Update

18 files changed, 600 insertions, 0 deletions

diff --git a/Semestr 4/aisd/pracownia4/rozw2.cpp b/Semestr 4/aisd/pracownia4/rozw2.cpp
new file mode 100644
index 0000000..17562a9
--- /dev/null
+++ b/Semestr 4/aisd/pracownia4/rozw2.cpp
@@ -0,0 +1,135 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+struct treap {
+    typedef long long T;
+    treap *left = nullptr;
+    treap *right = nullptr;
+    int rank, items = 1;
+    T value;
+    T sum;
+    bool rev = false;
+
+    treap(T val = T()) : rank(rand()), value(val), sum(val) {}
+
+    inline void update() {
+        if (rev) {
+            swap(left, right);
+            if (left)   left->rev   = !left->rev;
+            if (right)  right->rev  = !right->rev;
+            rev = false;
+        }
+    }
+};
+
+inline int items(treap *t) { return t ? t->items : 0; }
+inline int sum(treap *t)   { return t ? t->sum : 0; }
+inline void recalc(treap *t) { 
+    t->items = items(t->left) + items(t->right) + 1; 
+    t->sum   = sum(t->left) + sum(t->right) + t->value;
+}
+
+pair<treap*, treap*> split(treap *t, int k) {
+    if (!t) return {nullptr, nullptr};
+    t->update();
+    if (items(t->left) < k) {
+        auto p = split(t->right, k - items(t->left) - 1);
+        t->right = p.first;
+        recalc(t);
+        return {t, p.second};
+    }
+    else {
+        auto p = split(t->left, k);
+        t->right = p.first;
+        recalc(t);
+        return {p.first, t};
+    }
+}
+
+treap* merge(treap *a, treap *b) {
+    if (!a) return b;
+    if (!b) return a;
+    a->update();
+    b->update();
+    if (a->rank > b->rank) {
+        a->right = merge(a->right, b);
+        recalc(a);
+        return a;
+    }
+    else {
+        b->left = merge(a, b->left);
+        recalc(b);
+        return b;
+    }
+}
+
+treap::T select(treap *t, int k) {
+    if (!t) return treap::T();
+    t->update();
+    int i = items(t->left);
+    if (i == k)         return t->value;
+    else if (i > k)     return select(t->left, k);
+    else                return select(t->right, k - i - 1);
+}
+
+treap *insert (treap *t, treap::T val, int k) {
+    auto p = split(t, k);
+    return merge(merge(p.first, new treap(val)), p.second);
+}
+
+treap *erase(treap *t, int k) {
+    auto p1 = split(t, k);
+    auto p2 = split(p1.second, 1);
+    return merge(p1.first, p2.second);
+}
+
+treap::T sum(treap *t, int l, int r) {
+    auto p1 = split(t, r);
+    auto p2 = split(p1.first, l);
+    return sum(p2.second);
+} 
+
+void write(treap *t) {
+    if (!t) return;
+    t->update();
+    write(t->left);
+    cout << t->value << " ";
+    write(t->right);
+}
+void destroy(treap *t) {
+    if (!t) return;
+    destroy(t->left);
+    destroy(t->right);
+    delete t;
+}
+
+treap *t = 0;
+
+int main() {
+    int n;
+    scanf("%d", &n);
+    for (int i = 0; i < n; i++) {
+        char c;
+        scanf(" %c", &c);
+        if (c == 'I') {
+            int p, x;
+            scanf("%d%d", &p, &x);
+            t = insert(t, x, p);
+        }
+        if (c == 'D') {
+            int p;
+            scanf("%d", &p);
+            t = erase(t, p - 1);
+        }
+        if (c == 'S') {
+            int l, r;
