add some code

managed_components/78__esp-wifi-connect/dns_server.cc

@@ -0,0 +1,75 @@
+#include "dns_server.h"
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+#include <esp_log.h>
+#include <lwip/sockets.h>
+#include <lwip/netdb.h>
+
+#define TAG "DnsServer"
+
+DnsServer::DnsServer() {
+}
+
+DnsServer::~DnsServer() {
+}
+
+void DnsServer::Start(esp_ip4_addr_t gateway) {
+    ESP_LOGI(TAG, "Starting DNS server");
+    gateway_ = gateway;
+
+    fd_ = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+    if (fd_ < 0) {
+        ESP_LOGE(TAG, "Failed to create socket");
+        return;
+    }
+
+    struct sockaddr_in server_addr;
+    memset(&server_addr, 0, sizeof(server_addr));
+    server_addr.sin_family = AF_INET;
+    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+    server_addr.sin_port = htons(port_);
+
+    if (bind(fd_, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
+        ESP_LOGE(TAG, "failed to bind port %d", port_);
+        close(fd_);
+        return;
+    }
+
+    xTaskCreate([](void* arg) {
+        DnsServer* dns_server = static_cast<DnsServer*>(arg);
+        dns_server->Run();
+    }, "DnsServerTask", 4096, this, 5, NULL);
+}
+
+void DnsServer::Stop() {
+    ESP_LOGI(TAG, "Stopping DNS server");
+}
+
+void DnsServer::Run() {
+    char buffer[512];
+    while (1) {
+        struct sockaddr_in client_addr;
+        socklen_t client_addr_len = sizeof(client_addr);
+        int len = recvfrom(fd_, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &client_addr_len);
+        if (len < 0) {
+            ESP_LOGE(TAG, "recvfrom failed, errno=%d", errno);
+            continue;
+        }
+
+        // Simple DNS response: point all queries to 192.168.4.1
+        buffer[2] |= 0x80;  // Set response flag
+        buffer[3] |= 0x80;  // Set Recursion Available
+        buffer[7] = 1;      // Set answer count to 1
+
+        // Add answer section
+        memcpy(&buffer[len], "\xc0\x0c", 2);  // Name pointer
+        len += 2;
+        memcpy(&buffer[len], "\x00\x01\x00\x01\x00\x00\x00\x1c\x00\x04", 10);  // Type, class, TTL, data length
+        len += 10;
+        memcpy(&buffer[len], &gateway_.addr, 4);  // 192.168.4.1
+        len += 4;
+        ESP_LOGI(TAG, "Sending DNS response to %s", inet_ntoa(gateway_.addr));
+
+        sendto(fd_, buffer, len, 0, (struct sockaddr *)&client_addr, client_addr_len);
+    }
+}