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## Release Notes

#### Boost 1.81

Features

- Add `buffers_generator`
- Add `http::message_generator`
- Add `buffer_ref`
- Support for per-operation cancellation

Fixes

- #2439 Fix CVE-2018-25032 in zlib streams
- #264 Websocket support continue in upgrade
- #471 Unquote takes s by reference

Improvements

- #2104 C++20 awaitable examples.
- #226, #227 per-message compression options
- #2449 websocket timeout option api
- #2468 multiple content length error

Miscellaneous

- Use `span` from Boost.Core
- Use `static_string` from Boost.StaticString
- `serializer::is_done` is `const`
- Support for default-completion and rebind
- #2469 s390x architecture support

Documentation

- #891 Feature table for buffers
- #516 Case-insensitivity for fields is stated
- #298 api version is documented

#### Boost 1.80

Miscellaneous

- #2363 Remove `BOOST_BEAST_USE_STD_STRING_VIEW`
- #2417 use boost::core::string_view. This improves inter-conversion between string_view implementations. Some observable differences for users:
  - `core::string_view` no longer supports the `.to_string()` or `.clear()` extensions from Utility
  - code that relied on `.max_size()` returning `.size(),` needs to be fixed to use `.size()` instead
  - `remove_suffix()` and `remove_prefix()` were more lenient than the standard specs; be sure you don't rely on it clamping the argument to valid range
  - `BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS` no longer suppresses conversions to `std::string`

#### Boost 1.79

Fixes

- #2391 Add missing include for file_body test.
- #2364 Fix WebSocket handshake response on failure.
- #2280 (related) Fix open append mode for file_posix.
- #2280 Fix open append mode for file_win32.
- #2280 Fix file open with append/append_existing flag on Windows
- #2354 Fix clang-cl UTF8 path handling for `file_win32`.
- #2354 Fix clang-cl UTF8 path handling for `file_stdio`.

Miscellaneous

- #2375 Add ARM64 builds to drone CI
- #2217 Fix async_base documentation link
- #2280 Add tests for file open in append/append_existing mode
- #2351 Update CI to include gcc 11, clang 12, msvc 14.3
- #2350 Add individual tests to CMake workflow

#### Boost 1.78

Fixes

- Fix CVE-2016-9840 in zlib implementation.
- Fix TLS SNI handling in websocket_client_async_ssl example.
- #2313 Fix reuse of sliding window in WebSocket permessage_deflate.
- Fix accept error handling in http_server_async example.

Miscellaneous

- Remove test framework's dependency on RTTI.
- Move library-specific docca configuration to Beast.
- Remove dependency on RTTI in `test::stream`.
- Fix missing includes in test headers.

#### Boost 1.77

Fixes

- #2233 Remove use of POSIX-only constant.

Miscellaneous

- Fixes to tests.
- Improvements and fixes in Github and Drone CI.
- Accommodate Docca updates.
- Update example root certificates.
- Add example of reading large response body.
- Remove Travis CI.
- Update CMakeLists.txt

#### Boost 1.76

Fixes

- #2139 Add executor rebind to test::stream.
- Fix unused variable compiler warning in WebSocket async shutdown.

Improvements

- #2124 Floating point support no longer required to use Beast.
- Reduce size of websockety compiled code by using a common buffers type for all operations.
- HTTP Parser has improved detection of incorrect use.

Miscellaneous

- #2140 Add cxxstd tag to library metadata.
- Move to Drone CI.
- Minor documentation formatting improvements.
- CML now finds required Boost::thread library during in-tree build.

#### Boost 1.75

Fixes

- Eliminate spurious unused parameter warning in `detect_ssl`.
- Update Websocket examples to set the SNI for TLS connections.
- #2023 websocket async_shutdown will now shutdown the underlying TLS transport.
- #2011 File open with append_existing flag now works correctly in posix environments.
- #2039 Windows builds now link to bcrypt as required by the filesystem library.
- #2063 Logic error fixed in `advanced_server_flex` example.
- #1582 Fix unreachable code error on MSVC.
- #2070 Fix http body behaviour when body_limit it none.
- #2065 Fix behaviour of `basic_stream` when a zero-length write is requested.
- #2080 Add enums representing Sec-* HTTP headers.
- #2085 Fix `nullptr` implicit cast on `fields::set()`.
- #2029 Fix C++20 tests for `basic_stream`.

