Refactoring to use the account key manager.

1 files changed, 254 insertions, 179 deletions

diff --git a/client b/client
index 5cf0139..70150ca 100755
--- a/client
+++ b/client
@@ -2,7 +2,7 @@
 
 #----------------------------------------------------------------------
 # Let's Encrypt ACME client
-# Copyright © 2015 Guilhem Moulin <guilhem@fripost.org>
+# Copyright © 2015,2016 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
@@ -21,98 +21,170 @@
 use strict;
 use warnings;
 
+# Usage: client COMMAND CONFIG_FD SOCKET_FD [ARGUMENTS]
+#
+# fdopen(3) the file descriptor SOCKET_FD (corresponding to the
+# listening letsencrypt-accountd socket), connect(2) to it to retrieve
+# the account key's public parameters and later send data to be signed
+# by the master component (using the account key).
+#
+# CONFIG_FD is a read-only file descriptor associated with the
+# configuration file at pos 0.  (This is needed since this process
+# doesn't know its name and might not have read access to it.)
+#
+# NOTE: one needs to chdir(2) to an appropriate ACME challenge directory
+# before running this program, since challenge tokens are (on purpose)
+# only written to the current directory.  If COMMAND is challenge-less,
+# one should chdir(2) to the root directory "/" instead.
+#
+# NOTE: one should run this program as an unprivileged user:group such
+# as "nobody:nogroup"; bind(2)'ing to a restricted UNIX socket (for
+# instance own by another user and created with umask 0177) is not a
+# problem since SOCKET_FD can be bound as root prior to the execve(2).
+
+my $PROTOCOL_VERSION = 1;
+
 use LWP::UserAgent ();
-use Crypt::OpenSSL::RSA ();
-use Crypt::OpenSSL::Bignum ();
 use MIME::Base64 qw/encode_base64 encode_base64url/;
 use JSON ();
 use Digest::SHA qw/sha256 sha256_hex/;
 
+use Config::Tiny ();
+
 # Clean up PATH
 $ENV{PATH} = join ':', qw{/usr/bin /bin};
 delete @ENV{qw/IFS CDPATH ENV BASH_ENV/};
 
 my $COMMAND = shift @ARGV // die;
-my $PUBKEY = shift @ARGV // die;
-die unless grep {$COMMAND eq $_} qw/new-reg new-cert revoke-cert/;
-my $TIMEOUT = 10;
 
+# Untaint and fdopen(3) the configuration file and listening socket
+(shift @ARGV // die) =~ /\A(\d+)\z/ or die;
+open my $CONFFILE, '<&=', $1 or die "fdopen $1: $!";
+(shift @ARGV // die) =~ /\A(\d+)\z/ or die;
+open my $S, '+<&=', $1 or die "fdopen $1: $!";
 
-# Read the public key and build the JSON Web Key (RFC 7517)
-my $JWK = do {
-    open my $fh, '<', $PUBKEY or die "Can't open $PUBKEY: $!";
-    my $str = do { local $/ = undef; <$fh> };
-    my $pubkey = Crypt::OpenSSL::RSA->new_public_key($str) or die;
-    close $fh;
 
-    my ($n, $e) = $pubkey->get_key_parameters();
-    $_ = encode_base64url($_->to_bin()) foreach ($n, $e);
+#############################################################################
+# Read the protocol version and JSON Web Key (RFC 7517) from the
+# letsencrypt-accountd socket
+#
+die "Error: Invalid client version\n" unless
+    $S->getline() =~ /\A(\d+) OK(?:.*)\r\n\z/ and $1 == $PROTOCOL_VERSION;
+my $JWK = JSON::->new->decode($S->getline());
 
-    { kty => 'RSA', n => $n, e => $e }
-};
-my $JSON = JSON::->new->utf8->canonical(); # breaks hashes otherwise
-my $JWK_dgst64 = encode_base64url(sha256($JSON->encode($JWK)));
+# JSON keys need to be sorted lexicographically (for instance in the thumbprint)
+sub json() { JSON::->new->utf8->canonical(); }
+
+my $JWK_thumbprint = encode_base64url(sha256(json()->encode($JWK)));
 my $NONCE;
 
