Duzy commit ze smieciami

3 files changed, 259 insertions, 0 deletions

diff --git a/semestr-4/sieci/pracownia1/makefile b/semestr-4/sieci/pracownia1/makefile
new file mode 100644
index 0000000..3c48d74
--- /dev/null
+++ b/semestr-4/sieci/pracownia1/makefile
@@ -0,0 +1,19 @@
+CC=gcc
+CFLAGS=-std=gnu17 -O2 -Wall -Wextra
+TARGET=traceroute
+
+all: $(TARGET)
+
+$(TARGET): $(TARGET).o
+	$(CC) -o $(TARGET) $(TARGET).o 
+
+
+$(TARGET).o: $(TARGET).c
+	$(CC) $(CFLAGS) -c $(TARGET).c
+
+distclean:
+	$(RM) $(TARGET)
+	$(RM) $(TARGET).o
+
+clean:
+	$(RM) $(TARGET).o
diff --git a/semestr-4/sieci/pracownia1/p1.pdf b/semestr-4/sieci/pracownia1/p1.pdf
new file mode 100644
index 0000000..4b06555
--- /dev/null
+++ b/semestr-4/sieci/pracownia1/p1.pdf
diff --git a/semestr-4/sieci/pracownia1/traceroute.c b/semestr-4/sieci/pracownia1/traceroute.c
new file mode 100644
index 0000000..0e51c14
--- /dev/null
+++ b/semestr-4/sieci/pracownia1/traceroute.c
@@ -0,0 +1,240 @@
+/* Pracownia programistyczna nr 1 - traceroute
+ * Imię i nazwisko: Franciszek Malinka
+ * Nr indeksu:      316093
+ */
+
+#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>
+#include <time.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdbool.h>
+
+#define MAX_TTL 30
+#define MESSAGES_PER_TTL 3
+#define NO_MESSAGES -1
+#define TOO_FEW_MESSAGES -2137
+
+void print_as_bytes (unsigned char* buff, ssize_t length)
+{
+	for (ssize_t i = 0; i < length; i++, buff++)
+		printf ("%.2x ", *buff);	
+}
+
+void debug_received(uint8_t *buffer, struct sockaddr_in *sender, int packet_len) {
+    char ip_str[20];
+    inet_ntop(AF_INET, &(sender->sin_addr), ip_str, sizeof(ip_str));
+
+    printf("IP packet with ICMP content from: %s\n", ip_str);
+    struct ip*  ip_header = (struct ip*) buffer;
+    ssize_t     ip_header_len = 4 * ip_header->ip_hl;
+
+    printf ("IP header: "); 
+    print_as_bytes (buffer, ip_header_len);
+    printf("\n");
+
+    printf ("IP data:   ");
+    print_as_bytes (buffer + ip_header_len, packet_len - ip_header_len);
+    printf("\n\n");
+}
+
+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(uint16_t seq) {    
+    struct icmp header;
+    header.icmp_type = ICMP_ECHO;
+    header.icmp_code = 0;
+    header.icmp_id = (uint16_t)getpid();
+    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(ttl);
+    setsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, sizeof(int));
+
+    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);
+    }
+}
+
+/* Return ip address of the sender of recceived package */
+ssize_t recv_packet(int sockfd, struct sockaddr_in *sender, uint8_t *buffer) {
+    socklen_t sender_len = sizeof(*sender);
+    ssize_t packet_len = recvfrom(sockfd, buffer, IP_MAXPACKET, 0,
+        (struct sockaddr*)sender, &sender_len);
+    
+    if (packet_len == -1) {
+        fprintf(stderr, "Error while recieving a packet: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    return packet_len;
+}
+
+void send_icmp_requests(int sockfd, struct sockaddr_in *destination, int ttl, int tries) {
+    for (int i = 0; i < tries; i++) {
+        send_icmp_packet(sockfd, destination, ttl);
+    }
+}
+
+int try_select(int sockfd, struct timeval *tv) {
+    fd_set descriptors;
+    FD_ZERO(&descriptors);
+    FD_SET(sockfd, &descriptors);
+    return select(sockfd+1, &descriptors, NULL, NULL, tv);
+}
+
+void pretty_print_router(int ttl, struct in_addr *senders, float mean_wait_time, int messages_received) {
+    char ip_str[20];
+    printf("%d.\t", ttl);
+    if (messages_received == 0) {
+        printf("*\n");
+    }
+    else {
+        for (int i = 0; i < messages_received; i++) {
