Add zstd support (#2088)

* Add zstd support

* Add zstd to CI tests

* Use use zstd cmake target instead of ZSTD. Use cmake variable for found packages

* Add missing comment for HTTPLIB_REQUIRE_ZSTD

* Fix test.yaml rebase error

* Use zstd::libzstd target

* Add include and library paths to ZSTD args

* Run clang-format

* Add zstd to httplibConfig.cmake.in

.github/workflows/test.yaml

@@ -66,7 +66,8 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libc6-dev${{ matrix.config.arch_suffix }} libstdc++-13-dev${{ matrix.config.arch_suffix }} \
             libssl-dev${{ matrix.config.arch_suffix }} libcurl4-openssl-dev${{ matrix.config.arch_suffix }} \
-            zlib1g-dev${{ matrix.config.arch_suffix }} libbrotli-dev${{ matrix.config.arch_suffix }}
+            zlib1g-dev${{ matrix.config.arch_suffix }} libbrotli-dev${{ matrix.config.arch_suffix }} \
+            libzstd-dev${{ matrix.config.arch_suffix }}
       - name: build and run tests
         run: cd test && make EXTRA_CXXFLAGS="${{ matrix.config.arch_flags }}"
       - name: run fuzz test target
@@ -126,7 +127,7 @@ jobs:
     - name: Setup msbuild on windows
       uses: microsoft/setup-msbuild@v2
     - name: Install vcpkg dependencies
-      run: vcpkg install gtest curl zlib brotli
+      run: vcpkg install gtest curl zlib brotli zstd
     - name: Install OpenSSL
       if: ${{ matrix.config.with_ssl }}
       run: choco install openssl
@@ -139,6 +140,7 @@ jobs:
         -DHTTPLIB_COMPILE=${{ matrix.config.compiled && 'ON' || 'OFF' }}
         -DHTTPLIB_REQUIRE_ZLIB=ON
         -DHTTPLIB_REQUIRE_BROTLI=ON
+        -DHTTPLIB_REQUIRE_ZSTD=ON
         -DHTTPLIB_REQUIRE_OPENSSL=${{ matrix.config.with_ssl && 'ON' || 'OFF' }}
     - name: Build ${{ matrix.config.name }}
       run: cmake --build build --config Release -- /v:m /clp:ShowCommandLine

CMakeLists.txt

@@ -4,9 +4,11 @@
 	* HTTPLIB_USE_OPENSSL_IF_AVAILABLE (default on)
 	* HTTPLIB_USE_ZLIB_IF_AVAILABLE (default on)
 	* HTTPLIB_USE_BROTLI_IF_AVAILABLE (default on)
+	* HTTPLIB_USE_ZSTD_IF_AVAILABLE (default on)
 	* HTTPLIB_REQUIRE_OPENSSL (default off)
 	* HTTPLIB_REQUIRE_ZLIB (default off)
 	* HTTPLIB_REQUIRE_BROTLI (default off)
+	* HTTPLIB_REQUIRE_ZSTD (default off)
 	* HTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN (default on)
 	* HTTPLIB_COMPILE (default off)
 	* HTTPLIB_INSTALL (default on)
@@ -45,6 +47,7 @@
 	* HTTPLIB_IS_USING_OPENSSL - a bool for if OpenSSL support is enabled.
 	* HTTPLIB_IS_USING_ZLIB - a bool for if ZLIB support is enabled.
 	* HTTPLIB_IS_USING_BROTLI - a bool for if Brotli support is enabled.
+	* HTTPLIB_IS_USING_ZSTD - a bool for if ZSTD support is enabled.
 	* HTTPLIB_IS_USING_CERTS_FROM_MACOSX_KEYCHAIN - a bool for if support of loading system certs from the Apple Keychain is enabled.
 	* HTTPLIB_IS_COMPILED - a bool for if the library is compiled, or otherwise header-only.
 	* HTTPLIB_INCLUDE_DIR - the root path to httplib's header (e.g. /usr/include).
@@ -101,6 +104,8 @@ option(HTTPLIB_TEST "Enables testing and builds tests" OFF)
 option(HTTPLIB_REQUIRE_BROTLI "Requires Brotli to be found & linked, or fails build." OFF)
 option(HTTPLIB_USE_BROTLI_IF_AVAILABLE "Uses Brotli (if available) to enable Brotli decompression support." ON)
 option(HTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN "Enable feature to load system certs from the Apple Keychain." ON)
+option(HTTPLIB_REQUIRE_ZSTD "Requires ZSTD to be found & linked, or fails build." OFF)
+option(HTTPLIB_USE_ZSTD_IF_AVAILABLE "Uses ZSTD (if available) to enable zstd support." ON)
 # Defaults to static library
 option(BUILD_SHARED_LIBS "Build the library as a shared library instead of static. Has no effect if using header-only." OFF)
 if (BUILD_SHARED_LIBS AND WIN32 AND HTTPLIB_COMPILE)
@@ -153,6 +158,14 @@ elseif(HTTPLIB_USE_BROTLI_IF_AVAILABLE)
 	set(HTTPLIB_IS_USING_BROTLI ${Brotli_FOUND})
 endif()
 
