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MDNS.cpp
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// Copyright (C) 2010 Georg Kaindl
// http://gkaindl.com
//
// This file is part of Arduino EthernetBonjour.
//
// EthernetBonjour is free software: you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License
// as published by the Free Software Foundation, either version 3 of
// the License, or (at your option) any later version.
//
// EthernetBonjour is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with EthernetBonjour. If not, see
// <http://www.gnu.org/licenses/>.
//
#define HAS_SERVICE_REGISTRATION 1 // disabling saves about 1.25 kilobytes
#define HAS_NAME_BROWSING 1 // disable together with above, additionally saves about 4.3 kilobytes
#include <string.h>
#include <stdlib.h>
#include <Arduino.h>
#include <Udp.h>
extern "C" {
#include <utility/EthernetUtil.h>
}
#include "MDNS.h"
#define MDNS_DEFAULT_NAME "arduino"
#define MDNS_TLD ".local"
#define DNS_SD_SERVICE "_services._dns-sd._udp.local"
#define MDNS_SERVER_PORT (5353)
#define MDNS_NQUERY_RESEND_TIME (1000) // 1 second, name query resend timeout
#define MDNS_SQUERY_RESEND_TIME (10000) // 10 seconds, service query resend timeout
#define MDNS_RESPONSE_TTL (120) // two minutes (in seconds)
#define MDNS_MAX_SERVICES_PER_PACKET (6)
//#define _BROKEN_MALLOC_ 1
#undef _USE_MALLOC_
static uint8_t mdnsMulticastIPAddr[] = { 224, 0, 0, 251 };
//static uint8_t mdnsHWAddr[] = { 0x01, 0x00, 0x5e, 0x00, 0x00, 0xfb };
typedef enum _MDNSPacketType_t {
MDNSPacketTypeMyIPAnswer,
MDNSPacketTypeNoIPv6AddrAvailable,
MDNSPacketTypeServiceRecord,
MDNSPacketTypeServiceRecordRelease,
MDNSPacketTypeNameQuery,
MDNSPacketTypeServiceQuery,
} MDNSPacketType_t;
typedef struct _DNSHeader_t {
uint16_t xid;
uint8_t recursionDesired:1;
uint8_t truncated:1;
uint8_t authoritiveAnswer:1;
uint8_t opCode:4;
uint8_t queryResponse:1;
uint8_t responseCode:4;
uint8_t checkingDisabled:1;
uint8_t authenticatedData:1;
uint8_t zReserved:1;
uint8_t recursionAvailable:1;
uint16_t queryCount;
uint16_t answerCount;
uint16_t authorityCount;
uint16_t additionalCount;
} __attribute__((__packed__)) DNSHeader_t;
typedef enum _DNSOpCode_t {
DNSOpQuery = 0,
DNSOpIQuery = 1,
DNSOpStatus = 2,
DNSOpNotify = 4,
DNSOpUpdate = 5
} DNSOpCode_t;
// for some reason, I get data corruption issues with normal malloc() on arduino 0017
void* my_malloc(unsigned s)
{
#if defined(_BROKEN_MALLOC_)
char* b = (char*)malloc(s+2);
if (b)
b++;
return (void*)b;
#else
return malloc(s);
#endif
}
void my_free(void* ptr)
{
#if defined(_BROKEN_MALLOC_)
char* b = (char*)ptr;
if (b)
b--;
free(b);
#else
free(ptr);
#endif
}
MDNS::MDNS(UDP& udp)
{
memset(&this->_mdnsData, 0, sizeof(MDNSDataInternal_t));
memset(&this->_serviceRecords, 0, sizeof(this->_serviceRecords));
this->_udp = &udp;
this->_state = MDNSStateIdle;
// this->_sock = -1;
this->_name = NULL;
this->_resolveNames[0] = NULL;
this->_resolveNames[1] = NULL;
this->_lastAnnounceMillis = 0;
}
MDNS::~MDNS()
{
this->_udp->stop();
}
// return values:
// 1 on success
// 0 otherwise
int MDNS::begin(const IPAddress& ip, const char* name)
{
// if we were called very soon after the board was booted, we need to give the
// EthernetShield (WIZnet) some time to come up. Hence, we delay until millis() is at
// least 3000. This is necessary, so that if we need to add a service record directly
// after begin, the announce packet does not get lost in the bowels of the WIZnet chip.
