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P8/icmp-timestamp.c

+/**
+ * Practica Tema 8: ICMP-TIMESTAMP
+ *
+ * Apellido, Nombre
+ * Apellido, Nombre
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/time.h>
+#include "ip-icmp.h"
+
+#define ICMP_TIMESTAMP 13
+#define ICMP_TIMESTAMP_REPLY 14
+#define TIMEOUT 5 // Tiempo de espera en segundos
+
+void crearICMPRequest(TimeStamp *icmp_msg);
+unsigned short checksum(void *b, int len);
+void imprimeError(unsigned char type, unsigned char code);
+
+int main(int argc, char *argv[]) {
+    if (argc < 2 || argc > 3) {
+        fprintf(stderr, "Uso: %s ip [-v]\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    int verbose = (argc == 3 && strcmp(argv[2], "-v") == 0);
+    const char *ip = argv[1];
+    int sockfd;
+    struct sockaddr_in dest_addr;
+    unsigned char buffer[1024];
+
+    // Crear socket RAW para ICMP
+    sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
+    if (sockfd < 0) {
+        perror("Error al crear el socket");
+        exit(EXIT_FAILURE);
+    }
+
+    memset(&dest_addr, 0, sizeof(dest_addr));
+    dest_addr.sin_family = AF_INET;
+    if (inet_pton(AF_INET, ip, &dest_addr.sin_addr) <= 0) {
+        perror("Error al convertir la dirección IP");
+        exit(EXIT_FAILURE);
+    }
+
+    // Construir el mensaje ICMP
+    TimeStamp icmp_msg;
+    crearICMPRequest(&icmp_msg);
+
+    // En modo verbose, imprime siempre los detalles del datagrama enviado
+    if (verbose) {
+        printf("-> Type: %d\n", icmp_msg.icmpHdr.type);
+        printf("-> Code: %d\n", icmp_msg.icmpHdr.code);
+        printf("-> PID : %d\n", ntohs(icmp_msg.pid));
+        printf("-> Seq Numbr: %d\n", ntohs(icmp_msg.sequence));
+        printf("-> Originate: %u ms\n", ntohl(icmp_msg.originate));
+        printf("-> Receive: 0 ms\n");  // Los campos Receive y Transmit no están en icmp_msg
+        printf("-> Transmit: 0 ms\n");
+        printf("-> Tamanyo del Datagrama: %ld bytes\n", sizeof(TimeStamp));
+    }
+
+    // Enviar mensaje ICMP
+    printf("-> Enviando Datagrama ICMP a Destino con IP: %s\n", ip);
+    if (sendto(sockfd, &icmp_msg, sizeof(icmp_msg), 0, (struct sockaddr *)&dest_addr, sizeof(dest_addr)) < 0) {
+        perror("Error al enviar el datagrama");
+        exit(EXIT_FAILURE);
+    }
+    printf("-> Timestamp Request enviado correctamente...\n");
+
+    // Configurar timeout
+    fd_set readfds;
+    FD_ZERO(&readfds);
+    FD_SET(sockfd, &readfds);
+
+    struct timeval timeout = {TIMEOUT, 0};
+    if (select(sockfd + 1, &readfds, NULL, NULL, &timeout) <= 0) {
+        printf("-> Tiempo de espera agotado para %s\n", ip);
+        exit(EXIT_FAILURE);
+    }
+
+    // Recibir respuesta
+    TimeStampReply recv_reply;
+    socklen_t addr_len = sizeof(dest_addr);
+    if (recvfrom(sockfd, &recv_reply, sizeof(recv_reply), 0, (struct sockaddr *)&dest_addr, &addr_len) < 0) {
+        perror("Error al recibir el datagrama");
+        exit(EXIT_FAILURE);
+    }
+
+    // Verificar tipo de respuesta
+    if (recv_reply.icmpMsg.icmpHdr.type == ICMP_TIMESTAMP_REPLY && recv_reply.icmpMsg.icmpHdr.code == 0) {
+        printf("\n-> Timestamp Reply recibido desde %s\n", ip);
+
+        if (strcmp(ip, "127.0.0.1") == 0) { // Caso especial: Loopback
