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ESP8266 : Create a WiFi access point and provide a DNS and web server on it, catch all traffic
/* Create a WiFi access point and provide a web server on it. */
#include <ESP8266WiFi.h>
#include "./DNSServer.h" // Patched lib
#include <ESP8266WebServer.h>
const byte DNS_PORT = 53; // Capture DNS requests on port 53
IPAddress apIP(10, 10, 10, 1); // Private network for server
DNSServer dnsServer; // Create the DNS object
ESP8266WebServer webServer(80); // HTTP server
String responseHTML = "<!DOCTYPE html>"
"<html lang=\"en\">"
"<head>"
"<meta charset=\"utf-8\">"
"<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">"
"<title>Internet of Bottles</title>"
"</head>"
"<body>"
"<p>I'm just a stupid bottle with WiFi.</p>"
"</body>"
"</html>";
void setup() {
// turn the LED on (HIGH is the voltage level)
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, HIGH);
// configure access point
WiFi.mode(WIFI_AP);
WiFi.softAPConfig(apIP, apIP, IPAddress(255, 255, 255, 0));
WiFi.softAP("IoT --- Free WiFi"); // WiFi name
// if DNSServer is started with "*" for domain name, it will reply with
// provided IP to all DNS request
dnsServer.start(DNS_PORT, "*", apIP);
// replay to all requests with same HTML
webServer.onNotFound([]() {
webServer.send(200, "text/html", responseHTML);
});
webServer.begin();
}
void loop() {
dnsServer.processNextRequest();
webServer.handleClient();
}
#include "./DNSServer.h"
#include <lwip/def.h>
#include <Arduino.h>
#define DEBUG
#define DEBUG_OUTPUT Serial
DNSServer::DNSServer()
{
_ttl = htonl(60);
_errorReplyCode = DNSReplyCode::NonExistentDomain;
}
bool DNSServer::start(const uint16_t &port, const String &domainName,
const IPAddress &resolvedIP)
{
_port = port;
_domainName = domainName;
_resolvedIP[0] = resolvedIP[0];
_resolvedIP[1] = resolvedIP[1];
_resolvedIP[2] = resolvedIP[2];
_resolvedIP[3] = resolvedIP[3];
downcaseAndRemoveWwwPrefix(_domainName);
return _udp.begin(_port) == 1;
}
void DNSServer::setErrorReplyCode(const DNSReplyCode &replyCode)
{
_errorReplyCode = replyCode;
}
void DNSServer::setTTL(const uint32_t &ttl)
{
_ttl = htonl(ttl);
}
void DNSServer::stop()
{
_udp.stop();
}
void DNSServer::downcaseAndRemoveWwwPrefix(String &domainName)
{
domainName.toLowerCase();
domainName.replace("www.", "");
}
void DNSServer::processNextRequest()
{
_currentPacketSize = _udp.parsePacket();
if (_currentPacketSize)
{
_buffer = (unsigned char*)malloc(_currentPacketSize * sizeof(char));
_udp.read(_buffer, _currentPacketSize);
_dnsHeader = (DNSHeader*) _buffer;
if (_dnsHeader->QR == DNS_QR_QUERY &&
_dnsHeader->OPCode == DNS_OPCODE_QUERY &&
requestIncludesOnlyOneQuestion() &&
(_domainName == "*" || getDomainNameWithoutWwwPrefix() == _domainName)
)
{
replyWithIP();
}
else if (_dnsHeader->QR == DNS_QR_QUERY)
{
replyWithCustomCode();
}
free(_buffer);
}
}
bool DNSServer::requestIncludesOnlyOneQuestion()
{
return ntohs(_dnsHeader->QDCount) == 1 &&
_dnsHeader->ANCount == 0 &&
_dnsHeader->NSCount == 0 &&
_dnsHeader->ARCount == 0;
}
String DNSServer::getDomainNameWithoutWwwPrefix()
{
String parsedDomainName = "";
unsigned char *start = _buffer + 12;
if (*start == 0)
{
return parsedDomainName;
}
int pos = 0;
while(true)
{
unsigned char labelLength = *(start + pos);
for(int i = 0; i < labelLength; i++)
{
pos++;
parsedDomainName += (char)*(start + pos);
}
pos++;
if (*(start + pos) == 0)
{
downcaseAndRemoveWwwPrefix(parsedDomainName);
return parsedDomainName;
}
else
{
parsedDomainName += ".";
}
}
}
void DNSServer::replyWithIP()
{
_dnsHeader->QR = DNS_QR_RESPONSE;
_dnsHeader->ANCount = _dnsHeader->QDCount;
_dnsHeader->QDCount = _dnsHeader->QDCount;
