From cf3e19019e7f67e44d810e2714acd7866407b6be Mon Sep 17 00:00:00 2001 From: Cai Xin Ying Date: Sat, 6 May 2023 19:45:35 +0800 Subject: [PATCH] Docs/add Chinese translation for api-reference/network/esp_netif.rst --- docs/en/api-reference/network/esp_netif.rst | 221 +++++----- .../zh_CN/api-reference/network/esp_netif.rst | 389 +++++++++++++++++- 2 files changed, 502 insertions(+), 108 deletions(-) diff --git a/docs/en/api-reference/network/esp_netif.rst b/docs/en/api-reference/network/esp_netif.rst index 7a911329e49c..576aa8724ed7 100644 --- a/docs/en/api-reference/network/esp_netif.rst +++ b/docs/en/api-reference/network/esp_netif.rst @@ -1,20 +1,22 @@ ESP-NETIF ========= -The purpose of ESP-NETIF library is twofold: +:link_to_translation:`zh_CN:[中文]` + +The purpose of the ESP-NETIF library is twofold: - It provides an abstraction layer for the application on top of the TCP/IP stack. This will allow applications to choose between IP stacks in the future. -- The APIs it provides are thread safe, even if the underlying TCP/IP stack APIs are not. +- The APIs it provides are thread-safe, even if the underlying TCP/IP stack APIs are not. -ESP-IDF currently implements ESP-NETIF for the lwIP TCP/IP stack only. However, the adapter itself is TCP/IP implementation agnostic and different implementations are possible. +ESP-IDF currently implements ESP-NETIF for the lwIP TCP/IP stack only. However, the adapter itself is TCP/IP implementation-agnostic and allows different implementations. It is also possible to use a custom TCP/IP stack with ESP-IDF, provided it implements BSD API. For more information on building ESP-IDF without lwIP, please refer to :idf_file:`components/esp_netif_stack/README.md`. -Some ESP-NETIF API functions are intended to be called by application code, for example to get/set interface IP addresses, configure DHCP. Other functions are intended for internal ESP-IDF use by the network driver layer. +Some ESP-NETIF API functions are intended to be called by application code, for example, to get or set interface IP addresses, and configure DHCP. Other functions are intended for internal ESP-IDF use by the network driver layer. -In many cases, applications do not need to call ESP-NETIF APIs directly as they are called from the default network event handlers. +In many cases, applications do not need to call ESP-NETIF APIs directly as they are called by the default network event handlers. -ESP-NETIF architecture +ESP-NETIF Architecture ---------------------- .. code-block:: text @@ -45,7 +47,7 @@ ESP-NETIF architecture | | | | | | (D) | (B) | | | | (C) | +-----------------------+ --------+ | | +===========================+ - communication | | NETWORK STACK + COMMUNICATION | | NETWORK STACK DRIVER | | ESP-NETIF | | +------------------+ | | +---------------------------+.........| open/close | @@ -60,96 +62,96 @@ ESP-NETIF architecture ESP-NETIF L2 TAP -Data and event flow in the diagram +Data and Event Flow in the Diagram ---------------------------------- * ``........`` Initialization line from user code to ESP-NETIF and communication driver * ``--<--->--`` Data packets going from communication media to TCP/IP stack and back -* ``********`` Events aggregated in ESP-NETIF propagates to driver, user code and network stack +* ``********`` Events aggregated in ESP-NETIF propagate to the driver, user code, and network stack * ``|`` User settings and runtime configuration -ESP-NETIF interaction +ESP-NETIF Interaction --------------------- -A) User code, boiler plate +A) User code, boilerplate ^^^^^^^^^^^^^^^^^^^^^^^^^^ -Overall application interaction with a specific IO driver for communication media and configured TCP/IP network stack is abstracted using ESP-NETIF APIs and outlined as below: +Overall application interaction with a specific IO driver for communication media and configured TCP/IP network stack is abstracted using ESP-NETIF APIs and is outlined as below: A) Initialization code 1) Initializes IO driver - 2) Creates a new instance of ESP-NETIF and configure with + 2) Creates a new instance of ESP-NETIF and configure it with - * ESP-NETIF specific options (flags, behaviour, name) + * ESP-NETIF specific options (flags, behavior, name) * Network stack options (netif init and input functions, not publicly available) * IO driver specific options (transmit, free rx buffer functions, IO driver handle) 3) Attaches the IO driver handle to the ESP-NETIF instance created in the above steps 4) Configures event handlers - * use default handlers for common interfaces defined in IO drivers; or define a specific handlers for customised behaviour/new interfaces - * register handlers for app related events (such as IP lost/acquired) + * Use default handlers for common interfaces defined in IO drivers; or define a specific handler for customized behavior or new interfaces + * Register handlers for app-related events (such as IP lost or acquired) B) Interaction with network interfaces using ESP-NETIF API - * Getting and setting TCP/IP related parameters (DHCP, IP, etc) - * Receiving IP events (connect/disconnect) - * Controlling application lifecycle (set interface up/down) + 1) Gets and sets TCP/IP-related parameters (DHCP, IP, etc) + 2) Receives IP events (connect or disconnect) + 3) Controls application lifecycle (set interface up or down) -B) Communication driver, IO driver, media driver -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +B) Communication Driver, IO Driver, and Media Driver +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Communication driver plays these two important roles in relation with ESP-NETIF: +Communication driver plays these two important roles in relation to ESP-NETIF: -1) Event handlers: Define behaviour patterns of interaction with ESP-NETIF (for example: ethernet link-up -> turn netif on) +1) Event handlers: Defines behavior patterns of interaction with ESP-NETIF (e.g., ethernet link-up -> turn netif on) -2) Glue IO layer: Adapts the input/output functions to use ESP-NETIF transmit, receive and free receive buffer +2) Glue IO layer: Adapts the input or output functions to use ESP-NETIF transmit, receive, and free receive buffer - * Installs driver_transmit to appropriate ESP-NETIF object, so that outgoing packets from network stack are passed to the IO driver - * Calls :cpp:func:`esp_netif_receive()` to