Apologies for neglecting my branch! Thank you for picking this up. :)

Okay, got some final issues ironed out. This should be good to go now.

It occurred to me just now that this should probably be expanded to work on non-HTTP protocols.

You'll see that test 1119 and 1139 fail due to:

1. missing documentation for the new curl_easy_setopt option and
2. missing the new symbol in docs/libcurl/symbols-in-versions
3. I don't think there's a test for it (yet) but there's also missing documentation for the new command line option, isn't it?

Good points. I'll look into adding those.

Hi, I really would like to get this feature merged into curl and would be happy to help. @elyscape, please advice if I I can help you in any way. I have compiled and tested your fork, and it works just as I personally would expect.

vagrant@ldap:~/curl/curl$ ./src/.libs/curl -v --haproxy-protocol --resolve my.vhost.com:443:192.168.1.15 -k https://my.vhost.com:443/ 2>&1 | grep -E "subject:|expire date:"
*  subject: CN=my.vhost.com
*  expire date: Apr 11 18:16:03 2018 GMT

If there is any documentation I can do for you, I will happily help.

@maglub Sorry for the delay. I'll try to get the rest of the documentation done this week.

Rebased onto master again with documentation added.

If you run test 1119 and 1139 locally you'll see that they fail:

1119 - because docs/libcurl/symbols-in-versions isn't updated with your new symbol

1139 - because docs/libcurl/curl_easy_setopt.3 doesn't mention CURLOPT_HAPROXY_PROTOCOL.3 (referring to its "local" man page)

@bagder Tests fixed. I had put CURLOPT_HAPROXY_PROTOCOL in docs/libcurl/symbols-in-versions but CURLOPT_HAPROXYPROTOCOL everywhere else.

The red CI build is because CURLOPT_HAPROXYPROTOCOL.3 is not added to the tarball in the docs/libcurl/opts/Makfile.inc file.

@bagder Fixed and rebased onto master. Apologies for the delay; I was on vacation.

Ah, looks like the version I have in there is wrong. Let me know if everything else looks good and I can fix it.

Well, 7.59.0 came out before this got merged, so that concern is no longer relevant. Woo!

@bagder When you get a chance, please take another look at this. Thank you!

Thanks for all the work on this. Please try it out in the master branch now!