Russell Bateman

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6 years, 3 months ago.

ESP8266 - Respond to a HTTP POST Request from a webpage

Hi guys,

At the moment I have written an application running on an STM32F411RE which uses an ESP8266 to serve a configuration webpage to a browser. Currently the user can enter information into the form and submit it. The data from the form reaches the ESP8266 and STM32F411RE as expected which I then parse and send back a HTTP OK response e.g.

#define ESP8266_HTTP_OK "HTTP/1.1 200 OK\r\n"

This response is reaching the browser (verified with the debugger in Google Chrome) however when I send the HTML page back to the browser nothing seems to happen.

In my serveBuffer() function I have hard coded the connection parameter to the 0th connection which may cause issues. Here is the implementation:

int serveBuffer(const char* bufferToSend, int len){
    int ret = ESP8266_FAIL_NO_GOOD_RESPONSE;
    int offset = 0;
    char recv[255] = {0};
    char serialBuffer[255] = {0};
    bool readyToSend = false;
    esp.printf("AT+CIPSEND=0,%d\r\n", len);
    readResponse(recv, sizeof(recv), 1);
    for(int i = 0; ((i < sizeof(recv)) && readyToSend == false); i++){
        if(recv[i] == '>'){
            readyToSend = true;
        }
    }
    
    if(readyToSend){
        while(len > 0){
            strncpy(serialBuffer, &bufferToSend[offset], sizeof(serialBuffer));
            esp.printf("%s", serialBuffer);
            offset += strlen(serialBuffer);
            len -= (strlen(serialBuffer) + 1);
            memset(serialBuffer, '\0', sizeof(serialBuffer));
        }
        pc.printf("\n");
        ret = readResponse(recv, sizeof(recv), 1);
    }
    return ret;
}

Here is how I'm currently handling the request:

int handleClientWebRequest(){
    char buffer[255] = {0};
    char numBuf[4] = {0};
    int ret;
   //... other data vars
    readResponse(buffer, sizeof(buffer), 1);

    if(strstr(buffer, "GET")){
        ret = ESP8266_RECV_REQUEST;              
    }
    else if(strstr(buffer, HOUR_KEY)){
          //parse fields
         ret = ESP8266_ALARM_REQUEST;
        readResponse(buffer, sizeof(buffer), 1);
        serveBuffer(ESP8266_HTTP_OK, strlen(ESP8266_HTTP_OK));
        serveBuffer(CONFIG_PAGE, strlen(CONFIG_PAGE));
        closeConnection();
    }
    else{
        ret = ESP8266_NO_REQUEST;
    }
    return ret;
}

Then only way I can get the config page back after a submit is to close down the browser tab and re-request the page. Are these steps correct or should I try to handle it in a different manner?

Any assistance with this would be much appreciated!

Thanks, Russell Bateman

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