rpi4-osdev/part14-spi-ethernet/kernel/arp.c
2022-07-06 19:58:16 +01:00

216 lines
5.1 KiB
C

#include "../net/enc28j60.h"
#include "../include/fb.h"
ENC_HandleTypeDef handle;
// Structure for Ethernet header
typedef struct {
uint8_t DestAddrs[6];
uint8_t SrcAddrs[6];
uint16_t type;
} EtherNetII;
// Ethernet packet types
#define ARPPACKET 0x0608
#define IPPACKET 0x0008
// Structure for an ARP Packet
typedef struct {
EtherNetII eth;
uint16_t hardware;
uint16_t protocol;
uint8_t hardwareSize;
uint8_t protocolSize;
uint16_t opCode;
uint8_t senderMAC[6];
uint8_t senderIP[4];
uint8_t targetMAC[6];
uint8_t targetIP[4];
} ARP;
// ARP OpCodes
#define ARPREPLY 0x0200
#define ARPREQUEST 0x0100
// ARP hardware types
#define ETHERNET 0x0100
// MAC address to be assigned to the ENC28J60
uint8_t myMAC[6] = { 0xc0, 0xff, 0xee, 0xc0, 0xff, 0xee };
// Router MAC is not known to start with, and requires an ARP reply to find out
uint8_t routerMAC[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
// IP address to be assigned to the ENC28J60
uint8_t deviceIP[4] = { 192, 168, 0, 66 };
// IP Address of the router, whose hardware address we will find using the ARP request
uint8_t routerIP[4] = { 192, 168, 0, 1 };
// HELPER FUNCTIONS
void *memset(void *dest, uint8_t val, uint16_t len)
{
uint8_t *ptr = dest;
while (len-- > 0)
*ptr++ = val;
return dest;
}
void *memcpy(void *dest, const void *src, uint16_t len)
{
uint8_t *d = dest;
const uint8_t *s = src;
while (len--)
*d++ = *s++;
return dest;
}
uint8_t memcmp(void *str1, void *str2, unsigned count)
{
uint8_t *s1 = str1;
uint8_t *s2 = str2;
while (count-- > 0)
{
if (*s1++ != *s2++)
return s1[-1] < s2[-1] ? -1 : 1;
}
return 0;
}
// MAIN FUNCTIONS
void SendArpPacket(uint8_t *targetIP, uint8_t *deviceMAC)
{
/* Parameters:
* targetIP - The target IP Address for the ARP request (the one whose hardware
* address we want)
* deviceMAC - The MAC address of the ENC28J60, i.e. the source MAC for the ARP
* request
*/
ARP arpPacket;
// The source of the packet will be the ENC28J60 MAC address
memcpy(arpPacket.eth.SrcAddrs, deviceMAC, 6);
// The destination is broadcast - a MAC address of FF:FF:FF:FF:FF:FF
memset(arpPacket.eth.DestAddrs, 0xFF, 6);
arpPacket.eth.type = ARPPACKET;
arpPacket.hardware = ETHERNET;
// We want an IP address resolved
arpPacket.protocol = IPPACKET;
arpPacket.hardwareSize = 0x06; // sizeof(deviceMAC);
arpPacket.protocolSize = 0x04; // sizeof(deviceIP);
arpPacket.opCode = ARPREQUEST;
// Target MAC is set to 0 as it is unknown
memset(arpPacket.targetMAC, 0, 6);
// Sender MAC is the ENC28J60's MAC address
memcpy(arpPacket.senderMAC, deviceMAC, 6);
// The target IP is the IP address we want resolved
memcpy(arpPacket.targetIP, targetIP, 4);
// Check if the last reply has come from an IP address that we want i.e. someone else is already using it
if (!memcmp(targetIP, deviceIP, 4)) {
// Yes, someone is using our IP so set the sender IP to 0.0.0.0
memset(arpPacket.senderIP, 0, 4);
} else {
// No, nobody is using our IP so we can use it confidently
memcpy(arpPacket.senderIP, deviceIP, 4);
}
// Send the packet
if (ENC_RestoreTXBuffer(&handle, sizeof(ARP)) == 0) {
debugstr("Sending ARP request.");
debugcrlf();
ENC_WriteBuffer((unsigned char *)&arpPacket, sizeof(ARP));
handle.transmitLength = sizeof(ARP);
ENC_Transmit(&handle);
}
}
void arp_test(void)
{
ARP *checkPacket;
SendArpPacket(routerIP, myMAC);
debugstr("Waiting for ARP response.");
debugcrlf();
while (1) {
while (!ENC_GetReceivedFrame(&handle));
uint16_t len = handle.RxFrameInfos.length;
uint8_t *buffer = (uint8_t *)handle.RxFrameInfos.buffer;
checkPacket = (ARP *)buffer;
if (len > 0) {
if (!memcmp(checkPacket->senderIP, routerIP, 4)) {
// Success! We have found our router's MAC address
memcpy(routerMAC, checkPacket->senderMAC, 6);
debugstr("Router MAC is ");
debughex(routerMAC[0]);
debughex(routerMAC[1]);
debughex(routerMAC[2]);
debughex(routerMAC[3]);
debughex(routerMAC[4]);
debughex(routerMAC[5]);
debugcrlf();
break;
}
}
}
}
void init_network(void)
{
handle.Init.DuplexMode = ETH_MODE_HALFDUPLEX;
handle.Init.MACAddr = myMAC;
handle.Init.ChecksumMode = ETH_CHECKSUM_BY_HARDWARE;
handle.Init.InterruptEnableBits = EIE_LINKIE | EIE_PKTIE;
debugstr("Starting network up.");
debugcrlf();
if (!ENC_Start(&handle)) {
debugstr("Could not initialise network card.");
} else {
debugstr("Setting MAC address to C0:FF:EE:C0:FF:EE.");
debugcrlf();
ENC_SetMacAddr(&handle);
debugstr("Network card successfully initialised.");
}
debugcrlf();
debugstr("Waiting for ifup... ");
while (!(handle.LinkStatus & PHSTAT2_LSTAT)) ENC_IRQHandler(&handle);
debugstr("done.");
debugcrlf();
// Re-enable global interrupts
ENC_EnableInterrupts(EIE_INTIE);
}