SSL access through a proxy causes SIGSEGV

[yosh-matsuda]

I've found that GET requests via proxy cause SIGSEGV for SSL access.

@yhirose Could you review the following and the PR?

How to reproduce

OS: Ubuntu 22.04.2 (x86_64)

Set up Squid.

$ docker run -d --name squid-container -e TZ=JST -p 3128:3128 ubuntu/squid:5.2-22.04_beta

Code to reproduce.

Client cli("https://www.yahoo.com");
cli.set_proxy("localhost", 3128);
auto res = cli.Get("/");

Detail

It seems that the problem is originated in the commit c7e959a at the ClientImpl::process_request function. I don't understand the implementation details around that code, but it is probably due to the lack of a socket open check, and this seems to fix SIGSEGV.

[yhirose]

@yosh-matsuda thanks for the bug report and pull request. I tested it on my Mac and this pull request didn't fix the crash on macOS at f4b02df. I fixed it in a different way, and confirmed that it now fixes the problem on macOS. Could you test it on your linux environment? Then, I'll bump up the version number.
Thanks for your help!

[yosh-matsuda]

@yhirose Thank you very much. It works fine on my Ubuntu.

[yhirose]

@yosh-matsuda this fix is included in v0.12.2. Thanks for your fine contribution. 👍