Synapse bug?
lazarus / 38-Networking and Web Programming

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BlueIcaro · 2022-04-22 13:19

Hello, I working in a program, which comunique with a server using
Get,Post, PUT, etc methods. Using Post method you have to send to a
server the Content-Type http header  with value application/x-www-
form-urlencoded. There is no problem when you using Post method with
Data Parameters. I write in my code before call HTTPMethod:
Code: [Select] Fht.MimeType := 'application/x-www-form-urlencoded';  
 Data Parameters are loaded in Document property of THttpsend object

But has some request  usign Post method with out Data Parameters. When
I do this, the server returns a error:

QuoteUNSUPPORTED_MEDIA(415) The server will not accept the request,
because the media type is not supported
So I was debuging and I found that sypnase code doesn't add the
Content-type Header  if you don't use DataParameter

Code: [Select]function THTTPSend.HTTPMethod(const Method, URL:
string): boolean // line 387 of httpsend Unit
(...)
  Sending := FDocument.Size > 0; 
(...)
  if Sending then
  begin
    FHeaders.Insert(0, 'Content-Length: ' +
IntToStr(InputDocument.Size));
    if FMimeType <> '' then
      FHeaders.Insert(0, 'Content-Type: ' + FMimeType);
  end;


This lines is the origin of my problem. So I changed it to:
Code: [Select]if Sending then
  begin
    FHeaders.Insert(0, 'Content-Length: ' + IntToStr(FDocument.Size));
  end;
  if FMimeType <> '' then
  begin
    FHeaders.Insert(0, 'Content-Type: ' + FMimeType);
  end;     

I don't know if this is a bug of Sypnase Library. Because I'm not a
expert in HTTP protocol. But After this fix I got a correct answer
from server.

If this is a bug, any one know how can I report this to author?

/BlueIcaro

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rvk · 2022-04-22 13:32

That seems to be a problem in the server. Why would you pass content-
type if there is no content to send.

https://www.rfc-editor.org/rfc/rfc7231#section-3.1.1.5
QuoteA sender that generates a message containing a payload body
SHOULD generate a Content-Type header field in that message unless the
intended media type of the enclosed representation is unknown to the
sender. If a Content-Type header field is not present, the recipient
MAY either assume a media type of "application/octet-stream"
([RFC2046], Section 4.5.1) or examine the data to determine its type.
Why are you using POST if there is no data to send? Won't a GET do the
same?

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BlueIcaro · 2022-04-22 14:07

Quote from: rvk on April 22, 2022, 03:32:42 pmThat seems to be a
problem in the server. Why would you pass content-type if there is no
content to send.

https://www.rfc-editor.org/rfc/rfc7231#section-3.1.1.5
QuoteA sender that generates a message containing a payload body
SHOULD generate a Content-Type header field in that message unless the
intended media type of the enclosed representation is unknown to the
sender. If a Content-Type header field is not present, the recipient
MAY either assume a media type of "application/octet-stream"
([RFC2046], Section 4.5.1) or examine the data to determine its type.
Why are you using POST if there is no data to send? Won't a GET do the
same?

Hi, that's we I asked if this is a bug of Sypnase library.
Acording to documentation of the server, which is a ABB Indutrial
Robot Controler
[https://developercenter.robotstudio.com/api/rwsApi/index.html
QuoteRobot Web Service currently use following content types:

    application/xhtml+xml For XML representation
    application/json For JSON representation
    application/x-www-form-urlencoded For "form data"

And when you send a command like this https://developercenter.robotstu
dio.com/api/rwsApi/elog_clearall_page.html where you can read:

QuoteMethod:
POST
URL Params:
action=clearall Required
Data Params:
None
(...)
curl --digest -u "Default User":robotics -X POST
"http://localhost/rw/elog?action=clearall"The server needs 'Content-
Type: ' with value  application/x-www-form-urlencoded even you send
any data, and all info is the url.

May be a wrong implementation on Server?. It's strange because ABB is
a swedish company, and the use to do the all thing according the
manual, rules, laws, etc.

/BlueIcaro

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rvk · 2022-04-22 14:17

And with other server implementations (like Medix) if you set the
content-type to application/x-www-form-urlencoded and you DON'T
provide any data/content, it will throw an error.

Quote from: BlueIcaro on April 22, 2022, 04:07:07 pmcurl --digest -u
"Default User":robotics -X POST
"http://localhost/rw/elog?action=clearall"

The server needs 'Content-Type: ' with value  application/x-www-form-
urlencoded even you send any data, and all info is the url.

