community.mysql/plugins/module_utils/user.py

from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

# This code is part of Ansible, but is an independent component.
# This particular file snippet, and this file snippet only, is BSD licensed.
# Modules you write using this snippet, which is embedded dynamically by Ansible
# still belong to the author of the module, and may assign their own license
# to the complete work.
#
# Simplified BSD License (see licenses/simplified_bsd.txt or https://opensource.org/licenses/BSD-2-Clause)

import string
import re

from ansible.module_utils.six import iteritems

from ansible_collections.community.mysql.plugins.module_utils.mysql import (
    mysql_driver,
)


class InvalidPrivsError(Exception):
    pass


def get_mode(cursor):
    cursor.execute('SELECT @@GLOBAL.sql_mode')
    result = cursor.fetchone()
    mode_str = result[0]
    if 'ANSI' in mode_str:
        mode = 'ANSI'
    else:
        mode = 'NOTANSI'
    return mode


def user_exists(cursor, user, host, host_all):
    if host_all:
        cursor.execute("SELECT count(*) FROM mysql.user WHERE user = %s", (user,))
    else:
        cursor.execute("SELECT count(*) FROM mysql.user WHERE user = %s AND host = %s", (user, host))

    count = cursor.fetchone()
    return count[0] > 0


def sanitize_requires(tls_requires):
    sanitized_requires = {}
    if tls_requires:
        for key in tls_requires.keys():
            sanitized_requires[key.upper()] = tls_requires[key]
        if any(key in ["CIPHER", "ISSUER", "SUBJECT"] for key in sanitized_requires.keys()):
            sanitized_requires.pop("SSL", None)
            sanitized_requires.pop("X509", None)
            return sanitized_requires

        if "X509" in sanitized_requires.keys():
            sanitized_requires = "X509"
        else:
            sanitized_requires = "SSL"

        return sanitized_requires
    return None


def mogrify_requires(query, params, tls_requires):
    if tls_requires:
        if isinstance(tls_requires, dict):
            k, v = zip(*tls_requires.items())
            requires_query = " AND ".join(("%s %%s" % key for key in k))
            params += v
        else:
            requires_query = tls_requires
        query = " REQUIRE ".join((query, requires_query))
    return query, params


def do_not_mogrify_requires(query, params, tls_requires):
    return query, params


def get_tls_requires(cursor, user, host):
    if user:
        if not impl.use_old_user_mgmt(cursor):
            query = "SHOW CREATE USER '%s'@'%s'" % (user, host)
        else:
            query = "SHOW GRANTS for '%s'@'%s'" % (user, host)

        cursor.execute(query)
        require_list = [tuple[0] for tuple in filter(lambda x: "REQUIRE" in x[0], cursor.fetchall())]
        require_line = require_list[0] if require_list else ""
        pattern = r"(?<=\bREQUIRE\b)(.*?)(?=(?:\bPASSWORD\b|$))"
        requires_match = re.search(pattern, require_line)
        requires = requires_match.group().strip() if requires_match else ""
        if any((requires.startswith(req) for req in ('SSL', 'X509', 'NONE'))):
            requires = requires.split()[0]
            if requires == 'NONE':
                requires = None
        else:
            import shlex

            items = iter(shlex.split(requires))
            requires = dict(zip(items, items))
        return requires or None


def get_grants(cursor, user, host):
    cursor.execute("SHOW GRANTS FOR %s@%s", (user, host))
    grants_line = list(filter(lambda x: "ON *.*" in x[0], cursor.fetchall()))[0]
    pattern = r"(?<=\bGRANT\b)(.*?)(?=(?:\bON\b))"
    grants = re.search(pattern, grants_line[0]).group().strip()
    return grants.split(", ")


def user_add(cursor, user, host, host_all, password, encrypted,
             plugin, plugin_hash_string, plugin_auth_string, new_priv,
             tls_requires, check_mode):
    # we cannot create users without a proper hostname
    if host_all:
        return False

