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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 07:32:08 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 07:32:08 +0000 |
commit | 328ad0a41c6bdf596224ff2e9ab9c0fabde8634d (patch) | |
tree | 973585a56cea8664b4be63b5bb737b443e4e2b76 /doc/source | |
parent | Initial commit. (diff) | |
download | nghttp3-upstream/0.8.0.tar.xz nghttp3-upstream/0.8.0.zip |
Adding upstream version 0.8.0.upstream/0.8.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/source')
-rw-r--r-- | doc/source/.gitignore | 5 | ||||
-rw-r--r-- | doc/source/conf.py.in | 94 | ||||
-rw-r--r-- | doc/source/index.rst | 22 | ||||
-rw-r--r-- | doc/source/programmers-guide.rst | 207 | ||||
-rw-r--r-- | doc/source/qpack-howto.rst | 85 |
5 files changed, 413 insertions, 0 deletions
diff --git a/doc/source/.gitignore b/doc/source/.gitignore new file mode 100644 index 0000000..a1a2e88 --- /dev/null +++ b/doc/source/.gitignore @@ -0,0 +1,5 @@ +/conf.py +/apiref.rst +/enums.rst +/macros.rst +/types.rst diff --git a/doc/source/conf.py.in b/doc/source/conf.py.in new file mode 100644 index 0000000..171595f --- /dev/null +++ b/doc/source/conf.py.in @@ -0,0 +1,94 @@ +# nghttp3 + +# Copyright (c) 2020 nghttp3 contributors + +# Permission is hereby granted, free of charge, to any person obtaining +# a copy of this software and associated documentation files (the +# "Software"), to deal in the Software without restriction, including +# without limitation the rights to use, copy, modify, merge, publish, +# distribute, sublicense, and/or sell copies of the Software, and to +# permit persons to whom the Software is furnished to do so, subject to +# the following conditions: + +# The above copyright notice and this permission notice shall be +# included in all copies or substantial portions of the Software. + +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE +# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + +# Configuration file for the Sphinx documentation builder. +# +# This file only contains a selection of the most common options. For a full +# list see the documentation: +# https://www.sphinx-doc.org/en/master/usage/configuration.html + +# -- Path setup -------------------------------------------------------------- + +# If extensions (or modules to document with autodoc) are in another directory, +# add these directories to sys.path here. If the directory is relative to the +# documentation root, use os.path.abspath to make it absolute, like shown here. +# +# import os +# import sys +# sys.path.insert(0, os.path.abspath('.')) + + +# -- Project information ----------------------------------------------------- + +project = 'nghttp3' +copyright = '2020, nghttp3 contributors' +author = 'nghttp3 contributors' + + +# -- General configuration --------------------------------------------------- + +# Add any Sphinx extension module names here, as strings. They can be +# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom +# ones. +extensions = [ +] + +# Add any paths that contain templates here, relative to this directory. +templates_path = ['_templates'] + +# List of patterns, relative to source directory, that match files and +# directories to ignore when looking for source files. +# This pattern also affects html_static_path and html_extra_path. +exclude_patterns = [] + + +# -- Options for HTML output ------------------------------------------------- + +# The theme to use for HTML and HTML Help pages. See the documentation for +# a list of builtin themes. +# +html_theme = 'alabaster' + +# Add any paths that contain custom static files (such as style sheets) here, +# relative to this directory. They are copied after the builtin static files, +# so a file named "default.css" will overwrite the builtin "default.css". +html_static_path = ['_static'] + +# The reST default role (used for this markup: `text`) to use for all documents. +default_role = 'c:func' +primary_domain = 'c' + +# manpage URL pattern +manpages_url = 'https://man7.org/linux/man-pages/man{section}/{page}.