Configure a DHCP softAP for wireless modem using ESP32

Question

I have configured the soft AP for the wireless modem connected with ESP32 which receive the values from the wireless sensor network to serve a web page at 192.168.1.77. this webpage is made to save the ipv4 settings. Here on the landing page, I have given two options to select DHCP or static IP settings.

I am able to select and save static IP, gateway and subnet settings and later configuring it to softAP.

But while in DHCP mode, It is still taking last configured values that are 192.168.1.77 even though it has to take 192.168.4.1.

Kindly have a look at my code and web form

#include <WiFi.h>
#include "FS.h"
#include "SPIFFS.h"
#include <WebServer.h>

WebServer server(80);

//**********check for connection*************/
bool isConnected = true;
bool isDisconnect = false;

//**********softAPconfig Timer*************/
unsigned long APTimer = 0;
unsigned long APInterval = 120000;

//*********SSID and Pass for AP**************/
const char *ssidAP = "ESPuser";
const char *ssidAPWeb = "ESPWebUser";
const char *ssidDhcpWeb = "ESPDHCPUser";
const char *passDhcpWeb = "1234567";


//*********Static IP Config**************/
IPAddress ap_local_IP(192,168,1,77);
IPAddress ap_gateway(192,168,1,254);
IPAddress ap_subnet(255,255,255,0);

//*********Static IP WebConfig**************/
IPAddress ap_localWeb_IP;
IPAddress ap_Webgateway;
IPAddress ap_Websubnet;
IPAddress ap_dhcpWeb_IP;

uint8_t ip0;
uint8_t ip1;
uint8_t ip2;
uint8_t ip3;

//*********IP Char Array**************/
char ipv4Arr[20];
char gatewayArr[20];           
char subnetArr[20];
char ipv4dhcpArr[20];

void setup()
{   
  Serial.begin(9600);
  while(!Serial);
  WiFi.disconnect(true);
  WiFi.mode(WIFI_AP);
  Serial.println(WiFi.softAP(ssidAP) ? "soft-AP setup": "Failed to connect");
  delay(100);
  Serial.println(WiFi.softAPConfig(ap_local_IP, ap_gateway, ap_subnet)? "Configuring Soft AP" : "Error in Configuration");    
  Serial.println(WiFi.softAPIP());
    SPIFFS.begin();

    server.begin();

    server.on("/", handleRoot); 
    server.on("/dhcp", handleDHCP);
    server.on("/static", handleStatic);
    server.onNotFound(handleNotFound);  

    APTimer = millis();

    while(isConnected && millis()-APTimer<= APInterval) {
        server.handleClient();  }       
}


void loop()
{
  Serial.println(WiFi.softAPIP());
  delay(500);

}

//****************************HANDLE ROOT***************************//
void handleRoot() {
   //Redisplay the form
   if(server.args()>0){
       for(int i=0; i<=server.args();i++){
          Serial.println(String(server.argName(i))+'\t' + String(server.arg(i)));
        }
     if(server.hasArg("ipv4static") && server.hasArg("gateway") &&  server.hasArg("subnet")){
      staticSet();
      }else if(server.arg("ipv4")!= ""){
          dhcpSetManual();
        }else{
           dhcpSetDefault();
          }    
    }else{
      File file = SPIFFS.open("/Select_Settings.html", "r");
         server.streamFile(file,"text/html");
         file.close();
      }
}


void handleDHCP(){
  File  file = SPIFFS.open("/page_dhcp.html", "r");
  server.streamFile(file,"text/html");
  file.close();}

void handleStatic(){
  File  file = SPIFFS.open("/page_static.html", "r");
  server.streamFile(file,"text/html");
  file.close();}

