2 files changed, 159 insertions, 0 deletions

diff --git a/semestr-4/sieci/pracownia3/4pkt/config.h b/semestr-4/sieci/pracownia3/4pkt/config.h
new file mode 100644
index 0000000..42ccd89
--- /dev/null
+++ b/semestr-4/sieci/pracownia3/4pkt/config.h
@@ -0,0 +1,7 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#define DATAGRAM_LEN 1000
+#define HEADER_LEN 40
+
+#endif
diff --git a/semestr-4/sieci/pracownia3/4pkt/transport.c b/semestr-4/sieci/pracownia3/4pkt/transport.c
new file mode 100644
index 0000000..806eb4e
--- /dev/null
+++ b/semestr-4/sieci/pracownia3/4pkt/transport.c
@@ -0,0 +1,152 @@
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+#include <poll.h>
+#include <stdbool.h>
+#include "config.h"
+
+#define NS_TO_MS(X) ((long)(X) / (long)1000000)
+#define S_TO_MS(X) ((long)(X) * (long)1000)
+
+int get_socket() {
+  int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+  if (sockfd < 0) {
+    fprintf(stderr, "socket error: %s", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+  return sockfd;
+}
+
+size_t send_datagram(int sockfd, struct sockaddr_in server_address, char *buffer, size_t buffer_len) {
+  return sendto(sockfd, buffer, buffer_len, 0, (struct sockaddr*) &server_address, sizeof(server_address));
+}
+
+void send_data_request(int sockfd, struct sockaddr_in server_address, size_t pos, size_t bytes) {
+  char buffer[40];
+  sprintf(buffer, "GET %ld %ld\n", pos, bytes);
+  size_t buffer_len = strlen(buffer);
+  if (send_datagram(sockfd, server_address, buffer, buffer_len) != buffer_len) {
+    fprintf(stderr, "sendto error: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+}
+
+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_socket_modify_timeout(int sockfd, int *timeout) {
+  if (*timeout < 0) {
+    *timeout = 0;
+    return 0;
+  }
+
+  struct pollfd fds;
+  struct timespec start;
+  struct timespec finish;
+  
+  fds.fd = sockfd;
+  fds.events = POLLIN;
+  fds.revents = 0;
+  
+  clock_gettime(CLOCK_REALTIME, &start);
+  int result = poll(&fds, 1, *timeout);
+  clock_gettime(CLOCK_REALTIME, &finish);
+  
+  if (result == -1) {
+    fprintf(stderr, "poll error: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+  if (result == 0) {
+    *timeout = 0;
+    return 0;
+  }
+
+  *timeout -= get_time_interval(start, finish);
+  return result;
+}   
+
+size_t recv_message(int sockfd, char *buffer, struct sockaddr_in *sender) {
+  socklen_t sender_len = sizeof(*sender);
+  bzero(buffer, HEADER_LEN + DATAGRAM_LEN);
+  bzero(sender, sizeof(*sender));
+  size_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);
+  }
+  
+  return datagram_len;
+}
+
+inline size_t min(size_t x, size_t y) { return (x<y ? x : y); }
+
+void receive_file(int sockfd, struct sockaddr_in server_address, const char *file_name, size_t file_len) {
+  FILE *fd = fopen(file_name, "w");
+  if (!fd) {
+    fprintf(stderr, "fopen error: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+  size_t bytes_writen = 0;
+  
+  size_t recv_pos, recv_len;
+  struct sockaddr_in sender;
+  char buffer[DATAGRAM_LEN + HEADER_LEN];
+  int prev_len = 0;
+
+  while (file_len) {
+    send_data_request(sockfd, server_address, bytes_writen, min(file_len, DATAGRAM_LEN));
+    int timeout = 10;
+    while (poll_socket_modify_timeout(sockfd, &timeout)) {
+      size_t received_bytes = recv_message(sockfd, buffer, &sender);
+      if (sender.sin_addr.s_addr != server_address.sin_addr.s_addr || sender.sin_port != server_address.sin_port) continue;
+      sscanf(buffer, "DATA %ld %ld\n", &recv_pos, &recv_len);
+      if (recv_pos != bytes_writen) continue;
+      fwrite(buffer + received_bytes - recv_len, sizeof(char), recv_len, fd);  
+      file_len -= recv_len;
+      bytes_writen += recv_len;
+      break;    
+    }
+    if (prev_len != bytes_writen) {
+      prev_len = bytes_writen;
+      printf("%.3f%%\n", 100.0 * (float)(bytes_writen) / (float)(file_len+bytes_writen));
+    }
+  }
+
+  fclose(fd);
+}
+
+int main(int argc, char *argv[]) {
+  if (argc != 5) {
+    printf("Usage:\n\t%s [server ip] [server port] [output file name] [file size]\n", argv[0]);
+    return -1;
+  }
+
+  int sockfd = get_socket();
+  struct sockaddr_in server_address;
+  bzero(&server_address, sizeof(server_address));
+  server_address.sin_family = AF_INET;
+  if (!inet_pton(AF_INET, argv[1], &server_address.sin_addr)) {
+    fprintf(stderr, "Invalid ip address: %s\n", argv[1]);
+    return -1;
+  }
+  server_address.sin_port = htons(atoi(argv[2]));
+  if (server_address.sin_port == 0) {
+    fprintf(stderr, "Invalid port: %s\n", argv[2]);
+    return -1;
+  }
+
+  size_t file_len = atoi(argv[4]);
+  if (file_len == 0) {
+    printf("File len is 0, nothing to do here.\n");
+    return 0;
+  }
+
+  receive_file(sockfd, server_address, argv[3], file_len);
+}
\ No newline at end of file