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
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--- /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.