+            scanf("%d%d", &l, &r);
+            printf("ans: %lld\n", sum(t, l, r));
+        }
+        cout << "Treap:\n";
+        write(t);
+        cout << "\n";
+    }
+
+    destroy(t);
+}
\ No newline at end of file
diff --git a/Semestr 4/ask/lista6/puzzle.c b/Semestr 4/ask/lista6/puzzle.c
new file mode 100644
index 0000000..6a18d20
--- /dev/null
+++ b/Semestr 4/ask/lista6/puzzle.c
@@ -0,0 +1,28 @@
+```c=
+       0:   55 	                                pushq   %rbp
+       1:   48 89 e5 	                        movq    %rsp, %rbp
+       4:   48 83 ec 10 	                    subq    $16, %rsp         
+       8:   48 89 e0 	                        movq    %rsp, %rax        #wsk stosu to rax
+       b:   48 8d 0c fd 0f 00 00 00 	        leaq    15(,%rdi,8), %rcx #n * rozmiar longa + 15 do rcx (+15 to kwestia wyrównania/sufit)
+      13:   48 83 e1 f0 	                    andq    $-16, %rcx        #zerujemy ostatnie 4 bity
+      17:   48 29 c8 	                        subq    %rcx, %rax        #oblicz nowy wskaźnik stosu
+      1a:   48 89 c4 	                        movq    %rax, %rsp        #nowy wskaźnik wrzuć do rsp
+      1d:   48 8d 4d f8 	                    leaq    -8(%rbp), %rcx
+      21:   48 89 4c f8 f8 	                    movq    %rcx, -8(%rax,%rdi,8)
+      26:   48 c7 45 f8 00 00 00 00 	        movq    $0, -8(%rbp)
+      2e:   48 85 ff 	                        testq   %rdi, %rdi
+      31:   7e 1d 	                            jle	29 <_aframe+0x50>
+      33:   31 c9 	                            xorl    %ecx, %ecx
+      35:   66 2e 0f 1f 84 00 00 00 00 00       nopw    %cs:(%rax,%rax)
+      3f:   90                                  nop
+      40:   48 89 14 c8                         movq    %rdx, (%rax,%rcx,8)
+      44:   48 ff c1                            incq    %rcx
+      47:   48 39 cf                            cmpq    %rcx, %rdi
+      4a:   75 f4                               jne -12 <_aframe+0x40>
+      4c:   48 89 7d f8                         movq    %rdi, -8(%rbp)
+      50:   48 8b 04 f0                         movq    (%rax,%rsi,8), %rax
+      54:   48 8b 00                            movq    (%rax), %rax
+      57:   48 89 ec                            movq    %rbp, %rsp            #powrót do poprzedniej ramki
+      5a:   5d                                  popq    %rbp                  #wrzucenie do rbp poprzedniego adresu
+      5b:   c3                                  retq    
+```
\ No newline at end of file
diff --git a/Semestr 4/ask/lista6/puzzle.s b/Semestr 4/ask/lista6/puzzle.s
new file mode 100644
index 0000000..3a39398
--- /dev/null
+++ b/Semestr 4/ask/lista6/puzzle.s
@@ -0,0 +1,22 @@
+        .globl  puzzle
+	
+	.text
+puzzle:
+        push %rbp               # adres koncu ramki, callee-saved
+        xorl %eax, %eax         # zeruje %rax
+        mov %rsi, %rbp          # rbp := rsi, czyli rbp := p  
+        push %rbx               # rbx na stos, callee-saved
+        mov %rdi, %rbx          # rbx := rdi, czyli rbx := n
+        sub $24, %rsp           # rsp -= 24, czyli przesun rsp o 3 bajty w dół
+        test %rdi, %rdi         # rdi == 0?, czyli n == 0?