while (millis() < 3000) delay(100);
_ipAddress = ip;
int statusCode = 0;
statusCode = this->setName(name);
if (statusCode)
statusCode = this->_udp->beginMulticast(mdnsMulticastIPAddr, MDNS_SERVER_PORT);
return statusCode;
}
// return values:
// 1 on success
// 0 otherwise
int MDNS::begin(const IPAddress& ip)
{
return this->begin(ip, MDNS_DEFAULT_NAME);
}
// return values:
// 1 on success
// 0 otherwise
int MDNS::_initQuery(uint8_t idx, const char* name, unsigned long timeout)
{
int statusCode = 0;
if (NULL == this->_resolveNames[idx] && NULL != ((0==idx) ? (void*)this->_nameFoundCallback :
(void*)this->_serviceFoundCallback)) {
this->_resolveNames[idx] = (uint8_t*)name;
if (timeout)
this->_resolveTimeouts[idx] = millis() + timeout;
else
this->_resolveTimeouts[idx] = 0;
statusCode = (MDNSSuccess == this->_sendMDNSMessage(0,
0,
(idx == 0) ? MDNSPacketTypeNameQuery :
MDNSPacketTypeServiceQuery,
0));
} else
my_free((void*)name);
return statusCode;
}
void MDNS::_cancelQuery(uint8_t idx)
{
if (NULL != this->_resolveNames[idx]) {
my_free(this->_resolveNames[idx]);
this->_resolveNames[idx] = NULL;
}
}
// return values:
// 1 on success
// 0 otherwise
int MDNS::resolveName(const char* name, unsigned long timeout)
{
this->cancelResolveName();
char* n = (char*)my_malloc(strlen(name) + 7);
if (NULL == n)
return 0;
strcpy(n, name);
strcat(n, MDNS_TLD);
return this->_initQuery(0, n, timeout);
}
void MDNS::setNameResolvedCallback(MDNSNameFoundCallback newCallback)
{
this->_nameFoundCallback = newCallback;
}
void MDNS::cancelResolveName()
{
this->_cancelQuery(0);
}
int MDNS::isResolvingName()
{
return (NULL != this->_resolveNames[0]);
}
void MDNS::setServiceFoundCallback(MDNSServiceFoundCallback newCallback)
{
this->_serviceFoundCallback = newCallback;
}
// return values:
// 1 on success
// 0 otherwise
int MDNS::startDiscoveringService(const char* serviceName,
MDNSServiceProtocol_t proto,
unsigned long timeout)
{
this->stopDiscoveringService();
char* n = (char*)my_malloc(strlen(serviceName));
if (NULL == n)
return 0;
strcpy(n, serviceName);
const uint8_t* srv_type = this->_postfixForProtocol(proto);
if (srv_type)
strcat(n, (const char*)srv_type);
this->_resolveServiceProto = proto;
return this->_initQuery(1, n, timeout);
}
void MDNS::stopDiscoveringService()
{
this->_cancelQuery(1);
}
int MDNS::isDiscoveringService()
{
return (NULL != this->_resolveNames[1]);
}
// return value:
// A DNSError_t (DNSSuccess on success, something else otherwise)
// in "int" mode: positive on success, negative on error
MDNSError_t MDNS::_sendMDNSMessage(uint32_t /*peerAddress*/, uint32_t xid, int type,
int serviceRecord)
{
MDNSError_t statusCode = MDNSSuccess;
uint16_t ptr = 0;
#if defined(_USE_MALLOC_)
DNSHeader_t* dnsHeader = NULL;
#else
DNSHeader_t dnsHeaderBuf;
DNSHeader_t* dnsHeader = &dnsHeaderBuf;
#endif
uint8_t* buf;
#if defined(_USE_MALLOC_)
dnsHeader = (DNSHeader_t*)my_malloc(sizeof(DNSHeader_t));
if (NULL == dnsHeader) {
statusCode = MDNSOutOfMemory;
goto errorReturn;
}
#endif
memset(dnsHeader, 0, sizeof(DNSHeader_t));
