void dnsProcessResponse(NetInterface *interface, const IpPseudoHeader *pseudoHeader,
const UdpHeader *udpHeader, const ChunkedBuffer *buffer, size_t offset, void *params)
{
uint_t i;
uint_t j;
size_t n;
size_t pos;
size_t length;
DnsHeader *message;
DnsQuestion *question;
DnsResourceRecord *resourceRecord;
DnsCacheEntry *entry;
//Retrieve the length of the DNS message
length = chunkedBufferGetLength(buffer) - offset;
//Ensure the DNS message is valid
if(length < sizeof(DnsHeader))
return;
if(length > DNS_MESSAGE_MAX_SIZE)
return;
//Point to the DNS message header
message = chunkedBufferAt(buffer, offset);
//Sanity check
if(!message) return;
//Debug message
TRACE_INFO("DNS message received (%" PRIuSIZE " bytes)...\r\n", length);
//Dump message
dnsDumpMessage(message, length);
//Acquire exclusive access to the DNS cache
osMutexAcquire(dnsCacheMutex);
//Loop through DNS cache entries
for(i = 0; i < DNS_CACHE_SIZE; i++)
{
//Point to the current entry
entry = &dnsCache[i];
//DNS name resolution in progress?
if(entry->state == DNS_STATE_IN_PROGRESS &&
entry->protocol == HOST_NAME_RESOLVER_DNS)
{
//Check destination port number
if(entry->port == ntohs(udpHeader->destPort))
{
//Compare identifier against expected one
if(ntohs(message->id) != entry->id)
break;
//Check message type
if(!message->qr)
break;
//The DNS message shall contain one question
if(ntohs(message->qdcount) != 1)
break;
//Point to the first question
pos = sizeof(DnsHeader);
//Parse domain name
n = dnsParseName(message, length, pos, NULL, 0);
//Invalid name?
if(!n)
break;
//Malformed mDNS message?
if((n + sizeof(DnsQuestion)) > length)
break;
//Compare domain name
if(!dnsCompareName(message, length, pos, entry->name, 0))
break;
//Point to the corresponding entry
question = DNS_GET_QUESTION(message, n);
//Check the class of the query
if(ntohs(question->qclass) != DNS_RR_CLASS_IN)
break;
//Check the type of the query
if(entry->type == HOST_TYPE_IPV4 && ntohs(question->qtype) != DNS_RR_TYPE_A)
break;
if(entry->type == HOST_TYPE_IPV6 && ntohs(question->qtype) != DNS_RR_TYPE_AAAA)
break;
//Make sure recursion is available
if(!message->ra)
{
//The entry should be deleted since name resolution has failed
dnsDeleteEntry(entry);
//Exit immediately
break;
}
//Check return code
if(message->rcode != DNS_RCODE_NO_ERROR)
{
//The entry should be deleted since name resolution has failed
dnsDeleteEntry(entry);
//Exit immediately
break;
}
//Point to the first answer
pos = n + sizeof(DnsQuestion);
//Parse answer resource records
for(j = 0; j < ntohs(message->ancount); j++)
{
//Parse domain name
pos = dnsParseName(message, length, pos, NULL, 0);
//Invalid name?
if(!pos) break;
//Point to the associated resource record
resourceRecord = DNS_GET_RESOURCE_RECORD(message, pos);
//Point to the resource data
pos += sizeof(DnsResourceRecord);
//Make sure the resource record is valid
if(pos >= length)
break;
if((pos + ntohs(resourceRecord->rdlength)) > length)
break;
#if (IPV4_SUPPORT == ENABLED)
//IPv4 address expected?
if(entry->type == HOST_TYPE_IPV4)
{
//A resource record found?
if(ntohs(resourceRecord->rtype) == DNS_RR_TYPE_A)
{
//Verify the length of the data field
if(ntohs(resourceRecord->rdlength) == sizeof(Ipv4Addr))
{
//Copy the IPv4 address
entry->ipAddr.length = sizeof(Ipv4Addr);
ipv4CopyAddr(&entry->ipAddr.ipv4Addr, resourceRecord->rdata);
//Save current time
entry->timestamp = osGetTickCount();
//Save TTL value
entry->timeout = ntohl(resourceRecord->ttl) * 1000;
//Limit the lifetime of the DNS cache entries
entry->timeout = min(entry->timeout, DNS_MAX_LIFETIME);
//Unregister UDP callback function
udpDetachRxCallback(interface, entry->port);
//Host name successfully resolved
entry->state = DNS_STATE_RESOLVED;
//Exit immediately
break;
}
}
}
#endif
#if (IPV6_SUPPORT == ENABLED)
//IPv6 address expected?