    if check_mode:
        return True

    # Determine what user management method server uses
    old_user_mgmt = impl.use_old_user_mgmt(cursor)

    mogrify = do_not_mogrify_requires if old_user_mgmt else mogrify_requires

    if password and encrypted:
        if impl.supports_identified_by_password(cursor):
            query_with_args = "CREATE USER %s@%s IDENTIFIED BY PASSWORD %s", (user, host, password)
        else:
            query_with_args = "CREATE USER %s@%s IDENTIFIED WITH mysql_native_password AS %s", (user, host, password)
    elif password and not encrypted:
        if old_user_mgmt:
            query_with_args = "CREATE USER %s@%s IDENTIFIED BY %s", (user, host, password)
        else:
            cursor.execute("SELECT CONCAT('*', UCASE(SHA1(UNHEX(SHA1(%s)))))", (password,))
            encrypted_password = cursor.fetchone()[0]
            query_with_args = "CREATE USER %s@%s IDENTIFIED WITH mysql_native_password AS %s", (user, host, encrypted_password)
    elif plugin and plugin_hash_string:
        query_with_args = "CREATE USER %s@%s IDENTIFIED WITH %s AS %s", (user, host, plugin, plugin_hash_string)
    elif plugin and plugin_auth_string:
        query_with_args = "CREATE USER %s@%s IDENTIFIED WITH %s BY %s", (user, host, plugin, plugin_auth_string)
    elif plugin:
        query_with_args = "CREATE USER %s@%s IDENTIFIED WITH %s", (user, host, plugin)
    else:
        query_with_args = "CREATE USER %s@%s", (user, host)

    query_with_args_and_tls_requires = query_with_args + (tls_requires,)
    cursor.execute(*mogrify(*query_with_args_and_tls_requires))

    if new_priv is not None:
        for db_table, priv in iteritems(new_priv):
            privileges_grant(cursor, user, host, db_table, priv, tls_requires)
    if tls_requires is not None:
        privileges_grant(cursor, user, host, "*.*", get_grants(cursor, user, host), tls_requires)
    return True


def is_hash(password):
    ishash = False
    if len(password) == 41 and password[0] == '*':
        if frozenset(password[1:]).issubset(string.hexdigits):
            ishash = True
    return ishash


def user_mod(cursor, user, host, host_all, password, encrypted,
             plugin, plugin_hash_string, plugin_auth_string, new_priv,
             append_privs, subtract_privs, tls_requires, module, role=False, maria_role=False):
    changed = False
    msg = "User unchanged"
    grant_option = False

    # Determine what user management method server uses
    old_user_mgmt = impl.use_old_user_mgmt(cursor)

    if host_all and not role:
        hostnames = user_get_hostnames(cursor, user)
    else:
        hostnames = [host]

    for host in hostnames:
        # Handle clear text and hashed passwords.
        if not role:
            if bool(password):

                # Get a list of valid columns in mysql.user table to check if Password and/or authentication_string exist
                cursor.execute("""
                    SELECT COLUMN_NAME FROM information_schema.COLUMNS
                    WHERE TABLE_SCHEMA = 'mysql' AND TABLE_NAME = 'user' AND COLUMN_NAME IN ('Password', 'authentication_string')
                    ORDER BY COLUMN_NAME DESC LIMIT 1
                """)
                colA = cursor.fetchone()

                cursor.execute("""
                    SELECT COLUMN_NAME FROM information_schema.COLUMNS
                    WHERE TABLE_SCHEMA = 'mysql' AND TABLE_NAME = 'user' AND COLUMN_NAME IN ('Password', 'authentication_string')
                    ORDER BY COLUMN_NAME ASC  LIMIT 1
                """)
                colB = cursor.fetchone()

                # Select hash from either Password or authentication_string, depending which one exists and/or is filled
                cursor.execute("""
                    SELECT COALESCE(
                            CASE WHEN %s = '' THEN NULL ELSE %s END,
                            CASE WHEN %s = '' THEN NULL ELSE %s END
                        )
                    FROM mysql.user WHERE user = %%s AND host = %%s
                    """ % (colA[0], colA[0], colB[0], colB[0]), (user, host))
                current_pass_hash = cursor.fetchone()[0]
                if isinstance(current_pass_hash, bytes):
                    current_pass_hash = current_pass_hash.decode('ascii')

