Refactoring to use the account key manager.

1 files changed, 679 insertions, 278 deletions

diff --git a/letsencrypt b/letsencrypt
index b6235cf..23659d5 100755
--- a/letsencrypt
+++ b/letsencrypt
@@ -1,8 +1,8 @@
-#!/bin/bash
+#!/usr/bin/perl -T
 
 #----------------------------------------------------------------------
-# Tiny Let's Encrypt ACME client
-# Copyright © 2015 Guilhem Moulin <guilhem@fripost.org>
+# Let's Encrypt ACME client
+# Copyright © 2016 Guilhem Moulin <guilhem@fripost.org>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -18,286 +18,687 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #----------------------------------------------------------------------
 
-set -ue
-set -o pipefail
-PATH=/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
-NAME=$(basename $0)
-
-WWW_USER=www-data
-ACME_WEBSERVER=/usr/lib/letsencrypt-tiny/webserver
-ACME_CLIENT=/usr/lib/letsencrypt-tiny/client
-CAfile=/usr/share/letsencrypt-tiny/lets-encrypt-x1-cross-signed.pem
-
-declare COMMAND ACCOUNTKEY
-declare -l GENKEY
-declare RUNAS QUIET= DEBUG=
-
-declare SRVCRT= CHAIN CSR SRVKEY
-declare -i MIN_AGE=0
-declare -l HASH=
-declare SUBJECT=/
-declare SAN=
-# https://security.stackexchange.com/questions/24106/which-key-usages-are-required-by-each-key-exchange-method
-declare KEYUSAGE='digitalSignature, keyEncipherment, keyCertSign'
-declare -a NOTIFY=()
-
-usage() {
-    local msg="${1:-}"
-    if [ "$msg" ]; then
-        echo "$NAME: $msg" >&2
-        echo "Try '$NAME --help' or consult the manpage for more information." >&2
-        exit 1
-    fi
-    cat <<- EOF
-		Usage: $NAME [OPTIONS] new-reg ACCOUNTKEY [EMAIL ..]
-		  or: $NAME [OPTIONS] new-cert ACCOUNTKEY --output=CERT {--csr=CSR | CSR Options }
-		  or: $NAME [OPTIONS] revoke-cert ACCOUNTKEY CERT [CERT ..]
-		Consult the manpage for more information.
-	EOF
-    exit 0
+use strict;
+use warnings;
+
+our $VERSION = '0.0.1';
+my $NAME = 'letsencrypt';
+
+use Errno qw/EADDRINUSE EINTR/;
+use Fcntl qw/F_GETFD F_SETFD FD_CLOEXEC SEEK_SET/;
+use File::Temp ();
+use Getopt::Long qw/:config posix_default no_ignore_case gnu_getopt auto_version/;
+use List::Util 'first';
+use POSIX ();
+use Socket qw/PF_INET PF_INET6 PF_UNIX INADDR_ANY IN6ADDR_ANY
+              SOCK_STREAM SOL_SOCKET SO_REUSEADDR SHUT_RDWR/;
+
+use Config::Tiny ();
+use Net::SSLeay ();
+
+# Clean up PATH
+$ENV{PATH} = join ':', qw{/usr/bin /bin};
+delete @ENV{qw/IFS CDPATH ENV BASH_ENV/};
+
+my ($COMMAND, %OPTS, $CONFFILE, $CONFIG, @CLEANUP);
+$SIG{$_} = sub() { exit 1 } foreach qw/INT TERM/; # run the END block upon SIGINT/SIGTERM
+
+
+#############################################################################
+# Parse and validate configuration
+#
+sub usage(;$$) {
+    my $rv = shift // 0;
+    if ($rv) {
+        my $msg = shift;
+        print STDERR $msg."\n" if defined $msg;
+        print STDERR "Try '$NAME --help' or consult the manpage for more information.\n";
+    }
+    else {
+        print STDERR "Usage: $NAME [--config=FILE] [--socket=PATH] [OPTIONS] COMMAND [ARGUMENT ..]\n"
+                    ."Consult the manpage for more information.\n";
+    }
+    exit $rv;
+}
+usage(1) unless GetOptions(\%OPTS, qw/config=s config-certs=s socket=s agreement-uri=s debug help|h/);
+usage(0) if $OPTS{help};
+
+$COMMAND = shift(@ARGV) // usage(1, "Missing command");
+$COMMAND = $COMMAND =~ /\A(new-reg|reg=\p{Print}*|new-cert|revoke-cert)\z/ ? $1
+         : usage(1, "Invalid command: $COMMAND"); # validate and untaint $COMMAND
+@ARGV = map { /\A(\p{Print}*)\z/ ? $1 : die } @ARGV; # untaint @ARGV
+
+do {
+    my $conffile = $OPTS{config} // first { -f $_ }
+        ( "./$NAME.conf"
+        , ($ENV{XDG_CONFIG_HOME} // "$ENV{HOME}/.config")."/letsencrypt-tiny/$NAME.conf"
+        , "/etc/letsencrypt-tiny/$NAME.conf"
+        );
+    die "Error: Can't find configuration file\n" unless defined $conffile;
+    print STDERR "Using configuration file: $conffile\n" if $OPTS{debug};
+    open $CONFFILE, '<', $conffile or die "Can't open $conffile: $!\n";
+    my $conf = do { local $/ = undef, <$CONFFILE> };