{section}.html' + +# The default language to highlight source code in. +highlight_language = 'c' + +# The version info for the project you're documenting, acts as replacement for +# |version| and |release|, also used in various other places throughout the +# built documents. +# +# The short X.Y version. +version = '@PACKAGE_VERSION@' +# The full version, including alpha/beta/rc tags. +release = '@PACKAGE_VERSION@' diff --git a/doc/source/index.rst b/doc/source/index.rst new file mode 100644 index 0000000..2ba7331 --- /dev/null +++ b/doc/source/index.rst @@ -0,0 +1,22 @@ +.. nghttp3 documentation master file, created by + sphinx-quickstart on Mon Nov 30 22:15:12 2020. + You can adapt this file completely to your liking, but it should at least + contain the root `toctree` directive. + +Welcome to nghttp3's documentation! +=================================== + +.. toctree:: + :maxdepth: 1 + :caption: Contents: + + programmers-guide + qpack-howto + apiref + +Indices and tables +================== + +* :ref:`genindex` +* :ref:`modindex` +* :ref:`search` diff --git a/doc/source/programmers-guide.rst b/doc/source/programmers-guide.rst new file mode 100644 index 0000000..d47d19c --- /dev/null +++ b/doc/source/programmers-guide.rst @@ -0,0 +1,207 @@ +The nghttp3 programmers' guide +============================== + +This document describes a basic usage of nghttp3 library and common +pitfalls which programmers might encounter. + +Assumptions +----------- + +nghttp3 is a thin HTTP/3 layer over an underlying QUIC stack. It +relies on an underlying QUIC stack for flow control and connection +management. Although nghttp3 is QUIC stack agnostic, it expects some +particular interfaces from QUIC stack. We will describe them below. + +QPACK operations are done behind the scenes. Application can use +:type:`nghttp3_settings` to change the behaviour of QPACK +encoder/decoder. + +We define some keywords to avoid ambiguity in this document: + +* HTTP payload: HTTP request/response body +* HTTP stream data: Series of HTTP header fields, HTTP payload, and + HTTP trailer fields, serialized into HTTP/3 wire format, which is + passed to or received from QUIC stack. + +Initialization +-------------- + +The :type:`nghttp3_conn` is a basic building block of nghttp3 library. +It is created per HTTP/3 connection. If an endpoint is a client, use +`nghttp3_conn_client_new` to initialize it as client. If it is a +server, use `nghttp3_conn_server_new` to initialize it as server. + +Those initialization functions take :type:`nghttp3_callbacks`. All +callbacks are optional, but setting no callback functions makes +nghttp3 library useless for the most cases. We list callbacks which +effectively required to do HTTP/3 transaction below: + +* :member:`acked_stream_data <nghttp3_callbacks.acked_stream_data>`: + Application has to retain HTTP payload (HTTP request/response body) + until they are no longer used by :type:`nghttp3_conn`. This + callback functions tells the largest offset of HTTP payload + acknowledged by a remote endpoint, and no longer used. +* :member:`stream_close <nghttp3_callbacks.stream_close>`: It is + called when a stream is closed. It is useful to free resources + allocated for a stream. +* :member:`recv_data <nghttp3_callbacks.recv_data>`: It is called when + HTTP payload (HTTP request/response body) is received. +* :member:`deferred_consume <nghttp3_callbacks.deferred_consume>`: It + is called when :type:`nghttp3_conn` consumed HTTP stream data which + had been blocked for synchronization between streams. Application + has to tell QUIC stack the number of bytes consumed which affects + flow control. We will discuss more about this callback later when + explaining `nghttp3_conn_read_stream`. +* :member:`recv_header <nghttp3_callbacks.recv_header>`: It is called + when an HTTP header field is received. +* :member:`send_stop_sending <nghttp3_callbacks.send_stop_sending>`: + It is called when QUIC STOP_SENDING frame must be sent for a + particular stream. Sending STOP_SENDING frame means that + :type:`nghttp3_conn` no longer reads an incoming data for a + particular stream. Application has to tell QUIC stack to send + STOP_SENDING frame. +* :member:`reset_stream <nghttp3_callbacks.reset_stream>`: It is + called when QUIC RESET_STREAM frame must be sent for a particular + stream. Sending RESET_STREAM frame means that :type:`nghttp3_conn` + stops sending any HTTP stream data to a particular stream. + Application has to tell QUIC stack to send RESET_STREAM frame. + +The initialization functions also takes :type:`nghttp3_settings` which +is a set of options to tweak HTTP3/ connection settings. +`nghttp3_settings_default` fills the default values. + +The *user_data* parameter to the initialization function is an opaque +pointer and it is passed to callback functions. + +Binding control streams +----------------------- + +HTTP/3 requires at least 3 local unidirectional streams for a control +stream and QPACK encoder/decoder streams. + +Use the following functions to bind those streams to their purposes: + +* `nghttp3_conn_bind_control_stream`: Bind a given stream ID to a HTTP + control stream. +* `nghttp3_conn_bind_qpack_streams`: Bind given 2 stream IDs to QPACK + encoder and decoder