+        jle .L1                 # jesli tak, skocz do L1
+        lea 8(%rsp), %rsi       # w p.w. rsi := rsp + 8
+        lea (%rdi,%rdi), %rdi   # rdi := 2*rdi
+        call puzzle             # wywolanie rekurencyjne puzzle
+        add 8(%rsp), %rax       # rax := rax + *(rsp + 8)
+        add %rax, %rbx          # rbx := rbx + rax
+.L1:    mov %rbx, (%rbp)        # *rbp := rbx, czyli *p := rbx
+        add $24, %rsp           # rsp := rsp + 24 (przesun adres stacka o 3 bajty)
+        pop %rbx                # przywracamy rbx
+        pop %rbp                # przywracamy rbp
+    ret
diff --git a/Semestr 4/ask/lista6/puzzle7.s b/Semestr 4/ask/lista6/puzzle7.s
new file mode 100644
index 0000000..6d26961
--- /dev/null
+++ b/Semestr 4/ask/lista6/puzzle7.s
@@ -0,0 +1,29 @@
+        .global puzzle7
+
+        .text
+puzzle7:
+        movq %rsi, -40(%rsp)
+        movq %rdx, -32(%rsp)
+        movq %rcx, -24(%rsp)
+        movq %r8, -16(%rsp)
+        movq %r9, -8(%rsp)
+        movl $8, -72(%rsp)
+        leaq 8(%rsp), %rax
+        movq %rax, -64(%rsp)
+        leaq -48(%rsp), %rax
+        movq %rax, -56(%rsp)
+        movl $0, %eax
+        jmp .L2
+.L3:    movq -64(%rsp), %rdx
+        leaq 8(%rdx), %rcx
+        movq %rcx, -64(%rsp)
+.L4:    addq (%rdx), %rax
+.L2:    subq $1, %rdi
+        js .L6
+        cmpl $47, -72(%rsp)
+        ja .L3
+        movl -72(%rsp), %edx
+        addq -56(%rsp), %rdx
+        addl $8, -72(%rsp)
+        jmp .L4
+.L6:    ret
diff --git a/Semestr 4/ask/lista6/puzzle8.c b/Semestr 4/ask/lista6/puzzle8.c
new file mode 100644
index 0000000..4d65f9d
--- /dev/null
+++ b/Semestr 4/ask/lista6/puzzle8.c
@@ -0,0 +1,25 @@
+#include <limits.h>
+
+struct T {
+    long min;
+    long max;
+    long mean;
+};
+
+struct T puzzle8(long *a, long n);
+
+struct T decode(long *a, long n) {
+    long maks = LONG_MIN;
+    long mini = LONG_MAX;
+    long sum = 0;
+    for (int i = 0; i < n; i++) {
+        if (maks < a[i]) maks = a[i];
+        if (mini > a[i]) mini = a[i];
+        sum += a[i]; 
+    }
+    struct T ret;
+    ret.min = mini;
+    ret.max = maks;
+    ret.mean = sum / n;
+    return ret;
+}
\ No newline at end of file
diff --git a/Semestr 4/ask/lista6/puzzle8.s b/Semestr 4/ask/lista6/puzzle8.s
new file mode 100644
index 0000000..cc3805d
--- /dev/null
+++ b/Semestr 4/ask/lista6/puzzle8.s
@@ -0,0 +1,30 @@
+# rdi - adres zwracanej struktury (niejawnie)
+# rsi - *a
+# rdx - n
+
+    .global puzzle8
+
+    .text
+puzzle8:
+        movq %rdx, %r11             # r11 := n
+        xorl %r10d, %r10d           # r10 := 0
+        xorl %eax, %eax             # rax := 0
+        movq $LONG_MIN, %r8         # r8 := 0x800...
+        movq $LONG_MAX, %r9         # r9 := 0x7ff...