 
-# Send an HTTP request to the ACME server
-my $UA = LWP::UserAgent::->new( ssl_opts => {
-    verify_hostname => 1,
-    SSL_version => 'SSLv23:!TLSv1_1:!TLSv1:!SSLv3:!SSLv2',
-    SSL_cipher_list => 'EECDH+AESGCM:!MEDIUM:!LOW:!EXP:!aNULL:!eNULL'
-});
+#############################################################################
+# Parse configuration (already validated by the master) and create the
+# LWP::UserAgent object
+#
+
+my $CONFIG = do {
+    my $conf = do { local $/ = undef, <$CONFFILE> };
+    close $CONFFILE or die "Can't close: $!";
+    my $h = Config::Tiny::->read_string($conf) or die Config::Tiny::->errstr()."\n";
+    $h->{_} //= {};
+    $h->{client}->{$_} //= $h->{_}->{$_} foreach keys %{$h->{_}}; # add defaults
+    $h->{client};
+};
+my $UA = do {
+    my %args = %$CONFIG;
+    my $verify = lc (delete $args{SSL_verify} // 'Yes') eq 'no' ? 0 : 1;
+    my %ssl_opts = ( verify_hostname => $verify );
+    $ssl_opts{$_} = $args{$_} foreach grep /^SSL_/, keys %args;
+    LWP::UserAgent::->new( ssl_opts => \%ssl_opts );
+} // die "Can't create LWP::UserAgent object";
+
+
+#############################################################################
+# Send an HTTP request to the ACME server.  If $json is defined, send
+# its encoding as the request content, with "application/json" as
+# Content-Type.
+#
 sub request($$;$) {
     my ($method, $uri, $json) = @_;
-    print STDERR ">>> $method $uri <<<\n" if $ENV{DEBUG};
+    print STDERR "[$$] >>> $method $uri <<<\n" if $ENV{DEBUG};
 
     my $req = HTTP::Request::->new($method => $uri) or die "Can't $method $uri";
     if (defined $json) {
-        $req->header('Content-Type' => 'application/json');
-        $req->content($JSON->encode($json));
+        $req->content_type('application/json');
+        $req->content(json()->encode($json));
     }
     my $r = $UA->request($req) or die "Can't $method $uri";
-    print STDERR ">>> ", $r->status_line, "\n", $r->headers->as_string, "\n" if $ENV{DEBUG};
-    $NONCE = $r->header('Replay-Nonce') // die;
-    my $t = $r->header('Content-Type');
+    $NONCE = $r->header('Replay-Nonce'); # undef $NONCE if the header is missing
+    print STDERR "[$$] >>> ", $r->status_line, "\n", $r->headers->as_string, "\n" if $ENV{DEBUG};
+    return $r;
+}
 
-    my $content = $r->decoded_content();
-    if (defined $t and $t =~ /\Aapplication\/(?:[a-z]+\+)?json\z/) {
-        $content = $JSON->decode($content);
-        print STDERR $JSON->pretty->encode($content), "\n" if $ENV{DEBUG};
-    }
-    elsif (defined $t and $t eq 'application/pkix-cert') {
-        print STDERR encode_base64($content), "\n" if $ENV{DEBUG};
-    }
-    else {
-        print STDERR $content, "\n" if $ENV{DEBUG};
-    }
-    unless ($r->is_success) {
-        my $msg = $r->status_line;
-        $msg .= " (".$content->{detail}.")" if ref $content and defined $content->{detail};
-        die $msg, "\n";
+# List all 'Links' headers with the relationship $rel (RFC 5988)
+sub request_link_rel($$) {
+    my ($r, $rel) = @_;
+    grep defined, map
+        { /\A<([^>]+)>.*;\s*rel=([^;]+)/
+        ; my ($link, $rels) = ($1, $2 // '')
+        ; (grep { $rel eq $_ } map { /^"(.*)"/ ? $1 : $_ } split(/\s+/, $rels)) ? $link : undef
+        }
+        $r->header('Link');
+}
+
+# The request's Status Line; if the Content-Type is
+# application/problem+json, parse the decoded content as JSON and add
+# the value of the 'detail' field to the Status Line.
+# https://tools.ietf.org/html/draft-ietf-appsawg-http-problem
+sub request_status_line($) {
+    my $r = shift;
+    my $msg = $r->status_line;
+    if ($r->content_type() eq 'application/problem+json') {
+        my $content = json()->decode($r->decoded_content());
+        print STDERR json()->pretty->encode($content), "\n" if $ENV{DEBUG};
+        $msg .= " (".$content->{detail}.")" if defined $content->{detail};
     }
+    return $msg;
+}
 