Miscellaneous

- Add handler tracking to asynchronous operations:
  - Define the preprocessor macro `BOOST_ASIO_ENABLE_HANDLER_TRACKING` to enable Asio handler tracking in Boost.Beast asynchronous operations. Please see asio handler tracking for details.
- Add Bishop-Fox 2020 Security Assessment.

#### Boost 1.74

API Changes

- The API to Asio has undergone changes. Please refer to the Asio release notes for details.
- Beast has been updated to track and respect developer choices in the use of Asio. In particular:
  - Define `BOOST_ASIO_NO_DEPRECATED` to disallow deprecated invocation and allocation hooks.
  - Define `BOOST_ASIO_NO_TS_EXECUTORS` to ensure that executors conform to the Standard Executors proposal.
  - Define `BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT` to select Networking TS style executors by default. If this macro is not defined, Asio default executors will be the Standard Executors implementation.
- #1897 Parser `body_limit` is optional (API Change) Actions Required
  - The signature of `basic_parser<>::body_limit(n)` has changed. It now accepts an optional `std::uint64_t`. The caller may indicate that no body limit is required by calling `body_limit(boost::none)`. The default limits remain in place in order to maintain 'safe by default' behaviour.
- #1934 Remove deprecated interfaces (API Change) Actions Required
  - The macro `BOOST_BEAST_NO_DEPRECATED` will no longer be noticed by Beast. The only way to enable deprecated functionality is now the macro `BOOST_BEAST_ALLOW_DEPRECATED` which is undefined by default. That is, all deprecated behaviour is disabled by default.
  - The following deprecated functions have been removed:
    - `websocket::async_accept_ex`
    - `websocket::async_handshake_ex`
    - `websocket::accept_ex`
    - `websocket::handshake_ex` Programs still using these names should be refactored to use the `decorator` feature and the remaining handshake and accept functions.
  - `websocket::role_type` has been removed. Users should use `beast::role_type` instead.
  - `handler_ptr` has been removed. Users should use `net::bind_handler` and/or `bind_front_handler` instead.
  - Code that depends on `mutable_data_type` should be refactored to use `mutable_buffers_type`. Classes affected are:
    - `buffers_adaptor`
    - `flat_buffer`
    - `flat_static_buffer`
    - `multi_buffer`
    - `static_buffer`
  - The `reset` function has been removed from `flat_static_buffer`. Use the `clear` function instead.
  - The `core/type_traits.hpp` public header has been removed and along with it the type trait `is_completion_handler`. Beast uses the CompletionHandler correctness checks provided by Asio. In a c++20 environment, these convert to concept checks.
  - The error code enum `invalid_code_lenths` (sic) was a synonym of `invalid_code_lengths`. Affected programs should be modified to use `invalid_code_lengths`.
  - The file `core/buffers_adapter.hpp` has been removed along with the deprecated alias typename `buffers_adapter`. Affected programs should use `core/buffers_adapator.hpp` and the type `buffers_adaptor`.
- #1956 Deprecate `string_param` (API Change) Actions Required `string_param`, which was previously the argument type when setting field values has been replaced by `string_view`. Because of this, it is no longer possible to set message field values directly as integrals. Users are requied to convert numeric arguments to a string type prior to calling `fields::set` et. al. Beast provides the non-allocating `to_static_string()` function for this purpose. To set Content-Length field manually, call `message::content_length`.

