tests/test_derivepassphrase_ssh_agent/test_000_basic.py (eec18c8) - derivepassphrase.git

test_000_basic.py

# SPDX-FileCopyrightText: 2025 Marco Ricci <software@the13thletter.info>
#
# SPDX-License-Identifier: Zlib

"""Test OpenSSH key loading and signing."""

from __future__ import annotations

import base64
import contextlib
import errno
import importlib.metadata
import io
import os
import pathlib
import re
import socket
import sys
import types
from typing import TYPE_CHECKING, NamedTuple

import click
import hypothesis
import pytest
from hypothesis import strategies
from typing_extensions import TypeAlias

from derivepassphrase import _types, ssh_agent, vault
from derivepassphrase._internals import cli_helpers
from derivepassphrase.ssh_agent import socketprovider
from tests import data, machinery
from tests.data import callables
from tests.machinery import pytest as pytest_machinery

if TYPE_CHECKING:
    from collections.abc import Iterable, Iterator, Mapping

from typing_extensions import Any, Buffer, Literal

if sys.version_info < (3, 11):
    from exceptiongroup import ExceptionGroup

class Parametrize(types.SimpleNamespace):
    BAD_ENTRY_POINTS = pytest.mark.parametrize(
        "additional_entry_points",
        [
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.faulty_entry_callable.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: faulty_entry_callable",
                    ),
                ],
                id="not-callable",
            ),
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.faulty_entry_name_exists.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: faulty_entry_name_exists",
                    ),
                ],
                id="name-already-exists",
            ),
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.faulty_entry_alias_exists.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: faulty_entry_alias_exists",
                    ),
                ],
                id="alias-already-exists",
            ),
        ],
    )
    GOOD_ENTRY_POINTS = pytest.mark.parametrize(
        "additional_entry_points",
        [
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.posix_entry.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: posix_entry",
                    ),
                    importlib.metadata.EntryPoint(
                        name=data.the_annoying_os_entry.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: the_annoying_os_entry",
                    ),
                ],
                id="existing-entries",
            ),
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=callables.provider_entry1.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data.callables: provider_entry1",
                    ),
                    importlib.metadata.EntryPoint(
                        name=callables.provider_entry2.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data.callables: provider_entry2",
                    ),
                ],
                id="new-entries",
            ),
        ],
    )
    STUBBED_AGENT_ADDRESSES = pytest.mark.parametrize(
        ["address", "exception", "match"],
        [
            pytest.param(None, KeyError, "SSH_AUTH_SOCK", id="unset"),
            pytest.param("stub-ssh-agent:", None, "", id="standard"),
            pytest.param(
                str(pathlib.Path("~").expanduser()),
                FileNotFoundError,
                os.strerror(errno.ENOENT),
                id="invalid-url",
            ),
            pytest.param(
                "stub-ssh-agent:EPROTONOSUPPORT",
                OSError,
                os.strerror(errno.EPROTONOSUPPORT),
                id="protocol-not-supported",
            ),
            pytest.param(
                "stub-ssh-agent:ABCDEFGHIJKLMNOPQRSTUVWXYZ",
                OSError,
                os.strerror(errno.EINVAL),
                id="invalid-error-code",
            ),
        ],
    )
    EXISTING_REGISTRY_ENTRIES = pytest.mark.parametrize(
        "existing", ["posix", "the_annoying_os"]
    )
    SSH_STRING_EXCEPTIONS = pytest.mark.parametrize(
        ["input", "exc_type", "exc_pattern"],
        [
            pytest.param(
                "some string", TypeError, "invalid payload type", id="str"
            ),
        ],
    )
    UINT32_EXCEPTIONS = pytest.mark.parametrize(
        ["input", "exc_type", "exc_pattern"],
        [
            pytest.param(
                10000000000000000,
                OverflowError,
                "int too big to convert",
                id="10000000000000000",
            ),
            pytest.param(
                -1,
                OverflowError,
                "can't convert negative int to unsigned",
                id="-1",
            ),
        ],
    )
    SSH_UNSTRING_EXCEPTIONS = pytest.mark.parametrize(
        ["input", "exc_type", "exc_pattern", "has_trailer", "parts"],
        [
            pytest.param(
                b"ssh",
                ValueError,
                "malformed SSH byte string",
                False,
                None,
                id="unencoded",
            ),
            pytest.param(
                b"\x00\x00\x00\x08ssh-rsa",
                ValueError,
                "malformed SSH byte string",
                False,
                None,
                id="truncated",
            ),
            pytest.param(
                b"\x00\x00\x00\x04XXX trailing text",
                ValueError,
                "malformed SSH byte string",
                True,
                (b"XXX ", b"trailing text"),
                id="trailing-data",
            ),
        ],
    )
    SSH_STRING_INPUT = pytest.mark.parametrize(
        ["input", "expected"],
        [
            pytest.param(
                b"ssh-rsa",
                b"\x00\x00\x00\x07ssh-rsa",
                id="ssh-rsa",
            ),
            pytest.param(
                b"ssh-ed25519",
                b"\x00\x00\x00\x0bssh-ed25519",
                id="ssh-ed25519",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(b"ssh-ed25519"),
                b"\x00\x00\x00\x0f\x00\x00\x00\x0bssh-ed25519",
                id="string(ssh-ed25519)",
            ),
        ],
    )
    SSH_UNSTRING_INPUT = pytest.mark.parametrize(
        ["input", "expected"],
        [
            pytest.param(
                b"\x00\x00\x00\x07ssh-rsa",
                b"ssh-rsa",
                id="ssh-rsa",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(b"ssh-ed25519"),
                b"ssh-ed25519",
                id="ssh-ed25519",
            ),
        ],
    )
    UINT32_INPUT = pytest.mark.parametrize(
        ["input", "expected"],
        [
            pytest.param(16777216, b"\x01\x00\x00\x00", id="16777216"),
        ],
    )
    SIGN_ERROR_RESPONSES = pytest.mark.parametrize(
        [
            "key",
            "check",
            "response_code",
            "response",
            "exc_type",
            "exc_pattern",
        ],
        [
            pytest.param(
                b"invalid-key",
                True,
                _types.SSH_AGENT.FAILURE,
                b"",
                KeyError,
                "target SSH key not loaded into agent",
                id="key-not-loaded",
            ),
            pytest.param(
                data.SUPPORTED_KEYS["ed25519"].public_key_data,
                True,
                _types.SSH_AGENT.FAILURE,
                b"",
                ssh_agent.SSHAgentFailedError,
                "failed to complete the request",
                id="failed-to-complete",
            ),
        ],
    )
    SSH_KEY_SELECTION = pytest.mark.parametrize(
        ["key", "single"],
        [
            (value.public_key_data, False)
            for value in data.SUPPORTED_KEYS.values()
        ]
        + [(callables.list_keys_singleton()[0].key, True)],
        ids=[*data.SUPPORTED_KEYS.keys(), "singleton"],
    )
    SH_EXPORT_LINES = pytest.mark.parametrize(
        ["line", "env_name", "value"],
        [
            pytest.param(
