libac: First Commit

27 files changed, 2533 insertions, 1 deletions

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..e5605ba
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "client/libacron/wic"]
+	path = client/libacron/wic
+	url = https://github.com/cjhdev/wic.git
diff --git a/README.md b/README.md
index 14ccff9..aa7f24f 100644
--- a/README.md
+++ b/README.md
@@ -569,4 +569,4 @@ the email subject. If you are sending a patch, please include `[PATCH]` in the s
 
 ## License
 
-GPL v2 only.
+Acron is licensed under GPL-2.0-only except libac is licensed under LGPL-2.1-only.
diff --git a/client/libacron/.gitignore b/client/libacron/.gitignore
new file mode 100644
index 0000000..1bab38a
--- /dev/null
+++ b/client/libacron/.gitignore
@@ -0,0 +1,81 @@
+cmake-build-debug/
+cmake-build-release/
+
+# https://raw.githubusercontent.com/github/gitignore/main/Global/JetBrains.gitignore
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# AWS User-specific
+.idea/**/aws.xml
+
+# Generated files
+.idea/**/contentModel.xml
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Gradle and Maven with auto-import
+# When using Gradle or Maven with auto-import, you should exclude module files,
+# since they will be recreated, and may cause churn.  Uncomment if using
+# auto-import.
+# .idea/artifacts
+# .idea/compiler.xml
+# .idea/jarRepositories.xml
+# .idea/modules.xml
+# .idea/*.iml
+# .idea/modules
+# *.iml
+# *.ipr
+
+# CMake
+cmake-build-*/
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# SonarLint plugin
+.idea/sonarlint/
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# Android studio 3.1+ serialized cache file
+.idea/caches/build_file_checksums.ser
diff --git a/client/libacron/CMakeLists.txt b/client/libacron/CMakeLists.txt
new file mode 100644
index 0000000..71c0529
--- /dev/null
+++ b/client/libacron/CMakeLists.txt
@@ -0,0 +1,47 @@
+cmake_minimum_required(VERSION 3.22)
+project(libac C)
+
+set(CMAKE_C_STANDARD 11)
+
+set(CMAKE_C_FLAGS_DEBUG
+        "${CMAKE_C_FLAGS_DEBUG} -g3 -O0 -fsanitize=address -DDEBUG")
+set(CMAKE_EXE_LINKER_FLAGS_DEBUG
+        "${CMAKE_EXE_LINKER_FLAGS_DEBUG} -fsanitize=address")
+add_definitions(-D_POSIX_C_SOURCE=200809L)
+
+set(CMAKE_SHARED_LINKER_FLAGS ${CMAKE_SHARED_LINKER_FLAGS} "-Wl,--version-script='${CMAKE_SOURCE_DIR}/export.map'")
+
+find_package(PkgConfig)
+pkg_check_modules(json-c REQUIRED json-c)
+add_library(ac SHARED
+        include/libac.h
+        include/events.h
+        include/requests.h
+        include/common.h
+        include/net.h
+        include/ids.h
+        private/config.h
+        private/serializer.c
+        private/helpers.h
+        private/helpers.c
+        private/serializer.h
+        private/log.c
+        private/log.h
+        private/connection.h
+        wic/include/http_parser.h
+        wic/include/wic.h
+        wic/src/http_parser.c
+        wic/src/wic.c
+        net.c
+        ids.c
+        requests.c
+        library.c
+        )
+target_include_directories(ac PUBLIC "${PROJECT_BINARY_DIR}" include/ private/ wic/include/)
+target_link_libraries(ac json-c)
+
+add_executable(acronc
+        acronc/main.c
+        )
+target_link_libraries(acronc ac)
+target_include_directories(acronc PUBLIC "${PROJECT_BINARY_DIR}" include/)
diff --git a/client/libacron/LICENSE b/client/libacron/LICENSE
new file mode 100644
index 0000000..8000a6f
--- /dev/null
+++ b/client/libacron/LICENSE
@@ -0,0 +1,504 @@
+                  GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the Lesser GPL.  It also counts
+ as the successor of the GNU Library Public License, version 2, hence
+ the version number 2.1.]
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+           How to Apply These Terms to Your New Libraries
+
+  If you develop a new library, and you want it to be of the greatest
+possible use to the public, we recommend making it free software that
+everyone can redistribute and change.  You can do so by permitting
+redistribution under these terms (or, alternatively, under the terms of the
+ordinary General Public License).
+
+  To apply these terms, attach the following notices to the library.  It is
+safest to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least the
+"copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the library's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+    USA
+
+Also add information on how to contact you by electronic and paper mail.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the library, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the
+  library `Frob' (a library for tweaking knobs) written by James Random
+  Hacker.
+
+  <signature of Ty Coon>, 1 April 1990
+  Ty Coon, President of Vice
+
+That's all there is to it!
diff --git a/client/libacron/README.md b/client/libacron/README.md
new file mode 100644
index 0000000..11d7663
--- /dev/null
+++ b/client/libacron/README.md
@@ -0,0 +1,199 @@
+# `libac`: Acron Client Library
+
+A client library written in C, 
+based on [json-c](https://github.com/json-c/json-c) and [wic](https://github.com/cjhdev/wic).
+
+## Building
+
+Requirements:
+
+* `json-c` installed and using PkgConfig
+* Git
+* CMake
+* A C11 or higher C compiler
+* Connectivity to this git repository and `github.com`
+
+To build on Unix:
+
+```shell
+git clone https://git.yuuta.moe/Minecraft/acron.git
+cd acron
+git submodule update --init
+cd client/libacron/
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release ..
+make
+```
+
+The shared library will be at `libac.so`.
+
+The distributable headers are at `client/libacron/include/`.
+
+To make debug builds, use the Debug build type. Debug builds will have ASAN enabled.
+
+## Usage
+
+All functions begin with `ac_`. Include `libac.h`.
+
+
+### Thread Safety
+
+This library is single-threaded, meaning that all functions should be called on a 
+dedicated thread. However, user may initialize the library on multiple threads and call
+the functions on different threads without interfering each other.
+
+### Error Handling
+
+All error codes are at `common.h`. `AC_E_*` are library errors (generated by library routines);
+`AC_ER_*` are remote errors (generated by the server), and you should match them with `ac_response_error.code`.
+
+All libac functions return an integer value of the error code. `AC_E_OK(0)` indicates successful operation.
+
+Any library function calls not following the document will return `AC_E_INVALID_REQUEST`.
+
+### Struct Inheritance
+
+All libac exported structs have a `uint8_t type` as its first member. It indicates the type of the object.
+The type ID is globally unique and stable across upgrades.
+
+Internally, the type is an unsigned 8-bit integer, with the first two bits indicating whether it is
+an event, a response, or a request. The remaining 6 bits differentiates the type with others.
+
+Library users usually do not need to care about the internal assignment of type IDs. Every exported struct
+have its ID defined in the corresponding headers (e.g. `AC_RESPONSE_OK`). Macros like `AC_IS_EVENT` is also 
+available (from `ids.h`).
+
+Thus, the base definition of all libac structs is:
+
+```c
+/* ids.h */
+typedef struct ac_obj {
+    uint8_t type;
+} ac_obj_t;
+```
+
+are classified in three types:
+
+* Event: Server-initiated events. Do not have IDs. Base definition: `ac_event_t`.
+```c
+/* events.h */
+typedef struct ac_event {
+    uint8_t type;
+} ac_event_t;
+```
+* Request: Program-allocated requests. Have a program-assigned ID. Base definition: `ac_request_t`.
+```c
+/* requests.h */
+typedef struct ac_request {
+    uint8_t type;
+    int id;
+} ac_request_t;
+```
+* Response: Responses to requests. Have the same ID as the request. Base definition: `ac_response_t`.
+```c
+/* requests.h */
+typedef struct ac_response {
+    uint8_t type;
+    int id;
+} ac_response_t;
+```
+
+### Struct Memory Management
+
+For requests only, it is the program's responsibility to allocate them (on whether stack or heap) and 
+assign the correct type, so libac can recognize them. The program should also free the request after making
+`ac_request()` calls, as libac will not modify the request object:
+
+```c
+int list(void *connection) {
+    /* Allocated on the stack: Freed upon return, not by libac. */
+    ac_request_cmd cmd = {
+            .type = AC_REQUEST_CMD,
+            .id = 114514,
+            .config = NULL,
+            .cmd = "list"
+    };
+    int r = ac_request(connection, (ac_request_t *) &cmd);
+    /* cmd is freed. */
+    return r;
+}
+```
+
+For events and responses, libac will allocate them internally, and the program should free them using 
+`ac_obj_free(ac_obj_t)` function.