                if encrypted:
                    encrypted_password = password
                    if not is_hash(encrypted_password):
                        module.fail_json(msg="encrypted was specified however it does not appear to be a valid hash expecting: *SHA1(SHA1(your_password))")
                else:
                    if old_user_mgmt:
                        cursor.execute("SELECT PASSWORD(%s)", (password,))
                    else:
                        cursor.execute("SELECT CONCAT('*', UCASE(SHA1(UNHEX(SHA1(%s)))))", (password,))
                    encrypted_password = cursor.fetchone()[0]

                if current_pass_hash != encrypted_password:
                    msg = "Password updated"
                    if module.check_mode:
                        return (True, msg)
                    if old_user_mgmt:
                        cursor.execute("SET PASSWORD FOR %s@%s = %s", (user, host, encrypted_password))
                        msg = "Password updated (old style)"
                    else:
                        try:
                            cursor.execute("ALTER USER %s@%s IDENTIFIED WITH mysql_native_password AS %s", (user, host, encrypted_password))
                            msg = "Password updated (new style)"
                        except (mysql_driver.Error) as e:
                            # https://stackoverflow.com/questions/51600000/authentication-string-of-root-user-on-mysql
                            # Replacing empty root password with new authentication mechanisms fails with error 1396
                            if e.args[0] == 1396:
                                cursor.execute(
                                    "UPDATE mysql.user SET plugin = %s, authentication_string = %s, Password = '' WHERE User = %s AND Host = %s",
                                    ('mysql_native_password', encrypted_password, user, host)
                                )
                                cursor.execute("FLUSH PRIVILEGES")
                                msg = "Password forced update"
                            else:
                                raise e
                    changed = True

        # Handle plugin authentication
        if plugin and not role:
            cursor.execute("SELECT plugin, authentication_string FROM mysql.user "
                           "WHERE user = %s AND host = %s", (user, host))
            current_plugin = cursor.fetchone()

            update = False

            if current_plugin[0] != plugin:
                update = True

            if plugin_hash_string and current_plugin[1] != plugin_hash_string:
                update = True

            if plugin_auth_string and current_plugin[1] != plugin_auth_string:
                # this case can cause more updates than expected,
                # as plugin can hash auth_string in any way it wants
                # and there's no way to figure it out for
                # a check, so I prefer to update more often than never
                update = True

            if update:
                if plugin_hash_string:
                    query_with_args = "ALTER USER %s@%s IDENTIFIED WITH %s AS %s", (user, host, plugin, plugin_hash_string)
                elif plugin_auth_string:
                    query_with_args = "ALTER USER %s@%s IDENTIFIED WITH %s BY %s", (user, host, plugin, plugin_auth_string)
                else:
                    query_with_args = "ALTER USER %s@%s IDENTIFIED WITH %s", (user, host, plugin)

                cursor.execute(*query_with_args)
                changed = True

        # Handle privileges
        if new_priv is not None:
            curr_priv = privileges_get(cursor, user, host, maria_role)

            # If the user has privileges on a db.table that doesn't appear at all in
            # the new specification, then revoke all privileges on it.
            if not append_privs and not subtract_privs:
                for db_table, priv in iteritems(curr_priv):
                    # If the user has the GRANT OPTION on a db.table, revoke it first.
                    if "GRANT" in priv:
                        grant_option = True
                    if db_table not in new_priv:
                        if user != "root" and "PROXY" not in priv:
                            msg = "Privileges updated"
                            if module.check_mode:
                                return (True, msg)
                            privileges_revoke(cursor, user, host, db_table, priv, grant_option, maria_role)
                            changed = True

            # If the user doesn't currently have any privileges on a db.table, then
            # we can perform a straight grant operation.
            if not subtract_privs:
                for db_table, priv in iteritems(new_priv):
                    if db_table not in curr_priv:
                        msg = "New privileges granted"
                        if module.check_mode:
                            return (True, msg)
                        privileges_grant(cursor, user, host, db_table, priv, tls_requires, maria_role)
                        changed = True

