I need help understanding some parts of an example sketch.
Posted: Tue Mar 16, 2021 5:29 pmI am in the very beginning stages of writing a program to control a neopixel strip. I want the user to be able to adjust program settings through a webpage using forms and ajax. I would like the user to be able to connect and access the webpage either through a connected network or by directly logging onto the esp8266.
One of the DNSServer library examples, CaptivePortalAdvanced, seem to cover accessing a webpage both ways like I wanted. Unfortunately I am confused about a few things and I have not had any luck finding the answers.
1. Why are the functions handleRoot and handleNotFound the only two server functions to call the function captivePortal? Why dont the functions handleWifi and handleWifiSave use the function captivePortal? If I add addition functions to handle server requests how will I know when to use captivePortal.
2. Why do the functions handleWifi and handleWifiSave need the line 'server.client().stop();' while handleRoot and handleNotFound do not need that line. If I add addition functions to handle server requests how will I know when to use 'server.client().stop();' in the function.
3. What do these lines do? Are they required? When is it appropriate to use them? Would I use them when sending AJAX data?
4. I'd like to add to this example to add some AJAX and interactions like turning a led on and off. I have no idea if sending requested data is different than sending whole web pages.
Here is the example I am referring to in case you dont want to follow the above link.
One of the DNSServer library examples, CaptivePortalAdvanced, seem to cover accessing a webpage both ways like I wanted. Unfortunately I am confused about a few things and I have not had any luck finding the answers.
1. Why are the functions handleRoot and handleNotFound the only two server functions to call the function captivePortal? Why dont the functions handleWifi and handleWifiSave use the function captivePortal? If I add addition functions to handle server requests how will I know when to use captivePortal.
2. Why do the functions handleWifi and handleWifiSave need the line 'server.client().stop();' while handleRoot and handleNotFound do not need that line. If I add addition functions to handle server requests how will I know when to use 'server.client().stop();' in the function.
3. What do these lines do? Are they required? When is it appropriate to use them? Would I use them when sending AJAX data?
Code: Select all
server.sendHeader("Cache-Control", "no-cache, no-store, must-revalidate");
server.sendHeader("Pragma", "no-cache");
server.sendHeader("Expires", "-1");
4. I'd like to add to this example to add some AJAX and interactions like turning a led on and off. I have no idea if sending requested data is different than sending whole web pages.
Here is the example I am referring to in case you dont want to follow the above link.
Code: Select all
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <DNSServer.h>
#include <ESP8266mDNS.h>
#include <EEPROM.h>
/*
This example serves a "hello world" on a WLAN and a SoftAP at the same time.
The SoftAP allow you to configure WLAN parameters at run time. They are not setup in the sketch but saved on EEPROM.
Connect your computer or cell phone to wifi network ESP_ap with password 12345678. A popup may appear and it allow you to go to WLAN config. If it does not then navigate to http://192.168.4.1/wifi and config it there.
Then wait for the module to connect to your wifi and take note of the WLAN IP it got. Then you can disconnect from ESP_ap and return to your regular WLAN.
Now the ESP8266 is in your network. You can reach it through http://192.168.x.x/ (the IP you took note of) or maybe at http://esp8266.local too.
This is a captive portal because through the softAP it will redirect any http request to http://192.168.4.1/
*/
/* Set these to your desired softAP credentials. They are not configurable at runtime */
#ifndef APSSID
#define APSSID "ESP_ap"
#define APPSK "12345678"
#endif
const char *softAP_ssid = APSSID;
const char *softAP_password = APPSK;
/* hostname for mDNS. Should work at least on windows. Try http://esp8266.local */
const char *myHostname = "esp8266";
/* Don't set this wifi credentials. They are configurated at runtime and stored on EEPROM */
char ssid[33] = "";
char password[65] = "";
// DNS server
const byte DNS_PORT = 53;
DNSServer dnsServer;
// Web server
ESP8266WebServer server(80);
/* Soft AP network parameters */
IPAddress apIP(172, 217, 28, 1);
IPAddress netMsk(255, 255, 255, 0);
/** Should I connect to WLAN asap? */
boolean connect;
/** Last time I tried to connect to WLAN */
unsigned long lastConnectTry = 0;
/** Current WLAN status */
unsigned int status = WL_IDLE_STATUS;
void setup() {
delay(1000);
Serial.begin(115200);
Serial.println();
Serial.println("Configuring access point...");
/* You can remove the password parameter if you want the AP to be open. */
WiFi.softAPConfig(apIP, apIP, netMsk);
WiFi.softAP(softAP_ssid, softAP_password);
delay(500); // Without delay I've seen the IP address blank
Serial.print("AP IP address: ");
Serial.println(WiFi.softAPIP());
/* Setup the DNS server redirecting all the domains to the apIP */
dnsServer.setErrorReplyCode(DNSReplyCode::NoError);
dnsServer.start(DNS_PORT, "*", apIP);
/* Setup web pages: root, wifi config pages, SO captive portal detectors and not found. */
server.on("/", handleRoot);
server.on("/wifi", handleWifi);
server.on("/wifisave", handleWifiSave);
server.on("/generate_204", handleRoot); //Android captive portal. Maybe not needed. Might be handled by notFound handler.
