/** Decodes an ARP header and prints its contents to through the USART in a human readable format.
*
* \param[in] InDataStart Pointer to the start of an ARP packet header
*/
void DecodeARPHeader(void* InDataStart)
{
#if !defined(NO_DECODE_ARP)
ARP_Header_t* ARPHeader = (ARP_Header_t*)InDataStart;
printf_P(PSTR(" \\\r\n ARP\r\n"));
if (!(IP_COMPARE(&ARPHeader->TPA, &ServerIPAddress)) &&
!(MAC_COMPARE(&ARPHeader->THA, &ServerMACAddress)))
{
printf_P(PSTR(" + NOT ADDRESSED TO DEVICE\r\n"));
return;
}
printf_P(PSTR(" + Protocol: %x\r\n"), SwapEndian_16(ARPHeader->ProtocolType));
printf_P(PSTR(" + Operation: %u\r\n"), SwapEndian_16(ARPHeader->Operation));
if (SwapEndian_16(ARPHeader->ProtocolType) == ETHERTYPE_IPV4)
{
printf_P(PSTR(" + SHA MAC: %02X:%02X:%02X:%02X:%02X:%02X\r\n"), ARPHeader->SHA.Octets[0],
ARPHeader->SHA.Octets[1],
ARPHeader->SHA.Octets[2],
ARPHeader->SHA.Octets[3],
ARPHeader->SHA.Octets[4],
ARPHeader->SHA.Octets[5]);
printf_P(PSTR(" + SPA IP: %u.%u.%u.%u\r\n"), ARPHeader->SPA.Octets[0],
ARPHeader->SPA.Octets[1],
ARPHeader->SPA.Octets[2],
ARPHeader->SPA.Octets[3]);
printf_P(PSTR(" + THA MAC: %02X:%02X:%02X:%02X:%02X:%02X\r\n"), ARPHeader->THA.Octets[0],
ARPHeader->THA.Octets[1],
ARPHeader->THA.Octets[2],
ARPHeader->THA.Octets[3],
ARPHeader->THA.Octets[4],
ARPHeader->THA.Octets[5]);
printf_P(PSTR(" + TPA IP: %u.%u.%u.%u\r\n"), ARPHeader->TPA.Octets[0],
ARPHeader->TPA.Octets[1],
ARPHeader->TPA.Octets[2],
ARPHeader->TPA.Octets[3]);
}
#endif
}
/** Processes an ARP packet inside an Ethernet frame, and writes the appropriate response
* to the output Ethernet frame if the host is requesting the IP or MAC address of the
* virtual server device on the network.
*
* \param[in] InDataStart Pointer to the start of the incoming packet's ARP header
* \param[out] OutDataStart Pointer to the start of the outgoing packet's ARP header
*
* \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE otherwise
*/
int16_t ARP_ProcessARPPacket(void* InDataStart,
void* OutDataStart)
{
DecodeARPHeader(InDataStart);
ARP_Header_t* ARPHeaderIN = (ARP_Header_t*)InDataStart;
ARP_Header_t* ARPHeaderOUT = (ARP_Header_t*)OutDataStart;
/* Ensure that the ARP request is a IPv4 request packet */
if ((SwapEndian_16(ARPHeaderIN->ProtocolType) == ETHERTYPE_IPV4) &&
(SwapEndian_16(ARPHeaderIN->Operation) == ARP_OPERATION_REQUEST))
{
/* If the ARP packet is requesting the MAC or IP of the virtual webserver, return the response */
if (IP_COMPARE(&ARPHeaderIN->TPA, &ServerIPAddress) ||
MAC_COMPARE(&ARPHeaderIN->THA, &ServerMACAddress))
{
/* Fill out the ARP response header */
ARPHeaderOUT->HardwareType = ARPHeaderIN->HardwareType;
ARPHeaderOUT->ProtocolType = ARPHeaderIN->ProtocolType;
ARPHeaderOUT->HLEN = ARPHeaderIN->HLEN;
ARPHeaderOUT->PLEN = ARPHeaderIN->PLEN;
ARPHeaderOUT->Operation = SwapEndian_16(ARP_OPERATION_REPLY);
/* Copy over the sender MAC/IP to the target fields for the response */
ARPHeaderOUT->THA = ARPHeaderIN->SHA;
ARPHeaderOUT->TPA = ARPHeaderIN->SPA;
/* Copy over the new sender MAC/IP - MAC and IP addresses of the virtual webserver */
ARPHeaderOUT->SHA = ServerMACAddress;
ARPHeaderOUT->SPA = ServerIPAddress;
/* Return the size of the response so far */
return sizeof(ARP_Header_t);
}
}
return NO_RESPONSE;
}
/** Processes an IP packet inside an Ethernet frame, and writes the appropriate response
* to the output Ethernet frame if one is created by a sub-protocol handler.
