Redes_Ping.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <netinet/in.h>
#include <fcntl.h>

struct info {
	unsigned char IP[4];
	unsigned char MAC[6];
	unsigned char netMask[4];
	unsigned char gatewayIP[4];
	int indice;
};

int getMACfromIP(const char* argv, unsigned char *MACDestino, struct info mi, int ds);
void enviarTrama(int packet_socket, unsigned char * trama, int size, int indice);
int recibirTrama(int ds, unsigned char tramaResp[1514], struct info mi);
void whoami(struct info *agregar, struct ifreq net, int ds);
void printStruct(struct info mi);
char* GetGatewayForInterface(const char* interface);
void generaHex(unsigned char* trama, int cantidad);

int capsIP(const unsigned char *datos, int size, struct info mi, const unsigned char *MACDestino){


	/*strncpy(resultado + 15, datos, sizeof(datos));
	   printf("\n\nResultado\n" );
	   for (i = 0; i < 60; i++)
	        printf("%.2x ", resultado[i]);
	   //strncpy(stuff, resultado, sizeof(resultado));*/
	return 1;
}

// Envia packete ICMP
// Return -1 = Error | Return >0 = Ms de Respuesta
int enviarEcho(unsigned char *MACDestino, struct info mi, int ds){
	printf("Entre enviar Echo\n");
	unsigned char datosICMP[42] = {
		0x08, 0x00, 0x4d, 0x46, 0x00, 0x01, 0x00, 0x01, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
		0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x61,
		0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69
	};
	unsigned char resultado[1514];
	int i;

	printf("Sizeof(trama) %ld\n", sizeof(datosICMP));
	bzero(&resultado, 1514);
	//generaHex(resultado, 1514);
	unsigned char headerIP[] = {
		0x08, 0x00, 0x45, 0x00, 0x00, 0x3c, 0x66, 0x7a, 0x00, 0x00, 0x40, 0x01, 0x66, 0xeb, 0xc0, 0xa8, 0x00, 0xa7,
		0xc0, 0xa8, 0x00, 0x64
	};
	memcpy(resultado, MACDestino, 6);
	memcpy(resultado + 6, mi.MAC, 6);
	memcpy(resultado + 12, headerIP, sizeof(headerIP));
	memcpy(resultado + 12 + sizeof(headerIP), datosICMP, sizeof(datosICMP));
	for (i = 0; i < sizeof(headerIP) + 12 + sizeof(datosICMP); i++)
		printf("%.2x ", resultado[i]);
	printf("\n");
	enviarTrama(ds, resultado, sizeof(headerIP) + 12 + sizeof(datosICMP), mi.indice);
	unsigned char new[] = { 0x02 };
	memcpy(resultado + 40, new, 1);
	enviarTrama(ds, resultado, sizeof(headerIP) + 12 + sizeof(datosICMP), mi.indice);
	return 500;
}

int main(int argc, char *argv[]){
	struct ifreq net;
	struct info mi;
	int i, ms, packet_socket = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
	unsigned char *MACDestino;
	struct timeval tv;

	tv.tv_sec = 0;          /* 30 Secs Timeout */
	tv.tv_usec = 10000;     // Not init'ing this can cause strange errors

	if (packet_socket == -1) perror("Error en el socket");
	else{
		if (argc < 2) {
			printf("Uso: ping destino [interfaz] | eg. ping 8.8.8.8 etho1 \n");
			return 1;
		}else if (argc > 2) strcpy(net.ifr_name, argv[2]);
		else{
			printf("Introduzca nombre de la interfaz: ");
			scanf("%s", net.ifr_name);
		}
		perror("Abriendo Socket");
		setsockopt(packet_socket, SOL_SOCKET, SO_RCVTIMEO, (char*)&tv, sizeof(struct timeval));
		whoami(&mi, net, packet_socket);        //Obtener Informacion de tarjeta de Red.
		//printStruct(mi);                        // NOTE: Para Debug
		printf("\nMAC de %s: ", argv[1]);
		if (getMACfromIP(argv[1], MACDestino, mi, packet_socket) < 0) printf("Error al Obtener MAC Destino\n");
		else {
			for (i = 0; i < 6; i++) {
				printf("%.2x", MACDestino[i]);
				if (i != 5) printf(":");
			}
			printf("\n");
			ms = enviarEcho(MACDestino, mi, packet_socket);
			if (ms < 0) printf("Time Out\n");
			else printf("Respuesta! Tardo %dms\n", ms);
		}
		close(packet_socket);
	}
	return 0;
}

// Llena ARG[2] con la MAC de la direccion IP:ARG[1]. Usa ARP
// Return -1 = Error | Return 0 = Correcto
int getMACfromIP(const char* argv, unsigned char *MACDestino, struct info mi, int ds){
	char *IPRecv = strdup(argv), *p, *token, actual[10];
	unsigned char u_IP[4];
	unsigned char tramaOut[1514], tramaIn[1514];
	unsigned char arpData[] = { 0x08, 0x06, 0x00, 0x01, 0x08, 0x00, 0x06, 0x04, 0x00, 0x01 };
	struct timeval start, end;
	long mtime = 0, seconds, useconds;
	int i = 0, numbytes;