+# Parse and return the request's decoded content as JSON; or print the
+# Status Line and fail if the request failed.
+# If $dump is set, also pretty-print the decoded content.
+sub request_json_decode($;$) {
+    my $r = shift;
+    my $dump = shift || $ENV{DEBUG};
+    die request_status_line($r), "\n" unless $r->is_success();
+    my $content = $r->decoded_content();
+
+    die "Content-Type: ".$r->content_type()." is not application/json\n"
+        unless $r->content_type() eq 'application/json';
+    $content = json()->decode($content);
+
+    print STDERR json()->pretty->encode($content), "\n" if $dump;
     return $content;
 }
 
 
-# ACME client
-# https://tools.ietf.org/html/draft-ietf-acme-acme-01
+#############################################################################
+# JSON-encode the hash reference $h and send it to the ACME server $uri
+# encapsulated it in a JSON Web Signature (JWS).
+# https://tools.ietf.org/html/draft-ietf-acme-acme
+#
 sub acme($$) {
     my ($uri, $h) = @_;
 
+    # the ACME server MUST provide a Replay-Nonce header field in
+    # response to a HEAD request for any valid resource
+    request(HEAD => $uri) unless defined $NONCE;
+
     # Produce the JSON Web Signature: RFC 7515 section 5
-    my $payload = encode_base64url($JSON->encode($h));
+    my $payload = encode_base64url(json()->encode($h));
     my %header = ( alg => 'RS256', jwk => $JWK );
-    my $protected = encode_base64url($JSON->encode({ %header, nonce => $NONCE }));
+    my $protected = encode_base64url(json()->encode({ %header, nonce => $NONCE }));
     my $data = $protected .'.'. $payload;
-    print STDERR "Requesting a SHA-256 signature for ", $data, "\n" if $ENV{DEBUG};
-    STDOUT->printflush($data, "\n");
-
-    # Ask for an (hex) sig
-    my $sig = do { local $_ = <STDIN>; chomp; $_ };
-    $sig = encode_base64url(pack('H*', $sig));
-    print STDERR "Got SHA-256 signature ", $sig, "\n" if $ENV{DEBUG};
+    $S->printflush($data, "\r\n");
+    my $sig = $S->getline();
+    $sig =~ s/\r\n\z// or die;
 
     # Flattened JSON Serialization, RFC 7515 section 7.2.2
     request(POST => $uri, {
@@ -123,147 +195,150 @@ sub acme($$) {
     });
 }
 
-
-# Query the root ACME directory to initialize the nonce and get the resources URIs
-my %RES = %{ request(GET => "https://acme-v01.api.letsencrypt.org/directory") };
+my $SERVER_URI = $CONFIG->{server} // 'https://acme-v01.api.letsencrypt.org/';
+$SERVER_URI .= '/' unless substr($SERVER_URI, -1, 1) eq '/';
+
+my %RES;
+# Get the resource URI from the directory
+sub acme_resource($%) {
+    my $r = shift;
+    # Query the root ACME directory to initialize the nonce and get the resources URIs
+    %RES = %{ request_json_decode(request(GET => $SERVER_URI.'directory')) } unless %RES;
+    my $uri = $RES{$r} // die "Missing ressource for \"$r\"\n";
+    acme($uri, {resource => $r, @_});
+}
 