Fixes

- #1913 Fix standalone compilation error with `std::string_view`
- #1925 #1916 Fix compile errors on Visual Studio with /std:c++latest
- #1924 Fix c++20 deprecation warning in `span_body`
- #1920 Fix use `buffered_read_stream` with `use_awaitable`
- #1918 Fix `async_detect_ssl` with `use_awaitable`
- #1944 Fix `FILE` namespace qualification
- #1942 Fix http read `bytes_transferred`
- #1943 Fix `basic_stream` `expires_after`
- #1980 Fix `max` compile error
- #1949 `iless` and `iequal` take part in Heterogeneous Lookup

Miscellaneous

- #1907 OpenSSL 1.0.2 or later is required when using SSL/TLS streams. This is a requirement inherited from Boost.Asio.
- Additional tests have been added to ensure correct integration with C++20 coroutines when avaialable.

#### Boost 1.73

API Changes

- Nested `mutable_data_type` in Beast dynamic buffers is deprecated. Affected types:
  - `buffers_adaptor`
  - `flat_buffer`
  - `flat_static_buffer`
  - `multi_buffer`
  - `static_buffer`

Changes Required

- Use nested `mutable_buffers_type` instead of `mutable_data_type`, or define `BOOST_BEAST_ALLOW_DEPRECATED`

Miscellaneous

- Update root certificates in examples

Fixes

- #1880 Fix Content-Length parsing
- #1852 Fix examples to dispatch to strand
- #1875 Ensure `basic_stream::close` will not throw
- #1863 Field digest is endian-independent
- #1853 Fix ostream flush
- #1831 `flat_buffer::shrink_to_fit` is `noexcept`
- #1828 Fix erase field
- #1822 Examples use strands correctly
- #1818 `file_body` returns `short_read` on eof during read
- #1786 Fix bug in win32 `file_body`
- #1260 Add accessor function to File member of `basic_file_body`
- #793 `file_win32` supports UTF-8 paths
- #793 `file_stdio` supports unicode paths
- #1786 `file_win32` bodies respect `http::serializer::split`
- Correct `buffer_bytes` documentation
- Fix missing include in sha1.hpp
- Fix ostream warning
- Update broken links in README
- Translate some win32 errors to net error codes
- Moved-from dynamic buffers do not clear if different allocator
- Fix compilation macro documentation
- Clarify end-of-file behaviour in `File::read` docs
- ostream_buffer satisfies preconditions of DynamicBuffer_v1::commit
- Fix release build of docs
- Fix `echo-op` test
- Fix non-msvc cmake

#### Boost 1.72

Examples

- Add async-ssl-system-executor http client example
- Add async-ssl-system-executor websocket client example

Features

- Async init-fns use the executor's default token
- Use automatically deduced return types for all async operations (since C++14)
- Support Concepts for completion token params

Fixes

- #1664 Add default dtors to satisfy -Wnon-virtual-dtor
- #1682 Multiple I/O of the same type is not supported
- #1687 Fix signed/unsigned mismatch in file_stdio::seek
- #1688 basic_stream dtor cannot throw
- #1734 Fix leftovers in basic_parser corner case:
- #1751 https_get example sends the Host header
- #1754 Fix async_close error code when async_read times out
- #1782 root_certificates.hpp is not for production
- Fix data race in websocket examples
- Fix data race in http server examples
- Squelch spurious websocket timer assert
- Use the executor type in basic_stream timer

#### Boost 1.71

Improvements

- #1280 Add 1-element specialization for `buffers_cat`
- #1556 Set parser status and flags even if body limit has been reached
- #1567 Relax requirements for vector_body
- #1568 `detect_ssl` uses `bool` instead of `tribool`
- #1574 Replace `static_string` in HTTP parser
- #1606 Use `steady_timer` type
- #1611 Make chat websocket javascript client more user friendly
- #1613 Remove redundant use of `static_string`
- #1636 Improve performance of `http::string_to_verb`
- Preserve `operation_aborted` on partial message
- Remove unused `<experimental/unit_test/thread.hpp>`
- Reduce the number of instantiations of `filter_token_list`
- Add idle ping suspend test
- Remove the use of `bind_executor` in `basic_stream`
- Remove redundant template in service_base
- Remove the use of `static_string` from `http::fields`
- Enable split compilation in http::basic_fields
- Remove redundant instation of `static_string` in websocket
- Remove redundant use of `asio::coroutine` in `flat_stream`
- More split compilation in rfc7230.hpp
- More split compilation in websocket/detail/mask.hpp
- Simplify generation of sec-websocket-key

