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P8/prueba.c

+#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
+
+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, local_addr;
+
+    // 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);
+    }
+
+    // Configurar dirección local y hacer bind()
+    memset(&local_addr, 0, sizeof(local_addr));
+    local_addr.sin_family = AF_INET;
+    local_addr.sin_addr.s_addr = INADDR_ANY;
+    local_addr.sin_port = 0;
+
+    if (bind(sockfd, (struct sockaddr *)&local_addr, sizeof(local_addr)) < 0) {
+        perror("Error al hacer bind del socket");
+        close(sockfd);
+        exit(EXIT_FAILURE);
+    }
+
+    // Configurar dirección de destino
+    memset(&dest_addr, 0, sizeof(dest_addr));
+    dest_addr.sin_family = AF_INET;
+    dest_addr.sin_port = 0;
+    if (inet_pton(AF_INET, ip, &dest_addr.sin_addr) <= 0) {
+        perror("Error al convertir la dirección IP");
+        close(sockfd);
+        exit(EXIT_FAILURE);
+    }
+
+    // Construir el mensaje ICMP
+    TimeStamp icmp_msg;
+    crearICMPRequest(&icmp_msg);
+
+    if (verbose) {
+        printf("-> Type: %d\n", icmp_msg.icmpHdr.type);
+        printf("-> Code: %d\n", icmp_msg.icmpHdr.code);
+        printf("-> PID : %d\n", icmp_msg.pid);
+        printf("-> Seq Numbr: %d\n", ntohs(icmp_msg.sequence));
+        printf("-> Originate: %u ms\n", icmp_msg.originate);
+        printf("-> Receive: 0 ms\n");
+        printf("-> Transmit: 0 ms\n");
+        printf("-> Tamanyo del Datagrama: %ld bytes\n", sizeof(TimeStamp));
+    }
+
+    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");
+        close(sockfd);
+        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) {
+        perror("Error en select");
+        close(sockfd);
+        exit(EXIT_FAILURE);
+    }
+
+    if (!FD_ISSET(sockfd, &readfds)) {
+        printf("-> Tiempo de espera agotado para %s\n", ip);
+        close(sockfd);
+        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");
+        close(sockfd);
+        exit(EXIT_FAILURE);
+    }
+
+    printf("\n-> Timestamp Reply recibido desde %s\n", ip);
+    if (recv_reply.icmpMsg.icmpHdr.type == ICMP_TIMESTAMP_REPLY && recv_reply.icmpMsg.icmpHdr.code == 0) {
+        int originate = recv_reply.icmpMsg.originate;
+        int receive = recv_reply.icmpMsg.receive;
+        int transmit = recv_reply.icmpMsg.transmit;
+
+        struct timeval end_time;
+        gettimeofday(&end_time, NULL);
+        int t4 = (end_time.tv_sec * 1000) + (end_time.tv_usec / 1000);
+        int rtt = (receive - originate) + (t4 - transmit);
+
+        if (verbose) {
+            printf("-> Originate: %u ms\n", originate);
+            printf("-> Receive: %u ms\n", receive);
+            printf("-> Transmit: %u ms\n", transmit);
+            printf("-> RTT: %u 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 {
+        imprimeError(recv_reply.icmpMsg.icmpHdr.type, recv_reply.icmpMsg.icmpHdr.code);
+    }
+
+    close(sockfd);
+    return EXIT_SUCCESS;
+}
+
+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 = getpid();
+    icmp_msg->sequence = htons(0);
+
+    struct timeval start_time;
+    gettimeofday(&start_time, NULL);
+    icmp_msg->originate = (start_time.tv_sec * 1000) + (start_time.tv_usec / 1000);
+    icmp_msg->icmpHdr.checksum = 0; // Inicializar el campo checksum a 0.
+    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; // Paso 4: Acumulador inicializado a 0.
+
+    // Paso 2: Calcular el número de palabras de 16 bits.
+    int half_words = len / 2;
+
+    // Paso 5: Recorrer el datagrama sumando palabras de 16 bits.
+    while (half_words > 0) {
+        sum += *buf++; // Sumar la palabra actual al acumulador.
+        half_words--;  // Reducir el contador de palabras.
+    }
+
+    // Si queda un byte adicional (longitud impar), procesarlo.
+    if (len % 2 == 1) {
+        sum += *(unsigned char *)buf; // Sumar el último byte como un short.
+    }
+
+    // Sumar las partes alta y baja del acumulador (1ª vez).
+    sum = (sum >> 16) + (sum & 0xFFFF);
+
+    // Sumar nuevamente las partes alta y baja del acumulador (2ª vez).
+    sum += (sum >> 16);
+
+    // Complemento a uno.
+    return (unsigned short)(~sum);
+}
+
+void imprimeError(unsigned char type, unsigned char code) {
+    switch (type) {
+        case 3: // Destination Unreachable
+            printf("-> Destination Unreachable: ");
+            switch (code) {
+                case 0: printf("Net Unreachable\n"); break;
+                case 1: printf("Host Unreachable\n"); break;
+                case 2: printf("Protocol Unreachable\n"); break;
+                case 3: printf("Port Unreachable\n"); break;
+                default: printf("Unknown Code\n"); break;
+            }
+            break;
+        case 11:
+            printf("-> Time Exceeded\n");
+            break;
+        default:
+            printf("-> ICMP Error: Type %d, Code %d\n", type, code);
+            break;
+    }
+}