int enc424j600_receivecallback( uint16_t packetlen )
{
uint8_t is_the_packet_for_me = 1;
unsigned char i;
unsigned char ipproto;
//First and foremost, make sure we have a big enough packet to work with.
if (packetlen < 8) {
// ERROR: Received runt packet
return 1;
}
//macto (ignore) our mac filter handles this.
enc424j600_dumpbytes( 6 );
enc424j600_popblob( macfrom, 6 );
//Make sure it's ethernet!
if (enc424j600_pop8() != 0x08) {
// ERROR: Not an ethernet packet
return 1;
}
//Is it ARP?
if (enc424j600_pop8() == 0x06) {
HandleArp();
return 0;
}
//otherwise it's standard IP
//So, we're expecting a '45
if (enc424j600_pop8() != 0x45) {
// ERROR: Not an IP packet
return 1;
}
enc424j600_pop8(); //differentiated services field.
iptotallen = enc424j600_pop16();
enc424j600_dumpbytes( 5 ); //ID, Offset+FLAGS+TTL
ipproto = enc424j600_pop8();
enc424j600_pop16(); //header checksum
enc424j600_popblob( ipsource, 4 );
for (i = 0; i < 4; i++) {
unsigned char m = ~MyMask[i];
unsigned char ch = enc424j600_pop8();
if (ch == MyIP[i] || (ch & m) == 0xff) {
continue;
}
is_the_packet_for_me = 0;
}
//Tricky, for DHCP packets, we have to detect it even if it is not to us.
if (ipproto == 17) {
remoteport = enc424j600_pop16();
localport = enc424j600_pop16();
}
if (!is_the_packet_for_me) {
// ERROR: Packet is not for us
return 1;
}
//XXX TODO Handle IPL > 5 (IHL?)
switch(ipproto) {
// ICMP
case 1: {
HandleICMP();
break;
}
// UDP
case 17: {
HandleUDP(enc424j600_pop16());
break;
}
default: {
break;
}
}
return 0;
//finishcb:
// enc424j600_finish_callback_now();
}
void HandleDHCP( uint16_t len )
{
uint8_t tmpip[4];
uint8_t tmp[4];
uint8_t optionsleft = 48; //We only allow for up to 48 options
uint8_t is_ack_packet = 0;
uint16_t first4, second4;
POP16; //Clear out checksum
//Process DHCP!
if( POP != 2 ) return; //Not a reply?
if( POP != 1 ) return; //Not Ethernet?
POP16; //size of packets + Hops
//Make sure transaction IDs match.
enc424j600_popblob( tmp, 4 );
if( memcmp( tmp, MyMAC, 4 ) != 0 )
{
//Not our request?
return;
}
enc424j600_dumpbytes( 8 ); //time elapsed + bootpflags + Client IP address
enc424j600_popblob( tmpip, 4 ); //MY IP ADDRESS!!!
enc424j600_dumpbytes( 0x18 + 0xc0 ); //Next IP + Relay IP + Mac + Padding + server name + boot name
first4 = POP16;
second4 = POP16;
if( first4 != 0x6382 || second4 != 0x5363 )
{
return;
}
//Ok, we know we have a valid DHCP packet.
//We dont want to get stuck, so we will eventually bail if we have an issue pasrsing.
while( optionsleft-- )
{
uint8_t option = POP;
uint8_t length = POP;
switch(option)
{
case 0x35: //DHCP Message Type
{
if( length < 1 ) return;
uint8_t rqt = POP;
if( rqt == 0x02 )
{
//We have an offer, extend a request.
//We will ignore the rest of the packet.
enc424j600_finish_callback_now();
RequestNewIP( 3, tmpip, ipsource ); //Request
return;
}
else if( rqt == 0x05 ) // We received an ack, accept it.
{
//IP Is valid.
is_ack_packet = 1;
if( 0 == dhcp_seconds_remain )
dhcp_seconds_remain = 0xffff;
memcpy( MyIP, tmpip, 4 );
}
length--;
break;
}
case 0x3a: //Renewal time
{
if( length < 4 || !is_ack_packet ) break;
first4 = POP16;
second4 = POP16;
// printf( "LEASE TIME: %d %d\n", first4, second4 );
if( first4 )
{
dhcp_seconds_remain = 0xffff;
}
else
{
dhcp_seconds_remain = second4;
}
length -= 4;
break;
}
case 0x01: //Subnet mask
{
if( length < 4 || !is_ack_packet ) break;
enc424j600_popblob( MyMask, 4 );
length -= 4;
break;
}
case 0x03: //Router mask
{
if( length < 4 || !is_ack_packet ) break;
enc424j600_popblob( MyGateway, 4 );
length -= 4;
break;
}
case 0xff: //End of list.
enc424j600_finish_callback_now();
if( is_ack_packet )
GotDHCPLease();
return;
case 0x42: //Time server
case 0x06: //DNS server
default:
break;
}
enc424j600_dumpbytes( length );
}
}
static void HandleArp (void)
{
unsigned short i;
unsigned char sendermac_ip_and_targetmac[16];
// unsigned char senderip[10]; //Actually sender ip + target mac, put in one to shrink code.
unsigned short proto;
unsigned char opcode;
// unsigned char ipproto;
enc424j600_pop16(); //Hardware type
proto = enc424j600_pop16();
enc424j600_pop16(); //hwsize, protosize
opcode = enc424j600_pop16(); //XXX: This includes "code" as well, it seems.
switch( opcode )
{
// ARP Request
case 1: {
unsigned char match;
enc424j600_popblob( sendermac_ip_and_targetmac, 16 );
match = 1;
//sendhex2( 0xff );
//Target IP (check for copy)
for( i = 0; i < 4; i++ )
if( enc424j600_pop8() != MyIP[i] )
match = 0;
if( match == 0 )
return;
//We must send a response, so we termiante the packet now.
enc424j600_finish_callback_now();
enc424j600_startsend( NetGetScratch() );
send_etherlink_header( 0x0806 );
enc424j600_push16( 0x0001 ); //Ethernet
enc424j600_push16( proto ); //Protocol
enc424j600_push16( 0x0604 ); //HW size, Proto size
enc424j600_push16( 0x0002 ); //Reply
enc424j600_pushblob( MyMAC, 6 );
enc424j600_pushblob( MyIP, 4 );
enc424j600_pushblob( sendermac_ip_and_targetmac, 10 ); // do not send target mac.
enc424j600_endsend();
// Have a match!
break;
}
// ARP Reply
case 2: {
uint8_t sender_mac_and_ip_and_comp_mac[16];
enc424j600_popblob( sender_mac_and_ip_and_comp_mac, 16 );
enc424j600_finish_callback_now();
//First, make sure that we're the ones who are supposed to receive the ARP.
for( i = 0; i < 6; i++ )
{
if( sender_mac_and_ip_and_comp_mac[i+10] != MyMAC[i] )
break;
}
if( i != 6 )
break;
//We're the right recipent. Put it in the table.
memcpy( &ClientArpTable[ClientArpTablePointer], sender_mac_and_ip_and_comp_mac, 10 );
ClientArpTablePointer = (ClientArpTablePointer+1)%ARP_CLIENT_TABLE_SIZE;
break;
}
default: {
//???? don't know what to do.
return;
}
}
}