+if(HTTPLIB_REQUIRE_ZSTD)
+	find_package(zstd REQUIRED)
+	set(HTTPLIB_IS_USING_ZSTD TRUE)
+elseif(HTTPLIB_USE_ZSTD_IF_AVAILABLE)
+	find_package(zstd QUIET)
+	set(HTTPLIB_IS_USING_ZSTD ${zstd_FOUND})
+endif()
+
 # Used for default, common dirs that the end-user can change (if needed)
 # like CMAKE_INSTALL_INCLUDEDIR or CMAKE_INSTALL_DATADIR
 include(GNUInstallDirs)
@@ -227,6 +240,7 @@ target_link_libraries(${PROJECT_NAME} ${_INTERFACE_OR_PUBLIC}
 		$<$<BOOL:${HTTPLIB_IS_USING_BROTLI}>:Brotli::encoder>
 		$<$<BOOL:${HTTPLIB_IS_USING_BROTLI}>:Brotli::decoder>
 		$<$<BOOL:${HTTPLIB_IS_USING_ZLIB}>:ZLIB::ZLIB>
+		$<$<BOOL:${HTTPLIB_IS_USING_ZSTD}>:zstd::libzstd>
 		$<$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>:OpenSSL::SSL>
 		$<$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>:OpenSSL::Crypto>
 )
@@ -236,6 +250,7 @@ target_compile_definitions(${PROJECT_NAME} ${_INTERFACE_OR_PUBLIC}
 	$<$<BOOL:${HTTPLIB_NO_EXCEPTIONS}>:CPPHTTPLIB_NO_EXCEPTIONS>
 	$<$<BOOL:${HTTPLIB_IS_USING_BROTLI}>:CPPHTTPLIB_BROTLI_SUPPORT>
 	$<$<BOOL:${HTTPLIB_IS_USING_ZLIB}>:CPPHTTPLIB_ZLIB_SUPPORT>
+	$<$<BOOL:${HTTPLIB_IS_USING_ZSTD}>:CPPHTTPLIB_ZSTD_SUPPORT>
 	$<$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>:CPPHTTPLIB_OPENSSL_SUPPORT>
 	$<$<AND:$<PLATFORM_ID:Darwin>,$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>,$<BOOL:${HTTPLIB_IS_USING_CERTS_FROM_MACOSX_KEYCHAIN}>>:CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN>
 )

cmake/httplibConfig.cmake.in

@@ -35,6 +35,10 @@ if(@HTTPLIB_IS_USING_BROTLI@)
 	find_dependency(Brotli COMPONENTS common encoder decoder)
 endif()
 
