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#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "bcrypt.h"
#define USER_DATABASE "./user.db"
#define SECURITY_LEVEL 12
#define SEP '|'
#define MAX_LINE_LENGTH 256
static bool
valid_char(int chr)
{
return isalnum(chr) || chr == '_' || chr == '-' || chr == '.';
}
/**
* Create a new user/password
*
* \param[in] username
* \param[in] password
*
* \return true on success (user was created) or false on error
*/
bool
create_user(const char *username, const char *password) // NOLINT
{
// check for invalid characters in username
for ( const char *ptr = username; *ptr; ++ptr ) {
if ( !valid_char(*ptr) ) {
return false;
}
}
FILE *database = fopen(USER_DATABASE, "at");
if ( database == NULL ) {
return false;
}
char hash[_PASSWORD_LEN + 1] = { 0 };
if ( bcrypt_newhash(password, SECURITY_LEVEL, hash, _PASSWORD_LEN) != 0 ) {
return false;
}
(void) fprintf(database, "%s%c%s\n", username, SEP, hash);
(void) fclose(database);
return true;
}
/**
* Check is a valid username/password exists in the user-database
*
* username A username
* password A strong password
*
* @return true, if the user was successfully authenticated, otherwise false
*/
bool
check_user(const char *const username, const char *const password) // NOLINT
{
FILE *database = fopen(USER_DATABASE, "rt");
if ( database == NULL ) {
return false;
}
const size_t username_length = strlen(username);
char line[MAX_LINE_LENGTH];
bool user_authenticated = false;
while ( !user_authenticated && fgets(line, sizeof line, database) != NULL ) {
line[strcspn(line, "\r\n")] = '\0'; // remove newline (if exists)
if ( strncmp(line, username, username_length) != 0 ) {
continue;
}
if ( line[username_length] != SEP ) {
continue;
}
if ( bcrypt_checkpass(password, &line[username_length + 1]) != 0 ) {
continue;
}
user_authenticated = true;
}
(void) fclose(database);
return user_authenticated;
}
/**
* Check if a valid username already exists in the user-database
*
* \param[in] username to be checked
*
* \return true, if the user was successfully authenticated, otherwise false
*/
bool
check_user_if_exists(const char *username)
{
FILE *database = fopen(USER_DATABASE, "rt");
if ( database == NULL ) {
return false;
}
const size_t username_length = strlen(username);
char line[MAX_LINE_LENGTH];
bool user_found = false;
while ( !user_found && fgets(line, sizeof line, database) != NULL ) {
line[strcspn(line, "\r\n")] = '\0'; // remove newline (if exists)
if ( strncmp(line, username, username_length) != 0 ) {
continue;
}
if ( line[username_length] != SEP ) {
continue;
}
user_found = true;
}
(void) fclose(database);
return user_found;
}
int
main(void)
{
if ( check_user("Thomas", "Passwort") ) {
puts("Benutzer erfolgreich überprüft!");
}
return EXIT_SUCCESS;
}
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