https://curl.haxx.se//mail/lib-2018-08/0137.html
myLC--- via curl-library wrote:
Hello, :-)
I'm new to (lib)curl. I decided that this was the most
complete network implementation, after ditching Qt for
continuous multithreading issues.
I would like to know how we can retrieve all the IP
addresses which are mapped to a host.
Assuming we have the URL
https://example.buzz/bingo_results/
and assuming further that there are 5 addresses mapped to
this hostname:
10.0.0.11, 10.0.0.12, 10.0.0.13,
fd0e:34f4:760f:5bd6:0123:4567:89ab:cdef,
fd0e:34f4:760f:5bd6:aaaa:bbbb:cccc:dddd
How would I get them from libcurl?
The "inbound" network implementation (TR) of C++ (Boost
ASIO) returns an iterator upon having resolved a hostname.
If I'm correct, the implementation chooses the IP randomly
when connecting. Likewise, it tries the entire list of IPs
before giving up. I haven't checked out libcurl's source-
code, but I'm guessing that you will do something similar.
Virtually all the functions for resolving hostnames return
all the addresses (getaddrinfo, for instance).
Therefore, at some point, libcurl must have this
information. So, how do I get that list of all addresses?
I'm inquiring, because I would hate to employ a second
engine/dispatcher for this.
I'm confused about what it is you are trying to do with the list of addresses?
- connect to each one and perform an operation?
- try to connect (simultaneously?) to several and find
the first one that works?
Are you asking libcurl to do a normal operation on a given host URL with host
name and oh, BTW, return whatever address list libcurl resolved?? This seems
like a highly specialized feature to add to libcurl.
It's not clear to me why you are trying to get libcurl to return that address
list. If you are on a modern system, you already have a way to do this:
getaddrinfo() or equivalent.
I guess I'm wondering if it makes more sense for your application to get the
list of addresses itself and then tell libcurl what to do with them. Is it
good enough to create URLs with each IP literal? Perhaps what you are looking
for is a way to perform the same operation on a given URL but with different
IP addresses? (All hosts see the same textual host name?) Possibly
simultaneously via multi?
Or have I totally missed something? To have discussions go right into API
details suggests that this is of more value than I thought, even though I
don't really understand why.
Cheers!
Rich
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