+    # don't close $CONFFILE so we can pass it to the client
+
+    my $h = Config::Tiny::->read_string($conf) or die Config::Tiny::->errstr()."\n";
+    my $defaults = delete $h->{_} // {};
+    my %valid = (
+        client => {
+            socket  => (defined $ENV{XDG_RUNTIME_DIR} ? "$ENV{XDG_RUNTIME_DIR}/S.letsencrypt" : undef),
+            user    => 'nobody',
+            group   => 'nogroup',
+            command => '/usr/lib/letsencrypt-tiny/client',
+            # the rest is for the ACME client
+            map {$_ => undef} qw/server timeout SSL_verify SSL_version SSL_cipher_list/
+        },
+        webserver => {
+            listen                => ':80',
+            'challenge-directory' => '/var/www/acme-challenge',
+            user                  => 'www-data',
+            group                 => 'www-data',
+            command               => '/usr/lib/letsencrypt-tiny/webserver',
+            iptables              => 'Yes'
+
+        }
+    );
+    foreach my $s (keys %valid) {
+        my $h = delete $h->{$s} // {};
+        my %v = map { $_ => delete $h->{$_} // $valid{$s}->{$_} } keys %{$valid{$s}};
+        die "Unknown option(s) in [$s]: ".join(', ', keys %$h)."\n" if %$h;
+        $h->{$_} //= $defaults->{$_} foreach keys %$defaults;
+        $CONFIG->{$s} = \%v;
+    }
+    die "Invalid section(s): ".join(', ', keys %$h)."\n" if %$h;
+    $CONFIG->{_} = $defaults;
+};
+
+# Regular expressions for domain validation
+my $RE_LABEL  = qr/[0-9a-z](?:[0-9a-z\x2D]{0,61}[0-9a-z])?/aai;
+my $RE_DOMAIN = qr/$RE_LABEL(?:\.$RE_LABEL)+/;
+
+
+#############################################################################
+# Generate a Certificate Signing Request (in DER format)
+#
+sub gen_csr(%) {
+    my %args = @_;
+    return unless defined $args{'certificate-key'} and defined $args{subject};
+    return if defined $args{hash} and !grep { $args{hash} eq $_ } qw/md5 rmd160 sha1 sha224 sha256 sha384 sha512/;
+
+    my $config = File::Temp::->new(SUFFIX => '.conf', TMPDIR => 1) // die;
+    $config->print(
+        "[ req ]\n",
+        "distinguished_name = req_distinguished_name\n",
+        "req_extensions     = v3_req\n",
+
+        "[ req_distinguished_name ]\n",
+
+        "[ v3_req ]\n",
+        # XXX Golang errors on extensions marked critical
+        # https://github.com/letsencrypt/boulder/issues/565
+        #"basicConstraints     = critical, CA:FALSE\n",
+        "basicConstraints     = CA:FALSE\n",
+        "subjectKeyIdentifier = hash\n"
+    );
+    #$config->print("keyUsage = critical, $args{keyUsage}\n")   if defined $args{keyUsage};
+    $config->print("keyUsage = $args{keyUsage}\n")             if defined $args{keyUsage};
+    $config->print("subjectAltName = $args{subjectAltName}\n") if defined $args{subjectAltName};
+    $config->close() or die "Can't close: $!";
+
+    my @args = (qw/-new -batch -key/, $args{'certificate-key'});
+    push @args, "-$args{hash}" if defined $args{hash};
+    push @args, '-subj', $args{subject}, '-config', $config->filename(), qw/-reqexts v3_req/;
+
+    open my $fh, '-|', qw/openssl req -outform DER/, @args or die "fork: $!";
+    my $csr = do { local $/ = undef; <$fh> };
+    close $fh or $! ? die "Can't close: $!" : return;
+
+    if ($OPTS{debug}) {
+        # print out the CSR in text form
+        pipe my $rd, my $wd or die "pipe: $!";
+        my $pid = fork // die "fork: $!";
+        unless ($pid) {
+            open STDIN,  '<&', $rd      or die "Can't dup: $!";
+            open STDOUT, '>&', \*STDERR or die "Can't dup: $!";
+            exec qw/openssl req -noout -text -inform DER/ or die;
+        }
+        $rd->close() or die "Can't close: $!";
+        $wd->print($csr);
+        $wd->close() or die "Can't close: $!";
+
+        waitpid $pid => 0;
+        die $? if $? > 0;
+    }
+
+    return $csr;
+}
+
+
+#############################################################################
+# Get the timestamp of the given cert's expiration date.
+# Internally the expiration date is stored as a RFC3339 string (such as
+# yyyy-mm-ddThh:mm:ssZ); we convert it to a timestamp manually.
