OS1/pads/enc_client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>

void error(const char *msg) { perror(msg); exit(0); } 
void sendFile(int, char*);
void checkLen(char*, char*);
char* toString(char*);
void checkChars(char*, char*);

int main(int argc, char *argv[]) {

  int socketFD, portNumber, charsWritten, charsRead;
  struct sockaddr_in serverAddress;
  struct hostent* serverHostInfo;
  char buffer[70000];

  if (argc < 4) { fprintf(stderr,"USAGE: %s hostname port\n", argv[0]); exit(0); } 
  
  checkLen(argv[1], argv[2]);  
  char* plain = toString(argv[1]);
  char* key = toString(argv[2]);
  checkChars(plain, "plain");
  checkChars(key, "key");
  
  // Set up the server address struct
  memset((char*)&serverAddress, '\0', sizeof(serverAddress)); 

  portNumber = atoi(argv[3]); 
  serverAddress.sin_family = AF_INET; 
  serverAddress.sin_port = htons(portNumber); 
  serverHostInfo = gethostbyname("localhost"); 
  
  if (serverHostInfo == NULL) { fprintf(stderr, "CLIENT: ERROR, no such host\n"); exit(0); }

  memcpy((char*)&serverAddress.sin_addr.s_addr, (char*)serverHostInfo->h_addr, serverHostInfo->h_length);

  // Set up the socket
  socketFD = socket(AF_INET, SOCK_STREAM, 0); 
  if (socketFD < 0) error("CLIENT: ERROR opening socket");

  // Connect to server
  if (connect(socketFD, (struct sockaddr*)&serverAddress, sizeof(serverAddress)) < 0) // Connect socket to addy
    fprintf(stderr, "Cannot connect to Server: %d\n", atoi(argv[1]));

  // Check Correct Server
  send(socketFD, "enc_client", 10, 0);
  charsWritten = recv(socketFD, buffer, 12, 0);
  if(!strncmp(buffer, "Wrong Client", 12)) {
    fprintf(stderr, "Server Has Rejected the Client: %d\n", atoi(argv[3]));
    exit(1);
  }

  // Send plaintext to server
  charsWritten = send(socketFD, plain, 70001, 0); 
  if (charsWritten < 0) error("CLIENT: ERROR writing to socket");
  if (charsWritten < strlen(plain)) printf("CLIENT: WARNING: Not all data written to socket!\n");
  //printf("%d\n",charsWritten);

  // Send key to server
  charsWritten = send(socketFD, key, 70001, 0); 
  if (charsWritten < 0) error("CLIENT: ERROR writing to socket");
  if (charsWritten < strlen(key)) printf("CLIENT: WARNING: Not all data written to socket!\n"); 
  //printf("%d\n",charsWritten);

  // Get Cyphertext from server
  memset(buffer, '\0', sizeof(buffer)); 
  charsRead = recv(socketFD, buffer, sizeof(buffer) - 1, 0); 
  //printf("%d\n", charsRead);

  if (charsRead < 0) error("CLIENT: ERROR reading from socket");
  printf("%s\n", buffer);
  close(socketFD); 
  return 0;
}

char* toString(char* file) {

  int charsWritten = 0;
  char* buffer;
  size_t length;
  FILE * f = fopen (file, "rb");

  if (f)
  {
    fseek (f, 0, SEEK_END);
    length = ftell (f);
    fseek (f, 0, SEEK_SET);
    //buffer = malloc (length);
    buffer = malloc (sizeof(char) * 70001);
    memset(buffer, '\0', 70001);
    if (buffer)
    {
      fread (buffer, 1, length, f);
      buffer[length-1] = '\0';
    }
    fclose (f);
  }
  return buffer;
}

void checkLen(char* plain, char* key) {

  FILE *p = fopen(plain, "r");
  if(errno != 0) {
    perror(plain);
    exit(1);
  }
  FILE *k = fopen(key, "r");
  if(errno != 0 ) {
    perror(key);
    exit(1);
  }

  fseek(p, 0, SEEK_END);
  fseek(k, 0, SEEK_END);

  if(ftell(k) < ftell(p)) {
    fprintf(stderr, "Keyfile Too Small: exiting...\n");
    exit(1);
  }
}


void checkChars(char* str, char* type) {

  for(int i = 0; i < strlen(str); i++) {
    if(str[i] == ' ');
    else if(str[i] > 64 && str[i] < 91);
    else {
      fprintf(stderr, "Invalid Character in %s file: Exiting...\n", type);
      exit(1);
    }
  }
}