test.c

// server code for UDP socket programming
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#define IP_PROTOCOL 0
#define PORT_NO 15050
#define NET_BUF_SIZE 32
#define cipherKey 'S'
#define sendrecvflag 0
#define nofile "File Not Found!"
// function to clear buffer
void clearBuf(char* b)
{
 int i;
 for (i = 0; i < NET_BUF_SIZE; i++)
 b[i] = '\0';
}
// function to encrypt
char Cipher(char ch)
{
 return ch ^ cipherKey;
}
// function sending file
int sendFile(FILE* fp, char* buf, int s)
{
 int i, len;
 if (fp == NULL) {
 strcpy(buf, nofile);
 len = strlen(nofile);
 buf[len] = EOF;
 for (i = 0; i <= len; i++)
 buf[i] = Cipher(buf[i]);
// Downloaded by Artificial Human (artificialhuman1729@gmail.com)
// lOMoARcPSD|38904499
 return 1;
 }
 char ch, ch2;
 for (i = 0; i < s; i++) {
 ch = fgetc(fp);
 ch2 = Cipher(ch);
 buf[i] = ch2;
 if (ch == EOF)
 return 1;
 }
 return 0;
}
// driver code
int main()
{
 int sockfd, nBytes;
 struct sockaddr_in addr_con;
 int addrlen = sizeof(addr_con);
 addr_con.sin_family = AF_INET;
 addr_con.sin_port = htons(PORT_NO);
 addr_con.sin_addr.s_addr = INADDR_ANY;
 char net_buf[NET_BUF_SIZE];
 FILE* fp;
 // socket()
 sockfd = socket(AF_INET, SOCK_DGRAM, IP_PROTOCOL);
 if (sockfd < 0)
 printf("\nfile descriptor not received!!\n");
 else
 printf("\nfile descriptor %d received\n", sockfd);
 // bind()
 if (bind(sockfd, (struct sockaddr*)&addr_con, sizeof(addr_con)) == 0)
 printf("\nSuccessfully binded!\n");
 else
 printf("\nBinding Failed!\n");
 while (1) {
 printf("\nWaiting for file name...\n");
 // receive file name
// Downloaded by Artificial Human (artificialhuman1729@gmail.com)
// lOMoARcPSD|38904499
 clearBuf(net_buf);
 nBytes = recvfrom(sockfd, net_buf,
 NET_BUF_SIZE, sendrecvflag,
 (struct sockaddr*)&addr_con, &addrlen);
 fp = fopen(net_buf, "r");
 printf("\nFile Name Received: %s\n", net_buf);
 if (fp == NULL)
 printf("\nFile open failed!\n");
 else
 printf("\nFile Successfully opened!\n");
 while (1) {
 // process
 if (sendFile(fp, net_buf, NET_BUF_SIZE)) {
 sendto(sockfd, net_buf, NET_BUF_SIZE,
 sendrecvflag,
 (struct sockaddr*)&addr_con, addrlen);
 break;
 }
 // send
 sendto(sockfd, net_buf, NET_BUF_SIZE,
 sendrecvflag,
 (struct sockaddr*)&addr_con, addrlen);
 clearBuf(net_buf);
 }
 if (fp != NULL)
 fclose(fp);
 }
 return 0;
}