[ota] Add allow_plaintext_upload for devices that never migrated to encryption (#19396)

tests/unit_tests/test_espota2_noise.py

@@ -218,6 +218,7 @@ def _upload(
     firmware: bytes,
     noise_psk: str | None,
     plaintext_fallback: bool = False,
+    allow_plaintext_upload: bool = False,
 ) -> None:
     device.start()
     sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
@@ -231,13 +232,18 @@ def _upload(
             Path("firmware.bin"),
             noise_psk=noise_psk,
             plaintext_fallback=plaintext_fallback,
+            allow_plaintext_upload=allow_plaintext_upload,
         )
     finally:
         sock.close()
 
 
 def _run_ota(
-    device: FakeEncryptedDevice, firmware: bytes, tmp_path: Path, noise_psk: str
+    device: FakeEncryptedDevice,
+    firmware: bytes,
+    tmp_path: Path,
+    noise_psk: str,
+    plaintext_fallback: bool = True,
 ) -> int:
     """Drive the retry loop, which is where the plaintext fallback reconnects."""
     path = tmp_path / "firmware.bin"
@@ -249,7 +255,7 @@ def _run_ota(
         None,
         path,
         noise_psk=noise_psk,
-        plaintext_fallback=True,
+        plaintext_fallback=plaintext_fallback,
     )
     return rc
 
@@ -299,11 +305,69 @@ def test_tampered_negotiation_breaks_handshake() -> None:
 def test_client_fails_closed_when_device_lacks_encryption() -> None:
     """With a key configured, a device not offering noise aborts the upload."""
     device = FakeEncryptedDevice(offer_noise=False, require_noise=False)
-    with pytest.raises(espota2.OTAError, match="refusing to send the image"):
+    with pytest.raises(
+        espota2.OTAError, match="refusing to send the image.*allow_plaintext_upload"
+    ):
         _upload(device, b"firmware", PSK)
     device.join_and_check()
 
 
+def test_allow_plaintext_upload_when_device_does_not_offer(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """The explicit opt in sends the image in plaintext to a device that
+    cannot encrypt, naming the option in the warning."""
+    firmware = b"firmware"
+    device = FakeEncryptedDevice(offer_noise=False, require_noise=False)
+    with patch("time.sleep"), caplog.at_level(logging.WARNING):
+        _upload(device, firmware, PSK, allow_plaintext_upload=True)
+    device.join_and_check()
+    assert device.received == firmware
+    assert any("'allow_plaintext_upload' is set" in r.message for r in caplog.records)
+    assert not any("2027.3.0" in r.message for r in caplog.records)
+    assert not any(
+        "Remove it from the configuration" in r.message for r in caplog.records
+    )
+
+
+def test_allow_plaintext_upload_warns_once_device_encrypts(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """The removal warning appears exactly when it is safe to act on: the
+    device offered encryption and accepted the key with the option still set."""
+    pytest.importorskip("aioesphomeapi.noise")
+    firmware = b"firmware"
+    device = FakeEncryptedDevice()
+    with caplog.at_level(logging.WARNING):
+        _upload(device, firmware, PSK, allow_plaintext_upload=True)
+    device.join_and_check()
+    assert device.received == firmware
+    assert any(
+        "Remove it from the configuration now" in r.message for r in caplog.records
+    )
+    with caplog.at_level(logging.WARNING):
+        caplog.clear()
+        _upload(FakeEncryptedDevice(), firmware, PSK)
+    assert not caplog.records
+
+
+def test_allow_plaintext_upload_keeps_wrong_key_failing(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """The opt in only covers a device that does not offer; a rejected key
+    never turns into a plaintext upload."""
+    pytest.importorskip("aioesphomeapi.noise")
+    device = FakeEncryptedDevice(psk=OTHER_PSK, require_noise=False)
+    with (
+        caplog.at_level(logging.WARNING),
+        pytest.raises(espota2.OTAError, match="encryption key correct"),
+    ):
+        _upload(device, b"firmware", PSK, allow_plaintext_upload=True)
+    device.join_and_check()
+    assert device.received != b"firmware"
+    assert not any("plaintext" in r.message for r in caplog.records)
+
+
 # Remove before 2027.3.0
 def test_fallback_when_device_does_not_offer(caplog: pytest.LogCaptureFixture) -> None:
     """The api key is tried opportunistically; an older device that cannot
@@ -519,3 +583,18 @@ def test_recv_serves_buffered_plaintext_without_new_frame() -> None:
     assert wrapper.recv(1) == b"A"  # reads and decrypts one frame
     assert wrapper.recv(1) == b"B"  # served from the buffer, no new frame
     wrapper._decrypt.decrypt.assert_called_once()
+
+
+def test_bare_block_refuses_a_device_that_cannot_encrypt(
+    caplog: pytest.LogCaptureFixture, tmp_path: Path
+) -> None:
+    """What the CLI sends for a bare `encryption:` block: a key with neither
+    fallback. The retry loop never reconnects in plaintext."""
+    device = FakeEncryptedDevice(offer_noise=False, require_noise=False)
+    with patch("time.sleep"), caplog.at_level(logging.WARNING):
+        rc = _run_ota(device, b"firmware", tmp_path, PSK, plaintext_fallback=False)
+    device.join_and_check()
+    assert rc == 1
+    assert device.received != b"firmware"
+    assert any("refusing to send the image" in r.message for r in caplog.records)
+    assert not any("Retrying in plaintext" in r.message for r in caplog.records)