+.L2:    cmpq %r11, %r10             # if n <= r10
+        jge .L5                     # then jump to L5, else
+        movq (%rsi,%r10,8), %rcx    # rcx := a[r10]
+        cmpq %rcx, %r9              # if a[r10] < r9
+        cmovg %rcx, %r9             # then r9 = a[r10]
+        cmpq %rcx, %r8              # if a[r10] > r8
+        cmovl %rcx, %r8             # then r8 = a[r10]
+        addq %rcx, %rax             # rax += a[r10]
+        incq %r10                   # r10++
+        jmp .L2
+.L5:    cqto                        # jeśli rax < 0 to niech rdx zaplonie
+        movq %r9, (%rdi)            # rdi->0 := r9
+        idivq %r11                  # podziel rax przez r11, efektywnie rax /= r11
+        movq %r8, 8(%rdi)           # rdi->8 := r8
+        movq %rax, 16(%rdi)         # rdi->16 := rax
+        movq %rdi, %rax             # rax := rdi
+    ret
\ No newline at end of file
diff --git a/Semestr 4/ask/lista6/test.c b/Semestr 4/ask/lista6/test.c
new file mode 100644
index 0000000..8a84ac2
--- /dev/null
+++ b/Semestr 4/ask/lista6/test.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main() {
+    int32_t x = 0xc0000000;
+    int32_t y = x + x;
+
+    printf("%d, %d\n", x, y);
+}
\ No newline at end of file
diff --git a/Semestr 4/ask/lista6/zad7.c b/Semestr 4/ask/lista6/zad7.c
new file mode 100644
index 0000000..9072504
--- /dev/null
+++ b/Semestr 4/ask/lista6/zad7.c
@@ -0,0 +1,18 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+int wypisuj(int cnt, ...) {
+    va_list v;
+    va_start(v, cnt);
+    int sum = 0;
+    for (int i = 0; i < cnt; i++) {
+        sum += va_arg(v, int);
+    }
+    return sum;
+}
+
+int puzzle7(int cnt, ...);
+
+int main() {
+    printf("%d\n", puzzle7(10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+}
\ No newline at end of file
diff --git a/Semestr 4/ask/materiały/x86-64-psABI-1.0.pdf b/Semestr 4/ask/materiały/x86-64-psABI-1.0.pdf
new file mode 100644
index 0000000..2a5a923
--- /dev/null
+++ b/Semestr 4/ask/materiały/x86-64-psABI-1.0.pdf
diff --git a/Semestr 4/pstwo/kol1/FranciszekMalinkaKolokwium1.pdf b/Semestr 4/pstwo/kol1/FranciszekMalinkaKolokwium1.pdf
new file mode 100644
index 0000000..82c38f7
--- /dev/null
+++ b/Semestr 4/pstwo/kol1/FranciszekMalinkaKolokwium1.pdf
diff --git a/Semestr 4/sieci/pracownia2/router.c b/Semestr 4/sieci/pracownia2/router.c
new file mode 100644
index 0000000..79754b3
--- /dev/null
+++ b/Semestr 4/sieci/pracownia2/router.c
@@ -0,0 +1,212 @@
+#include <stdio.h>
+#include <errno.h>
+#include <strings.h>
+#include <string.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <poll.h>
+#include <time.h>
+#include <unistd.h>
+
+#define SERVER_PORT 54321
+#define TURN_LEN_S 5
+#define TURN_LEN_MS (1000 * TURN_LEN_S)
+#define TURN_LEN_US (1000000 * TURN_LEN_S)
+#define NS_TO_MS(X) ((long)(X) / (long)1000000)
+#define S_TO_MS(X) ((long)(X) * (long)1000)
+
+struct router_addr {
+    struct in_addr  addr;
+    uint16_t        distance;
+    uint8_t         netmask;
+};
+
+struct in_addr get_broadcast_address(struct router_addr ra) {
+    struct in_addr result = ra.addr;
+    /* bitshift by more than 31 is UB */
+    if (ra.netmask < 32) {
+        result.s_addr |= ~((1<<ra.netmask) - 1);
+    }
+    return result;
+}
+
+void pretty_print(struct router_addr ra) {