pass incoming data to network stack + * Installs driver_transmit to the appropriate ESP-NETIF object so that outgoing packets from the network stack are passed to the IO driver + * Calls :cpp:func:`esp_netif_receive()` to pass incoming data to the network stack C) ESP-NETIF ^^^^^^^^^^^^ -ESP-NETIF is an intermediary between an IO driver and a network stack, connecting packet data path between these two. As that it provides a set of interfaces for attaching a driver to ESP-NETIF object (runtime) and configuring a network stack (compile time). In addition to that a set of API is provided to control network interface lifecycle and its TCP/IP properties. As an overview, the ESP-NETIF public interface could be divided into these 6 groups: +ESP-NETIF serves as an intermediary between an IO driver and a network stack, connecting the packet data path between the two. It provides a set of interfaces for attaching a driver to an ESP-NETIF object at runtime and configures a network stack during compiling. Additionally, a set of APIs is provided to control the network interface lifecycle and its TCP/IP properties. As an overview, the ESP-NETIF public interface can be divided into six groups: 1) Initialization APIs (to create and configure ESP-NETIF instance) -2) Input/Output API (for passing data between IO driver and network stack) +2) Input or Output API (for passing data between IO driver and network stack) 3) Event or Action API * Used for network interface lifecycle management * ESP-NETIF provides building blocks for designing event handlers -4) Setters and Getters for basic network interface properties -5) Network stack abstraction: enabling user interaction with TCP/IP stack +4) Setters and Getters API for basic network interface properties +5) Network stack abstraction API: enabling user interaction with TCP/IP stack * Set interface up or down * DHCP server and client API * DNS API * `SNTP API`_ -6) Driver conversion utilities +6) Driver conversion utilities API -D) Network stack +D) Network Stack ^^^^^^^^^^^^^^^^ -Network stack has no public interaction with application code with regard to public interfaces and shall be fully abstracted by ESP-NETIF API. +The network stack has no public interaction with application code with regard to public interfaces and shall be fully abstracted by ESP-NETIF API. E) ESP-NETIF L2 TAP Interface ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -The ESP-NETIF L2 TAP interface is ESP-IDF mechanism utilized to access Data Link Layer (L2 per OSI/ISO) for frame reception and transmission from user application. Its typical usage in embedded world might be implementation of non-IP related protocols such as PTP, Wake on LAN and others. Note that only Ethernet (IEEE 802.3) is currently supported. +The ESP-NETIF L2 TAP interface is a mechanism in ESP-IDF used to access Data Link Layer (L2 per OSI/ISO) for frame reception and transmission from the user application. Its typical usage in the embedded world might be the implementation of non-IP-related protocols, e.g., PTP, Wake on LAN. Note that only Ethernet (IEEE 802.3) is currently supported. + +From a user perspective, the ESP-NETIF L2 TAP interface is accessed using file descriptors of VFS, which provides file-like interfacing (using functions like ``open()``, ``read()``, ``write()``, etc). To learn more, refer to :doc:`/api-reference/storage/vfs`. -From user perspective, the ESP-NETIF L2 TAP interface is accessed using file descriptors of VFS which provides a file-like interfacing (using functions like ``open()``, ``read()``, ``write()``, etc). Refer to :doc:`/api-reference/storage/vfs` to learn more. - -There is only one ESP-NETIF L2 TAP interface device (path name) available. However multiple file descriptors with different configuration can be opened at a time since the ESP-NETIF L2 TAP interface can be understood as generic entry point to Layer 2 infrastructure. Important is then specific configuration of particular file descriptor. It can be configured to give an access to specific Network Interface identified by ``if_key`` (e.g. `ETH_DEF`) and to filter only specific frames based on their type (e.g. Ethernet type in case of IEEE 802.3). Filtering only specific frames is crucial since the ESP-NETIF L2 TAP needs to exist along with IP stack and so the IP related traffic (IP, ARP, etc.) should not be passed directly to the user application. Even though such option is still configurable, it is not recommended in standard use cases. Filtering is also advantageous from a perspective the user’s application gets access only to frame types it is interested in and the remaining traffic is either passed to other L2 TAP file descriptors or to IP stack. +There is only one ESP-NETIF L2 TAP interface device (path name) available. However multiple file descriptors with different configurations can be opened at a time since the ESP-NETIF L2 TAP interface can be understood as a generic entry point to the Layer 2 infrastructure. What is important is then the specific configuration of the particular file descriptor. It can be configured to give access to a specific Network Interface identified by ``if_key`` (e.g. `ETH_DEF`) and to filter only specific frames based on their type (e.g. Ethernet type in the case of IEEE 802.3). Filtering only specific frames is crucial since the ESP-NETIF L2 TAP needs to exist along with the IP stack and so the IP-related traffic (IP, ARP, etc.) should not be passed directly to the user application. Even though this option is still configurable, it is not recommended in standard use cases. Filtering is also advantageous from the perspective of the user’s application, as it only gets access to the frame types it is interested in, and the remaining traffic is either passed to other L2 TAP file descriptors or to the IP stack. ESP-NETIF L2 TAP Interface Usage Manual --------------------------------------- @@ -160,87 +162,94 @@ To be able to use the ESP-NETIF L2 TAP interface, it needs to be enabled in Kcon open() ^^^^^^ -Once the ESP-NETIF L2 TAP is registered, it can be opened at path name “/dev/net/tap”. The same path name can be opened multiple times up to :ref:`CONFIG_ESP_NETIF_L2_TAP_MAX_FDS` and multiple file descriptors with with different configuration may access the Data Link Layer frames. +Once the ESP-NETIF L2 TAP is