From 9580a9a8daa4426914f396a694903ab880ecd3f2 Mon Sep 17 00:00:00 2001
From: Oxore <oxore@protonmail.com>
Date: Sat, 27 Aug 2022 15:12:08 +0300
Subject: Add initial gdbremote implementation

---
 gdbremote_parser.hpp | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 gdbremote_parser.hpp

(limited to 'gdbremote_parser.hpp')

diff --git a/gdbremote_parser.hpp b/gdbremote_parser.hpp
new file mode 100644
index 0000000..0e2f375
--- /dev/null
+++ b/gdbremote_parser.hpp
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: Unlicense
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <vector>
+#include <memory>
+
+namespace GDBRemote {
+
+enum class FeatureSupportMark: uint8_t {
+    kNone = 0,
+    kPlus,
+    kMinus,
+    kQuestion,
+};
+
+enum class FeatureName: int {
+    kUnknown = 0,
+    kMultiprocess,
+    kSoftwareBreak,
+    kHardwareBreak,
+    kQRelocInsn,
+    kForkEvents,
+    kVForkEvents,
+    kExecEvents,
+    kVContSuppurted,
+    kQThreadEvents,
+    kNoResumed,
+    kMemoryTagging,
+    kPacketSize,
+};
+
+struct Feature {
+    const FeatureName name{};
+    const FeatureSupportMark mark{};
+    const bool has_value{};
+    const int value{};
+    const std::string raw{};
+};
+
+enum class PacketType: int {
+    kNone = 0,
+    kQuerySupported,
+    kQueryC,
+    kQueryFThreadInfo,
+    kQuerySThreadInfo,
+    kH,
+    kMustReplyEmpty,
+};
+
+struct PacketData {
+    PacketData() = delete;
+    PacketData(const PacketData&) = delete;
+    PacketData(PacketData&&) = delete;
+    virtual ~PacketData() {}
+};
+
+struct PacketDataSupportedFeatures: public PacketData {
+    std::vector<Feature> features{};
+    virtual ~PacketDataSupportedFeatures() {}
+};
+
+struct Packet {
+    const PacketType type{};
+    const std::unique_ptr<PacketData> data;
+
+    /** Convert raw packet data into a Packet
+     *
+     * Packet data is the data extracted by ExchangeContext::Consume function.
+     */
+    static Packet Parse(std::string packet_data);
+};
+
+struct ExchangeResult {
+    const std::string packet{};
+    const std::string response{};
+
+    ExchangeResult(std::string a_packet, std::string a_response)
+        : packet(a_packet), response(a_response) {}
+
+    static std::unique_ptr<ExchangeResult> Nak(std::string data=std::string{})
+    {
+        return std::make_unique<ExchangeResult>(data, std::string{"-"});
+    }
+
+    static std::unique_ptr<ExchangeResult> Ack(std::string data=std::string{})
+    {
+        return std::make_unique<ExchangeResult>(data, std::string{"+"});
+    }
+};
+
+class ExchangeContext {
+public:
+    /** Consume next byte from input stream from GDB client
+     *
+     * Returns packet data and acknowledge response in case if a valid packet
+     * fully received.
+     *
+     * Returns nullptr if is in progress.
+     */
+    std::unique_ptr<ExchangeResult> Consume(uint8_t byte);
+
+    /** Creates raw packet from packet data to be sent into socket directly
+     *
+     * It is not static nor const because after sending a packet an
+     * ExchangeContext must be set into awaiting acknowledge response state
+     * (i.e. '+' or '-'). Otherwise we will be unable to resend packet in case
+     * if '-' negative acknowledge is received.
+     */
+    std::string WrapDataToSend(Packet packet=Packet{});
+
+private:
+    enum class ParsingState {
+        kIdle,
+        kPacketData,
+        kPacketDataBinSecond,
+        kChecksum1,
+        kChecksum2,
+    };
+
+    void transit(ParsingState);
+    static const char* parsingStateToString(ParsingState state);
+
+    ParsingState _parsing_state{ParsingState::kIdle};
+    std::string _packet_data{};
+    uint8_t _checksum{};
+    uint8_t _given_checksum_first_byte{};
+};
+
+}
-- 
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