From 5c974d1f80d6bbbcbbe7138fec974a79379702b2 Mon Sep 17 00:00:00 2001
From: Franciszek Malinka <franciszek.malinka@gmail.com>
Date: Tue, 16 Mar 2021 19:31:22 +0100
Subject: pracownia 1 z sieci

---
 Semestr 4/sieci/pracownia1/traceroute.c | 106 ++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 Semestr 4/sieci/pracownia1/traceroute.c

(limited to 'Semestr 4/sieci/pracownia1/traceroute.c')

diff --git a/Semestr 4/sieci/pracownia1/traceroute.c b/Semestr 4/sieci/pracownia1/traceroute.c
new file mode 100644
index 0000000..7918957
--- /dev/null
+++ b/Semestr 4/sieci/pracownia1/traceroute.c	
@@ -0,0 +1,106 @@
+#include <stdio.h>
+#include <errno.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <strings.h>
+#include <string.h>
+#include <stdlib.h>
+#include <netinet/ip_icmp.h>
+#include <assert.h>
+
+#define MAX_TTL 30
+#define MESSAGES_PER_TTL 3
+
+void print_as_bytes (unsigned char* buff, ssize_t length)
+{
+	for (ssize_t i = 0; i < length; i++, buff++)
+		printf ("%.2x ", *buff);	
+}
+
+struct sockaddr_in get_sockaddr_from_ip(char *ip) {
+    struct sockaddr_in sock;
+    bzero(&sock, sizeof(sock));
+    sock.sin_family = AF_INET;
+    if (!inet_pton(AF_INET, ip, &sock.sin_addr)) {
+        fprintf(stderr, "Given ip is invalid: %s\n", ip);
+        exit(EXIT_FAILURE);
+    }
+    return sock;
+}
+
+int create_raw_icmp_socket() {
+    int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
+    if (sockfd < 0) {
+        fprintf(stderr, "socket error: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    return sockfd;
+}
+
+uint16_t compute_icmp_checksum (const void *buff, int length)
+{
+	uint32_t sum;
+	const uint16_t* ptr = buff;
+	assert (length % 2 == 0);
+	for (sum = 0; length > 0; length -= 2)
+		sum += *ptr++;
+	sum = (sum >> 16) + (sum & 0xffff);
+	return (uint16_t)(~(sum + (sum >> 16)));
+}
+
+struct icmp create_icmp_header() {
+    static uint16_t pid = 0;
+    static uint16_t seq = 0;
+    
+    struct icmp header;
+    header.icmp_type = ICMP_ECHO;
+    header.icmp_code = 0;
+    header.icmp_id = ++pid;
+    header.icmp_seq = ++seq;
+    header.icmp_cksum = 0;
+    header.icmp_cksum = compute_icmp_checksum(
+        (uint16_t*)&header, sizeof(header));
+
+    return header;
+}
+
+void send_icmp_packet(int sockfd, struct sockaddr_in *destination, int ttl) {
+    struct icmp header = create_icmp_header();
+    setsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, sizeof(int));
+
+    printf("%ld %d\n", destination->sin_addr.s_addr, sockfd);
+    ssize_t bytes_sent = sendto(
+        sockfd,
+        &header,
+        sizeof(header),
+        0,
+        (struct sockaddr*)destination,
+        sizeof(*destination)
+    );
+    if (bytes_sent == -1) {
+        fprintf(stderr, "Error while sending ICMP packet: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    fprintf(stdout, "Bytes sent: %ld\n", bytes_sent);
+}
+
+int traceroute(struct sockaddr_in *destination) {
+    int sockfd = create_raw_icmp_socket();
+
+    struct sockaddr_in  sender;
+    socklen_t           sender_len = sizeof(sender);
+    uint8_t             buffer[IP_MAXPACKET];
+    for (int ttl = 1; ttl <= MAX_TTL; ++ttl) {
+        send_icmp_packet(sockfd, destination, ttl);
+    }
+}     
+
+int main(int argc, char * argv[]) {
+    if (argc < 2) {
+        fprintf(stderr, "Usage:\n\t%s [host ip]\n", argv[0]);
+        return 1;
+    }
+
+    struct sockaddr_in destination = get_sockaddr_from_ip(argv[1]);
+    traceroute(&destination);
+}
\ No newline at end of file
-- 
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