dnsHeader->xid = ethutil_htons(xid);
dnsHeader->opCode = DNSOpQuery;
switch (type) {
case MDNSPacketTypeServiceRecordRelease:
case MDNSPacketTypeMyIPAnswer:
dnsHeader->answerCount = ethutil_htons(1);
dnsHeader->queryResponse = 1;
dnsHeader->authoritiveAnswer = 1;
break;
case MDNSPacketTypeServiceRecord:
dnsHeader->answerCount = ethutil_htons(4);
dnsHeader->additionalCount = ethutil_htons(1);
dnsHeader->queryResponse = 1;
dnsHeader->authoritiveAnswer = 1;
break;
case MDNSPacketTypeNameQuery:
case MDNSPacketTypeServiceQuery:
dnsHeader->queryCount = ethutil_htons(1);
break;
case MDNSPacketTypeNoIPv6AddrAvailable:
dnsHeader->queryCount = ethutil_htons(1);
dnsHeader->additionalCount = ethutil_htons(1);
dnsHeader->responseCode = 0x03;
dnsHeader->authoritiveAnswer = 1;
dnsHeader->queryResponse = 1;
break;
}
this->_udp->beginPacket(mdnsMulticastIPAddr,MDNS_SERVER_PORT);
this->_udp->write((uint8_t*)dnsHeader,sizeof(DNSHeader_t));
ptr += sizeof(DNSHeader_t);
buf = (uint8_t*)dnsHeader;
// construct the answer section
switch (type) {
case MDNSPacketTypeMyIPAnswer: {
this->_writeMyIPAnswerRecord(&ptr, buf, sizeof(DNSHeader_t));
break;
}
#if defined(HAS_SERVICE_REGISTRATION) && HAS_SERVICE_REGISTRATION
case MDNSPacketTypeServiceRecord: {
// SRV location record
this->_writeServiceRecordName(serviceRecord, &ptr, buf, sizeof(DNSHeader_t), 0);
buf[0] = 0x00;
buf[1] = 0x21; // SRV record
buf[2] = 0x80; // cache flush
buf[3] = 0x01; // class IN
// ttl
*((uint32_t*)&buf[4]) = ethutil_htonl(MDNS_RESPONSE_TTL);
// data length
*((uint16_t*)&buf[8]) = ethutil_htons(8 + strlen((char*)this->_name));
this->_udp->write((uint8_t*)buf,10);
ptr += 10;
// priority and weight
buf[0] = buf[1] = buf[2] = buf[3] = 0;
// port
*((uint16_t*)&buf[4]) = ethutil_htons(this->_serviceRecords[serviceRecord]->port);
this->_udp->write((uint8_t*)buf,6);
ptr += 6;
// target
this->_writeDNSName(this->_name, &ptr, buf, sizeof(DNSHeader_t), 1);
// TXT record
this->_writeServiceRecordName(serviceRecord, &ptr, buf, sizeof(DNSHeader_t), 0);
buf[0] = 0x00;
buf[1] = 0x10; // TXT record
buf[2] = 0x80; // cache flush
buf[3] = 0x01; // class IN
// ttl
*((uint32_t*)&buf[4]) = ethutil_htonl(MDNS_RESPONSE_TTL);
this->_udp->write((uint8_t*)buf,8);
ptr += 8;
// data length && text
if (NULL == this->_serviceRecords[serviceRecord]->textContent) {
buf[0] = 0x00;
buf[1] = 0x01;
buf[2] = 0x00;
this->_udp->write((uint8_t*)buf,3);
ptr += 3;
} else {
int slen = strlen((char*)this->_serviceRecords[serviceRecord]->textContent);
*((uint16_t*)buf) = ethutil_htons(slen);
this->_udp->write((uint8_t*)buf,2);
ptr += 2;
this->_udp->write((uint8_t*)this->_serviceRecords[serviceRecord]->textContent,slen);
ptr += slen;
}
// PTR record (for the DNS-SD service in general)
this->_writeDNSName((const uint8_t*)DNS_SD_SERVICE, &ptr, buf,
sizeof(DNSHeader_t), 1);
buf[0] = 0x00;
buf[1] = 0x0c; // PTR record
buf[2] = 0x00; // no cache flush
buf[3] = 0x01; // class IN
// ttl
*((uint32_t*)&buf[4]) = ethutil_htonl(MDNS_RESPONSE_TTL);
// data length.