                "SSH_AUTH_SOCK=/tmp/pageant.user/pageant.27170; export SSH_AUTH_SOCK;",
                "SSH_AUTH_SOCK",
                "/tmp/pageant.user/pageant.27170",
                id="value-export-semicolon-pageant",
            ),
            pytest.param(
                "SSH_AUTH_SOCK=/tmp/ssh-3CSTC1W5M22A/agent.27270; export SSH_AUTH_SOCK;",
                "SSH_AUTH_SOCK",
                "/tmp/ssh-3CSTC1W5M22A/agent.27270",
                id="value-export-semicolon-openssh",
            ),
            pytest.param(
                "SSH_AUTH_SOCK=/tmp/pageant.user/pageant.27170; export SSH_AUTH_SOCK",
                "SSH_AUTH_SOCK",
                "/tmp/pageant.user/pageant.27170",
                id="value-export-pageant",
            ),
            pytest.param(
                "export SSH_AUTH_SOCK=/tmp/ssh-3CSTC1W5M22A/agent.27270;",
                "SSH_AUTH_SOCK",
                "/tmp/ssh-3CSTC1W5M22A/agent.27270",
                id="export-value-semicolon-openssh",
            ),
            pytest.param(
                "export SSH_AUTH_SOCK=/tmp/pageant.user/pageant.27170",
                "SSH_AUTH_SOCK",
                "/tmp/pageant.user/pageant.27170",
                id="export-value-pageant",
            ),
            pytest.param(
                "SSH_AGENT_PID=27170; export SSH_AGENT_PID;",
                "SSH_AGENT_PID",
                "27170",
                id="pid-export-semicolon",
            ),
            pytest.param(
                "SSH_AGENT_PID=27170; export SSH_AGENT_PID",
                "SSH_AGENT_PID",
                "27170",
                id="pid-export",
            ),
            pytest.param(
                "export SSH_AGENT_PID=27170;",
                "SSH_AGENT_PID",
                "27170",
                id="export-pid-semicolon",
            ),
            pytest.param(
                "export SSH_AGENT_PID=27170",
                "SSH_AGENT_PID",
                "27170",
                id="export-pid",
            ),
            pytest.param(
                "export VARIABLE=value; export OTHER_VARIABLE=other_value;",
                "VARIABLE",
                None,
                id="export-too-much",
            ),
            pytest.param(
                "VARIABLE=value",
                "VARIABLE",
                None,
                id="no-export",
            ),
        ],
    )
    INVALID_SSH_AGENT_MESSAGES = pytest.mark.parametrize(
        "message",
        [
            pytest.param(b"\x00\x00\x00\x00", id="empty-message"),
            pytest.param(b"\x00\x00\x00\x0f\x0d", id="truncated-message"),
            pytest.param(
                b"\x00\x00\x00\x06\x1b\x00\x00\x00\x01\xff",
                id="invalid-extension-name",
            ),
            pytest.param(
                b"\x00\x00\x00\x11\x0d\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
                id="sign-with-trailing-data",
            ),
        ],
    )
    UNSUPPORTED_SSH_AGENT_MESSAGES = pytest.mark.parametrize(
        "message",
        [
            pytest.param(
                ssh_agent.SSHAgentClient.string(
                    b"".join([
                        b"\x0d",
                        ssh_agent.SSHAgentClient.string(
                            data.ALL_KEYS["rsa"].public_key_data
                        ),
                        ssh_agent.SSHAgentClient.string(vault.Vault.UUID),
                        b"\x00\x00\x00\x02",
                    ])
                ),
                id="sign-with-flags",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(
                    b"".join([
                        b"\x0d",
                        ssh_agent.SSHAgentClient.string(
                            data.ALL_KEYS["ed25519"].public_key_data
                        ),
                        b"\x00\x00\x00\x08\x00\x01\x02\x03\x04\x05\x06\x07",
                        b"\x00\x00\x00\x00",
                    ])
                ),
                id="sign-with-nonstandard-passphrase",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(
                    b"".join([
                        b"\x0d",
                        ssh_agent.SSHAgentClient.string(
                            data.ALL_KEYS["dsa1024"].public_key_data
                        ),
                        ssh_agent.SSHAgentClient.string(vault.Vault.UUID),
                        b"\x00\x00\x00\x00",
                    ])
                ),
                id="sign-key-no-expected-signature",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(
                    b"".join([
                        b"\x0d",
                        b"\x00\x00\x00\x00",
                        ssh_agent.SSHAgentClient.string(vault.Vault.UUID),
                        b"\x00\x00\x00\x00",
                    ])
                ),
                id="sign-key-unregistered-test-key",
            ),
        ],
    )
    PUBLIC_KEY_DATA = pytest.mark.parametrize(
        "public_key_struct",
        list(data.SUPPORTED_KEYS.values()),
        ids=list(data.SUPPORTED_KEYS.keys()),
    )
    REQUEST_ERROR_RESPONSES = pytest.mark.parametrize(
        ["request_code", "response_code", "exc_type", "exc_pattern"],
        [
            pytest.param(
                _types.SSH_AGENTC.REQUEST_IDENTITIES,
                _types.SSH_AGENT.SUCCESS,
                ssh_agent.SSHAgentFailedError,
                re.escape(
                    f"[Code {_types.SSH_AGENT.IDENTITIES_ANSWER.value}]"
                ),
                id="REQUEST_IDENTITIES-expect-SUCCESS",
            ),
        ],
    )
    TRUNCATED_AGENT_RESPONSES = pytest.mark.parametrize(
        "response",
        [
            b"\x00\x00",
            b"\x00\x00\x00\x1f some bytes missing",
        ],
        ids=["in-header", "in-body"],
    )
    LIST_KEYS_ERROR_RESPONSES = pytest.mark.parametrize(
        ["response_code", "response", "exc_type", "exc_pattern"],
        [
            pytest.param(
                _types.SSH_AGENT.FAILURE,
                b"",
                ssh_agent.SSHAgentFailedError,
                "failed to complete the request",
                id="failed-to-complete",
            ),
            pytest.param(
                _types.SSH_AGENT.IDENTITIES_ANSWER,
                b"\x00\x00\x00\x01",
                EOFError,
                "truncated response",
                id="truncated-response",
            ),
            pytest.param(
                _types.SSH_AGENT.IDENTITIES_ANSWER,
                b"\x00\x00\x00\x00abc",
                ssh_agent.TrailingDataError,
                "Overlong response",
                id="overlong-response",
            ),
        ],
    )
    QUERY_EXTENSIONS_MALFORMED_RESPONSES = pytest.mark.parametrize(
        "response_data",
        [
            pytest.param(b"\xde\xad\xbe\xef", id="truncated"),
            pytest.param(
                b"\x00\x00\x00\x0fwrong extension", id="wrong-extension"
            ),
            pytest.param(
                b"\x00\x00\x00\x05query\xde\xad\xbe\xef", id="with-trailer"
            ),
            pytest.param(
                b"\x00\x00\x00\x05query\x00\x00\x00\x04ext1\x00\x00",
                id="with-extra-fields",
            ),
        ],
    )
    SUPPORTED_SSH_TEST_KEYS = pytest.mark.parametrize(
        ["ssh_test_key_type", "ssh_test_key"],
        list(data.SUPPORTED_KEYS.items()),
        ids=data.SUPPORTED_KEYS.keys(),
    )
    ALL_SSH_TEST_KEYS = pytest.mark.parametrize(
        ["ssh_test_key_type", "ssh_test_key"],
        list(data.ALL_KEYS.items()),
        ids=data.ALL_KEYS.keys(),
    )
    RESOLVE_CHAINS = pytest.mark.parametrize(
        ["terminal", "chain"],
        [
            pytest.param("callable", ["a"], id="callable-1"),
            pytest.param("callable", ["a", "b", "c", "d"], id="callable-4"),
            pytest.param("alias", ["e"], id="alias-1"),
            pytest.param("alias", ["e", "f", "g", "h", "i"], id="alias-5"),
            pytest.param("unimplemented", ["j"], id="unimplemented-1"),
            pytest.param("unimplemented", ["j", "k"], id="unimplemented-2"),
        ],
    )

