I tried checking erros for each library API call and found that setting
CONNECT_ONLY option itself fails.

This is what I tried,
/
if((res=curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1)) != CURLE_OK)
{
      printf("Error setting CURLOPT_CONNECT_ONLY[%d][%s]\n",
CURLOPT_CONNECT_ONLY, curl_easy_strerror(res));
      exit(1);
}

/Getting following output,,
/Error setting CURLOPT_CONNECT_ONLY[141][failed init]

/Tried to findout in curl code what really happens.
curl_easy_setopt------->Curl_setopt passing it value of
/CURLOPT_CONNECT_ONLY which is set to 141 (via CINIT(CONNECT_ONLY, LONG,
141), inside curl/curl.h)

/Inside function /Curl_setopt( lib/url.c), /there is a /case
CURLOPT_CONNECT_ONLY:/ available, but it seems code flow doesn't follow
it and enters /default: /case and returns an error for 'failed init'.

Am I missing something here !

--
Nilesh
Karl M wrote:
> Hi Nilesh...
>
> I don't expect a difference with 7.15.2 versus 7.15.3, but your tests 
> will verify that.
>
> CURLOPT_CONNECT_ONLY allows curl to set up the connection, but not 
> perform any transfer of data. Typically the application then gets the 
> socket by getting info with the CURLINFO_LASTSOCKET option. After 
> that, the application performs its own custom transfer.
>
> HTH,
>
> ...Karl
>
>> From: Nilesh Subject: Re: Patch for CURLOPT_CONNECT_ONLY
>> Date: Wed, 22 Mar 2006 10:35:57 +0530
>>
>> Thanks Karl !
>>
>> I think only difference here is curl version I was trying with 7.15.2 
>> and you tried with 7.15.3
>>
>> Let me try the same code again with my test webserver and also check 
>> the error code at each step.
>>
>> As you said same curl handle cannot be used for HTTP POST, what is 
>> the use of CONNECT_ONLY option ?
>> May be I am not clear on use of this feature. What I understood and 
>> wanted to do is as follows,
>>
>> - With first perform I can check if connection can be established 
>> with webserver.
>> - Only after successfull connection establishment, I can transfer 
>> data using same curl handle. Ofcourse while doing data transfer, 
>> connection may go down, that time perform call may fail which is fine.
>>
>> If not CONNECT_ONLY, what is the way I can get above implemented.
>>
>> Thanks again for your kind involvement into this.
>>
>> Thanks,
>> Nilesh
>>
>> Karl M wrote:
>>
>>> Hi All...
>>>
>>> I just tried the following code with 7.15.3 and MSVC on an XP Pro 
>>> machine:
>>>
>>> #include <fcntl.h>
>>> #include <io.h>
>>> #include <curl/curl.h>
>>>
>>> #if LIBCURL_VERSION_NUM < 0x070f02
>>> #error "Requires libcurl version 7.15.2 or higher."
>>> #endif
>>>
>>> int main(void) {
>>>  CURL *curl;
>>>  CURLcode res;
>>>  long last_sock=0;
>>>
>>>  char *postthis="moo mooo moo moo";
>>>
>>>  curl = curl_easy_init();
>>>  if(curl) {
>>>    curl_easy_setopt(curl, CURLOPT_URL, "http://yahoo.com");
>>>    curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1);
>>>
>>>    res = curl_easy_perform(curl);
>>>    res = curl_easy_getinfo(curl, CURLINFO_LASTSOCKET, &last_sock);
>>>    printf("Return code frm curl_easy_getinfo [%d][%s]\n", res, 
>>> curl_easy_strerror(res)); // this gives res=43
>>>    printf("curl_easy_getinfo returned CURLINFO_LASTSOCKET [%ld]\n", 
>>> last_sock); // last_sock is still 0
>>>    if(CURLE_OK == res) {
>>>      printf("curl_easy_getinfo returned CURLINFO_LASTSOCKET 
>>> [%ld]\n", last_sock);
>>>    }
>>>
>>>   //curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postthis);
>>>
>>>   /* if we don't provide POSTFIELDSIZE, libcurl will strlen() by
>>>      itself */
>>>   //curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(postthis));
>>>
>>>   //res = curl_easy_perform(curl);
>>>
>>>   /* always cleanup */
>>>   curl_easy_cleanup(curl);
>>>  }
>>>  return 0;
>>> }
>>>
>>> and got the following output:
>>>
>>> Return code frm curl_easy_getinfo [0][no error]
>>> curl_easy_getinfo returned CURLINFO_LASTSOCKET [1940]
>>> curl_easy_getinfo returned CURLINFO_LASTSOCKET [1940]
>>>
>>> I commented out the second half of your code because with 
>>> CURLOPT_CONNECT_ONLY, I don't think the put could work on the same 
>>> curl handle.
>>>
>>> Does your testwebserver exist?
>>>
>>> Perhaps you could check the error code at each step and see where 
>>> something first goes wrong.
>>>
>>> HTH,
>>>
>>> ...Karl
>>>
>>>> From: Nilesh
>>>> Subject: Re: Patch for CURLOPT_CONNECT_ONLY
>>>> Date: Fri, 17 Mar 2006 11:55:55 +0530
>>>>
>>>>
>>>>
>>>>>> Also if I can get working example for this option, that will be 
>>>>>> helpful.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> I would like that too, for inclusion in the package.
>>>>
>>>>
>>>>
>>>> Following is what I am trying to do to test CONNECT_ONLY option. ( 
>>>> I used simplepost.c example with small modification )
>>>>
>>>> /int main(void)
>>>> {
>>>>  CURL *curl;
>>>>  CURLcode res;
>>>>  long last_sock=0;
>>>>
>>>>  char *postthis="moo mooo moo moo";
>>>>
>>>>  curl = curl_easy_init();
>>>>  if(curl) {
>>>> *    curl_easy_setopt(curl, CURLOPT_URL, "http://testwebserver");
>>>>    curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1);
>>>>
>>>>    res = curl_easy_perform(curl);
>>>>    res = curl_easy_getinfo(curl, CURLINFO_LASTSOCKET, &last_sock);
>>>>    printf("Return code frm curl_easy_getinfo [%d][%s]\n", res, 
>>>> curl_easy_strerror(res)); // this gives res=43
>>>>    printf("curl_easy_getinfo returned CURLINFO_LASTSOCKET [%ld]\n", 
>>>> last_sock); // last_sock is still 0
>>>>    if(CURLE_OK == res)
>>>>    {
>>>>        printf("curl_easy_getinfo returned CURLINFO_LASTSOCKET 
>>>> [%ld]\n", last_sock);
>>>>    }
>>>> *
>>>>    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postthis);
>>>>
>>>>    /* if we don't provide POSTFIELDSIZE, libcurl will strlen() by
>>>>       itself */
>>>>    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(postthis));
>>>>
>>>>    res = curl_easy_perform(curl);
>>>>
>>>>    /* always cleanup */
>>>>    curl_easy_cleanup(curl);
>>>>  }
>>>>  return 0;
>>>> }
>>>> /
>>>> Getting following output:
>>>>
>>>> */Return code frm curl_easy_getinfo [43][a libcurl function was 
>>>> given a bad argument]
>>>> curl_easy_getinfo returned CURLINFO_LASTSOCKET [0]
>>>> /
>>>> *Can you help me to understand how CONNECT_ONLY be used ?
>>>>
>>>> Thanks,
>>>> Nilesh
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>
>
>