+if(@HTTPLIB_IS_USING_ZSTD@)
+	find_dependency(zstd)
+endif()
+
 # Mildly useful for end-users
 # Not really recommended to be used though
 set_and_check(HTTPLIB_INCLUDE_DIR "@PACKAGE_CMAKE_INSTALL_FULL_INCLUDEDIR@")
@@ -46,6 +50,7 @@ set_and_check(HTTPLIB_HEADER_PATH "@PACKAGE_CMAKE_INSTALL_FULL_INCLUDEDIR@/httpl
 set(httplib_OpenSSL_FOUND @HTTPLIB_IS_USING_OPENSSL@)
 set(httplib_ZLIB_FOUND @HTTPLIB_IS_USING_ZLIB@)
 set(httplib_Brotli_FOUND @HTTPLIB_IS_USING_BROTLI@)
+set(httplib_zstd_FOUND @HTTPLIB_IS_USING_ZSTD@)
 
 check_required_components(httplib)
 

httplib.h

@@ -312,6 +312,10 @@ using socket_t = int;
 #include <brotli/encode.h>
 #endif
 
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+#include <zstd.h>
+#endif
+
 /*
  * Declaration
  */
@@ -2445,7 +2449,7 @@ ssize_t send_socket(socket_t sock, const void *ptr, size_t size, int flags);
 
 ssize_t read_socket(socket_t sock, void *ptr, size_t size, int flags);
 
-enum class EncodingType { None = 0, Gzip, Brotli };
+enum class EncodingType { None = 0, Gzip, Brotli, Zstd };
 
 EncodingType encoding_type(const Request &req, const Response &res);
 
@@ -2558,6 +2562,34 @@ private:
 };
 #endif
 
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+class zstd_compressor : public compressor {
+public:
+  zstd_compressor();
+  ~zstd_compressor();
+
+  bool compress(const char *data, size_t data_length, bool last,
+                Callback callback) override;
+
+private:
+  ZSTD_CCtx *ctx_ = nullptr;
+};
+
+class zstd_decompressor : public decompressor {
+public:
+  zstd_decompressor();
+  ~zstd_decompressor();
+
+  bool is_valid() const override;
+
+  bool decompress(const char *data, size_t data_length,
+                  Callback callback) override;
+
+private:
+  ZSTD_DCtx *ctx_ = nullptr;
+};
+#endif
+
 // NOTE: until the read size reaches `fixed_buffer_size`, use `fixed_buffer`
 // to store data. The call can set memory on stack for performance.
 class stream_line_reader {
@@ -3949,6 +3981,12 @@ inline EncodingType encoding_type(const Request &req, const Response &res) {
   if (ret) { return EncodingType::Gzip; }
 #endif
 
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+  // TODO: 'Accept-Encoding' has zstd, not zstd;q=0
+  ret = s.find("zstd") != std::string::npos;
+  if (ret) { return EncodingType::Zstd; }
+#endif
+
   return EncodingType::None;
 }
 
@@ -4157,6 +4195,61 @@ inline bool brotli_decompressor::decompress(const char *data,
 }
 #endif
 
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+inline zstd_compressor::zstd_compressor() {
+  ctx_ = ZSTD_createCCtx();
+  ZSTD_CCtx_setParameter(ctx_, ZSTD_c_compressionLevel, ZSTD_fast);
+}
+
+inline zstd_compressor::~zstd_compressor() { ZSTD_freeCCtx(ctx_); }
+
+inline bool zstd_compressor::compress(const char *data, size_t data_length,
+                                      bool last, Callback callback) {
+  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
+
+  ZSTD_EndDirective mode = last ? ZSTD_e_end : ZSTD_e_continue;
+  ZSTD_inBuffer input = {data, data_length, 0};
+
+  bool finished;
+  do {
+    ZSTD_outBuffer output = {buff.data(), CPPHTTPLIB_COMPRESSION_BUFSIZ, 0};
+    size_t const remaining = ZSTD_compressStream2(ctx_, &output, &input, mode);
+
+    if (ZSTD_isError(remaining)) { return false; }
+
+    if (!callback(buff.data(), output.pos)) { return false; }
+
+    finished = last ? (remaining == 0) : (input.pos == input.size);
+
+  } while (!finished);
+
+  return true;
+}
+
+inline zstd_decompressor::zstd_decompressor() { ctx_ = ZSTD_createDCtx(); }
+
+inline zstd_decompressor::~zstd_decompressor() { ZSTD_freeDCtx(ctx_); }
+
+inline bool zstd_decompressor::is_valid() const { return ctx_ != nullptr; }
+
+inline bool zstd_decompressor::decompress(const char *data, size_t data_length,
+                                          Callback callback) {
+  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
+  ZSTD_inBuffer input = {data, data_length, 0};
+
+  while (input.pos < input.size) {
+    ZSTD_outBuffer output = {buff.data(), CPPHTTPLIB_COMPRESSION_BUFSIZ, 0};
+    size_t const remaining = ZSTD_decompressStream(ctx_, &output, &input);
+
+    if (ZSTD_isError(remaining)) { return false; }
+
+    if (!callback(buff.data(), output.pos)) { return false; }
+  }
+
+  return true;
+}
+#endif
+
 inline bool has_header(const Headers &headers, const std::string &key) {
   return headers.find(key) != headers.end();
 }
@@ -4397,6 +4490,13 @@ bool prepare_content_receiver(T &x, int &status,
 #else
       status = StatusCode::UnsupportedMediaType_415;
       return false;
+#endif
+    } else if (encoding == "zstd") {
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+      decompressor = detail::make_unique<zstd_decompressor>();
+#else
+      status = StatusCode::UnsupportedMediaType_415;
+      return false;
 #endif
     }
 