class TestStubbedSSHAgentSocketRequests:
    """Test the stubbed SSH agent socket: normal requests."""

@contextlib.contextmanager
    def _get_addressed_agent(
        self, *, extended_agent: bool = False
    ) -> Iterator[machinery.StubbedSSHAgentSocketWithAddress]:
        agent_class: type[machinery.StubbedSSHAgentSocketWithAddress] = (
            machinery.StubbedSSHAgentSocketWithAddressAndDeterministicDSA
            if extended_agent
            else machinery.StubbedSSHAgentSocketWithAddress
        )
        with contextlib.ExitStack() as stack:
            monkeypatch = stack.enter_context(pytest.MonkeyPatch.context())
            monkeypatch.setenv("SSH_AUTH_SOCK", agent_class.ADDRESS)
            agent = stack.enter_context(agent_class())
            yield agent

def test_query_extensions_base(self) -> None:
        """The base agent implements no extensions."""
        with self._get_addressed_agent(extended_agent=False) as agent:
            assert "query" not in agent.enabled_extensions
            query_request = (
                # SSH string header
                b"\x00\x00\x00\x0a"
                # request code: SSH_AGENTC_EXTENSION
                b"\x1b"
                # payload: SSH string "query"
                b"\x00\x00\x00\x05query"
            )
            query_response = (
                # SSH string header
                b"\x00\x00\x00\x01"
                # response code: SSH_AGENT_FAILURE
                b"\x05"
            )
            agent.sendall(query_request)
            assert agent.recv(1000) == query_response

def test_query_extensions_extended(self) -> None:
        """The extended agent implements a known list of extensions."""
        with self._get_addressed_agent(extended_agent=True) as agent:
            assert "query" in agent.enabled_extensions
            query_request = (
                # SSH string header
                b"\x00\x00\x00\x0a"
                # request code: SSH_AGENTC_EXTENSION
                b"\x1b"
                # payload: SSH string "query"
                b"\x00\x00\x00\x05query"
            )
            query_response = (
                # SSH string header
                b"\x00\x00\x00\x40"
                # response code: SSH_AGENT_EXTENSION_RESPONSE
                b"\x1d"
                # extension response: extension type ("query")
                b"\x00\x00\x00\x05query"
                # supported extension #1: query
                b"\x00\x00\x00\x05query"
                # supported extension #2:
                # list-extended@putty.projects.tartarus.org
                b"\x00\x00\x00\x29list-extended@putty.projects.tartarus.org"
            )
            agent.sendall(query_request)
            assert agent.recv(1000) == query_response

def test_request_identities(self) -> None:
        """The agent implements a known list of identities."""
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        with machinery.StubbedSSHAgentSocket() as agent:
            query_request = (
                # SSH string header
                b"\x00\x00\x00\x01"
                # request code: SSH_AGENTC_REQUEST_IDENTITIES
                b"\x0b"
            )
            agent.sendall(query_request)
            message_length = int.from_bytes(agent.recv(4), "big")
            orig_message: bytes | bytearray = bytearray(
                agent.recv(message_length)
            )
            assert (
                _types.SSH_AGENT(orig_message[0])
                == _types.SSH_AGENT.IDENTITIES_ANSWER
            )
            identity_count = int.from_bytes(orig_message[1:5], "big")
            message = bytes(orig_message[5:])
            for _ in range(identity_count):
                key, message = unstring_prefix(message)
                _comment, message = unstring_prefix(message)
                assert key
                assert key in {
                    k.public_key_data for k in data.ALL_KEYS.values()
                }
            assert not message

def test_request_identities_extended(self) -> None:
        """The extended agent implements PuTTY's `list-extended` extension."""
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        with self._get_addressed_agent(extended_agent=True) as agent:
            extension_request = (
                # SSH string header
                b"\x00\x00\x00\x2e"
                # request code: SSH_AGENTC_REQUEST_IDENTITIES
                b"\x1b"
                # extension type: list-extended@putty.projects.tartarus.org
                b"\x00\x00\x00\x29list-extended@putty.projects.tartarus.org"
                # (no payload)
            )
            agent.sendall(extension_request)
            message_length = int.from_bytes(agent.recv(4), "big")
            orig_message: bytes | bytearray = bytearray(
                agent.recv(message_length)
            )
            assert (
                _types.SSH_AGENT(orig_message[0]) == _types.SSH_AGENT.SUCCESS
            )
            identity_count = int.from_bytes(orig_message[1:5], "big")
            message = bytes(orig_message[5:])
            for _ in range(identity_count):
                key, message = unstring_prefix(message)
                _comment, message = unstring_prefix(message)
                flags, message = unstring_prefix(message)
                assert flags == b"\x00\x00\x00\x00"
                assert key
                assert key in {
                    k.public_key_data for k in data.ALL_KEYS.values()
                }
            assert not message

