LibGemini: Implement basic Gemini protocol support

Author: https://github.com/deoxxa
Commit: https://github.com/SerenityOS/serenity/commit/308a755c38a
Pull-request: https://github.com/SerenityOS/serenity/pull/2218
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/bugaevc

Libraries/CMakeLists.txt

@@ -4,6 +4,7 @@ add_subdirectory(LibCore)
 add_subdirectory(LibCrypto)
 add_subdirectory(LibDebug)
 add_subdirectory(LibDesktop)
+add_subdirectory(LibGemini)
 add_subdirectory(LibGfx)
 add_subdirectory(LibGUI)
 add_subdirectory(LibHTTP)

Libraries/LibGemini/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(SOURCES
+    GeminiJob.cpp
+    GeminiRequest.cpp
+    GeminiResponse.cpp
+    Job.cpp
+)
+
+serenity_lib(LibGemini gemini)
+target_link_libraries(LibGemini LibCore LibTLS)

Libraries/LibGemini/Forward.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+namespace Gemini {
+
+class GeminiRequest;
+class GeminiResponse;
+class GeminiJob;
+class Job;
+
+}

Libraries/LibGemini/GeminiJob.cpp

@@ -0,0 +1,136 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibCore/EventLoop.h>
+#include <LibGemini/GeminiJob.h>
+#include <LibGemini/GeminiResponse.h>
+#include <LibTLS/TLSv12.h>
+#include <stdio.h>
+#include <unistd.h>
+
+//#define GEMINIJOB_DEBUG
+
+namespace Gemini {
+
+void GeminiJob::start()
+{
+    ASSERT(!m_socket);
+    m_socket = TLS::TLSv12::construct(this);
+    m_socket->on_tls_connected = [this] {
+#ifdef GEMINIJOB_DEBUG
+        dbg() << "GeminiJob: on_connected callback";
+#endif
+        on_socket_connected();
+    };
+    m_socket->on_tls_error = [this](TLS::AlertDescription error) {
+        if (error == TLS::AlertDescription::HandshakeFailure) {
+            deferred_invoke([this](auto&) {
+                return did_fail(Core::NetworkJob::Error::ProtocolFailed);
+            });
+        } else if (error == TLS::AlertDescription::DecryptError) {
+            deferred_invoke([this](auto&) {
+                return did_fail(Core::NetworkJob::Error::ConnectionFailed);
+            });
+        } else {
+            deferred_invoke([this](auto&) {
+                return did_fail(Core::NetworkJob::Error::TransmissionFailed);
+            });
+        }
+    };
+    m_socket->on_tls_finished = [this] {
+        finish_up();
+    };
+    bool success = ((TLS::TLSv12&)*m_socket).connect(m_request.url().host(), m_request.url().port());
+    if (!success) {
+        deferred_invoke([this](auto&) {
+            return did_fail(Core::NetworkJob::Error::ConnectionFailed);
+        });
+    }
+}
+
+void GeminiJob::shutdown()
+{
+    if (!m_socket)
+        return;
+    m_socket->on_tls_ready_to_read = nullptr;
+    m_socket->on_tls_connected = nullptr;
+    remove_child(*m_socket);
+    m_socket = nullptr;
+}
+
+void GeminiJob::read_while_data_available(Function<IterationDecision()> read)
+{
+    while (m_socket->can_read()) {
+        if (read() == IterationDecision::Break)
+            break;
+    }
+}
+
+void GeminiJob::register_on_ready_to_read(Function<void()> callback)
+{
+    m_socket->on_tls_ready_to_read = [callback = move(callback)](auto&) {
+        callback();
+    };
+}
+
+void GeminiJob::register_on_ready_to_write(Function<void()> callback)
+{
+    m_socket->on_tls_ready_to_write = [callback = move(callback)](auto&) {
+        callback();
+    };
+}
+
+bool GeminiJob::can_read_line() const
+{
+    return m_socket->can_read_line();
+}
+
+ByteBuffer GeminiJob::read_line(size_t size)
+{
+    return m_socket->read_line(size);
+}
+
+ByteBuffer GeminiJob::receive(size_t size)
+{
+    return m_socket->read(size);
+}
+
+bool GeminiJob::can_read() const
+{
+    return m_socket->can_read();
+}
+
+bool GeminiJob::eof() const
+{
+    return m_socket->eof();
+}
+
+bool GeminiJob::write(const ByteBuffer& data)
+{
+    return m_socket->write(data);
+}
+
+}

