added basic commands

README.md

@@ -4,3 +4,64 @@ A toy implementation of a Redis-like server in C++.
 This is a learning project for me to understand how Redis works internally. It is not intended for production use.
 
 Thanks to [Build-your-own-X](https://github.com/codecrafters-io/build-your-own-x) repository for helping me get started with this project!
+
+
+# Building
+
+Requirements:
+- A C++17 compatible compiler (e.g., g++, clang++)
+- CMake 3.10 or higher
+- Python 3.10 or higher (for the client)
+
+```bash
+cmake . && make
+```
+
+Now you can run the server:
+
+```bash
+./my_own_redis
+```
+
+# Client
+
+In ```Build-your-own-X``` client and server were written on C/C++. But I decided to write a simple client in Python for easier testing and just because I like Python.
+
+You can run the client like this:
+
+```bash
+uv run ./client.py
+
+# Help
+uv run ./client.py --help
+```
+
+# Server protocol
+
+The server uses a simple binary protocol over TCP.
+Each command is sent as:
+- 4 bytes: total length of the command (excluding this length field)
+- 4 bytes: number of arguments (N)
+- For each argument:
+  - 4 bytes: length of the argument (L)
+  - L bytes: argument data
+
+The server responds with:
+- 4 bytes: total length of the response (excluding this length field)
+- 4 bytes: status code (0 = OK, 2 = NX, 1 = ERR)
+- Remaining bytes: response message (if any)
+
+## Commands
+
+Currently supported commands:
+- `SET key value`: Sets the value for the given key.
+- `GET key`: Gets the value for the given key.
+- `DEL key`: Deletes the given key.
+
+
+# Afterwords
+
+I don't plan to make this project more complex, but I might add some features in the future. And I don't know if you would find this project useful, but feel free to use it as a learning resource or a starting point for your own projects!
+Enjoy coding!
+Love yourself!
+Be happy! ☺️

client.py

@@ -1,3 +1,4 @@
+import shlex
 import socket
 import struct
 import argparse
@@ -24,32 +25,61 @@ def recv_exact(sock: socket.socket, n: int) -> bytes:
         data += chunk
     return data
 
-def send_frame(sock: socket.socket, payload: bytes) -> None:
-    header = struct.pack('!I', len(payload))
-    sock.sendall(header + payload)
+def send_command(sock: socket.socket, text: str) -> None:
+    parts = shlex.split(text)
+    if not parts:
+        return
+    
+    chunks = []
+    
+    n_args = len(parts)
+    chunks.append(struct.pack('!I', n_args))
+    
+    for part in parts:
+        part_bytes = part.encode()
+        chunks.append(struct.pack('!I', len(part_bytes)))
+        chunks.append(part_bytes)
+        
+    payload = b''.join(chunks)
+    
+    sock.sendall(struct.pack('!I', len(payload)) + payload)
 
-def recv_frame(sock: socket.socket) -> bytes:
+def recv_response(sock: socket.socket) -> str:
     header = recv_exact(sock, 4)
     (length,) = struct.unpack('!I', header)
     if length > 10_000_000:
         raise ValueError('Message length is too long')
-    return recv_exact(sock, length)
+    
+    body = recv_exact(sock, length)
+    if length < 4:
+         raise ValueError("Response too short")
+         
+    (status,) = struct.unpack('!I', body[:4])
+    msg = body[4:]
+    
+    if status == 0:
+        if not msg:
+            return "(ok)"
+        return msg.decode("utf-8", errors='replace')
+    elif status == 2:
+        return "(nil)"
+    else:
+        return f"(err) {msg.decode('utf-8', errors='replace')}"
 
 def main():
     print_logo()
     parser = argparse.ArgumentParser(description='NOT(Redis) client')
     parser.add_argument('-H', '--host', type=str, required=False, default='127.0.0.1', help='Server host')
     parser.add_argument('-P', '--port', type=int, required=False, default=6379, help='Server port')
-    parser.add_argument('-M', '--message', type=str, required=False, default=None, help='Message to send (if not provided, starts interactive shell)')
+    parser.add_argument('-M', '--message', type=str, required=False, default=None, help='Command to send (e.g. "set k v")')
     args = parser.parse_args()
 
     try:
         with socket.create_connection((args.host, args.port)) as sock:
             if args.message:
-                send_frame(sock, args.message.encode())
-                response = recv_frame(sock)
-                print('Message sent:', args.message)
-                print('Server says:', response.decode("utf-8", errors='replace'))
+                send_command(sock, args.message)
+                response = recv_response(sock)
+                print(response)
             else:
                 print(f"Connected to {args.host}:{args.port}")
                 print("Type 'quit' or 'exit' to leave.")
@@ -66,9 +96,9 @@ def main():
                         if cmd_line.lower() in ('quit', 'exit'):
                             break
                         