void staticSet(){

           String response="<p>The static ip is ";
           response += server.arg("ipv4static");
           response +="<br>";
           response +="The gateway ip is ";
           response +=server.arg("gateway");
           response +="<br>";
           response +="The subnet Mask is ";
           response +=server.arg("subnet");
           response +="</P><BR>";
           response +="<H2><a href=\"/\">go home</a></H2><br>";
           response += "<script> alert(\"Settings Saved\"); </script>";
           server.send(200, "text/html", response);
           String ipv4static = String(server.arg("ipv4static"));
           String gateway = String(server.arg("gateway"));
           String subnet = String(server.arg("subnet"));
           ipv4static.toCharArray(ipv4Arr,sizeof(ipv4static)+2);
           gateway.toCharArray(gatewayArr,sizeof(gateway)+2);
           subnet.toCharArray(subnetArr,sizeof(subnet)+2);
           byte ip[4];
           parseBytes(ipv4Arr,'.', ip, 4, 10);
           ip0 = (uint8_t)ip[0];
           ip1 = (uint8_t)ip[1];
           ip2 = (uint8_t)ip[2];
           ip3 = (uint8_t)ip[3];
           IPAddress ap_local(ip0,ip1,ip2,ip3);
           ap_localWeb_IP = ap_local;
           parseBytes(gatewayArr,'.', ip, 4, 10);
           ip0 = (uint8_t)ip[0];
           ip1 = (uint8_t)ip[1];
           ip2 = (uint8_t)ip[2];
           ip3 = (uint8_t)ip[3];
           IPAddress ap_gate(ip0,ip1,ip2,ip3);
           ap_Webgateway = ap_gate;
           parseBytes(subnetArr,'.', ip, 4, 10);
           ip0 = (uint8_t)ip[0];
           ip1 = (uint8_t)ip[1];
           ip2 = (uint8_t)ip[2];
           ip3 = (uint8_t)ip[3];
           IPAddress ap_net(ip0,ip1,ip2,ip3);  
           ap_Websubnet= ap_net;

           WiFi.disconnect(true);
           WiFi.mode(WIFI_AP);   
           Serial.println(WiFi.softAP(ssidAPWeb) ? "Setting up SoftAP" : "error setting up");
           delay(100);
           while(!(WiFi.softAPIP()== ap_localWeb_IP)){
               Serial.println(WiFi.softAPConfig(ap_localWeb_IP, ap_gate, ap_net) ? "Configuring softAP" : "kya yaar not connected");    
       }
    isConnected = false;     
    }

void dhcpSetManual(){
           String response="<p>The dhcp IPv4 address is ";
           response += server.arg("ipv4");
           response +="</P><BR>";
           response +="<H2><a href=\"/\">go home</a></H2><br>";
           response += "<script> alert(\"Settings Saved\"); </script>";
           server.send(200, "text/html", response);
           WiFi.disconnect(true);
           WiFi.mode(WIFI_AP);
           Serial.println(WiFi.softAP(ssidDhcpWeb, passDhcpWeb) ? "Setting up SoftAP" : "error setting up");
           delay(100);
           while(!(WiFi.softAPIP()== ap_dhcp)){
            Serial.println(WiFi.softAPConfig(ap_dhcp, ap_gateway,ap_subnet) ? "Configuring DHCP" : "error configuring");
           }     

           isConnected = false;        
  }

void dhcpSetDefault(){
           String response="<p>The dhcp IPv4 address is ";
           response += server.arg("configure");
           response +="</P><BR>";
           response +="<H2><a href=\"/\">go home</a></H2><br>";
           response += "<script> alert(\"Settings Saved\"); </script>";
           server.send(200, "text/html", response);
           WiFi.disconnect(true);
           WiFi.mode(WIFI_AP);
           Serial.println(WiFi.softAP(ssidDhcpWeb, passDhcpWeb) ? "Setting up SoftAP" : "error setting up");
           delay(100);
           while(!(WiFi.softAPIP()== ap_dhcp)){
            Serial.println(WiFi.softAPConfig(ap_dhcp, ap_gateway,ap_subnet) ? "Configuring DHCP" : "error configuring");
           }     

           isConnected = false;          
      }

//****************HANDLE NOT FOUND*********************//
void handleNotFound()
{
  String message = "File Not Found\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET)?"GET":"POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i=0; i<server.args(); i++){
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  message +="<H2><a href=\"/\">go home</a></H2><br>";
  server.send(404, "text/plain", message);
}

void parseBytes(const char* str, char sep, byte* bytes, int maxBytes, int base) {
    for (int i = 0; i < maxBytes; i++) {
        bytes[i] = strtoul(str, NULL, base);  // Convert byte
        str = strchr(str, sep);               // Find next separator
        if (str == NULL || *str == '\0') {
            break;                            // No more separators, exit
        }
        str++;                                // Point to next character after separator
    }
}

Your advice on this will be a great help.

Answer 1

I can see that you are using passDhcpWeb for softAP passkey but it only contains 7 characters whereas according to WiFiAP.cpp the password length should be 8 characters. this might be a cause of your problem and regarding disconnection, I was also facing the same problem. I resolved it by using

WiFi.disconnect(false); Wifi.enabeAP(false);