Fixes

- #1332 `allocator_traits::construct` is used for user-defined types
- #1559 Member `get_executor` const-correctness
- #1569 Fix `async_detect_ssl` handler type
- #1570 Launder pointers
- #1578 Fix min/max on MSVC
- #1586 Fix uninitalized memory use in deflate_stream
- #1593 Fix UB in websocket close tests
- #1594 Fix data race in test stream
- #1599 Fix moved-from executor in idle ping timeout
- #1607 Remove uses of the deprecated `buffers` function
- #1612 Remove uses of deprecated methods in websocket tests
- #1620 Clean up typo in chat websocket javascript client
- #1621 Fix `flat_buffer` copy members
- Silence gcc-8 warning
- Fix `buffers_cat` iterator tests
- Don't pessimize-move
- Qualify calls to `beast::iequals` in basic_parser.ipp
- Fix UB in websocket read tests
- Simplify websocket::detail::prng
- Don't over-allocate in http::basic_fields

Documentation

- Documentation is built with SaxonHE instead of xsltproc

#### Boost 1.70

| Tip
The namespace alias `net` is used throughout for `boost::asio`.

New Features

- All composed operations use the new `net::async_initiate` internally.
- New `tcp_stream` and `basic_stream` support:
  - Timeouts, `async_read_some`, `async_write_some` complete with `error::timeout` on expiration.
  - Traffic-shaping policies `simple` and `unlimited`, or a user-defined RatePolicy.
  - Supports P1322R0.
- `websocket::stream` supports
  - Configurable handshake timeout
  - Configurable idle timeout
  - Automatic idle pings
- `ssl_stream` is a public interface
- ( #1305) Better `flat_buffer`, `flat_static_buffer`, `multi_buffer`, and `static_buffer`:
  - Revise all reference documentation
  - Move construction does not always invalidate buffers
  - non-const `data()` returns a mutable buffer sequence
  - Add `cdata()` to also return constant readable bytes
  - Eligible member functions are declared `noexcept`
- ( #1345) Better `flat_buffer`, `multi_buffer`
  - Add `clear`, `reserve()`, `max_size()`, `shrink_to_fit()`
  - Respect Allocator `max_size()`
  - Specify exception safety
- ( #1384) New functions `bind_front_handler`
- Better `static_buffer`, `flat_static_buffer`
  - Add `clear()`
  - More members are `noexcept`
  - Specify exception safety
- Faster `http::string_to_field`
- Dynamic buffer `clear` operations perserve capacity.
- New file <boost/beast/core/buffer_traits.hpp>
  - New variadic `is_const_buffer_sequence`
  - New variadic `is_mutable_buffer_sequence`
  - New trait `buffers_iterator_type`
  - New trait `buffers_type`
- New classes `async_base`, `stable_async_base`
  - Handle boilerplate for writing composed operations
  - New `allocate_stable` is preferred over `handler_ptr`
- New `buffer_bytes` replacement for `net::buffer_size`
- New:
  - `saved_handler`
  - `buffers_range_ref`
  - `executor_type`
  - `get_lowest_layer`, `lowest_layer_type`
  - `close_socket`, `beast_close_socket`
  - `error`, `condition`
- These interfaces are now public (were experimental): `flat_stream`, `detect_ssl`, `async_detect_ssl`.
- Websocket streams use PCG as the fast random number generator, for increased security.

