AnyEvent/MCP/Config.pm

=head1 NAME

AnyEvent::MCP::Config - named servers and derived MCP credentials

=head1 SYNOPSIS

   my $config = AnyEvent::MCP::Config->global;
   my $password = $config->credential ("basic", "agni", "alice");
   my $url = $config->url ("agni");

=head1 DESCRIPTION

An MCP server and its clients often need matching credentials. Rather than
maintaining a separate password for each server and user, this module can
derive them from one private master secret. A server name, optional username
and credential purpose each contribute to the result. A password derived for
one server is therefore not the password for another.

The shared file format is described in L<AnyEvent::MCP/GLOBAL CONFIGURATION>.
Loading this module does not read any files. The first call to C<global>
reads the configuration, ensures a master secret exists and caches the object
for the process.

A missing secret is generated using C<AnyEvent::MCP::random_bytes> and saved
when possible. Saving failure produces a warning; the generated secret remains
usable in this process, but another process might derive different credentials.
A supplied invalid secret is an error. Changing or losing the master secret
invalidates all credentials derived from it.

Derivation uses HKDF-SHA512 expansion with the random master key as its PRK.
Server name, username and credential purpose are separately length-prefixed,
so credentials for different servers, users or authentication methods differ.
Deriving a password does not create an account or configure the server to
accept it: authentication still belongs to the server.

=head1 METHODS

=head2 $config = AnyEvent::MCP::Config->global (file => $file)

Returns the cached global configuration. The first call accepts the same
arguments as C<new>; later calls return the same object without rereading
the file. Call this explicitly during program startup.

=head2 $config = AnyEvent::MCP::Config->new (file => $file)

Reads C<$file>, or the default file when omitted, and ensures a master
secret exists. Unlike C<global>, each call creates an independent object.
A missing file is allowed; other read errors are fatal. Sections are available
as C<< $config->{section}{$section} >>, each a hash reference of string
values. Named servers use C<[server NAME]>.

=head2 $config = AnyEvent::MCP::Config->init (file => $file)

Explicitly creates the configuration file with a random secret, mode 0600.
Creates missing parent directories with mode 0700. Fails if the file already
exists, so it cannot accidentally replace an existing secret.

=head2 $credential = $config->credential ($purpose, $name, $username)

Derives a 32-byte credential, returned as unpadded URL-safe Base64.
C<$purpose> is C<basic>, C<bearer> or C<cookie>. C<$name> is the server
name. C<$username> can be omitted for a server-wide credential.

This method does not require a corresponding server section.

=head2 $url = $config->url ($name, $username)

Returns the configured C<url> for C<$name>, replacing C<{cookie}> with the
derived cookie credential. C<$username> can be omitted.

The template supplies scheme, host, port, path and cookie placement explicitly.
This method neither contacts a server nor infers an ephemeral listening port.
The HTTP server does not consume this configuration automatically.

=head2 $name = AnyEvent::MCP::Config::server_name ($name)

Validate a service-instance name, or use the program basename if undefined.
Names consist of an ASCII letter or underscore followed by letters, digits,
underscores or hyphens.

=head2 @options = AnyEvent::MCP::Config::http_getopt (\$name, \$bind, \$print_url)

Return standard C<Getopt::Long> options referring to the caller's scalars.

=head2 $port = $config->server_port ($name)

Derive a stable default port in 16384..32767 from the master secret and
service-instance name. Collisions produce ordinary listener bind errors.

=head2 %settings = $config->http_settings ($name, $bind)

Resolve HTTP settings from C<[server NAME]> and an optional command-line
C<bind> override. The default is IPv4 loopback and the name-derived port.
The bind setting accepts C<ADDRESS:PORT>, C<[IPv6]:PORT>, C<ADDRESS>,
and C<:PORT> (which keeps the default loopback address).
Hostnames are resolved once to a numeric address at startup; their original
spelling is advertised unless C<url_host> overrides it.

=head2 $url = $config->http_url ($name, $bind, %options)

Format the cookie URL without opening a listener. Port zero cannot be used
because the kernel has not yet selected a port.

