How to send a valid HTTP request to a Google Apps Script Web App?

Question

We sent an HTTP request from a C++ app (Arduino Sketck) to a Google apps script web app, but we got the HTTP Response: HTTP/1.1 302 Moved Temporarily. The url with the http request works fine from a browser.

The same code works also fine with other web site, like www.google.com. Do not work with script.google.com.

The Google apps script published web app is public, anyone even anonymous can access:

Here the code we used.

    client.println("GET /macros/s/AKfycbyQnmHekk4_NNy3Bl5ILzuSRkykMWaXQ7Rtojk7fFieDUbVqNM/exec?valore=7 HTTP/1.1");
    client.println("Host: script.google.com");
    client.println("Connection: close");
    client.println();

The answer was:


    HTTP/1.1 301 Moved Permanently
    Content-Type: text/html; charset=UTF-8
    Cache-Control: no-cache, no-store, max-age=0, must-revalidate
    Pragma: no-cache
    Expires: Mon, 01 Jan 1990 00:00:00 GMT
    Date: Wed, 03 Feb 2021 09:29:02 GMT
    Location: https://script.google.com/macros/s/AKfycbyQnmHekk4_NNy3Bl5ILzuSRkykMWaXQ7Rtojk7fFieDUbVqNM/exec?valore=7
    X-Content-Type-Options: nosniff
    X-Frame-Options: SAMEORIGIN
    Content-Security-Policy: frame-ancestors 'self'
    X-XSS-Protection: 1; mode=block
    Server: GSE
    Accept-Ranges: none
    Vary: Accept-Encoding
    Connection: close
    Transfer-Encoding: chunked
    11e
    <HTML>
    <HEAD>
    <TITLE>Moved Permanently</TITLE>
    </HEAD>
    <BODY BGCOLOR="#FFFFFF" TEXT="#000000">
    <H1>Moved Permanently</H1>
    The document has moved <A HREF="https://script.google.com/macros/s/AKfycbyQnmHekk4_NNy3Bl5ILzuSRkykMWaXQ7Rtojk7fFieDUbVqNM/exec?valore=7">here</A>.
    </BODY>
    </HTML>
    0
    disconnecting from server.

The url is correct ( http://script.google.com/macros/s/AKfycbyQnmHekk4_NNy3Bl5ILzuSRkykMWaXQ7Rtojk7fFieDUbVqNM/exec?valore=7) but seems that the google apps script web app redirect the request (to the same url, using the https protocol).

Using the same code, we did others HTTP request from Arduino, and it worked fine. For example we did:

    client.println("GET /search?q=arduino HTTP/1.1");
    client.println("Host: www.google.com");
    client.println("Connection: close");
    client.println();

And we got the response `` HTTP/1.1 200 OK ```, and the html response contains the search result according with the query q=arduino

Any suggestion on how we can send a valid http/https request to a Google apps script web app?

Thanks.

Remy Lebeau Remy Lebeau · Accepted Answer · 2021-02-03T18:56:57

As you have noticed, the Google script app is redirecting you from HTTP to HTTPS. Some Google sites are accessible via HTTP, they don't have to redirect to HTTPS if they don't want to. In your example, http://www.google.com/search?q=arduino does redirect, to https://www.google.com/search?q=arduino&gws_rd=ssl. But, your client is not sending a User-Agent header in the request, so Google knows your client is not a browser, and might not be issuing the redirect in your case. But in a real browser, it does.

Putting the URL http://script.google.com/macros/s/AKfycbyQnmHekk4_NNy3Bl5ILzuSRkykMWaXQ7Rtojk7fFieDUbVqNM/exec?valore=7 into a browser does redirect to https://script.google.com/macros/s/AKfycbyQnmHekk4_NNy3Bl5ILzuSRkykMWaXQ7Rtojk7fFieDUbVqNM/exec?valore=7. A real browser will follow that redirect automatically, a user might not even notice the difference.

But your client will have to follow the redirect manually. That means extracting the Location header from the response, closing the existing connection (to script.google.com on port 80), connecting to the specified server (script.google.com on port 443), and initiating an SSL/TLS encrypted session with the server before you can finally send the HTTP request.

SSL/TLS is complex, and HTTP has a lot of rules to it. Don't try to implement them manually. You are best off using an existing HTTP library that has HTTPS support built in. Let it handle all of these details for you.

How to send a valid HTTP request to a Google Apps Script Web App?

1 Answers