From: Daniel Stenberg <daniel_at_haxx.se>
>On Fri, 16 Mar 2012, Elli? Computing Open Source Program wrote:
>>> lib/url.c:ConnectionExists() is the function that checks if a new
>>> request
>>> can re-use an existing connection.
>>
>> I have a problem, when I try to access check->data members it seems that
>> I
>> get default values, and not those provided when the original SFTP request
>> happened. Am I right?
>No, you're not. The connectdata struct is associated with a physical
>connection. Each such connectdata is either independent (like when put in
>the
>connection pool within a multi handle) or associated with a SessionHandle
>(->data points to that). There is never any SessionHandle struct kept
>around
>with just default values.
OK, I understand my scenario better now, here is what happens:
- start a connection to a "site" 1 (some kind of "server+auth info"
structure)
- finish the job, and keep the CURL* easy handle in a list for reuse, reset
it
- start a connection to a site 2 very similar to previous one, only auth
info changes
- ConnectionExists reuses connection to site 1, because server + user/pwd
match (but not AUTH_TYPES)

>> should I use another SessionHandle / "data"?
>
>You compare connections, that means fields of two connectdata structs. The
>SessionHandle is basically where values are copied from to the connectdata
>struct at the time that struct is allocated and most likely the connections
>you compare point to the same SessionHandle struct.

I understand now why I cannot use check->data member as it can be modified
by the user, and the reason why it was all defaults was because of my own
code.

>> Part of the authentication information is indeed provided inside
>> "data->set"
>> with the combination of being "statefully authenticated" on the contrary
>> to
>> most other protocols.
>
>If that is true that it is a bug. The values in 'data->set' are what was
>set
>by the user with setopt() and they must remain like that. If libcurl needs
>to
>update anything, that anything needs to be somewhere else. If a connection
>needs to remember any value from data->set, then that data needs to be
>stored
>in the connectdata struct so that you can compare..

for connection reuse of SFTP/SCP we need to copy during connection the
authentication
related options, else we cannot know if those options changed since last
request.
It includes almost all CURLSSH_OPT_?? excluding the KEYFUNCTION/KEYDATA.
where should I copy them? inside ssh_conn structure?

may other protocols be touched by that remark? (i.e. stateful authentication
=> authentication info copied in connectdata)

Regards
Armel

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Received on 2012-03-19