100 lines
3.2 KiB
C
100 lines
3.2 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include <unistd.h>
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#include <netdb.h>
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#include <errno.h>
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#include <signal.h>
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#define SERVER_PORT 60019
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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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#define AWK_BUFFER_SIZE 1024
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int send_size, recv_size;
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int main(int argc, char *argv[])
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{
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int socket_desc, read_size; // socket and such
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struct sockaddr_in server, client; // one for server one for client address info
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char client_message[HEADER_SIZE + AWK_BUFFER_SIZE]; // Buffer (entire AWK buffer + requested chunk)
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socket_desc = socket(AF_INET, SOCK_DGRAM, 0);
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printf("SETUP: Socket Created\n");
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server.sin_family = AF_INET;
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server.sin_port = htons(SERVER_PORT);
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server.sin_addr.s_addr = INADDR_ANY;
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bind(socket_desc, (struct sockaddr *)&server, sizeof(server));
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printf("SETUP: Bind Completed \n\n");
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int c = sizeof(struct sockaddr_in);
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// Start waiting for any messages inbound
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FILE *file = fopen("ugbits.txt", "r");
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while (1)
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{
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recv_size = recvfrom(socket_desc, client_message, HEADER_SIZE + AWK_BUFFER_SIZE, 0, (struct sockaddr *)&client, (socklen_t *)&c);
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if (recv_size < 0)
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{
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perror("Receive Failed");
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continue;
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}
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client_message[recv_size] = '\0';
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if (strncmp(client_message, "INI", 3) == 0)
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{
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printf("Initial Send Request Received\n");
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char buffer[CHUNK_SIZE];
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int chunk_number = 1;
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size_t bytes_read;
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fseek(file, 0, SEEK_SET); // Reset file pointer to beginning
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for (int i = 0; i < TOTAL_CHUNKS; i++)
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{
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bytes_read = fread(buffer, 1, CHUNK_SIZE, file);
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char chunk_response[HEADER_SIZE + CHUNK_SIZE];
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snprintf(chunk_response, HEADER_SIZE + 1, "%04d", chunk_number);
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memcpy(chunk_response + HEADER_SIZE, buffer, bytes_read);
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send_size = sendto(socket_desc, chunk_response, HEADER_SIZE + bytes_read, 0, (struct sockaddr *)&client, c);
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chunk_number++;
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}
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}
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else if (strncmp(client_message, "REQ", 3) == 0)
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{
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char ack_buffer[AWK_BUFFER_SIZE];
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memcpy(ack_buffer, client_message + HEADER_SIZE, AWK_BUFFER_SIZE);
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printf("Retransmit Request Received\n");
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for (int i = 1; i <= TOTAL_CHUNKS; i++)
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{
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if (ack_buffer[i] != 1)
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{
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fseek(file, (i - 1) * CHUNK_SIZE, SEEK_SET);
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char buffer[CHUNK_SIZE];
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size_t bytes_read = fread(buffer, 1, CHUNK_SIZE, file);
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char chunk_response[HEADER_SIZE + CHUNK_SIZE];
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snprintf(chunk_response, HEADER_SIZE + 1, "%04d", i);
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memcpy(chunk_response + HEADER_SIZE, buffer, bytes_read);
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send_size = sendto(socket_desc, chunk_response, HEADER_SIZE + bytes_read, 0, (struct sockaddr *)&client, c);
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}
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}
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}
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}
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fclose(file);
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close(socket_desc);
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return 0;
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}
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