 
+#############################################################################
+# new-reg AGREEMENT_URI [CONTACT ..]
+#
 if ($COMMAND eq 'new-reg') {
+    my $agreement = shift @ARGV;
     print STDERR "Requesting new registration ".(@ARGV ? ("for ".join(', ', @ARGV)) : "")."\n";
-    my $uri = "https://letsencrypt.org/documents/LE-SA-v1.0.1-July-27-2015.pdf";
-    my $dgst = sha256_hex($UA->get($uri)->decoded_content());
-    die "Error: The CA's subscriber agreement (URL $uri) has changed!\n" if
-        $dgst ne '33d233c8ab558ba6c8ebc370a509acdded8b80e5d587aa5d192193f35226540f';
-
-    acme($RES{'new-reg'}, {
-        resource => 'new-reg',
-        contact => [ map {"mailto:$_"} @ARGV ],
-        agreement => $uri,
-    });
-    exit;
-}
 
+    my %h = (contact => \@ARGV);
+    $h{agreement} = $agreement if $agreement ne '';
+    my $r = acme_resource('new-reg', %h);
 
-if ($COMMAND eq 'revoke-cert') {
-    print STDERR "Requesting revocation for\n";
-    for my $cert (@ARGV) {
-        open my $fh1, '-|', qw/openssl x509 -noout -subject -serial -fingerprint -sha256/, '-in', $cert
-            or die "Can't run x509(1ssl): $!";
-        my ($subject, $serial, $fingerprint) = map { s/[^=]+=\s*//; chomp; $_ } <$fh1>;
-        close $fh1;
-
-        print STDERR "\n\tSubject:             $subject\n",
-                       "\tSerial:              $serial\n",
-                       "\tSHA-256 fingerprint: $fingerprint\n";
+    my ($terms) = request_link_rel($r, 'terms-of-service');
+    request_json_decode($r,1) if $r->is_success() and $ENV{DEBUG}; # pretty-print the JSON
+    print STDERR request_status_line($r), "\n";
+    print STDERR "Subscriber Agreement URI: $terms\n" if defined $terms;
+    print STDERR "Registration URI: ", $r->header('Location'), "\n";
+    exit ($r->is_success() ? 0 : 1);
+}
 
-        open my $fh2, '-|', qw/openssl x509 -outform DER/, '-in', $cert or die "Can't run x509(1ssl): $!";
-        my $der = do { local $/ = undef; <$fh2> };
-        close $fh2;
 
-        acme($RES{'revoke-cert'}, {
-            resource => 'revoke-cert',
-            certificate => encode_base64url($der)
-        });
-    }
-    exit;
+#############################################################################
+# reg=URI AGREEMENT_URI [CONTACT ..]
+#
+elsif ($COMMAND =~ /\Areg=(\p{Print}+)\Z/) {
+    die "Empty registration URI (use the 'new-reg' command to determine the URI)\n" if $1 eq '';
+    my $uri = $SERVER_URI.$1;
+    my $agreement = shift @ARGV;
+
+    my %h = (resource => 'reg');
+    $h{agreement} = $agreement if $agreement ne '';
+    $h{contact} = \@ARGV if @ARGV; # don't empty the contact list
+    my $r = acme($uri, \%h);
+
+    my ($terms) = request_link_rel($r, 'terms-of-service');
+    $r->is_success() ? request_json_decode($r,1)  # pretty-print the JSON
+                     : print STDERR request_status_line($r), "\n";
+    print STDERR "Subscriber Agreement URI: $terms\n" if defined $terms;
+    exit ($r->is_success() ? 0 : 1);
 }
 
