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ethanmpeterson/user_accounts.c

Last active October 16, 2018 19:12
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APSC 143 Lab 6 Code
Raw
user_accounts.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define NUM 100 //Take 100 usernames
#define MAXLEN 20 // Max username and password length
// Function declarations
int readDatabase(char *usrDB[], int pswrdDB[]);
char *getUsername();
char *getPassword();
int searchUsername(char *username, char *usernameDB[], int size);
int attemptLogin(int passwordDB[], int idx);
int hashPassword(char *password);
void deleteNewLine(char string[]);
int userNum;
int main(int argc, char **argv)
{
char *usernameDB[NUM]; // Array of pointers to strings. Will read usernames from file into this array
int passwordDB[NUM]; // Array of ints. Will read password hashes from file into this array.
int numUsers; // The number of users.
char response[MAXLEN] = {}; // Generic array for user input.
// Read in username and password
// YOUR CODE GOES HERE
// Infinite loop
while(1){
int usrIdx; // Index of target username
int loginStatus = 0; // Indicates whether passwords match
char *username; // User specified username
//-----------------------------------------------------------
// YOUR CODE GOES HERE
//-----------------------------------------------------------
readDatabase(usernameDB, passwordDB);
do {
username = getUsername(); // grab username from user input
usrIdx = searchUsername(username, usernameDB, userNum); // search the username DB for the given username and return the index of the match
} while (usrIdx == -1);
do {
loginStatus = attemptLogin(passwordDB, usrIdx); // grab password input hash it and compare against hash value in the password db
} while (!loginStatus);
printf("Logged in.\n");
printf("Press enter to log out.");
fgets(response, MAXLEN, stdin);
printf("Logged out.\n\n");
printf("Log in to another account? (Y/N)");
fgets(response, MAXLEN, stdin);
if((response[0] == 'N') || (response[0] == 'n'))
break;
}
return 0;
}
// Function definitions
void deleteNewLine(char string[]) {
if (string[strlen(string) - 1] == '\n') {
string[strlen(string) - 1] = '\0';
}
}
int readDatabase(char *usrDB[], int pswrdDB[]) {
int numUsers = 0, numPasswords = 0;
char userBuffer[MAXLEN];
FILE * usrFP; // declare usernames text file
// open username file
usrFP = fopen("/Users/ethanpeterson/Desktop/lab6/usernames.txt", "r"); // open usernames text file
if (usrFP == NULL) { // check that file was successfully retreived
printf("Could not open usernames file\n");
exit(1);
}
// read username file
while(fgets(userBuffer, MAXLEN, usrFP)) { // go through the file and grab usernames
numUsers++;
deleteNewLine(userBuffer); // remove the newline character so it doesnt interfere with comparisons
usrDB[numUsers] = (char *) malloc(strlen(userBuffer) + 1); // allocate memory for each string in the userDB array
strcpy(usrDB[numUsers], userBuffer); // copy username input into the usernameDB
}
// close username file
fclose(usrFP);
// declare password file variable
FILE * pswrdFP;
pswrdFP = fopen("/Users/ethanpeterson/Desktop/lab6/passwords.txt", "r"); // open password file in read mode
if (pswrdFP == NULL) { // check and report a failure to open the file
printf("FAILED TO OPEN PASSWORD FILE\n");
exit(1);
}
// read password file
while (!feof(pswrdFP)) { // while not at the end of the file scan in the passwords to the password db using fscanf
fscanf(pswrdFP, "%d", &pswrdDB[numPasswords]); // take in integer with %d since only hash values are stored
numPasswords++; // incriment to keep track while also making sure we are not overwriting the same spot in the array
}
// // close password file
fclose(pswrdFP);
// check number of entries the same
if (numPasswords != numUsers) {
printf("The Number of entries in each file does not match\n");
}
// return number of entries read.
userNum = numUsers; // store number of users globally outside this function
return numPasswords;
}
char *getPassword() {
char *password = (char *) malloc(MAXLEN); // reserve space in memory for the password input
printf("Enter Password:");
fgets(password, MAXLEN, stdin); // grab password
deleteNewLine(password);
return password;
}
int searchUsername(char *username, char *usernameDB[], int size) {
// replace with your code
FILE * usernameFile;
usernameFile = fopen("/Users/ethanpeterson/Desktop/lab6/usernames.txt", "r"); // open usernames file in read mode
if (usernameFile == NULL) { // check that file was successfully opened
printf("FAILED TO OPEN USER FILE\n");
exit(1);
}
for (int i = 0; i < size; i++) {
char buffer[MAXLEN]; // where file input is stored
fgets(buffer, MAXLEN, usernameFile); // grab the username in the file to be added to db
usernameDB[i] = (char *) malloc(strlen(buffer) + 1); // allocate memory for a string in space i of usernameDB
if (usernameDB[i] == NULL) {
printf("ERROR\n");
exit(1);
}
deleteNewLine(buffer);
strcpy(usernameDB[i], buffer); // copy each username from the file into usernameDB after removing newline
}
for (int j = 0; j <= size; j++) { // search the updated DB for the username passed in
if (!strcmp(usernameDB[j], username)) { // if strcmp returns 0 the strings are the same then return j
return j; // return index of the match
}
}
printf("Username not Found.\n");
return -1;
}
char *getUsername() { // returns pointer to a string of username
char *username = (char *) malloc(MAXLEN); // allocate RAM for username string
printf("Enter Username:");
fgets(username, MAXLEN, stdin);
deleteNewLine(username);
return username;
}
int attemptLogin(int passwordDB[], int idx) {
char *password = getPassword(); // prompt the user and get password input from them
int asciiSum = 0; // holds sum of ascii values of each character to calculate the hash
int n = 4891;
int hash = 0;
for (int i = 0; i < strlen(password); i++) { // calculate sum of ascii values
asciiSum += password[i];
}
asciiSum = asciiSum * asciiSum;
hash = asciiSum % n;
return passwordDB[idx] == hash; // returns 1 if the password db hash matches our calculated value and 0 if not
}
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