            # If the db.table specification exists in both the user's current privileges
            # and in the new privileges, then we need to see if there's a difference.
            db_table_intersect = set(new_priv.keys()) & set(curr_priv.keys())
            for db_table in db_table_intersect:

                grant_privs = []
                revoke_privs = []
                if append_privs:
                    # When appending privileges, only missing privileges need to be granted. Nothing is revoked.
                    grant_privs = list(set(new_priv[db_table]) - set(curr_priv[db_table]))
                elif subtract_privs:
                    # When subtracting privileges, revoke only the intersection of requested and current privileges.
                    # No privileges are granted.
                    revoke_privs = list(set(new_priv[db_table]) & set(curr_priv[db_table]))
                else:
                    # When replacing (neither append_privs nor subtract_privs), grant all missing privileges
                    # and revoke existing privileges that were not requested.
                    grant_privs = list(set(new_priv[db_table]) - set(curr_priv[db_table]))
                    revoke_privs = list(set(curr_priv[db_table]) - set(new_priv[db_table]))
                if grant_privs == ['GRANT']:
                    # USAGE grants no privileges, it is only needed because 'WITH GRANT OPTION' cannot stand alone
                    grant_privs.append('USAGE')

                if len(grant_privs) + len(revoke_privs) > 0:
                    msg = "Privileges updated: granted %s, revoked %s" % (grant_privs, revoke_privs)
                    if module.check_mode:
                        return (True, msg)
                    if len(revoke_privs) > 0:
                        privileges_revoke(cursor, user, host, db_table, revoke_privs, grant_option, maria_role)
                    if len(grant_privs) > 0:
                        privileges_grant(cursor, user, host, db_table, grant_privs, tls_requires, maria_role)
                    changed = True

        if role:
            continue

        # Handle TLS requirements
        current_requires = get_tls_requires(cursor, user, host)
        if current_requires != tls_requires:
            msg = "TLS requires updated"
            if module.check_mode:
                return (True, msg)
            if not old_user_mgmt:
                pre_query = "ALTER USER"
            else:
                pre_query = "GRANT %s ON *.* TO" % ",".join(get_grants(cursor, user, host))

            if tls_requires is not None:
                query = " ".join((pre_query, "%s@%s"))
                query_with_args = mogrify_requires(query, (user, host), tls_requires)
            else:
                query = " ".join((pre_query, "%s@%s REQUIRE NONE"))
                query_with_args = query, (user, host)

            cursor.execute(*query_with_args)
            changed = True

    return (changed, msg)


def user_delete(cursor, user, host, host_all, check_mode):
    if check_mode:
        return True

    if host_all:
        hostnames = user_get_hostnames(cursor, user)
    else:
        hostnames = [host]

    for hostname in hostnames:
        try:
            cursor.execute("DROP USER IF EXISTS %s@%s", (user, hostname))
        except Exception:
            cursor.execute("DROP USER %s@%s", (user, hostname))

    return True


def user_get_hostnames(cursor, user):
    cursor.execute("SELECT Host FROM mysql.user WHERE user = %s", (user,))
    hostnames_raw = cursor.fetchall()
    hostnames = []

    for hostname_raw in hostnames_raw:
        hostnames.append(hostname_raw[0])

    return hostnames


def privileges_get(cursor, user, host, maria_role=False):
    """ MySQL doesn't have a better method of getting privileges aside from the
    SHOW GRANTS query syntax, which requires us to then parse the returned string.
    Here's an example of the string that is returned from MySQL:

     GRANT USAGE ON *.* TO 'user'@'localhost' IDENTIFIED BY 'pass';

    This function makes the query and returns a dictionary containing the results.
    The dictionary format is the same as that returned by privileges_unpack() below.
    """
    output = {}
    if not maria_role:
        cursor.execute("SHOW GRANTS FOR %s@%s", (user, host))
    else:
        cursor.execute("SHOW GRANTS FOR %s", (user,))
    grants = cursor.fetchall()

    def pick(x):
        if x == 'ALL PRIVILEGES':
            return 'ALL'
        else:
            return x

    for grant in grants:
        if not maria_role:
            res = re.match("""GRANT (.+) ON (.+) TO (['`"]).*\\3@(['`"]).*\\4( IDENTIFIED BY PASSWORD (['`"]).+\\6)? ?(.*)""", grant[0])
        else:
            res = re.match("""GRANT (.+) ON (.+) TO (['`"]).*\\3""", grant[0])
        if res is None:
            raise InvalidPrivsError('unable to parse the MySQL grant string: %s' % grant[0])
        privileges = res.group(1).split(",")
        privileges = [pick(x.strip()) for x in privileges]

