add zstd decoder

CMakeLists.txt

@@ -193,6 +193,33 @@ if (Libpsl_FOUND)
     target_compile_definitions(boost_burl PRIVATE BOOST_BURL_HAS_LIBPSL)
 endif ()
 
+#-------------------------------------------------
+#
+# Compression backends (optional)
+#
+#-------------------------------------------------
+
+# zlib: deflate and gzip content codings
+find_package(ZLIB)
+if (ZLIB_FOUND)
+    target_link_libraries(boost_burl PRIVATE ZLIB::ZLIB)
+    target_compile_definitions(boost_burl PUBLIC BOOST_BURL_HAS_ZLIB)
+endif ()
+
+# Brotli: br content coding (decoding only)
+find_package(Brotli)
+if (Brotli_FOUND)
+    target_link_libraries(boost_burl PRIVATE Brotli::common Brotli::decoder)
+    target_compile_definitions(boost_burl PUBLIC BOOST_BURL_HAS_BROTLI)
+endif ()
+
+# Zstandard: zstd content coding
+find_package(Zstd)
+if (Zstd_FOUND)
+    target_link_libraries(boost_burl PRIVATE Zstd::Zstd)
+    target_compile_definitions(boost_burl PUBLIC BOOST_BURL_HAS_ZSTD)
+endif ()
+
 #-------------------------------------------------
 #
 # Tests

build/Jamfile

@@ -12,6 +12,7 @@ import config : requires ;
 
 using openssl ;
 using zlib ;
+using brotli ;
 using zstd ;
 
 constant c11-requires :
@@ -40,8 +41,9 @@ lib boost_burl
      <library>/boost//capy
      <library>/boost//corosio
      [ ac.check-library /boost/corosio//boost_corosio_openssl : <library>/boost/corosio//boost_corosio_openssl : ]
-     [ ac.check-library /zlib//zlib : <library>/zlib//zlib : ]
-     [ ac.check-library /zstd//zstd : <library>/zstd//zstd : ]
+     [ ac.check-library /zlib//zlib : <library>/zlib//zlib <define>BOOST_BURL_HAS_ZLIB : ]
+     [ ac.check-library /brotli//brotlidec : <library>/brotli//brotlicommon <library>/brotli//brotlidec <define>BOOST_BURL_HAS_BROTLI : ]
+     [ ac.check-library /zstd//zstd : <library>/zstd//zstd <define>BOOST_BURL_HAS_ZSTD : ]
      <library>/boost//http
      <library>/boost//json
      <library>/boost//url
@@ -51,8 +53,9 @@ lib boost_burl
      <library>/boost//capy
      <library>/boost//corosio
      [ ac.check-library /boost/corosio//boost_corosio_openssl : <library>/boost/corosio//boost_corosio_openssl : ]
-     [ ac.check-library /zlib//zlib : <library>/zlib//zlib : ]
-     [ ac.check-library /zstd//zstd : <library>/zstd//zstd : ]
+     [ ac.check-library /zlib//zlib : <library>/zlib//zlib <define>BOOST_BURL_HAS_ZLIB : ]
+     [ ac.check-library /brotli//brotlidec : <library>/brotli//brotlicommon <library>/brotli//brotlidec <define>BOOST_BURL_HAS_BROTLI : ]
+     [ ac.check-library /zstd//zstd : <library>/zstd//zstd <define>BOOST_BURL_HAS_ZSTD : ]
      <library>/boost//http
      <library>/boost//json
      <library>/boost//url