if(entry->type == HOST_TYPE_IPV6)
{
//AAAA resource record found?
if(ntohs(resourceRecord->rtype) == DNS_RR_TYPE_AAAA)
{
//Verify the length of the data field
if(ntohs(resourceRecord->rdlength) == sizeof(Ipv6Addr))
{
//Copy the IPv6 address
entry->ipAddr.length = sizeof(Ipv6Addr);
ipv6CopyAddr(&entry->ipAddr.ipv6Addr, resourceRecord->rdata);
//Save current time
entry->timestamp = osGetTickCount();
//Save TTL value
entry->timeout = ntohl(resourceRecord->ttl) * 1000;
//Limit the lifetime of the DNS cache entries
entry->timeout = min(entry->timeout, DNS_MAX_LIFETIME);
//Unregister UDP callback function
udpDetachRxCallback(interface, entry->port);
//Host name successfully resolved
entry->state = DNS_STATE_RESOLVED;
//Exit immediately
break;
}
}
}
#endif
//Point to the next resource record
pos += ntohs(resourceRecord->rdlength);
}
//We are done
break;
}
}
}
//Release exclusive access to the DNS cache
osMutexRelease(dnsCacheMutex);
}
void mdnsProcessQuery(NetInterface *interface, const IpPseudoHeader *pseudoHeader,
const UdpHeader *udpHeader, const DnsHeader *query, size_t queryLen)
{
error_t error;
uint_t i;
size_t pos;
size_t offset;
size_t responseLen;
DnsHeader *response;
NetBuffer *buffer;
//Check the state of the mDNS responder
if(interface->mdnsContext.state != MDNS_STATE_DONE)
return;
//Initialize error code
error = NO_ERROR;
//This buffer will hold the mDNS response, if any
buffer = NULL;
//Point to the first question
pos = sizeof(DnsHeader);
//Parse question section
for(i = 0; i < ntohs(query->qdcount); i++)
{
size_t n;
uint16_t qclass;
uint16_t qtype;
DnsQuestion *question;
//Parse domain name
n = dnsParseName(query, queryLen, pos, NULL, 0);
//Invalid name?
if(!n)
break;
//Malformed mDNS message?
if((n + sizeof(DnsQuestion)) > queryLen)
break;
//Point to the corresponding entry
question = DNS_GET_QUESTION(query, n);
//Convert the query class to host byte order
qclass = ntohs(question->qclass);
//Discard QU flag
qclass &= ~MDNS_QCLASS_QU;
//Convert the query type to host byte order
qtype = ntohs(question->qtype);
//Check the class of the query
if(qclass == DNS_RR_CLASS_IN || qclass == DNS_RR_CLASS_ANY)
{
#if (DNS_SD_SUPPORT == ENABLED)
//PTR query?
if(qtype == DNS_RR_TYPE_PTR || qtype == DNS_RR_TYPE_ANY)
{
uint_t j;
//Service type enumeration meta-query received?
if(mdnsCompareName(query, queryLen, pos, "", "_services._dns-sd._udp", ".local", 0))
{
//Any registered services?
if(interface->numServices > 0 && interface->instanceName != NULL)
{
//Create a mDNS response message only if necessary
if(!buffer)
{
//Allocate the mDNS response message
buffer = mdnsCreateResponse(query->id, &offset, &response, &responseLen);
//Failed to allocate memory?
if(!buffer) break;
}
//Loop through registered services
for(j = 0; j < interface->numServices; j++)
{
//Format PTR resource record
error = dnsSdAddPtrResourceRecord(interface,
&interface->services[j], TRUE, response, &responseLen);
//Any error to report?
if(error) break;
}
//Propagate exception if necessary...
if(error) break;
}
}
else
{
//Loop through registered services
for(j = 0; j < interface->numServices; j++)
{
//Compare service name
if(mdnsCompareName(query, queryLen, pos, "",
interface->services[j].name, ".local", 0))
{
//The current service name matches a registered service
break;
}
}
//Any matching service name?
if(j < interface->numServices && interface->instanceName != NULL)
{
//Create a mDNS response message only if necessary
if(!buffer)
{
//Allocate the mDNS response message
buffer = mdnsCreateResponse(query->id, &offset, &response, &responseLen);
//Failed to allocate memory?