+#
+sub x509_enddate($) {
+    my $filename = shift;
+    my ($bio, $x509, $time, $dt);
+
+    $bio  = Net::SSLeay::BIO_new_file($filename, 'r');
+    $x509 = Net::SSLeay::PEM_read_bio_X509($bio)        if defined $bio;
+    $time = Net::SSLeay::X509_get_notAfter($x509)       if defined $x509;
+    $dt   = Net::SSLeay::P_ASN1_TIME_get_isotime($time) if defined $time;
+
+    my $t;
+    if (defined $dt and $dt =~ s/\A(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})//) {
+        # RFC3339 datetime strings; assume epoch is on January 1 of $epoch_year
+        my ($y, $m, $d, $h, $min, $s) = ($1, $2, $3, $4, $5, $6);
+        my (undef,undef,undef,undef,undef,$epoch_year,undef,undef,undef) = gmtime(0);
+        $t = 0;
+        foreach (($epoch_year+1900) .. $y-1) {
+            $t += 365*86400;
+            $t += 86400 if ($_ % 4 == 0 and $_ % 100 != 0) or ($_ % 400 == 0); # leap
+        }
+
+        if ($m > 1) {
+            my @m = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
+            $m[1]++ if ($y % 4 == 0 and $y % 100 != 0) or ($y % 400 == 0); # leap
+            $t += 86400*$m[$_] for (0 .. $m-2);
+        }
+
+        $t += 86400*($d-1);
+        $t += $s + 60*($min + 60*$h);
+
+        $dt =~ s/\A\.(\d{1,9})\d*//; # ignore nanosecs
+
+        if ($dt =~ /\A([+-])(\d{2}):(\d{2})\z/) {
+            my $tz = 60*($3 + 60*$2);
+            $t = $1 eq '-' ? ($t+$tz) : ($t-$tz);
+        }
+    }
+
+    Net::SSLeay::X509_free($x509) if defined $x509;
+    Net::SSLeay::BIO_free($bio)   if defined $bio;
+    return $t;
+}
+
+
+#############################################################################
+# Drop privileges and chdir afterwards
+#
+sub drop_privileges($$$) {
+    my ($user, $group, $dir) = @_;
+
+    # set effective and real gid; also set the list of supplementary gids to that single gid
+    if ($group ne '') {
+        my $gid = getgrnam($group) // die "Can't getgrnam($group): $!";
+        $) = "$gid $gid";
+        die "Can't setgroups: $!" if $@;
+        POSIX::setgid($gid) or die "Can't setgid: $!";
+        die "Couldn't setgid/setguid" unless $( eq "$gid $gid" and $) eq "$gid $gid"; # safety check
+    }
+
+    # set effective and real uid
+    if ($user ne '') {
+        my $uid = getpwnam($user) // die "Can't getpwnam($user): $!";
+        POSIX::setuid($uid) or die "Can't setuid: $!";
+        die "Couldn't setuid/seteuid" unless $< == $uid and $> == $uid; # safety check
+    }
+
+    chdir $dir or die "Can't chdir to $dir: $!";
+}
+
+
+#############################################################################
+# Ensure the FD_CLOEXEC bit is $set on $fd
+#
+sub set_FD_CLOEXEC($$) {
+    my ($fd, $set) = @_;
+    my $flags = fcntl($fd, F_GETFD, 0) or die "Can't fcntl F_GETFD: $!";
+    my $flags2 = $set ? ($flags | FD_CLOEXEC) : ($flags & ~FD_CLOEXEC);
+    return if $flags == $flags2;
+    fcntl($fd, F_SETFD, $flags2) or die "Can't fcntl F_SETFD: $!";
+}
+
+
+#############################################################################
+# Try to spawn a webserver to serve ACME challenges, and return the
+# temporary challenge directory.
+# If a webserver is already listening, symlink the 'challenge-directory'
+# configuration option to the temporary challenge directory.
+# Otherwise, bind(2) a socket, pass its fileno to the webserver
+# component, and optionally install iptables rules.
+#
+sub spawn_webserver() {
+    # create a temporary directory; give write access to the ACME client
+    # and read access to the webserver
+    my $tmpdir = File::Temp::->newdir(CLEANUP => 1, TMPDIR => 1) // die;
+    chmod 0755, $tmpdir or die "Can't chmod: $!";
+    if ((my $username = $CONFIG->{client}->{user}) ne '') {
+        my $uid = getpwnam($username) // die "Can't getgrnam($username): $!";
+        chown($uid, -1, $tmpdir) or die "Can't chown: $!";
+    }
+
+    my $conf = $CONFIG->{webserver};
+    my ($fam, $addr, $port) = (PF_INET, $conf->{listen}, 80);
+    $port = $1 if $addr =~ s/:(\d+)$//;
+    $addr = Socket::inet_ntop(PF_INET, INADDR_ANY) if $addr eq '';
+    $fam = PF_INET6 if $addr =~ s/^\[(.+)\]$/$1/;
+
+    my $proto = getprotobyname("tcp") // die;
+    socket(my $srv, $fam, SOCK_STREAM, $proto) or die "socket: $!";
+    setsockopt($srv, SOL_SOCKET, SO_REUSEADDR, pack("l", 1)) or die "setsockopt: $!";
+    $addr = Socket::inet_pton($fam, $addr) // die "Invalid address $conf->{listen}\n";
+    my $sockaddr = $fam == PF_INET  ? Socket::pack_sockaddr_in($port,  $addr)
+                 : $fam == PF_INET6 ? Socket::pack_sockaddr_in6($port, $addr)
+                 : die;
+
+    # try to bind aginst the specified address:port
+    bind($srv, $sockaddr) or do {
+        die "Can't bind to $conf->{listen}: $!" if $! != EADDRINUSE;
+        print STDERR "[$$] Using existing webserver on $conf->{listen}\n" if $OPTS{debug};
+        my $dir = $conf->{'challenge-directory'};