-                        send_frame(sock, cmd_line.encode())
-                        response = recv_frame(sock)
-                        print(response.decode("utf-8", errors='replace'))
+                        send_command(sock, cmd_line)
+                        response = recv_response(sock)
+                        print(response)
                         
                     except KeyboardInterrupt:
                         print("\nType 'quit' or 'exit' to leave.")

src/command_parser.hpp

@@ -0,0 +1,3 @@
+// TODO: Implemented command parsing logic outside of server.cpp
+// This file can be expanded in the future for more complex command parsing needs.
+

src/constants.hpp

@@ -3,3 +3,9 @@
 #include <stdint.h>
 
 const uint32_t k_max_message_size = 4096;
+
+enum {
+    RES_OK = 0,
+    RES_ERR = 1,
+    RES_NX = 2,
+};

src/server.cpp

@@ -160,22 +160,96 @@ void Server::state_res(Connection* conn) {
     }
 }
 
+static int32_t parse_req(
+    const uint8_t* data, size_t len, std::vector<std::string>& out) 
+{
+    if (len < 4) {
+        return -1;
+    }
+    uint32_t n = 0;
+    memcpy(&n, data, 4);
+    n = ntohl(n);
+    size_t pos = 4;
+    while (n--) {
+        if (pos + 4 > len) {
+            return -1;
+        }
+        uint32_t sz = 0;
+        memcpy(&sz, data + pos, 4);
+        sz = ntohl(sz);
+        pos += 4;
+        if (pos + sz > len) {
+            return -1;
+        }
+        out.push_back(std::string((char*)&data[pos], sz));
+        pos += sz;
+    }
+    if (pos != len) {
+        return -1;
+    }
+    return 0;
+}
+
 int32_t Server::parse_and_execute(Connection* conn) {
     uint32_t len_net;
     memcpy(&len_net, conn->incoming.data(), 4);
     uint32_t len = ntohl(len_net);
     
-    std::string message(conn->incoming.begin() + 4, conn->incoming.begin() + 4 + len);
-    Logger::log_info("Client (fd=" + std::to_string(conn->connectionfd) + ") says: " + message);
+    std::vector<std::string> cmd;
+    if (parse_req(conn->incoming.data() + 4, len, cmd) != 0) {
+        Logger::log_error("bad request");
+        return -1;
+    }
+
+    uint32_t status = RES_OK;
+    std::string msg;
+
+    if (cmd.empty()) {
+        status = RES_ERR;
+        msg = "Empty command";
+    } else {
+        std::string name = cmd[0];
+        if (name == "set") {
+            if (cmd.size() == 3) {
+                g_data[cmd[1]] = cmd[2];
+            } else {
+                status = RES_ERR;
+                msg = "Usage: set key value";
+            }
+        } else if (name == "get") {
+            if (cmd.size() == 2) {
+                auto it = g_data.find(cmd[1]);
+                if (it == g_data.end()) {
+                    status = RES_NX;
+                } else {
+                    msg = it->second;
+                }
+            } else {
+                status = RES_ERR;
+                msg = "Usage: get key";    
+            }
+        } else if (name == "del") {
+            if (cmd.size() == 2) {
+                g_data.erase(cmd[1]);
+            } else {
+                status = RES_ERR;
+                msg = "Usage: del key";
+            }
+        } else {
+            status = RES_ERR;
+            msg = "Unknown command: " + name;
+        }
+    }
     
-    const std::string reply = "world";
-    uint32_t reply_len = static_cast<uint32_t>(reply.size());
-    uint32_t reply_len_net = htonl(reply_len);
+    uint32_t reply_len = (uint32_t)msg.size();
+    uint32_t total_len = 4 + reply_len;
     
-    const char* header_ptr = reinterpret_cast<const char*>(&reply_len_net);
-    conn->outgoing.insert(conn->outgoing.end(), header_ptr, header_ptr + 4);
+    uint32_t total_len_net = htonl(total_len);
+    uint32_t status_net = htonl(status);
     
-    conn->outgoing.insert(conn->outgoing.end(), reply.begin(), reply.end());
+    conn->outgoing.insert(conn->outgoing.end(), (char*)&total_len_net, (char*)&total_len_net + 4);
+    conn->outgoing.insert(conn->outgoing.end(), (char*)&status_net, (char*)&status_net + 4);
+    conn->outgoing.insert(conn->outgoing.end(), msg.begin(), msg.end());
     
     conn->state = STATE_RES;
     return 0;

src/server.hpp

@@ -35,6 +35,8 @@ private:
     std::vector<struct pollfd> poll_args;
     std::map<int, Connection*> fd2conn;
 
+    std::map<std::string, std::string> g_data;
+
     void setup();
     void accept_new_connection();
     void connection_io(Connection* conn);