registered, it can be opened at path name “/dev/net/tap”. The same path name can be opened multiple times up to :ref:`CONFIG_ESP_NETIF_L2_TAP_MAX_FDS` and multiple file descriptors with a different configuration may access the Data Link Layer frames. -The ESP-NETIF L2 TAP can be opened with ``O_NONBLOCK`` file status flag to the ``read()`` does not block. Note that the ``write()`` may block in current implementation when accessing a Network interface since it is a shared resource among multiple ESP-NETIF L2 TAP file descriptors and IP stack, and there is currently no queuing mechanism deployed. The file status flag can be retrieved and modified using ``fcntl()``. +The ESP-NETIF L2 TAP can be opened with the ``O_NONBLOCK`` file status flag to make sure the ``read()`` does not block. Note that the ``write()`` may block in the current implementation when accessing a Network interface since it is a shared resource among multiple ESP-NETIF L2 TAP file descriptors and IP stack, and there is currently no queuing mechanism deployed. The file status flag can be retrieved and modified using ``fcntl()``. -On success, ``open()`` returns the new file descriptor (a nonnegative integer). On error, -1 is returned and ``errno`` is set to indicate the error. +On success, ``open()`` returns the new file descriptor (a nonnegative integer). On error, -1 is returned, and ``errno`` is set to indicate the error. ioctl() ^^^^^^^ -The newly opened ESP-NETIF L2 TAP file descriptor needs to be configured prior its usage since it is not bounded to any specific Network Interface and no frame type filter is configured. The following configuration options are available to do so: +The newly opened ESP-NETIF L2 TAP file descriptor needs to be configured prior to its usage since it is not bounded to any specific Network Interface and no frame type filter is configured. The following configuration options are available to do so: - * ``L2TAP_S_INTF_DEVICE`` - bounds the file descriptor to specific Network Interface which is identified by its ``if_key``. ESP-NETIF Network Interface ``if_key`` is passed to ``ioctl()`` as the third parameter. Note that default Network Interfaces ``if_key``'s used in ESP-IDF can be found in :component_file:`esp_netif/include/esp_netif_defaults.h`. - * ``L2TAP_S_DEVICE_DRV_HNDL`` - is other way how to bound the file descriptor to specific Network Interface. In this case the Network interface is identified directly by IO Driver handle (e.g. :cpp:type:`esp_eth_handle_t` in case of Ethernet). The IO Driver handle is passed to ``ioctl()`` as the third parameter. - * ``L2TAP_S_RCV_FILTER`` - sets the filter to frames with this type to be passed to the file descriptor. In case of Ethernet frames, the frames are to be filtered based on Length/Ethernet type field. In case the filter value is set less than or equal to 0x05DC, the Ethernet type field is considered to represent IEEE802.3 Length Field and all frames with values in interval <0, 0x05DC> at that field are to be passed to the file descriptor. The IEEE802.2 logical link control (LLC) resolution is then expected to be performed by user’s application. In case the filter value is set greater than 0x05DC, the Ethernet type field is considered to represent protocol identification and only frames which are equal to the set value are to be passed to the file descriptor. + * ``L2TAP_S_INTF_DEVICE`` - bounds the file descriptor to a specific Network Interface that is identified by its ``if_key``. ESP-NETIF Network Interface ``if_key`` is passed to ``ioctl()`` as the third parameter. Note that default Network Interfaces ``if_key``'s used in ESP-IDF can be found in :component_file:`esp_netif/include/esp_netif_defaults.h`. + * ``L2TAP_S_DEVICE_DRV_HNDL`` - is another way to bound the file descriptor to a specific Network Interface. In this case, the Network interface is identified directly by IO Driver handle (e.g. :cpp:type:`esp_eth_handle_t` in case of Ethernet). The IO Driver handle is passed to ``ioctl()`` as the third parameter. + * ``L2TAP_S_RCV_FILTER`` - sets the filter to frames with the type to be passed to the file descriptor. In the case of Ethernet frames, the frames are to be filtered based on the Length and Ethernet type field. In case the filter value is set less than or equal to 0x05DC, the Ethernet type field is considered to represent IEEE802.3 Length Field, and all frames with values in interval <0, 0x05DC> at that field will be passed to the file descriptor. The IEEE802.2 logical link control (LLC) resolution is then expected to be performed by the user’s application. In case the filter value is set greater than 0x05DC, the Ethernet type field is considered to represent protocol identification and only frames that are equal to the set value are to be passed to the file descriptor. -All above set configuration options have getter counterpart option to read the current settings. +All above-set configuration options have a getter counterpart option to read the current settings. .. warning:: - The file descriptor needs to be firstly bounded to specific Network Interface by ``L2TAP_S_INTF_DEVICE`` or ``L2TAP_S_DEVICE_DRV_HNDL`` to be ``L2TAP_S_RCV_FILTER`` option available. + The file descriptor needs to be firstly bounded to a specific Network Interface by ``L2TAP_S_INTF_DEVICE`` or ``L2TAP_S_DEVICE_DRV_HNDL`` to make ``L2TAP_S_RCV_FILTER`` option available. .. note:: - VLAN tagged frames are currently not recognized. If user needs to process VLAN tagged frames, they need set filter to be equal to VLAN tag (i.e. 0x8100 or 0x88A8) and process the VLAN tagged frames in user application. + VLAN-tagged frames are currently not recognized. If the user needs to process VLAN-tagged frames, they need a set filter to be equal to the VLAN tag (i.e. 0x8100 or 0x88A8) and process the VLAN-tagged frames in the user application. .. note:: - ``L2TAP_S_DEVICE_DRV_HNDL`` is particularly useful when user's application does not require usage of IP stack and so ESP-NETIF is not required to be initialized too. As a result, Network Interface cannot be identified by its ``if_key`` and hence it needs to be identified directly by its IO Driver handle. + ``L2TAP_S_DEVICE_DRV_HNDL`` is particularly useful when the user's application does not require the usage of an IP stack and so ESP-NETIF is not required