+        symlink $tmpdir, $dir or die "Can't symlink $dir -> $tmpdir: $!";
+        push @CLEANUP, sub() {
+            print STDERR "Unlinking $dir\n" if $OPTS{debug};
+            unlink $dir or warn "Warning: Can't unlink $dir: $!";
+        };
+        return $tmpdir;
+    };
+    listen($srv, 5) or die "listen: $!";
+
+    # spawn the webserver component
+    my $pid = fork() // "fork: $!";
+    unless ($pid) {
+        drop_privileges($conf->{user}, $conf->{group}, $tmpdir);
+        set_FD_CLOEXEC($srv, 0);
+        $ENV{DEBUG} = $OPTS{debug};
+        # use execve(2) rather than a Perl pseudo-process to ensure that
+        # the child doesn't have access to the parent's memory
+        exec $conf->{command}, fileno($srv) or die;
+    }
+
+    print STDERR "[$$] Forking ACME webserver, child PID $pid\n" if $OPTS{debug};
+    set_FD_CLOEXEC($srv, 1);
+    push @CLEANUP, sub() {
+        print STDERR "[$$] Shutting down ACME webserver\n" if $OPTS{debug};
+        shutdown($srv, SHUT_RDWR) or warn "shutdown: $!";
+        kill 15 => $pid;
+        waitpid $pid => 0;
+    };
+
+    return $tmpdir if lc ($conf->{iptables} // 'Yes') eq 'no';
+
+    # install iptables
+    my $iptables_bin = $fam == PF_INET ? 'iptables' : $fam == PF_INET6 ? 'ip6tables' : die;
+    my $iptables_tmp = File::Temp::->new(TMPDIR => 1) // die;
+    set_FD_CLOEXEC($iptables_tmp, 1);
+
+    my $pid2 = fork() // die "fork: $!";
+    unless ($pid2) {
+        open STDIN,  '<',  '/dev/null'   or die "Can't open /dev/null: $!";
+        open STDOUT, '>&', $iptables_tmp or die "Can't dup: $!";
+        $| = 1; # turn off buffering for STDOUT
+        exec "/sbin/$iptables_bin-save", "-c" or die;
+    }
+    waitpid $pid2 => 0;
+    die "Error: /sbin/$iptables_bin-save exited with value ".($? >> 8) if $? > 0;
+
+    # seek back to the begining, as we'll restore directly from the
+    # handle and not from the file.  XXX if there was a way in Perl to
+    # use open(2) with the O_TMPFILE flag we would use that to avoid
+    # creating a file to start with
+    seek($iptables_tmp, SEEK_SET, 0) or die "Can't seek: $!";
+
+    push @CLEANUP, sub() {
+        print STDERR "[$$] Restoring iptables\n" if $OPTS{debug};
+        my $pid2 = fork() // die "fork: $!";
+        unless ($pid2) {
+            open STDIN, '<&', $iptables_tmp or die "Can't dup: $!";
+            open STDOUT, '>', '/dev/null'   or die "Can't open /dev/null: $!";
+            exec "/sbin/$iptables_bin-restore", "-c" or die;
+        }
+        waitpid $pid2 => 0;
+        warn "Warning: /sbin/$iptables_bin-restore exited with value ".($? >> 8) if $? > 0;
+    };
+
+    # it's safe to install the new iptables to open $port now that the
+    # restore hook is in place
+    my $mask = $fam == PF_INET  ? ($addr eq INADDR_ANY  ? '0' : '32')
+             : $fam == PF_INET6 ? ($addr eq IN6ADDR_ANY ? '0' : '128')
+             : die;
+    my $dest = Socket::inet_ntop($fam, $addr) .'/'. $mask;
+
+    system ("/sbin/$iptables_bin", qw/-I INPUT  -p tcp -m tcp -m state/,
+            '-d', $dest, '--dport', $port,
+            '--state', 'NEW,ESTABLISHED', '-j', 'ACCEPT') == 0 or die;
+    system ("/sbin/$iptables_bin", qw/-I OUTPUT -p tcp -m tcp -m state/,
+            '-s', $dest, '--sport', $port,
+            '--state',     'ESTABLISHED', '-j', 'ACCEPT') == 0 or die;
+
+    return $tmpdir;
+}
+
+
+#############################################################################
+# Spawn the client component, and wait for it to return.
+# If $args->{in} is defined, the data is written to the client's STDIN.
+# If $args->{out} is defined, its value is set to client's STDOUT data.
+#
+sub acme_client($@) {
+    my $args = shift;
+    my @args = @_;
+
+    my @stat;
+    my $conf = $CONFIG->{client};
+    my $sockname = $OPTS{socket} // $conf->{socket} // die "Missing socket option\n";
+    $sockname = $sockname =~ /\A(\p{Print}+)\z/ ? $1 : die "Invalid socket name\n"; # untaint $sockname
+
+    # ensure we're the only user with write access to the parent dir
+    my $dirname = $sockname =~ s/[^\/]+$//r;
+    @stat = stat($dirname) or die "Can't stat $dirname: $!";
+    die "Error: insecure permissions on $dirname\n" if ($stat[2] & 0022) != 0;
+
+    # ensure we're the only user with read/write access to the socket
+    @stat = stat($sockname) or die "Can't stat $sockname: $!  (Is letsencrypt-accountd running?)\n";
+    die "Error: insecure permissions on $sockname\n" if ($stat[2] & 0066) != 0;
+
+    # connect(2) to the socket
+    socket(my $client, PF_UNIX, SOCK_STREAM, 0) or die "socket: $!";
+    my $sockaddr = Socket::sockaddr_un($sockname) // die "Invalid address $sockname\n";
+    until (connect($client, $sockaddr)) {
+        next if $! == EINTR; # try again if connect(2) was interrupted by a signal
+        die "connect: $!";
+    }
+
+    my @fileno = map { fileno($_) =~ /^(\d+)$/ ? $1 : die } ($CONFFILE, $client); # untaint fileno
+    spawn({%$args{qw/in out/}, child => sub() {