Documentation

- WebSocket reference documentation is revised
- Updated Networking Refresher
- Revised Asynchronous Echo
- Rewritten Detect SSL Handshake

API Changes

- The Fields concept is deprecated and will be removed in a future version. Actions Required: Do not rely on the Fields concept.
- `handler_ptr` is deprecated. Actions Required: Use `stable_async_base` and `allocate_stable` instead.
- On Windows, Visual Studio 2017 or later is required
- OpenSSL is required to build the examples and tests
- HTTP stream algorithms return the number of bytes transferred from the stream. Previously, they returned the number of bytes consumed by the parser. Actions Required:
  - Callers depending on the return value of `http::read` or `http::async_read` overloads should adjust the usage of the returned value as needed.
- Metafunctions `has_get_executor`, `is_sync_stream`, `is_sync_read_stream`, `is_sync_write_stream`, `is_async_stream`, `is_async_read_stream`, and `is_async_write_stream` are in stream_traits.hpp. Actions Required: Include stream_traits.hpp as needed.
- `basic_parser` is abstract. Actions Required
  - Change uses of the `basic_parser` type to omit the `Derived` template parameter
  - Classes derived from `basic_parser` no longer need to friend the base.
  - Virtual functions in the derived class may be marked `override`.
- Metafunction `is_file` is in file_base.hpp. Actions Required: Include file_base.hpp as needed.
- `flat_static_buffer::reset()` is deprecated. Actions Required:
  - call `clear()` instead.
- `buffers_adapter` is spelled `buffers_adaptor`. Actions Required:
  - Replace `buffers_adapter` with `buffers_adaptor`, or define `BOOST_BEAST_ALLOW_DEPRECATED`.
- `buffers` is spelled `make_printable`. Actions Required:
  - Replace `buffers` with `make_printable`, and include "make_printable.hpp" instead of "ostream.hpp".
- `file_mode::append_new` is removed, as it makes no sense. Actions Required:
  - Replace `file_mode::append_new` with either `file_mode::append` or `file_mode::append_existing` as needed.
- `role_type` is moved from `websocket` to `beast`
- `buffers_range_ref` is preferred to `std::reference_wrapper`. Actions Required:
  - Call `buffers_range_ref` with the buffer, instead of calling `buffers_range` with a reference wrapper constructed from the buffer.
- Nested `lowest_layer` and `lowest_layer_type` are removed. Actions Required: Use the free function `get_lowest_layer` and the type trait `lowest_layer_type` instead.
- WebSocket decorator is a socket option:
  - Overloads of the following functions which accept a Decorator are deprecated:
    - `accept`, `accept_ex`
    - `handshake`, `handshake_ex`
    - `async_accept`, `async_accept_ex`
    - `async_handshake`, `async_handshake_ex`
- ( #1375) The value returned from `basic_parser::content_length` no longer changes as the body of the message is received. Actions Required: Call `basic_parser::content_length_remaining` instead of `basic_parser::content_length` in order to determine the remaining number of bytes in the body.

Examples

- All example programs are updated:
  - Use `tcp_stream` with timeouts (HTTP)
  - Use `ssl_stream`
  - Set timeouts for WebSocket streams.
  - Use `bind_front_handler`
- ( #1100) http-crawl clears the response before each read
- ( #1347) echo-op is rewritten
- ( #1401) Examples use `flat_buffer`
- Advanced servers use HTTP parser interfaces for reading
- detect-ssl is rewritten
- New example example/websocket/server/chat-multi
- `async_echo` works with move-only handlers
- cppcon2018 example is removed

Fixes

- ( #38) Better treatment of SSL short reads
- ( #1223) HTTP read counts bytes correctly when an error occurs
- ( #1247) Update `ssl_stream` for Asio changes
- ( #1279) Enable explicit instantiations of `websocket::stream`
- ( #1290) Don't use deprecated Asio interfaces
- ( #1306) `http::message` is not-a `boost::empty_value`
- ( #1306) `test::stream` has fewer dependencies
- ( #1358) Destroy abandoned websocket ops on shutdown
- ( #1365) Handler wrappers decay parameters sooner
- ( #1408) `session_alloc` is thread-safe
- ( #1414) Boost.System is header-only
- ( #1418) `test::stream` maintains a handler work guard
- ( #1445) Fix posix_file::close handling of EINTR
- ( #1460) Large WebSocket Upgrade response no longer overflows
- Reusing an HTTP parser returns an error
- Handler bind wrappers use the associated allocator
- `buffers_cat` correctly skips empty buffers when iterated
- `ostream` does not overflow or exceed the dynamic buffer's maximum size
- Fixes to `test::stream::async_read`
- `file_mode::append_existing` works correctly
- A handler work guard is maintained on paused websocket operations
- All behavior of default-constructed iterators is conforming

