feat: implement UDPClient class for non-blocking UDP communication

main/network/udp_client.h

@@ -0,0 +1,83 @@
+#pragma once
+
+#include <string>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include "esp_err.h"
+
+/**
+ * @brief UDP client for sending commands and receiving responses
+ *
+ * Implements non-blocking UDP communication with configurable timeouts.
+ * Socket remains open for the lifetime of the instance.
+ */
+class UDPClient {
+public:
+    UDPClient();
+    ~UDPClient();
+
+    /**
+     * @brief Initialize UDP socket
+     * @return ESP_OK on success, error code otherwise
+     */
+    esp_err_t init();
+
+    /**
+     * @brief Configure remote endpoint
+     * @param ip Remote IP address (e.g., "192.168.50.201")
+     * @param port Remote port number (e.g., 4211)
+     * @return ESP_OK on success, ESP_ERR_INVALID_ARG if IP is invalid
+     */
+    esp_err_t configure(const std::string& ip, uint16_t port);
+
+    /**
+     * @brief Send command to remote endpoint
+     * @param command Command string to send (e.g., "TOGGLE", "STATUS", "MUTE", "UNMUTE")
+     * @return ESP_OK on success, ESP_FAIL if not configured or send failed
+     */
+    esp_err_t send_command(const std::string& command);
+
+    /**
+     * @brief Receive response from remote endpoint (non-blocking)
+     * @param response Output string for received data
+     * @param timeout_ms Timeout in milliseconds (0 = no wait, -1 = wait forever)
+     * @return ESP_OK on success, ESP_ERR_TIMEOUT on timeout, ESP_FAIL on error
+     */
+    esp_err_t receive_response(std::string& response, int timeout_ms = 1000);
+
+    /**
+     * @brief Check if client is configured with valid endpoint
+     * @return true if IP and port are configured
+     */
+    bool is_configured() const { return configured_; }
+
+    /**
+     * @brief Get current remote IP
+     */
+    std::string get_ip() const { return remote_ip_; }
+
+    /**
+     * @brief Get current remote port
+     */
+    uint16_t get_port() const { return remote_port_; }
+
+    /**
+     * @brief Close socket and reset configuration
+     */
+    void close();
+
+private:
+    int sock_fd_;                  // Socket file descriptor
+    struct sockaddr_in remote_addr_; // Remote endpoint address
+    std::string remote_ip_;         // Remote IP address
+    uint16_t remote_port_;          // Remote port number
+    bool configured_;               // Whether endpoint is configured
+    bool initialized_;              // Whether socket is initialized
+
+    /**
+     * @brief Set socket to non-blocking mode
+     * @return ESP_OK on success
+     */
+    esp_err_t set_nonblocking();
+};