refactor(packet): replace zlib with zstd compression and restructure header

Increase header length to 12 bytes, add CompressType and PacketHeader struct, and implement decode_packet_header. Update CMake to find zstd and link against it, adding Findzstd module.

CMakeLists.txt

@@ -17,11 +17,11 @@ set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 if(MSVC)
     add_compile_options(/utf-8)
 endif()
-
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules")
 find_package(OpenGL REQUIRED)
 find_package(Protobuf REQUIRED)
 find_package(absl REQUIRED)
-find_package(ZLIB REQUIRED)
+find_package(zstd REQUIRED)
 
 if (UNIX AND NOT APPLE)
     find_package(Freetype REQUIRED)
@@ -208,7 +208,7 @@ target_link_libraries(${PROJECT_NAME}
         protobuf::libprotobuf
         absl::log
         absl::check
-        ZLIB::ZLIB
+        zstd::zstd
 )
 
 if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")

cmake/modules/Findzstd.cmake

@@ -0,0 +1,22 @@
+find_path(ZSTD_INCLUDE_DIRS
+  NAMES zstd.h
+  HINTS ${zstd_ROOT_DIR}/include)
+
+find_library(ZSTD_LIBRARIES
+  NAMES zstd
+  HINTS ${zstd_ROOT_DIR}/lib)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(zstd DEFAULT_MSG ZSTD_LIBRARIES ZSTD_INCLUDE_DIRS)
+
+mark_as_advanced(
+  ZSTD_LIBRARIES
+  ZSTD_INCLUDE_DIRS)
+
+if(ZSTD_FOUND AND NOT (TARGET zstd::zstd))
+  add_library (zstd::zstd UNKNOWN IMPORTED)
+  set_target_properties(zstd::zstd
+    PROPERTIES
+      IMPORTED_LOCATION ${ZSTD_LIBRARIES}
+      INTERFACE_INCLUDE_DIRECTORIES ${ZSTD_INCLUDE_DIRS})
+endif()

include/Cubed/gameplay/packet.hpp

@@ -1,12 +1,41 @@
 #pragma once
 #include "packet.pb.h" // IWYU pragma: keep
 
+#include <array>
+#include <cstdint>
+#include <cstring>
+#include <memory>
 #include <netinet/in.h>
+#include <stdexcept>
 #include <type_traits>
 #include <utility>
+
 namespace Cubed {
-constexpr int HEADER_LEN = 8;
+constexpr int HEADER_LEN = 12;
 using Packet = std::shared_ptr<std::vector<uint8_t>>;
+enum class CompressType : uint16_t {
+    NONE = 0,
+    ZSTD = 1,
+};
+
+inline CompressType get_compress_type(uint16_t id) {
+    using enum CompressType;
+    constexpr auto& to = std::to_underlying<CompressType>;
+    switch (id) {
+    case to(NONE):
+        return NONE;
+    case to(ZSTD):
+        return ZSTD;
+    }
+    throw std::runtime_error(std::format("Unkown CompressType {}", id));
+}
+
+struct PacketHeader {
+    uint16_t cmd;
+    CompressType compress_type; // 0=none 1=zlib
+    uint32_t uncompressed_size;
+    uint32_t compressed_size;
+};
 
 enum class PacketEnum {
     LOGIN_REQ = 1001,
@@ -59,7 +88,7 @@ template <typename T> constexpr uint16_t get_packet_id() {
         return to_num(UPDATE_TIME);
     } else if constexpr (is_same_v<U, Ping>) {
         return to_num(PING);
-    } else if (is_same_v<U, Pong>) {
+    } else if constexpr (is_same_v<U, Pong>) {
         return to_num(PONG);
     } else {
         static_assert(always_false<U>::value, "Unkonw Type");
@@ -67,27 +96,54 @@ template <typename T> constexpr uint16_t get_packet_id() {
 }
 
 template <typename T> Packet make_packet(const T& msg) {
-    uint16_t cmd = get_packet_id<T>();
+    PacketHeader header{};
+    header.cmd = get_packet_id<T>();
+    uint32_t size = static_cast<uint32_t>(msg.ByteSizeLong());
+    header.uncompressed_size = size;
+    header.compressed_size = size;
+    header.compress_type = CompressType::NONE;
 
-    uint32_t body_len = static_cast<uint32_t>(msg.ByteSizeLong());
+    auto packet = std::make_shared<std::vector<uint8_t>>(
+        HEADER_LEN + header.compressed_size);
 
-    uint32_t total_len = HEADER_LEN + body_len;
+    uint16_t cmd_net = htons(header.cmd);
+    uint16_t compress_type_net =
+        htons(std::to_underlying(header.compress_type));
+    uint32_t uncompressed_size_net = htonl(header.uncompressed_size);
+    uint32_t compressed_size_net = htonl(header.compressed_size);
 
-    auto packet = std::make_shared<std::vector<uint8_t>>(total_len);
-
-    uint32_t total_len_net = htonl(total_len);
-    uint16_t cmd_net = htons(cmd);
-
-    std::memcpy(packet->data(), &total_len_net, sizeof(total_len_net));
-
-    std::memcpy(packet->data() + 4, &cmd_net, sizeof(cmd_net));
+    std::memcpy(packet->data(), &cmd_net, sizeof(cmd_net));
 
+    std::memcpy(packet->data() + 2, &compress_type_net,
+                sizeof(compress_type_net));
+    std::memcpy(packet->data() + 4, &uncompressed_size_net,
+                sizeof(uncompressed_size_net));
+    std::memcpy(packet->data() + 8, &compressed_size_net,
+                sizeof(compressed_size_net));
     if (!msg.SerializeToArray(packet->data() + HEADER_LEN,
-                              static_cast<int>(body_len))) {
+                              static_cast<int>(size))) {
         return {};
     }
 
     return packet;
 }
 
+inline PacketHeader
+decode_packet_header(const std::array<char, HEADER_LEN>& header) {
+    uint16_t cmd_net;
+    uint16_t compress_type_net;
+    uint32_t uncompressed_size_net;
+    uint32_t compressed_size_net;
+    std::memcpy(&cmd_net, header.data(), sizeof(cmd_net));
+    std::memcpy(&compress_type_net, header.data() + 2,
+                sizeof(compress_type_net));
+    std::memcpy(&uncompressed_size_net, header.data() + 4,
+                sizeof(uncompressed_size_net));
+    std::memcpy(&compressed_size_net, header.data() + 8,
+                sizeof(compressed_size_net));
+
+    return {ntohs(cmd_net), get_compress_type(ntohs(compress_type_net)),
+            ntohl(uncompressed_size_net), ntohl(compressed_size_net)};
+}
+
 } // namespace Cubed

src/dev_panel.cpp

@@ -113,7 +113,7 @@ void DevPanel::show_about_table_bar() {
         ImGui::Text("Tbb");
         ImGui::Text("Asio");
         ImGui::Text("protobuf");
-        ImGui::Text("zlib");
+        ImGui::Text("zstd");
         ImGui::Separator();
         ImGui::Text("Special Thanks");
         ImGui::Text("TANGERIME");