	token = strtok(IPRecv, ".");
	while ( token != NULL ) {
		sprintf(actual, "%.2x", atoi(token));
		u_IP[i++] = strtoul(actual, &p, 16);
		token = strtok(NULL, ".");
	}
	bzero(&tramaOut, 1514);
	bzero(&tramaIn, 1514);
	memcpy(tramaOut + 6, mi.MAC, 6);
	memcpy(tramaOut + 12, arpData, 10);
	memcpy(tramaOut + 22, mi.MAC, 6);
	memcpy(tramaOut + 28, mi.IP, 4);
	memcpy(tramaOut + 38, u_IP, 4);
	gettimeofday(&start, NULL);

	enviarTrama(ds, tramaOut, 60, mi.indice);       //Envia ARP
	while (mtime < 100) {                           // Recolecta ARP ó Envia Error si se cumplen 100ms
		gettimeofday(&end, NULL);
		seconds  = end.tv_sec  - start.tv_sec;
		useconds = end.tv_usec - start.tv_usec;
		mtime = ((seconds) * 1000 + useconds / 1000.0) + 0.5; // Time Control

		numbytes = recibirTrama(ds, tramaIn, mi);
		// IF Checa: Recibir Algo && Que sea ARP && Que sea Respuesta && Que sea la IP que pedi.
		if (numbytes > 0 && tramaIn[12] == 0x08 && tramaIn[13] == 0x06 && tramaIn[21] == 0x02 && !memcmp(tramaIn + 28, u_IP, 4)) {
			memcpy(MACDestino, tramaIn + 22, 6);
			return 0;
		}
	}
	return -1;
}


// Envia ARG[2]:Trama a traves de ARG[1]:Socket.
// Return -1 = Error | Return 0 = Correcto
void enviarTrama(int packet_socket, unsigned char * trama, int size, int indice){
	struct sockaddr_ll interfaz;

	memset(&interfaz, 0, sizeof(interfaz));
	interfaz.sll_family = AF_PACKET;
	interfaz.sll_protocol = htons(ETH_P_ALL);
	interfaz.sll_ifindex = indice;
	if (sendto(packet_socket, trama, size, 0, (struct sockaddr *)&interfaz, sizeof(interfaz)) < 0)
		perror("Error al enviar");
}

// Recibe Trama a traves de ARG[1]:Socket y si el destino de la trama es mi.MAC, copia la trama a ARG[2]:Trama
// Return -1 = Error | Return >0 = Numbytes Recibidos
int recibirTrama(int ds, unsigned char tramaResp[1514], struct info mi){
	unsigned char server_reply[1514];
	int i = 0, j = 0, success = 0;
	ssize_t numbytes;

	numbytes = recvfrom(ds, server_reply, 1514, MSG_DONTWAIT, NULL, NULL);
	if (numbytes > 0) {
		if (!memcmp(server_reply, mi.MAC, 6)) {
			memcpy(tramaResp, server_reply, sizeof(server_reply));
			return numbytes;
		}
	}
	return -1;
}

void generaHex(unsigned char* trama, int cantidad){
	unsigned char random[cantidad];
	int fd = open("/dev/urandom", O_RDONLY);

	read(fd, random, cantidad);
	memcpy(trama, random, cantidad);
}

// Llena ARG[1] con informacion de tarjeta de red definida en ARG[2].
void whoami(struct info *agregar, struct ifreq net, int ds){
	if (ioctl(ds, SIOCGIFINDEX, &net) == -1) perror("Error al obtener el indice");
	else agregar->indice = net.ifr_ifindex;
	if (ioctl(ds, SIOCGIFHWADDR, &net) == -1) perror("Error al obtener MAC");
	else memcpy(agregar->MAC, net.ifr_hwaddr.sa_data, 6);
	if (ioctl(ds, SIOCGIFADDR, &net) == -1) perror("Error al obtener IP");
	else memcpy(agregar->IP, net.ifr_hwaddr.sa_data + 2, 4);
	if (ioctl(ds, SIOCGIFNETMASK, &net) == -1) perror("Error al obtener NETMask");
	else memcpy(agregar->netMask, net.ifr_netmask.sa_data + 2, 4);
	memcpy(agregar->gatewayIP, GetGatewayForInterface(net.ifr_name), 6);
	return;
}

// Imprime toda la informacion de un struct info
void printStruct(struct info mi){
	int i;

	printf("IP: ");
	for (i = 0; i < 4; i++) {
		printf("%d", mi.IP[i]);
		if (i != 3) printf(".");
	}
	printf("\nMAC: ");
	for (i = 0; i < 6; i++) {
		printf("%.2x", mi.MAC[i]);
		if (i != 5) printf(":");
	}
	printf("\nnetMask: ");
	for (i = 0; i < 4; i++) {
		printf("%d", mi.netMask[i]);
		if (i != 3) printf(".");
	}
	printf("\nIndice: %d\n", mi.indice);
}

// Obtiene gateway a partir de ARG[1]:Nombre de la Interfaz
// Return gateway como cadena
char* GetGatewayForInterface(const char* interface) {
	char* gateway = NULL;
	FILE* fp = popen("netstat -rn", "r");
	char line[256] = { 0x0 };

	while (fgets(line, sizeof(line), fp) != NULL) {
		char* destination;
		destination = strndup(line, 15);
		char* iface;
		iface = strndup(line + 73, strlen(interface));
		if (strcmp("0.0.0.0        ", destination) == 0 && strcmp(iface, interface) == 0)
			gateway = strndup(line + 16, 15);
		free(destination);
		free(iface);
	}
	pclose(fp);
	return gateway;
}