112 lines
3.7 KiB
C
112 lines
3.7 KiB
C
#include <arpa/inet.h>
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#include <errno.h>
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#include <netdb.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <unistd.h>
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#define SERVER_IP_ADDRESS "127.0.0.1"
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#define SERVER_PORT 10059
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#define HEADER_SIZE 4
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#define CHUNK_SIZE 1024
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#define TOTAL_CHUNKS 1024
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int main(int argc, char *argv[])
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{
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int socket_desc;
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struct sockaddr_in server;
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// Create socket
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socket_desc = socket(AF_INET, SOCK_DGRAM, 0);
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// Server address structure
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memset(&server, 0, sizeof(server));
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server.sin_family = AF_INET;
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server.sin_port = htons(SERVER_PORT);
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inet_pton(AF_INET, SERVER_IP_ADDRESS, &(server.sin_addr));
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// Send initial message to the server
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// We want the entire file initially
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sendto(socket_desc, "INI", 3, 0, (struct sockaddr *)&server, sizeof(server));
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// Ack Buffer
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char ack_buffer[TOTAL_CHUNKS];
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for (int i = 0; i < TOTAL_CHUNKS; i++) {
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ack_buffer[i] = 0; // Initialize all to not received
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}
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// Buffer for entire file
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char file_buffer[CHUNK_SIZE * TOTAL_CHUNKS];
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FILE *file = fopen("received_ugbits.txt", "w");
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listen_for_file:
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printf("Listening for file chunks...\n");
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// Set socket timeout to 5 seconds
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struct timeval timeout;
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timeout.tv_sec = 5;
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timeout.tv_usec = 0;
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setsockopt(socket_desc, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
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// Listen for file messages from the server
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while (1)
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{
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char buffer[CHUNK_SIZE + HEADER_SIZE];
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socklen_t server_len = sizeof(server);
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int recv_size = recvfrom(socket_desc, buffer, CHUNK_SIZE + HEADER_SIZE, 0, (struct sockaddr *)&server, &server_len);
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if (recv_size < 0) {
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// Timeout occurred - no message received for 5 seconds
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printf("No messages received for 5 seconds, stopping...\n");
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break;
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} else {
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buffer[recv_size] = '\0';
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char chunkNum[5];
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strncpy(chunkNum, buffer, HEADER_SIZE);
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chunkNum[HEADER_SIZE] = '\0';
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// printf("Received Chunk: %s\n", chunkNum);
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ack_buffer[atoi(chunkNum)] = 1; // Set buffer to RXed
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// Method 1: Store chunk in buffer var
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memcpy(file_buffer + (atoi(chunkNum) - 1) * CHUNK_SIZE, buffer + HEADER_SIZE, recv_size - HEADER_SIZE);
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// Method 2: Write chunk directly to file
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// fseek(file, (atoi(chunkNum) - 1) * CHUNK_SIZE, SEEK_SET);
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// fwrite(buffer + HEADER_SIZE, 1, recv_size - HEADER_SIZE, file);
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}
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}
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// If any chunk has not been received, request missing chunks
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// This is accomplished by sending the ack buffer back to the server
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int totalMissing = 0;
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for (int i = 1; i <= TOTAL_CHUNKS; i++) {
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if (ack_buffer[i] != 1) {
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totalMissing++;
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}
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}
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if (totalMissing != 0) {
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printf("Total missing chunks: %d, requesting retransmission...\n", totalMissing);
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char request[TOTAL_CHUNKS + HEADER_SIZE];
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snprintf(request, sizeof(request), "REQ");
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memcpy(request + HEADER_SIZE, ack_buffer, TOTAL_CHUNKS);
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sendto(socket_desc, request, strlen(request), 0, (struct sockaddr *)&server, sizeof(server));
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goto listen_for_file;
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}
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// If we made it here, the file must be complete.
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printf("File transfer complete!\n");
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// Method 1: Write entire buffer to file
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fwrite(file_buffer, 1, CHUNK_SIZE * TOTAL_CHUNKS, file);
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fclose(file);
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close(socket_desc);
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return 0;
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} |