From a6b6a4179c4510042e8b7ce235cab97c40d1c536 Mon Sep 17 00:00:00 2001
From: Eric Mertens <emertens@galois.com>
Date: Wed, 22 Nov 2023 19:59:34 -0800
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=A3?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .gitignore        |   6 +
 CMakeLists.txt    |  24 ++++
 CMakePresets.json |  24 ++++
 connection.cpp    | 108 +++++++++++++++++
 connection.hpp    |  97 +++++++++++++++
 irc_thread.hpp    |  27 +++++
 ircmsg.cpp        | 149 +++++++++++++++++++++++
 ircmsg.hpp        |  62 ++++++++++
 linebuffer.hpp    |  97 +++++++++++++++
 main.cpp          | 302 ++++++++++++++++++++++++++++++++++++++++++++++
 settings.cpp      |  17 +++
 settings.hpp      |  17 +++
 12 files changed, 930 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 CMakeLists.txt
 create mode 100644 CMakePresets.json
 create mode 100644 connection.cpp
 create mode 100644 connection.hpp
 create mode 100644 irc_thread.hpp
 create mode 100644 ircmsg.cpp
 create mode 100644 ircmsg.hpp
 create mode 100644 linebuffer.hpp
 create mode 100644 main.cpp
 create mode 100644 settings.cpp
 create mode 100644 settings.hpp

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f58b540
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+/out
+/config.toml
+/.ccls
+/archive
+/.vscode
+/compile_commands.json
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..19ffbf7
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,24 @@
+cmake_minimum_required(VERSION 3.13)
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 20)
+project(xbot
+    VERSION 1
+    LANGUAGES C CXX
+)
+
+find_package(PkgConfig REQUIRED)
+
+pkg_check_modules(LIBIDN IMPORTED_TARGET libidn)
+find_package(Boost REQUIRED)
+find_package(OpenSSL REQUIRED)
+
+include(FetchContent)
+FetchContent_Declare(
+    tomlplusplus
+    GIT_REPOSITORY https://github.com/marzer/tomlplusplus.git
+    GIT_TAG        v3.4.0
+)
+FetchContent_MakeAvailable(tomlplusplus)
+
+add_executable(xbot main.cpp ircmsg.cpp settings.cpp connection.cpp)
+target_link_libraries(xbot PRIVATE Boost::headers OpenSSL::SSL tomlplusplus_tomlplusplus)
diff --git a/CMakePresets.json b/CMakePresets.json
new file mode 100644
index 0000000..49b13c6
--- /dev/null
+++ b/CMakePresets.json
@@ -0,0 +1,24 @@
+{
+    "version": 2,
+    "configurePresets": [
+        {
+            "name": "arm-mac",
+            "displayName": "Configure preset using toolchain file",
+            "description": "Sets Ninja generator, build and install directory",
+            "generator": "Ninja",
+            "binaryDir": "${sourceDir}/out/build/${presetName}",
+            "cacheVariables": {
+                "CMAKE_BUILD_TYPE": "Debug",
+                "CMAKE_TOOLCHAIN_FILE": "",
+                "CMAKE_INSTALL_PREFIX": "${sourceDir}/out/install/${presetName}",
+                "CMAKE_EXPORT_COMPILE_COMMANDS": "On"
+            }
+        }
+    ],
+    "buildPresets": [
+        {
+            "name": "arm-mac",
+            "configurePreset": "arm-mac"
+        }
+    ]
+}
diff --git a/connection.cpp b/connection.cpp
new file mode 100644
index 0000000..817718b
--- /dev/null
+++ b/connection.cpp
@@ -0,0 +1,108 @@
+#include "connection.hpp"
+
+auto Connection::writer_() -> void
+{
+    std::vector<boost::asio::const_buffer> buffers;
+    buffers.reserve(write_strings_.size());
+    for (auto const& elt : write_strings_)
+    {
+        buffers.push_back(boost::asio::buffer(elt));
+    }
+    boost::asio::async_write(
+        stream_,
+        buffers,
+        [weak = weak_from_this()
+        ,strings = std::move(write_strings_)
+        ](boost::system::error_code const& error, std::size_t)
