#define ETH_HW_ADDR_LEN 6
#define IP_ADDR_LEN 4
#define ARP_FRAME_TYPE 0x0806
#define ETHER_HW_TYPE 1
#define IP_PROTO_TYPE 0x0800
#define OP_ARP_REQUEST 2

#define DEFAULT_DEVICE "eth0"

struct arp_packet {
u_char targ_hw_addr[ETH_HW_ADDR_LEN];
u_char src_hw_addr[ETH_HW_ADDR_LEN];
u_short frame_type;
u_short hw_type;
u_short prot_type;
u_char hw_addr_size;
u_char prot_addr_size;
u_short op;
u_char sndr_hw_addr[ETH_HW_ADDR_LEN];
u_char sndr_ip_addr[IP_ADDR_LEN];
u_char rcpt_hw_addr[ETH_HW_ADDR_LEN];
u_char rcpt_ip_addr[IP_ADDR_LEN];
u_char padding[18];
};

void die(char *);
void get_ip_addr(struct in_addr*,char*);
void get_hw_addr(char*,char*);

int main(int argc,char** argv){

struct in_addr src_in_addr,targ_in_addr;
struct arp_packet pkt;
struct sockaddr sa;
int sock;

if(argc != 5){
printf("%s is the program which can send ARP - protocols. ChoiX[2004] DHG Security Team\n", argv[0]);
printf("Usage: %s [sender-ip] [sender-mac] [target-ip] [target-mac]\n\n", argv[0]);
exit(0);
};

sock=socket(AF_INET,SOCK_PACKET,htons(ETH_P_RARP));
if(sock<0){
perror("Can't create socket");
exit(1);
}

pkt.frame_type = htons(ARP_FRAME_TYPE);
pkt.hw_type = htons(ETHER_HW_TYPE);
pkt.prot_type = htons(IP_PROTO_TYPE);
pkt.hw_addr_size = ETH_HW_ADDR_LEN;
pkt.prot_addr_size = IP_ADDR_LEN;
pkt.op=htons(OP_ARP_REQUEST);

get_hw_addr(pkt.targ_hw_addr,argv[4]);
get_hw_addr(pkt.rcpt_hw_addr,argv[4]);
get_hw_addr(pkt.src_hw_addr,argv[2]);
get_hw_addr(pkt.sndr_hw_addr,argv[2]);

get_ip_addr(&src_in_addr,argv[1]);
get_ip_addr(&targ_in_addr,argv[3]);

memcpy(pkt.sndr_ip_addr,&src_in_addr,IP_ADDR_LEN);
memcpy(pkt.rcpt_ip_addr,&targ_in_addr,IP_ADDR_LEN);

bzero(pkt.padding,18);

strcpy(sa.sa_data,DEFAULT_DEVICE);
if(sendto(sock,&pkt,sizeof(pkt),0,&sa,sizeof(sa)) < 0){
perror("Can't make sendto");
exit(1);
}
exit(0);
}

void die(char* str){
fprintf(stderr,"%s\n",str);
exit(1);
}

void get_ip_addr(struct in_addr* in_addr,char* str){

struct hostent *hostp;

in_addr->s_addr=inet_addr(str);
if(in_addr->s_addr == -1){
if( (hostp = gethostbyname(str)))
bcopy(hostp->h_addr,in_addr,hostp->h_length);
else {
fprintf(stderr,"Unknown host %s\n",str);
exit(1);
}
}
}

void get_hw_addr(char* buf,char* str){

int i;
char c,val;

for(i=0;i<ETH_HW_ADDR_LEN;i++){
if( !(c = tolower(*str++))) die("Invalid hardware address");
if(isdigit(c)) val = c-'0';
else if(c >= 'a' && c <= 'f') val = c-'a'+10;
else die("Invalid hardware address");

*buf = val << 4;
if( !(c = tolower(*str++))) die("Invalid hardware address");
if(isdigit(c)) val = c-'0';
else if(c >= 'a' && c <= 'f') val = c-'a'+10;
else die("Invalid hardware address");

*buf++ |= val;

if(*str == ':')str++;
}
}