Fixing Cygwin's SSL issues with git clone c_rehash bug

Cygwin’s git clone drama

Oh, you.

When I am working on Windows for the various reasons which compel one to work on Windows I often use Cygwin to provide UNIX-like functionality on the command line (cmd.exe leaves a lot to be desired). Since a vital part of my workflow on any OS is git I happily installed git using the Install.exe workflow that Cygwin provides.

To my surprise (and, I’m not going to deny it, slight nerd-rage) when I attempted to git clone a repository from Github I was greeted by an error message like this one:

$ git clone https://github.com/foo/bar
error: SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

OK, so I have an SSL issue. Running through the Setup.exe with Cygwin again and installing ca-certificates and openssl didn’t fix it, and eventually I came across this Stack Overflow post which described my exact issue.

On the hunt for solutions

One proposed solution

$ git config --global http.sslVerify false

SERIOUSLY!?!?

No way I’m going to turn off SSL just to try and workaround this issue. I don’t like getting MITMed.

A much better proposed solution

Also from Stack Overflow:

$ cd /usr/ssl/certs
$  curl http://curl.haxx.se/ca/cacert.pem | awk 'split_after==1{n++;split_after=0} /-----END CERTIFICATE-----/ {split_after=1} {print > "cert" n ".pem"}'
$ c_rehash

OK, this is headed in the right direction, I can tell. I had to manually create the /usr/ssl/certs directory (probably because I hadn’t installed OpenSSL yet when I tried this), but even after getting OpenSSL c_rehash was giving me an error:

$ c_rehash
c_rehash: rehashing skipped ('openssl' program not available)

Pretty odd, since just typing openssl on the CLI clearly indicated that it was present.

Debuggin’ some Perl code

Nothing too fruitful was turning up on Google for this (the original program source was, though :P) so I dug into the program source (Perl) and found this bit at the top:

my $openssl;

my $dir = "/usr/lib/ssl";

if(defined $ENV{OPENSSL}) {
    $openssl = $ENV{OPENSSL};
} else {
    $openssl = "openssl";
    $ENV{OPENSSL} = $openssl;
}

$ENV{PATH} .= ":$dir/bin";

if(! -x $openssl) {
    my $found = 0;
    foreach (split /:/, $ENV{PATH}) {
        if(-x "$_/$openssl") {
            $found = 1;
            last;
        }    
    }
    if($found == 0) {
        print STDERR "c_rehash: rehashing skipped ('openssl' program not available)\n";
        exit 0;
    }
}

Sprinkling some liberal debugging statements into that yielded me the information that c_rehash was finding the relevant directories (and consequently the openssl binary) but the file wasn’t showing up as executable. Some Googling turned up stuff like this, which made me wonder…

If this solution would work

$ which openssl
/cygdrive/c/Program Files (x86)/Git/bin/openssl
$ chmod +x /cygdrive/c/Program\ Files\ \(x86\)/Git/bin/openssl

It did! You have to run Cygwin as administrator to have the proper permissions though to change those file permissions though.

c_rehash then went through without a hitch, Which finally allowed git clone to work.

Conclusion

Whew! That was exhausting. Time to do some programming to unwind :)

Until next time, stay sassy Internet.

  • Nathan