+
+### Initialization
+
+To initialize the library on the current thread, call: `ac_init()`:
+
+```c
+int main(void) {
+    libac_config_t config = {
+            .out = NULL, /* Error output stream. NULL to disable any error logging. */
+            .tok = NULL
+    }
+    int r = ac_init(&config);
+    if (r) return r;
+}
+```
+
+When finished using libac on the thread, call `ac_free()`.
+
+Any function call without `ac_init()` first will return `AC_E_NOT_INITIALIZED`.
+
+### Making Connections
+
+To connect to a server on the current thread, use `ac_connect()`.
+It will output a `void *` opaque pointer referencing to the connection. Programs should
+pass this pointer as-is when making connections or disconnecting.
+
+Every thread can have multiple connections simultaneously.
+
+```c
+void *connection = NULL;
+int r;
+ac_connection_parameters_t args = {
+        .url = "ws://localhost:25575/ws?id=1&token=123"
+};
+if ((r = ac_connect(args, &connection))) {
+    return r;
+}
+/* Listen or make requests. */
+```
+
+Then, the program can listen for responses or events:
+
+```c
+ac_obj_t *obj = NULL;
+while (!interrupted || !(r = ac_receive(connection, &obj))) {
+    /* The obj is now referencing to a library allocated event or response. */
+    /* Do things with the event or response. */
+    ac_obj_free(obj);
+}
+```
+
+The program can make requests using `ac_request()`. ~~This function can 
+be called from any thread (not specific to the listening one), but any thread 
+calling this function must also call `ac_init()` first.~~ **On the roadmap.**
+
+Finally, when done, call `ac_disconnect()`. It will close the socket and free the
+`connection` parameter. The `connection` pointer after the method call is undefined.
+
+> **Notes**:
+> 
+> Only `ws://` is supported at this time. `wss://` support is
+> on the roadmap.
+
+
+Read more: `acronc/main.c` example client.
+
+## Roadmap
+
+* Make unit tests
+* SSL support
+* Calling `ac_request()` from any thread
+
+## License
+
+The libac library is licensed under LGPL-2.1-only. Other parts of Acron is still licensed under GPL-2.0-only.
diff --git a/client/libacron/acronc/main.c b/client/libacron/acronc/main.c
new file mode 100644
index 0000000..282f6e3
--- /dev/null
+++ b/client/libacron/acronc/main.c
@@ -0,0 +1,169 @@
+/*
+ * Created by yuuta on 7/20/22.
+ */
+
+#include "libac.h"
+
+#include <stdio.h>
+#include <unistd.h>
+
+static const char *world_name(const enum ac_world world) {
+    switch (world) {
+        case overworld:
+            return "overworld";
+        case nether:
+            return "nether";
+        case end:
+            return "end";
+        default:
+            return "unknown world";
+    }
+}
+
+static void handle_event(const ac_event_t *event) {
+    switch (event->type) {
+        case AC_EVENT_LAGGING: {
+            ac_event_lagging_t *o = (ac_event_lagging_t *) event;
+            printf("Server lagging: running %lu milliseconds (%lu ticks) behind.\n",
+                   o->ms,
+                   o->ticks);
+            break;
+        }
+        case AC_EVENT_ENTITY_DEATH: {
+            ac_event_entity_death_t *o = (ac_event_entity_death_t *) event;
+            printf("Entity '%s' died at %s(%.2f, %.2f, %.2f): %s.\n",
+                   o->entity.name,
+                   world_name(o->entity.world),
+                   o->entity.pos.x,
+                   o->entity.pos.y,
+                   o->entity.pos.z,
+                   o->message);
+            break;
+        }
+        case AC_EVENT_PLAYER_MESSAGE: {
+            ac_event_player_message_t *o = (ac_event_player_message_t *) event;
+            printf("Player '%s' said at %s(%.2f, %.2f, %.2f): %s.\n",
+                   o->player.name,
+                   world_name(o->player.world),
+                   o->player.pos.x,
+                   o->player.pos.y,
+                   o->player.pos.z,
+                   o->text);
+            break;
+        }
+        case AC_EVENT_PLAYER_DISCONNECT: {
+            ac_event_player_disconnect_t *o = (ac_event_player_disconnect_t *) event;
+            printf("Player '%s' disconnected at %s(%.2f, %.2f, %.2f): %s.\n",
+                   o->player.name,
+                   world_name(o->player.world),
+                   o->player.pos.x,
+                   o->player.pos.y,
+                   o->player.pos.z,
+                   o->reason);
+            break;
+        }
+        case AC_EVENT_PLAYER_JOIN: {
+            ac_event_player_join_t *o = (ac_event_player_join_t *) event;
+            printf("Player '%s' joined at %s(%.2f, %.2f, %.2f).\n",
+                   o->player.name,
+                   world_name(o->player.world),
+                   o->player.pos.x,
+                   o->player.pos.y,
+                   o->player.pos.z);
+            break;
+        }
+        default: {
+            printf("Received an unrecognized event of type '%u'.\n",
+                   event->type);
+        }
+    }
+}
+
+static void handle_response(const ac_response_t *response) {
+    switch (response->type) {
+        case AC_RESPONSE_OK: {
+            ac_response_ok_t *o = (ac_response_ok_t *) response;
+            printf("Request %d OK.\n",
+                   o->id);
+            break;
+        }
+        case AC_RESPONSE_ERROR: {
+            ac_response_error_t *o = (ac_response_error_t *) response;
+            printf("Request %d failed: %s (%d).\n",
+                   o->id,
+                   o->message,
+                   o->code);
+            break;
+        }
+        case AC_RESPONSE_CMD_OUT: {
+            ac_response_cmd_out_t *o = (ac_response_cmd_out_t *) response;
+            printf("Request %d output by %s: %s.\n",
+                   o->id,
+                   o->sender,
+                   o->out);
+            break;
+        }
+        case AC_RESPONSE_CMD_RESULT: {
+            ac_response_cmd_result_t *o = (ac_response_cmd_result_t *) response;
+            printf("Request %d is done: %s (%d).\n",
+                   o->id,
+                   o->success ? "Success" : "Failed",
+                   o->result);
+            break;
+        }
+        default: {
+            printf("Received an unrecognized response of type '%u'.\n",
+                   response->type);
+        }
+    }
+}
+
+int main(int argc, char **argv) {
+    int r;
+    libac_config_t config = {
+#ifdef DEBUG
+            .out = stderr,
+#else
+            .out = NULL,
+#endif
+            .tok = NULL
+    };
+    if ((r = ac_init(&config))) return r;
+    void *connection;
+    ac_connection_parameters_t parameters = {
+            .url = "ws://localhost:25575/ws?id=1&token=123"
+    };
+    if ((r = ac_connect(parameters, &connection))) {
+        ac_free();
+        return r;
+    }
+    ac_obj_t *obj;
+    ac_config_t conf = {
+            .name = "acronc"
+    };
+    ac_request_cmd_t req = {
+            .type = AC_REQUEST_CMD,
+            .id = 100,
+            .config = &conf,
+            .cmd = "say Hi"
+    };
+    if ((r = ac_request(connection, (ac_request_t *) &req))) {
+        ac_disconnect(connection);
+        ac_free();
+        return r;
+    }
+    while (!(r = ac_receive(connection, &obj))) {
+        if (!obj) {
+            continue;
+        }
+        if (AC_IS_EVENT(obj->type)) {
+            handle_event((ac_event_t *) obj);
+        } else if (AC_IS_RESPONSE(obj->type)) {
+            handle_response((ac_response_t *) obj);
+        }
+        ac_object_free(obj);
+    }
+    ac_disconnect(connection);
+    ac_free();
+    return r;
+}
\ No newline at end of file
diff --git a/client/libacron/export.map b/client/libacron/export.map
new file mode 100644
index 0000000..1d805fa
--- /dev/null
