Re: Callback for socket options in curl + c-ares

[Francisco Sedano Crippa (fsedanoc)]

Hi folks,
I went ahead and created a patch to provide a new libcurl CB, that will be 
called just before a new resolver is called, and the resolver data (channel in 
case of cares) is passed. This solves the problem perfectly for my use case.
 
Initially I thought about just adding a new easy_getinfo option to retrieve it, 
but since libcurl can create easy_handles on it's own, I feel this callback 
approach is a safer option.

Are you guys OK with that approach? If that's ok I can send the pull request 
for review.

Thanks,

. .:|:.:|:. Francisco Sedano  | CCIE 14859, Tech Lead Software Engineering | 
CSG Enterprise Access and Services Group (EASG)
 
On 14.02.18, 00:54, "curl-library on behalf of Francisco Sedano Crippa 
(fsedanoc)"  
wrote:

Hello Daniel,

I feel it would be useful in some other cases - for example dealing with 
multi-vrf sockets, currently you can bind the libcurl socket to any vrf you 
want, but no way to do that with the underlying c-ares.

Wouldn't be enough to provide access to the c-ares channel (which is in 
curl_easy->state.resolver if I'm not wrong)? Once I create my easy socket and 
the c-ares channel is created, I could just use 
ares_set_socket_configure_callback on the channel and I'd be done. Anything 
else I'm missing?

Thanks,


. .:|:.:|:. Francisco Sedano  | CCIE 14859, Tech Lead Software Engineering 
| CSG Enterprise Access and Services Group (EASG)
 
On 13.02.18, 23:49, "curl-library on behalf of Daniel Stenberg" 
 wrote:

On Tue, 13 Feb 2018, Francisco Sedano Crippa (fsedanoc) wrote:

> Ideally I’d like to setup a callback with 
> ares_set_socket_configure_callback(), but in order to do so, I need 
access 
> to internal libcurl c-ares channel, which is embedded in the 
Curl_easy 
> structure.
>
> Is there any way to access such c-ares channel so I can properly 
intercept 
> c-ares socket usage, like we can do with CURLOPT_OPENSOCKETFUNCTION 
in 
> libcurl?

No, that's something we've not felt the need for before... I can't 
think of 
any other way to offer such a feature than to add a special and 
dedicated "set 
socket options" callback for c-ares or perhaps rather for "the resolver 
back-end". (There's work ongoing in making the resolver back-end 
totally 
pluggable which then possibly also appreciate such an ability.)

-- 

  / daniel.haxx.se


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Re: Callback for socket options in curl + c-ares

[Francisco Sedano Crippa (fsedanoc)]

Hello Daniel,

I feel it would be useful in some other cases - for example dealing with 
multi-vrf sockets, currently you can bind the libcurl socket to any vrf you 
want, but no way to do that with the underlying c-ares.

Wouldn't be enough to provide access to the c-ares channel (which is in 
curl_easy->state.resolver if I'm not wrong)? Once I create my easy socket and 
the c-ares channel is created, I could just use 
ares_set_socket_configure_callback on the channel and I'd be done. Anything 
else I'm missing?

Thanks,


. .:|:.:|:. Francisco Sedano  | CCIE 14859, Tech Lead Software Engineering | 
CSG Enterprise Access and Services Group (EASG)
 
On 13.02.18, 23:49, "curl-library on behalf of Daniel Stenberg" 
 wrote:

On Tue, 13 Feb 2018, Francisco Sedano Crippa (fsedanoc) wrote:

> Ideally I’d like to setup a callback with 
> ares_set_socket_configure_callback(), but in order to do so, I need 
access 
> to internal libcurl c-ares channel, which is embedded in the Curl_easy 
> structure.
>
> Is there any way to access such c-ares channel so I can properly 
intercept 
> c-ares socket usage, like we can do with CURLOPT_OPENSOCKETFUNCTION in 
> libcurl?

No, that's something we've not felt the need for before... I can't think of 
any other way to offer such a feature than to add a special and dedicated 
"set 
socket options" callback for c-ares or perhaps rather for "the resolver 
back-end". (There's work ongoing in making the resolver back-end totally 
pluggable which then possibly also appreciate such an ability.)

-- 

  / daniel.haxx.se


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Re: Callback for socket options in curl + c-ares

[Daniel Stenberg]

On Tue, 13 Feb 2018, Francisco Sedano Crippa (fsedanoc) wrote:

Ideally I’d like to setup a callback with 
ares_set_socket_configure_callback(), but in order to do so, I need access 
to internal libcurl c-ares channel, which is embedded in the Curl_easy 
structure.


Is there any way to access such c-ares channel so I can properly intercept 
c-ares socket usage, like we can do with CURLOPT_OPENSOCKETFUNCTION in 
libcurl?


No, that's something we've not felt the need for before... I can't think of 
any other way to offer such a feature than to add a special and dedicated "set 
socket options" callback for c-ares or perhaps rather for "the resolver 
back-end". (There's work ongoing in making the resolver back-end totally 
pluggable which then possibly also appreciate such an ability.)


--

 / daniel.haxx.se---
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