to be initialized too. As a result, Network Interface cannot be identified by its ``if_key`` and hence it needs to be identified directly by its IO Driver handle. | On success, ``ioctl()`` returns 0. On error, -1 is returned, and ``errno`` is set to indicate the error. -| **EBADF** - not a valid file descriptor. -| **EACCES** - option change is denied in this state (e.g. file descriptor has not be bounded to Network interface yet). -| **EINVAL** - invalid configuration argument. Ethernet type filter is already used by other file descriptor on that same Network interface. -| **ENODEV** - no such Network Interface which is tried to be assigned to the file descriptor exists. -| **ENOSYS** - unsupported operation, passed configuration option does not exists. +| * EBADF - not a valid file descriptor. +| * EACCES - options change is denied in this state (e.g. file descriptor has not been bounded to Network interface yet). +| * EINVAL - invalid configuration argument. Ethernet type filter is already used by other file descriptors on that same Network interface. +| * ENODEV - no such Network Interface which is tried to be assigned to the file descriptor exists. +| * ENOSYS - unsupported operation, passed configuration option does not exist. fcntl() ^^^^^^^ ``fcntl()`` is used to manipulate with properties of opened ESP-NETIF L2 TAP file descriptor. -The following commands manipulate the status flags associated with file descriptor: +The following commands manipulate the status flags associated with the file descriptor: - * ``F_GETFD`` - the function returns the file descriptor flags, the third argument is ignored. + * ``F_GETFD`` - the function returns the file descriptor flags, and the third argument is ignored. * ``F_SETFD`` - sets the file descriptor flags to the value specified by the third argument. Zero is returned. -| On error, -1 is returned, and ``errno`` is set to indicate the error. -| **EBADF** - not a valid file descriptor. -| **ENOSYS** - unsupported command. +| On success, ``ioctl()`` returns 0. On error, -1 is returned, and ``errno`` is set to indicate the error. +| * EBADF - not a valid file descriptor. +| * ENOSYS - unsupported command. read() ^^^^^^ -Opened and configured ESP-NETIF L2 TAP file descriptor can be accessed by ``read()`` to get inbound frames. The read operation can be either blocking or non-blocking based on actual state of ``O_NONBLOCK`` file status flag. When the file status flag is set blocking, the read operation waits until a frame is received and context is switched to other task. When the file status flag is set non-blocking, the read operation returns immediately. In such case, either a frame is returned if it was already queued or the function indicates the queue is empty. The number of queued frames associated with one file descriptor is limited by :ref:`CONFIG_ESP_NETIF_L2_TAP_RX_QUEUE_SIZE` Kconfig option. Once the number of queued frames reach configured threshold, the newly arriving frames are dropped until the queue has enough room to accept incoming traffic (Tail Drop queue management). +Opened and configured ESP-NETIF L2 TAP file descriptor can be accessed by ``read()`` to get inbound frames. The read operation can be either blocking or non-blocking based on the actual state of the ``O_NONBLOCK`` file status flag. When the file status flag is set to blocking, the read operation waits until a frame is received and the context is switched to other tasks. When the file status flag is set to non-blocking, the read operation returns immediately. In such case, either a frame is returned if it was already queued or the function indicates the queue is empty. The number of queued frames associated with one file descriptor is limited by :ref:`CONFIG_ESP_NETIF_L2_TAP_RX_QUEUE_SIZE` Kconfig option. Once the number of queued frames reached a configured threshold, the newly arrived frames are dropped until the queue has enough room to accept incoming traffic (Tail Drop queue management). -| On success, ``read()`` returns the number of bytes read. Zero is returned when size of the destination buffer is 0. On error, -1 is returned, and ``errno`` is set to indicate the error. -| **EBADF** - not a valid file descriptor. -| **EAGAIN** - the file descriptor has been marked non-blocking (``O_NONBLOCK``), and the read would block. +| On success, ``read()`` returns the number of bytes read. Zero is returned when the size of the destination buffer is 0. On error, -1 is returned, and ``errno`` is set to indicate the error. +| * EBADF - not a valid file descriptor. +| * EAGAIN - the file descriptor has been marked non-blocking (``O_NONBLOCK``), and the read would block. write() ^^^^^^^ -A raw Data Link Layer frame can be sent to Network Interface via opened and configured ESP-NETIF L2 TAP file descriptor. User’s application is responsible to construct the whole frame except for fields which are added automatically by the physical interface device. The following fields need to be constructed by the user's application in case of Ethernet link: source/destination MAC addresses, Ethernet type, actual protocol header and user data. See below for more information about Ethernet frame structure. +A raw Data Link Layer frame can be sent to Network Interface via opened and configured ESP-NETIF L2 TAP file descriptor. The user’s application is responsible to construct the whole frame except for fields which are added automatically by the physical interface device. The following fields need to be constructed by the user's application in case of an Ethernet link: source/destination MAC addresses, Ethernet type, actual protocol header, and user data. The length of these fields is as follows: -.. code-block:: text +.. list-table:: + :header-rows: 1 + :widths: 20 20 20 30 + :align: center - +-------------------+-------------------+-------------+------------------------------- --+ - | Destination MAC | Source MAC | Type/Length | Payload (protocol header/data) ... | - +-------------------+-------------------+-------------+------------------------------- --+ - 6B 6B 2B 0-1486B + * - Destination MAC + - Source MAC + - Type/Length + - Payload (protocol header/data) + * - 6 B + - 6 B + - 2 B + - 0-1486 B -In other words, there is no additional frame processing performed by the ESP-NETIF L2 TAP interface. It only checks the Ethernet