+        {
+            if (not error)
+            {
+                if (auto self = weak.lock())
+                {
+                    self->writer();
+                }
+            }
+        });
+    write_strings_.clear();
+}
+
+auto Connection::writer() -> void
+{
+    if (write_strings_.empty())
+    {
+        write_timer_.async_wait([weak = weak_from_this()](auto){
+            if (auto self = weak.lock())
+            {
+                if (not self->write_strings_.empty())
+                {
+                    self->writer_();
+                }
+            }
+        });
+    }
+    else
+    {
+        writer_();
+    }
+}
+
+auto Connection::connect(
+    boost::asio::io_context & io,
+    Settings settings)
+-> boost::asio::awaitable<void>
+{
+    auto self = shared_from_this();
+
+    {
+        auto resolver = boost::asio::ip::tcp::resolver{io};
+        auto const endpoints = co_await resolver.async_resolve(settings.host, settings.service, boost::asio::use_awaitable);
+        auto const endpoint = co_await boost::asio::async_connect(stream_, endpoints, boost::asio::use_awaitable);
+
+        self->writer();
+        dispatch(&IrcThread::on_connect);
+    }
+
+    for(LineBuffer buffer{32'768};;)
+    {
+        boost::system::error_code error;
+        auto const n = co_await stream_.async_read_some(buffer.get_buffer(), boost::asio::redirect_error(boost::asio::use_awaitable, error));
+        if (error)
+        {
+            break;
+        }
+        buffer.add_bytes(n, [this](char * line) {
+            dispatch<ircmsg const&>(&IrcThread::on_msg, parse_irc_message(line));
+        });
+    }
+
+    dispatch(&IrcThread::on_disconnect);
+}
+
+auto Connection::write(std::string message) -> void
+{
+    auto const need_cancel = write_strings_.empty();
+
+    message += "\r\n";
+    write_strings_.push_back(std::move(message));
+
+    if (need_cancel)
+    {
+        write_timer_.cancel_one();
+    }
+}
+
+auto Connection::write(std::string front, std::string_view last) -> void
+    {
+        auto const is_invalid = [](char x) -> bool {
+            return x == '\0' || x == '\r' || x == '\n';
+        };
+
+        if (last.end() != std::find_if(last.begin(), last.end(), is_invalid))
+        {
+            throw std::runtime_error{"bad irc argument"};
+        }
+
+        front += " :";
+        front += last;
+        write(std::move(front));
+    }
diff --git a/connection.hpp b/connection.hpp
new file mode 100644
index 0000000..cbc325e
--- /dev/null
+++ b/connection.hpp
@@ -0,0 +1,97 @@
+#pragma once
+
+#include "irc_thread.hpp"
+#include "ircmsg.hpp"
+#include "linebuffer.hpp"
+#include "settings.hpp"
+
+#include <boost/asio.hpp>
+
+#include <chrono>
+#include <coroutine>
+#include <iostream>
+#include <list>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <utility>
+#include <variant>
+#include <vector>
+
+class Connection : public std::enable_shared_from_this<Connection>
+{
+    boost::asio::ip::tcp::socket stream_;
+    boost::asio::steady_timer write_timer_;
+
+    std::list<std::string> write_strings_;
+    std::vector<std::unique_ptr<IrcThread>> threads_;
+
+    auto writer() -> void;
+    auto writer_() -> void;
+
+    template <typename... Args>
+    auto dispatch(
+        IrcThread::callback_result (IrcThread::* method)(Args...),
+        Args... args
+    ) -> void
+    {
+        std::vector<std::unique_ptr<IrcThread>> work;
+        work.swap(threads_);
+        std::sort(work.begin(), work.end(), [](auto const& a, auto const& b) { return a->priority() < b->priority(); });
+
+        std::size_t const n = work.size();
+        for (std::size_t i = 0; i < n; i++)
