1 files changed, 144 insertions, 0 deletions

diff --git a/src/bcrypt-test.c b/src/bcrypt-test.c
new file mode 100644
index 0000000..57cf390
--- /dev/null
+++ b/src/bcrypt-test.c
@@ -0,0 +1,144 @@
+#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, "a");
+        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, "r");
+        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, "r");
+        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;
+}