uint16_t dlen = strlen((char*)this->_serviceRecords[serviceRecord]->servName) + 2;
*((uint16_t*)&buf[8]) = ethutil_htons(dlen);
this->_udp->write((uint8_t*)buf, 10);
ptr += 10;
this->_writeServiceRecordName(serviceRecord, &ptr, buf, sizeof(DNSHeader_t), 1);
// PTR record (our service)
this->_writeServiceRecordPTR(serviceRecord, &ptr, buf, sizeof(DNSHeader_t),
MDNS_RESPONSE_TTL);
// finally, our IP address as additional record
this->_writeMyIPAnswerRecord(&ptr, buf, sizeof(DNSHeader_t));
break;
}
case MDNSPacketTypeServiceRecordRelease: {
// just send our service PTR with a TTL of zero
this->_writeServiceRecordPTR(serviceRecord, &ptr, buf, sizeof(DNSHeader_t), 0);
break;
}
#endif // defined(HAS_SERVICE_REGISTRATION) && HAS_SERVICE_REGISTRATION
#if defined(HAS_NAME_BROWSING) && HAS_NAME_BROWSING
case MDNSPacketTypeNameQuery:
case MDNSPacketTypeServiceQuery:
{
// construct a query for the currently set _resolveNames[0]
this->_writeDNSName(
(type == MDNSPacketTypeServiceQuery) ? this->_resolveNames[1] :
this->_resolveNames[0],
&ptr, buf, sizeof(DNSHeader_t), 1);
buf[0] = buf[2] = 0x0;
buf[1] = (type == MDNSPacketTypeServiceQuery) ? 0x0c : 0x01;
buf[3] = 0x1;
this->_udp->write((uint8_t*)buf, 4);
// ptr += sizeof(DNSHeader_t);
ptr += 4;
this->_resolveLastSendMillis[(type == MDNSPacketTypeServiceQuery) ? 1 : 0] = millis();
break;
}
#endif // defined(HAS_NAME_BROWSING) && HAS_NAME_BROWSING
case MDNSPacketTypeNoIPv6AddrAvailable: {
// since the WIZnet doesn't have IPv6, we will respond with a Not Found message
this->_writeDNSName(this->_name, &ptr, buf, sizeof(DNSHeader_t), 1);
buf[0] = buf[2] = 0x0;
buf[1] = 0x1c; // AAAA record
buf[3] = 0x01;
this->_udp->write((uint8_t*)buf, 4);
ptr += 4;
// send our IPv4 address record as additional record, in case the peer wants it.
this->_writeMyIPAnswerRecord(&ptr, buf, sizeof(DNSHeader_t));
break;
}
}
this->_udp->endPacket();
#if defined(_USE_MALLOC_)
errorReturn:
if (NULL != dnsHeader)
my_free(dnsHeader);
#endif
return statusCode;
}
// return value:
// A DNSError_t (DNSSuccess on success, something else otherwise)
// in "int" mode: positive on success, negative on error
MDNSError_t MDNS::_processMDNSQuery()
{
MDNSError_t statusCode = MDNSSuccess;
#if defined(_USE_MALLOC_)
DNSHeader_t* dnsHeader = NULL;
#else
DNSHeader_t dnsHeaderBuf;
DNSHeader_t* dnsHeader = &dnsHeaderBuf;
#endif
unsigned int i, j;
uint8_t* buf;
uint32_t xid = 0;
uint16_t udp_len, qCnt, aCnt, aaCnt, addCnt;
uint8_t recordsAskedFor[NumMDNSServiceRecords+2];
uint8_t recordsFound[2];
uint8_t wantsIPv6Addr = 0;
uint8_t * udpBuffer = NULL;
uintptr_t ptr;
memset(recordsAskedFor, 0, sizeof(uint8_t)*(NumMDNSServiceRecords+2));
memset(recordsFound, 0, sizeof(uint8_t)*2);
udp_len = this->_udp->parsePacket();
if (0 == udp_len) {
statusCode = MDNSTryLater;
goto errorReturn;
}
udpBuffer = (uint8_t*) my_malloc(udp_len); //allocate memory to hold _remaining UDP packet
if (NULL == udpBuffer) {