Libraries/LibGemini/GeminiJob.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibCore/NetworkJob.h>
+#include <LibGemini/GeminiRequest.h>
+#include <LibGemini/GeminiResponse.h>
+#include <LibGemini/Job.h>
+#include <LibTLS/TLSv12.h>
+
+namespace Gemini {
+
+class GeminiJob final : public Job {
+    C_OBJECT(GeminiJob)
+public:
+    explicit GeminiJob(const GeminiRequest& request)
+        : Job(request)
+    {
+    }
+
+    virtual ~GeminiJob() override
+    {
+    }
+
+    virtual void start() override;
+    virtual void shutdown() override;
+
+protected:
+    virtual void register_on_ready_to_read(Function<void()>) override;
+    virtual void register_on_ready_to_write(Function<void()>) override;
+    virtual bool can_read_line() const override;
+    virtual ByteBuffer read_line(size_t) override;
+    virtual bool can_read() const override;
+    virtual ByteBuffer receive(size_t) override;
+    virtual bool eof() const override;
+    virtual bool write(const ByteBuffer&) override;
+    virtual bool is_established() const override { return m_socket->is_established(); }
+    virtual bool should_fail_on_empty_payload() const override { return false; }
+    virtual void read_while_data_available(Function<IterationDecision()>) override;
+
+private:
+    RefPtr<TLS::TLSv12> m_socket;
+    bool m_queued_finish { false };
+};
+
+}

Libraries/LibGemini/GeminiRequest.cpp

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StringBuilder.h>
+#include <AK/URL.h>
+#include <LibGemini/GeminiJob.h>
+#include <LibGemini/GeminiRequest.h>
+
+namespace Gemini {
+
+GeminiRequest::GeminiRequest()
+{
+}
+
+GeminiRequest::~GeminiRequest()
+{
+}
+
+RefPtr<Core::NetworkJob> GeminiRequest::schedule()
+{
+    auto job = GeminiJob::construct(*this);
+    job->start();
+    return job;
+}
+
+ByteBuffer GeminiRequest::to_raw_request() const
+{
+    StringBuilder builder;
+    builder.append(m_url.to_string());
+    builder.append("\r\n");
+    return builder.to_byte_buffer();
+}
+
+Optional<GeminiRequest> GeminiRequest::from_raw_request(const ByteBuffer& raw_request)
+{
+    URL url = StringView(raw_request);
+    if (!url.is_valid())
+        return {};
+    GeminiRequest request;
+    request.m_url = url;
+    return request;
+}
+
+}

Libraries/LibGemini/GeminiRequest.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Optional.h>
+#include <AK/String.h>
+#include <AK/URL.h>
+#include <LibCore/Forward.h>
+
+namespace Gemini {
+
+class GeminiRequest {
+public:
+    GeminiRequest();
+    ~GeminiRequest();
+
+    const URL& url() const { return m_url; }
+    void set_url(const URL& url) { m_url = url; }
+
+    ByteBuffer to_raw_request() const;
+
+    RefPtr<Core::NetworkJob> schedule();
+
+    static Optional<GeminiRequest> from_raw_request(const ByteBuffer&);
+
+private:
+    URL m_url;
+};
+
+}

Libraries/LibGemini/GeminiResponse.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibGemini/GeminiResponse.h>
+
+namespace Gemini {
+
+GeminiResponse::GeminiResponse(int status, String meta, ByteBuffer&& payload)
+    : Core::NetworkResponse(move(payload))
+    , m_status(status)
+    , m_meta(meta)
+{
+}
+
+GeminiResponse::~GeminiResponse()
+{
+}
+
+}

Libraries/LibGemini/GeminiResponse.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <LibCore/NetworkResponse.h>
+
+namespace Gemini {
+
+class GeminiResponse : public Core::NetworkResponse {
+public:
+    virtual ~GeminiResponse() override;
+    static NonnullRefPtr<GeminiResponse> create(int status, String meta, ByteBuffer&& payload)
+    {
+        return adopt(*new GeminiResponse(status, meta, move(payload)));
+    }
+
+    int status() const { return m_status; }
+    String meta() const { return m_meta; }
+
+private:
+    GeminiResponse(int status, String, ByteBuffer&&);
+
+    int m_status { 0 };
+    String m_meta;
+};
+
+}