 
-# $COMMAND eq 'new-cert'
-my ($CSR, $CHALLENGE_DIR, $X509) = @ARGV;
-$CHALLENGE_DIR = $CHALLENGE_DIR =~ /\A(\/\p{Print}+)\z/ ? $1 :
-    die "Error: Challenge directory is not absolute: $CHALLENGE_DIR";
-
-# Parse the Certificate Signing Request
-# XXX use a library instead, perhaps Crypt::OpenSSL::PKCS10
-my @domains = do {
-    my @req = (qw/openssl req -noout/, '-in', $CSR);
-
-    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)+/;
-    my %domains;
-
-    open my $fh1, '-|', @req, '-subject' or die "Can't run req(1ssl): $!";
-    my $subject = <$fh1>;
-    close $fh1;
-    $domains{$1} = 1 if $subject =~ /\Asubject=.*\/CN=($RE_domain)\n\z/o;
-
-    open my $fh2, '-|', @req, '-text', '-reqopt', 'no_header,no_version,no_subject,no_pubkey,no_sigdump'
-        or die "Can't run req(1ssl): $!";
-    while (<$fh2>) {
-        /\A\s+X509v3 Subject Alternative Name:/ or next;
-        my $san = <$fh2>;
-        foreach (split /,/, $san) {
-            chomp;
-            s/\A\s*//;
-            next unless s/\ADNS://;
-            if (/\A$RE_domain\z/o) {
-                $domains{$_} = 1;
-            }
-            else {
-                warn "WARNING: Ignoring invalid domain $_\n";
-            }
+#############################################################################
+# new-cert AUTHZ [AUTHZ ..]
+#   Read the CSR (in DER format) from STDIN, print the cert (in PEM format
+#   to STDOUT)
+#
+elsif ($COMMAND eq 'new-cert') {
+    die unless @ARGV;
+    foreach my $domain (@ARGV) {
+        print STDERR "Processing new DNS authz for $domain\n" if $ENV{DEBUG};
+        my $r = acme_resource('new-authz', identifier => {type => 'dns', value => $domain});
+
+        my ($challenge) = grep {$_->{type} eq 'http-01'}
+                               @{request_json_decode($r)->{challenges} // []};
+        die "Missing 'http-01' challenge in server response" unless defined $challenge;
+        die "Invalid challenge token ".($challenge->{token} // '')."\n"
+            unless ($challenge->{token} // '') =~ /\A[A-Za-z0-9_\-]+\z/;
+
+        my $keyAuthorization = $challenge->{token}.'.'.$JWK_thumbprint;
+
+        # serve $keyAuthorization at http://$domain/.well-known/acme-challenge/$challenge->{token}
+        if (-e $challenge->{token}) {
+            print STDERR "WARNING: File exists: $challenge->{token}\n";
+        }
+        else {
+            open my $fh, '>', $challenge->{token} or die "Can't open $challenge->{token}: $!";
+            $fh->print($keyAuthorization);
+            $fh->close() or die "Can't close: $!";
         }
-        last;
-    }
-    close $fh2;
-
-    keys %domains;
-};
-print STDERR "Found domain(s): ".join(", ", @domains), "\n" if $ENV{DEBUG};
-
 
-# Process DNS Authorizations
-foreach my $domain (@domains) {
-    print STDERR "Processing new DNS authz for $domain\n" if $ENV{DEBUG};
-    my $challenges = acme($RES{'new-authz'}, {
-        resource => 'new-authz',
-        identifier => { type => 'dns', value => $domain }
-    });
-    die "No challenge in server response" unless defined $challenges->{challenges};
-    my ($challenge) = grep {$_->{type} eq 'http-01'} @{$challenges->{challenges}};
-    my $keyAuthorization = $challenge->{token}.'.'.$JWK_dgst64;
-
-    # serve $keyAuthorization at http://$domain/.well-known/acme-challenge/$challenge->{token}
-    my $filename = $CHALLENGE_DIR.'/'.$challenge->{token};
-    if (-e $filename) {
-        warn "WARNING: File exists: $filename\n";
-    }
-    else {
-        open my $fh, '>', $filename or die "Can't open $filename: $!";
-        print $fh $keyAuthorization;
-        close $fh;
+        $r = acme($challenge->{uri}, {
+            resource => 'challenge',
+            keyAuthorization => $keyAuthorization
+        });
+        # wait until the status become 'valid'
+        for ( my $i = 0, my $status;
+              $status = request_json_decode($r)->{status} // 'pending',
+              $status ne 'valid';
+              $r = request('GET' => $challenge->{uri}), $i++ ) {
+            die "Error: Invalid challenge for $domain (status: ".$status.")\n" if $status ne 'pending';
+            die "Timeout exceeded while waiting for challenge to pass ($domain)\n"
+                if $i >= ($CONFIG->{timeout} // 10);
+            sleep 1;
+        }
     }
 