May be a wrong implementation on Server?. It's strange because ABB is
a swedish company, and the use to do the all thing according the
manual, rules, laws, etc.
Did you test that curl statement?
Try it with an extra -v parameter.

curl -v --digest -u "Default User":robotics -X POST
"http://localhost/rw/elog?action=clearall"

Do you see any Content-Type being passed by curl ??? (I don't)
Code: [Select]* Server auth using Digest with user 'Default User'
> POST /rw/elog?action=clearall HTTP/1.1
> Host: localhost
> User-Agent: curl/7.74.0
> Accept: */*
>
So, does that throw an error for you?

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BlueIcaro · 2022-04-22 14:22

Hi,
I used curl (never used   before), and here is the output:
QuoteC:\Users\jorge>curl -v --digest -u "Default User":robotics -X
POST "http://localhost/rw/elog?action=clearall"
*   Trying 127.0.0.1:80...
* Connected to localhost (127.0.0.1) port 80 (#0)
* Server auth using Digest with user 'Default User'
> POST /rw/elog?action=clearall HTTP/1.1
> Host: localhost
> User-Agent: curl/7.79.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 401 Unauthorized
< Vary: Accept-Encoding
< X-Frame-Options: SAMEORIGIN
< Content-Type: text/plain
< X-Content-Type-Options: nosniff
< Date: Fri, 22 Apr 2022 14:20:16 GMT
< Cache-Control: no-cache
< Content-Length: 29
< X-XSS-Protection: 1; mode=block
< Connection: Keep-Alive
< WWW-Authenticate: Digest realm="validusers@robapi.abb", domain="/",
qop="auth", nonce="M2ViN2MxY2I0MDg5YWIwNzp2YWxpZHVzZXJzQHJvYmFwaS5hYmI
6MTgwNTFhNTFhMmE6MQ==", opaque="799d5", algorithm="MD5", stale="FALSE"
< Accept-Ranges: bytes
<
* Ignoring the response-body
* Connection #0 to host localhost left intact
* Issue another request to this URL:
'http://localhost/rw/elog?action=clearall'
* Found bundle for host localhost: 0x1a051d18da0 [serially]
* Re-using existing connection! (#0) with host localhost
* Connected to localhost (127.0.0.1) port 80 (#0)
* Server auth using Digest with user 'Default User'
> POST /rw/elog?action=clearall HTTP/1.1
> Host: localhost
> Authorization: Digest username="Default User",realm="validusers@roba
pi.abb",nonce="M2ViN2MxY2I0MDg5YWIwNzp2YWxpZHVzZXJzQHJvYmFwaS5hYmI6MTg
wNTFhNTFhMmE6MQ==",uri="/rw/elog?action=clearall",cnonce="921882676e0b
845dc36edabdd01bf4ee",nc=00000001,algorithm=MD5,response="e86208c737f4
f8d8c17f89eb178c2e46",qop="auth",opaque="799d5"
> User-Agent: curl/7.79.1
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 415 Unsupported Media Type
< Set-Cookie: -http-
session-=2::http.session::838cdb68c4aa8a5dadd9afd880f23dfb; path=/;
httponly
< Set-Cookie: ABBCX=13; path=/; httponly
< Vary: Accept-Encoding
< X-Frame-Options: SAMEORIGIN
< Content-Type: application/xhtml+xml
< X-Content-Type-Options: nosniff
< Date: Fri, 22 Apr 2022 14:20:16 GMT
< Cache-Control: no-cache="set-cookie", max-age=0, no-cache, no-store
< Content-Length: 417
< X-XSS-Protection: 1; mode=block
< Connection: Keep-Alive
< Pragma: no-cache
< Expires: -1
< Accept-Ranges: bytes
<
<?xml version="1.0" encoding="UTF-8"?><html
xmlns="http://www.w3.org/1999/xhtml"><head><title>rw</title><base
href="http://localhost:80/"/></head><body><div class="status"><span
class="code">-1073414146</span><span class="msg">d:\workspaces\robotso
ftware\kernel\6.08.xx\areas\robapi2\components\rws_elogsrv\rws_resourc
e_elog.cpp[409] content type is not supported code:-1073414146
icode:415</span></div></body></html>* Connection #0 to host localhost
left intact

/BlueIcaro

Edit: Using the example of documentation. So there is same thing
weird. So I going to report to ABB.

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rvk · 2022-04-22 14:33

Quote from: BlueIcaro on April 22, 2022, 04:22:47 pmEdit: Using the
example of documentation. So there is same thing weird. So I going to
report to ABB.
Yeah... if their own example also give that same error...

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BlueIcaro · 2022-04-22 14:42

Thanks for all rvk.

I was fighting with this two days. I read the examples using curl and
I never test them 

Curl command gives me more info. Why I never used 

I wrote a post in ABB oficial forum
(https://forums.robotstudio.com/discussion/13427/rws-clear-all-log-
sample-from-documentation-fails#latest), If I have news I'll write
report here. May be can help some one more in future.

Now I sure that is not a bug from Synapse package.

/BlueIcaro