this->_udp->flush();
statusCode = MDNSOutOfMemory;
goto errorReturn;
}
this->_udp->read((uint8_t*)udpBuffer, udp_len);//read _remaining UDP packet from W5100/W5200 into memory
ptr = (uintptr_t)udpBuffer;
#if defined(_USE_MALLOC_)
dnsHeader = (DNSHeader_t*)my_malloc(sizeof(DNSHeader_t));
if (NULL == dnsHeader) {
statusCode = MDNSOutOfMemory;
goto errorReturn;
}
#endif
buf = (uint8_t*)dnsHeader;
memcpy((uint8_t*)buf, (uint16_t*)ptr ,sizeof(DNSHeader_t));
xid = ethutil_ntohs(dnsHeader->xid);
qCnt = ethutil_ntohs(dnsHeader->queryCount);
aCnt = ethutil_ntohs(dnsHeader->answerCount);
aaCnt = ethutil_ntohs(dnsHeader->authorityCount);
addCnt = ethutil_ntohs(dnsHeader->additionalCount);
if (0 == dnsHeader->queryResponse &&
DNSOpQuery == dnsHeader->opCode &&
MDNS_SERVER_PORT == this->_udp->remotePort())
{
// process an MDNS query
int offset = sizeof(DNSHeader_t);
uint8_t* buf = (uint8_t*)dnsHeader;
int rLen = 0, tLen = 0;
// read over the query section
for (i=0; i<qCnt; i++) {
// construct service name data structures for comparison
const uint8_t* servNames[NumMDNSServiceRecords+2];
int servLens[NumMDNSServiceRecords+2];
uint8_t servNamePos[NumMDNSServiceRecords+2];
uint8_t servMatches[NumMDNSServiceRecords+2];
// first entry is our own MDNS name, the rest are our services
servNames[0] = (const uint8_t*)this->_name;
servNamePos[0] = 0;
servLens[0] = strlen((char*)this->_name);
servMatches[0] = 1;
// second entry is our own the general DNS-SD service
servNames[1] = (const uint8_t*)DNS_SD_SERVICE;
servNamePos[1] = 0;
servLens[1] = strlen((char*)DNS_SD_SERVICE);
servMatches[1] = 1;
for (j=2; j<NumMDNSServiceRecords+2; j++)
if (NULL != this->_serviceRecords[j-2] && NULL != this->_serviceRecords[j-2]->servName) {
servNames[j] = this->_serviceRecords[j-2]->servName;
servLens[j] = strlen((char*)servNames[j]);
servMatches[j] = 1;
servNamePos[j] = 0;
} else {
servNames[j] = NULL;
servLens[j] = 0;
servMatches[j] = 0;
servNamePos[j] = 0;
}
tLen = 0;
do {
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,1);
offset += 1;
rLen = buf[0];
tLen += 1;
if (rLen > 128) {// handle DNS name compression, kinda, sorta
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,1);
offset += 1;
for (j=0; j<NumMDNSServiceRecords+2; j++) {
if (servNamePos[j] && servNamePos[j] != buf[0]) {
servMatches[j] = 0;
}
}
tLen += 1;
} else if (rLen > 0) {
int tr = rLen, ir;
while (tr > 0) {
ir = (tr > (int)sizeof(DNSHeader_t)) ? sizeof(DNSHeader_t) : tr;
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,ir);
offset += ir;
tr -= ir;
for (j=0; j<NumMDNSServiceRecords+2; j++) {
if (!recordsAskedFor[j] && servMatches[j])
servMatches[j] &= this->_matchStringPart(&servNames[j], &servLens[j], buf,
ir);
}
}
tLen += rLen;
}
} while (rLen > 0 && rLen <= 128);
// if this matched a name of ours (and there are no characters left), then
// check whether this is an A record query (for our own name) or a PTR record query
// (for one of our services).