#### Boost 1.69

New Videos

New Features

- ( #1133) Add `BOOST_BEAST_USE_STD_STRING_VIEW`

Examples

- New WebSocket server and browser-based client: example/cppcon2018

Fixes

- ( #1245) Fix a rare case of incorrect UTF8 validation
- ( #1237) Verify certificates in client examples
- ( #1233) Use `boost::empty_value`
- ( #1091) Fix timer on websocket upgrade in examples
- ( #1270) `basic_fields` uses intrusive base hooks
- ( #1267) Fix parsing of out-of-bounds hex values
- ( #1263) Fix uninitialized comparison in buffers iterator
- ( #1288) Remove extraneous strand from example
- Workaround for http-server-fast and libstdc++
- Partial support for `BOOST_NO_EXCEPTIONS`

Experimental

- Add `timeout_socket`

#### Boost 1.68

This version fixes a missing executor work guard in all composed operations used in the implementation. Users who are experiencing crashes related to asynchronous completion handlers are encouraged to upgrade. Also included is an improved mechanism for generating random numbers used to mask outgoing websocket frames when operating in the client mode. This resolves a vulnerability described in the Beast Hybrid Assessment Report from Bishop Fox.

New Features

The include directory `<beast/experimental>` contains features which are not part of the stable public interface but are available anyway. They may change in future versions.

- ( #1108) New `flat_stream` for working around an SSL stream performance limitation
- ( #1151, #595) New `http::icy_stream` stream filter allows parsing ICY HTTP response handshakes
- New `ssl_stream` for better SSL performance and move constructability
- New `test::connect`, `test::error`, `test::fail_count`, and `test::stream` utilities for writing unit tests.
- New `http::is_mutable_body_writer` metafunction
- New `websocket::seed_prng` for manually providing entropy to the PRNG
- New `websocket::stream::secure_prng` to control whether the connection uses a secure PRNG

Improvements

- Generated WebSocket masks use a secure PRNG by default
- Improvements to `buffers_adaptor`
- ( #1188) Set "/permissive-" for MSVC builds
- ( #1109) Use a shared string for example HTTP server doc roots
- ( #1079) Add `handler_ptr::has_value`

Fixes

- ( #1073) Fix race in advanced server examples
- ( #1076) Use executor_work_guard in composed operations
- ( #1079) Remove spurious assert
- ( #1113) Add `const` and non-`const` overloads for message based HTTP writes
- ( #1119) Fix unused variable warning
- ( #1121) Examples use the root certificate which matches the fingerprint
- ( #1141) Tidy up composed operation doc
- ( #1186) Check error in example set_option
- ( #1210) Fix http_server_stackless_ssl.cpp example
- ( #1211) Fix parse_dec algorithm
- ( #1214) Silence ubsan false positive
- Tidy up websocket stream javadocs
- Fix move-only arguments in `bind_handler`
- Fix `http::parser` constructor javadoc
- Fix `buffers_adaptor` iterator value type
- Fix `buffers_adaptor::max_size`
- Fix `buffers_prefix` iterator decrement
- Fix Fields, FieldsWriter concept docs
- Fix BodyReader constructor requirements doc

Breaking Changes

- Remove deprecated `serializer::reader_impl`
- Remove deprecated Body `reader` and `writer` ctor signatures

#### Boost 1.67

This version fixes significant defects in `websocket::stream` which can lead to asserts or undefined behavior. Users are encouraged to update to the latest Boost release.