+++ b/client/libacron/export.map
@@ -0,0 +1,4 @@
+AC {
+  global: ac_*;
+  local: *;
+};
\ No newline at end of file
diff --git a/client/libacron/ids.c b/client/libacron/ids.c
new file mode 100644
index 0000000..89fff9a
--- /dev/null
+++ b/client/libacron/ids.c
@@ -0,0 +1,80 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#include "log.h"
+#include "common.h"
+#include "libac.h"
+
+#include <stdlib.h>
+
+int ac_object_free(ac_obj_t *obj) {
+    switch (obj->type & 192 /* 0b11000000 */) {
+        case AC_TYPE_EVENT: {
+            switch (obj->type) {
+                case AC_EVENT_PLAYER_JOIN: {
+                    ac_event_player_join_t *v = (ac_event_player_join_t *) obj;
+                    if (v->player.name) free(v->player.name);
+                    if (v->player.uuid) free(v->player.uuid);
+                    goto ok;
+                }
+                case AC_EVENT_PLAYER_DISCONNECT: {
+                    ac_event_player_disconnect_t *v = (ac_event_player_disconnect_t *) obj;
+                    if (v->player.name) free(v->player.name);
+                    if (v->player.uuid) free(v->player.uuid);
+                    if (v->reason) free(v->reason);
+                    goto ok;
+                }
+                case AC_EVENT_ENTITY_DEATH: {
+                    ac_event_entity_death_t *v = (ac_event_entity_death_t *) obj;
+                    if (v->entity.name) free(v->entity.name);
+                    if (v->entity.uuid) free(v->entity.uuid);
+                    if (v->message) free(v->message);
+                    goto ok;
+                }
+                case AC_EVENT_PLAYER_MESSAGE: {
+                    ac_event_player_message_t *v = (ac_event_player_message_t *) obj;
+                    if (v->player.name) free(v->player.name);
+                    if (v->player.uuid) free(v->player.uuid);
+                    if (v->text) free(v->text);
+                    goto ok;
+                }
+                case AC_EVENT_LAGGING: {
+                    goto ok;
+                }
+            }
+        }
+        case AC_TYPE_REQUEST:
+            /* Request objects are user-allocated. Do not free them and report an error. */
+            break;
+        case AC_TYPE_RESPONSE: {
+            switch (obj->type) {
+                case AC_RESPONSE_CMD_RESULT: {
+                    goto ok;
+                }
+                case AC_RESPONSE_CMD_OUT: {
+                    ac_response_cmd_out_t *v = (ac_response_cmd_out_t *) obj;
+                    if (v->sender) free(v->sender);
+                    if (v->out) free(v->out);
+                    goto ok;
+                }
+                case AC_RESPONSE_ERROR: {
+                    ac_response_error_t *v = (ac_response_error_t *) obj;
+                    if (v->message) free(v->message);
+                    goto ok;
+                }
+                case AC_RESPONSE_OK: {
+                    goto ok;
+                }
+            }
+            break;
+        }
+    }
+    LOGE("Invalid type passed to ac_obj_free function.");
+    return AC_E_INVALID_REQUEST;
+    ok:
+    {
+        free(obj);
+        return AC_E_OK;
+    };
+}
\ No newline at end of file
diff --git a/client/libacron/include/common.h b/client/libacron/include/common.h
new file mode 100644
index 0000000..89738c4
--- /dev/null
+++ b/client/libacron/include/common.h
@@ -0,0 +1,64 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#ifndef LIBAC_COMMON_H
+#define LIBAC_COMMON_H
+
+/* Library errors */
+/* OK */
+#define AC_E_OK  0
+/* The library is not initialized on that thread. */
+#define AC_E_NOT_INITIALIZED    1
+/* ac_init(): The library is already initialized on that thread. */
+#define AC_E_ALREADY_INITIALIZED    2
+/* Cannot allocate memory. */
+#define AC_E_MEMORY_ALLOCATION  3
+/* Library internal error. */
+#define AC_E_INTERNAL           4
+/* The server returns an invalid response. */
+#define AC_E_INVALID_RESPONSE    5
+/* The request is invalid. */
+#define AC_E_INVALID_REQUEST    6
+/* Network error */
+#define AC_E_NET                7
+
+/* Remote errors */
+#define AC_ER_BAD_REQUEST       400
+#define AC_ER_NOT_AUTHORIZED    401
+#define AC_ER_FORBIDDEN         403
+#define AC_ER_INTERNAL_ERROR    500
+
+/* General Structs */
+enum ac_world {
+    overworld,
+    nether,
+    end
+};
+
+typedef struct ac_vec3d {
+    double x;
+    double y;
+    double z;
+} ac_vec3d_t;
+
+typedef struct ac_vec2f {
+    double x;
+    double y;
+} ac_vec2f_t;
+
+typedef struct ac_entity {
+    char *name;
+    char *uuid;
+    ac_vec3d_t pos;
+    enum ac_world world;
+} ac_entity_t;
+
+typedef struct ac_config {
+    enum ac_world *world;
+    ac_vec3d_t *pos;
+    ac_vec2f_t *rot;
+    char *name;
+} ac_config_t;
+
+#endif /* LIBAC_COMMON_H */
diff --git a/client/libacron/include/events.h b/client/libacron/include/events.h
new file mode 100644
index 0000000..93a5184
--- /dev/null
+++ b/client/libacron/include/events.h
@@ -0,0 +1,51 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#ifndef LIBAC_EVENTS_H
+#define LIBAC_EVENTS_H
+
+#include "common.h"
+#include "ids.h"
+#include <stdint.h>
+
+/* Events */
+typedef struct ac_event {
+    uint8_t type;
+} ac_event_t;
+
+#define AC_EVENT_PLAYER_JOIN AC_ID(AC_TYPE_EVENT, 1 /* 0b0000001 */) /* 0b00000001 */
+typedef struct ac_event_player_join {
+    uint8_t type;
+    ac_entity_t player;
+} ac_event_player_join_t;
+
+#define AC_EVENT_PLAYER_DISCONNECT AC_ID(AC_TYPE_EVENT, 2 /* 0b0000010 */) /* 0b00000010 */
+typedef struct ac_event_player_disconnect {
+    uint8_t type;
+    ac_entity_t player;
+    char *reason;
+} ac_event_player_disconnect_t;
+
+#define AC_EVENT_ENTITY_DEATH AC_ID(AC_TYPE_EVENT, 3 /* 0b00000011 */) /* 0b00000011 */
+typedef struct ac_event_entity_death {
+    uint8_t type;
+    ac_entity_t entity;
+    char *message;
+} ac_event_entity_death_t;
+
+#define AC_EVENT_PLAYER_MESSAGE AC_ID(AC_TYPE_EVENT, 4 /* 0b00000100 */) /* 0b00000100 */
+typedef struct ac_event_player_message {
+    uint8_t type;
+    ac_entity_t player;
+    char *text;
+} ac_event_player_message_t;
+
+#define AC_EVENT_LAGGING AC_ID(AC_TYPE_EVENT, 5 /* 0b00000101 */) /* 0b00000101 */
+typedef struct ac_event_lagging {
+    uint8_t type;
+    int64_t ms;
+    int64_t ticks;
+} ac_event_lagging_t;
+
+#endif /* LIBAC_EVENTS_H */
diff --git a/client/libacron/include/ids.h b/client/libacron/include/ids.h
new file mode 100644
index 0000000..86fde47
--- /dev/null
+++ b/client/libacron/include/ids.h
@@ -0,0 +1,26 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#ifndef LIBAC_IDS_H
+#define LIBAC_IDS_H
+
+#define AC_TYPE_EVENT       0   /* 0b00000000 */
+#define AC_TYPE_REQUEST     64  /* 0b01000000 */
+#define AC_TYPE_RESPONSE    128 /* 0b10000000 */
+
+#define AC_ID(type, num) type + num
+
+#define AC_IS_EVENT(type) (type & 192) == AC_TYPE_EVENT
+#define AC_IS_REQUEST(type) (type & 192) == AC_TYPE_REQUEST
+#define AC_IS_RESPONSE(type) (type & 192) == AC_TYPE_RESPONSE
+
+#include <stdint.h>
+
+typedef struct ac_obj {
+    uint8_t type;
+} ac_obj_t;
+
+int ac_object_free(ac_obj_t *obj);
+
+#endif /* LIBAC_IDS_H */
diff --git a/client/libacron/include/libac.h b/client/libacron/include/libac.h
new file mode 100644
index 0000000..80734dc
--- /dev/null
+++ b/client/libacron/include/libac.h
@@ -0,0 +1,34 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#ifndef LIBAC_LIBAC_H
+#define LIBAC_LIBAC_H
+
+#include "common.h"
+#include "events.h"
+#include "net.h"
+#include "requests.h"
+#include "ids.h"
+
+#include <json-c/json_tokener.h>
+#include <stdio.h>
+
+typedef struct libac_config {
+    FILE *out;
+    json_tokener *tok;
+} libac_config_t;
+
+/**
+ * Initialize libac for the calling thread.