tests/unit_tests/test_main.py

@@ -2115,6 +2115,7 @@ def test_upload_program_ota_success(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -2153,9 +2154,75 @@ def test_upload_program_ota_encryption_key(
         OTA_TYPE_UPDATE_APP,
         key,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
+def test_upload_program_bare_encryption_block_never_falls_back(
+    mock_get_port_type: Mock,
+    tmp_path: Path,
+) -> None:
+    """A bare `ota: encryption:` (the api key inherited by final validate, no
+    option) fails closed against a device that does not offer encryption."""
+    from esphome.components.esphome.ota import ota_esphome_final_validate
+    import esphome.final_validate as fv
+
+    setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path)
+    mock_get_port_type.return_value = "NETWORK"
+    key = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
+    config = {
+        CONF_API: {CONF_ENCRYPTION: {CONF_KEY: key}},
+        CONF_OTA: [{CONF_PLATFORM: CONF_ESPHOME, CONF_PORT: 3232, CONF_ENCRYPTION: {}}],
+    }
+    token = fv.full_config.set(config)
+    try:
+        ota_esphome_final_validate({})
+        config = fv.full_config.get()
+    finally:
+        fv.full_config.reset(token)
+    assert config[CONF_OTA][0][CONF_ENCRYPTION] == {CONF_KEY: key}
+
+    with patch("esphome.espota2.run_ota", return_value=(0, "192.168.1.100")) as run_ota:
+        upload_program(config, MockArgs(), ["192.168.1.100"])
+    assert run_ota.call_args.args[5] == key
+    assert run_ota.call_args.kwargs == {
+        "plaintext_fallback": False,
+        "allow_plaintext_upload": False,
+    }
+
+
+def test_upload_program_ota_allow_plaintext_upload(
+    mock_run_ota: Mock,
+    mock_get_port_type: Mock,
+    tmp_path: Path,
+) -> None:
+    """The uploader side opt in reaches run_ota without the removed fallback."""
+    setup_core(platform=PLATFORM_ESP32, tmp_path=tmp_path)
+    mock_get_port_type.return_value = "NETWORK"
+    mock_run_ota.return_value = (0, "192.168.1.100")
+
+    key = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
+    config = {
+        CONF_OTA: [
+            {
+                CONF_PLATFORM: CONF_ESPHOME,
+                CONF_PORT: 3232,
+                CONF_PASSWORD: "pw",
+                CONF_ENCRYPTION: {CONF_KEY: key, "allow_plaintext_upload": True},
+            }
+        ]
+    }
+    exit_code, _ = upload_program(config, MockArgs(), ["192.168.1.100"])
+
+    assert exit_code == 0
+    assert mock_run_ota.call_args.args[2] == "pw"
+    assert mock_run_ota.call_args.args[5] == key
+    assert mock_run_ota.call_args.kwargs == {
+        "plaintext_fallback": False,
+        "allow_plaintext_upload": True,
+    }
+
+
 def test_upload_program_ota_api_key_opportunistic(
     mock_run_ota: Mock,
     mock_get_port_type: Mock,
@@ -2186,6 +2253,7 @@ def test_upload_program_ota_api_key_opportunistic(
         OTA_TYPE_UPDATE_APP,
         key,
         plaintext_fallback=True,
+        allow_plaintext_upload=False,
     )
 
 
@@ -2214,7 +2282,10 @@ def test_upload_program_ota_no_usable_api_key_stays_plaintext(
 
     assert exit_code == 0
     assert mock_run_ota.call_args.args[5] is None
-    assert mock_run_ota.call_args.kwargs == {"plaintext_fallback": False}
+    assert mock_run_ota.call_args.kwargs == {
+        "plaintext_fallback": False,
+        "allow_plaintext_upload": False,
+    }
 
 
 def test_upload_program_ota_encryption_without_key_fails_closed(
@@ -2274,6 +2345,7 @@ def test_upload_program_ota_with_file_arg(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -2330,6 +2402,7 @@ def test_upload_program_ota_partition_table_with_file_arg(
         OTA_TYPE_UPDATE_PARTITION_TABLE,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -2393,6 +2466,7 @@ def test_upload_program_ota_partition_table_mqttip(
         OTA_TYPE_UPDATE_PARTITION_TABLE,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -2582,6 +2656,7 @@ def test_upload_program_ota_bootloader_with_file_arg(
         OTA_TYPE_UPDATE_BOOTLOADER,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -3077,6 +3152,7 @@ def test_upload_program_ota_with_mqtt_resolution(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -3133,6 +3209,7 @@ def test_upload_program_ota_with_mqtt_empty_broker(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
     # Verify warning was logged
     assert "MQTT IP discovery failed" in caplog.text
@@ -5306,6 +5383,7 @@ def test_upload_program_ota_static_ip_with_mqttip(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -5357,6 +5435,7 @@ def test_upload_program_ota_multiple_mqttip_resolves_once(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )
 
 
@@ -5541,6 +5620,7 @@ def test_upload_program_ota_mqtt_timeout_fallback(
         OTA_TYPE_UPDATE_APP,
         None,
         plaintext_fallback=False,
+        allow_plaintext_upload=False,
     )