type of the frame is the same as the filter configured in the file descriptor. If the Ethernet type is different, an error is returned and the frame is not sent. Note that the ``write()`` may block in current implementation when accessing a Network interface since it is a shared resource among multiple ESP-NETIF L2 TAP file descriptors and IP stack, and there is currently no queuing mechanism deployed. +In other words, there is no additional frame processing performed by the ESP-NETIF L2 TAP interface. It only checks the Ethernet type of the frame is the same as the filter configured in the file descriptor. If the Ethernet type is different, an error is returned and the frame is not sent. Note that the ``write()`` may block in the current implementation when accessing a Network interface since it is a shared resource among multiple ESP-NETIF L2 TAP file descriptors and IP stack, and there is currently no queuing mechanism deployed. -| On success, ``write()`` returns the number of bytes written. Zero is returned when size of the input buffer is 0. On error, -1 is returned, and ``errno`` is set to indicate the error. -| **EBADF** - not a valid file descriptor. -| **EBADMSG** - Ethernet type of the frame is different then file descriptor configured filter. -| **EIO** - Network interface not available or busy. +| On success, ``write()`` returns the number of bytes written. Zero is returned when the size of the input buffer is 0. On error, -1 is returned, and ``errno`` is set to indicate the error. +| * EBADF - not a valid file descriptor. +| * EBADMSG - The Ethernet type of the frame is different from the file descriptor configured filter. +| * EIO - Network interface not available or busy. close() ^^^^^^^ -Opened ESP-NETIF L2 TAP file descriptor can be closed by the ``close()`` to free its allocated resources. The ESP-NETIF L2 TAP implementation of ``close()`` may block. On the other hand, it is thread safe and can be called from different task than the file descriptor is actually used. If such situation occurs and one task is blocked in I/O operation and another task tries to close the file descriptor, the first task is unblocked. The first's task read operation then ends with error. +Opened ESP-NETIF L2 TAP file descriptor can be closed by the ``close()`` to free its allocated resources. The ESP-NETIF L2 TAP implementation of ``close()`` may block. On the other hand, it is thread-safe and can be called from a different task than the file descriptor is actually used. If such a situation occurs and one task is blocked in the I/O operation and another task tries to close the file descriptor, the first task is unblocked. The first's task read operation then ends with an error. | On success, ``close()`` returns zero. On error, -1 is returned, and ``errno`` is set to indicate the error. -| **EBADF** - not a valid file descriptor. +| * EBADF - not a valid file descriptor. select() ^^^^^^^^ -Select is used in a standard way, just :ref:`CONFIG_VFS_SUPPORT_SELECT` needs to be enabled to be the ``select()`` function available. +Select is used in a standard way, just :ref:`CONFIG_VFS_SUPPORT_SELECT` needs to be enabled to make the ``select()`` function available. .. _esp_netif-sntp-api: @@ -248,21 +257,20 @@ Select is used in a standard way, just :ref:`CONFIG_VFS_SUPPORT_SELECT` needs to SNTP API -------- -You can find a brief introduction to SNTP in general, its initialization code and basic modes in :ref:`system-time-sntp-sync` section in the :doc:`System Time Document`. +You can find a brief introduction to SNTP in general, its initialization code, and basic modes in Section :ref:`system-time-sntp-sync` in :doc:`System Time `. -This section provides more details about specific use cases of SNTP service, with statically configured servers, or using DHCP provided servers, or both. -The workflow is usually very simple: +This section provides more details about specific use cases of the SNTP service, with statically configured servers, or use the DHCP-provided servers, or both. The workflow is usually very simple: 1) Initialize and configure the service using :cpp:func:`esp_netif_sntp_init()`. -2) Start the service via :cpp:func:`esp_netif_sntp_start()`. This step is not needed if we auto-started the service in the previous step (default). It's useful to start the service explicitly after connecting, if we want to use DHCP obtained NTP servers. (This option needs to be enabled before connecting, but SNTP service should be started after) +2) Start the service via :cpp:func:`esp_netif_sntp_start()`. This step is not needed if we auto-started the service in the previous step (default). It's useful to start the service explicitly after connecting if we want to use the DHCP-obtained NTP servers. Please note, this option needs to be enabled before connecting, but the SNTP service should be started after. 3) Wait for the system time to synchronize using :cpp:func:`esp_netif_sntp_sync_wait()` (only if needed). 4) Stop and destroy the service using :cpp:func:`esp_netif_sntp_deinit()`. -Basic mode with statically defined server(s) +Basic Mode with Statically Defined Server(s) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Initialize the module with the default configuration after connecting to network. Note that it's possible to provide multiple NTP servers in the configuration struct: +Initialize the module with the default configuration after connecting to the network. Note that it's possible to provide multiple NTP servers in the configuration struct: .. code-block:: c @@ -272,20 +280,19 @@ Initialize the module with the default configuration after connecting to network .. note:: - If we want to configure multiple SNTP servers, we have to update lwIP configuration :ref:`CONFIG_LWIP_SNTP_MAX_SERVERS`. + If we want to configure multiple SNTP servers, we have to update the lwIP configuration :ref:`CONFIG_LWIP_SNTP_MAX_SERVERS`. -Use DHCP obtained SNTP server(s) +Use DHCP-Obtained SNTP Server(s) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -First of all, we have to enable lwIP configuration option :ref:`CONFIG_LWIP_DHCP_GET_NTP_SRV`. -Then we have to initialize the SNTP module with the DHCP option and no NTP server: +First of all, we have to enable the lwIP configuration option :ref:`CONFIG_LWIP_DHCP_GET_NTP_SRV`. Then we have to initialize