*
* \param[in] InDataStart Pointer to the start of the incoming packet's IP header
* \param[out] OutDataStart Pointer to the start of the outgoing packet's IP header
*
* \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE if no
* response was generated, NO_PROCESS if the packet processing was deferred until the
* next Ethernet packet handler iteration
*/
int16_t IP_ProcessIPPacket(void* InDataStart,
void* OutDataStart)
{
DecodeIPHeader(InDataStart);
IP_Header_t* IPHeaderIN = (IP_Header_t*)InDataStart;
IP_Header_t* IPHeaderOUT = (IP_Header_t*)OutDataStart;
/* Header length is specified in number of longs in the packet header, convert to bytes */
uint16_t HeaderLengthBytes = (IPHeaderIN->HeaderLength * sizeof(uint32_t));
int16_t RetSize = NO_RESPONSE;
/* Check to ensure the IP packet is addressed to the virtual webserver's IP or the broadcast IP address */
if (!(IP_COMPARE(&IPHeaderIN->DestinationAddress, &ServerIPAddress)) &&
!(IP_COMPARE(&IPHeaderIN->DestinationAddress, &BroadcastIPAddress)))
{
return NO_RESPONSE;
}
/* Pass off the IP payload to the appropriate protocol processing routine */
switch (IPHeaderIN->Protocol)
{
case PROTOCOL_ICMP:
RetSize = ICMP_ProcessICMPPacket(&((uint8_t*)InDataStart)[HeaderLengthBytes],
&((uint8_t*)OutDataStart)[sizeof(IP_Header_t)]);
break;
case PROTOCOL_TCP:
RetSize = TCP_ProcessTCPPacket(InDataStart,
&((uint8_t*)InDataStart)[HeaderLengthBytes],
&((uint8_t*)OutDataStart)[sizeof(IP_Header_t)]);
break;
case PROTOCOL_UDP:
RetSize = UDP_ProcessUDPPacket(InDataStart,
&((uint8_t*)InDataStart)[HeaderLengthBytes],
&((uint8_t*)OutDataStart)[sizeof(IP_Header_t)]);
break;
}
/* Check to see if the protocol processing routine has filled out a response */
if (RetSize > 0)
{
/* Fill out the response IP packet header */
IPHeaderOUT->TotalLength = SwapEndian_16(sizeof(IP_Header_t) + RetSize);
IPHeaderOUT->TypeOfService = 0;
IPHeaderOUT->HeaderLength = (sizeof(IP_Header_t) / sizeof(uint32_t));
IPHeaderOUT->Version = 4;
IPHeaderOUT->Flags = 0;
IPHeaderOUT->FragmentOffset = 0;
IPHeaderOUT->Identification = 0;
IPHeaderOUT->HeaderChecksum = 0;
IPHeaderOUT->Protocol = IPHeaderIN->Protocol;
IPHeaderOUT->TTL = DEFAULT_TTL;
IPHeaderOUT->SourceAddress = IPHeaderIN->DestinationAddress;
IPHeaderOUT->DestinationAddress = IPHeaderIN->SourceAddress;
IPHeaderOUT->HeaderChecksum = Ethernet_Checksum16(IPHeaderOUT, sizeof(IP_Header_t));
/* Return the size of the response so far */
return (sizeof(IP_Header_t) + RetSize);
}
return RetSize;
}