@@ -6634,6 +6734,10 @@ Server::write_content_with_provider(Stream &strm, const Request &req,
       } else if (type == detail::EncodingType::Brotli) {
 #ifdef CPPHTTPLIB_BROTLI_SUPPORT
         compressor = detail::make_unique<detail::brotli_compressor>();
+#endif
+      } else if (type == detail::EncodingType::Zstd) {
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+        compressor = detail::make_unique<detail::zstd_compressor>();
 #endif
       } else {
         compressor = detail::make_unique<detail::nocompressor>();
@@ -7049,6 +7153,8 @@ inline void Server::apply_ranges(const Request &req, Response &res,
             res.set_header("Content-Encoding", "gzip");
           } else if (type == detail::EncodingType::Brotli) {
             res.set_header("Content-Encoding", "br");
+          } else if (type == detail::EncodingType::Zstd) {
+            res.set_header("Content-Encoding", "zstd");
           }
         }
       }
@@ -7088,6 +7194,11 @@ inline void Server::apply_ranges(const Request &req, Response &res,
 #ifdef CPPHTTPLIB_BROTLI_SUPPORT
         compressor = detail::make_unique<detail::brotli_compressor>();
         content_encoding = "br";
+#endif
+      } else if (type == detail::EncodingType::Zstd) {
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+        compressor = detail::make_unique<detail::zstd_compressor>();
+        content_encoding = "zstd";
 #endif
       }
 
@@ -7812,6 +7923,10 @@ inline bool ClientImpl::write_request(Stream &strm, Request &req,
 #ifdef CPPHTTPLIB_ZLIB_SUPPORT
       if (!accept_encoding.empty()) { accept_encoding += ", "; }
       accept_encoding += "gzip, deflate";
+#endif
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+      if (!accept_encoding.empty()) { accept_encoding += ", "; }
+      accept_encoding += "zstd";
 #endif
       req.set_header("Accept-Encoding", accept_encoding);
     }
@@ -10377,4 +10492,4 @@ inline SSL_CTX *Client::ssl_context() const {
 
 } // namespace httplib
 
-#endif // CPPHTTPLIB_HTTPLIB_H
+#endif // CPPHTTPLIB_HTTPLIB_H

test/Makefile

@@ -18,7 +18,10 @@ ZLIB_SUPPORT = -DCPPHTTPLIB_ZLIB_SUPPORT -lz
 BROTLI_DIR = $(PREFIX)/opt/brotli
 BROTLI_SUPPORT = -DCPPHTTPLIB_BROTLI_SUPPORT -I$(BROTLI_DIR)/include -L$(BROTLI_DIR)/lib -lbrotlicommon -lbrotlienc -lbrotlidec
 