server.on("/fwlink", handleRoot); //Microsoft captive portal. Maybe not needed. Might be handled by notFound handler.
server.onNotFound(handleNotFound);
server.begin(); // Web server start
Serial.println("HTTP server started");
loadCredentials(); // Load WLAN credentials from network
connect = strlen(ssid) > 0; // Request WLAN connect if there is a SSID
}
void connectWifi() {
Serial.println("Connecting as wifi client...");
WiFi.disconnect();
WiFi.begin(ssid, password);
int connRes = WiFi.waitForConnectResult();
Serial.print("connRes: ");
Serial.println(connRes);
}
void loop() {
if (connect) {
Serial.println("Connect requested");
connect = false;
connectWifi();
lastConnectTry = millis();
}
{
unsigned int s = WiFi.status();
if (s == 0 && millis() > (lastConnectTry + 60000)) {
/* If WLAN disconnected and idle try to connect */
/* Don't set retry time too low as retry interfere the softAP operation */
connect = true;
}
if (status != s) { // WLAN status change
Serial.print("Status: ");
Serial.println(s);
status = s;
if (s == WL_CONNECTED) {
/* Just connected to WLAN */
Serial.println("");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
// Setup MDNS responder
if (!MDNS.begin(myHostname)) {
Serial.println("Error setting up MDNS responder!");
} else {
Serial.println("mDNS responder started");
// Add service to MDNS-SD
MDNS.addService("http", "tcp", 80);
}
} else if (s == WL_NO_SSID_AVAIL) {
WiFi.disconnect();
}
}
if (s == WL_CONNECTED) {
MDNS.update();
}
}
// Do work:
//DNS
dnsServer.processNextRequest();
//HTTP
server.handleClient();
}
/** Load WLAN credentials from EEPROM */
void loadCredentials() {
EEPROM.begin(512);
EEPROM.get(0, ssid);
EEPROM.get(0 + sizeof(ssid), password);
char ok[2 + 1];
EEPROM.get(0 + sizeof(ssid) + sizeof(password), ok);
EEPROM.end();
if (String(ok) != String("OK")) {
ssid[0] = 0;
password[0] = 0;
}
Serial.println("Recovered credentials:");
Serial.println(ssid);
Serial.println(strlen(password) > 0 ? "********" : "<no password>");
}
/** Store WLAN credentials to EEPROM */
void saveCredentials() {
EEPROM.begin(512);
EEPROM.put(0, ssid);
EEPROM.put(0 + sizeof(ssid), password);
char ok[2 + 1] = "OK";
EEPROM.put(0 + sizeof(ssid) + sizeof(password), ok);
EEPROM.commit();
EEPROM.end();
}
/** Handle root or redirect to captive portal */
void handleRoot() {
if (captivePortal()) { // If caprive portal redirect instead of displaying the page.
return;
}
server.sendHeader("Cache-Control", "no-cache, no-store, must-revalidate");
server.sendHeader("Pragma", "no-cache");
server.sendHeader("Expires", "-1");
String Page;
Page += F(
"<!DOCTYPE html><html lang='en'><head>"
"<meta name='viewport' content='width=device-width'>"
"<title>CaptivePortal</title></head><body>"
"<h1>HELLO WORLD!!</h1>");
if (server.client().localIP() == apIP) {
Page += String(F("<p>You are connected through the soft AP: ")) + softAP_ssid + F("</p>");
} else {
Page += String(F("<p>You are connected through the wifi network: ")) + ssid + F("</p>");
}
Page += F(
"<p>You may want to <a href='/wifi'>config the wifi connection</a>.</p>"
"</body></html>");
server.send(200, "text/html", Page);
}
/** Redirect to captive portal if we got a request for another domain. Return true in that case so the page handler do not try to handle the request again. */
boolean captivePortal() {
if (!isIp(server.hostHeader()) && server.hostHeader() != (String(myHostname) + ".local")) {
Serial.println("Request redirected to captive portal");
server.sendHeader("Location", String("http://") + toStringIp(server.client().localIP()), true);
server.send(302, "text/plain", ""); // Empty content inhibits Content-length header so we have to close the socket ourselves.