+ * @return 0 on success.
+ */
+int ac_init(const libac_config_t *config);
+
+/**
+ * Destroy libac configuration for the calling thread.
+ * @return 0 on success.
+ */
+int ac_free(void);
+
+#endif /* LIBAC_LIBAC_H */
diff --git a/client/libacron/include/net.h b/client/libacron/include/net.h
new file mode 100644
index 0000000..5b10470
--- /dev/null
+++ b/client/libacron/include/net.h
@@ -0,0 +1,29 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#ifndef LIBAC_NET_H
+#define LIBAC_NET_H
+
+#include "common.h"
+#include "events.h"
+#include "requests.h"
+
+/* Connection */
+
+typedef struct ac_connection_parameters {
+    /**
+     * ws://host:port/ws?id=id&token=token
+     * Currently wss is not supported.
+     * Port must be supplied, or libac will connect to port zero.
+     */
+    char *url;
+} ac_connection_parameters_t;
+
+int ac_connect(ac_connection_parameters_t parameters, void **out);
+
+int ac_disconnect(void *connection);
+
+int ac_receive(void *connection, ac_obj_t **response);
+
+#endif /* LIBAC_NET_H */
diff --git a/client/libacron/include/requests.h b/client/libacron/include/requests.h
new file mode 100644
index 0000000..40742e0
--- /dev/null
+++ b/client/libacron/include/requests.h
@@ -0,0 +1,71 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#ifndef LIBAC_REQUESTS_H
+#define LIBAC_REQUESTS_H
+
+#include "common.h"
+#include "ids.h"
+#include <stdbool.h>
+
+/* Responses */
+typedef struct ac_response {
+    uint8_t type;
+    int id;
+} ac_response_t;
+
+#define AC_RESPONSE_ERROR    AC_ID(AC_TYPE_RESPONSE, 1 /* 0b00000001 */) /* 0b10000001 */
+typedef struct ac_response_error {
+    uint8_t type;
+    int id;
+    int code;
+    char *message;
+} ac_response_error_t;
+
+#define AC_RESPONSE_OK   AC_ID(AC_TYPE_RESPONSE, 2 /* 0b00000010 */) /* 0b10000010 */
+typedef struct ac_response_ok {
+    uint8_t type;
+    int id;
+} ac_response_ok_t;
+
+#define AC_RESPONSE_CMD_OUT  AC_ID(AC_TYPE_RESPONSE, 3 /* 0b00000011 */) /* 0b10000011 */
+typedef struct ac_response_cmd_out {
+    uint8_t type;
+    int id;
+    char *sender;
+    char *out;
+} ac_response_cmd_out_t;
+
+#define AC_RESPONSE_CMD_RESULT   AC_ID(AC_TYPE_RESPONSE, 4 /* 0b00000100 */) /* 0b10000100 */
+typedef struct ac_response_cmd_result {
+    uint8_t type;
+    int id;
+    int result;
+    bool success;
+} ac_response_cmd_result_t;
+
+/* Requests */
+typedef struct ac_request {
+    uint8_t type;
+    int id;
+} ac_request_t;
+
+#define AC_REQUEST_CMD   AC_ID(AC_TYPE_REQUEST, 1 /* 0b00000001 */) /* 0b01000001 */
+typedef struct ac_request_cmd {
+    uint8_t type;
+    int id;
+    ac_config_t  *config;
+    char *cmd;
+} ac_request_cmd_t;
+
+#define AC_REQUEST_SET_CONFIG    AC_ID(AC_TYPE_REQUEST, 2 /* 0b00000010 */) /* 0b01000010 */
+typedef struct ac_request_set_config {
+    uint8_t type;
+    int id;
+    ac_config_t config;
+} ac_request_set_config_t;
+
+int ac_request(void *connection, const ac_request_t *request);
+
+#endif /* LIBAC_REQUESTS_H */
diff --git a/client/libacron/library.c b/client/libacron/library.c
new file mode 100644
index 0000000..dfc45e2
--- /dev/null
+++ b/client/libacron/library.c
@@ -0,0 +1,44 @@
+#include "libac.h"
+#include "config.h"
+#include "helpers.h"
+
+#include <stdlib.h>
+
+_Thread_local struct libac_config *config = NULL;
+
+int ac_init(const libac_config_t *c) {
+    if (config) {
+        return AC_E_ALREADY_INITIALIZED;
+    }
+
+    int r;
+    if ((r = SALLOC(libac_config_t, &config))) {
+        return r;
+    }
+
+    if (c->tok) {
+        config->tok = c->tok;
+    } else {
+        if (!(config->tok = json_tokener_new())) {
+            r = AC_E_MEMORY_ALLOCATION;
+            goto fail;
+        }
+    }
+    if (c->out) {
+        config->out = c->out;
+    }
+    return AC_E_OK;
+    fail:
+    ac_free();
+    return r;
+}
+
+int ac_free(void) {
+    AC_CHECK_INIT;
+    if (config->tok) {
+        json_tokener_free(config->tok);
+        config->tok = NULL;
+    }
+    free(config);
+    config = NULL;
+}
\ No newline at end of file
diff --git a/client/libacron/net.c b/client/libacron/net.c
new file mode 100644
index 0000000..51a99af
--- /dev/null
+++ b/client/libacron/net.c
@@ -0,0 +1,306 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#include "config.h"
+#include "net.h"
+#include "connection.h"
+#include "log.h"
+#include "helpers.h"
+#include "serializer.h"
+
+/* TODO: wic logging is not yet supported */
+#include "wic.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+
+static void on_open_handler(struct wic_inst *inst) {
+    struct ac_connection *conn = wic_get_app(inst);
+    conn->established = true;
+}
+
+static void on_send_handler(struct wic_inst *inst,
+                            const void *data,
+                            size_t size,
+                            enum wic_buffer type) {
+    struct ac_connection *conn = wic_get_app(inst);
+    size_t pos;
+    ssize_t retval;
+
+    for (pos = 0U; pos < size; pos += retval) {
+        size_t n = size - pos;
+        LOGDV("write(%d, %p[%u, %u])", conn->fd, data, pos, n);
+        retval = write(conn->fd, &data[pos], (int) n);
+        if (retval <= 0) {
+            /* There's no way to abort the process. */
+            int e = errno;
+            LOGEV("Cannot write to socket: %s (%d).",
+                  strerror2(errno),
+                  e);
+            break;
+        }
+    }
+    free((void *) data);
+}
+
+static void *on_buffer_handler(struct wic_inst *inst,
+                               size_t min_size,
+                               enum wic_buffer type,
+                               size_t *max_size) {
+    void *buf;
+    if ((alloc(NULL,
+               1,
+               *max_size = (min_size ? min_size : 1024),
+               false,
+               &buf))) {
+        return NULL;
+    }
+    return buf;
+}
+
+static bool on_message_handler(struct wic_inst *inst,
+                               enum wic_encoding encoding,
+                               bool fin,
+                               const char *data,
+                               uint16_t size) {
+    struct ac_connection *conn = wic_get_app(inst);
+    if (encoding != WIC_ENCODING_UTF8) {
+        LOGE("Invalid encoding received from server. Only text frames are supported.");
+        return true;
+    }
+    /* TODO: Only parse when fin = true? */
+    struct ac_result *res = &conn->result;
+    int r;
+    if ((r = deserialize(data, size, &res->obj))) {
+        if (r == AC_E_SERIALIZER_CONTINUE) {
+            if (fin) {
+                serializer_finalize();
+                LOGE("Server returned an incomplete response.");
+                res->res = AC_E_INVALID_RESPONSE;
+            } else {
+                res->res = AC_E_OK;
+            }
+        } else {
+            res->res = r;
+        }
+    } else {
+        res->has_result = true;
+        res->res = r;
+    }
+    LOGDV("Post deserializing: { has_result = %d, res = %d, obj = %p }",