-TEST_ARGS = gtest/src/gtest-all.cc gtest/src/gtest_main.cc -Igtest -Igtest/include $(OPENSSL_SUPPORT) $(ZLIB_SUPPORT) $(BROTLI_SUPPORT) -pthread -lcurl
+ZSTD_DIR = $(PREFIX)/opt/zstd
+ZSTD_SUPPORT = -DCPPHTTPLIB_ZSTD_SUPPORT -I$(ZSTD_DIR)/include -L$(ZSTD_DIR)/lib -lzstd
+
+TEST_ARGS = gtest/src/gtest-all.cc gtest/src/gtest_main.cc -Igtest -Igtest/include $(OPENSSL_SUPPORT) $(ZLIB_SUPPORT) $(BROTLI_SUPPORT) $(ZSTD_SUPPORT) -pthread -lcurl
 
 # By default, use standalone_fuzz_target_runner.
 # This runner does no fuzzing, but simply executes the inputs

test/test.cc

@@ -668,7 +668,7 @@ TEST(ParseAcceptEncoding1, AcceptEncoding) {
 
 TEST(ParseAcceptEncoding2, AcceptEncoding) {
   Request req;
-  req.set_header("Accept-Encoding", "gzip, deflate, br");
+  req.set_header("Accept-Encoding", "gzip, deflate, br, zstd");
 
   Response res;
   res.set_header("Content-Type", "text/plain");
@@ -679,6 +679,8 @@ TEST(ParseAcceptEncoding2, AcceptEncoding) {
   EXPECT_TRUE(ret == detail::EncodingType::Brotli);
 #elif CPPHTTPLIB_ZLIB_SUPPORT
   EXPECT_TRUE(ret == detail::EncodingType::Gzip);
+#elif CPPHTTPLIB_ZSTD_SUPPORT
+  EXPECT_TRUE(ret == detail::EncodingType::Zstd);
 #else
   EXPECT_TRUE(ret == detail::EncodingType::None);
 #endif
@@ -686,7 +688,8 @@ TEST(ParseAcceptEncoding2, AcceptEncoding) {
 
 TEST(ParseAcceptEncoding3, AcceptEncoding) {
   Request req;
-  req.set_header("Accept-Encoding", "br;q=1.0, gzip;q=0.8, *;q=0.1");
+  req.set_header("Accept-Encoding",
+                 "br;q=1.0, gzip;q=0.8, zstd;q=0.8, *;q=0.1");
 
   Response res;
   res.set_header("Content-Type", "text/plain");
@@ -697,6 +700,8 @@ TEST(ParseAcceptEncoding3, AcceptEncoding) {
   EXPECT_TRUE(ret == detail::EncodingType::Brotli);
 #elif CPPHTTPLIB_ZLIB_SUPPORT
   EXPECT_TRUE(ret == detail::EncodingType::Gzip);
+#elif CPPHTTPLIB_ZSTD_SUPPORT
+  EXPECT_TRUE(ret == detail::EncodingType::Zstd);
 #else
   EXPECT_TRUE(ret == detail::EncodingType::None);
 #endif
@@ -3007,7 +3012,8 @@ protected:
                    const httplib::ContentReader &) {
                   res.set_content("ok", "text/plain");
                 })
-#if defined(CPPHTTPLIB_ZLIB_SUPPORT) || defined(CPPHTTPLIB_BROTLI_SUPPORT)
+#if defined(CPPHTTPLIB_ZLIB_SUPPORT) || defined(CPPHTTPLIB_BROTLI_SUPPORT) ||  \
+    defined(CPPHTTPLIB_ZSTD_SUPPORT)
         .Get("/compress",
              [&](const Request & /*req*/, Response &res) {
                res.set_content(
@@ -4928,6 +4934,245 @@ TEST_F(ServerTest, Brotli) {
 }
 #endif
 
