コード例 #1
0
error_t nbnsSendQuery(DnsCacheEntry *entry)
{
   error_t error;
   size_t length;
   size_t offset;
   NetBuffer *buffer;
   NbnsHeader *message;
   DnsQuestion *dnsQuestion;
   IpAddr destIpAddr;

   //Allocate a memory buffer to hold the NBNS query message
   buffer = udpAllocBuffer(DNS_MESSAGE_MAX_SIZE, &offset);
   //Failed to allocate buffer?
   if(!buffer) return ERROR_OUT_OF_MEMORY;

   //Point to the NBNS header
   message = netBufferAt(buffer, offset);

   //Format NBNS query message
   message->id = htons(entry->id);
   message->qr = 0;
   message->opcode = DNS_OPCODE_QUERY;
   message->aa = 0;
   message->tc = 0;
   message->rd = 0;
   message->ra = 0;
   message->z = 0;
   message->b = 1;
   message->rcode = DNS_RCODE_NO_ERROR;

   //The NBNS query contains one question
   message->qdcount = HTONS(1);
   message->ancount = 0;
   message->nscount = 0;
   message->arcount = 0;

   //Length of the NBNS query message
   length = sizeof(DnsHeader);

   //Encode the NetBIOS name
   length += nbnsEncodeName(entry->name, message->questions);

   //Point to the corresponding question structure
   dnsQuestion = DNS_GET_QUESTION(message, length);
   //Fill in question structure
   dnsQuestion->qtype = HTONS(DNS_RR_TYPE_NB);
   dnsQuestion->qclass = HTONS(DNS_RR_CLASS_IN);

   //Update the length of the NBNS query message
   length += sizeof(DnsQuestion);

   //Adjust the length of the multi-part buffer
   netBufferSetLength(buffer, offset + length);

   //Debug message
   TRACE_INFO("Sending NBNS message (%" PRIuSIZE " bytes)...\r\n", length);
   //Dump message
   dnsDumpMessage((DnsHeader *) message, length);

   //The destination address is the broadcast address
   destIpAddr.length = sizeof(Ipv4Addr);
   ipv4GetBroadcastAddr(entry->interface, &destIpAddr.ipv4Addr);

   //A request packet is always sent to the well known port 137
   error = udpSendDatagramEx(entry->interface, NBNS_PORT,
      &destIpAddr, NBNS_PORT, buffer, offset, IPV4_DEFAULT_TTL);

   //Free previously allocated memory
   netBufferFree(buffer);
   //Return status code
   return error;
}
コード例 #2
0
ファイル: nbns_responder.c プロジェクト: nandojve/embedded
error_t nbnsSendResponse(NetInterface *interface,
   const IpAddr *destIpAddr, uint16_t destPort, uint16_t id)
{
   error_t error;
   size_t length;
   size_t offset;
   ChunkedBuffer *buffer;
   NbnsHeader *message;
   NbnsAddrEntry *addrEntry;
   DnsResourceRecord *resourceRecord;

   //Allocate a memory buffer to hold the NBNS response message
   buffer = udpAllocBuffer(DNS_MESSAGE_MAX_SIZE, &offset);
   //Failed to allocate buffer?
   if(!buffer) return ERROR_OUT_OF_MEMORY;

   //Point to the NBNS header
   message = chunkedBufferAt(buffer, offset);

   //Take the identifier from the query message
   message->id = id;

   //Format NBNS response header
   message->qr = 1;
   message->opcode = DNS_OPCODE_QUERY;
   message->aa = 1;
   message->tc = 0;
   message->rd = 1;
   message->ra = 1;
   message->z = 0;
   message->b = 0;
   message->rcode = DNS_RCODE_NO_ERROR;

   //The NBNS response contains 1 answer resource record
   message->qdcount = 0;
   message->ancount = HTONS(1);
   message->nscount = 0;
   message->arcount = 0;

   //NBNS response message length
   length = sizeof(DnsHeader);

   //Encode the host name using the NBNS name notation
   length += nbnsEncodeName(interface->hostname, (uint8_t *) message + length);

   //Point to the corresponding resource record
   resourceRecord = DNS_GET_RESOURCE_RECORD(message, length);
   //Fill in resource record
   resourceRecord->rtype = HTONS(DNS_RR_TYPE_NB);
   resourceRecord->rclass = HTONS(DNS_RR_CLASS_IN);
   resourceRecord->ttl = HTONL(NBNS_DEFAULT_RESOURCE_RECORD_TTL);
   resourceRecord->rdlength = HTONS(sizeof(NbnsAddrEntry));

   //Point to the address entry array
   addrEntry = (NbnsAddrEntry *) resourceRecord->rdata;
   //Fill in address entry
   addrEntry->flags = HTONS(NBNS_G_UNIQUE | NBNS_ONT_BNODE);
   addrEntry->addr = interface->ipv4Config.addr;

   //Update the length of the NBNS response message
   length += sizeof(DnsResourceRecord) + sizeof(NbnsAddrEntry);

   //Adjust the length of the multi-part buffer
   chunkedBufferSetLength(buffer, offset + length);

   //Debug message
   TRACE_INFO("Sending NBNS message (%" PRIuSIZE " bytes)...\r\n", length);
   //Dump message
   dnsDumpMessage((DnsHeader *) message, length);

   //A response packet is always sent to the source UDP port and
   //source IP address of the request packet
   error = udpSendDatagramEx(interface, NBNS_PORT, destIpAddr,
      destPort, buffer, offset, IPV4_DEFAULT_TTL);

   //Free previously allocated memory
   chunkedBufferFree(buffer);
   //Return status code
   return error;
}