+          res->has_result,
+          res->res,
+          res->obj);
+
+    return true;
+}
+
+int ac_connect(ac_connection_parameters_t parameters, void **out) {
+    AC_CHECK_INIT;
+    struct ac_connection *conn;
+    int r;
+    if ((r = SALLOC(struct ac_connection, &conn))) {
+        return r;
+    }
+    int s;
+    static uint8_t rx[1000];
+    struct wic_inst *inst = &conn->inst;
+    struct wic_init_arg arg = {0};
+
+    arg.rx = rx;
+    arg.rx_max = sizeof(rx);
+
+    arg.on_send = on_send_handler;
+    arg.on_open = on_open_handler;
+    arg.on_message = on_message_handler;
+    arg.on_buffer = on_buffer_handler;
+
+    arg.app = &s;
+    arg.url = parameters.url;
+    arg.role = WIC_ROLE_CLIENT;
+
+    if (!wic_init(inst, &arg)) {
+        LOGE("wic_init");
+        free(conn);
+        return AC_E_INTERNAL;
+    }
+    inst->app = conn;
+
+    struct addrinfo *res;
+    char service[6];
+
+    const enum wic_schema schema = wic_get_url_schema(inst);
+    const uint16_t port = wic_get_url_port(inst);
+    snprintf(service, 6, "%u", port);
+    const char *host = wic_get_url_hostname(inst);
+
+    switch (schema) {
+        case WIC_SCHEMA_WS:
+            break;
+        case WIC_SCHEMA_WSS:
+            LOGE("WSS is not supported yet.");
+            free(conn);
+            return AC_E_INVALID_REQUEST;
+        default:
+            LOGE("Unsupported protocol. The URL must be ws://");
+            free(conn);
+            return AC_E_INVALID_REQUEST;
+    }
+
+    if ((r = getaddrinfo(host, service, NULL, &res))) {
+        LOGEV("Resolve host: %s.", gai_strerror(r));
+        r = AC_E_NET;
+        free(conn);
+        return r;
+    }
+
+    int fd;
+    if ((fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) <= 0) {
+        const int e = errno;
+        LOGEV("Cannot create socket: %s (%d).",
+              strerror2(e),
+              e);
+        freeaddrinfo(res);
+        free(conn);
+        return AC_E_NET;
+    }
+    if (connect(fd, res->ai_addr, res->ai_addrlen) < 0) {
+        const int e = errno;
+        LOGEV("Cannot connect to socket: %s (%d).",
+              strerror2(e),
+              e);
+        close(fd);
+        freeaddrinfo(res);
+        free(conn);
+        return AC_E_NET;
+    }
+    freeaddrinfo(res);
+
+    conn->fd = fd;
+    if (wic_start(inst) != WIC_STATUS_SUCCESS) {
+        LOGE("Cannot start the WIC client.");
+        close(fd);
+        free(conn);
+        return AC_E_NET;
+    }
+
+    /* Wait until established (ready to send). */
+    while (!conn->established) {
+        ac_obj_t *obj = NULL;
+        r = ac_receive(conn, &obj);
+        if (obj) {
+            LOGW("Received an object before connection is established. Dropping.");
+            ac_object_free(obj);
+        }
+        if (r) {
+            ac_disconnect(conn);
+            return r;
+        }
+    }
+    *out = conn;
+    return AC_E_OK;
+}
+
+int ac_disconnect(void *connection) {
+    AC_CHECK_INIT;
+    struct ac_connection *conn = connection;
+    if (!conn->fd) {
+        LOGE("Trying to disconnect an already disconnected connection.");
+        return AC_E_INVALID_REQUEST;
+    }
+    LOGD("Disconnecting...");
+    wic_close(&conn->inst);
+    close(conn->fd);
+    free(conn);
+    return AC_E_OK;
+}
+
+int ac_receive(void *connection, ac_obj_t **response) {
+    AC_CHECK_INIT;
+    struct ac_connection *conn = connection;
+    struct wic_inst *inst = &conn->inst;
+
+    static uint8_t buffer[1000U];
+    ssize_t bytes;
+    size_t retval, pos;
+
+    if ((bytes = recv(conn->fd, buffer, sizeof(buffer), 0)) <= 0) {
+        LOGDV("recv(%d) = %d", conn->fd, bytes);
+        if (bytes < 0) {
+            const int e = errno;
+            LOGEV("Failed to receive from socket : %s (%d).",
+                  strerror2(e),
+                  e);
+        } else {
+            LOGI("Peer abnormally shutdown.");
+        }
+        wic_close_with_reason(inst, WIC_CLOSE_ABNORMAL_2, NULL, 0);
+        return AC_E_NET;
+    }
+    LOGDV("recv(%d) = %d", conn->fd, bytes);
+
+    /* In case the deserializer does not run at all. */
+    memset(&conn->result, 0, sizeof(struct ac_result));
+    for (pos = 0U; pos < bytes; pos += retval) {
+        retval = wic_parse(inst, &buffer[pos], bytes - pos);
+        if (wic_get_state(inst) == WIC_STATE_CLOSED) {
+            LOGE("Connection closed.");
+            return AC_E_NET;
+        }
+    }
+
+    struct ac_result *res = &conn->result;
+    LOGDV("res { has_result = %d, res = %d, obj = %p }",
+          res->has_result,
+          res->res,
+          res->obj);
+    *response = NULL;
+    if (res->has_result) {
+        if (res->res) {
+            return res->res;
+        } else {
+            *response = res->obj;
+            return AC_E_OK;
+        }
+    } else {
+        *response = NULL;
+    }
+
+    return AC_E_OK;
+}
+
+int ac_request(void *connection, const ac_request_t *request) {
+    AC_CHECK_INIT;
+    struct ac_connection *conn = connection;
+    struct wic_inst *inst = &conn->inst;
+    if (wic_get_state(inst) != WIC_STATE_OPEN) {
+        LOGE("Invalid state.");
+        return AC_E_INVALID_REQUEST;
+    }
+    int r;
+    json_object *obj;
+    if ((r = serialize_request(request, &obj))) {
+        return r;
+    }
+    const char *str;
+    size_t len;
+    if (!(str = json_object_to_json_string_length(obj, JSON_C_TO_STRING_PLAIN, &len))) {
+        json_object_put(obj);
+        LOGE("Cannot serialize JSON.");
+        return AC_E_INTERNAL;
+    }
+    if (wic_send_text(inst, true, str, len) != WIC_STATUS_SUCCESS) {
+        LOGE("Cannot send.");
+        json_object_put(obj);
+        return AC_E_NET;
+    }
+    json_object_put(obj);
+    return AC_E_OK;
+}
diff --git a/client/libacron/private/config.h b/client/libacron/private/config.h
new file mode 100644
index 0000000..3b670df
--- /dev/null
+++ b/client/libacron/private/config.h
@@ -0,0 +1,17 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#ifndef LIBAC_CONFIG_H
+#define LIBAC_CONFIG_H
+
+#include "libac.h"
+
+#include <json-c/json_tokener.h>
+#include <stdio.h>
+
+extern _Thread_local struct libac_config *config;
+
+#define AC_CHECK_INIT do { if (!config) return AC_E_NOT_INITIALIZED; } while(0)
+
+#endif /* LIBAC_CONFIG_H */
diff --git a/client/libacron/private/connection.h b/client/libacron/private/connection.h
new file mode 100644
index 0000000..1c1567f
--- /dev/null
+++ b/client/libacron/private/connection.h
@@ -0,0 +1,28 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#ifndef LIBAC_CONNECTION_H
+#define LIBAC_CONNECTION_H
+
+#include "wic.h"
+#include "libac.h"
+#include <stdbool.h>
+
+struct ac_result {
+    bool has_result;
+    int res;
+    ac_obj_t *obj;
+};
+
+struct ac_connection {
+    ac_connection_parameters_t parameters;
+    struct wic_inst inst;
+    int fd;
+    bool established;
+    /* Result from message handler.