@Parametrize.SUPPORTED_SSH_TEST_KEYS
    def test_sign(
        self,
        ssh_test_key_type: str,
        ssh_test_key: data.SSHTestKey,
    ) -> None:
        """The agent signs known key/message pairs."""
        del ssh_test_key_type
        spec = data.SSHTestKeyDeterministicSignatureClass.SPEC
        assert ssh_test_key.expected_signatures[spec].signature is not None
        string = ssh_agent.SSHAgentClient.string
        query_request = string(
            # request code: SSH_AGENTC_SIGN_REQUEST
            b"\x0d"
            # key: SSH string of the public key
            + string(ssh_test_key.public_key_data)
            # payload: SSH string of the vault UUID
            + string(vault.Vault.UUID)
            # signing flags (uint32, empty)
            + b"\x00\x00\x00\x00"
        )
        query_response = string(
            # response code: SSH_AGENT_SIGN_RESPONSE
            b"\x0e"
            # expected payload: the binary signature as recorded in the test key data structure
            + string(ssh_test_key.expected_signatures[spec].signature)
        )
        with machinery.StubbedSSHAgentSocket() as agent:
            agent.sendall(query_request)
            assert agent.recv(1000) == query_response

class TestStubbedSSHAgentSocketProperOperations:
    """Test the stubbed SSH agent socket: proper use and misuse."""

def test_close_multiple(self) -> None:
        """The agent can be closed repeatedly."""
        with machinery.StubbedSSHAgentSocket() as agent:
            pass
        with machinery.StubbedSSHAgentSocket() as agent:
            pass
        del agent

def test_closed_agents_cannot_be_interacted_with(self) -> None:
        """The agent can be closed repeatedly."""
        with machinery.StubbedSSHAgentSocket() as agent:
            pass
        query_request = (
            # SSH string header
            b"\x00\x00\x00\x0a"
            # request code: SSH_AGENTC_EXTENSION
            b"\x1b"
            # payload: SSH string "query"
            b"\x00\x00\x00\x05query"
        )
        query_response = b""
        with pytest.raises(
            ValueError,
            match=re.escape(machinery.StubbedSSHAgentSocket._SOCKET_IS_CLOSED),
        ):
            agent.sendall(query_request)
        assert agent.recv(100) == query_response

def test_no_recv_without_sendall(self) -> None:
        """The agent requires a message before sending a response."""
        with machinery.StubbedSSHAgentSocket() as agent:  # noqa: SIM117
            with pytest.raises(
                AssertionError,
                match=re.escape(
                    machinery.StubbedSSHAgentSocket._PROTOCOL_VIOLATION
                ),
            ):
                agent.recv(100)

@Parametrize.INVALID_SSH_AGENT_MESSAGES
    def test_invalid_ssh_agent_messages(
        self,
        message: Buffer,
    ) -> None:
        """The agent responds with errors on invalid messages."""
        query_response = (
            # SSH string header
            b"\x00\x00\x00\x01"
            # response code: SSH_AGENT_FAILURE
            b"\x05"
        )
        with machinery.StubbedSSHAgentSocket() as agent:
            agent.sendall(message)
            assert agent.recv(100) == query_response

class TestStubbedSSHAgentSocketSupportedAndUnsupportedFeatures:
    """Test the stubbed SSH agent socket: supported/unsupported features."""

@Parametrize.UNSUPPORTED_SSH_AGENT_MESSAGES
    def test_unsupported_ssh_agent_messages(
        self,
        message: Buffer,
    ) -> None:
        """The agent responds with errors on unsupported messages."""
        query_response = (
            # SSH string header
            b"\x00\x00\x00\x01"
            # response code: SSH_AGENT_FAILURE
            b"\x05"
        )
        with machinery.StubbedSSHAgentSocket() as agent:
            agent.sendall(message)
            assert agent.recv(100) == query_response

@Parametrize.STUBBED_AGENT_ADDRESSES
    def test_addresses(
        self,
        address: str | None,
        exception: type[Exception] | None,
        match: str,
    ) -> None:
        """The agent accepts addresses."""
        with contextlib.ExitStack() as stack:
            monkeypatch = stack.enter_context(pytest.MonkeyPatch.context())
            if address:
                monkeypatch.setenv("SSH_AUTH_SOCK", address)
            else:
                monkeypatch.delenv("SSH_AUTH_SOCK", raising=False)
            if exception:
                stack.enter_context(
                    pytest.raises(exception, match=re.escape(match))
                )
            machinery.StubbedSSHAgentSocketWithAddress()

class TestStaticFunctionality:
    """Test the static functionality of the `ssh_agent` module."""

@staticmethod
    def as_ssh_string(bytestring: bytes) -> bytes:
        """Return an encoded SSH string from a bytestring.

This is a helper function for hypothesis data generation.

"""
        return int.to_bytes(len(bytestring), 4, "big") + bytestring

@staticmethod
    def canonicalize1(data: bytes) -> bytes:
        """Return an encoded SSH string from a bytestring.

This is a helper function for hypothesis testing.

References:

* [David R. MacIver: Another invariant to test for
            encoders][DECODE_ENCODE]

[DECODE_ENCODE]: https://hypothesis.works/articles/canonical-serialization/

"""
        return ssh_agent.SSHAgentClient.string(
            ssh_agent.SSHAgentClient.unstring(data)
        )

@staticmethod
    def canonicalize2(data: bytes) -> bytes:
        """Return an encoded SSH string from a bytestring.

This is a helper function for hypothesis testing.

References:

* [David R. MacIver: Another invariant to test for
            encoders][DECODE_ENCODE]

[DECODE_ENCODE]: https://hypothesis.works/articles/canonical-serialization/

"""
        unstringed, trailer = ssh_agent.SSHAgentClient.unstring_prefix(data)
        assert not trailer
        return ssh_agent.SSHAgentClient.string(unstringed)

class TestShellExportScriptParsing:
    """Test the shell export script parsing utility function."""

@Parametrize.SH_EXPORT_LINES
    def test_sh_export_line_parsing(
        self, line: str, env_name: str, value: str | None
    ) -> None:
        """[`tests.data.callables.parse_sh_export_line`][] works."""
        if value is not None:
            assert (
                callables.parse_sh_export_line(line, env_name=env_name)
                == value
            )
        else:
            with pytest.raises(ValueError, match="Cannot parse sh line:"):
                callables.parse_sh_export_line(line, env_name=env_name)

class TestGracefulFailureForSSHAuthSock:
    """Test the `posix` socket provider if `SSH_AUTH_SOCK` is unset."""

def test_constructor_posix_no_ssh_auth_sock(
        self,
        skip_if_no_af_unix_support: None,
    ) -> None:
        """Abort if the running agent cannot be located on POSIX."""
        del skip_if_no_af_unix_support
        posix_handler = socketprovider.SocketProvider.resolve("posix")
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.delenv("SSH_AUTH_SOCK", raising=False)
            with pytest.raises(
                KeyError, match="SSH_AUTH_SOCK environment variable"
            ):
                posix_handler()

class TestSSHProtocolDatatypes(TestStaticFunctionality):
    """Tests for the utility functions for the SSH protocol datatypes."""