+    char ip_addr[20];
+    inet_ntop(AF_INET, &ra.addr, ip_addr, sizeof(ip_addr));
+    printf("%s/%d distance %d\n", ip_addr, ra.netmask, ra.distance);
+}
+
+/* converts string of IP with netmask in CIDR notation to router_addr */
+struct router_addr stora(char *str) {
+    struct router_addr  result;
+    char                addr[20];
+    size_t              ip_preffix = strcspn(str, "/");
+    
+    strncpy(addr, str, strlen(str));
+    addr[ip_preffix] = 0;
+    inet_pton(AF_INET, addr, &(result.addr));
+    result.netmask = atoi(str + ip_preffix + 1);
+    return result;
+}
+
+int get_socket() {
+    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sockfd < 0) {
+        fprintf(stderr, "Socket error: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    return sockfd;
+}
+
+void bind_to_port(int sockfd, uint16_t port) {
+    struct sockaddr_in server_address;
+    bzero(&server_address, sizeof(server_address));
+    server_address.sin_family       = AF_INET;
+    server_address.sin_port         = htons(port);
+    server_address.sin_addr.s_addr  = htonl(INADDR_ANY);
+    if (bind(sockfd, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) {
+        fprintf(stderr, "Bind error: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+
+    int broadcastPermission = 1;
+    setsockopt (sockfd, SOL_SOCKET, SO_BROADCAST, (void *)&broadcastPermission, sizeof(broadcastPermission));
+}
+
+uint16_t read_configuration(struct router_addr** networks) {
+    uint16_t n;
+    scanf("%hd", &n);
+    *networks = malloc(n * sizeof(struct router_addr));
+    for (int i = 0; i < n; i++) {
+        char addr[20];
+        char _dist[10];
+        uint16_t dist;
+        scanf(" %s %s %hd", addr, _dist, &dist);
+        (*networks)[i] = stora(addr);
+        (*networks)[i].distance = dist;
+    }
+    return n;
+}
+
+long get_time_interval(struct timespec start, struct timespec finish) {
+    return S_TO_MS(finish.tv_sec - start.tv_sec) + NS_TO_MS(finish.tv_nsec - start.tv_nsec);
+}
+
+int poll_modify_timeout(struct pollfd *fds, nfds_t nfd, int *timeout) {
+    if (*timeout < 0) {
+        fprintf(stderr, "poll_modify_timeout: timeout is negative.\n");
+        exit(EXIT_FAILURE);
+    }
+    
+    struct timespec start;
+    clock_gettime(CLOCK_REALTIME, &start);
+    int result = poll(fds, nfd, *timeout);
+    
+    if (result == -1) {
+        fprintf(stderr, "poll error: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    if (result == 0) {
+        *timeout = 0;
+        return 0;
+    }
+    struct timespec finish;
+    clock_gettime(CLOCK_REALTIME, &finish);
+    *timeout -= get_time_interval(start, finish);
+    printf("Timeout: %dms, time waiting: %ldms.\n", *timeout, get_time_interval(start, finish));
+    return result;
+}   
+
+/* For debug purposes only */
+void recv_and_print(int sockfd, int networks_number, struct router_addr *networks) {
+    struct sockaddr_in  sender;
+    socklen_t           sender_len = sizeof(sender);
+    uint8_t             buffer[IP_MAXPACKET + 1];
+    ssize_t datagram_len = recvfrom(sockfd, buffer, IP_MAXPACKET, 0,
+        (struct sockaddr*)&sender, &sender_len);
+    if (datagram_len < 0) {
+        fprintf(stderr, "recvfrom error: %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    for (int i = 0; i < networks_number; i++) {