+     * Message handling will happen at the same thread as ac_receive (lib wic). */
+    struct ac_result result;
+};
+
+#endif /* LIBAC_CONNECTION_H */
diff --git a/client/libacron/private/helpers.c b/client/libacron/private/helpers.c
new file mode 100644
index 0000000..4d4f3c8
--- /dev/null
+++ b/client/libacron/private/helpers.c
@@ -0,0 +1,64 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#include "helpers.h"
+#include "log.h"
+#include "common.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+
+int alloc(void *existing,
+            unsigned int count,
+            unsigned int bytes,
+            bool zero_out,
+            void **out) {
+    const unsigned int size = count * bytes;
+    void *ptr;
+    if (!(ptr = realloc(existing, size))) {
+        const int e = errno;
+        LOGEV("Cannot %sallocate %d bytes of memory: %s (%d).",
+                existing ? "re" : "",
+                size,
+                strerror2(e),
+                e);
+        return AC_E_MEMORY_ALLOCATION;
+    }
+    if (!existing && zero_out) {
+        memset(ptr, 0, size);
+    }
+    *out = ptr;
+    return AC_E_OK;
+}
+
+int strdup2(const char *str, char **out) {
+    char *str2;
+    if (!(str2 = strdup(str))) {
+        const int e = errno;
+        LOGEV("Cannot duplicate string '%s': %s (%d).",
+                str,
+                strerror2(e),
+                e);
+        return AC_E_MEMORY_ALLOCATION;
+    }
+    *out = str2;
+    return AC_E_OK;
+}
+
+static _Thread_local char err_buf[1024];
+
+char *strerror2(int errnum) {
+#ifdef WIN32
+    /* Win32 strerror(3) is thread-safe. */
+    return strerror(errnum);
+#else
+    int r;
+    if ((strerror_r(errnum, err_buf, sizeof(err_buf) / sizeof(char)))) {
+        snprintf(err_buf, 1024, "%d (%d)", errnum, r);
+    }
+    return err_buf;
+#endif
+}
\ No newline at end of file
diff --git a/client/libacron/private/helpers.h b/client/libacron/private/helpers.h
new file mode 100644
index 0000000..20dfeec
--- /dev/null
+++ b/client/libacron/private/helpers.h
@@ -0,0 +1,22 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#ifndef LIBAC_HELPERS_H
+#define LIBAC_HELPERS_H
+
+#include <stdbool.h>
+
+#define SALLOC(s, out) alloc(NULL, 1, sizeof(s), true, (void **) out)
+
+int alloc(void *existing,
+            unsigned int count,
+            unsigned int bytes,
+            bool zero_out,
+            void **out);
+
+int strdup2(const char *str, char **out);
+
+char *strerror2(int errnum);
+
+#endif /* LIBAC_HELPERS_H */
diff --git a/client/libacron/private/log.c b/client/libacron/private/log.c
new file mode 100644
index 0000000..b5a246a
--- /dev/null
+++ b/client/libacron/private/log.c
@@ -0,0 +1,52 @@
+/*
+ * Created by yuuta on 1/1/22.
+ */
+
+#include "log.h"
+#include "config.h"
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <assert.h>
+
+void g_log(enum log_level level,
+                  const char *file,
+                  int line,
+                  const char *format,
+                  ...) {
+    if (config == NULL || config->out == NULL) {
+        return;
+    }
+    FILE *stream = config->out;
+    switch (level) {
+        case log_fetal:
+            fprintf(stream, "F");
+            break;
+        case log_error:
+            fprintf(stream, "E");
+            break;
+        case log_warn:
+            fprintf(stream, "W");
+            break;
+        case log_info:
+            fprintf(stream, "I");
+            break;
+        case log_debug:
+#ifdef DEBUG
+            fprintf(stream, "D");
+            break;
+#else
+            return;
+#endif
+        default:
+            fprintf(stderr, "Unknown log level: %d.\n", level);
+            assert(0);
+    }
+    fprintf(stream, "[%s:%d]: ",
+            file, line);
+    va_list list;
+    va_start(list, format);
+    vfprintf(stream, format, list);
+    va_end(list);
+    fprintf(stream, "\n");
+}
diff --git a/client/libacron/private/log.h b/client/libacron/private/log.h
new file mode 100644
index 0000000..7d41fbc
--- /dev/null
+++ b/client/libacron/private/log.h
@@ -0,0 +1,42 @@
+/*
+ * Created by yuuta on 1/1/22.
+ */
+
+#ifndef LOG_H
+#define LOG_H
+
+enum log_level {
+    log_fetal = 1,
+    log_error = 2,
+    log_warn = 3,
+    log_info = 4,
+    log_debug = 5
+};
+
+void g_log(enum log_level level,
+           const char *file,
+           int line,
+           const char *format,
+           ...);
+
+#define LOGF(X) g_log(log_fetal, __FUNCTION__, __LINE__, X)
+
+#define LOGFV(X, ...) g_log(log_fetal, __FUNCTION__, __LINE__, X, __VA_ARGS__)
+
+#define LOGE(X) g_log(log_error, __FUNCTION__, __LINE__, X)
+
+#define LOGEV(X, ...) g_log(log_error, __FUNCTION__, __LINE__, X, __VA_ARGS__)
+
+#define LOGW(X) g_log(log_warn, __FUNCTION__, __LINE__, X)
+
+#define LOGWV(X, ...) g_log(log_warn, __FUNCTION__, __LINE__, X, __VA_ARGS__)
+
+#define LOGI(X) g_log(log_info, __FUNCTION__, __LINE__, X)
+
+#define LOGIV(X, ...) g_log(log_info, __FUNCTION__, __LINE__, X, __VA_ARGS__)
+
+#define LOGD(X) g_log(log_debug, __FUNCTION__, __LINE__, X)
+
+#define LOGDV(X, ...) g_log(log_debug, __FUNCTION__, __LINE__, X, __VA_ARGS__)
+
+#endif /* LOG_H */
diff --git a/client/libacron/private/serializer.c b/client/libacron/private/serializer.c
new file mode 100644
index 0000000..c34c81f
--- /dev/null
+++ b/client/libacron/private/serializer.c
@@ -0,0 +1,572 @@
+/*
+ * Created by yuuta on 7/13/22.
+ */
+
+#include "libac.h"
+#include "config.h"
+#include "serializer.h"
+#include "helpers.h"
+#include "log.h"
+
+#include <json-c/json_object.h>
+#include <json-c/json_tokener.h>
+#include <json-c/json_util.h>
+#include <string.h>
+
+static int assert_type(const json_object *obj, const json_type type, const char *location) {
+    if (json_object_is_type(obj, type)) {
+        return AC_E_OK;
+    }
+    LOGEV("Cannot deserialize JSON at '%s': It should be a(n) %s, but it is a(n) %s.",
+          location,
+          json_type_to_name(type),
+          json_type_to_name(json_object_get_type(obj)));
+    return AC_E_INVALID_RESPONSE;
+}
+
+static int get_child(const json_object *obj,
+                     const char *key,
+                     const json_type type,
+                     const bool mandatory,
+                     json_object **out) {
+    if (!json_object_object_get_ex(obj, key, out)) {
+        if (!mandatory) {
+            *out = NULL;
+            return AC_E_OK;
+        }
+        LOGEV("Cannot deserialize JSON: A mandatory child '%s' is missing.",
+              key);
+        return AC_E_INVALID_RESPONSE;
+    }
+    return assert_type(*out, type, key);
+}
+
+static int deserialize_pre(const char *string,
+                           unsigned int len,
+                           json_object **out_json,
+                           const char **out_type,
+                           bool id_mandatory,
+                           bool *out_has_id,
+                           int32_t *out_id) {
+    AC_CHECK_INIT;
+    json_object *obj = NULL;
+    if (!(obj = json_tokener_parse_ex(config->tok,
+                                      string,
+                                      (int) len))) {
+        enum json_tokener_error err = json_tokener_get_error(config->tok);
+        if (err == json_tokener_continue) {
+            return AC_E_SERIALIZER_CONTINUE;
+        }
+        LOGEV("Cannot parse JSON response '%s': %s.",
+              string,
+              json_tokener_error_desc(err));
+        json_tokener_reset(config->tok);
+        return AC_E_INVALID_RESPONSE;
+    }
+    int r;
+    if ((r = assert_type(obj, json_type_object, "."))) {
+        json_object_put(obj);
+        return r;
+    }
+    json_object *arg;
+    if ((r = get_child(obj, "type", json_type_string, true, &arg))) {
+        json_object_put(obj);
+        return r;
+    }
+    *out_json = obj;
+    *out_type = json_object_get_string(arg);
+    if ((r = get_child(obj, "id", json_type_int, id_mandatory, &arg))) {
+        json_object_put(obj);
+        *out_has_id = false;
+        return r;
+    } else {
+        *out_id = json_object_get_int(arg);
+        /* If is_mandatory is false, get_child will return 0 even it arg == NULL. */