cmake/FindBrotli.cmake

@@ -0,0 +1,50 @@
+#
+# Copyright (c) 2026 Mohammad Nejati
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/cppalliance/burl
+#
+
+# Provides imported targets:
+#   Brotli::common
+#   Brotli::decoder
+#   Brotli::encoder
+
+find_path(Brotli_INCLUDE_DIR NAMES "brotli/decode.h")
+find_library(Brotli_COMMON_LIBRARY NAMES "brotlicommon")
+find_library(Brotli_DEC_LIBRARY NAMES "brotlidec")
+find_library(Brotli_ENC_LIBRARY NAMES "brotlienc")
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Brotli
+    REQUIRED_VARS
+    Brotli_INCLUDE_DIR
+    Brotli_COMMON_LIBRARY
+    Brotli_DEC_LIBRARY
+    Brotli_ENC_LIBRARY
+)
+
+if(Brotli_FOUND)
+    add_library(Brotli::common UNKNOWN IMPORTED)
+    set_target_properties(Brotli::common PROPERTIES
+        IMPORTED_LOCATION "${Brotli_COMMON_LIBRARY}"
+        INTERFACE_INCLUDE_DIRECTORIES "${Brotli_INCLUDE_DIR}")
+
+    add_library(Brotli::decoder UNKNOWN IMPORTED)
+    set_target_properties(Brotli::decoder PROPERTIES
+        IMPORTED_LOCATION "${Brotli_DEC_LIBRARY}"
+        INTERFACE_INCLUDE_DIRECTORIES "${Brotli_INCLUDE_DIR}")
+
+    add_library(Brotli::encoder UNKNOWN IMPORTED)
+    set_target_properties(Brotli::encoder PROPERTIES
+        IMPORTED_LOCATION "${Brotli_ENC_LIBRARY}"
+        INTERFACE_INCLUDE_DIRECTORIES "${Brotli_INCLUDE_DIR}")
+endif()
+
+mark_as_advanced(
+    Brotli_INCLUDE_DIR
+    Brotli_COMMON_LIBRARY
+    Brotli_DEC_LIBRARY
+    Brotli_ENC_LIBRARY)

cmake/FindZstd.cmake

@@ -0,0 +1,33 @@
+#
+# Copyright (c) 2026 Mohammad Nejati
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/cppalliance/burl
+#
+
+# Provides imported targets:
+#   Zstd::Zstd
+
+find_path(Zstd_INCLUDE_DIR NAMES "zstd.h")
+find_library(Zstd_LIBRARY NAMES zstd libzstd zstd_static)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Zstd
+    REQUIRED_VARS
+    Zstd_INCLUDE_DIR
+    Zstd_LIBRARY
+)
+
+if(Zstd_FOUND)
+    add_library(Zstd::Zstd UNKNOWN IMPORTED)
+    set_target_properties(Zstd::Zstd PROPERTIES
+        IMPORTED_LOCATION "${Zstd_LIBRARY}"
+        INTERFACE_INCLUDE_DIRECTORIES "${Zstd_INCLUDE_DIR}"
+    )
+endif()
+
+mark_as_advanced(
+    Zstd_INCLUDE_DIR
+    Zstd_LIBRARY)

example/CMakeLists.txt

@@ -10,14 +10,6 @@
 add_executable(burl_example_usage usage.cpp)
 target_link_libraries(burl_example_usage PRIVATE Boost::burl Boost::hash2)
 
-if (TARGET Boost::http_zlib)
-    target_link_libraries(burl_example_usage PRIVATE Boost::http_zlib)
-endif()
-
-if (TARGET Boost::http_brotli)
-    target_link_libraries(burl_example_usage PRIVATE Boost::http_brotli)
-endif()
-
 find_package(nlohmann_json QUIET)
 if (nlohmann_json_FOUND)
     add_executable(burl_example_nlohmann_json nlohmann_json.cpp)

example/usage.cpp

@@ -11,8 +11,6 @@
 #include <boost/burl.hpp>
 #include <boost/capy.hpp>
 #include <boost/corosio.hpp>
-#include <boost/http/brotli.hpp>
-#include <boost/http/zlib.hpp>
 #include <boost/json.hpp>
 #include <boost/hash2/sha2.hpp>
 
@@ -569,13 +567,6 @@ main(int argc, char* argv[])
     corosio::io_context ioc;
     corosio::tls_context tls_ctx;
 
-#ifdef BOOST_HTTP_HAS_BROTLI
-    http::brotli::install_decode_service(capy::get_system_context());
-#endif
-#ifdef BOOST_HTTP_HAS_ZLIB
-    http::zlib::install_inflate_service(capy::get_system_context());
-#endif
-
     capy::run_async(
         ioc.get_executor(),
         [] {},

include/boost/burl/client.hpp

@@ -140,11 +140,11 @@ class client
             When enabled, `br` is included in the
             `Accept-Encoding` header and response
             bodies are decoded transparently.
-            Effective only when the Brotli decode
-            service is installed in the system
-            context. Not applied when the request
-            carries an explicit `Accept-Encoding`
-            header.
+            Effective only when the library was built
+            with Brotli support
+            (`BOOST_BURL_HAS_BROTLI`). Not applied
+            when the request carries an explicit
+            `Accept-Encoding` header.
         */
         bool brotli = true;
 
