How to POST to a RESTful API on an ESP8266 using authentication?

Question

I can enter this URL from a browser, and after entering my credentials this successfully calls my API http://172.16.0.40/rest/vars/set/1/12/666.

I'm trying to do this from an an ESP8266 using HTTPClient. My credentials are username:password, and I used an online conversion utility to get dXNlcm5hbWU6cGFzc3dvcmQ=.

When executed, the following returns error 701 (no idea what that is).

HTTPClient http;
http.begin("172.16.0.40", 80, "/");
http.addHeader("Content-Type", "text/plain");
http.addHeader("Authorization", "dXNlcm5hbWU6cGFzc3dvcmQ=");
auto httpCode = http.POST("rest/vars/set/1/12/999");

If I comment out the Authorization header, I get a 401, which is unauthorized access. What am I doing wrong?

I rolled back your edit, because answer becomes not understandable as you add "Basic" that answer suggest to add. If then you have an other problem, it is better to post an new post about this, rather than modifing the subject of this one. — mpromonet, Dec 17 '16 at 12:38

score 6 · Accepted Answer · answered Dec 16 '16 at 15:31

You are trying to do a POST request to http://172.16.0.40/ with rest/vars/set/1/12/999 as payload.

HTTP status code 701 is not a standard code and is probably server specific.

You probably meant to do:

HTTPClient http;
http.begin("172.16.0.40", 80, "/rest/vars/set/1/12/999");
http.addHeader("Content-Type", "text/plain");
http.addHeader("Authorization", "Basic dXNlcm5hbWU6cGFzc3dvcmQ=");
auto httpCode = http.POST(payload);

If you want a GET request, call http.GET() instead of http.POST(payload) and you should get the same response as inside the browser.

Edit:
And as @MaximilianGerhardt already answered, you need to prepend Basic to your Authorization header.

The **GET** worked! Out of curiosity, I'm not sure what to use for **payload**. — WhiskerBiscuit, Dec 16 '16 at 15:51
POST is for saving data. The payload would be the data to be saved. And that depends on the API. — gre_gor, Dec 16 '16 at 15:55

score 3 · Answer 2 · answered Dec 16 '16 at 15:31

The header of such an authorization must look like (Wikipedia):

Authorization: Basic d2lraTpwZWRpYQ==

In short, you're probably just missing the "Basic" part. And need do change your code to

http.addHeader("Authorization", "Basic dXNlcm5hbWU6cGFzc3dvcmQ=");

How to POST to a RESTful API on an ESP8266 using authentication?

2 Answers2