@Parametrize.UINT32_INPUT
    def test_uint32(self, input: int, expected: bytes | bytearray) -> None:
        """`uint32` encoding works."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        assert uint32(input) == expected

@hypothesis.given(strategies.integers(min_value=0, max_value=0xFFFFFFFF))
    @hypothesis.example(0xDEADBEEF).via("manual, pre-hypothesis example")
    def test_uint32_from_number(self, num: int) -> None:
        """`uint32` encoding works, starting from numbers."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        assert int.from_bytes(uint32(num), "big", signed=False) == num

@hypothesis.given(strategies.binary(min_size=4, max_size=4))
    @hypothesis.example(b"\xde\xad\xbe\xef").via(
        "manual, pre-hypothesis example"
    )
    def test_uint32_from_bytestring(self, bytestring: bytes) -> None:
        """`uint32` encoding works, starting from length four byte strings."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        assert (
            uint32(int.from_bytes(bytestring, "big", signed=False))
            == bytestring
        )

@Parametrize.SSH_STRING_INPUT
    def test_string(
        self, input: bytes | bytearray, expected: bytes | bytearray
    ) -> None:
        """SSH string encoding works."""
        string = ssh_agent.SSHAgentClient.string
        assert bytes(string(input)) == expected

@hypothesis.given(strategies.binary(max_size=0x0001FFFF))
    @hypothesis.example(b"DEADBEEF" * 10000).via(
        "manual, pre-hypothesis example with highest order bit set"
    )
    def test_string_from_bytestring(self, bytestring: bytes) -> None:
        """SSH string encoding works, starting from a byte string."""
        res = ssh_agent.SSHAgentClient.string(bytestring)
        assert res.startswith((b"\x00\x00", b"\x00\x01"))
        assert int.from_bytes(res[:4], "big", signed=False) == len(bytestring)
        assert res[4:] == bytestring

@Parametrize.SSH_UNSTRING_INPUT
    def test_unstring(
        self, input: bytes | bytearray, expected: bytes | bytearray
    ) -> None:
        """SSH string decoding works."""
        unstring = ssh_agent.SSHAgentClient.unstring
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        assert bytes(unstring(input)) == expected
        assert tuple(bytes(x) for x in unstring_prefix(input)) == (
            expected,
            b"",
        )

@hypothesis.given(strategies.binary(max_size=0x00FFFFFF))
    @hypothesis.example(b"\x00\x00\x00\x07ssh-rsa").via(
        "manual, pre-hypothesis example to attempt to detect double-decoding"
    )
    @hypothesis.example(b"\x00\x00\x00\x01").via(
        "detect no-op encoding via ill-formed SSH string"
    )
    def test_unstring_of_string_of_data(self, bytestring: bytes) -> None:
        """SSH string decoding of encoded SSH strings works.

References:

* [David R. MacIver: The Encode/Decode invariant][ENCODE_DECODE]

[ENCODE_DECODE]: https://hypothesis.works/articles/encode-decode-invariant/

"""
        string = ssh_agent.SSHAgentClient.string
        unstring = ssh_agent.SSHAgentClient.unstring
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        encoded = string(bytestring)
        assert unstring(encoded) == bytestring
        assert unstring_prefix(encoded) == (bytestring, b"")
        trailing_data = b"  trailing data"
        encoded2 = string(bytestring) + trailing_data
        assert unstring_prefix(encoded2) == (bytestring, trailing_data)

@hypothesis.given(
        strategies.binary(max_size=0x00FFFFFF).map(
            # Scoping issues, and the fact that staticmethod objects
            # (before class finalization) are not callable, necessitate
            # wrapping this staticmethod call in a lambda.
            lambda x: TestStaticFunctionality.as_ssh_string(x)  # noqa: PLW0108
        ),
    )
    def test_string_of_unstring_of_data(self, encoded: bytes) -> None:
        """SSH string decoding of encoded SSH strings works.

References:

* [David R. MacIver: Another invariant to test for
            encoders][DECODE_ENCODE]

[DECODE_ENCODE]: https://hypothesis.works/articles/canonical-serialization/

"""
        canonical_functions = [self.canonicalize1, self.canonicalize2]
        for canon1 in canonical_functions:
            for canon2 in canonical_functions:
                assert canon1(encoded) == canon2(encoded)
                assert canon1(canon2(encoded)) == canon1(encoded)

@Parametrize.UINT32_EXCEPTIONS
    def test_uint32_exceptions(
        self, input: int, exc_type: type[Exception], exc_pattern: str
    ) -> None:
        """`uint32` encoding fails for out-of-bound values."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        with pytest.raises(exc_type, match=exc_pattern):
            uint32(input)

@Parametrize.SSH_STRING_EXCEPTIONS
    def test_string_exceptions(
        self, input: Any, exc_type: type[Exception], exc_pattern: str
    ) -> None:
        """SSH string encoding fails for non-strings."""
        string = ssh_agent.SSHAgentClient.string
        with pytest.raises(exc_type, match=exc_pattern):
            string(input)

@Parametrize.SSH_UNSTRING_EXCEPTIONS
    def test_unstring_exceptions(
        self,
        input: bytes | bytearray,
        exc_type: type[Exception],
        exc_pattern: str,
        has_trailer: bool,
        parts: tuple[bytes | bytearray, bytes | bytearray] | None,
    ) -> None:
        """SSH string decoding fails for invalid values."""
        unstring = ssh_agent.SSHAgentClient.unstring
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        with pytest.raises(exc_type, match=exc_pattern):
            unstring(input)
        if has_trailer:
            assert tuple(bytes(x) for x in unstring_prefix(input)) == parts
        else:
            with pytest.raises(exc_type, match=exc_pattern):
                unstring_prefix(input)

class TestSSHAgentSocketProviderRegistry:
    """Tests for the SSH agent socket provider registry."""

def test_resolve(
        self,
    ) -> None:
        """Resolving entries in the socket provider registry works."""
        registry = socketprovider.SocketProvider.registry
        resolve = socketprovider.SocketProvider.resolve
        lookup = socketprovider.SocketProvider.lookup
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setitem(registry, "stub_agent", None)
            assert callable(lookup("native"))
            assert callable(resolve("native"))
            assert lookup("stub_agent") is None
            with pytest.raises(NotImplementedError):
                resolve("stub_agent")

