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# Resolver

The tool to check the availability or syntax of domain, IP or URL.

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Provides a way to provides the nameserver to use.

Author: Nissar Chababy, @funilrys, contactTATAfunilrysTODTODcom

Special thanks: https://pyfunceble.github.io/#/special-thanks

Contributors: https://pyfunceble.github.io/#/contributors

Project link: https://github.com/funilrys/PyFunceble

Project documentation: https://docs.pyfunceble.com

Project homepage: https://pyfunceble.github.io/

License: ::

    Copyright 2017, 2018, 2019, 2020, 2022, 2023, 2024 Nissar Chababy

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        https://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.

## `Resolver`

Provides the right resolver.

Parameters:

Name | Type | Description | Default
--- | --- | --- | ---
`nameservers` | `Optional[List[str]]` | The list of nameservers to communicate with. | `None`

Source code in `PyFunceble/query/dns/resolver.py`

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    class Resolver:
        """
        Provides the right resolver.

        :param nameservers:
            The list of nameservers to communicate with.
        """

        STD_TIMEOUT: float = 5.0

        timeout: float = 3.0

        nameservers: Nameservers = Nameservers()
        internal_resolver: Optional[dns.resolver.Resolver] = None

        def __init__(
            self, nameservers: Optional[List[str]] = None, timeout: Optional[float] = None
        ) -> None:
            if nameservers is not None:
                self.set_nameservers(nameservers)
            else:
                self.nameservers.guess_and_set_nameservers()

            if timeout is not None:
                self.set_timeout(timeout)
            else:
                self.guess_and_set_timeout()

        def configure_resolver(func):  # pylint: disable=no-self-argument
            """
            Configures the resolvers after calling the decorated method.
            """

            @functools.wraps(func)
            def wrapper(self, *args, **kwargs):
                result = func(self, *args, **kwargs)  # pylint: disable=not-callable

                self.internal_resolver.lifetime = self.timeout + 2.0
                self.internal_resolver.timeout = self.timeout
                self.internal_resolver.nameservers = self.nameservers.get_nameservers()
                self.internal_resolver.nameserver_ports = (
                    self.nameservers.get_nameserver_ports()
                )

                return result

            return wrapper

        def set_nameservers(self, value: List[str]) -> "Resolver":
            """
            Sets the given nameserver.
            """

            self.nameservers.set_nameservers(value)

        def set_timeout(self, value: Union[float, int]) -> "Resolver":
            """
            Sets the timeout of a query.
            """

            if not isinstance(value, (float, int)):
                raise TypeError(f"<value> should be {float}, {type(value)} given.")

            self.timeout = float(value)

            return self

        def get_nameservers(self) -> Optional[List[str]]:
            """
            Provides the currently set list of nameserver.
            """

            return self.nameservers.get_nameservers()

        def get_nameserver_ports(self) -> Optional[dict]:
            """
            Provides the currently set list of nameserver ports.
            """

            return self.nameservers.get_nameserver_ports()

        def get_timeout(self) -> Optional[float]:
            """
            Provides the currently set query timeout.
            """

            return self.timeout

        def guess_and_set_timeout(self) -> "Resolver":
            """
            Tries to guess the the timeout from the configuration.
            """

            if PyFunceble.facility.ConfigLoader.is_already_loaded():
                self.set_timeout(float(PyFunceble.storage.CONFIGURATION.lookup.timeout))
            else:
                self.set_timeout(self.STD_TIMEOUT)

            return self

        def guess_all_settings(
            self,
        ) -> "Resolver":  # pragma: no cover ## Method themselves are more important
            """
            Try to guess all settings.
            """

            to_ignore = ["guess_all_settings"]

            for method in dir(self):
                if method in to_ignore or not method.startswith("guess_"):
                    continue

                getattr(self, method)()

            return self

        @configure_resolver
        def get_resolver(self) -> dns.resolver.Resolver:
            """
            Provides the resolver to work with.
            """

            if self.internal_resolver:
                return self.internal_resolver

            if self.nameservers.get_nameservers():
                self.internal_resolver = dns.resolver.Resolver(configure=False)
            else:  # pragma: no cover ## I don't want to play with the default resolver.
                self.internal_resolver = dns.resolver.Resolver()

            return self.internal_resolver

### `configure_resolver(func)`

Configures the resolvers after calling the decorated method.