        # Handle cases when there's privs like GRANT SELECT (colA, ...) in privs.
        # To this point, the privileges list can look like
        # ['SELECT (`A`', '`B`)', 'INSERT'] that is incorrect (SELECT statement is splitted).
        # Columns should also be sorted to compare it with desired privileges later.
        # Determine if there's a case similar to the above:
        privileges = normalize_col_grants(privileges)

        if not maria_role:
            if "WITH GRANT OPTION" in res.group(7):
                privileges.append('GRANT')
        db = res.group(2)
        output.setdefault(db, []).extend(privileges)
    return output


def normalize_col_grants(privileges):
    """Fix and sort grants on columns in privileges list

    Make ['SELECT (A, B)', 'INSERT (A, B)', 'DETELE']
    from ['SELECT (A', 'B)', 'INSERT (B', 'A)', 'DELETE'].
    See unit tests in tests/unit/plugins/modules/test_mysql_user.py
    """
    for grant in ('SELECT', 'UPDATE', 'INSERT', 'REFERENCES'):
        start, end = has_grant_on_col(privileges, grant)
        # If not, either start and end will be None
        if start is not None:
            privileges = handle_grant_on_col(privileges, start, end)

    return privileges


def has_grant_on_col(privileges, grant):
    """Check if there is a statement like SELECT (colA, colB)
    in the privilege list.

    Return (start index, end index).
    """
    # Determine elements of privileges where
    # columns are listed
    start = None
    end = None
    for n, priv in enumerate(privileges):
        if '%s (' % grant in priv:
            # We found the start element
            start = n

        if start is not None and ')' in priv:
            # We found the end element
            end = n
            break

    if start is not None and end is not None:
        # if the privileges list consist of, for example,
        # ['SELECT (A', 'B), 'INSERT'], return indexes of related elements
        return start, end
    else:
        # If start and end position is the same element,
        # it means there's expression like 'SELECT (A)',
        # so no need to handle it
        return None, None


def handle_grant_on_col(privileges, start, end):
    """Handle cases when the privs like SELECT (colA, ...) is in the privileges list."""
    # When the privileges list look like ['SELECT (colA,', 'colB)']
    # (Notice that the statement is splitted)
    if start != end:
        output = list(privileges[:start])

        select_on_col = ', '.join(privileges[start:end + 1])

        select_on_col = sort_column_order(select_on_col)

        output.append(select_on_col)

        output.extend(privileges[end + 1:])

    # When it look like it should be, e.g. ['SELECT (colA, colB)'],
    # we need to be sure, the columns is sorted
    else:
        output = list(privileges)
        output[start] = sort_column_order(output[start])

    return output


def sort_column_order(statement):
    """Sort column order in grants like SELECT (colA, colB, ...).

    MySQL changes columns order like below:
    ---------------------------------------
    mysql> GRANT SELECT (testColA, testColB), INSERT ON `testDb`.`testTable` TO 'testUser'@'localhost';
    Query OK, 0 rows affected (0.04 sec)

    mysql> flush privileges;
    Query OK, 0 rows affected (0.00 sec)

    mysql> SHOW GRANTS FOR testUser@localhost;
    +---------------------------------------------------------------------------------------------+
    | Grants for testUser@localhost                                                               |
    +---------------------------------------------------------------------------------------------+
    | GRANT USAGE ON *.* TO 'testUser'@'localhost'                                                |
    | GRANT SELECT (testColB, testColA), INSERT ON `testDb`.`testTable` TO 'testUser'@'localhost' |
    +---------------------------------------------------------------------------------------------+

    We should sort columns in our statement, otherwise the module always will return
    that the state has changed.
    """
    # 1. Extract stuff inside ()
    # 2. Split
    # 3. Sort
    # 4. Put between () and return

    # "SELECT/UPDATE/.. (colA, colB) => "colA, colB"
    tmp = statement.split('(')
    priv_name = tmp[0]
    columns = tmp[1].rstrip(')')