Libraries/LibGemini/Job.cpp

@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibGemini/GeminiResponse.h>
+#include <LibGemini/Job.h>
+#include <stdio.h>
+#include <unistd.h>
+
+//#define JOB_DEBUG
+
+namespace Gemini {
+
+Job::Job(const GeminiRequest& request)
+    : m_request(request)
+{
+}
+
+Job::~Job()
+{
+}
+
+void Job::on_socket_connected()
+{
+    register_on_ready_to_write([this] {
+        if (m_sent_data)
+            return;
+        m_sent_data = true;
+        auto raw_request = m_request.to_raw_request();
+#ifdef JOB_DEBUG
+        dbg() << "Job: raw_request:";
+        dbg() << String::copy(raw_request).characters();
+#endif
+        bool success = write(raw_request);
+        if (!success)
+            deferred_invoke([this](auto&) { did_fail(Core::NetworkJob::Error::TransmissionFailed); });
+    });
+    register_on_ready_to_read([this] {
+        if (is_cancelled())
+            return;
+
+        if (m_state == State::InStatus) {
+            if (!can_read_line())
+                return;
+
+            auto line = read_line(PAGE_SIZE);
+            if (line.is_null()) {
+                fprintf(stderr, "Job: Expected status line\n");
+                return deferred_invoke([this](auto&) { did_fail(Core::NetworkJob::Error::TransmissionFailed); });
+            }
+
+            auto parts = String::copy(line, Chomp).split_limit(' ', 2);
+            if (parts.size() != 2) {
+                fprintf(stderr, "Job: Expected 2-part status line, got '%s'\n", line.data());
+                return deferred_invoke([this](auto&) { did_fail(Core::NetworkJob::Error::ProtocolFailed); });
+            }
+
+            bool ok;
+            m_status = parts[0].to_uint(ok);
+            if (!ok) {
+                fprintf(stderr, "Job: Expected numeric status code\n");
+                return deferred_invoke([this](auto&) { did_fail(Core::NetworkJob::Error::ProtocolFailed); });
+            }
+
+            m_meta = parts[1];
+
+            if (m_status >= 10 && m_status < 20) {
+                m_state = State::Finished;
+            } else if (m_status >= 20 && m_status < 30) {
+                m_state = State::InBody;
+            } else if (m_status >= 30 && m_status < 40) {
+                m_state = State::Finished;
+            } else if (m_status >= 40 && m_status < 50) {
+                m_state = State::Finished;
+            } else if (m_status >= 50 && m_status < 60) {
+                m_state = State::Finished;
+            } else if (m_status >= 60 && m_status < 70) {
+                m_state = State::InBody;
+            } else {
+                fprintf(stderr, "Job: Expected status between 10 and 69; instead got %d\n", m_status);
+                return deferred_invoke([this](auto&) { did_fail(Core::NetworkJob::Error::ProtocolFailed); });
+            }
+
+            return;
+        }
+
+        ASSERT(m_state == State::InBody || m_state == State::Finished);
+
+        read_while_data_available([&] {
+            auto read_size = 64 * KB;
+
+            auto payload = receive(read_size);
+            if (!payload) {
+                if (eof()) {
+                    finish_up();
+                    return IterationDecision::Break;
+                }
+
+                if (should_fail_on_empty_payload()) {
+                    deferred_invoke([this](auto&) { did_fail(Core::NetworkJob::Error::ProtocolFailed); });
+                    return IterationDecision::Break;
+                }
+            }
+
+            m_received_buffers.append(payload);
+            m_received_size += payload.size();
+
+            did_progress({}, m_received_size);
+
+            return IterationDecision::Continue;
+        });
+
+        if (!is_established()) {
+#ifdef JOB_DEBUG
+            dbg() << "Connection appears to have closed, finishing up";
+#endif
+            finish_up();
+        }
+    });
+}
+
+void Job::finish_up()
+{
+    m_state = State::Finished;
+    auto flattened_buffer = ByteBuffer::create_uninitialized(m_received_size);
+    u8* flat_ptr = flattened_buffer.data();
+    for (auto& received_buffer : m_received_buffers) {
+        memcpy(flat_ptr, received_buffer.data(), received_buffer.size());
+        flat_ptr += received_buffer.size();
+    }
+    m_received_buffers.clear();
+
+    auto response = GeminiResponse::create(m_status, m_meta, move(flattened_buffer));
+    deferred_invoke([this, response](auto&) {
+        did_finish(move(response));
+    });
+}
+}

Libraries/LibGemini/Job.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Optional.h>
+#include <LibCore/NetworkJob.h>
+#include <LibCore/TCPSocket.h>
+#include <LibGemini/GeminiRequest.h>
+#include <LibGemini/GeminiResponse.h>
+
+namespace Gemini {
+
+class Job : public Core::NetworkJob {
+public:
+    explicit Job(const GeminiRequest&);
+    virtual ~Job() override;
+
+    virtual void start() override = 0;
+    virtual void shutdown() override = 0;
+
+    GeminiResponse* response() { return static_cast<GeminiResponse*>(Core::NetworkJob::response()); }
+    const GeminiResponse* response() const { return static_cast<const GeminiResponse*>(Core::NetworkJob::response()); }
+
+protected:
+    void finish_up();
+    void on_socket_connected();
+    virtual void register_on_ready_to_read(Function<void()>) = 0;
+    virtual void register_on_ready_to_write(Function<void()>) = 0;
+    virtual bool can_read_line() const = 0;
+    virtual ByteBuffer read_line(size_t) = 0;
+    virtual bool can_read() const = 0;
+    virtual ByteBuffer receive(size_t) = 0;
+    virtual bool eof() const = 0;
+    virtual bool write(const ByteBuffer&) = 0;
+    virtual bool is_established() const = 0;
+    virtual bool should_fail_on_empty_payload() const { return false; }
+    virtual void read_while_data_available(Function<IterationDecision()> read) { read(); };
+
+    enum class State {
+        InStatus,
+        InBody,
+        Finished,
+    };
+
+    GeminiRequest m_request;
+    State m_state { State::InStatus };
+    int m_status { -1 };
+    String m_meta;
+    Vector<ByteBuffer> m_received_buffers;
+    size_t m_received_size { 0 };
+    bool m_sent_data { false };
+    bool m_should_have_payload { false };
+};
+
+}