+        drop_privileges($conf->{user}, $conf->{group}, $args->{chdir} // '/');
+        set_FD_CLOEXEC($_, 0) foreach ($CONFFILE, $client);
+        seek($CONFFILE, SEEK_SET, 0) or die "Can't seek: $!";
+        $ENV{DEBUG} = $OPTS{debug};
+    }}, $conf->{command}, $COMMAND, @fileno, @args);
+}
+
+sub spawn($@) {
+    my $args = shift;
+    my @exec = @_;
+
+    # create communication pipes if needed
+    my ($in_rd, $in_wd, $out_rd, $out_wd);
+    if (defined $args->{in}) {
+        pipe $in_rd, $in_wd or die "pipe: $!";
+    }
+    if (defined $args->{out}) {
+        pipe $out_rd, $out_wd or die "pipe: $!";
+    }
+
+    my $pid = fork() // "fork: $!";
+    unless ($pid) {
+        # child
+        $args->{child}->() if defined $args->{child};
+        if (defined $args->{in}) {
+            close $in_wd or die "Can't close: $!";
+            open STDIN, '<&', $in_rd or die "Can't dup: $!";
+        } else {
+            open STDIN, '<', '/dev/null' or die "Can't open /dev/null: $!";
+        }
+        if (defined $args->{out}) {
+            close $out_rd or die "Can't close: $!";
+            open STDOUT, '>&', $out_wd or die "Can't dup: $!";
+        } else {
+            open STDOUT, '>', '/dev/null' or die "Can't open /dev/null: $!";
+        }
+        # use execve(2) rather than a Perl pseudo-process to ensure that
+        # the child doesn't have access to the parent's memory
+        exec { $exec[0] } @exec or die;
+    }
+    push @CLEANUP, sub() {
+        kill 15 => $pid;
+        waitpid $pid => 0;
+    };
+
+    # parent
+    print STDERR "[$$] Forking $exec[0], child PID $pid\n" if $OPTS{debug};
+    if (defined $args->{in}) {
+        $in_rd->close() or die "Can't close: $!";
+        $in_wd->print($args->{in});
+        $in_wd->close() or die "Can't close: $!";
+    }
+    if (defined $args->{out}) {
+        $out_wd->close() or die "Can't close: $!";
+        ${$args->{out}} = do { local $/ = undef; $out_rd->getline() };
+        $out_rd->close() or die "Can't close: $!";
+    }
+    waitpid $pid => 0;
+    pop @CLEANUP;
+    undef ${$args->{out}} if defined $args->{out} and $? > 0;
+    return $? > 255 ? ($? >> 8) : $? > 0 ? 1 : 0;
+}
+
+
+#############################################################################
+# Install the certificate
+#
+sub install_cert($$@) {
+    my $filename = shift;
+    my $x509 = shift;
+
+    open my $fh, '>', $filename or die "Can't open $filename: $!";
+    print $fh $x509;
+    foreach (@_) { # append the chain
+        open my $fh2, '<', $_ or die "Can't open $_: $!";
+        my $ca = do { local $/ = undef; $fh2->getline() };
+        print $fh $ca;
+        close $fh2 or die "Can't close: $!";
+    }
+    close $fh or die "Can't close: $!";
 }
 
-# Generate a key pair with mode 0600
-genkey() {
-    local key="$1" genkey= bits=
-    case "$GENKEY" in
-        rsa) genkey=genrsa;;
-        rsa:*) genkey=genrsa; bits=${GENKEY#*:};;
-        *) echo "Error: invalid key type ${GENKEY%%:*}" >&2; exit 1;;
-    esac
-    install --mode=0600 /dev/null "$key" # atomic creation with mode 0600
-    openssl "$genkey" $bits >"$key"
+
+#############################################################################
+# new-reg [--agreement-uri=URI] [CONTACT ..]
+# reg=URI [--agreement-uri=URI] [CONTACT ..]
+#
+if ($COMMAND eq 'new-reg' or $COMMAND =~ /^reg=/) {
+    die "Invalid registration URI (use the 'new-reg' command to determine the URI)\n"
+        if $COMMAND eq 'reg=';
+    $OPTS{'agreement-uri'} = $OPTS{'agreement-uri'} =~ /\A(\p{Print}+)\z/ ? $1
+                           : die "Invalid value for --agreement-uri\n"
+        if defined $OPTS{'agreement-uri'};
+
+    unshift @ARGV, ($OPTS{'agreement-uri'} // '');
+    exit acme_client({}, @ARGV);
+}
+
+
+#############################################################################
+# new-cert [SECTION ..]
+#   TODO: renewal without the account key, see
+#         https://github.com/letsencrypt/acme-spec/pull/168
+#
+elsif ($COMMAND eq 'new-cert') {
+    my $conf;
+    do {
+        my $conffile = $OPTS{'config-certs'} // $CONFIG->{_}->{'config-certs'} // first { -f $_ }
+            ( "./$NAME-certs.conf"
+            , ($ENV{XDG_CONFIG_HOME} // "$ENV{HOME}/.config")."/letsencrypt-tiny/$NAME-certs.conf"
+            , "/etc/letsencrypt-tiny/$NAME-certs.conf"
+            );
+        die "Error: Can't find certificate configuration file\n" unless defined $conffile;
+        my $h = Config::Tiny::->read($conffile) or die Config::Tiny::->errstr()."\n";
+        my $defaults = delete $h->{_} // {};
+        my @valid = qw/certificate certificate-chain certificate-key min-days CAfile
+                       hash keyUsage subject subjectAltName chown chmod notify/;
+        foreach my $s (keys %$h) {
+            $conf->{$s} = { map { $_ => delete $h->{$s}->{$_} } @valid };
+            die "Unknown option(s) in [$s]: ".join(', ', keys %{$h->{$s}})."\n" if %{$h->{$s}};