@@ -154,9 +154,9 @@ class client
             the `Accept-Encoding` header and
             response bodies are decoded
             transparently. Effective only when the
-            zlib inflate service is installed in the
-            system context. Not applied when the
-            request carries an explicit
+            library was built with zlib support
+            (`BOOST_BURL_HAS_ZLIB`). Not applied when
+            the request carries an explicit
             `Accept-Encoding` header.
         */
         bool deflate = true;
@@ -166,14 +166,27 @@ class client
             When enabled, `gzip` is included in the
             `Accept-Encoding` header and response
             bodies are decoded transparently.
-            Effective only when the zlib inflate
-            service is installed in the system
-            context. Not applied when the request
-            carries an explicit `Accept-Encoding`
-            header.
+            Effective only when the library was built
+            with zlib support
+            (`BOOST_BURL_HAS_ZLIB`). Not applied when
+            the request carries an explicit
+            `Accept-Encoding` header.
         */
         bool gzip = true;
 
+        /** Advertise and decode the zstd content coding.
+
+            When enabled, `zstd` is included in the
+            `Accept-Encoding` header and response
+            bodies are decoded transparently.
+            Effective only when the library was built
+            with zstd support
+            (`BOOST_BURL_HAS_ZSTD`). Not applied when
+            the request carries an explicit
+            `Accept-Encoding` header.
+        */
+        bool zstd = true;
+
         /** Maximum allowed size of a response body.
 
             Reading a body which exceeds the limit

include/boost/burl/detail/parser.hpp

@@ -165,8 +165,7 @@ class parser
 
     capy::io_task<std::size_t>
     do_read_some(
-        std::span<capy::mutable_buffer const> buffers,
-        bool skip_out = false);
+        std::span<capy::mutable_buffer const> buffers);
 
     struct header_deleter
     {

include/boost/burl/error.hpp

@@ -72,6 +72,14 @@ enum class error
         request.
     */
     body_size_mismatch,
+
+    /** The response body could not be decoded.
+
+        Decoding the response body according to its
+        `Content-Encoding` failed because the compressed
+        data was corrupt or invalid.
+    */
+    decode_error,
 };
 
 /** Error conditions corresponding to sets of error codes.

src/client.cpp

@@ -20,16 +20,13 @@
 
 #include <boost/capy/buffers/make_buffer.hpp>
 #include <boost/capy/ex/execution_context.hpp>
-#include <boost/capy/ex/system_context.hpp>
 #include <boost/capy/timeout.hpp>
 #include <boost/capy/write.hpp>
 #include <boost/burl/detail/response_parser.hpp>
-#include <boost/http/brotli/decode.hpp>
 #include <boost/http/field.hpp>
 #include <boost/http/request.hpp>
 #include <boost/http/response_base.hpp>
 #include <boost/http/status.hpp>
-#include <boost/http/zlib/inflate.hpp>
 
 #include <chrono>
 #include <optional>
@@ -66,6 +63,9 @@ set_accept_encoding(
     if(cfg.gzip)
         accept("gzip");
 
+    if(cfg.zstd)
+        accept("zstd");
+
     if(!accept_encoding.empty())
         headers.set(http::field::accept_encoding, accept_encoding);
 }
@@ -96,12 +96,16 @@ client::client(
           std::make_shared<detail::connection_pool>(
               exec, std::move(tls_ctx), cfg))
 {
-    // Disable codings whose decoder service is unavailable.
-    auto const& ctx = capy::get_system_context();
-    if(!ctx.has_service<http::brotli::decode_service>())
-        config_.brotli = false;
-    if(!ctx.has_service<http::zlib::inflate_service>())
-        config_.deflate = config_.gzip = false;
+    // Disable codings whose decoder was not compiled in.
+#ifndef BOOST_BURL_HAS_BROTLI
+    config_.brotli = false;
+#endif
+#ifndef BOOST_BURL_HAS_ZLIB
+    config_.deflate = config_.gzip = false;
+#endif
+#ifndef BOOST_BURL_HAS_ZSTD
+    config_.zstd = false;
+#endif
 }
 
 void