Add zstd support

Author: davidalo

CMakeLists.txt

@@ -4,6 +4,7 @@
 	* 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)
@@ -45,6 +46,7 @@
 	* 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 +103,8 @@ 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 +157,17 @@ 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)
+	# FindZLIB doesn't have a ZLIB_FOUND variable, so check the target.
+	if(TARGET ZSTD::ZSTD)
+		set(HTTPLIB_IS_USING_ZSTD TRUE)
+	endif()
+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 +242,7 @@ 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::ZSTD>
 		$<$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>:OpenSSL::SSL>
 		$<$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>:OpenSSL::Crypto>
 )
@@ -236,6 +252,7 @@ target_compile_definitions(${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>
 )

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 @@ class brotli_decompressor final : public decompressor {
 };
 #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 +4195,75 @@ 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 +4504,13 @@ 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 +6748,10 @@ 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 +7167,8 @@ 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 +7208,11 @@ 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 +7937,10 @@ 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);
     }