+#ifdef CPPHTTPLIB_ZSTD_SUPPORT
+TEST_F(ServerTest, Zstd) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+  auto res = cli_.Get("/compress", headers);
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ("zstd", res->get_header_value("Content-Encoding"));
+  EXPECT_EQ("text/plain", res->get_header_value("Content-Type"));
+  EXPECT_EQ("26", res->get_header_value("Content-Length"));
+  EXPECT_EQ("123456789012345678901234567890123456789012345678901234567890123456"
+            "7890123456789012345678901234567890",
+            res->body);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+TEST_F(ServerTest, ZstdWithoutAcceptEncoding) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "");
+  auto res = cli_.Get("/compress", headers);
+
+  ASSERT_TRUE(res);
+  EXPECT_TRUE(res->get_header_value("Content-Encoding").empty());
+  EXPECT_EQ("text/plain", res->get_header_value("Content-Type"));
+  EXPECT_EQ("100", res->get_header_value("Content-Length"));
+  EXPECT_EQ("123456789012345678901234567890123456789012345678901234567890123456"
+            "7890123456789012345678901234567890",
+            res->body);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+TEST_F(ServerTest, ZstdWithContentReceiver) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+  std::string body;
+  auto res = cli_.Get("/compress", headers,
+                      [&](const char *data, uint64_t data_length) {
+                        EXPECT_EQ(100U, data_length);
+                        body.append(data, data_length);
+                        return true;
+                      });
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ("zstd", res->get_header_value("Content-Encoding"));
+  EXPECT_EQ("text/plain", res->get_header_value("Content-Type"));
+  EXPECT_EQ("26", res->get_header_value("Content-Length"));
+  EXPECT_EQ("123456789012345678901234567890123456789012345678901234567890123456"
+            "7890123456789012345678901234567890",
+            body);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+TEST_F(ServerTest, ZstdWithoutDecompressing) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+
+  cli_.set_decompress(false);
+  auto res = cli_.Get("/compress", headers);
+
+  unsigned char compressed[26] = {0x28, 0xb5, 0x2f, 0xfd, 0x20, 0x64, 0x8d,
+                                  0x00, 0x00, 0x50, 0x31, 0x32, 0x33, 0x34,
+                                  0x35, 0x36, 0x37, 0x38, 0x39, 0x30, 0x01,
+                                  0x00, 0xd7, 0xa9, 0x20, 0x01};
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ("zstd", res->get_header_value("Content-Encoding"));
+  EXPECT_EQ("text/plain", res->get_header_value("Content-Type"));
+  EXPECT_EQ("26", res->get_header_value("Content-Length"));
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+  ASSERT_EQ(26U, res->body.size());
+  EXPECT_TRUE(std::memcmp(compressed, res->body.data(), sizeof(compressed)) ==
+              0);
+}
+
+TEST_F(ServerTest, ZstdWithContentReceiverWithoutAcceptEncoding) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "");
+
+  std::string body;
+  auto res = cli_.Get("/compress", headers,
+                      [&](const char *data, uint64_t data_length) {
+                        EXPECT_EQ(100U, data_length);
+                        body.append(data, data_length);
+                        return true;
+                      });
+
+  ASSERT_TRUE(res);
+  EXPECT_TRUE(res->get_header_value("Content-Encoding").empty());
+  EXPECT_EQ("text/plain", res->get_header_value("Content-Type"));
+  EXPECT_EQ("100", res->get_header_value("Content-Length"));
+  EXPECT_EQ("123456789012345678901234567890123456789012345678901234567890123456"
+            "7890123456789012345678901234567890",
+            body);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+TEST_F(ServerTest, NoZstd) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+  auto res = cli_.Get("/nocompress", headers);
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ(false, res->has_header("Content-Encoding"));
+  EXPECT_EQ("application/octet-stream", res->get_header_value("Content-Type"));
+  EXPECT_EQ("100", res->get_header_value("Content-Length"));
+  EXPECT_EQ("123456789012345678901234567890123456789012345678901234567890123456"
+            "7890123456789012345678901234567890",
+            res->body);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+TEST_F(ServerTest, NoZstdWithContentReceiver) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+  std::string body;
+  auto res = cli_.Get("/nocompress", headers,