+        *out_has_id = arg;
+    }
+    return AC_E_OK;
+}
+
+static int deserialize_entity(const json_object *json, ac_entity_t *entity) {
+    int r;
+    json_object *arg;
+    if ((r = get_child(json, "name", json_type_string, true, &arg))) {
+        return r;
+    }
+    if ((r = strdup2(json_object_get_string(arg), &entity->name))) {
+        return r;
+    }
+
+    if ((r = get_child(json, "uuid", json_type_string, true, &arg))) {
+        return r;
+    }
+    if ((r = strdup2(json_object_get_string(arg), &entity->uuid))) {
+        return r;
+    }
+
+    if ((r = get_child(json, "world", json_type_string, false, &arg))) {
+        return r;
+    }
+    if (arg) {
+        const char *world_str = json_object_get_string(arg);
+        if (!strcmp("overworld", world_str)) {
+            entity->world = overworld;
+        } else if (!strcmp("nether", world_str)) {
+            entity->world = nether;
+        } else if (!strcmp("end", world_str)) {
+            entity->world = end;
+        } else {
+            LOGEV("Server returned an invalid world: %s.", world_str);
+            return r;
+        }
+    }
+
+    json_object *vec3d;
+    if ((r = get_child(json, "pos", json_type_object, true, &vec3d))) {
+        return r;
+    }
+    json_object *d;
+    if ((r = get_child(vec3d, "x", json_type_double, true, &d))) {
+        return r;
+    }
+    entity->pos.x = json_object_get_double(d);
+
+    if ((r = get_child(vec3d, "y", json_type_double, true, &d))) {
+        return r;
+    }
+    entity->pos.y = json_object_get_double(d);
+
+    if ((r = get_child(vec3d, "z", json_type_double, true, &d))) {
+        return r;
+    }
+    entity->pos.z = json_object_get_double(d);
+    return AC_E_OK;
+}
+
+static int deserialize_response(json_object *obj, const char *type_str, const int id, ac_response_t **out) {
+    int r;
+
+    if (!strcmp("ok", type_str)) {
+        ac_response_ok_t *ok;
+        if ((r = SALLOC(ac_response_t, &ok))) {
+            goto fail;
+        }
+        ok->type = AC_RESPONSE_OK;
+        ok->id = id;
+
+        *out = (ac_response_t *) ok;
+    } else if (!strcmp("error", type_str)) {
+        ac_response_error_t *error;
+        if ((r = SALLOC(ac_response_error_t, &error))) {
+            goto fail;
+        }
+        error->type = AC_RESPONSE_ERROR;
+        error->id = id;
+        json_object *arg;
+
+        if ((r = get_child(obj, "code", json_type_int, true, &arg))) {
+            ac_object_free((ac_obj_t *) error);
+            goto fail;
+        }
+        error->code = json_object_get_int(arg);
+
+        if ((r = get_child(obj, "message", json_type_string, true, &arg))) {
+            ac_object_free((ac_obj_t *) error);
+            goto fail;
+        }
+        if ((r = strdup2(json_object_get_string(arg), &error->message))) {
+            ac_object_free((ac_obj_t *) error);
+            goto fail;
+        }
+
+        *out = (ac_response_t *) error;
+    } else if (!strcmp("cmd_out", type_str)) {
+        ac_response_cmd_out_t *o;
+        if ((r = SALLOC(ac_response_cmd_out_t, &o))) {
+            goto fail;
+        }
+        o->type = AC_RESPONSE_CMD_OUT;
+        o->id = id;
+        json_object *arg;
+
+        if ((r = get_child(obj, "sender", json_type_string, true, &arg))) {
+            ac_object_free((ac_obj_t *) o);
+            goto fail;
+        }
+        if ((r = strdup2(json_object_get_string(arg), &o->sender))) {
+            ac_object_free((ac_obj_t *) o);
+            goto fail;
+        }
+
+        if ((r = get_child(obj, "out", json_type_string, true, &arg))) {
+            ac_object_free((ac_obj_t *) o);
+            goto fail;
+        }
+        if ((r = strdup2(json_object_get_string(arg), &o->out))) {
+            ac_object_free((ac_obj_t *) o);
+            goto fail;
+        }
+
+        *out = (ac_response_t *) o;
+    } else if (!strcmp("cmd_result", type_str)) {
+        ac_response_cmd_result_t *res;
+        if ((r = SALLOC(ac_response_cmd_result_t, &res))) {
+            goto fail;
+        }
+        res->type = AC_RESPONSE_CMD_RESULT;
+        res->id = id;
+        json_object *arg;
+
+        if ((r = get_child(obj, "result", json_type_int, true, &arg))) {
+            ac_object_free((ac_obj_t *) res);
+            goto fail;
+        }
+        res->result = json_object_get_int(arg);
+
+        if ((r = get_child(obj, "success", json_type_boolean, true, &arg))) {
+            ac_object_free((ac_obj_t *) res);
+            goto fail;
+        }
+        res->success = json_object_get_boolean(arg);
+
+        *out = (ac_response_t *) res;
+    } else {
+        LOGEV("Invalid response type: '%s'.", type_str);
+        r = AC_E_INVALID_RESPONSE;
+        goto fail;
+    }
+    return AC_E_OK;
+    fail:
+    if (obj) {
+        json_object_put(obj);
+    }
+    return r;
+}
+
+static int deserialize_event(json_object *obj, const char *type_str, ac_event_t **out) {
+    LOGDV("Deserializing event type '%s'", type_str);
+    int r;
+
+    if (!strcmp("join", type_str)) {
+        ac_event_player_join_t *join;
+        if ((r = SALLOC(ac_event_player_join_t, &join))) {
+            goto fail;
+        }
+        join->type = AC_EVENT_PLAYER_JOIN;
+
+        json_object *arg;
+        if ((r = get_child(obj, "player", json_type_object, true, &arg))) {
+            ac_object_free((ac_obj_t *) join);
+            goto fail;
+        }
+        if ((r = deserialize_entity(arg, &join->player))) {
+            ac_object_free((ac_obj_t *) join);
+            goto fail;
+        }
+
+        *out = (ac_event_t *) join;
+    } else if (!strcmp("disconnect", type_str)) {
+        ac_event_player_disconnect_t *disconnect;
+        if ((r = SALLOC(ac_event_player_disconnect_t, &disconnect))) {
+            goto fail;
+        }
+        disconnect->type = AC_EVENT_PLAYER_DISCONNECT;
+
+        json_object *arg;
+        if ((r = get_child(obj, "player", json_type_object, true, &arg))) {
+            ac_object_free((ac_obj_t *) disconnect);
+            goto fail;
+        }
+        if ((r = deserialize_entity(arg, &disconnect->player))) {
+            ac_object_free((ac_obj_t *) disconnect);
+            goto fail;
+        }
+
+        if ((r = get_child(obj, "reason", json_type_string, true, &arg))) {
+            ac_object_free((ac_obj_t *) disconnect);
+            goto fail;
+        }
+        if ((r = strdup2(json_object_get_string(arg), &disconnect->reason))) {
+            ac_object_free((ac_obj_t *) disconnect);
+            goto fail;
+        }
+
+        *out = (ac_event_t *) disconnect;
+    } else if (!strcmp("message", type_str)) {
+        ac_event_player_message_t *message;
+        if ((r = SALLOC(ac_event_player_message_t, &message))) {
+            goto fail;
+        }
+        message->type = AC_EVENT_PLAYER_MESSAGE;
+
+        json_object *arg;
+        if ((r = get_child(obj, "player", json_type_object, true, &arg))) {
+            ac_object_free((ac_obj_t *) message);
+            goto fail;
+        }
+        if ((r = deserialize_entity(arg, &message->player))) {
+            ac_object_free((ac_obj_t *) message);
+            goto fail;
+        }
+
+        if ((r = get_child(obj, "text", json_type_string, true, &arg))) {
+            ac_object_free((ac_obj_t *) message);
+            goto fail;
+        }
+        if ((r = strdup2(json_object_get_string(arg), &message->text))) {
+            ac_object_free((ac_obj_t *) message);
+            goto fail;
+        }
+
+        *out = (ac_event_t *) message;
+    } else if (!strcmp("death", type_str)) {
+        ac_event_entity_death_t *death;
+        if ((r = SALLOC(ac_event_entity_death_t, &death))) {
+            goto fail;
+        }
+        death->type = AC_EVENT_ENTITY_DEATH;
+
+        json_object *arg;
+        if ((r = get_child(obj, "entity", json_type_object, true, &arg))) {
+            ac_object_free((ac_obj_t *) death);
+            goto fail;
+        }
+        if ((r = deserialize_entity(arg, &death->entity))) {
+            ac_object_free((ac_obj_t *) death);
+            goto fail;
+        }