+        if (networks[i].addr.s_addr == sender.sin_addr.s_addr) {
+            return;
+        }
+    }
+ 
+    char sender_ip_str[20];
+    inet_ntop(AF_INET, &(sender.sin_addr), sender_ip_str, sizeof(sender_ip_str));
+    printf("Received UDP packet from IP address: %s, port %d\n", 
+        sender_ip_str, ntohs(sender.sin_port));
+
+    buffer[datagram_len] = 0;
+    printf("%ld-byte message: +%s+\n", datagram_len, buffer);
+
+}
+
+void listen_for_routers(int sockfd, int timeout, int networks_number, struct router_addr *netowrks) {
+    printf("Listening for %dms.\n", timeout);
+    struct pollfd fds;
+    fds.fd = sockfd;
+    fds.events = POLLIN;
+    fds.revents = 0;
+    while (poll_modify_timeout(&fds, 1, &timeout)) {
+        printf("Poll returned, remaining timeout: %dms.\n", timeout);
+        recv_and_print(sockfd, networks_number, netowrks);
+    }
+    printf("Finished listening\n");
+}
+
+int send_distance_vector(int sockfd, struct in_addr network) {
+    struct sockaddr_in network_address;
+	bzero (&network_address, sizeof(network_address));
+	network_address.sin_family       = AF_INET;
+	network_address.sin_port         = htons(SERVER_PORT);
+    network_address.sin_addr         = network;
+
+	char* message = "Hello server! My name is S1\n";
+	ssize_t message_len = strlen(message);
+    int result;
+
+    char addr[20];
+    inet_ntop(AF_INET, &network, addr, sizeof(addr));
+    printf("Sending datagram to %s\n", addr);
+	if ((result = sendto(sockfd, message, message_len, 0, (struct sockaddr*) &network_address, sizeof(network_address))) != message_len) {
+		fprintf(stderr, "sendto error: %s\n", strerror(errno)); 
+		// return EXIT_FAILURE;		
+	}
+}
+
+void propagate_distance_vector(int sockfd, int networks_number, struct router_addr *networks) {
+    printf("Propagating distance vector\n");
+    for (int i = 0; i < networks_number; i++) {
+        struct in_addr broadcast_address = get_broadcast_address(networks[i]);
+        send_distance_vector(sockfd, broadcast_address);
+    }
+    printf("Distance vector propagated.\n");
+}
+
+void router_loop(int sockfd, int networks_number, struct router_addr *networks) {
+    printf("Starting the router loop...\n");
+    for (;;) {
+        listen_for_routers(sockfd, TURN_LEN_MS, networks_number, networks);
+        propagate_distance_vector(sockfd, networks_number, networks);
+    }
+}
+
+int main() {
+    struct router_addr* networks;
+    int n = read_configuration(&networks);
+    for (int i = 0; i < n; i++) {
+        pretty_print(networks[i]);
+    }
+
+    int sockfd = get_socket();
+    bind_to_port(sockfd, SERVER_PORT);
+    router_loop(sockfd, n, networks);
+    
+    close(sockfd);
+    free(networks);
+}
\ No newline at end of file
diff --git a/Semestr 4/sieci/pracownia2/udp_client.c b/Semestr 4/sieci/pracownia2/udp_client.c
new file mode 100755
index 0000000..5624484
--- /dev/null
+++ b/Semestr 4/sieci/pracownia2/udp_client.c
@@ -0,0 +1,33 @@
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+int main()
+{
+	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (sockfd < 0) {
+		fprintf(stderr, "socket error: %s\n", strerror(errno)); 
+		return EXIT_FAILURE;
+	}
+
+	struct sockaddr_in server_address;