// if so, we'll note to send a record
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,4);
offset += 4;
for (j=0; j<NumMDNSServiceRecords+2; j++) {
if (!recordsAskedFor[j] && servNames[j] && servMatches[j] && 0 == servLens[j]) {
if (0 == servNamePos[j])
servNamePos[j] = offset - 4 - tLen;
if (buf[0] == 0 && buf[3] == 0x01 &&
(buf[2] == 0x00 || buf[2] == 0x80)) {
if ((0 == j && 0x01 == buf[1]) || (0 < j && (0x0c == buf[1] || 0x10 == buf[1] || 0x21 == buf[1])))
recordsAskedFor[j] = 1;
else if (0 == j && 0x1c == buf[1])
wantsIPv6Addr = 1;
}
}
}
}
}
#if (defined(HAS_SERVICE_REGISTRATION) && HAS_SERVICE_REGISTRATION) || (defined(HAS_NAME_BROWSING) && HAS_NAME_BROWSING)
else if (1 == dnsHeader->queryResponse &&
DNSOpQuery == dnsHeader->opCode &&
MDNS_SERVER_PORT == this->_udp->remotePort() &&
(NULL != this->_resolveNames[0] || NULL != this->_resolveNames[1]))
{
int offset = sizeof(DNSHeader_t);
uint8_t* buf = (uint8_t*)dnsHeader;
int rLen = 0, tLen = 0;
uint8_t* ptrNames[MDNS_MAX_SERVICES_PER_PACKET];
uint16_t ptrOffsets[MDNS_MAX_SERVICES_PER_PACKET];
uint16_t ptrPorts[MDNS_MAX_SERVICES_PER_PACKET];
uint8_t ptrIPs[MDNS_MAX_SERVICES_PER_PACKET];
uint8_t servIPs[MDNS_MAX_SERVICES_PER_PACKET][5];
uint8_t* servTxt[MDNS_MAX_SERVICES_PER_PACKET];
memset(servIPs, 0, sizeof(uint8_t)*MDNS_MAX_SERVICES_PER_PACKET*5);
memset(servTxt, 0, sizeof(uint8_t*)*MDNS_MAX_SERVICES_PER_PACKET);
const uint8_t* ptrNamesCmp[MDNS_MAX_SERVICES_PER_PACKET];
int ptrLensCmp[MDNS_MAX_SERVICES_PER_PACKET];
uint8_t ptrNamesMatches[MDNS_MAX_SERVICES_PER_PACKET];
uint8_t checkAARecords = 0;
memset(ptrNames, 0, sizeof(uint8_t*)*MDNS_MAX_SERVICES_PER_PACKET);
const uint8_t* servNames[2];
uint8_t servNamePos[2];
int servLens[2];
uint8_t servMatches[2];
uint8_t firstNamePtrByte = 0;
uint8_t partMatched[2];
uint8_t lastWasCompressed[2];
uint8_t servWasCompressed[2];
servNamePos[0] = servNamePos[1] = 0;
for (i=0; i<(unsigned int)(qCnt+aCnt+aaCnt+addCnt); i++) {
for (j=0; j<2; j++) {
if (NULL != this->_resolveNames[j]) {
servNames[j] = this->_resolveNames[j];
servLens[j] = strlen((const char*)this->_resolveNames[j]);
servMatches[j] = 1;
} else {
servNames[j] = NULL;
servLens[j] = servMatches[j] = 0;
}
}
for (j=0; j<MDNS_MAX_SERVICES_PER_PACKET; j++) {
if (NULL != ptrNames[j]) {
ptrNamesCmp[j] = ptrNames[j];
ptrLensCmp[j] = strlen((const char*)ptrNames[j]);
ptrNamesMatches[j] = 1;
}
}
partMatched[0] = partMatched[1] = 0;
lastWasCompressed[0] = lastWasCompressed[1] = 0;
servWasCompressed[0] = servWasCompressed[1] = 0;
firstNamePtrByte = 0;
tLen = 0;
do {
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,1);
offset += 1;
rLen = buf[0];
tLen += 1;
if (rLen > 128) { // handle DNS name compression, kinda, sorta...