+            printf("-> ICMP Datagram Not Processed...\n");
+        } else {
+            unsigned long originate = ntohl(recv_reply.icmpMsg.originate);
+            unsigned long receive = recv_reply.icmpMsg.receive;
+            unsigned long transmit = recv_reply.icmpMsg.transmit;
+
+            struct timeval end_time;
+            gettimeofday(&end_time, NULL);
+            unsigned long t4 = ((unsigned long)end_time.tv_sec * 1000) + ((unsigned long)end_time.tv_usec / 1000);
+            printf("\n%lu\n", t4);
+            unsigned long rtt = (receive - originate) + (t4 - transmit);
+
+            if (verbose) {
+                printf("-> Originate: %lu ms\n", originate);
+                printf("-> Receive: %lu ms\n", receive);
+                printf("-> Transmit: %lu ms\n", transmit);
+                printf("-> RTT: %lu ms\n", rtt);
+                printf("-> TTL: %d\n", recv_reply.ipHdr.TTL);
+                printf("-> Tamanyo del Datagrama: %ld bytes\n", sizeof(TimeStampReply));
+            }
+
+            printf("-> Respuesta Correcta (Type %d, Code %d)\n", recv_reply.icmpMsg.icmpHdr.type, recv_reply.icmpMsg.icmpHdr.code);
+        }
+    } else {
+        // Caso de error genérico o inesperado
+        imprimeError(recv_reply.icmpMsg.icmpHdr.type, recv_reply.icmpMsg.icmpHdr.code);
+    }
+
+    close(sockfd);
+    return EXIT_SUCCESS;
+}
+
+// Función para inicializar el mensaje ICMP
+void crearICMPRequest(TimeStamp *icmp_msg) {
+    memset(icmp_msg, 0, sizeof(TimeStamp));
+    icmp_msg->icmpHdr.type = ICMP_TIMESTAMP;
+    icmp_msg->icmpHdr.code = 0;
+    icmp_msg->pid = htons(getpid());
+    icmp_msg->sequence = htons(0);
+
+    struct timeval start_time;
+    gettimeofday(&start_time, NULL);
+    icmp_msg->originate = htonl((start_time.tv_sec * 1000) + (start_time.tv_usec / 1000));
+    
+    icmp_msg->icmpHdr.checksum = checksum(icmp_msg, sizeof(TimeStamp));
+}
+
+// Función para calcular el checksum
+unsigned short checksum(void *b, int len) {
+    unsigned short *buf = b;
+    unsigned int sum = 0;
+    for (; len > 1; len -= 2) sum += *buf++;
+    if (len == 1) sum += *(unsigned char *)buf;
+    sum = (sum >> 16) + (sum & 0xFFFF);
+    return ~sum;
+}
+
+// Función para imprimir errores ICMP
+void imprimeError(unsigned char type, unsigned char code) {
+    const char *mensaje = ""; // Variable para almacenar el mensaje a imprimir
+
+    // Determinar el mensaje basado en el tipo y código
+    if (type == 3) { // Destination Unreachable
+        mensaje = "-> Destination Unreachable: ";
+        if (code == 0)      mensaje = "-> Destination Unreachable: Net Unreachable";   
+        else if (code == 1) mensaje = "-> Destination Unreachable: Host Unreachable";
+        else if (code == 2) mensaje = "-> Destination Unreachable: Protocol Unreachable";
+        else if (code == 3) mensaje = "-> Destination Unreachable: Port Unreachable";
+        else                mensaje = "-> Destination Unreachable: Unknown Code";
+    } else if (type == 11) { // Time Exceeded
+        mensaje = "-> Time Exceeded";
+    } else { // Otros tipos de error ICMP
+        mensaje = "-> ICMP Error: ";
+    }
+
+    // Imprimir el mensaje final
+    printf("%s (Type %d, Code %d)\n", mensaje, type, code);
+}
+