+	bzero (&server_address, sizeof(server_address));
+	server_address.sin_family      = AF_INET;
+	server_address.sin_port        = htons(54321);
+	inet_pton(AF_INET, "192.168.1.2", &server_address.sin_addr);
+
+	char* message = "Hello server!";
+	ssize_t message_len = strlen(message);
+	if (sendto(sockfd, message, message_len, 0, (struct sockaddr*) &server_address, sizeof(server_address)) != message_len) {
+		fprintf(stderr, "sendto error: %s\n", strerror(errno)); 
+		return EXIT_FAILURE;		
+	}
+
+	close (sockfd);
+	return EXIT_SUCCESS;
+}
+	
diff --git a/Semestr 4/sieci/pracownia2/udp_server.c b/Semestr 4/sieci/pracownia2/udp_server.c
new file mode 100755
index 0000000..b5ae6d1
--- /dev/null
+++ b/Semestr 4/sieci/pracownia2/udp_server.c
@@ -0,0 +1,59 @@
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+int main()
+{
+	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (sockfd < 0) {
+		fprintf(stderr, "socket error: %s\n", strerror(errno)); 
+		return EXIT_FAILURE;
+	}
+
+	struct sockaddr_in server_address;
+	bzero (&server_address, sizeof(server_address));
+	server_address.sin_family      = AF_INET;
+	server_address.sin_port        = htons(54321);
+	server_address.sin_addr.s_addr = htonl(INADDR_ANY);
+	if (bind (sockfd, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) {
+		fprintf(stderr, "bind error: %s\n", strerror(errno)); 
+		return EXIT_FAILURE;
+	}
+
+	for (;;) {
+
+		struct sockaddr_in 	sender;	
+		socklen_t 			sender_len = sizeof(sender);
+		u_int8_t 			buffer[IP_MAXPACKET+1];
+
+		ssize_t datagram_len = recvfrom (sockfd, buffer, IP_MAXPACKET, 0, (struct sockaddr*)&sender, &sender_len);
+		if (datagram_len < 0) {
+			fprintf(stderr, "recvfrom error: %s\n", strerror(errno)); 
+			return EXIT_FAILURE;
+		}
+		
+		char sender_ip_str[20]; 
+		inet_ntop(AF_INET, &(sender.sin_addr), sender_ip_str, sizeof(sender_ip_str));
+		printf ("Received UDP packet from IP address: %s, port: %d\n", sender_ip_str, ntohs(sender.sin_port));
+
+		buffer[datagram_len] = 0;
+		printf ("%ld-byte message: +%s+\n", datagram_len, buffer);
+		
+		char* reply = "Thank you!";
+		ssize_t reply_len = strlen(reply);
+		if (sendto(sockfd, reply, reply_len, 0, (struct sockaddr*)&sender, sender_len) != reply_len) {
+			fprintf(stderr, "sendto error: %s\n", strerror(errno)); 
+			return EXIT_FAILURE;		
+		}
+
+		fflush(stdout);
+	}
+
+	close (sockfd);
+	return EXIT_SUCCESS;
+}
+
diff --git a/Semestr 4/sieci/pracownia3/p3.pdf b/Semestr 4/sieci/pracownia3/p3.pdf
new file mode 100644
index 0000000..14f1261
--- /dev/null
+++ b/Semestr 4/sieci/pracownia3/p3.pdf
diff --git a/Semestr 4/sieci/wyklady/lec3.pdf b/Semestr 4/sieci/wyklady/lec3.pdf
new file mode 100644
index 0000000..ae48ec2
--- /dev/null
+++ b/Semestr 4/sieci/wyklady/lec3.pdf
diff --git a/Semestr 4/sieci/wyklady/lec4.pdf b/Semestr 4/sieci/wyklady/lec4.pdf
new file mode 100644
index 0000000..352b71d
--- /dev/null
+++ b/Semestr 4/sieci/wyklady/lec4.pdf
diff --git a/Semestr 4/sieci/wyklady/lec5.pdf b/Semestr 4/sieci/wyklady/lec5.pdf
new file mode 100644
index 0000000..3a7b39b
--- /dev/null
+++ b/Semestr 4/sieci/wyklady/lec5.pdf
diff --git a/Semestr 4/sieci/wyklady/lec6.pdf b/Semestr 4/sieci/wyklady/lec6.pdf
new file mode 100644
index 0000000..04975ce
--- /dev/null
+++ b/Semestr 4/sieci/wyklady/lec6.pdf