/** Processes an ICMP packet inside an Ethernet frame, and writes the appropriate response
* to the output Ethernet frame if the host is issuing a ICMP ECHO request.
*
* \param[in] InDataStart Pointer to the start of the incoming packet's ICMP header
* \param[out] OutDataStart Pointer to the start of the outgoing packet's ICMP header
*
* \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE otherwise
*/
int16_t ICMP_ProcessICMPPacket(void* InDataStart,
void* OutDataStart)
{
ICMP_Header_t* ICMPHeaderIN = (ICMP_Header_t*)InDataStart;
ICMP_Header_t* ICMPHeaderOUT = (ICMP_Header_t*)OutDataStart;
DecodeICMPHeader(InDataStart);
/* Determine if the ICMP packet is an echo request (ping) */
if (ICMPHeaderIN->Type == ICMP_TYPE_ECHOREQUEST)
{
/* Fill out the ICMP response packet */
ICMPHeaderOUT->Type = ICMP_TYPE_ECHOREPLY;
ICMPHeaderOUT->Code = 0;
ICMPHeaderOUT->Checksum = 0;
ICMPHeaderOUT->Id = ICMPHeaderIN->Id;
ICMPHeaderOUT->Sequence = ICMPHeaderIN->Sequence;
intptr_t DataSize = FrameIN.FrameLength - ((((intptr_t)InDataStart + sizeof(ICMP_Header_t)) - (intptr_t)FrameIN.FrameData));
/* Copy the remaining payload to the response - echo requests should echo back any sent data */
memmove(&((uint8_t*)OutDataStart)[sizeof(ICMP_Header_t)],
&((uint8_t*)InDataStart)[sizeof(ICMP_Header_t)],
DataSize);
ICMPHeaderOUT->Checksum = Ethernet_Checksum16(ICMPHeaderOUT, (DataSize + sizeof(ICMP_Header_t)));
/* Return the size of the response so far */
return (DataSize + sizeof(ICMP_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;
}
