER_SIZE ) ;
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if ( requestIncludesOnlyOneQuestion() )
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{
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// The QName has a variable length, maximum 255 bytes and is comprised of multiple labels.
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// Each label contains a byte to describe its length and the label itself. The list of
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// labels terminates with a zero-valued byte. In "github.com", we have two labels "github" & "com"
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// Iterate through the labels and copy them as they come into a single buffer (for simplicity's sake)
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_dnsQuestion->QNameLength = 0 ;
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while ( _buffer[ DNS_HEADER_SIZE + _dnsQuestion->QNameLength ] != 0 )
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{
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memcpy( (void*) &_dnsQuestion->QName[_dnsQuestion->QNameLength], (void*) &_buffer[DNS_HEADER_SIZE + _dnsQuestion->QNameLength], _buffer[DNS_HEADER_SIZE + _dnsQuestion->QNameLength] + 1 ) ;
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_dnsQuestion->QNameLength += _buffer[DNS_HEADER_SIZE + _dnsQuestion->QNameLength] + 1 ;
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}
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_dnsQuestion->QName[_dnsQuestion->QNameLength] = 0 ;
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_dnsQuestion->QNameLength++ ;
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// Copy the QType and QClass
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memcpy( &_dnsQuestion->QType, (void*) &_buffer[DNS_HEADER_SIZE + _dnsQuestion->QNameLength], sizeof(_dnsQuestion->QType) ) ;
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memcpy( &_dnsQuestion->QClass, (void*) &_buffer[DNS_HEADER_SIZE + _dnsQuestion->QNameLength + sizeof(_dnsQuestion->QType)], sizeof(_dnsQuestion->QClass) ) ;
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}
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if (_dnsHeader->QR == DNS_QR_QUERY &&
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_dnsHeader->OPCode == DNS_OPCODE_QUERY &&
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requestIncludesOnlyOneQuestion() &&
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(_domainName == "*" || getDomainNameWithoutWwwPrefix() == _domainName)
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)
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{
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//// ESP32_AdBlocker
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IPAddress IPtoUse = checkBlocklist(getDomainNameWithoutWwwPrefix().c_str());
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for (int i=0; i<4; i++) _resolvedIP[i] = IPtoUse[i];
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//// ESP32_AdBlocker
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replyWithIP();
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}
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else if (_dnsHeader->QR == DNS_QR_QUERY)
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{
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replyWithCustomCode();
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}
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free(_buffer);
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_buffer = NULL;
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}
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}
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bool DNSServer::requestIncludesOnlyOneQuestion()
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{
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return ntohs(_dnsHeader->QDCount) == 1 &&
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_dnsHeader->ANCount == 0 &&
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_dnsHeader->NSCount == 0 &&
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_dnsHeader->ARCount == 0;
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}
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String DNSServer::getDomainNameWithoutWwwPrefix()
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{
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// Error checking : if the buffer containing the DNS request is a null pointer, return an empty domain
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String parsedDomainName = "";
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if (_buffer == NULL)
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return parsedDomainName;
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// Set the start of the domain just after the header (12 bytes). If equal to null character, return an empty domain
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unsigned char *start = _buffer + DNS_OFFSET_DOMAIN_NAME;
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if (*start == 0)
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{
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return parsedDomainName;
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}
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int pos = 0;
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while(true)
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{
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unsigned char labelLength = *(start + pos);
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for(int i = 0; i < labelLength; i++)
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{
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pos++;
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parsedDomainName += (char)*(start + pos);
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}
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pos++;
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if (*(start + pos) == 0)
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{
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downcaseAndRemoveWwwPrefix(parsedDomainName);
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return parsedDomainName;
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}
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else
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{
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parsedDomainName += ".";
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}
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}
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}
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void DNSServer::replyWithIP()
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{
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if (_buffer == NULL) return;
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_udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
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// Change the type of message to a response and set the number of answers equal to
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// the number of questions in the header
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_dnsHeader->QR = DNS_QR_RESPONSE;
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_dnsHeader->ANCount = _dnsHeader->QDCount;
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_udp.write( (unsigned char*) _dnsHeader, DNS_HEADER_SIZE ) ;
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// Write the question
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_udp.write(_dnsQuestion->QName, _dnsQuestion->QNameLength) ;
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_udp.write( (unsigned char*) &_dnsQuestion->QType, 2 ) ;
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_udp.write( (unsigned char*) &_dnsQuestion->QClass, 2 ) ;
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// Write the answer
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// Use DNS name compression : instead of repeating the name in this RNAME occurence,
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// set the two MSB of the byte corresponding normally to the length to 1. The following
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// 14 bits must be used to specify the offset of the domain name in the message
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// (<255 here so the first byte has the 6 LSB at 0)
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_udp.write((uint8_t) 0xC0);
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_udp.write((uint8_t) DNS_OFFSET_DOMAIN_NAME);
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// DNS type A : host address, DNS class IN for INternet, returning an IPv4 address
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uint16_t answerType = htons(DNS_TYPE_A), answerClass = htons(DNS_CLASS_IN), answerIPv4 = htons(DNS_RDLENGTH_IPV4) ;
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_udp.write((unsigned char*) &answerType, 2 );
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_udp.write((unsigned char*) &answerClass, 2 );
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_udp.write((unsigned char*) &_ttl, 4); // DNS Time To Live
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_udp.write((unsigned char*) &answerIPv4, 2 );
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_udp.write(_resolvedIP, sizeof(_resolvedIP)); // The IP address to return
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_udp.endPacket();
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#ifdef DEBUG_ESP_DNS
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DBG_OUTPUT_PORT.printf("DNS responds: %s for %s\n",
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IPAddress(_resolvedIP).toString().c_str(), getDomainNameWithoutWwwPrefix().c_str() );
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#endif
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}
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void DNSServer::replyWithCustomCode()
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{
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if (_buffer == NULL) return;
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_dnsHeader->QR = DNS_QR_RESPONSE;
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_dnsHeader->RCode = (unsigned char)_errorReplyCode;
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_dnsHeader->QDCount = 0;
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_udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
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_udp.write(_buffer, sizeof(DNSHeader));
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_udp.endPacket();
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}

‎ESP32S2_TFT_AdBlocker/AdBlockerDNSServer.h

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#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

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