streams. + +Reading HTTP stream data +------------------------ + +`nghttp3_conn_read_stream` reads HTTP stream data from a particular +stream. It returns the number of bytes "consumed". "Consumed" means +that the those bytes are completely processed and QUIC stack can +increase the flow control credit of both stream and connection by that +amount. + +The HTTP payload notified by :member:`nghttp3_callbacks.recv_data` is +not included in the return value. This is because the consumption of +those data is done by application and nghttp3 library does not know +when that happens. + +Some HTTP stream data might be consumed later because of +synchronization between streams. In this case, those bytes are +notified by :member:`nghttp3_callbacks.deferred_consume`. + +In every case, the number of consumed HTTP stream data must be +notified to QUIC stack so that it can extend flow control limits. + +Writing HTTP stream data +------------------------ + +`nghttp3_conn_writev_stream` writes HTTP stream data to a particular +stream. The order of streams to produce HTTP stream data is +determined by the nghttp3 library. In general, the control streams +have higher priority. The regular HTTP streams are ordered by +header-based HTTP priority (see +https://tools.ietf.org/html/draft-ietf-httpbis-priority-03). + +When HTTP stream data is generated, its stream ID is assigned to +*\*pstream_id*. The pointer to HTTP stream data is assigned to *vec*, +and the function returns the number of *vec* it filled. If the +generated data is the final part of the stream, *\*pfin* gets nonzero +value. If no HTTP stream data is generated, the function returns 0 +and *\*pstream_id* gets -1. + +The function might return 0 and *\*pstream_id* has proper stream ID +and *\*pfin* set to nonzero. In this case, no data is written, but it +signals the end of the stream. Even though no data is written, QUIC +stack should be notified of the end of the stream. + +The produced HTTP stream data is passed to QUIC stack. Then call +`nghttp3_conn_add_write_offset` with the number of bytes accepted by +QUIC stack. This must be done even when the written data is 0 bytes +with fin (refer to the previous paragraph for this corner case). + +If QUIC stack indicates that a stream is blocked by stream level flow +control limit, call `nghttp3_conn_block_stream`. It makes the library +not to generate HTTP stream data for the stream. Call +`nghttp3_conn_unblock_stream` when stream level flow control limit is +increased. + +If QUIC stack indicates that the write side of stream is closed, call +`nghttp3_conn_shutdown_stream_write` instead of +`nghttp3_conn_block_stream` so that the stream never be scheduled in +the future. + +Creating HTTP request or response +--------------------------------- + +In order to create HTTP request, client application calls +`nghttp3_conn_submit_request`. :type:`nghttp3_data_reader` is used to +send HTTP payload (HTTP request body). + +Similarly, server application calls `nghttp3_conn_submit_response` to +create HTTP response. :type:`nghttp3_data_reader` is also used to +send HTTP payload (HTTP response body). + +In both cases, if :type:`nghttp3_data_reader` is not provided, no HTTP +payload is generated. + +The :member:`nghttp3_data_reader.read_data` is a callback function to +generate HTTP payload. Application must retain the data passed to the +library until those data are acknowledged by +:member:`nghttp3_callbacks.acked_stream_data`. When no data is +available but will become available in the future, application returns +:macro:`NGHTTP3_ERR_WOULDBLOCK` from this callback. Then the callback +is not called for the particular stream until +`nghttp3_conn_resume_stream` is called. + +Reading HTTP request or response +-------------------------------- + +The :member:`nghttp3_callbacks.recv_header` is called when an HTTP +header field is received. + +The :member:`nghttp3_callbacks.recv_data` is called when HTTP payload +is received. + +Acknowledgement of HTTP stream data +----------------------------------- + +QUIC stack must provide an interface to notify the amount of data +acknowledged by a remote endpoint. `nghttp3_conn_add_ack_offset` must +be called with the largest offset of acknowledged HTTP stream data. + +Handling QUIC stream events +--------------------------- + +If underlying QUIC stream is closed, call `nghttp3_conn_close_stream`. + +If underlying QUIC stream is reset by a remote endpoint (that is when +RESET_STREAM is received) or no longer read by a local endpoint (that +is when STOP_SENDING is sent), call +`nghttp3_conn_shutdown_stream_read`. + +Closing HTTP/3 connection gracefully +------------------------------------ + +`nghttp3_conn_submit_shutdown_notice` creates a message to a remote +endpoint that HTTP/3 connection is going down. The receiving endpoint +should stop sending HTTP request after reading this signal. After a +couple of RTTs, call `nghttp3_conn_submit_shutdown` to start graceful +shutdown. After calling this function, the local endpoint starts +rejecting new incoming streams. The existing streams are processed +normally. When all those streams are completely processed, the +connection can be closed. diff --git a/doc/source/qpack-howto.rst b/doc/source/qpack-howto.rst new file mode 100644 index 0000000..a38d285 --- /dev/null +++ b/doc/source/qpack-howto.rst @@ -0,0 +1,85 @@ +QPACK How-To +============ + +Using QPACK encoder +------------------- + +Firstly, create QPACK encoder by calling `nghttp3_qpack_encoder_new`. +It requires *hard_max_dtable_size* parameter. When in doubt, pass +4096 for this tutorial. Optionally, call +`nghttp3_qpack_encoder_set_max_dtable_capacity` to set the maximum +size of dynamic table. You can also call +`nghttp3_qpack_encoder_set_max_blocked_streams` to set the maximum +number of streams that can be blocked. + +In order to encode HTTP header fields, they must be stored in an array +of :type:`nghttp3_nv`. Then call `nghttp3_qpack_encoder_encode`. It +writes 3 buffers; *pbuf*, *rbuf*, and *ebuf*. They are a header block +prefix, request stream, and encoder stream respectively. A header +block prefix and request stream must be sent in this order to a stream +denoted by *stream_id* passed to the function. Encoder stream must be +sent to the encoder stream you setup. + +In order to read decoder stream, call +`nghttp3_qpack_encoder_read_decoder`. + +Once QPACK encoder is no longer used, call `nghttp3_qpack_encoder_del` +to free up memory allocated for it. + +Using QPACK decoder +------------------- + +`nghttp3_qpack_decoder_new` will create new QPACK decoder. It +requires *hard_max_dtable_size* and *max_blocked* parameters. When in +doubt, pass 4096 and 0 respectively for this tutorial. + +In order to read encoder stream, call +`nghttp3_qpack_decoder_read_encoder`. This might update dynamic +table, but does not emit any header fields. + +In order to read request stream, call +`nghttp3_qpack_decoder_read_request`. This is the function to emit +header fields. *sctx* stores a per-stream decoder state and must be +created by `nghttp3_qpack_stream_context_new`. It identifies a single +encoded header block in a particular request stream. *fin* must be +nonzero if and only if a passed data contains the last part of encoded +header block. + +The scope of :type:`nghttp3_qpack_stream_context` is per header block, +but `nghttp3_qpack_stream_context_reset` resets its state and can be +reused for an another header block in the same stream. In general, +you can reset it when you see that +:macro:`NGHTTP3_QPACK_DECODE_FLAG_FINAL` is set in *\*pflags*. When +:type:`nghttp3_qpack_stream_context` is no longer necessary, call +`nghttp3_qpack_stream_context_del` to free up its resource. + +`nghttp3_qpack_decoder_read_request` succeeds, *\*pflags* is assigned. +If it has :macro:`NGHTTP3_QPACK_DECODE_FLAG_EMIT` set, a header field +is emitted and stored in the buffer pointed by *nv*. If *\*pflags* +has :macro:`NGHTTP3_QPACK_DECODE_FLAG_FINAL` set, all header fields +have been successfully decoded. If *\*pflags* has +:macro:`NGHTTP3_QPACK_DECODE_FLAG_BLOCKED` set, decoding is blocked +due to required insert count, which means that more data must be read +by `nghttp3_qpack_decoder_read_encoder`. + +`nghttp3_qpack_decoder_read_request` returns the number of bytes read. +When a header field is emitted, it might read data partially. +Applciation has to call the function repeatedly by adjusting the +pointer to data and its length until the function consumes all data or +:macro:`NGHTTP3_QPACK_DECODE_FLAG_BLOCKED` is set in *\*pflags*. + +If *nv* is assigned, its :member:`nv->name <nghttp3_qpack_nv.name>` +and :member:`nv->value <nghttp3_qpack_nv.value>` are reference counted +and already incremented by 1. If application finishes processing +these values, it must call `nghttp3_rcbuf_decref(nv->name) +<nghttp3_rcbuf_decref>` and `nghttp3_rcbuf_decref(nv->value) +<nghttp3_rcbuf_decref>`. + +If an application has no interest to decode header fields for a +particular stream, call `nghttp3_qpack_decoder_cancel_stream`. + +In order to tell decoding state to an encoder, QPACK decoder has to +write decoder stream by calling `nghttp3_qpack_decoder_write_decoder`. + +Once QPACK decoder is no longer used, call `nghttp3_qpack_decoder_del` +to free up memory allocated for it. |