Hi,
I've noticed an application creating a new connection for each request in a set
when the target is the same. In this set of requests, the LOCALPORT/LOCALRANGE
has been specified for each request but INTERFACE has not. The application
cares about the local port range, but really doesn't care about the interfaces
and is happy to use the default value of NULL.
Some looking around leads me to:
lib/url.c ConnectionExists()
if(needle->localdev || needle->localport) {
/* If we are bound to a specific local end (IP+port), we must not
re-use a random other one, although if we didn't ask for a
particular one we can reuse one that was bound.
This comparison is a bit rough and too strict. Since the input
parameters can be specified in numerous ways and still end up the
same it would take a lot of processing to make it really accurate.
Instead, this matching will assume that re-uses of bound connections
will most likely also re-use the exact same binding parameters and
missing out a few edge cases shouldn't hurt anyone very much.
*/
if((check->localport != needle->localport) ||
(check->localportrange != needle->localportrange) ||
!check->localdev ||
!needle->localdev ||
strcmp(check->localdev, needle->localdev))
continue;
}
I would have guessed, prior to seeing this code, that a request for any
interface would have matched anything in the cache that matches the other
criteria. This code appears to explicitly exclude that possibility and is the
immediate cause of continual connection reconstruction for the case that I'm
seeing. Once seeing this, three possibilities came to mind. needle->localdev
being NULL should match anything; needle->localdev and check->localdev both
being NULL should match; or, finally, that the code is correct and there are
other considerations at work here that weren't clear to me. Hence, this email.
My question is, is this coded as intended or overly restrictive ? If the
former, I'd very much like to understand why so as to improve my understanding
of libcurl.
Thanks !
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