    # "colA, colB" => ["colA", "colB"]
    columns = columns.split(',')

    for i, col in enumerate(columns):
        col = col.strip()
        columns[i] = col.strip('`')

    columns.sort()
    return '%s(%s)' % (priv_name, ', '.join(columns))


def privileges_unpack(priv, mode, ensure_usage=True):
    """ Take a privileges string, typically passed as a parameter, and unserialize
    it into a dictionary, the same format as privileges_get() above. We have this
    custom format to avoid using YAML/JSON strings inside YAML playbooks. Example
    of a privileges string:

     mydb.*:INSERT,UPDATE/anotherdb.*:SELECT/yetanother.*:ALL

    The privilege USAGE stands for no privileges, so we add that in on *.* if it's
    not specified in the string, as MySQL will always provide this by default.
    """
    if mode == 'ANSI':
        quote = '"'
    else:
        quote = '`'
    output = {}
    privs = []
    for item in priv.strip().split('/'):
        pieces = item.strip().rsplit(':', 1)
        dbpriv = pieces[0].rsplit(".", 1)

        # Check for FUNCTION or PROCEDURE object types
        parts = dbpriv[0].split(" ", 1)
        object_type = ''
        if len(parts) > 1 and (parts[0] == 'FUNCTION' or parts[0] == 'PROCEDURE'):
            object_type = parts[0] + ' '
            dbpriv[0] = parts[1]

        # Do not escape if privilege is for database or table, i.e.
        # neither quote *. nor .*
        for i, side in enumerate(dbpriv):
            if side.strip('`') != '*':
                dbpriv[i] = '%s%s%s' % (quote, side.strip('`'), quote)
        pieces[0] = object_type + '.'.join(dbpriv)

        if '(' in pieces[1]:
            output[pieces[0]] = re.split(r',\s*(?=[^)]*(?:\(|$))', pieces[1].upper())
            for i in output[pieces[0]]:
                privs.append(re.sub(r'\s*\(.*\)', '', i))
        else:
            output[pieces[0]] = pieces[1].upper().split(',')
            privs = output[pieces[0]]

        # Handle cases when there's privs like GRANT SELECT (colA, ...) in privs.
        output[pieces[0]] = normalize_col_grants(output[pieces[0]])

    if ensure_usage and '*.*' not in output:
        output['*.*'] = ['USAGE']

    return output


def privileges_revoke(cursor, user, host, db_table, priv, grant_option, maria_role=False):
    # Escape '%' since mysql db.execute() uses a format string
    db_table = db_table.replace('%', '%%')
    if grant_option:
        query = ["REVOKE GRANT OPTION ON %s" % db_table]
        if not maria_role:
            query.append("FROM %s@%s")
        else:
            query.append("FROM %s")

        query = ' '.join(query)
        cursor.execute(query, (user, host))
    priv_string = ",".join([p for p in priv if p not in ('GRANT', )])
    query = ["REVOKE %s ON %s" % (priv_string, db_table)]

    if not maria_role:
        query.append("FROM %s@%s")
        params = (user, host)
    else:
        query.append("FROM %s")
        params = (user,)

    query = ' '.join(query)
    cursor.execute(query, params)
    cursor.execute("FLUSH PRIVILEGES")


def privileges_grant(cursor, user, host, db_table, priv, tls_requires, maria_role=False):
    # Escape '%' since mysql db.execute uses a format string and the
    # specification of db and table often use a % (SQL wildcard)
    db_table = db_table.replace('%', '%%')
    priv_string = ",".join([p for p in priv if p not in ('GRANT', )])
    query = ["GRANT %s ON %s" % (priv_string, db_table)]

    if not maria_role:
        query.append("TO %s@%s")
        params = (user, host)
    else:
        query.append("TO %s")
        params = (user)

    if tls_requires and impl.use_old_user_mgmt(cursor):
        query, params = mogrify_requires(" ".join(query), params, tls_requires)
        query = [query]
    if 'GRANT' in priv:
        query.append("WITH GRANT OPTION")
    query = ' '.join(query)

    if isinstance(params, str):
        params = (params,)

    try:
        cursor.execute(query, params)
    except (mysql_driver.ProgrammingError, mysql_driver.OperationalError, mysql_driver.InternalError) as e:
        raise InvalidPrivsError("Error granting privileges, invalid priv string: %s" % priv_string)


def convert_priv_dict_to_str(priv):
    """Converts privs dictionary to string of certain format.

    Args:
        priv (dict): Dict of privileges that needs to be converted to string.