if(!buffer) break;
}
//Format PTR resource record
error = dnsSdAddPtrResourceRecord(interface,
&interface->services[j], FALSE, response, &responseLen);
//Any error to report?
if(error) break;
//Format TXT resource record
error = dnsSdAddTxtResourceRecord(interface,
&interface->services[j], response, &responseLen);
//Any error to report?
if(error) break;
//Format SRV resource record
error = dnsSdAddSrvResourceRecord(interface,
&interface->services[j], response, &responseLen);
//Any error to report?
if(error) break;
//Format A resource record
error = mdnsAddIpv4ResourceRecord(interface,
response, &responseLen, FALSE);
//Any error to report?
if(error) break;
//Format AAAA resource record
error = mdnsAddIpv6ResourceRecord(interface,
response, &responseLen, FALSE);
//Any error to report?
if(error) break;
}
}
}
//SRV or TXT query?
else if(qtype == DNS_RR_TYPE_SRV || qtype == DNS_RR_TYPE_TXT)
{
uint_t j;
//Loop through registered services
for(j = 0; j < interface->numServices; j++)
{
//Compare service name
if(mdnsCompareName(query, queryLen, pos, interface->instanceName,
interface->services[j].name, ".local", 0))
{
//The current service name matches a registered service
break;
}
}
//Any matching service name?
if(j < interface->numServices && interface->instanceName != NULL)
{
//Create a mDNS response message only if necessary
if(!buffer)
{
//Allocate the mDNS response message
buffer = mdnsCreateResponse(query->id, &offset, &response, &responseLen);
//Failed to allocate memory?
if(!buffer) break;
}
//Check query type?
if(qtype == DNS_RR_TYPE_TXT)
{
//Format TXT resource record
error = dnsSdAddTxtResourceRecord(interface,
&interface->services[j], response, &responseLen);
//Any error to report?
if(error) break;
}
else if(qtype == DNS_RR_TYPE_SRV)
{
//Format SRV resource record
error = dnsSdAddSrvResourceRecord(interface,
&interface->services[j], response, &responseLen);
//Any error to report?
if(error) break;
//Format A resource record
error = mdnsAddIpv4ResourceRecord(interface,
response, &responseLen, FALSE);
//Any error to report?
if(error) break;
//Format AAAA resource record
error = mdnsAddIpv6ResourceRecord(interface,
response, &responseLen, FALSE);
//Any error to report?
if(error) break;
}
}
}
#endif
#if (IPV4_SUPPORT == ENABLED)
//A query?
#if (DNS_SD_SUPPORT == ENABLED)
if(qtype == DNS_RR_TYPE_A)
#else
if(qtype == DNS_RR_TYPE_A || qtype == DNS_RR_TYPE_ANY)
#endif
{
//Compare domain name
if(mdnsCompareName(query, queryLen, pos, interface->hostname, "", ".local", 0))
{
//Create a mDNS response message only if necessary
if(!buffer)
{
//Allocate the mDNS response message
buffer = mdnsCreateResponse(query->id, &offset, &response, &responseLen);
//Failed to allocate memory?
if(!buffer) break;
}
//Format A resource record
error = mdnsAddIpv4ResourceRecord(interface, response, &responseLen, FALSE);
//Any error to report?
if(error) break;
}
}
#endif
#if (IPV6_SUPPORT == ENABLED)
//AAAA query?
#if (DNS_SD_SUPPORT == ENABLED)
if(qtype == DNS_RR_TYPE_AAAA)
#else
if(qtype == DNS_RR_TYPE_AAAA || qtype == DNS_RR_TYPE_ANY)
#endif
{
//Compare domain name
if(mdnsCompareName(query, queryLen, pos, interface->hostname, "", ".local", 0))
{
//Create a mDNS response message only if necessary
if(!buffer)
{
//Allocate the mDNS response message
buffer = mdnsCreateResponse(query->id, &offset, &response, &responseLen);
//Failed to allocate memory?
if(!buffer) break;
}
//Format AAAA resource record
error = mdnsAddIpv6ResourceRecord(interface, response, &responseLen, FALSE);
//Any error to report?
if(error) break;
}
}
#endif
}
//Point to the next question
pos = n + sizeof(DnsQuestion);
}
//Any response to send?
if(buffer != NULL)
{
//Check status code
if(!error)
{
//Send mDNS response message
mdnsSendResponse(interface, pseudoHeader, udpHeader,
buffer, offset, responseLen);
}
//Free previously allocated memory
netBufferFree(buffer);
}
}