+                      [&](const char *data, uint64_t data_length) {
+                        EXPECT_EQ(100U, data_length);
+                        body.append(data, data_length);
+                        return true;
+                      });
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ(false, res->has_header("Content-Encoding"));
+  EXPECT_EQ("application/octet-stream", res->get_header_value("Content-Type"));
+  EXPECT_EQ("100", res->get_header_value("Content-Length"));
+  EXPECT_EQ("123456789012345678901234567890123456789012345678901234567890123456"
+            "7890123456789012345678901234567890",
+            body);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+// TODO: How to enable zstd ??
+TEST_F(ServerTest, MultipartFormDataZstd) {
+  MultipartFormDataItems items = {
+      {"key1", "test", "", ""},
+      {"key2", "--abcdefg123", "", ""},
+  };
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+
+  cli_.set_compress(true);
+  auto res = cli_.Post("/compress-multipart", headers, items);
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+}
+
+TEST_F(ServerTest, PutWithContentProviderWithZstd) {
+  Headers headers;
+  headers.emplace("Accept-Encoding", "zstd");
+
+  cli_.set_compress(true);
+  auto res = cli_.Put(
+      "/put", headers, 3,
+      [](size_t /*offset*/, size_t /*length*/, DataSink &sink) {
+        sink.os << "PUT";
+        return true;
+      },
+      "text/plain");
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ(StatusCode::OK_200, res->status);
+  EXPECT_EQ("PUT", res->body);
+}
+
+TEST(ZstdDecompressor, ChunkedDecompression) {
+  std::string data;
+  for (size_t i = 0; i < 32 * 1024; ++i) {
+    data.push_back(static_cast<char>('a' + i % 26));
+  }
+
+  std::string compressed_data;
+  {
+    httplib::detail::zstd_compressor compressor;
+    bool result = compressor.compress(
+        data.data(), data.size(),
+        /*last=*/true,
+        [&](const char *compressed_data_chunk, size_t compressed_data_size) {
+          compressed_data.insert(compressed_data.size(), compressed_data_chunk,
+                                 compressed_data_size);
+          return true;
+        });
+    ASSERT_TRUE(result);
+  }
+
+  std::string decompressed_data;
+  {
+    httplib::detail::zstd_decompressor decompressor;
+
+    // Chunk size is chosen specifically to have a decompressed chunk size equal
+    // to 16384 bytes 16384 bytes is the size of decompressor output buffer
+    size_t chunk_size = 130;
+    for (size_t chunk_begin = 0; chunk_begin < compressed_data.size();
+         chunk_begin += chunk_size) {
+      size_t current_chunk_size =
+          std::min(compressed_data.size() - chunk_begin, chunk_size);
+      bool result = decompressor.decompress(
+          compressed_data.data() + chunk_begin, current_chunk_size,
+          [&](const char *decompressed_data_chunk,
+              size_t decompressed_data_chunk_size) {
+            decompressed_data.insert(decompressed_data.size(),
+                                     decompressed_data_chunk,
+                                     decompressed_data_chunk_size);
+            return true;
+          });
+      ASSERT_TRUE(result);
+    }
+  }
+  ASSERT_EQ(data, decompressed_data);
+}
+
+TEST(ZstdDecompressor, Decompress) {
+  std::string original_text = "Compressed with ZSTD";
+  unsigned char data[29] = {0x28, 0xb5, 0x2f, 0xfd, 0x20, 0x14, 0xa1, 0x00,
+                            0x00, 0x43, 0x6f, 0x6d, 0x70, 0x72, 0x65, 0x73,
+                            0x73, 0x65, 0x64, 0x20, 0x77, 0x69, 0x74, 0x68,
+                            0x20, 0x5a, 0x53, 0x54, 0x44};
+  std::string compressed_data(data, data + sizeof(data) / sizeof(data[0]));
+
+  std::string decompressed_data;
+  {
+    httplib::detail::zstd_decompressor decompressor;
+
+    bool result = decompressor.decompress(
+        compressed_data.data(), compressed_data.size(),
+        [&](const char *decompressed_data_chunk,
+            size_t decompressed_data_chunk_size) {
+          decompressed_data.insert(decompressed_data.size(),
+                                   decompressed_data_chunk,
+                                   decompressed_data_chunk_size);
+          return true;
+        });
+    ASSERT_TRUE(result);
+  }
+  ASSERT_EQ(original_text, decompressed_data);
+}
+#endif
+
 // Sends a raw request to a server listening at HOST:PORT.
 static bool send_request(time_t read_timeout_sec, const std::string &req,
                          std::string *resp = nullptr) {