+            $conf->{$s}->{$_} //= $defaults->{$_} foreach keys %$defaults;
+        }
+    };
+
+    my $challenge_dir;
+    my $rv = 0;
+    foreach my $s (@ARGV ? @ARGV : keys %$conf) {
+        my $conf = $conf->{$s} // do {
+            print STDERR "Warning: No such section $s, skipping\n";
+            $rv = 1;
+            next;
+        };
+
+        my $certtype = first { defined $conf->{$_} } qw/certificate certificate-chain/;
+        unless (defined $certtype) {
+            print STDERR "[$s] Warning: Missing 'certificate' and 'certificate-chain', skipping\n";
+            $rv = 1;
+            next;
+        }
+
+        # skip certificates that expire at least $conf->{'min-days'} days in the future
+        if (-f $conf->{$certtype} and defined (my $t = x509_enddate($conf->{$certtype}))) {
+            my $d = $conf->{'min-days'} // 10;
+            if ($d > 0 and $t - time > $d*86400) {
+                my $d = POSIX::strftime('%Y-%m-%d %H:%M:%S UTC', gmtime($t));
+                print STDERR "[$s] Valid until $d, skipping\n";
+                next;
+            }
+        }
+
+        # generate the CSR
+        my $csr = gen_csr(%$conf{qw/certificate-key subject subjectAltName keyUsage hash/}) // do {
+            print STDERR "[$s] Warning: Couldn't generate CSR, skipping\n";
+            $rv = 1;
+            next;
+        };
+
+        # spawn the webserver if not done already
+        $challenge_dir //= spawn_webserver();
+
+        # list all authorization domains to request
+        my @authz;
+        push @authz, $1 if defined $conf->{subject} =~ /\A.*\/CN=($RE_DOMAIN)\z/o;
+        if (defined $conf->{subjectAltName}) {
+            foreach my $d (split /,/, $conf->{subjectAltName}) {
+                next unless $d =~ s/\A\s*DNS://;
+                if ($d =~ /\A$RE_DOMAIN\z/o) {
+                    push @authz, $d unless grep {$_ eq $d} @authz;
+                } else {
+                    print STDERR "[$s] Warning: Ignoring invalid domain $d\n";
+                }
+            }
+        }
+
+        my ($x509, $csr_pubkey, $x509_pubkey);
+        print STDERR "[$s] Will request authorization for: ".join(", ", @authz), "\n" if $OPTS{debug};
+        if (acme_client({chdir => $challenge_dir, in => $csr, out => \$x509}, @authz)) {
+            print STDERR "[$s] Error: Couldn't issue X.509 certificate!\n";
+            $rv = 1;
+            next;
+        }
+
+        # extract pubkeys from CSR and cert, and ensure they match
+        spawn({in => $csr,  out => \$csr_pubkey }, qw/openssl req  -inform DER -noout -pubkey/);
+        spawn({in => $x509, out => \$x509_pubkey}, qw/openssl x509 -inform PEM -noout -pubkey/);
+        unless (defined $x509_pubkey and defined $csr_pubkey and $x509_pubkey eq $csr_pubkey) {
+            print STDERR "[$s] Error: Received bogus X.509 certificate from ACME server!\n";
+            $rv = 1;
+            next;
+        };
+
+        # verify certificate validity against the CA
+        $conf->{CAfile} //= '/usr/share/letsencrypt-tiny/lets-encrypt-x1-cross-signed.pem';
+        if ($conf->{CAfile} ne '' and spawn({in => $x509}, 'openssl', 'verify', '-CAfile', $conf->{CAfile},
+                                                                      qw/-purpose sslserver -x509_strict/)) {
+            print STDERR "[$s] Error: Received invalid X.509 certificate from ACME server!\n";
+            $rv = 1;
+            next;
+        }
+
+        # install certificate
+        if (defined $conf->{'certificate'}) {
+            print STDERR "Installing X.509 certificate $conf->{'certificate'}\n";
+            install_cert($conf->{'certificate'}, $x509);
+        }
+        if (defined $conf->{'certificate-chain'}) {
+            print STDERR "Installing X.509 certificate chain $conf->{'certificate-chain'}\n";
+            install_cert($conf->{'certificate-chain'}, $x509, $conf->{CAfile});
+        }
+
+        if (defined $conf->{chown}) {
+            my ($user, $group) = split /:/, $conf->{chown}, 2;
+            my $uid = getpwnam($user) // die "Can't getpwnam($user): $!";
+            my $gid = defined $group ? (getgrnam($group) // die "Can't getgrnam($group): $!") : -1;
+            foreach (grep defined, @$conf{qw/certificate certificate-chain/}) {
+                chown($uid, $gid, $_) or die "Can't chown: $!";
+            }
+        }
+        if (defined $conf->{chmod}) {
+            my $mode = oct($conf->{chmod}) // die;
+            foreach (grep defined, @$conf{qw/certificate certificate-chain/}) {
+                chmod($mode, $_) or die "Can't chown: $!";
+            }
+        }
+
+        my @certopts = join ',', qw/no_header no_version no_pubkey no_sigdump/;
+        open my $fh, '|-', qw/openssl x509 -noout -fingerprint -sha256 -text -certopt/, @certopts
+            or die "fork: $!";
+        print $fh $x509;
+        close $fh or die $! ?