the SNTP module with the DHCP option and without the NTP server: .. code-block:: c esp_sntp_config_t config = ESP_NETIF_SNTP_DEFAULT_CONFIG_MULTIPLE(0, {} ); - config.start = false; // start SNTP service explicitly - config.server_from_dhcp = true; // accept NTP offer from DHCP server + config.start = false; // start the SNTP service explicitly + config.server_from_dhcp = true; // accept the NTP offer from the DHCP server esp_netif_sntp_init(&config); Then, once we're connected, we could start the service using: @@ -296,37 +303,37 @@ Then, once we're connected, we could start the service using: .. note:: - It's also possible to start the service during initialization (default ``config.start=true``). This would likely cause the initial SNTP request to fail (since we are not connected yet) and thus some backoff time for subsequent requests. + It's also possible to start the service during initialization (default ``config.start=true``). This would likely to cause the initial SNTP request to fail (since we are not connected yet) and lead to some back-off time for subsequent requests. -Use both static and dynamic servers +Use Both Static and Dynamic Servers ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Very similar to the scenario above (DHCP provided SNTP server), but in this configuration we need to make sure that the static server configuration is refreshed when obtaining NTP servers by DHCP. The underlying lwIP code cleans up the rest of the list of NTP servers when DHCP provided information gets accepted. Thus the ESP-NETIF SNTP module saves the statically configured server(s) and reconfigures them after obtaining DHCP lease. +Very similar to the scenario above (DHCP provided SNTP server), but in this configuration, we need to make sure that the static server configuration is refreshed when obtaining NTP servers by DHCP. The underlying lwIP code cleans up the rest of the list of NTP servers when the DHCP-provided information gets accepted. Thus the ESP-NETIF SNTP module saves the statically configured server(s) and reconfigures them after obtaining a DHCP lease. -The typical configuration now looks as per below, providing the specific ``IP_EVENT`` to update the config and index of the first server to reconfigure (for example setting ``config.index_of_first_server=1`` would keep DHCP provided server at index 0, and the statically configured server at index 1). +The typical configuration now looks as per below, providing the specific ``IP_EVENT`` to update the config and index of the first server to reconfigure (for example setting ``config.index_of_first_server=1`` would keep the DHCP provided server at index 0, and the statically configured server at index 1). .. code-block:: c esp_sntp_config_t config = ESP_NETIF_SNTP_DEFAULT_CONFIG("pool.ntp.org"); - config.start = false; // start SNTP service explicitly (after connecting) - config.server_from_dhcp = true; // accept NTP offers from DHCP server - config.renew_servers_after_new_IP = true; // let esp-netif update configured SNTP server(s) after receiving DHCP lease + config.start = false; // start the SNTP service explicitly (after connecting) + config.server_from_dhcp = true; // accept the NTP offers from DHCP server + config.renew_servers_after_new_IP = true; // let esp-netif update the configured SNTP server(s) after receiving the DHCP lease config.index_of_first_server = 1; // updates from server num 1, leaving server 0 (from DHCP) intact config.ip_event_to_renew = IP_EVENT_STA_GOT_IP; // IP event on which we refresh the configuration Then we start the service normally with :cpp:func:`esp_netif_sntp_start()`. -ESP-NETIF programmer's manual +ESP-NETIF Programmer's Manual ----------------------------- -Please refer to the example section for basic initialization of default interfaces: +Please refer to the following example to understand the initialization process of the default interface: .. only:: SOC_WIFI_SUPPORTED - - WiFi Station: :example_file:`wifi/getting_started/station/main/station_example_main.c` + - Wi-Fi Station: :example_file:`wifi/getting_started/station/main/station_example_main.c` - Ethernet: :example_file:`ethernet/basic/main/ethernet_example_main.c` @@ -334,15 +341,15 @@ Please refer to the example section for basic initialization of default interfac .. only:: CONFIG_ESP_WIFI_SOFTAP_SUPPORT - - WiFi Access Point: :example_file:`wifi/getting_started/softAP/main/softap_example_main.c` + - Wi-Fi Access Point: :example_file:`wifi/getting_started/softAP/main/softap_example_main.c` -For more specific cases please consult this guide: :doc:`/api-reference/network/esp_netif_driver`. +For more specific cases, please consult this guide: :doc:`/api-reference/network/esp_netif_driver`. .. only:: SOC_WIFI_SUPPORTED - WiFi default initialization - ^^^^^^^^^^^^^^^^^^^^^^^^^^^ + Wi-Fi Default Initialization + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The initialization code as well as registering event handlers for default interfaces, such as softAP and station, are provided in separate APIs to facilitate simple startup code for most applications: @@ -352,15 +359,15 @@ For more specific cases please consult this guide: :doc:`/api-reference/network/ * :cpp:func:`esp_netif_create_default_wifi_ap()` - Please note that these functions return the ``esp_netif`` handle, i.e. a pointer to a network interface object allocated and configured with default settings, which as a consequence, means that: + Please note that these functions return the ``esp_netif`` handle, i.e. a pointer to a network interface object allocated and configured with default settings, as a consequence, which means that: * The created object has to be destroyed if a network de-initialization is provided by an application using :cpp:func:`esp_netif_destroy_default_wifi()`. - * These *default* interfaces must not be created multiple times, unless the created handle is deleted using :cpp:func:`esp_netif_destroy()`. + * These *default* interfaces must not be created multiple times unless the created handle is deleted using :cpp:func:`esp_netif_destroy()`. .. only:: CONFIG_ESP_WIFI_SOFTAP_SUPPORT - * When using Wifi in ``AP+STA`` mode, both these interfaces has to be created. + * When using Wi-Fi in ``AP+STA`` mode, both these interfaces have to be created. API Reference @@ -375,7 +382,7 @@ API Reference .. only:: SOC_WIFI_SUPPORTED - WiFi default API reference - ^^^^^^^^^^^^^^^^^^^^^^^^^^ + Wi-Fi Default API Reference + ^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. include-build-file:: inc/esp_wifi_default.inc diff --git a/docs/zh_CN/api-reference/network/esp_netif.rst b/docs/zh_CN/api-reference/network/esp_netif.rst index bc4a08a11c1b..b3e9f5545fba 100644 --- a/docs/zh_CN/api-reference/network/esp_netif.rst +++ b/docs/zh_CN/api-reference/network/esp_netif.rst @@ -1 +1,388 @@ -.. include:: ../../../en/api-reference/network/esp_netif.rst \ No newline at end of file +ESP-NETIF +========= + +:link_to_translation:`en:[English]` + +ESP-NETIF 库的作用主要体现在以下两方面： + +- 在 TCP/IP 协议栈之上为应用程序提供抽象层，允许应用程序在 IP 栈间选择。 +- 在底层 TCP/IP 协议栈 API 非线程安全的情况下，也能提供线程安全的 API。 + +ESP-IDF 目前只为 lwIP TCP/IP 协议栈实现了 ESP-NETIF。然而，该适配器本身不依赖特定 TCP/IP 实现，因而支持不同实现方式。 + +ESP-IDF 支持实现了 BSD API 的自定义 TCP/IP 协议栈。有关不使用 lwIP 时构建 ESP-IDF 的详细信息，请参阅 :idf_file:`components/esp_netif_stack/README.md`。 + +部分 ESP-NETIF 的 API 函数可以被应用程序直接调用，如：获取或设置接口 IP 地址、配置 DHCP 等。其他 ESP-NETIF 的 API 函数则供网络驱动层在 ESP-IDF 内部调用。 + +应用程序通常无需直接调用 ESP-NETIF 的 API，它们会由默认网络事件句柄调用。 + +ESP-NETIF 架构 +---------------------- + +.. code-block:: text + + + | (A) 用户代码 | + | Apps | + .................| 初始化 设置 事件 | + . +----------------------------------------+ + . . | * + . . | * + --------+ +===========================+ * +-----------------------+ + | | new/config get/set/apps | * | init | + | | |...*.....| Apps (DHCP, SNTP) | + | |---------------------------| * | | + 初始化 | | |**** | | + 启动 |************| 事件句柄 |*********| DHCP | + 停止 | | | | | + | |---------------------------| | | + | | | | NETIF | + +-----| | | +-----------------+ | + | glue|---<----|---| esp_netif_transmit |--<------| netif_output | | + | | | | | | | | + | |--->----|---| esp_netif_receive |-->------| netif_input | | + | | | | | + ----------------+ | + | |...<....|...| esp_netif_free_rx_buffer |...<.....| packet buffer | + +-----| | | | | | | + | | | | | | (D) | + (B) | | | | (C) | +-----------------------+ + --------+ | | +===========================+ + 通信 | | 网络堆栈 + 驱动 | | ESP-NETIF + | | +------------------+ + | | +---------------------------+.........| 开启/关闭 | + | | | | | | + | -<--| l2tap_write |-----<---| 写入 | + | | | | | + ---->--| esp_vfs_l2tap_eth_filter |----->---| 读取 | + | | | | + | (E) | +------------------+ + +---------------------------+ + 用户代码 + ESP-NETIF L2 TAP + + +图中不同线段对应的数据流和事件流 +----------------------------------------------- + +* ``........`` 从用户代码到 ESP-NETIF 和通信驱动的初始化线。 + +* ``--<--->--`` 数据包在通信媒介与 TCP/IP 协议栈之间往返。 + +* ``********`` 聚集在 ESP-NETIF 中的事件传递到驱动程序、用户代码和网络堆栈中。 + +* ``|`` 用户设置及运行时间配置。 + +ESP-NETIF 交互 +--------------------- + +A) 用户代码样板 +^^^^^^^^^^^^^^^^^^^^^^^^^^ + +通过使用 ESP-NETIF API 抽象，应用程序与用于通信介质的特定 IO 驱动程序以及配置的 TCP/IP 网络栈之间的交互可以概括如下： + +A) 初始化代码 + + 1) 初始化 IO 驱动 + 2) 创建新的 ESP-NETIF 实例，并完成以下配置： + + * ESP-NETIF 的特定选项（flags、行为、名称） + * 网络栈堆选项（netif init 和 input 函数，非公开信息） + * IO 驱动的特定选项（发送、释放 rx 缓冲区功能、IO 驱动句柄） + + 3) 将 IO 驱动句柄附加到上述步骤所创建的 ESP-NETIF 实例 + 4) 配置事件句柄 + + * 对 IO 驱动定义的公共接口使用默认句柄；或为定制的行为或新接口定义特定的句柄 + * 为应用程序相关事件（如 IP 丢失或获取）注册句柄 + +B) 通过 ESP-NETIF API 与网络接口交互 + + 1) 获取、设置 TCP/IP 相关参数（如 DHCP，IP 等） + 2) 接收 IP 事件（连接或断连） + 3) 控制应用程序生命周期（启用或禁用接口） + + +B) 通信驱动、IO 驱动和媒介驱动 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +对于 ESP-NETIF，通信驱动具有以下两个重要作用： + +1) 事件句柄：定义与 ESP-NETIF 交互的行为模式（如：连接以太网 -> 开启 netif） + +2) 胶合 IO 层：调整输入或输出函数以使用 ESP-NETIF 的传输、接收，并清空接收缓冲区 + + * 给适当的 ESP-NETIF 对象安装 driver_transmit，以便将网络堆栈中传出的数据包传输给 IO 驱动 + * 调用函数 :cpp:func:`esp_netif_receive()` 以便将传入的数据传输给网络堆栈 + + +C) ESP-NETIF +^^^^^^^^^^^^ + +ESP-NETIF 是 IO 驱动和网络堆栈间的媒介，用于连通两者之间的数据包传输路径。它提供了一组接口，用于在运行时将驱动程序附加到 ESP-NETIF 对象并在编译期间配置网络堆栈。此外，ESP-NETIF 还提供了一组 API，用于控制网络接口的生命周期及其 TCP/IP 属性。ESP-NETIF 的公共接口大体上可以分为以下六组： + +1) 初始化 API（用于创建并配置 ESP-NETIF 实例） +2) 输入或输出 API（用于在 IO 驱动和网络堆栈间传输数据） +3) 事件或行为 API + + * 管理网络接口生命周期 + * ESP-NETIF 为设计事件句柄提供了构建模块 + +4) 基本网络接口属性设置器和获取器 API +5) 网络堆栈抽象 API：实现用户与 TCP/IP 堆栈交互 + + * 启用或禁用接口 + * DHCP 服务器和客户端 API + * DNS API + * `SNTP API`_ + +6) 驱动转换工具 API + + +D) 网络堆栈 +^^^^^^^^^^^^^^^^ + +网络堆栈与应用程序代码在公共接口方面无公开交互，需通过 ESP-NETIF API 实现完全抽象。 + + +E) ESP-NETIF L2 TAP 接口 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +ESP-NETIF L2 TAP 接口是 ESP-IDF 访问用户应用程序中的数据链路层（OSI/ISO 中的 L2）以进行帧接收和传输的机制。在嵌入式开发中，它通常用于实现非 IP 相关协议，如 PTP 和 Wake on LAN 等。请注意，目前 ESP-NETIF L2 TAP 接口仅支持以太网 (IEEE 802.3)。 + +使用 VFS 的文件描述符访问 ESP-NETIF L2 TAP 接口，VFS 文件描述符会提供类似文件的接口（调用 ``open()``、 ``read()``、 ``write()`` 等函数访问），详情请参阅 :doc:`/api-reference/storage/vfs`。 + +ESP-NETIF 只提供一个 L2 TAP 接口设备（路径名），但由于 ESP-NETIF L2 TAP 接口也可作为第二层基础设施的通用入口点，因此可以同时打开多个不同配置的文件描述符。特定文件描述符的具体配置很关键，它可以配置为仅允许访问由 ``if_key`` （如 `ETH_DEF`）标识的特定网络接口，并根据帧类型（如 IEEE 802.3 中的以太网类型）过滤特定帧。由于 ESP-NETIF L2 TAP 需要与 IP 堆栈同时存在，因此不应将 IP 相关流量（IP、ARP 等）直接传递给用户应用程序，此时则需要通过配置过滤特定帧实现这一点。在未过滤的情况下，即使该选项仍可配置，也不建议在标准用例中使用。过滤的另一优势在于，过滤后，用户应用程序只能访问它感兴趣的帧类型，其余的流量会传递到其他 L2 TAP 文件描述符或 IP 堆栈。 + +ESP-NETIF L2 TAP 接口使用手册 +--------------------------------------- + +初始化 +^^^^^^^^^^^^^^ +要使用 ESP-NETIF L2 TAP 接口，需要首先通过 Kconfig 配置 :ref:`CONFIG_ESP_NETIF_L2_TAP` 启用接口，随后通过 :cpp:func:`esp_vfs_l2tap_intf_register()` 注册。请在完成上述步骤后再使用 VFS 函数。 + +open() +^^^^^^ +ESP-NETIF L2 TAP 注册完成后，可使用路径名 "/dev/net/tap" 访问。同一路径名最多可以被打开 :ref:`CONFIG_ESP_NETIF_L2_TAP_MAX_FDS` 次，多个具有不同配置的文件描述符可以访问数据链路层的各个帧。 + +ESP-NETIF L2 TAP 可以使用 ``O_NONBLOCK`` 文件状态标志打开，确保 ``read()`` 不会阻塞。请注意，在当前实现中，当访问网络接口时，由于网络接口被多个 ESP-NETIF L2 TAP 文件描述符和 IP 栈共享，且缺乏列队机制，因此 ``write()`` 可能会受阻塞。使用 ``fcntl()`` 检索和修改文件状态标志。 + +成功时，``open()`` 返回新的文件描述符（非负整数）。出错时，返回 -1，并设置 ``errno`` 以标识错误。 + +ioctl() +^^^^^^^ +由于新打开的 ESP-NETIF L2 TAP 文件描述符尚未绑定任意网络接口或配置任意帧类型过滤器，使用前，用户需通过以下选项完成配置： + + * ``L2TAP_S_INTF_DEVICE`` - 将文件描述符绑定到特定网络接口的选项，该网络接口由其 ``if_key`` 标识。 ESP-NETIF 网络接口的 ``if_key`` 作为第三个参数传输给 ``ioctl()``。 ESP-IDF 中，默认网络接口 ``if_key`` 的使用存放在 :component_file:`esp_netif/include/esp_netif_defaults.h` 头文件中。 + * ``L2TAP_S_DEVICE_DRV_HNDL`` - 将文件描述符绑定到特定网络接口的另一选项。此时，网络接口直接由其 IO 驱动句柄（例如以太网中的 :cpp:type:`esp_eth_handle_t`）标识。IO 驱动句柄将作为第三个参数传输给 ``ioctl()``。 + * ``L2TAP_S_RCV_FILTER`` - 设置过滤器，将特定类型的帧传递到文件描述符。在以太网中，帧是基于长度和以太网类型字段过滤的。如果过滤器值设置为小于或等于 0x05DC，则将以太网类型字段视作 IEEE802.3 长度字段，并将该字段中所有值在 <0, 0x05DC> 区间内的帧传递到文件描述符中。随后，由用户应用程序执行 IEEE802.2 逻辑链路控制 (LLC) 的解析。如果过滤器值设置为大于 0x05DC，则将以太网类型字段视为代表协议标识，仅将与设置值相等的帧传递到文件描述符中。 + +上述配置选项都支持通过对应获取器选项读取当前配置。 + +.. warning:: + 首先调用 ``L2TAP_S_INTF_DEVICE`` 或 ``L2TAP_S_DEVICE_DRV_HNDL`` 将文件描述符绑定到特定网络接口，随后方可调用 ``L2TAP_S_RCV_FILTER`` 选项。 + +.. note:: + 当前不支持识别 VLAN 标记帧。如果用户需要处理 VLAN 标记帧，应将过滤器设置为等于 VLAN 标记（即 0x8100 或 0x88A8），并在用户应用程序中处理 VLAN 标记帧。 + +.. note:: + 当用户应用程序不需要使用 IP 栈时， ``L2TAP_S_DEVICE_DRV_HNDL`` 将非常适用，也无需初始化 ESP-NETIF。但在此情况下，网络接口无法通过 ``if_key`` 来识别，需要通过 IO 驱动程序句柄直接标识网络接口。 + +| 成功时，``ioctl()`` 返回 0。出错时，返回 -1，并设置 ``errno`` 以指示错误类型: +| * EBADF - 文件描述符无效。 +| * EACCES - 此状态下无法改变选项（例如文件描述符尚未绑定到网络接口）。 +| * EINVAL - 配置参数无效。同一网络接口上的其他文件描述符已经使用了以太网类型过滤器。 +| * ENODEV - 此文件描述符尝试分配给的网络接口不存在。 +| * ENOSYS - 不支持该操作，传递的配置选项不存在。 + +fcntl() +^^^^^^^ +``fcntl()`` 配置已开启的 ESP-NETIF L2 TAP 文件描述符属性。 + +以下命令调控与文件描述符相关的状态标志： + + * ``F_GETFD`` - 函数返回文件描述符标志，忽略第三个参数。 + * ``F_SETFD`` - 将文件描述符标志设置为第三个参数的指定值。返回零。 + +| 成功时，``ioctl()`` 返回 0。出错时，返回 -1，并设置 ``errno`` 以指示错误类型。 +| * EBADF - 文件描述符无效。 +| * ENOSYS - 不支持该命令。 + +read() +^^^^^^ +已开启并完成配置的 ESP-NETIF L2 TAP 文件描述符可通过 ``read()`` 获取入站帧。读取可以是阻塞或非阻塞的，具体取决于 ``O_NONBLOCK`` 文件状态标志的实际状态。当文件状态标志设置为阻塞时，读取程序将等待，直到接收到帧，并将上下文切换到其他任务。当文件状态标志设置为非阻塞时，立即返回读取程序。在此情况下，如果已经帧已经入队，则返回一帧，否则函数指示队列为空。与文件描述符关联的队列帧数量受 :ref:`CONFIG_ESP_NETIF_L2_TAP_RX_QUEUE_SIZE` Kconfig 选项限制。一旦队列里帧的数量达到配置的阈值，新到达的帧将被丢弃，直到队列有足够的空间接受传入的流量（队尾丢弃队列管理）。 + +| 成功时，read() 函数返回读取的字节数。当目标缓冲区的大小为 0 时，函数返回 0。出错时，函数返回 -1，并设置 ``errno`` 以指示错误类型。 +| * EBADF - 文件描述符无效。 +| * EAGAIN - 文件描述符标记为非阻塞 (``O_NONBLOCK``)，但读取受阻塞。 + +write() +^^^^^^^ +通过已开启并完成配置的 ESP-NETIF L2 TAP 文件描述符可以将原始数据链路层帧发送到网络接口，用户应用程序负责构建除物理接口设备自动添加的字段外的整个帧。在以太网链路中，用户应用程序需要构建以下字段：源或目的 MAC 地址、以太网类型、实际协议头和用户数据，字段长度如下表： + +.. list-table:: + :header-rows: 1 + :widths: 20 20 20 30 + :align: center + + * - 目的 MAC + - 源 MAC + - 类型/长度 + - 负载（协议头/数据） + * - 6 B + - 6 B + - 2 B + - 0-1486 B + +换句话说，ESP-NETIF L2 TAP 接口不会对数据帧进行额外处理，只会检查数据帧的以太网类型是否与文件描述符配置的过滤器相同。如果以太网类型不同，则会返回错误，并且不发送数据帧。需要注意的是，由于网络接口是由多个 ESP-NETIF L2 TAP 文件描述符和 IP 栈共享的资源，且当前缺乏列队机制，当前实现中的 ``write()`` 在进入网络接口时可能会受阻塞，。 + +| 成功时，``write()`` 返回已写入的字节数。如果输入缓冲区的大小为 0，则返回 0。出错时，则返回 -1，并设置 ``errno`` 以指示错误类型。 +| * EBADF - 文件描述符无效。 +| * EBADMSG - 帧的以太网类型与文件描述符配置的过滤器不同。 +| * EIO - 网络接口不可用或正忙。 + +close() +^^^^^^^ +已开启的 ESP-NETIF L2 TAP 文件描述符可以通过 ``close()`` 函数关闭，释放其分配到的资源。ESP-NETIF L2 TAP 实现的 ``close()`` 函数可能会受阻塞，但它是线程安全的，可以从与实际使用文件描述符的任务不同的任务中调用。如果出现一个任务在 I/O 操作中被阻塞、另一个任务试图关闭文件描述符的情况，则第一个任务会解除阻塞，其读取程序以错误结束。 + +| 成功时，``close()`` 返回 0。出错时，则返回 -1， 并设置 ``errno`` 以指示错误类型。 +| * EBADF - 文件描述符无效。 + +select() +^^^^^^^^ +``select()`` 函数按标准方法使用，启用 :ref:`CONFIG_VFS_SUPPORT_SELECT` 即可使用该函数。 + + +.. _esp_netif-sntp-api: + +SNTP API +-------- + +SNTP 的简要介绍、初始化代码和基本模式请参阅 :doc:`系统时间 ` 的 :ref:`system-time-sntp-sync` 小节。 + +本节介绍了使用 SNTP 服务特定用例的详细信息，包括静态配置的服务器、使用 DHCP 提供的服务器或两者兼备的情况，操作流程如下： + +1) 调用 :cpp:func:`esp_netif_sntp_init()` 初始化服务并完成配置。 +2) 调用 :cpp:func:`esp_netif_sntp_start()` 启动服务。如果在前一步中已经默认启动了服务，则不需要此步骤。如果需使用通过 DHCP 获取的 NTP 服务器，推荐在完成连接后显式启动该服务。注意，应在连接前启用通过 DHCP 获取的 NTP 服务器选项，并在连接后再启用 SNTP 服务。 +3) 需要时，可调用 :cpp:func:`esp_netif_sntp_sync_wait()` 等待系统时间同步。 +4) 调用 :cpp:func:`esp_netif_sntp_deinit()` 停止并销毁服务。 + + +使用静态定义服务器的基本模式 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +连接到网络后，使用默认配置初始化该模块。注意，在配置结构体中可提供多个 NTP 服务器： + +.. code-block:: c + + esp_sntp_config_t config = ESP_NETIF_SNTP_DEFAULT_CONFIG_MULTIPLE(2, + ESP_SNTP_SERVER_LIST("time.windows.com", "pool.ntp.org" ) ); + esp_netif_sntp_init(&config); + +.. note:: + + 要配置多个 SNTP 服务器，需要更新 lwIP 配置，请参阅 :ref:`CONFIG_LWIP_SNTP_MAX_SERVERS`。 + + +使用 DHCP 获取的 SNTP 服务器 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +首先，激活 lwIP 配置选项，相关配置请参阅 :ref:`CONFIG_LWIP_DHCP_GET_NTP_SRV`。其次，在使用 DHCP 选项、且不使用 NTP 服务器的情况下初始化 SNTP 模块，代码如下： + +.. code-block:: c + + esp_sntp_config_t config = ESP_NETIF_SNTP_DEFAULT_CONFIG_MULTIPLE(0, {} ); + config.start = false; // 启动 SNTP 服务 + config.server_from_dhcp = true; // 接收来自 DHCP 服务器的 NTP 服务提供方案 + esp_netif_sntp_init(&config); + +连接成功后，可通过以下代码启动服务器： + +.. code-block:: c + + esp_netif_sntp_start(); + +.. note:: + + 也可选择在初始化期间启动服务（即默认 ``config.start=true``）。注意，此时连接尚未完成，可能导致初始 SNTP 请求失败，并增加后续各次请求之间的延迟时间。 + + +同时使用静态和动态服务器 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +同时使用静态和动态服务器的流程与使用 DHCP 获取的 SNTP 服务器基本相同。配置时，用户应确保在通过 DHCP 获取 NTP 服务器时刷新静态服务器配置。底层 lwIP 代码会在接受 DHCP 提供的信息时清理其余的 NTP 服务器列表。因此，ESP-NETIF SNTP 模块会保存静态配置的服务器，并在获取 DHCP 租约后对其重新配置。 + +典型配置依次如下，提供特定 ``IP_EVENT`` 更新配置，并提供第一个服务器的索引完成重新配置（例如，设置 ``config.index_of_first_server=1`` 会将 DHCP 提供的服务器保留在索引 0，而将静态配置的服务器保留在索引 1）。 + +.. code-block:: c + + esp_sntp_config_t config = ESP_NETIF_SNTP_DEFAULT_CONFIG("pool.ntp.org"); + config.start = false; // 启动 SNTP 服务（连接成功后） + config.server_from_dhcp = true; // 接收来自 DHCP 服务器的 NTP 服务提供方案 + config.renew_servers_after_new_IP = true; // 让 esp-netif 在接收到 DHCP 租约后更新配置的 SNTP 服务器 + config.index_of_first_server = 1; // 服务器 1 开始更新，保留从 DHCP 获取的服务器 0 的设置 + config.ip_event_to_renew = IP_EVENT_STA_GOT_IP; // 基于 IP 事件刷新配置 + +随后，调用 :cpp:func:`esp_netif_sntp_start()` 启用服务。 + + +ESP-NETIF 编程手册 +----------------------------- + +请参阅示例部分，了解默认接口的基本初始化： + + +.. only:: SOC_WIFI_SUPPORTED + + - Wi-Fi 基站 :example_file:`wifi/getting_started/station/main/station_example_main.c` + +- 以太网 :example_file:`ethernet/basic/main/ethernet_example_main.c` + +- L2 TAP :example_file:`protocols/l2tap/main/l2tap_main.c` + +.. only:: CONFIG_ESP_WIFI_SOFTAP_SUPPORT + + - Wi-Fi 接入点 :example_file:`wifi/getting_started/softAP/main/softap_example_main.c` + +更多示例请参阅 :doc:`/api-reference/network/esp_netif_driver`。 + + +.. only:: SOC_WIFI_SUPPORTED + + Wi-Fi 默认初始化 + ^^^^^^^^^^^^^^^^^^^^^^^^^^^ + + 初始化代码以及注册默认接口（例如接入点和基站）的事件处理程序都在单独的 API 中提供，以便为大多数应用程序提供简单的启动代码： + + * :cpp:func:`esp_netif_create_default_wifi_sta()` + + .. only:: CONFIG_ESP_WIFI_SOFTAP_SUPPORT + + * :cpp:func:`esp_netif_create_default_wifi_ap()` + + 注意，这些函数返回 ``esp_netif`` 句柄，即分配并配置了默认设置的网络接口对象的指针，这意味着： + + * 如果应用程序使用 :cpp:func:`esp_netif_destroy_default_wifi()` 提供网络去初始化，则创建的对象必须被销毁。 + + * 这些 *默认* 接口不能被多次创建，除非使用 :cpp:func:`esp_netif_destroy()` 删除已创建的句柄。 + + .. only:: CONFIG_ESP_WIFI_SOFTAP_SUPPORT + + * 在 ``AP+STA`` 模式下使用 Wi-Fi 时，须创建以上全部接口。 + + +API 参考 +------------- + +.. include-build-file:: inc/esp_netif.inc +.. include-build-file:: inc/esp_netif_sntp.inc +.. include-build-file:: inc/esp_netif_types.inc +.. include-build-file:: inc/esp_netif_ip_addr.inc +.. include-build-file:: inc/esp_vfs_l2tap.inc + + +.. only:: SOC_WIFI_SUPPORTED + + Wi-Fi 默认 API 参考 + ^^^^^^^^^^^^^^^^^^^^^^^^^^ + + .. include-build-file:: inc/esp_wifi_default.inc