/*********************************************************************
* Function: void DNSServerTask(void)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: None
*
* Overview: Sends dummy responses that point to ourself for DNS requests
*
* Note: None
********************************************************************/
void DNSServerTask(void)
{
static UDP_SOCKET MySocket = INVALID_UDP_SOCKET;
struct
{
WORD wTransactionID;
WORD wFlags;
WORD wQuestions;
WORD wAnswerRRs;
WORD wAuthorityRRs;
WORD wAdditionalRRs;
} DNSHeader;
// Create a socket to listen on if this is the first time calling this function
if(MySocket == INVALID_UDP_SOCKET)
{
//MySocket = UDPOpen(DNS_PORT, NULL, 0);
MySocket = UDPOpenEx(0,UDP_OPEN_SERVER,DNS_PORT,0);
return;
}
// See if a DNS query packet has arrived
if(UDPIsGetReady(MySocket) < sizeof(DNSHeader))
return;
// Read DNS header
UDPGetArray((BYTE*)&DNSHeader, sizeof(DNSHeader));
// Ignore this packet if it isn't a query
if((DNSHeader.wFlags & 0x8000) == 0x8000u)
return;
// Ignore this packet if there are no questions in it
if(DNSHeader.wQuestions == 0u)
return;
// Block until we can transmit a DNS response packet
while(!UDPIsPutReady(MySocket));
// Write DNS response packet
UDPPutArray((BYTE*)&DNSHeader.wTransactionID, 2); // 2 byte Transaction ID
if(DNSHeader.wFlags & 0x0100)
UDPPut(0x81); // Message is a response with recursion desired
else
UDPPut(0x80); // Message is a response without recursion desired flag set
UDPPut(0x80); // Recursion available
UDPPut(0x00); // 0x0000 Questions
UDPPut(0x00);
UDPPut(0x00); // 0x0001 Answers RRs
UDPPut(0x01);
UDPPut(0x00); // 0x0000 Authority RRs
UDPPut(0x00);
UDPPut(0x00); // 0x0000 Additional RRs
UDPPut(0x00);
DNSCopyRXNameToTX(); // Copy hostname of first question over to TX packet
UDPPut(0x00); // Type A Host address
UDPPut(0x01);
UDPPut(0x00); // Class INternet
UDPPut(0x01);
UDPPut(0x00); // Time to Live 10 seconds
UDPPut(0x00);
UDPPut(0x00);
UDPPut(0x0A);
UDPPut(0x00); // Data Length 4 bytes
UDPPut(0x04);
UDPPutArray((BYTE*)&AppConfig.MyIPAddr.Val, 4); // Our IP address
#warning tim had added extra code here
UDPFlush();
}
/*********************************************************************
* Function: void DNSServerTask(NET_CONFIG* pNet)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: None
*
* Overview: Sends dummy responses that point to ourself for DNS requests
*
* Note: None
********************************************************************/
void DNSServerTask(NET_CONFIG* pNet)
{
static UDP_SOCKET MySocket = INVALID_UDP_SOCKET;
static struct
{
uint16_t wTransactionID;
uint16_t wFlags;
uint16_t wQuestions;
uint16_t wAnswerRRs;
uint16_t wAuthorityRRs;
uint16_t wAdditionalRRs;
} DNSHeader;
switch(dnssState)
{
case DNSS_STATE_START:
// Create a socket to listen on if this is the first time calling this function
if(MySocket == INVALID_UDP_SOCKET)
{
MySocket = UDPOpen(0,UDP_OPEN_SERVER,DNS_PORT,0);
if(MySocket == INVALID_UDP_SOCKET)
break;
}
UDPSocketSetNet(MySocket, pNet);
dnssState = DNSS_STATE_WAIT_REQUEST;
break;
case DNSS_STATE_WAIT_REQUEST:
// See if a DNS query packet has arrived
if(UDPIsGetReady(MySocket) < sizeof(DNSHeader))
break;
// Read DNS header
UDPGetArray(MySocket, (uint8_t*)&DNSHeader, sizeof(DNSHeader));
// Ignore this packet if it isn't a query
if((DNSHeader.wFlags & 0x8000) == 0x8000u)
break;
// Ignore this packet if there are no questions in it
if(DNSHeader.wQuestions == 0u)
break;
dnssState = DNSS_STATE_PUT_REQUEST;
break;
case DNSS_STATE_PUT_REQUEST:
// check that we can transmit a DNS response packet
if(!UDPIsPutReady(MySocket))
{
break;
}
// Write DNS response packet
UDPPutArray(MySocket, (uint8_t*)&DNSHeader.wTransactionID, 2); // 2 byte Transaction ID
if(DNSHeader.wFlags & 0x0100)
UDPPut(MySocket, 0x81); // Message is a response with recursion desired
else
UDPPut(MySocket, 0x80); // Message is a response without recursion desired flag set
UDPPut(MySocket, 0x80); // Recursion available
UDPPut(MySocket, 0x00); // 0x0000 Questions
UDPPut(MySocket, 0x00);
UDPPut(MySocket, 0x00); // 0x0001 Answers RRs
UDPPut(MySocket, 0x01);
UDPPut(MySocket, 0x00); // 0x0000 Authority RRs
UDPPut(MySocket, 0x00);
UDPPut(MySocket, 0x00); // 0x0000 Additional RRs
UDPPut(MySocket, 0x00);
DNSCopyRXNameToTX(MySocket, pNet); // Copy hostname of first question over to TX packet
UDPPut(MySocket, 0x00); // Type A Host address
UDPPut(MySocket, 0x01);
UDPPut(MySocket, 0x00); // Class INternet
UDPPut(MySocket, 0x01);
UDPPut(MySocket, 0x00); // Time to Live 10 seconds
UDPPut(MySocket, 0x00);
UDPPut(MySocket, 0x00);
UDPPut(MySocket, 0x0A);
UDPPut(MySocket, 0x00); // Data Length 4 bytes
UDPPut(MySocket, 0x04);
UDPPutArray(MySocket, (uint8_t*)&pNet->MyIPAddr.Val, 4); // Our IP address
UDPFlush(MySocket);
dnssState = DNSS_STATE_DONE;
break;
case DNSS_STATE_DONE:
break;
}
}
