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Add DNS Server

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This commit is contained in:
me-no-dev 2018-01-18 13:54:51 +02:00
parent 8332a235d6
commit 615c9279f7
4 changed files with 284 additions and 0 deletions
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52
libraries/DNSServer/examples/CaptivePortal/CaptivePortal.ino Normal file
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#include <WiFi.h>
#include <DNSServer.h>
const byte DNS_PORT = 53;
IPAddress apIP(192, 168, 1, 1);
DNSServer dnsServer;
WiFiServer server(80);
String responseHTML = ""
"<!DOCTYPE html><html><head><title>CaptivePortal</title></head><body>"
"<h1>Hello World!</h1><p>This is a captive portal example. All requests will "
"be redirected here.</p></body></html>";
void setup() {
WiFi.mode(WIFI_AP);
WiFi.softAPConfig(apIP, apIP, IPAddress(255, 255, 255, 0));
WiFi.softAP("DNSServer CaptivePortal example");
// if DNSServer is started with "*" for domain name, it will reply with
// provided IP to all DNS request
dnsServer.start(DNS_PORT, "*", apIP);
server.begin();
}
void loop() {
dnsServer.processNextRequest();
WiFiClient client = server.available(); // listen for incoming clients
if (client) {
String currentLine = "";
while (client.connected()) {
if (client.available()) {
char c = client.read();
if (c == '\n') {
if (currentLine.length() == 0) {
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println();
client.print(responseHTML);
break;
} else {
currentLine = "";
}
} else if (c != '\r') {
currentLine += c;
}
}
}
client.stop();
}
}

9
libraries/DNSServer/library.properties Normal file
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name=DNSServer
version=1.1.0
author=Kristijan Novoselić
maintainer=Kristijan Novoselić, <kristijan.novoselic@gmail.com>
sentence=A simple DNS server for ESP32.
paragraph=This library implements a simple DNS server.
category=Communication
url=
architectures=esp32

147
libraries/DNSServer/src/DNSServer.cpp Normal file
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#include "DNSServer.h"
#include <lwip/def.h>
#include <Arduino.h>
DNSServer::DNSServer()
{
_ttl = htonl(60);
_errorReplyCode = DNSReplyCode::NonExistentDomain;
_dnsHeader = NULL;
_buffer = NULL;
_currentPacketSize = 0;
_port = 0;
}
bool DNSServer::start(const uint16_t &port, const String &domainName,
const IPAddress &resolvedIP)
{
_port = port;
_buffer = NULL;
_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();
free(_buffer);
_buffer = NULL;
}
void DNSServer::downcaseAndRemoveWwwPrefix(String &domainName)
{
domainName.toLowerCase();
domainName.replace("www.", "");
}
void DNSServer::processNextRequest()
{
_currentPacketSize = _udp.parsePacket();
if (_currentPacketSize)
{
if (_buffer != NULL) free(_buffer);
_buffer = (unsigned char*)malloc(_currentPacketSize * sizeof(char));
if (_buffer == NULL) return;
_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);
_buffer = NULL;
}
}
bool DNSServer::requestIncludesOnlyOneQuestion()
{
return ntohs(_dnsHeader->QDCount) == 1 &&
_dnsHeader->ANCount == 0 &&
_dnsHeader->NSCount == 0 &&
_dnsHeader->ARCount == 0;
}
String DNSServer::getDomainNameWithoutWwwPrefix()
{
String parsedDomainName = "";
if (_buffer == NULL) return 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()
{
if (_buffer == NULL) return;
_dnsHeader->QR = DNS_QR_RESPONSE;
_dnsHeader->ANCount = _dnsHeader->QDCount;
_dnsHeader->QDCount = 0;
_udp.beginPacket(_udp.remoteIP(), _udp.remotePort());
_udp.write(_buffer, _currentPacketSize);
_udp.write((unsigned char*)&_ttl, 4);
_udp.write((uint8_t)0);
_udp.write((uint8_t)4);
_udp.write(_resolvedIP, 4);
_udp.endPacket();
}
void DNSServer::replyWithCustomCode()
{
if (_buffer == NULL) return;
_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();
}

76
libraries/DNSServer/src/DNSServer.h Normal file
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#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
union {
struct {
uint16_t RD : 1; // recursion desired
uint16_t TC : 1; // truncated message
uint16_t AA : 1; // authoritive answer
uint16_t OPCode : 4; // message_type
uint16_t QR : 1; // query/response flag
uint16_t RCode : 4; // response code
uint16_t Z : 3; // its z! reserved
uint16_t RA : 1; // recursion available
};
uint16_t Flags;
};
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