+        {
+            auto const [thread_outcome, msg_outcome] = (work[i].get()->*method)(args...);
+            if (thread_outcome == ThreadOutcome::Continue)
+            {
+                threads_.push_back(std::move(work[i]));
+            }
+            if (msg_outcome == EventOutcome::Consume)
+            {
+                std::move(work.begin() + i + 1, work.end(), std::back_inserter(threads_));
+                break;
+            }
+        }
+    }
+
+public:
+    Connection(boost::asio::io_context & io)
+    : stream_{io}
+    , write_timer_{io, std::chrono::steady_clock::time_point::max()}
+    {
+    }
+
+    auto listen(std::unique_ptr<IrcThread> thread) -> void
+    {
+        threads_.push_back(std::move(thread));
+    }
+
+    auto write(std::string front, std::string_view last) -> void;
+
+    template <typename... Args>
+    auto write(std::string front, std::string_view next, Args ...rest) -> void
+    {
+        auto const is_invalid = [](char x) -> bool {
+            return x == '\0' || x == '\r' || x == '\n' || x == ' ';
+        };
+
+        if (next.empty() || next.end() != std::find_if(next.begin(), next.end(), is_invalid))
+        {
+            throw std::runtime_error{"bad irc argument"};
+        }
+
+        front += " ";
+        front += next;
+        write(std::move(front), rest...);
+    }
+
+    auto write(std::string message) -> void;
+
+    auto connect(
+        boost::asio::io_context & io,
+        Settings settings
+    ) -> boost::asio::awaitable<void>;
+};
+
diff --git a/irc_thread.hpp b/irc_thread.hpp
new file mode 100644
index 0000000..7da32f5
--- /dev/null
+++ b/irc_thread.hpp
@@ -0,0 +1,27 @@
+#pragma once
+
+#include "ircmsg.hpp"
+
+enum class EventOutcome
+{
+    Pass,
+    Consume,
+};
+
+enum class ThreadOutcome
+{
+    Continue,
+    Finish,
+};
+
+struct IrcThread
+{
+    using priority_type = std::uint64_t;
+    using callback_result = std::pair<ThreadOutcome, EventOutcome>;
+    virtual ~IrcThread() {}
+
+    virtual auto on_connect() -> callback_result { return {}; }
+    virtual auto on_disconnect() -> callback_result { return {}; };
+    virtual auto on_msg(ircmsg const&) -> callback_result { return {}; };
+    virtual auto priority() const -> priority_type = 0;
+};
diff --git a/ircmsg.cpp b/ircmsg.cpp
new file mode 100644
index 0000000..fa3542f
--- /dev/null
+++ b/ircmsg.cpp
@@ -0,0 +1,149 @@
+#include <cstring>
+#include <optional>
+
+#include "ircmsg.hpp"
+
+namespace {
+class parser {
+    char* msg_;
+    inline static char empty[1];
+
+    inline void trim() {
+        while (*msg_ == ' ') msg_++;
+    }
+
+public:
+    parser(char* msg) : msg_(msg) {
+        if (msg_ == nullptr) {
+            msg_ = empty;
+        } else {
+            trim();
+        }
+    }
+
+    char* word() {
+        auto const start = msg_;
+        while (*msg_ != '\0' && *msg_ != ' ') msg_++;
+        if (*msg_ != '\0') { // prepare for next token
+            *msg_++ = '\0';
+            trim();
+        }
+        return start;
+    }
+
+    bool match(char c) {
+        if (c == *msg_) {
+            msg_++;
+            return true;
+        }
+        return false;
+    }
+
+    bool isempty() const {
+        return *msg_ == '\0';
+    }
+
+    char const* peek() {
+        return msg_;
+    }
+};
+
+std::string_view unescape_tag_value(char* const val)
+{
+    // only start copying at the first escape character
+    // skip everything before that
+    auto cursor = strchr(val, '\\');
+    if (cursor == nullptr) { return {val}; }
+
+    auto write = cursor;
+    for (; *cursor; cursor++)
+    {
+        if (*cursor == '\\')
+        {