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,1);
offset += 1;
for (j=0; j<2; j++) {
if (servNamePos[j] && servNamePos[j] != buf[0])
servMatches[j] = 0;
else
servWasCompressed[j] = 1;
lastWasCompressed[j] = 1;
}
tLen += 1;
if (0 == firstNamePtrByte)
firstNamePtrByte = buf[0];
} else if (rLen > 0) {
if (i < qCnt)
offset += rLen;
else {
int tr = rLen, ir;
if (0 == firstNamePtrByte)
firstNamePtrByte = offset-1; // -1, since we already read length (1 byte)
while (tr > 0) {
ir = (tr > (int)sizeof(DNSHeader_t)) ? sizeof(DNSHeader_t) : tr;
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,ir);
offset += ir;
tr -= ir;
for (j=0; j<2; j++) {
if (!recordsFound[j] && servMatches[j] && servNames[j])
servMatches[j] &= this->_matchStringPart(&servNames[j], &servLens[j],
buf, ir);
if (!partMatched[j])
partMatched[j] = servMatches[j];
lastWasCompressed[j] = 0;
}
for (j=0; j<MDNS_MAX_SERVICES_PER_PACKET; j++) {
if (NULL != ptrNames[j] && ptrNamesMatches[j]) {
// only compare the part we have. this is incorrect, but good enough,
// since actual mDNS implementations won't go here anyways, as they
// should use name compression. This is just so that multiple Arduinos
// running this mDNSResponder code should be able to find each other's
// services.
if (ptrLensCmp[j] >= ir)
ptrNamesMatches[j] &= this->_matchStringPart(&ptrNamesCmp[j],
&ptrLensCmp[j], buf, ir);
}
}
}
tLen += rLen;
}
}
} while (rLen > 0 && rLen <= 128);
// if this matched a name of ours (and there are no characters left), then
// check whether this is an A record query (for our own name) or a PTR record query
// (for one of our services).
// if so, we'll note to send a record
if (i < qCnt)
offset += 4;
else if (i >= qCnt) {
if (i >= qCnt + aCnt && !checkAARecords)
break;
uint8_t packetHandled = 0;
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,4);
offset += 4;
if (i < qCnt+aCnt) {
for (j=0; j<2; j++) {
if (0 == servNamePos[j])
servNamePos[j] = offset - 4 - tLen;
if (servNames[j] &&
((servMatches[j] && 0 == servLens[j]) ||
(partMatched[j] && lastWasCompressed[j]) ||
(servWasCompressed[j] && servMatches[j]))) { // somewhat handle compression by guessing
if (buf[0] == 0 && buf[1] == ((0 == j) ? 0x01 : 0x0c) &&
(buf[2] == 0x00 || buf[2] == 0x80) && buf[3] == 0x01) {
recordsFound[j] = 1;
// this is an A or PTR type response. Parse it as such.
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,6);
offset += 6;
//uint32_t ttl = ethutil_ntohl(*(uint32_t*)buf);
uint16_t dataLen = ethutil_ntohs(*(uint16_t*)&buf[4]);
if (0 == j && 4 == dataLen) {
// ok, this is the IP address. report it via callback.