@Parametrize.RESOLVE_CHAINS
    def test_resolve_chains(
        self,
        terminal: Literal["unimplemented", "alias", "callable"],
        chain: list[str],
    ) -> None:
        """Resolving a chain of providers works."""
        registry = socketprovider.SocketProvider.registry
        resolve = socketprovider.SocketProvider.resolve
        lookup = socketprovider.SocketProvider.lookup
        try:
            implementation = resolve("native")
        except NotImplementedError:  # pragma: no cover
            pytest.fail("Native SSH agent socket provider is unavailable?!")
        # TODO(the-13th-letter): Rewrite using structural pattern matching.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        target = (
            None
            if terminal == "unimplemented"
            else "native"
            if terminal == "alias"
            else implementation
        )
        with pytest.MonkeyPatch.context() as monkeypatch:
            for link in chain:
                monkeypatch.setitem(registry, link, target)
                target = link
            for link in chain:
                assert lookup(link) == (
                    implementation if terminal != "unimplemented" else None
                )
                if terminal == "unimplemented":
                    with pytest.raises(NotImplementedError):
                        resolve(link)
                else:
                    assert resolve(link) == implementation

@hypothesis.given(
        terminal=strategies.sampled_from([
            "unimplemented",
            "alias",
            "callable",
        ]),
        chain=strategies.lists(
            strategies.sampled_from([
                "c1",
                "c2",
                "c3",
                "c4",
                "c5",
                "c6",
                "c7",
                "c8",
                "c9",
                "c10",
            ]),
            min_size=1,
            unique=True,
        ),
    )
    def test_resolve_chains2(
        self,
        terminal: Literal["unimplemented", "alias", "callable"],
        chain: list[str],
    ) -> None:
        """Resolving a chain of providers works."""
        registry = socketprovider.SocketProvider.registry
        resolve = socketprovider.SocketProvider.resolve
        lookup = socketprovider.SocketProvider.lookup
        try:
            implementation = resolve("native")
        except NotImplementedError:  # pragma: no cover
            hypothesis.note(f"{registry = }")
            pytest.fail("Native SSH agent socket provider is unavailable?!")
        # TODO(the-13th-letter): Rewrite using structural pattern matching.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        target = (
            None
            if terminal == "unimplemented"
            else "native"
            if terminal == "alias"
            else implementation
        )
        with pytest.MonkeyPatch.context() as monkeypatch:
            for link in chain:
                monkeypatch.setitem(registry, link, target)
                target = link
            for link in chain:
                assert lookup(link) == (
                    implementation if terminal != "unimplemented" else None
                )
                if terminal == "unimplemented":
                    with pytest.raises(NotImplementedError):
                        resolve(link)
                else:
                    assert resolve(link) == implementation

@Parametrize.GOOD_ENTRY_POINTS
    def test_find_all_socket_providers(
        self,
        additional_entry_points: list[importlib.metadata.EntryPoint],
    ) -> None:
        """Finding all SSH agent socket providers works."""
        resolve = socketprovider.SocketProvider.resolve
        old_registry = socketprovider.SocketProvider.registry
        with pytest_machinery.faked_entry_point_list(
            additional_entry_points, remove_conflicting_entries=False
        ) as names:
            socketprovider.SocketProvider._find_all_ssh_agent_socket_providers()
            for name in names:
                assert name in socketprovider.SocketProvider.registry
                assert resolve(name) in {
                    callables.provider_entry_provider,
                    *old_registry.values(),
                }

@Parametrize.BAD_ENTRY_POINTS
    def test_find_all_socket_providers_errors(
        self,
        additional_entry_points: list[importlib.metadata.EntryPoint],
    ) -> None:
        """Finding faulty SSH agent socket providers raises errors."""
        with contextlib.ExitStack() as stack:
            stack.enter_context(
                pytest_machinery.faked_entry_point_list(
                    additional_entry_points, remove_conflicting_entries=False
                )
            )
            stack.enter_context(pytest.raises(AssertionError))
            socketprovider.SocketProvider._find_all_ssh_agent_socket_providers()

def test_already_registered(
        self,
    ) -> None:
        """The registry forbids overwriting entries."""
        registry = socketprovider.SocketProvider.registry.copy()
        resolve = socketprovider.SocketProvider.resolve
        register = socketprovider.SocketProvider.register
        the_annoying_os = resolve("the_annoying_os")
        posix = resolve("posix")
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", registry
            )
            register("posix")(posix)
            register("the_annoying_os")(the_annoying_os)
            with pytest.raises(ValueError, match="already registered"):
                register("posix")(the_annoying_os)
            with pytest.raises(ValueError, match="already registered"):
                register("the_annoying_os")(posix)
            with pytest.raises(ValueError, match="already registered"):
                register("posix", "the_annoying_os_named_pipe")(posix)
            with pytest.raises(ValueError, match="already registered"):
                register("the_annoying_os", "unix_domain")(the_annoying_os)

def test_resolve_non_existant_entries(
        self,
    ) -> None:
        """Resolving a non-existant entry fails."""
        new_registry = {
            "posix": socketprovider.SocketProvider.registry["posix"],
            "the_annoying_os": socketprovider.SocketProvider.registry[
                "the_annoying_os"
            ],
        }
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", new_registry
            )
            with pytest.raises(socketprovider.NoSuchProviderError):
                socketprovider.SocketProvider.resolve("native")

def test_register_new_entry(
        self,
    ) -> None:
        """Registering new entries works."""

def socket_provider() -> _types.SSHAgentSocket:
            raise AssertionError

names = ["spam", "ham", "eggs", "parrot"]
        new_registry = {
            "posix": socketprovider.SocketProvider.registry["posix"],
            "the_annoying_os": socketprovider.SocketProvider.registry[
                "the_annoying_os"
            ],
        }
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", new_registry
            )
            assert not any(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert (
                socketprovider.SocketProvider.register(*names)(socket_provider)
                is socket_provider
            )
            assert all(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert all([
                socketprovider.SocketProvider.resolve(n) is socket_provider
                for n in names
            ])

@Parametrize.EXISTING_REGISTRY_ENTRIES
    def test_register_old_entry(
        self,
        existing: str,
    ) -> None:
        """Registering old entries works."""

provider = socketprovider.SocketProvider.resolve(existing)
        new_registry = {
            "posix": socketprovider.SocketProvider.registry["posix"],
            "the_annoying_os": socketprovider.SocketProvider.registry[
                "the_annoying_os"
            ],
            "unix_domain": "posix",
            "the_annoying_os_named_pipe": "the_annoying_os",
        }
        names = [
            k
            for k, v in socketprovider.SocketProvider.registry.items()
            if v == existing
        ]
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", new_registry
            )
            assert not all(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert (
                socketprovider.SocketProvider.register(existing, *names)(
                    provider
                )
                is provider
            )
            assert all(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert all([
                socketprovider.SocketProvider.resolve(n) is provider
                for n in [existing, *names]
            ])

class TestAgentSigning:
    """Test actually talking to the SSH agent: signing data."""

@Parametrize.ALL_SSH_TEST_KEYS
    def test_sign_data_via_agent(
        self,
        ssh_agent_client_with_test_keys_loaded: ssh_agent.SSHAgentClient,
        ssh_test_key_type: str,
        ssh_test_key: data.SSHTestKey,
    ) -> None:
        """Signing data with specific SSH keys works iff the key is suitable.

