Why does ESP8266 report DNS fail when loading php URL?

Question

Using an ESP8266 and using the following AT commands I can successfully get the webpage:

AT+CIPSTART="TCP","www.somewebsite.com",80
AT+CIPSEND=80
> GET http://www.somewebsite.com HTTP/1.0
<I get a bunch of HTML here>

So far so good. Now I have a php page on my website that takes a few parameters and updates a table in a database accordingly. So when I type:

http ://www.mywebsite.com/mypage.php?arg1=one&arg2=two

It successfully updates the table. Now when I try to use ESP8266 to do the same I get a DNS fail:

AT+CIPSTART="TCP","http://www.mywebsite.com/mypage.php?arg1=one&arg2=two",80
<get DNS fail here>

Even if I try the php page without the arguments I get DNS fail:

AT+CIPSTART="TCP","http://www.mywebsite.com/mypage.php",80
<get DNS fail here>

Does anyone know what's going on? Could it be that the php page is not on port 80? And if that's the case, how do I find out what port it's on?

By the way, if I do the same with an html page on my website it works just fine.

EDIT: When I try this:

AT+CIPSTART="TCP","www.mywebsite.com",80
> GET /mypage.php?arg1=one,arg2=two

I get this output:

Error 404 - Not Found

And when I try:

AT+CIPSTART="TCP","www.mywebsite.com",80
> GET http://www.mywebsite.com/mypage.php?arg1=one,arg2=two

I get the html code of www.mywebsite.com/index.html and not the php page.

I'm also not sure what the "HTTP/1.0" in the GET command does?

The argument is just supposed to be the domain name of the website. The rest of the URL goes after GET. — Barmar
– Barmar, Commented Mar 29, 2016 at 4:23

Barmar · Accepted Answer · 2016-03-29 04:50:53Z

7

You don't put the URL on the AT+CIPSTART line, that just wants the name of the server. The rest of the URL goes after GET. Also, if your server does virtual hosting, you need to send a Host: header to tell it which server name to use.

AT+CIPSTART="TCP","www.mywebsite.com",80
> GET /mypage.php?arg1=one&arg2=two HTTP/1.1
> Host: www.mywebsite.com

edited Mar 29, 2016 at 4:50

answered Mar 29, 2016 at 4:24

Barmar

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3 Comments

Arash Fotouhi Over a year ago

Thanks. I tried this and I get an error 404 page not found. I've added the commands I ran and the output to the original question.

Barmar Over a year ago

I've updated the answer to include the Host: header, which is required to distinguish virtual servers.

Arash Fotouhi Over a year ago

Thanks for the great answer. It worked! I also found this command on stackoverflow (can't find the source so please post here if you do find it): <echo -en 'GET /mypage.php?arg1=one&arg2=two HTTP/1.1\r\nHost: www.mywebsite.com\r\n\r\n' | nc bluefoxnano.com 80'> to run in the terminal. This way you can send HTTP commands. I found it great for testing out the commands before programming the ESP8266.

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