-    acme($challenge->{uri}, {
-        resource => 'challenge',
-        keyAuthorization => $keyAuthorization
-    });
+    my $csr = do { local $/ = undef; <STDIN> };
+    my $r = acme_resource('new-cert', csr => encode_base64url($csr));
+    die request_status_line($r), "\n" unless $r->is_success();
+    my $uri = $r->header('Location');
+    # https://acme-v01.api.letsencrypt.org/acme/cert/$serial
+    print STDERR "Certificate URI: $uri\n";
 
-    for (my $i=0;; $i++) {
-        my $status = request('GET' => $challenge->{uri})->{status} // 'pending';
-        die "Error: Invalid challenge for $domain\n" if $status eq 'invalid';
-        last if $status eq 'valid';
-        die "Timeout exceeded while waiting for challenge to pass ($domain)\n" if $i >= $TIMEOUT;
+    # wait for the cert
+    for (my $i = 0; $r->decoded_content() eq ''; $r = request('GET' => $uri), $i++) {
+        die request_status_line($r), "\n" unless $r->is_success();
+        die "Timeout exceeded while waiting for certificate\n"
+            if $i >= ($CONFIG->{timeout} // 10);
         sleep 1;
     }
-}
-
+    my $der = $r->decoded_content();
+
+    # conversion DER -> PEM
+    pipe my $rd, my $wd or die "Can't pipe: $!";
+    my $pid = fork // die "Can't fork: $!";
+    unless ($pid) {
+        open STDIN, '<&', $rd or die "Can't dup: $!";
+        exec qw/openssl x509 -inform DER -outform PEM/ or die;
+    }
+    $rd->close() or die "Can't close: $!";
+    $wd->print($der);
+    $wd->close() or die "Can't close: $!";
 
-do {
-    print STDERR "Processing new CSR\n" if $ENV{DEBUG};
-    open my $fh1, '-|', qw/openssl req -outform DER/, '-in', $CSR or die "Can't run req(1ssl): $!";
-    my $req = do { local $/ = undef; <$fh1> };
-    close $fh1;
+    waitpid $pid => 0;
+    die $? if $? > 0;
+}
 
-    # The server also gives the cert URI in its 'Location' header in
-    # https://acme-v01.api.letsencrypt.org/acme/cert/$serial
-    my $x509 = acme($RES{'new-cert'}, {
-        resource => 'new-cert',
-        csr => encode_base64url($req)
-    });
 
-    open my $fh2, '|-', qw/openssl x509 -inform DER/, '-out', $X509 or die "Can't run x509(1ssl): $!";
-    print $fh2 $x509;
-    close $fh2;
-};
+#############################################################################
+# revoke-cert
+#   The certificate to revoke is passed (in DER format) to STDIN; this
+#   is required since the ACME client might not have read access to the
+#   X.509 file
+#
+elsif ($COMMAND eq 'revoke-cert') {
+    die if @ARGV;
+    my $der = do { local $/ = undef; <STDIN> };
+    close STDIN or die "Can't close: $!";
+
+    my $r = acme_resource('revoke-cert', certificate => encode_base64url($der));
+    exit 0 if $r->is_success();
+    die request_status_line($r), "\n";
+}