Single tests may abort early (skip) if the indicated key is not
        loaded in the agent.  Presumably this means the key type is
        unsupported.

"""
        client = ssh_agent_client_with_test_keys_loaded
        key_comment_pairs = {bytes(k): bytes(c) for k, c in client.list_keys()}
        public_key_data = ssh_test_key.public_key_data
        if public_key_data not in key_comment_pairs:  # pragma: no cover
            pytest.skip(f"prerequisite {ssh_test_key_type} SSH key not loaded")
        if ssh_test_key.is_suitable():
            assert (
                data.SSHTestKeyDeterministicSignatureClass.SPEC
                in ssh_test_key.expected_signatures
            )
            sig = ssh_test_key.expected_signatures[
                data.SSHTestKeyDeterministicSignatureClass.SPEC
            ]
            expected_signature = sig.signature
            derived_passphrase = sig.derived_passphrase
            signature = bytes(
                client.sign(payload=vault.Vault.UUID, key=public_key_data)
            )
            assert signature == expected_signature, (
                f"SSH signature mismatch ({ssh_test_key_type})"
            )
            signature2 = bytes(
                client.sign(payload=vault.Vault.UUID, key=public_key_data)
            )
            assert signature2 == expected_signature, (
                f"SSH signature mismatch ({ssh_test_key_type})"
            )
            assert (
                vault.Vault.phrase_from_key(public_key_data, conn=client)
                == derived_passphrase
            ), f"SSH signature mismatch ({ssh_test_key_type})"
        else:
            assert (
                data.SSHTestKeyDeterministicSignatureClass.SPEC
                not in ssh_test_key.expected_signatures
            )
            assert not vault.Vault.is_suitable_ssh_key(
                public_key_data, client=None
            ), f"Expected {ssh_test_key_type} key to be unsuitable in general"
            if vault.Vault.is_suitable_ssh_key(
                public_key_data, client=client
            ):  # pragma: no cover [external]
                potential_signatures = {
                    sig_class: sig.signature
                    for sig_class, sig in ssh_test_key.expected_signatures.items()
                    if sig_class
                    != data.SSHTestKeyDeterministicSignatureClass.SPEC
                }
                signature = bytes(
                    client.sign(payload=vault.Vault.UUID, key=public_key_data)
                )
                assert signature in potential_signatures.values()
            else:  # pragma: no cover [external]
                with pytest.raises(ValueError, match="unsuitable SSH key"):
                    vault.Vault.phrase_from_key(public_key_data, conn=client)

class TestSuitableKeys:
    """Test actually talking to the SSH agent: determining suitable keys."""

@Parametrize.SSH_KEY_SELECTION
    def test_ssh_key_selector(
        self,
        monkeypatch: pytest.MonkeyPatch,
        ssh_agent_client_with_test_keys_loaded: ssh_agent.SSHAgentClient,
        key: bytes,
        single: bool,
    ) -> None:
        """The key selector presents exactly the suitable keys.

"Suitable" here means suitability for this SSH agent
        specifically.

"""
        client = ssh_agent_client_with_test_keys_loaded

monkeypatch.setattr(
            ssh_agent.SSHAgentClient,
            "list_keys",
            callables.list_keys_singleton if single else callables.list_keys,
        )
        raw_keys_list = (
            callables.list_keys_singleton()
            if single
            else callables.list_keys()
        )
        keys = [
            pair.key
            for pair in raw_keys_list
            if vault.Vault.is_suitable_ssh_key(pair.key, client=client)
        ]
        n = len(keys)
        if single or n == 1:
            input_text = "yes\n"
            text = "Use this key? yes\n"
        else:
            input_text = f"{1 + keys.index(key)}\n"
            text = (
                f"Your selection? (1-{n}, leave empty to abort): {input_text}"
            )
        b64_key = base64.standard_b64encode(key).decode("ASCII")

@click.command()
        def driver() -> None:
            """Call [`cli_helpers.select_ssh_key`][] directly, as a command."""
            key = cli_helpers.select_ssh_key(client)
            click.echo(base64.standard_b64encode(key).decode("ASCII"))

runner = machinery.CliRunner(mix_stderr=True)
        result = runner.invoke(
            driver, [], input=input_text, catch_exceptions=True
        )
        for snippet in ("Suitable SSH keys:\n", text, f"\n{b64_key}\n"):
            assert result.clean_exit(output=snippet), "expected clean exit"

class TestConstructorFailures:
    """Test actually talking to the SSH agent: constructor failures."""

def test_constructor_bad_running_agent(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
    ) -> None:
        """Fail if the agent address is invalid."""
        with pytest.MonkeyPatch.context() as monkeypatch:
            new_socket_name = (
                running_ssh_agent.socket + "~"
                if isinstance(running_ssh_agent.socket, str)
                else "<invalid//address>"
            )
            monkeypatch.setenv("SSH_AUTH_SOCK", new_socket_name)
            with pytest.raises(OSError):  # noqa: PT011
                ssh_agent.SSHAgentClient()

def test_constructor_no_af_unix_support(self) -> None:
        """Fail without [`socket.AF_UNIX`][] support."""
        assert "posix" in socketprovider.SocketProvider.registry
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setenv("SSH_AUTH_SOCK", "the value doesn't matter")
            monkeypatch.delattr(socket, "AF_UNIX", raising=False)
            with pytest.raises(
                NotImplementedError,
                match="UNIX domain sockets",
            ):
                ssh_agent.SSHAgentClient(socket="posix")

def test_no_ssh_agent_socket_provider_available(
        self,
    ) -> None:
        """Fail if no SSH agent socket provider is available."""
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setitem(
                socketprovider.SocketProvider.registry, "stub_agent", None
            )
            with pytest.raises(ExceptionGroup) as excinfo:
                ssh_agent.SSHAgentClient(
                    socket=["stub_agent", "stub_agent", "stub_agent"]
                )
            assert all([
                isinstance(e, NotImplementedError)
                for e in excinfo.value.exceptions
            ])

class TestOtherConstructorFeatures:
    """Test actually talking to the SSH agent: other constructor features."""

def test_explicit_socket(
        self,
        spawn_ssh_agent: data.SpawnedSSHAgentInfo,
    ) -> None:
        conn = spawn_ssh_agent.client._connection
        ssh_agent.SSHAgentClient(socket=conn)

class TestAgentErrorResponses:
    """Test actually talking to the SSH agent: errors from the SSH agent."""

class Request(NamedTuple):
        """A request for the SSH agent protocol.

Attributes:
            code:
                The expected request code.
            payload:
                The expected payload.  Optional.