//_dnsHeader->RA = 1;
_udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
_udp.write(_buffer, _currentPacketSize);
_udp.write((uint8_t)192); // answer name is a pointer
_udp.write((uint8_t)12); // pointer to offset at 0x00c
_udp.write((uint8_t)0); // 0x0001 answer is type A query (host address)
_udp.write((uint8_t)1);
_udp.write((uint8_t)0); //0x0001 answer is class IN (internet address)
_udp.write((uint8_t)1);
_udp.write((unsigned char*)&_ttl, 4);
// Length of RData is 4 bytes (because, in this case, RData is IPv4)
_udp.write((uint8_t)0);
_udp.write((uint8_t)4);
_udp.write(_resolvedIP, sizeof(_resolvedIP));
_udp.endPacket();
#ifdef DEBUG
DEBUG_OUTPUT.print("DNS responds: ");
DEBUG_OUTPUT.print(_resolvedIP[0]);
DEBUG_OUTPUT.print(".");
DEBUG_OUTPUT.print(_resolvedIP[1]);
DEBUG_OUTPUT.print(".");
DEBUG_OUTPUT.print(_resolvedIP[2]);
DEBUG_OUTPUT.print(".");
DEBUG_OUTPUT.print(_resolvedIP[3]);
DEBUG_OUTPUT.print(" for ");
DEBUG_OUTPUT.println(getDomainNameWithoutWwwPrefix());
#endif
}
void DNSServer::replyWithCustomCode()
{
_dnsHeader->QR = DNS_QR_RESPONSE;
_dnsHeader->RCode = (unsigned char)_errorReplyCode;
_dnsHeader->QDCount = 0;
_udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
_udp.write(_buffer, sizeof(DNSHeader));
_udp.endPacket();
}
#ifndef DNSServer_h
#define DNSServer_h
#include <WiFiUdp.h>
#define DNS_QR_QUERY 0
#define DNS_QR_RESPONSE 1
#define DNS_OPCODE_QUERY 0
enum class DNSReplyCode
{
NoError = 0,
FormError = 1,
ServerFailure = 2,
NonExistentDomain = 3,
NotImplemented = 4,
Refused = 5,
YXDomain = 6,
YXRRSet = 7,
NXRRSet = 8
};
struct DNSHeader
{
uint16_t ID; // identification number
unsigned char RD : 1; // recursion desired
unsigned char TC : 1; // truncated message
unsigned char AA : 1; // authoritive answer
unsigned char OPCode : 4; // message_type
unsigned char QR : 1; // query/response flag
unsigned char RCode : 4; // response code
unsigned char Z : 3; // its z! reserved
unsigned char RA : 1; // recursion available
uint16_t QDCount; // number of question entries
uint16_t ANCount; // number of answer entries
uint16_t NSCount; // number of authority entries
uint16_t ARCount; // number of resource entries
};
class DNSServer
{
public:
DNSServer();
void processNextRequest();
void setErrorReplyCode(const DNSReplyCode &replyCode);
void setTTL(const uint32_t &ttl);
// Returns true if successful, false if there are no sockets available
bool start(const uint16_t &port,
const String &domainName,
const IPAddress &resolvedIP);
// stops the DNS server
void stop();
private:
WiFiUDP _udp;
uint16_t _port;
String _domainName;
unsigned char _resolvedIP[4];
int _currentPacketSize;
unsigned char* _buffer;
DNSHeader* _dnsHeader;
uint32_t _ttl;
DNSReplyCode _errorReplyCode;
void downcaseAndRemoveWwwPrefix(String &domainName);
String getDomainNameWithoutWwwPrefix();
bool requestIncludesOnlyOneQuestion();
void replyWithIP();
void replyWithCustomCode();
};
#endif
@MarcoCiau

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MarcoCiau commented Oct 21, 2019

Great! It's work for me. Thanks a lot!

@TiagoCN

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TiagoCN commented Oct 30, 2019

No license?

@kainzjo1

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kainzjo1 commented Nov 11, 2019

What do I need to do to get a good readable url for the webserver? (like "http:\IoT.local")

@TiagoCN

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TiagoCN commented Nov 12, 2019

What do I need to do to get a good readable url for the webserver? (like "http:\IoT.local")

Take a look at https://github.com/esp8266/Arduino/tree/master/libraries/ESP8266mDNS

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