Peter Siegmund
1fbc28a628
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- save wifi data - show status led Signed-off-by: Peter Siegmund <developer@mars3142.org>
80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
// Minimaler DNS-Server für Captive Portal (alle Anfragen auf AP-IP)
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// Quelle: https://github.com/espressif/esp-idf/blob/master/examples/protocols/sntp/main/dns_server.c (angepasst)
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#include <arpa/inet.h>
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#include <esp_log.h>
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#include <freertos/FreeRTOS.h>
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#include <freertos/task.h>
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#include <lwip/inet.h>
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#include <lwip/sockets.h>
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#include <netinet/in.h>
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#include <string.h>
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#include <sys/socket.h>
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#define DNS_PORT 53
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#define DNS_MAX_LEN 512
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static const char *TAG = "dns_hijack";
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static char s_ap_ip[16] = "192.168.4.1"; // Default AP-IP, ggf. dynamisch setzen
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void dns_set_ap_ip(const char *ip)
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{
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strncpy(s_ap_ip, ip, sizeof(s_ap_ip) - 1);
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s_ap_ip[sizeof(s_ap_ip) - 1] = 0;
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}
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static void dns_server_task(void *pvParameters)
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{
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int sock = socket(AF_INET, SOCK_DGRAM, 0);
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if (sock < 0)
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{
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ESP_LOGE(TAG, "Failed to create socket");
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vTaskDelete(NULL);
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return;
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}
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struct sockaddr_in server_addr = {0};
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server_addr.sin_family = AF_INET;
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server_addr.sin_port = htons(DNS_PORT);
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server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
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bind(sock, (struct sockaddr *)&server_addr, sizeof(server_addr));
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uint8_t buf[DNS_MAX_LEN];
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while (1)
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{
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struct sockaddr_in from;
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socklen_t fromlen = sizeof(from);
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int len = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *)&from, &fromlen);
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if (len < 0)
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continue;
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// DNS Header: 12 bytes, Antwort-Flag setzen
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buf[2] |= 0x80; // QR=1 (Antwort)
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buf[3] = 0x80; // RA=1, RCODE=0
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// Fragen: 1, Antworten: 1
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buf[7] = 1;
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// Antwort anhängen (Name Pointer auf Frage)
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int pos = len;
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buf[pos++] = 0xC0;
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buf[pos++] = 0x0C; // Name pointer
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buf[pos++] = 0x00;
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buf[pos++] = 0x01; // Type A
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buf[pos++] = 0x00;
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buf[pos++] = 0x01; // Class IN
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buf[pos++] = 0x00;
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buf[pos++] = 0x00;
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buf[pos++] = 0x00;
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buf[pos++] = 0x3C; // TTL 60s
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buf[pos++] = 0x00;
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buf[pos++] = 0x04; // Data length
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inet_pton(AF_INET, s_ap_ip, &buf[pos]);
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pos += 4;
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sendto(sock, buf, pos, 0, (struct sockaddr *)&from, fromlen);
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}
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close(sock);
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vTaskDelete(NULL);
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}
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void dns_server_start(const char *ap_ip)
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{
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dns_set_ap_ip(ap_ip);
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xTaskCreate(dns_server_task, "dns_server", 4096, NULL, 3, NULL);
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}
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