A school project

bonus.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pwd.h>
#include <sys/types.h>
#include <time.h>


#define emailAddrLen  33
#define IDStringLen   9
#define realNameLen   33
int main(int argc, char *argv[])
{
  // Some strings
  const char* usage = "Usage %s <login ID> <real name>\n";
  const char* current = "can't get current user name! \n";
  const char* impersonate = "\n Hey! Are you trying to impersonate someone else?\n\n";
  const char* realname = "\n Hey! Do you forget you real name?\n\n";
  const char* success = "\nCongrats, you have got the buffer overflow working on %s! \n\n";
  const char* failure = 
      ".\n.\n.\n"
      "Hmmm... looks like you have not got the buffer overflow working.\n"
      "Keep trying, once your result is correct, I will tell you.\n"
      "Happy hacking :)\n"
      ".\n.\n.\n";

  char selfEmailAddr[emailAddrLen] = "xwangc@gmu.edu";
  char IDString[IDStringLen];
  char toEmailAddr[emailAddrLen];
  char realName[realNameLen];

  struct passwd *pw;
  char* username;
  char* fullname;

  time_t rawtime;
  struct tm *timeinfo;

  // Check length of arguments
  if( argc < 3 ){
    printf(usage, argv[0]);
    exit(0);
  }

  // Check pwuid and set the results
  if((pw = getpwuid(getuid())) == NULL){
    printf(current);
    exit(1);
  }
  username = pw->pw_name;
  fullname = pw->pw_gecos;

  // Copy the arguments
  strcpy (IDString, argv[1]);
  strcpy (realName, argv[2]);

  // Checking to see if the username matches
  if(strcmp(username,IDString) != 0){
    printf(impersonate);
    exit(2);
  }

  // Make sure that the name entered starts with the fullname
  if( (strlen(realName) < strlen(fullname)) || 
      (strncmp(fullname, realName, strlen(fullname)) != 0) ){
    printf(realname);
    exit(2);
  }

  // Compare the 2 email addresses
  if(strcmp(selfEmailAddr,toEmailAddr) != 0){
    printf(failure);
    exit(1);
  }else{
    time( &rawtime );
    timeinfo = localtime( &rawtime );
    printf(success, asctime( timeinfo ));
    exit(0);
  }
}