After installing this thread's version (http://www.perlmonks.org/?node_id=1096884) of io/sock/ssl (https://github.com/noxxi/p5-io-socket-ssl), I'm still getting the same error "DEBUG: .../IO/Socket/SSL.pm:1483: local error: Could not retrieve peer certificate". I'm attempting to retrieve the browsers certificate data. This is for a smart card project where users are identified by their certificates, specifically their subjectAltName.

use strict;
use warnings;
use IO::Socket::SSL qw/debug4/;

my $addr = "\0\0\0\0:1235";
my $key_file = './certs/key.pem';
my $cert_file = './certs/certificate.pem';

my $ioclass = IO::Socket::SSL->can_ipv6 || 'IO::Socket::INET';
my $server = $ioclass->new(
    Listen => 5,
    LocalAddr => $addr,
    Reuse => 1,
) or die "failed to create SSL server at $addr: $!";

my $ctx = IO::Socket::SSL::SSL_Context->new(
    SSL_server => 1,
    SSL_cert_file => $cert_file,
    SSL_key_file  => $key_file,
    SSL_verify_mode => 0
) or die "cannot create context: $SSL_ERROR";

while (1) {
    warn "waiting for next connection.\n";
    my $cl = $server->accept or do {
    warn "failed to accept: $!\n";
    next;
    };

    IO::Socket::SSL->start_SSL($cl, SSL_server => 1, SSL_reuse_ctx => 
+$ctx) or do {
    warn "ssl handshake failed: $SSL_ERROR\n";
    next;
    };

    if ( $cl->peer_certificate ) {
    warn "new SSL connection with client certificate\n".
        "\tsubject=".$cl->peer_certificate('subject')."\n".
        "\tissuer=".$cl->peer_certificate('issuer')."\n"
    } else {
    warn "new SSL connection without client certificate\n"
    }

    print $cl "connected with cipher=".$cl->get_cipher." version=".$cl
+->get_sslversion."\n";
}
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