+            cursor++;
+            switch (*cursor)
+            {
+                default  : *write++ = *cursor; break;
+                case ':' : *write++ = ';'    ; break;
+                case 's' : *write++ = ' '    ; break;
+                case 'r' : *write++ = '\r'   ; break;
+                case 'n' : *write++ = '\n'   ; break;
+                case '\0': return {val, write};
+            }
+        }
+        else
+        {
+            *write++ = *cursor;
+        }
+    }
+    return {val, write};
+}
+
+} // namespace
+
+auto parse_irc_tags(char* str) -> std::vector<irctag>
+{
+    std::vector<irctag> tags;
+
+    do {
+        auto val = strsep(&str, ";");
+        auto key = strsep(&val, "=");
+        if ('\0' == *key) {
+            throw irc_parse_error(irc_error_code::MISSING_TAG);
+        }
+        if (nullptr == val) {
+            tags.emplace_back(key, "");
+        } else {
+            tags.emplace_back(std::string_view{key, val-1}, unescape_tag_value(val));
+        }
+    } while(nullptr != str);
+
+    return tags;
+}
+
+auto parse_irc_message(char* msg) -> ircmsg
+{
+    parser p {msg};
+    ircmsg out;
+
+    /* MESSAGE TAGS */
+    if (p.match('@')) {
+        out.tags = parse_irc_tags(p.word());
+    }
+
+    /* MESSAGE SOURCE */
+    if (p.match(':')) {
+        out.source = p.word();
+    }
+
+    /* MESSAGE COMMANDS */
+    out.command = p.word();
+    if (out.command.empty()) {
+        throw irc_parse_error{irc_error_code::MISSING_COMMAND};
+    }
+
+    /* MESSAGE ARGUMENTS */
+    while (!p.isempty()) {
+        if (p.match(':')) {
+            out.args.push_back(p.peek());
+            break;
+        }
+        out.args.push_back(p.word());
+    }
+
+    return out;
+}
+
+auto ircmsg::hassource() const -> bool
+{
+    return source.data() != nullptr;
+}
+
+auto operator<<(std::ostream& out, irc_error_code code) -> std::ostream&
+{
+    switch(code) {
+        case irc_error_code::MISSING_COMMAND: out << "MISSING COMMAND"; return out;
+        case irc_error_code::MISSING_TAG: out << "MISSING TAG"; return out;
+        default: return out;
+    }
+}
diff --git a/ircmsg.hpp b/ircmsg.hpp
new file mode 100644
index 0000000..e50b385
--- /dev/null
+++ b/ircmsg.hpp
@@ -0,0 +1,62 @@
+#pragma once
+
+#include <iostream>
+#include <string_view>
+#include <vector>
+
+struct irctag
+{
+    std::string_view key;
+    std::string_view val;
+
+    irctag(std::string_view key, std::string_view val) : key{key}, val{val} {}
+
+    friend auto operator==(irctag const&, irctag const&) -> bool = default;
+};
+
+struct ircmsg
+{
+    std::vector<irctag> tags;
+    std::vector<std::string_view> args;
+    std::string_view source;
+    std::string_view command;
+
+    ircmsg() = default;
+
+    ircmsg(
+        std::vector<irctag> && tags,
+        std::string_view source,
+        std::string_view command,
+        std::vector<std::string_view> && args)
+    : tags(std::move(tags)),
+      args(std::move(args)),
+      source{source},
+      command{command} {}
+
+      bool hassource() const;
+
+      friend bool operator==(ircmsg const&, ircmsg const&) = default;
+};
+
+enum class irc_error_code {
+    MISSING_TAG,
+    MISSING_COMMAND,
+};
+
+auto operator<<(std::ostream& out, irc_error_code) -> std::ostream&;
+
+struct irc_parse_error : public std::exception {
+    irc_error_code code;
+    irc_parse_error(irc_error_code code) : code(code) {}
+};
+
+/**
+ * Parses the given IRC message into a structured format.
+ * The original message is mangled to store string fragments
+ * that are pointed to by the structured message type.
+ *
+ * Returns zero for success, non-zero for parse error.
