#! /bin/sh
exec perl -x $0 "$@"
#! perl

# Copyright (c) 2015 DeNA Co., Ltd.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to
# deal in the Software without restriction, including without limitation the
# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
# sell copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.

use strict;
use warnings;
use File::Temp qw(tempdir);
use Getopt::Long;

# from sysexits.h
use constant EX_TEMPFAIL => 75;

my ($issuer_fn, $opt_help);
my $openssl_cmd = 'openssl';

GetOptions(
    "issuer=s"   => \$issuer_fn,
    "openssl=s", => \$openssl_cmd,
    help         => \$opt_help,
) or exit(1);
if ($opt_help) {
    print << "EOT";
Usage: $0 [<options>] <certificate-file>

Options:
  --issuer <file>  issuer certificate (if omitted, is extracted from the
                   certificate chain)
  --openssl <cmd>  openssl command to use (default: "openssl")
  --help           prints this help

The command issues an OCSP request for given server certificate, verifies the
response and prints the resulting DER.

The command exits 0 if successful, or 75 (EX_TEMPFAIL) on temporary error.
Other exit codes may be returned in case of hard errors.

EOT
    exit(0);
}

die "no certificate file\n"
    if @ARGV == 0;
my $cert_fn = shift @ARGV;

my $tempdir = tempdir(CLEANUP => 1);

my $openssl_version = run_openssl("version");
chomp $openssl_version;
print STDERR "fetch-ocsp-response (using $openssl_version)\n";

# obtain ocsp uri
my $ocsp_uri = run_openssl("x509 -in $cert_fn -noout -ocsp_uri");
chomp $ocsp_uri;
die "failed to extract ocsp URI from $cert_fn\n"
    if $ocsp_uri !~ m{^https?://};
my($ocsp_host) = $ocsp_uri =~ m{^https?://([^/:]+)};

# save issuer certificate
if (! defined $issuer_fn) {
    my $chain = read_file($cert_fn);
    $chain =~ m{-----END CERTIFICATE-----.*?(-----BEGIN CERTIFICATE-----.*?-----END CERTIFICATE-----)}s
        or die "--issuer option was not used, and failed to extract issuer certificate from the certificate\n";
    $issuer_fn = "$tempdir/issuer.crt";
    write_file($issuer_fn, "$1\n");
}

# obtain response (without verification)
print STDERR "sending OCSP request to $ocsp_uri\n";
my $resp = run_openssl(
    "ocsp -issuer $issuer_fn -cert $cert_fn -url $ocsp_uri"
    . ($openssl_version =~ /^OpenSSL 1\./is ? " -header Host $ocsp_host" : "")
    . " -noverify -respout $tempdir/resp.der " . join(' ', @ARGV),
    1,
);
print STDERR $resp;

# verify the response
print STDERR "verifying the response signature\n";
my $success;
for my $args (
    # try from exotic options
    "-VAfile $issuer_fn",                               # for comodo
    "-partial_chain -trusted_first -CAfile $issuer_fn", # these options are only available in OpenSSL >= 1.0.2
    "-CAfile $issuer_fn",                               # for OpenSSL <= 1.0.1
) {
    if (system("$openssl_cmd ocsp -respin $tempdir/resp.der $args > $tempdir/verify.out 2>&1") == 0) {
        print STDERR "verify OK (used: $args)\n";
        $success = 1;
        last;
    }
}
if (! $success) {
    print STDERR read_file("$tempdir/verify.out");
    tempfail("failed to verify the response\n");
}

# success
print read_file("$tempdir/resp.der");
exit 0;

sub run_openssl {
    my ($args, $tempfail) = @_;
    open my $fh, "-|", "$openssl_cmd $args"
        or die "failed to invoke $openssl_cmd:$!";
    my $resp = do { local $/; <$fh> };
    close $fh
        or ($tempfail ? \&tempfail : \&die)->("OpenSSL exitted abnormally: $openssl_cmd $args:$!");
    $resp;
}

sub read_file {
    my $fn = shift;
    open my $fh, "<", $fn
        or die "failed to open file:$fn:$!";
    local $/;
    <$fh>;
}

sub write_file {
    my ($fn, $data) = @_;
    open my $fh, ">", $fn
        or die "failed to open file:$fn:$!";
    print $fh $data;
    close $fh;
}

sub tempfail {
    print STDERR @_;
    exit EX_TEMPFAIL;
}