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,4);
this->_finishedResolvingName((char*)this->_resolveNames[0],
(const byte*)buf);
} else if (1 == j) {
uint8_t k;
for (k=0; k<MDNS_MAX_SERVICES_PER_PACKET; k++)
if (NULL == ptrNames[k])
break;
if (k < MDNS_MAX_SERVICES_PER_PACKET) {
int l = dataLen - 2; // -2: data compression of service postfix
uint8_t* ptrName = (uint8_t*)my_malloc(l);
if (ptrName) {
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,1);
memcpy((uint8_t*)ptrName, (uint16_t*)(ptr+offset+1) ,l-1);
if (buf[0] < l-1)
ptrName[buf[0]] = '\0'; // this catches uncompressed names
else
ptrName[l-1] = '\0';
ptrNames[k] = ptrName;
ptrOffsets[k] = (uint16_t)(offset);
checkAARecords = 1;
}
}
}
offset += dataLen;
packetHandled = 1;
}
}
}
} else if (i >= (unsigned int)(qCnt+aCnt+aaCnt)) {
// check whether we find a service description
if (buf[1] == 0x21) {
for (j=0; j<MDNS_MAX_SERVICES_PER_PACKET; j++) {
if (ptrNames[j] &&
((firstNamePtrByte && firstNamePtrByte == ptrOffsets[j]) ||
(0 == ptrLensCmp[j] && ptrNamesMatches[j]))) {
// we have found the matching SRV location packet to a previous SRV domain
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,6);
offset += 6;
//uint32_t ttl = ethutil_ntohl(*(uint32_t*)buf);
uint16_t dataLen = ethutil_ntohs(*(uint16_t*)&buf[4]);
if (dataLen >= 8) {
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,8);
ptrPorts[j] = ethutil_ntohs(*(uint16_t*)&buf[4]);
if (buf[6] > 128) { // target is a compressed name
ptrIPs[j] = buf[7];
} else { // target is uncompressed
ptrIPs[j] = offset+6;
}
}
offset += dataLen;
packetHandled = 1;
break;
}
}
} else if (buf[1] == 0x10) { // txt record
for (j=0; j<MDNS_MAX_SERVICES_PER_PACKET; j++) {
if (ptrNames[j] &&
((firstNamePtrByte && firstNamePtrByte == ptrOffsets[j]) ||
(0 == ptrLensCmp[j] && ptrNamesMatches[j]))) {
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,6);
offset += 6;
//uint32_t ttl = ethutil_ntohl(*(uint32_t*)buf);
uint16_t dataLen = ethutil_ntohs(*(uint16_t*)&buf[4]);
// if there's a content to this txt record, save it for delivery
if (dataLen > 1 && NULL == servTxt[j]) {
servTxt[j] = (uint8_t*)my_malloc(dataLen+1);
if (NULL != servTxt[j]) {
memcpy((uint8_t*)servTxt[j], (uint16_t*)(ptr+offset) ,dataLen);
// zero-terminate
servTxt[j][dataLen] = '\0';
}
}
offset += dataLen;
packetHandled = 1;
break;
}
}
} else if (buf[1] == 0x01) { // A record (IPv4 address)
for (j=0; j<MDNS_MAX_SERVICES_PER_PACKET; j++) {
if (0 == servIPs[j][0]) {
servIPs[j][0] = firstNamePtrByte ? firstNamePtrByte : 255;
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset) ,6);
offset += 6;
uint16_t dataLen = ethutil_ntohs(*(uint16_t*)&buf[4]);
if (4 == dataLen) {
memcpy((uint8_t*)&servIPs[j][1], (uint16_t*)(ptr+offset) ,4);
}
offset += dataLen;
packetHandled = 1;
break;
}
}
}
}
// eat the answer
if (!packetHandled) {
offset += 4; // ttl
memcpy((uint8_t*)buf, (uint16_t*)(ptr+offset), 2);
offset += 2 + ethutil_ntohs(*(uint16_t*)buf); // skip over content
}
}
}
// deliver the services discovered in this packet
if (NULL != this->_resolveNames[1]) {
char* typeName = (char*)this->_resolveNames[1];
char* p = (char*)this->_resolveNames[1];
while(*p && *p != '.')
p++;
*p = '\0';
for (i=0; i<MDNS_MAX_SERVICES_PER_PACKET; i++)
if (ptrNames[i]) {
const uint8_t* ipAddr = NULL;
const uint8_t* fallbackIpAddr = NULL;
for (j=0; j<MDNS_MAX_SERVICES_PER_PACKET; j++) {
if (servIPs[j][0] == ptrIPs[i] || servIPs[j][0] == 255) {
// the || part is such a hack, but it will work as long as there's only
// one A record per mDNS packet. fucking DNS name compression.
ipAddr = &servIPs[j][1];
break;
} else if (NULL == fallbackIpAddr && 0 != servIPs[j][0])
fallbackIpAddr = &servIPs[j][1];
}
// if we can't find a matching IP, we try to use the first one we found.
if (NULL == ipAddr) ipAddr = fallbackIpAddr;
if (ipAddr && this->_serviceFoundCallback) {
this->_serviceFoundCallback(typeName,
this->_resolveServiceProto,
(const char*)ptrNames[i],
IPAddress((const byte*)ipAddr),
(unsigned short)ptrPorts[i],
(const char*)servTxt[i]);