+ */
+auto parse_irc_message(char* msg) -> ircmsg;
+
+auto parse_irc_tags(char* msg) -> std::vector<irctag>;
diff --git a/linebuffer.hpp b/linebuffer.hpp
new file mode 100644
index 0000000..a832ec0
--- /dev/null
+++ b/linebuffer.hpp
@@ -0,0 +1,97 @@
+#pragma once
+/**
+ * @file linebuffer.hpp
+ * @author Eric Mertens <emertens@gmail.com>
+ * @brief A line buffering class
+ * @version 0.1
+ * @date 2023-08-22
+ *
+ * @copyright Copyright (c) 2023
+ *
+ */
+
+#include <boost/asio/buffer.hpp>
+
+#include <algorithm>
+#include <concepts>
+#include <vector>
+
+/**
+ * @brief Fixed-size buffer with line-oriented dispatch
+ *
+ */
+class LineBuffer
+{
+    std::vector<char> buffer;
+
+    // [buffer.begin(), end_) contains buffered data
+    // [end_, buffer.end()) is available buffer space
+    std::vector<char>::iterator end_;
+
+public:
+    /**
+     * @brief Construct a new Line Buffer object
+     *
+     * @param n Buffer size
+     */
+    LineBuffer(std::size_t n) : buffer(n), end_{buffer.begin()} {}
+
+    /**
+     * @brief Get the available buffer space
+     *
+     * @return boost::asio::mutable_buffer
+     */
+    auto get_buffer() -> boost::asio::mutable_buffer
+    {
+        return boost::asio::buffer(&*end_, std::distance(end_, buffer.end()));
+    }
+
+    /**
+     * @brief Commit new buffer bytes and dispatch line callback
+     *
+     * The first n bytes of the buffer will be considered to be
+     * populated. The line callback function will be called once
+     * per completed line. Those lines are removed from the buffer
+     * and the is ready for additional calls to get_buffer and
+     * add_bytes.
+     *
+     * @param n Bytes written to the last call of get_buffer
+     * @param line_cb Callback function to run on each completed line
+     */
+    auto add_bytes(std::size_t n, std::invocable<char *> auto line_cb) -> void
+    {
+        auto const start = end_;
+        std::advance(end_, n);
+
+        // new data is now located in [start, end_)
+
+        // cursor marks the beginning of the current line
+        auto cursor = buffer.begin();
+
+        for (auto nl = std::find(start, end_, '\n');
+             nl != end_;
+             nl = std::find(cursor, end_, '\n'))
+        {
+            // Null-terminate the line. Support both \n and \r\n
+            if (cursor < nl && *std::prev(nl) == '\r')
+            {
+                *std::prev(nl) = '\0';
+            }
+            else
+            {
+                *nl = '\0';
+            }
+
+            line_cb(&*cursor);
+
+            cursor = std::next(nl);
+        }
+
+        // If any lines were processed, move all processed lines to
+        // the front of the buffer
+        if (cursor != buffer.begin())
+        {
+            end_ = std::move(cursor, end_, buffer.begin());
+        }
+    }
+};
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..3c39a7b
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,302 @@
+#include <boost/asio.hpp>
+#include <boost/asio/ssl.hpp>
+
+#include "linebuffer.hpp"
+#include "ircmsg.hpp"
+#include "settings.hpp"
+#include "irc_thread.hpp"
+#include "connection.hpp"
+
+#include <algorithm>
+#include <chrono>
+#include <fstream>
+#include <coroutine>
+#include <iostream>
+#include <limits>
+#include <list>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <utility>
+#include <variant>
+#include <vector>
+#include <unordered_map>
+#include <unordered_set>
+
+using namespace std::chrono_literals;
+
+
+struct ChatThread : public IrcThread
+{
+    auto priority() const -> priority_type override
+    {
+        return 100;
+    }
+    auto on_msg(ircmsg const& irc) -> std::pair<ThreadOutcome, EventOutcome> override
+    {
+        if (irc.command == "PRIVMSG" && 2 == irc.args.size())
+        {
+            std::cout << "Chat from " << irc.source << ": " << irc.args[1] << std::endl;
+            return {ThreadOutcome::Continue, EventOutcome::Pass};
+        }
+        else
+        {
+            return {ThreadOutcome::Continue, EventOutcome::Pass};
+        }
+    }
+};
+
+struct UnhandledThread : public IrcThread
+{
+    auto priority() const -> priority_type override
+    {