server.client().stop(); // Stop is needed because we sent no content length
return true;
}
return false;
}
/** Wifi config page handler */
void handleWifi() {
server.sendHeader("Cache-Control", "no-cache, no-store, must-revalidate");
server.sendHeader("Pragma", "no-cache");
server.sendHeader("Expires", "-1");
String Page;
Page += F(
"<!DOCTYPE html><html lang='en'><head>"
"<meta name='viewport' content='width=device-width'>"
"<title>CaptivePortal</title></head><body>"
"<h1>Wifi config</h1>");
if (server.client().localIP() == apIP) {
Page += String(F("<p>You are connected through the soft AP: ")) + softAP_ssid + F("</p>");
} else {
Page += String(F("<p>You are connected through the wifi network: ")) + ssid + F("</p>");
}
Page +=
String(F(
"\r\n<br />"
"<table><tr><th align='left'>SoftAP config</th></tr>"
"<tr><td>SSID ")) +
String(softAP_ssid) +
F("</td></tr>"
"<tr><td>IP ") +
toStringIp(WiFi.softAPIP()) +
F("</td></tr>"
"</table>"
"\r\n<br />"
"<table><tr><th align='left'>WLAN config</th></tr>"
"<tr><td>SSID ") +
String(ssid) +
F("</td></tr>"
"<tr><td>IP ") +
toStringIp(WiFi.localIP()) +
F("</td></tr>"
"</table>"
"\r\n<br />"
"<table><tr><th align='left'>WLAN list (refresh if any missing)</th></tr>");
Serial.println("scan start");
int n = WiFi.scanNetworks();
Serial.println("scan done");
if (n > 0) {
for (int i = 0; i < n; i++) {
Page += String(F("\r\n<tr><td>SSID ")) + WiFi.SSID(i) + ((WiFi.encryptionType(i) == ENC_TYPE_NONE) ? F(" ") : F(" *")) + F(" (") + WiFi.RSSI(i) + F(")</td></tr>");
}
} else {
Page += F("<tr><td>No WLAN found</td></tr>");
}
Page += F(
"</table>"
"\r\n<br /><form method='POST' action='wifisave'><h4>Connect to network:</h4>"
"<input type='text' placeholder='network' name='n'/>"
"<br /><input type='password' placeholder='password' name='p'/>"
"<br /><input type='submit' value='Connect/Disconnect'/></form>"
"<p>You may want to <a href='/'>return to the home page</a>.</p>"
"</body></html>");
server.send(200, "text/html", Page);
server.client().stop(); // Stop is needed because we sent no content length
}
/** Handle the WLAN save form and redirect to WLAN config page again */
void handleWifiSave() {
Serial.println("wifi save");
server.arg("n").toCharArray(ssid, sizeof(ssid) - 1);
server.arg("p").toCharArray(password, sizeof(password) - 1);
server.sendHeader("Location", "wifi", true);
server.sendHeader("Cache-Control", "no-cache, no-store, must-revalidate");
server.sendHeader("Pragma", "no-cache");
server.sendHeader("Expires", "-1");
server.send(302, "text/plain", ""); // Empty content inhibits Content-length header so we have to close the socket ourselves.
server.client().stop(); // Stop is needed because we sent no content length
saveCredentials();
connect = strlen(ssid) > 0; // Request WLAN connect with new credentials if there is a SSID
}
void handleNotFound() {
if (captivePortal()) { // If caprive portal redirect instead of displaying the error page.
return;
}
String message = F("File Not Found\n\n");
message += F("URI: ");
message += server.uri();
message += F("\nMethod: ");
message += (server.method() == HTTP_GET) ? "GET" : "POST";
message += F("\nArguments: ");
message += server.args();
message += F("\n");
for (uint8_t i = 0; i < server.args(); i++) {
message += String(F(" ")) + server.argName(i) + F(": ") + server.arg(i) + F("\n");
}
server.sendHeader("Cache-Control", "no-cache, no-store, must-revalidate");
server.sendHeader("Pragma", "no-cache");
server.sendHeader("Expires", "-1");
server.send(404, "text/plain", message);
}
/** Is this an IP? */
boolean isIp(String str) {
for (size_t i = 0; i < str.length(); i++) {
int c = str.charAt(i);
if (c != '.' && (c < '0' || c > '9')) {
return false;
}
}
return true;
}
/** IP to String? */
String toStringIp(IPAddress ip) {
String res = "";
for (int i = 0; i < 3; i++) {
res += String((ip >> (8 * i)) & 0xFF) + ".";
}
res += String(((ip >> 8 * 3)) & 0xFF);
return res;
}