"""

code: _types.SSH_AGENTC
        """"""
        payload: bytes | None
        """"""

class Response(NamedTuple):
        """A response for the SSH agent protocol.

Attributes:
            code:
                The desired response code.
            payload:
                The desired response payload.

"""

code: _types.SSH_AGENT
        """"""
        payload: bytes
        """"""

def _make_request_stub(
        self,
        request_response_map: Mapping[Request, Response],
        /,
    ) -> data.RequestFunc:
        """Return a stubbed SSH agent client `request` function.

Args:
            request_response_map:
                A map of request/response pairs.

"""

def request(
            request_code: int | _types.SSH_AGENTC,
            payload: bytes | bytearray,
            /,
            *,
            response_code: Iterable[int | _types.SSH_AGENT]
            | int
            | _types.SSH_AGENT
            | None = None,
        ) -> tuple[int, bytes | bytearray] | bytes | bytearray:
            request_code = _types.SSH_AGENTC(request_code)
            response_code = (
                frozenset({_types.SSH_AGENT.SUCCESS})
                if response_code is None
                else frozenset({_types.SSH_AGENT(response_code)})
                if isinstance(response_code, (int, _types.SSH_AGENT))
                else frozenset(map(_types.SSH_AGENT, response_code))
            )
            response_ = request_response_map.get(
                self.Request(request_code, bytes(payload))
            ) or request_response_map.get(self.Request(request_code, None))
            if response_ is None:  # pragma: no cover [failsafe]
                raise ssh_agent.SSHAgentFailedError(
                    _types.SSH_AGENT.FAILURE.value,
                    "No prepared response for the request "
                    f"({request_code!r}, {payload!r})".encode(),
                )
            code, response = response_
            if code not in response_code:
                raise ssh_agent.SSHAgentFailedError(code.value, response)
            return response

return request

@contextlib.contextmanager
    def _setup_agent_and_request_handler(
        self, request_response_map: Mapping[Request, Response], /
    ) -> Iterator[tuple[pytest.MonkeyPatch, ssh_agent.SSHAgentClient]]:
        # TODO(the-13th-letter): Rewrite using parenthesized
        # with-statements.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        with contextlib.ExitStack() as stack:
            monkeypatch = stack.enter_context(pytest.MonkeyPatch.context())
            client = stack.enter_context(
                ssh_agent.SSHAgentClient.ensure_agent_subcontext()
            )
            monkeypatch.setattr(
                client,
                "request",
                self._make_request_stub(request_response_map),
            )
            yield monkeypatch, client

@Parametrize.TRUNCATED_AGENT_RESPONSES
    def test_truncated_server_response(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
        response: bytes,
    ) -> None:
        """Fail on truncated responses from the SSH agent."""
        del running_ssh_agent
        client = ssh_agent.SSHAgentClient()
        response_stream = io.BytesIO(response)

class PseudoSocket:
            def sendall(self, *args: Any, **kwargs: Any) -> Any:  # noqa: ARG002
                return None

def recv(self, *args: Any, **kwargs: Any) -> Any:
                return response_stream.read(*args, **kwargs)

pseudo_socket = PseudoSocket()
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(client, "_connection", pseudo_socket)
            with pytest.raises(EOFError):
                client.request(255, b"")

@Parametrize.LIST_KEYS_ERROR_RESPONSES
    def test_list_keys_error_responses(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
        response_code: _types.SSH_AGENT,
        response: bytes | bytearray,
        exc_type: type[Exception],
        exc_pattern: str,
    ) -> None:
        """Fail on problems during key listing.

Known problems:

- The agent refuses, or otherwise indicates the operation
            failed.
          - The agent response is truncated.
          - The agent response is overlong.

"""
        del running_ssh_agent
        with self._setup_agent_and_request_handler({
            self.Request(
                _types.SSH_AGENTC.REQUEST_IDENTITIES, None
            ): self.Response(response_code, response),
        }) as contexts:
            _, client = contexts
            with pytest.raises(exc_type, match=exc_pattern):
                client.list_keys()

@Parametrize.SIGN_ERROR_RESPONSES
    def test_sign_error_responses(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
        key: bytes | bytearray,
        check: bool,
        response_code: _types.SSH_AGENT,
        response: bytes | bytearray,
        exc_type: type[Exception],
        exc_pattern: str,
    ) -> None:
        """Fail on problems during signing.

Known problems:

- The key is not loaded into the agent.
          - The agent refuses, or otherwise indicates the operation
            failed.

"""
        del running_ssh_agent
        Pair: TypeAlias = _types.SSHKeyCommentPair
        com = b"no comment"
        loaded_keys = [
            Pair(v.public_key_data, com).toreadonly()
            for v in data.SUPPORTED_KEYS.values()
        ]
        sign_payload = (
            ssh_agent.SSHAgentClient.string(key)
            + ssh_agent.SSHAgentClient.string(b"abc")
            + ssh_agent.SSHAgentClient.uint32(0)
        )
        with self._setup_agent_and_request_handler({
            self.Request(
                _types.SSH_AGENTC.SIGN_REQUEST, sign_payload
            ): self.Response(response_code, response),
        }) as contexts:
            monkeypatch, client = contexts
            monkeypatch.setattr(client, "list_keys", lambda: loaded_keys)
            with pytest.raises(exc_type, match=exc_pattern):
                client.sign(key, b"abc", check_if_key_loaded=check)

@Parametrize.REQUEST_ERROR_RESPONSES
    def test_request_error_responses(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
        request_code: _types.SSH_AGENTC,
        response_code: _types.SSH_AGENT,
        exc_type: type[Exception],
        exc_pattern: str,
    ) -> None:
        """Fail on problems during signing.

Known problems:

- The key is not loaded into the agent.
          - The agent refuses, or otherwise indicates the operation
            failed.

"""
        del running_ssh_agent

# TODO(the-13th-letter): Rewrite using parenthesized
        # with-statements.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        with contextlib.ExitStack() as stack:
            client = stack.enter_context(ssh_agent.SSHAgentClient())
            stack.enter_context(pytest.raises(exc_type, match=exc_pattern))
            client.request(request_code, b"", response_code=response_code)

@Parametrize.QUERY_EXTENSIONS_MALFORMED_RESPONSES
    def test_query_extensions_malformed_responses(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
        response_data: bytes,
    ) -> None:
        """Fail on malformed responses while querying extensions."""
        del running_ssh_agent
        with self._setup_agent_and_request_handler({
            self.Request(
                _types.SSH_AGENTC.EXTENSION,
                ssh_agent.SSHAgentClient.string(b"query"),
            ): self.Response(
                _types.SSH_AGENT.EXTENSION_RESPONSE, response_data
            ),
        }) as contexts:
            _, client = contexts
            with pytest.raises(
                RuntimeError,
                match=r"Malformed response|does not match request",
            ):
                client.query_extensions()

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