+            bool already_printed = false;
+            for (int j = 0; j < i; j++) {
+                if (senders[i].s_addr == senders[j].s_addr) {
+                    already_printed = true;
+                    break;
+                }
+            }
+            if (already_printed) continue;
+            inet_ntop(AF_INET, senders + i, ip_str, sizeof(ip_str));
+            printf("%-15s ", ip_str);
+        }
+        if (messages_received < MESSAGES_PER_TTL)   printf("\t???\n");
+        else                                        printf("\t%.2fms\n", mean_wait_time);
+    }
+}
+
+// This function decapsulates important data from the IMCP replies
+void get_important_data(uint8_t *buffer, uint8_t *code, uint16_t *id, uint16_t *seq) {
+    struct ip*      ip_header = (struct ip*) buffer;
+    ssize_t         offset = 4 * ip_header->ip_hl;
+    *code = ((struct icmp *)(buffer + offset))->icmp_type;
+    if (*code != ICMP_ECHOREPLY && *code != ICMP_TIMXCEED) {
+        return;
+    } else if (*code == ICMP_TIMXCEED) {
+        offset  += ICMP_MINLEN;
+        offset  += 4 * ((struct ip *)(buffer + offset))->ip_hl;
+        *seq    = ((struct icmp *)(buffer + offset))->icmp_seq;
+        *id     = ((struct icmp *)(buffer + offset))->icmp_id;
+    } else {
+        *seq = ((struct icmp *)(buffer + offset))->icmp_seq;
+        *id = ((struct icmp *)(buffer + offset))->icmp_id;
+    }
+}
+
+// timeout in milliseconds
+float get_replies(int sockfd, long timeout, int ttl, int *messages_received, struct in_addr *senders) {
+    struct sockaddr_in  sender;
+    uint8_t             buffer[IP_MAXPACKET];
+    int                 ready;
+    long                mean_wait_time = 0;
+    struct timeval      tv; tv.tv_sec = timeout / 1000; tv.tv_usec = 0;
+    *messages_received = 0;
+
+    while ((ready = try_select(sockfd, &tv))) {
+        if (ready < 0) {
+            fprintf(stderr, "Select error: %s\n", strerror(errno));
+            exit(EXIT_FAILURE);
+        }
+
+        recv_packet(sockfd, &sender, buffer);
+        uint8_t         icmp_code = 0;
+        uint16_t        seq = 0, id = 0;
+
+        get_important_data(buffer, &icmp_code, &id, &seq);
+        if (seq == ttl) {
+            senders[(*messages_received)++] = sender.sin_addr;
+            mean_wait_time += timeout * 1000 - tv.tv_usec;
+            
+            if (*messages_received == MESSAGES_PER_TTL) break;
+        }
+    }
+    // changing from microseconds to miliseconds
+    return (float)mean_wait_time / 3.0 / 1000.0;
+}
+
+// Core of the program.
+void traceroute(struct sockaddr_in *destination) {
+    int sockfd = create_raw_icmp_socket(), messages_received = 0;
+    struct in_addr senders[MESSAGES_PER_TTL];
+
+    for (int ttl = 1; ttl <= MAX_TTL; ++ttl) {
+        send_icmp_requests(sockfd, destination, ttl, MESSAGES_PER_TTL);
+        float mean_wait_time = get_replies(sockfd, 1000, ttl, &messages_received, senders);
+        pretty_print_router(ttl, senders, mean_wait_time, messages_received);
+
+        // what if our packet branched and we got to the destination faster by some path? 
+        // we gotta make a loop, not an if
+        for (int i = 0; i < messages_received; i++) {
+            if (senders[i].s_addr == destination->sin_addr.s_addr) {
+                return;
+            }
+        }
+    }
+}     
+
+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]);
+    fprintf(stdout, "traceroute to %s, %d hops max\n", argv[1], MAX_TTL);
+    traceroute(&destination);
+
+    return 0;
+}
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