+        return std::numeric_limits<IrcThread::priority_type>::max();
+    }
+
+    auto on_msg(ircmsg const& irc) -> std::pair<ThreadOutcome, EventOutcome> override
+    {
+        std::cout << "Unhandled message " << irc.command;
+        for (auto const arg : irc.args)
+        {
+            std::cout << " " << arg;
+        }
+        std::cout << "\n";
+        return {ThreadOutcome::Continue, EventOutcome::Pass};
+    }
+};
+
+class PingThread : public IrcThread
+{
+    Connection * connection_;
+
+public:
+    PingThread(Connection * connection) noexcept : connection_{connection} {}
+
+    auto priority() const -> priority_type override
+    {
+        return 0;
+    }
+
+    auto on_msg(ircmsg const& irc) -> std::pair<ThreadOutcome, EventOutcome> override
+    {
+        if (irc.command == "PING" && 1 == irc.args.size())
+        {
+            connection_->write("PONG", irc.args[0]);
+            return {ThreadOutcome::Continue, EventOutcome::Consume};
+        }
+        else
+        {
+            return {};
+        }
+    }
+};
+
+struct RegistrationThread : IrcThread
+{
+    Connection * connection_;
+    std::string password_;
+    std::string username_;
+    std::string realname_;
+    std::string nickname_;
+
+    std::unordered_map<std::string, std::string> caps;
+    std::unordered_set<std::string> outstanding;
+
+    enum class Stage
+    {
+        LsReply,
+        AckReply,
+    };
+
+    Stage stage_;
+
+    RegistrationThread(
+        Connection * connection_,
+        std::string password,
+        std::string username,
+        std::string realname,
+        std::string nickname
+    )
+    : connection_{connection_}
+    , password_{password}
+    , username_{username}
+    , realname_{realname}
+    , nickname_{nickname}
+    , stage_{Stage::LsReply}
+    {}
+
+    auto priority() const -> priority_type override { return 1; }
+    auto on_connect() -> IrcThread::callback_result override
+    {
+        connection_->write("CAP", "LS", "302");
+        connection_->write("PASS", password_);
+        connection_->write("USER", username_, "*", "*", realname_);
+        connection_->write("NICK", nickname_);
+        return {};
+    }
+
+    auto send_req() -> IrcThread::callback_result
+    {
+        std::string request;
+        char const* want[] = { "extended-join", "account-notify", "draft/chathistory", "batch", "soju.im/no-implicit-names", "chghost", "setname", "account-tag", "solanum.chat/oper", "solanum.chat/identify-msg", "solanum.chat/realhost", "server-time", "invite-notify", "extended-join" };
+        for (auto cap : want)
+        {
+            if (caps.contains(cap))
+            {
+                request.append(cap);
+                request.push_back(' ');
+                outstanding.insert(cap);
+            }
+        }
+        if (not outstanding.empty())
+        {
+            request.pop_back();
+            connection_->write("CAP", "REQ", request);
+            stage_ = Stage::AckReply;
+            return {ThreadOutcome::Continue, EventOutcome::Consume};
+        }
+        else
+        {
+            connection_->write("CAP", "END");
+            return {ThreadOutcome::Finish, EventOutcome::Consume};
+        }
+    }
+
+    auto capack(ircmsg const& msg) -> IrcThread::callback_result
+    {
+        auto const n = msg.args.size();
+        if ("CAP" == msg.command && n >= 2 && "*" == msg.args[0] && "ACK" == msg.args[1])
+        {
+            auto in = std::istringstream{std::string{msg.args[2]}};
+            std::for_each(
+                std::istream_iterator<std::string>{in},
+                std::istream_iterator<std::string>{},
+                [this](std::string x) {
+                    outstanding.erase(x);
+                }
+            );
+            if (outstanding.empty())
+            {
+                connection_->write("CAP","END");
+                return {ThreadOutcome::Finish, EventOutcome::Consume};
+            }
+            else
+            {
+                return {ThreadOutcome::Continue, EventOutcome::Consume};
+            }
+        }
+        else
+        {
+            return {};
+        }
+    }
+
+    auto capls(ircmsg const& msg) -> IrcThread::callback_result
+    {