+            "Can't close: $!" :
+            "Error: x509(1ssl) exited with value ".($? >> 8)."\n";
+
+        if (defined $conf->{notify}) {
+            print STDERR "Running notification command `$conf->{notify}`\n";
+            if (system($conf->{notify}) != 0) {
+                print STDERR "Warning: notification command exited with value ".($? >> 8)."\n";
+                $rv = 1;
+            }
+        }
+    }
+    undef $challenge_dir;
+    exit $rv;
 }
 
 
-# Parse options
-declare -a ARGV=()
-while [ $# -gt 0 ]; do
-    case "$1" in
-        --genkey) GENKEY=RSA;;
-        --genkey=*) GENKEY="${1#*=}";;
-        --runas=*) RUNAS="${1#*=}";;
-        --help|-\?) usage;;
-        --quiet|-q) QUIET=1;;
-        --debug) DEBUG=1;;
-
-        --output=*) SRVCRT="${1#*=}";;
-        --min-age=*) MIN_AGE="${1#*=}";;
-        --chain) CHAIN=;;
-        --chain=*) CHAIN="${1#*=}";;
-        --csr=*) CSR="${1#*=}";;
-        --key=*) SRVKEY="${1#*=}";;
-        --hash=*) HASH="${1#*=}";;
-        --subject=*) SUBJECT="${1#*=}";;
-        --san=*) SAN="${1#*=}";;
-        --keyusage=*) KEYUSAGE="${1#*=}";;
-        --notify=*) NOTIFY+=( "${1#*=}" );;
-
-        --) shift; ARGV+=( "$@" ); break ;;
-        -*) usage "unknown option '${1%%=*}'";;
-        *) if [ ${ACCOUNTKEY+x} ]; then
-               ARGV+=( "$1" )
-           else
-               [ ${COMMAND+x} ] && ACCOUNTKEY="$1" || COMMAND="$1"
-           fi
-    esac
-    shift
-done
-
-[ "${COMMAND:-}" ] || usage "missing command"
-[ "$COMMAND" = 'new-reg' -o "$COMMAND" = 'new-cert' -o "$COMMAND" = 'revoke-cert' ] ||
-    usage "invalid command $COMMAND"
-[ ${#ARGV[@]} -eq 0 -o "$COMMAND" = 'new-reg' -o "$COMMAND" = 'revoke-cert' ] ||
-    usage "invalid argument ${ARGV[0]}"
-
-[ "${ACCOUNTKEY:-}" ] || usage "missing account key"
-if ! [ -f "$ACCOUNTKEY" -a -s "$ACCOUNTKEY" ]; then
-    if [ "$COMMAND" = 'new-reg' -a "${GENKEY+x}" ]; then
-        genkey "$ACCOUNTKEY"
-    else
-        echo "Error: keyfile '$ACCOUNTKEY' does not exist." >&2
-        [[ ! "$COMMAND" =~ ^new- ]] || echo "Use 'new-reg --genkey' to generate and register an RSA key with mode 0600." >&2
-        exit 1
-    fi
-fi
-
-
-declare -a TMPFILES=()
-declare CHALLENGE_DIR IPTABLES_SAVE
-cleanup() {
-    set +e
-    [ ! ${IPTABLES_SAVE+x} ] || iptables-restore -c <"$IPTABLES_SAVE"
-    pkill -TERM -P $$
-    [ ${#TMPFILES[@]} -eq 0 ] || rm  -${DEBUG:+v}f "${TMPFILES[@]}"
-    [ ! ${CHALLENGE_DIR+x} ] || rm -${DEBUG:+v}rf "$CHALLENGE_DIR"
+#############################################################################
+# revoke-cert FILE [FILE ..]
+#
+elsif ($COMMAND eq 'revoke-cert') {
+    die "Nothing to revoke\n" unless @ARGV;
+    my $rv = 0;
+    foreach my $filename (@ARGV) {
+        print STDERR "Revoking $filename\n";
+
+        # conversion PEM -> DER
+        open my $fh, '-|', qw/openssl x509 -outform DER -in/, $filename or die "fork: $!";
+        my $der = do { local $/ = undef; <$fh> };
+        close $fh or die $! ?
+            "Can't close: $!" :
+            "Error: x509(1ssl) exited with value ".($? >> 8)."\n";
+
+        my @certopts = join ',', qw/no_header no_version no_pubkey no_sigdump no_extensions/;
+        open my $fh2, '|-', qw/openssl x509 -inform DER -noout -fingerprint -sha256 -text -certopt/, @certopts
+            or die "fork: $!";
+        print $fh2 $der;
+        close $fh2 or die $! ?
+            "Can't close: $!" :
+            "Error: x509(1ssl) exited with value ".($? >> 8)."\n";
+
+        if (acme_client({in => $der})) {
+            print STDERR "Warning: Couldn't revoke $filename\n";
+            $rv = 1;
+        }
+    }
+    exit $rv;
 }
-trap cleanup EXIT SIGINT
-
-
-# Extract the public part of the user key
-accountpub=$(mktemp --tmpdir XXXXXX.pub)
-TMPFILES+=( "$accountpub" )
-openssl pkey -pubout <"$ACCOUNTKEY" >"$accountpub"
-chmod 0644 "$accountpub"
-
-
-if [ "$COMMAND" = 'revoke-cert' ]; then
-    if [ ${#ARGV[@]} -eq 0 ]; then
-        echo "Error: Nothing to revoke" >&2
-        exit 1
-    fi
-elif [ "$COMMAND" = 'new-cert' ]; then
-    if [ ! "${SRVCRT:-}" ]; then
-        echo "Error: Missing --output" >&2
-        exit 1
-    fi
-    if [ -s "$SRVCRT" ] && [ $MIN_AGE -gt 0 ] && \
-         exp=$(openssl x509 -noout -enddate <"$SRVCRT" 2>/dev/null) && \
-         [ $(( $(date -d "${exp#*=}" +%s) - $(date +%s))) -gt $MIN_AGE ]; then
-        [ ! "$DEBUG" ] || echo "Expiration date ($(date -d"${exp#*=}")) is too far away, come back later." >&2
-        exit 0
-    fi
-
-    # Generate a Certificate Signing Request if need be
-    if [ ${CSR+x} ]; then
-        if [ -z "$CSR" -o ! -s "$CSR" ]; then
-            echo "Error: Missing Certificate Signing Request $CSR.  (One of --csr or --key must be set.)" >&2
-            exit 1
-        fi
-    else
-        CSR=$(mktemp --tmpdir XXXXXX.csr)
-        config=$(mktemp --tmpdir XXXXXX.cnf)
-        TMPFILES+=( "$CSR" "$config" )
-        chmod 0644 "$CSR"
-
-        if [ "$HASH" ]; then