Source code in `PyFunceble/query/dns/resolver.py`

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    def configure_resolver(func):  # pylint: disable=no-self-argument
        """
        Configures the resolvers after calling the decorated method.
        """

        @functools.wraps(func)
        def wrapper(self, *args, **kwargs):
            result = func(self, *args, **kwargs)  # pylint: disable=not-callable

            self.internal_resolver.lifetime = self.timeout + 2.0
            self.internal_resolver.timeout = self.timeout
            self.internal_resolver.nameservers = self.nameservers.get_nameservers()
            self.internal_resolver.nameserver_ports = (
                self.nameservers.get_nameserver_ports()
            )

            return result

        return wrapper

### `get_nameserver_ports()`

Provides the currently set list of nameserver ports.

Source code in `PyFunceble/query/dns/resolver.py`

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    def get_nameserver_ports(self) -> Optional[dict]:
        """
        Provides the currently set list of nameserver ports.
        """

        return self.nameservers.get_nameserver_ports()

### `get_nameservers()`

Provides the currently set list of nameserver.

Source code in `PyFunceble/query/dns/resolver.py`

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    def get_nameservers(self) -> Optional[List[str]]:
        """
        Provides the currently set list of nameserver.
        """

        return self.nameservers.get_nameservers()

### `get_resolver()`

Provides the resolver to work with.

Source code in `PyFunceble/query/dns/resolver.py`

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    @configure_resolver
    def get_resolver(self) -> dns.resolver.Resolver:
        """
        Provides the resolver to work with.
        """

        if self.internal_resolver:
            return self.internal_resolver

        if self.nameservers.get_nameservers():
            self.internal_resolver = dns.resolver.Resolver(configure=False)
        else:  # pragma: no cover ## I don't want to play with the default resolver.
            self.internal_resolver = dns.resolver.Resolver()

        return self.internal_resolver

### `get_timeout()`

Provides the currently set query timeout.

Source code in `PyFunceble/query/dns/resolver.py`

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    def get_timeout(self) -> Optional[float]:
        """
        Provides the currently set query timeout.
        """

        return self.timeout

### `guess_all_settings()`

Try to guess all settings.

Source code in `PyFunceble/query/dns/resolver.py`

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    def guess_all_settings(
        self,
    ) -> "Resolver":  # pragma: no cover ## Method themselves are more important
        """
        Try to guess all settings.
        """

        to_ignore = ["guess_all_settings"]

        for method in dir(self):
            if method in to_ignore or not method.startswith("guess_"):
                continue

            getattr(self, method)()

        return self

### `guess_and_set_timeout()`

Tries to guess the the timeout from the configuration.

Source code in `PyFunceble/query/dns/resolver.py`

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    def guess_and_set_timeout(self) -> "Resolver":
        """
        Tries to guess the the timeout from the configuration.
        """

        if PyFunceble.facility.ConfigLoader.is_already_loaded():
            self.set_timeout(float(PyFunceble.storage.CONFIGURATION.lookup.timeout))
        else:
            self.set_timeout(self.STD_TIMEOUT)

        return self

### `set_nameservers(value)`

Sets the given nameserver.

Source code in `PyFunceble/query/dns/resolver.py`

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    def set_nameservers(self, value: List[str]) -> "Resolver":
        """
        Sets the given nameserver.
        """

        self.nameservers.set_nameservers(value)

### `set_timeout(value)`

Sets the timeout of a query.

Source code in `PyFunceble/query/dns/resolver.py`

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    def set_timeout(self, value: Union[float, int]) -> "Resolver":
        """
        Sets the timeout of a query.
        """

        if not isinstance(value, (float, int)):
            raise TypeError(f"<value> should be {float}, {type(value)} given.")

        self.timeout = float(value)

        return self