+
+        if ((r = get_child(obj, "message", json_type_string, true, &arg))) {
+            ac_object_free((ac_obj_t *) death);
+            goto fail;
+        }
+        if ((r = strdup2(json_object_get_string(arg), &death->message))) {
+            ac_object_free((ac_obj_t *) death);
+            goto fail;
+        }
+
+        *out = (ac_event_t *) death;
+    } else if (!strcmp("lagging", type_str)) {
+        ac_event_lagging_t *lagging;
+        if ((r = SALLOC(ac_event_lagging_t, &lagging))) {
+            goto fail;
+        }
+        lagging->type = AC_EVENT_LAGGING;
+
+        json_object *arg;
+        if ((r = get_child(obj, "ms", json_type_int, true, &arg))) {
+            goto fail;
+        }
+        lagging->ms = json_object_get_int64(arg);
+
+        if ((r = get_child(obj, "ticks", json_type_int, true, &arg))) {
+            goto fail;
+        }
+        lagging->ticks = json_object_get_int64(arg);
+
+        *out = (ac_event_t *) lagging;
+    } else {
+        LOGEV("Invalid event type: '%s'.", type_str);
+        r = AC_E_INVALID_RESPONSE;
+        goto fail;
+    }
+
+    return AC_E_OK;
+    fail:
+    if (obj) {
+        json_object_put(obj);
+    }
+    return r;
+}
+
+int deserialize(const char *string, unsigned int len, ac_obj_t **out) {
+    AC_CHECK_INIT;
+    json_object *obj;
+    const char *type_str;
+    int id;
+    bool has_id;
+    int r;
+
+    if ((r = deserialize_pre(string,
+                             len,
+                             &obj,
+                             &type_str,
+                             false,
+                             &has_id,
+                             &id))) {
+        return r;
+    }
+
+    if (has_id) {
+        return deserialize_response(obj, type_str, id, (ac_response_t **) out);
+    } else {
+        return deserialize_event(obj, type_str, (ac_event_t **) out);
+    }
+}
+
+static int json_add(json_object *obj, const char *key, json_object *val) {
+    if (!val) {
+        LOGEV("Cannot initialize JSON child '%s'.", key);
+        return AC_E_MEMORY_ALLOCATION;
+    }
+    if ((json_object_object_add(obj, key, val))) {
+        LOGEV("Cannot put '%s' to the JSON object.", key);
+        json_object_put(val);
+        return AC_E_MEMORY_ALLOCATION;
+    }
+    return AC_E_OK;
+}
+
+static int serialize_config(const ac_config_t *c, json_object *obj) {
+    int r;
+    if (c->pos) {
+        ac_vec3d_t p = *c->pos;
+        json_object *pos;
+        if (!(pos = json_object_new_object())) {
+            LOGE("Cannot initialize a new JSON object.");
+            return AC_E_MEMORY_ALLOCATION;
+        }
+        if ((r = json_add(pos, "x", json_object_new_double(p.x)))) {
+            json_object_put(pos);
+            return r;
+        }
+        if ((r = json_add(pos, "y", json_object_new_double(p.y)))) {
+            json_object_put(pos);
+            return r;
+        }
+        if ((r = json_add(pos, "z", json_object_new_double(p.z)))) {
+            json_object_put(pos);
+            return r;
+        }
+        if ((r = json_add(obj, "pos", pos))) {
+            return r;
+        }
+    }
+    if (c->world) {
+        enum ac_world world = *c->world;
+        const char *str;
+        switch (world) {
+            case overworld:
+                str = "overworld";
+                break;
+            case nether:
+                str = "nether";
+                break;
+            case end:
+                str = "end";
+                break;
+            default:
+                LOGE("Invalid world supplied.");
+                return AC_E_INVALID_REQUEST;
+        }
+        if ((r = json_add(obj, "world", json_object_new_string(str)))) {
+            return r;
+        }
+    }
+    if (c->name) {
+        if ((r = json_add(obj, "name", json_object_new_string(c->name)))) {
+            return r;
+        }
+    }
+    if (c->rot) {
+        ac_vec2f_t t = *c->rot;
+        json_object *rot;
+        if (!(rot = json_object_new_object())) {
+            LOGE("Cannot initialize a new JSON object.");
+            return AC_E_MEMORY_ALLOCATION;
+        }
+        if ((r = json_add(rot, "x", json_object_new_double(t.x)))) {
+            json_object_put(rot);
+            return r;
+        }
+        if ((r = json_add(rot, "y", json_object_new_double(t.y)))) {
+            json_object_put(rot);
+            return r;
+        }
+        if ((r = json_add(obj, "rot", rot))) {
+            return r;
+        }
+    }
+    return AC_E_OK;
+}
+
+int serialize_request(const ac_request_t *req, json_object **out) {
+    AC_CHECK_INIT;
+    if ((req->type & 192) != AC_TYPE_REQUEST) {
+        LOGE("Invalid argument to serialize_request. It should be a request.");
+        return AC_E_INVALID_REQUEST;
+    }
+    json_object *obj;
+    if (!(obj = json_object_new_object())) {
+        LOGE("Cannot initialize a new JSON object.");
+        return AC_E_MEMORY_ALLOCATION;
+    }
+    int r;
+    if ((r = json_add(obj, "id", json_object_new_int(req->id)))) {
+        goto fail;
+    }
+    switch (req->type) {
+        case AC_REQUEST_CMD: {
+            if ((r = json_add(obj, "type", json_object_new_string("cmd")))) {
+                goto fail;
+            }
+            ac_request_cmd_t *cmd = (ac_request_cmd_t *) req;
+            if ((r = json_add(obj, "cmd", json_object_new_string(cmd->cmd)))) {
+                goto fail;
+            }
+            if (cmd->config) {
+                json_object *c;
+                if (!(c = json_object_new_object())) {
+                    LOGE("Cannot initialize a new JSON object.");
+                    goto fail;
+                }
+                if ((r = serialize_config(cmd->config, c))) {
+                    json_object_put(c);
+                    goto fail;
+                }
+                if ((r = json_add(obj, "config", c))) {
+                    goto fail;
+                }
+            }
+            break;
+        }
+        case AC_REQUEST_SET_CONFIG: {
+            if ((r = json_add(obj, "set_config", json_object_new_string("cmd")))) {
+                goto fail;
+            }
+            ac_request_set_config_t *set_config = (ac_request_set_config_t *) req;
+            json_object *c;
+            if (!(c = json_object_new_object())) {
+                LOGE("Cannot initialize a new JSON object.");
+                goto fail;
+            }
+            if ((r = serialize_config(&set_config->config, c))) {
+                json_object_put(c);
+                goto fail;
+            }
+            if ((r = json_add(obj, "config", c))) {
+                goto fail;
+            }
+            break;
+        }
+        default: {
+            LOGE("Invalid request supplied.");
+            r = AC_E_INVALID_REQUEST;
+            goto fail;
+        }
+    }
+    *out = obj;
+    return AC_E_OK;
+    fail:
+    {
+        if (obj) {
+            json_object_put(obj);
+        }
+        return r;
+    }
+}
+
+int serializer_finalize(void) {
+    AC_CHECK_INIT;
+    json_tokener_reset(config->tok);
+}
diff --git a/client/libacron/private/serializer.h b/client/libacron/private/serializer.h
new file mode 100644
index 0000000..1b9a38b
--- /dev/null
+++ b/client/libacron/private/serializer.h
@@ -0,0 +1,18 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+
+#ifndef LIBAC_SERIALIZER_H
+#define LIBAC_SERIALIZER_H
+
+/* An internal error code indicating that more data is required.
+ * Should not conflict with other error codes. */
+#define AC_E_SERIALIZER_CONTINUE    -1
+
+int deserialize(const char *string, unsigned int len, ac_obj_t **out);
+
+int serializer_finalize(void);
+
+int serialize_request(const ac_request_t *req, json_object **out);
+
+#endif /* LIBAC_SERIALIZER_H */
diff --git a/client/libacron/requests.c b/client/libacron/requests.c
new file mode 100644
index 0000000..c71d6c2
--- /dev/null
+++ b/client/libacron/requests.c
@@ -0,0 +1,5 @@
+/*
+ * Created by yuuta on 7/19/22.
+ */
+#include "requests.h"
+
diff --git a/client/libacron/wic b/client/libacron/wic
new file mode 160000
+Subproject 54d124005c25ca376aa4e85c45f87b6c3bb9579