-            case "$HASH" in
-                md5|rmd160|sha1|sha224|sha256|sha384|sha512) HASH="-$HASH";;
-                *) echo "Invalid digest algorithm: $HASH" >&2; exit 1;;
-            esac
-        fi
-        if [ ! "${SRVKEY:-}" ] || [ ! -s "$SRVKEY" ]; then
-            if [ "${SRVKEY:-}" -a "${GENKEY+x}" ]; then
-                genkey "$SRVKEY"
-            else
-                echo "Error: Missing private server key.  Use new-cert --genkey --key=... to generate" >&2
-                exit 1
-            fi
-        fi
-
-        [ ! "$DEBUG" ] || echo 'Generating Certificate Signing Request...' >&2
-        cat >"$config" <<- EOF
-			[ req ]
-			distinguished_name = req_distinguished_name
-			req_extensions     = v3_req
-
-			[ req_distinguished_name ]
-
-			[ v3_req ]
-			${SAN:+subjectAltName= $SAN}
-			# XXX Golang errors on extensions marked critical
-			# https://github.com/letsencrypt/boulder/issues/565
-			#basicConstraints     = critical, CA:FALSE
-			#keyUsage             = critical${KEYUSAGE:+, $KEYUSAGE}
-			basicConstraints     = CA:FALSE
-			keyUsage             = $KEYUSAGE
-			subjectKeyIdentifier = hash
-		EOF
-        openssl req -new -batch -key "$SRVKEY" $HASH -subj "$SUBJECT" -config "$config" -reqexts v3_req >"$CSR"
-    fi
-    [ ! "$DEBUG" ] || openssl req -noout -text <"$CSR"
-
-    CHALLENGE_DIR=$(mktemp --tmpdir -d acme-challenge.XXXXXX)
-    x509=$(mktemp --tmpdir XXXXXX.pem)
-    TMPFILES+=( "$x509" )
-
-    [ ! "${RUNAS:-}" ] || chown "$RUNAS" "$CHALLENGE_DIR" "$x509"
-    chgrp "$(id -g -- "$WWW_USER")" "$CHALLENGE_DIR"
-    chmod 0750 "$CHALLENGE_DIR"
-
-    # Make sure a webserver is configured to server ACME challenges
-    if nc -z 127.0.0.1 80; then
-        [ ! "$DEBUG" ] || echo "Using existing webserver" >&2
-        ln -${DEBUG:+v}Ts "$CHALLENGE_DIR" /var/www/acme-challenge
-        TMPFILES+=( "/var/www/acme-challenge" )
-    else
-        temp=$(mktemp --tmpdir)
-        TMPFILES+=( "$temp" )
-        iptables-save -c >"$temp"
-        IPTABLES_SAVE="$temp"
-        iptables -I INPUT  -p tcp -m tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
-        iptables -I OUTPUT -p tcp -m tcp --sport 80 -m state --state     ESTABLISHED -j ACCEPT
-        (
-            [ ! "$DEBUG" ] || echo "Starting ACME webserver in $CHALLENGE_DIR" >&2
-            cd "$CHALLENGE_DIR" || exit 1
-            # use the "su" otion rather than "setuid/setgid" since while setgid
-            # changes the primary group of the process, it doesn't drop other
-            # group related privileges
-            exec socat \
-                TCP-LISTEN:80,su="$WWW_USER",reuseaddr,fork,max-children=5 \
-                EXEC:"$ACME_WEBSERVER"
-        )&
-    fi
-
-    ARGV=( "$CSR" "$CHALLENGE_DIR" "$x509" )
-fi
-
-
-pipe=$(mktemp --tmpdir -u XXXXXX.fifo)
-mkfifo -m0600 "$pipe"
-TMPFILES+=( "$pipe" )
-
-# Wait for signing requests from the ACME slave
-acme_client() {
-    if [ "${RUNAS:-}" ]; then
-         sudo -u "$RUNAS" ${DEBUG:+DEBUG="$DEBUG"} -- $ACME_CLIENT "$@"
-    else
-        [ ${RUNAS+x} ] || echo "WARNING: Use --runas=USER to specify a user to drop permissions to." >&2
-        DEBUG="$DEBUG" $ACME_CLIENT "$@"
-    fi
+
+
+#############################################################################
+#
+else {
+    die "Unknown command $COMMAND"
 }
 
-acme_client "$COMMAND" "$accountpub" ${ARGV[0]+"${ARGV[@]}"} <"$pipe" |
-while read data; do
-    echo -n "$data" | openssl dgst -sha256 -sign "$ACCOUNTKEY" -hex | sed 's/.*=\s*//'
-done >"$pipe"
-
-if [ "$COMMAND" != 'new-cert' ]; then
-    [ "$QUIET" ] || echo OK
-else
-    # Ensure the cert's pubkey matches that of the CSR, and that it's signed by the intended CA
-    if [ ! -s "$x509" ] ||
-         ! diff <(openssl req  -in "$CSR"  -pubkey -noout) \
-                <(openssl x509 -in "$x509" -pubkey -noout) >/dev/null ||
-         ! openssl verify -CAfile "$CAfile" -purpose sslserver -x509_strict <"$x509" >/dev/null; then
-        echo "Error: Got an invalid X.509 certificate from the ACME server!" >&2
-        exit 1
-    fi
-
-    # if it doesn't exist, create the file with mode 0644 minus the process's umask(2)
-    [ -e "$SRVCRT" ] || touch "$SRVCRT"
-    cat "$x509" >"$SRVCRT"
-    [ ! "$DEBUG" ] || openssl x509 -noout -text <"$SRVCRT"
-
-    # add the CA chain
-    if [ ${CHAIN+x} ]; then
-        if [ "${CHAIN:-$SRVCRT}" = "$SRVCRT" ]; then
-            cat "$CAfile" >>"$SRVCRT"
-        else
-            [ -e "$CHAIN" ] || touch "$CHAIN"
-            cat "$SRVCRT" "$CAfile" >"$CHAIN"
-        fi
-    fi
-
-    if [ ! "$QUIET" ]; then
-        echo "X.509 certificate $SRVCRT has been updated or renewed"
-        echo
-        openssl x509 -noout \
-            -text -certopt no_header,no_version,no_pubkey,no_sigdump \
-            -fingerprint -sha256 <"$SRVCRT"
-    fi
-
-    for (( i=0; i<${#NOTIFY[@]}; i++ )); do
-        ${NOTIFY[$i]}
-    done
-fi
+
+END {
+    local $?;
+    $_->() foreach reverse @CLEANUP;
+}