+        auto const n = msg.args.size();
+        if ("CAP" == msg.command && n >= 2 && "*" == msg.args[0] && "LS" == msg.args[1])
+        {
+            std::string_view const* kvs;
+            bool last;
+
+            if (3 == n)
+            {
+                kvs = &msg.args[2];
+                last = true;
+            }
+            else if (4 == n && "*" == msg.args[2])
+            {
+                kvs = &msg.args[3];
+                last = false;
+            }
+            else
+            {
+                return {};
+            }
+
+            auto in = std::istringstream{std::string{*kvs}};
+
+            std::for_each(
+                std::istream_iterator<std::string>{in},
+                std::istream_iterator<std::string>{},
+                [this](std::string x) {
+                    auto const eq = x.find('=');
+                    if (eq == x.npos)
+                    {
+                        caps.emplace(x, std::string{});
+                    }
+                    else
+                    {
+                        caps.emplace(std::string{x, 0, eq}, std::string{x, eq+1, x.npos});
+                    }
+                }
+            );
+
+            if (last)
+            {
+                return send_req();
+            }
+
+            return {ThreadOutcome::Continue, EventOutcome::Consume};
+        }
+        else
+        {
+            return {};
+        }
+
+    }
+
+    auto on_msg(ircmsg const& msg) -> IrcThread::callback_result override
+    {
+        switch (stage_)
+        {
+            case Stage::LsReply: return capls(msg);
+            case Stage::AckReply: return capack(msg);
+            default: return {};
+        }
+    }
+};
+
+auto start(boost::asio::io_context & io, Settings const& settings) -> void
+{
+    auto connection = std::make_shared<Connection>(io);
+
+    connection->listen(std::make_unique<PingThread>(connection.get()));
+    connection->listen(std::make_unique<RegistrationThread>(connection.get(), settings.password, settings.username, settings.realname, settings.nickname));
+    connection->listen(std::make_unique<ChatThread>());
+    connection->listen(std::make_unique<UnhandledThread>());
+
+    boost::asio::co_spawn(
+        io,
+        connection->connect(io, settings),
+        [&io, &settings](std::exception_ptr e)
+        {
+            auto timer = boost::asio::steady_timer{io};
+            timer.expires_from_now(5s);
+            timer.async_wait([&io, &settings](auto) {
+                start(io, settings);
+            });
+        });
+}
+
+auto get_settings() -> Settings
+{
+    if (auto config_stream = std::ifstream {"config.toml"})
+    {
+        return Settings::from_stream(config_stream);
+    }
+    else
+    {
+        std::cerr << "Unable to open config.toml\n";
+        std::exit(1);
+    }
+}
+
+auto main() -> int
+{
+    auto const settings = get_settings();
+    auto io = boost::asio::io_context{};
+    start(io, settings);
+    io.run();
+}
diff --git a/settings.cpp b/settings.cpp
new file mode 100644
index 0000000..20e1a6c
--- /dev/null
+++ b/settings.cpp
@@ -0,0 +1,17 @@
+#include "settings.hpp"
+
+#define TOML_ENABLE_FORMATTERS 0
+#include <toml++/toml.hpp>
+
+auto Settings::from_stream(std::istream & in) -> Settings
+{
+    auto const config = toml::parse(in);
+    return Settings{
+        .host     = config["host"].value_or(std::string{"*"}),
+        .service  = config["service"].value_or(std::string{"*"}),
+        .password = config["password"].value_or(std::string{"*"}),
+        .username = config["username"].value_or(std::string{"*"}),
+        .realname = config["realname"].value_or(std::string{"*"}),
+        .nickname = config["nickname"].value_or(std::string{"*"})
+    };
+}
diff --git a/settings.hpp b/settings.hpp
new file mode 100644
index 0000000..8cba813
--- /dev/null
+++ b/settings.hpp
@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+#include <iostream>
+
+struct Settings
+{
+    std::string host;
+    std::string service;
+    std::string password;
+    std::string username;
+    std::string realname;
+    std::string nickname;
+
+    static auto from_stream(std::istream & in) -> Settings;
+};
+