Diff: eth/arp.cpp

Revision:

10:f0854784e960

Child:

13:9cd54f7db57a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/eth/arp.cpp	Sun Apr 16 14:21:55 2017 +0000
@@ -0,0 +1,48 @@
+#include "mbed.h"
+#include  "log.h"
+#include  "net.h"
+#include  "eth.h"
+#include "dhcp.h"
+
+#define REQUEST   1
+#define REPLY     2
+
+__packed struct header
+{
+    int16_t  hardwareType;             //16.bit: (ar$hrd) Hardware address space (e.g., Ethernet, Packet Radio Net). Always 1.
+    int16_t  protocolType;             //16.bit: (ar$pro) Protocol address space.  For Ethernet hardware, this is from the set of type fields ether_typ$<protocol>. As held in eth.h, eg IPv4 = 0x8000.
+    int8_t   hardwareLength;           // 8.bit: (ar$hln) byte length of each hardware address. Always 6 bytes.
+    int8_t   protocolLength;           // 8.bit: (ar$pln) byte length of each protocol address. Always 4 bytes.
+    int16_t  opCode;                   //16.bit: (ar$op)  opcode (ares_op$REQUEST = 1 | ares_op$REPLY = 2), high byte transmitted first.
+    char     senderHardwareAddress[6]; //nbytes: (ar$sha) Hardware address of sender of this packet, n from the ar$hln field.
+    uint32_t senderProtocolAddress;    //mbytes: (ar$spa) Protocol address of sender of this packet, m from the ar$pln field.
+    char     targetHardwareAddress[6]; //nbytes: (ar$tha) Hardware address of target of this packet (if known).
+    uint32_t targetProtocolAddress;    //mbytes: (ar$tpa) Protocol address of target.
+};
+int ArpHandleReceivedPacket(char* pSrcMac, void * pPacket, int* pSize, char* pDstMac)
+{
+    struct header*         pHeader = (header*)pPacket;
+    int16_t           hardwareType = NetToHost16(pHeader->hardwareType);
+    int16_t           protocolType = NetToHost16(pHeader->protocolType);
+    int8_t          hardwareLength =             pHeader->hardwareLength;
+    int8_t          protocolLength =             pHeader->protocolLength;
+    int16_t                 opCode = NetToHost16(pHeader->opCode);
+    uint32_t targetProtocolAddress =             pHeader->targetProtocolAddress;
+    
+    if (hardwareType          != ETHERNET     ) return DO_NOTHING; //This is not ethernet
+    if (protocolType          != IPV4         ) return DO_NOTHING; //This is not IPv4
+    if (hardwareLength        != 6            ) return DO_NOTHING; //This is not a MAC hardware address
+    if (protocolLength        != 4            ) return DO_NOTHING; //This is not an IPv4 IP address
+    if (opCode                != REQUEST      ) return DO_NOTHING; //This is not a request
+    if (targetProtocolAddress != DhcpLocalIp  ) return DO_NOTHING; //This packet was not addressed to us
+    
+    memcpy(pHeader->targetHardwareAddress,  pHeader->senderHardwareAddress, 6);
+           pHeader->targetProtocolAddress = pHeader->senderProtocolAddress;
+    memcpy(pHeader->senderHardwareAddress,  EthLocalMac,6);
+           pHeader->senderProtocolAddress = DhcpLocalIp;
+           pHeader->opCode                = NetToHost16(REPLY);
+    
+    memcpy(pDstMac, pSrcMac, 6);
+    
+    return UNICAST;
+}