    Returns:
        priv (str): String representation of input argument.
    """
    priv_list = ['%s:%s' % (key, val) for key, val in iteritems(priv)]

    return '/'.join(priv_list)


# Alter user is supported since MySQL 5.6 and MariaDB 10.2.0
def server_supports_alter_user(cursor):
    """Check if the server supports ALTER USER statement or doesn't.

    Args:
        cursor (cursor): DB driver cursor object.

    Returns: True if supports, False otherwise.
    """
    cursor.execute("SELECT VERSION()")
    version_str = cursor.fetchone()[0]
    version = version_str.split('.')

    if 'mariadb' in version_str.lower():
        # MariaDB 10.2 and later
        if int(version[0]) * 1000 + int(version[1]) >= 10002:
            return True
        else:
            return False
    else:
        # MySQL 5.6 and later
        if int(version[0]) * 1000 + int(version[1]) >= 5006:
            return True
        else:
            return False


def get_resource_limits(cursor, user, host):
    """Get user resource limits.

    Args:
        cursor (cursor): DB driver cursor object.
        user (str): User name.
        host (str): User host name.

    Returns: Dictionary containing current resource limits.
    """

    query = ('SELECT max_questions AS MAX_QUERIES_PER_HOUR, '
             'max_updates AS MAX_UPDATES_PER_HOUR, '
             'max_connections AS MAX_CONNECTIONS_PER_HOUR, '
             'max_user_connections AS MAX_USER_CONNECTIONS '
             'FROM mysql.user WHERE User = %s AND Host = %s')
    cursor.execute(query, (user, host))
    res = cursor.fetchone()

    if not res:
        return None

    current_limits = {
        'MAX_QUERIES_PER_HOUR': res[0],
        'MAX_UPDATES_PER_HOUR': res[1],
        'MAX_CONNECTIONS_PER_HOUR': res[2],
        'MAX_USER_CONNECTIONS': res[3],
    }
    return current_limits


def match_resource_limits(module, current, desired):
    """Check and match limits.

    Args:
        module (AnsibleModule): Ansible module object.
        current (dict): Dictionary with current limits.
        desired (dict): Dictionary with desired limits.

    Returns: Dictionary containing parameters that need to change.
    """

    if not current:
        # It means the user does not exists, so we need
        # to set all limits after its creation
        return desired

    needs_to_change = {}

    for key, val in iteritems(desired):
        if key not in current:
            # Supported keys are listed in the documentation
            # and must be determined in the get_resource_limits function
            # (follow 'AS' keyword)
            module.fail_json(msg="resource_limits: key '%s' is unsupported." % key)

        try:
            val = int(val)
        except Exception:
            module.fail_json(msg="Can't convert value '%s' to integer." % val)

        if val != current.get(key):
            needs_to_change[key] = val

    return needs_to_change


def limit_resources(module, cursor, user, host, resource_limits, check_mode):
    """Limit user resources.

    Args:
        module (AnsibleModule): Ansible module object.
        cursor (cursor): DB driver cursor object.
        user (str): User name.
        host (str): User host name.
        resource_limit (dict): Dictionary with desired limits.
        check_mode (bool): Run the function in check mode or not.

    Returns: True, if changed, False otherwise.
    """
    if not server_supports_alter_user(cursor):
        module.fail_json(msg="The server version does not match the requirements "
                             "for resource_limits parameter. See module's documentation.")

    current_limits = get_resource_limits(cursor, user, host)

    needs_to_change = match_resource_limits(module, current_limits, resource_limits)

    if not needs_to_change:
        return False

    if needs_to_change and check_mode:
        return True

    # If not check_mode
    tmp = []
    for key, val in iteritems(needs_to_change):
        tmp.append('%s %s' % (key, val))

    query = "ALTER USER %s@%s"
    query += ' WITH %s' % ' '.join(tmp)
    cursor.execute(query, (user, host))
    return True


def get_impl(cursor):
    global impl
    cursor.execute("SELECT VERSION()")
    if 'mariadb' in cursor.fetchone()[0].lower():
        from ansible_collections.community.mysql.plugins.module_utils.implementations.mariadb import user as mariauser
        impl = mariauser
    else:
        from ansible_collections.community.mysql.plugins.module_utils.implementations.mysql import user as mysqluser
        impl = mysqluser