New Features

- Move-only completion handlers are supported throughout the library
- ( #899) Advanced server examples support idle websocket pings and timeouts
- ( #849) WebSocket permessage-deflate support is now a compile-time feature. This adds an additional `bool` template parameter to `websocket::stream` When `deflateSupported` is `true`, the stream will be capable of negotiating the permessage-deflate websocket extension per the configured run-time settings. When `deflateSupported` is `false`, the stream will never negotiate the permessage-deflate websocket extension. Furthermore, all of the code necessary for implementing the permessage-deflate extension will be excluded from function instantiations. Programs which set `deflateSupported` to `false` when instantiating streams will be smaller.
- ( #949) WebSocket error codes are revised. New error codes are added for more fine-grained failure outcomes. Messages for error codes are more verbose to help pinpoint the problem. Error codes are now also mapped to newly added error conditions to simplify comparisons. The error codes `websocket::error::failed` and `websocket::error::handshake_failed` are removed. Actions required: Code which explicitly compares `error_code` values against the constant `websocket::error::handshake_failed` should compare against `websocket::condition::handshake_failed` instead. Code which explicitly compares error_code values against the constant `websocket::error::failed` should compare against `websocket::condition::protocol_violation` instead.

Improvements

- ( #857) `http::basic_fields` uses less storage
- ( #894) `http::basic_fields` exception specifiers are provided
- Implementation no longer uses deprecated `asio::null_buffers`
- Add `<boost/beast/websocket/stream_fwd.hpp>`
- ( #955) The asynchronous SSL detector example uses a stackless coroutine
- `bind_handler` works with boost placeholders
- Examples set `reuse_address(true)`
- ( #1026) Advanced servers support clean shutdown via SIGINT or SIGTERM
- Some basic_fields operations now give the strong exception guarantee

Fixes

- Fix "warning: ‘const’ type qualifier on return type has no effect"
- ( #916) Tidy up `ssl_stream` special members
- ( #918) Calls to `<algorithm>` are protected from macros
- ( #954) The control callback is invoked on the proper executor
- ( #994) Fix iterator version of `http::basic_fields::erase`
- ( #992) Fix use-after-move in example request handlers
- ( #988) Type check completion handlers
- ( #985) Tidy up `bind_handler` doc
- Fix memory leak in advanced server examples
- ( #1000) Fix soft-mutex assert in websocket stream. This resolves the assert `"ws_.wr_block_ == tok_"`.
- ( #1019) Fix fallthrough warnings
- ( #1024) Fix teardown for TIME_WAIT
- ( #1030) Fix big-endian websocket masking
- Safe treatment of zero-length string arguments in basic_fields
- ( #1043) Examples clear the HTTP message before reading
- ( #1012) Add asio_handler_invoke overloads for stream algorithms
- Add Access-Control-Expose-Headers field constant

API Changes

- Remove unintended public members of `handler_ptr`. Actions required: don't call non-public members.
- `handler_ptr` is a move-only type, with `unique_ptr` semantics. Actions required: user-defined composed operations using `handler_ptr` to manage state can only be moved, not copied.
- `handler_ptr` gives the strong exception guarantee. The constructor signature for managed objects constructed by `handler_ptr` now receives a `const` reference to the handler. Actions required: Change the constructor signature for state objects used with `handler_ptr` to receive a `const` reference to the handler.
- ( #896) `http::basic_fields` does not support fancy pointers
- `http::parser` is no longer MoveConstructible
- ( #930) `http::serializer::reader_impl` is deprecated and will be removed in the next release. Actions required: Call `http::serializer::writer_impl` instead of `serializer::reader_impl`.
- ( #884) The BodyReader and BodyWriter concept constructor requirements have changed. They now require the header and body elements to be passed as distinct `http::header` and `value_type` objects. This enables the composition of body types. The previous single-argument constructors are deprecated and will be removed in the next version. Actions required: Change user-defined instances of BodyReader or BodyWriter constructor signatures to the two-argument form. Alternatively. define the macro `BOOST_BEAST_ALLOW_DEPRECATED` in the project (which will cause both the new and the deprecated signatures to be accepted).
- `websocket::stream::control_callback` now copies or moves the function object.
- ( #1014) DynamicBuffer input areas are not mutable. Actions required: do not attempt to write to input areas of dynamic buffers.
- ( #941) `get_lowest_layer` is now a type alias. Actions required: Replace instances of `typename get_lowest_layer<T>::type` with `get_lowest_layer<T>`.

#### Boost 1.66

- Initial release