Use Ipv4 address for port checker

[dylansama]

Pass --ipv4 parameter to curl to use Ipv4 address, when checking for ports. The port checker websites do not support Ipv6.

[dylansama]

Technically the preferIpv4 feature could be expanded to http portion of Snoopy client as well, since curl options are exclusively for https requests. It seems the only major changes would be in the connect() function, when creating a socket context you would bind to 0:0 which will only match ipv4 addresses, whereas [0]:0 (or possibly [::]:0) will match an ipv6 address per docs.

If there is any desire for that as well. I see very few things nowadays not using https though.

[dylansama]

Fixes #2402

[dylansama]

Added support for preferIpv4 on plain http requests as well. Switching to the more diverse function stream_socket_client over fsockopen for all requests. Guessing the function check for stream_socket_client was from very ancient PHP 4.x days. As noted before simply need to set bindTo option to 0:0 rather than letting system choose.

[stickz]

Added Work In Progress label. Looking for changes and to disable by default to reduce the chances of a regression.

Anther pull request will be required with improvements to enable the feature by default. Snoppy we need to be improved. 0:0 is not a good way to bind to the IPV4 address. This will create a regression if a static IP address is assigned for torrents. Please don't address this issue in the current pull request. We want to merge a more minimal set of changes first into ruTorrent.

[stickz]

Target changed to version 4.1 stable. Version 4.0 stable is being released next week.

[dylansama]

Added Work In Progress label. Looking for changes and to disable by default to reduce the chances of a regression.

Anther pull request will be required with improvements to enable the feature by default. Snoppy we need to be improved. 0:0 is not a good way to bind to the IPV4 address. This will create a regression if a static IP address is assigned for torrents. Please don't address this issue in the current pull request. We want to merge a more minimal set of changes first into ruTorrent.

Yeah perhaps we could just skip the feature altogether for insecure http requests? I was just toying around to make it "feature complete" for Snoopy client between both http and https. Specifically this PR is really just for fixing the check_port plugin and both of the sites in the plugin use only https anyways. So all the stream context binding stuff is really un-used, the only truly useful change is the curl paramter --ipv4.

[stickz]

@dylansama I edited your pull request and squash merged the changes into version 4.0 stable. I wanted to show you how to create an effective pull request. The useIpv4 feature is enabled by default. There is no risk of regression.

If you would like to make additional improvements, please create a new pull request.