=cut

package AnyEvent::MCP::Config;

use common::sense;
use AnyEvent::MCP ();
use MIME::Base64 ();
use File::Basename ();
use File::Path ();
use Fcntl qw(O_WRONLY O_RDWR O_CREAT O_EXCL LOCK_EX);
use Errno qw(ENOENT);
use AnyEvent::Socket ();
use Socket ();

our @ISA = qw(AnyEvent::MCP::Base);

sub _file {
   my $dir = $ENV{XDG_CONFIG_HOME}
      || ($ENV{HOME} || die "HOME is not set\n") . "/.config";

   "$dir/anyevent-mcp/global.ini"
}

my $global;

sub global {
   my $class = shift;

   $global ||= $class->new (@_)
}

sub new {
   my ($class, %kv) = @_;
   my $self = $class->SUPER::new (section => {}, %kv);
   $self->{file} = _file unless exists $self->{file};

   if (open my $fh, "<:encoding(UTF-8)", $self->{file}) {
      $self->_read ($fh);
      close $fh or die "$self->{file}: $!\n";
   } else {
      die "$self->{file}: $!\n" unless $! == ENOENT;
   }

   $self->_ensure_secret;

   die "$self->{file}: invalid secret; supply 128 hexadecimal digits\n"
      unless $self->{section}{global}{secret} =~ /\A[0-9a-fA-F]{128}\z/;

   $self
}

sub _read {
   my ($self, $fh) = @_;

   my @stat = stat $fh;
   die "$self->{file}: configuration must be private and owned by this user\n"
      if $stat[4] != $< || $stat[2] & 077;

   my $section = $self->{section}{global} ||= {};

   while (<$fh>) {
      next if /\A\s*(?:[#;]|\z)/;

      if (/\A\s*\[([^\]\r\n]+)\]\s*\z/) {
         $section = $self->{section}{$1} ||= {};
      } elsif (/\A\s*([^=\s]+)\s*=\s*(.*?)\s*\z/) {
         $section->{$1} = $2;
      } else {
         die "$self->{file}:$.: invalid configuration line\n";
      }
   }

}

sub _ensure_secret {
   my ($self) = @_;

   return if exists $self->{section}{global}{secret};

   my $secret = eval { unpack "H*", AnyEvent::MCP::random_bytes 64 };
   die "$@Supply a securely generated 128-digit hexadecimal secret in $self->{file}\n"
      if $@;

   eval {
      File::Path::mkpath (File::Basename::dirname ($self->{file}), 0, 0700);
      sysopen my $fh, $self->{file}, O_RDWR | O_CREAT, 0600
         or die "$self->{file}: $!\n";
      flock $fh, LOCK_EX or die "$self->{file}: $!\n";
      binmode $fh, ":encoding(UTF-8)";

      my $disk = bless { file => $self->{file}, section => {} }, ref $self;
      $disk->_read ($fh);

      unless (exists $disk->{section}{global}{secret}) {
         seek $fh, 0, 2 or die "$self->{file}: $!\n";
         print {$fh} "\n[global]\nsecret = $secret\n"
            or die "$self->{file}: $!\n";
         $disk->{section}{global}{secret} = $secret;
      }

      close $fh or die "$self->{file}: $!\n";
      $self->{section} = $disk->{section};
      1
   } or warn "Cannot save MCP master secret; credentials may only be stable for this process: $@";

   $self->{section}{global}{secret} = $secret
      unless exists $self->{section}{global}{secret};
}

sub init {
   my ($class, %kv) = @_;
   my $file = exists $kv{file} ? $kv{file} : _file;

   my $secret = AnyEvent::MCP::random_bytes 64;

   File::Path::mkpath (File::Basename::dirname ($file), 0, 0700);

   sysopen my $fh, $file, O_WRONLY | O_CREAT | O_EXCL, 0600
      or die "$file: $!\n";

   print {$fh} "[global]\nsecret = ", unpack ("H*", $secret), "\n"
      or die "$file: $!\n";
   close $fh or die "$file: $!\n";

   $class->new (file => $file)
}

sub credential {
   my ($self, $purpose, $name, $username) = @_;

   $username = "" unless defined $username;

   die "Unknown credential purpose '$purpose'\n"
      unless $purpose =~ /\A(?:basic|bearer|cookie)\z/;

   my $secret = $self->{section}{global}{secret};
   die "$self->{file}: missing or invalid secret\n"
      unless $secret =~ /\A[0-9a-fA-F]{128}\z/;

   my $info = pack "N/a*N/a*N/a*N/a*",
      "AnyEvent::MCP credential v1", $purpose,
      AnyEvent::MCP::utf8enc ($name), AnyEvent::MCP::utf8enc ($username);

   my $credential = MIME::Base64::encode_base64 (
      AnyEvent::MCP::hkdf_sha512_expand (pack ("H*", $secret), $info, 32), ""
   );
   $credential =~ y!+/=!-_!d;

   $credential
}

sub server_name {
   my ($name) = @_;

   unless (defined $name) {
      require File::Basename;
      $name = File::Basename::basename ($0);
      $name =~ s/\.(?:pl|perl)\z//;
      $name = "perl" if $name eq "-e";
   }

   $name =~ /\A[A-Za-z_][A-Za-z0-9_-]*\z/
      or die "Invalid MCP server name '$name'\n";

   $name
}

sub http_getopt {
   my ($name, $bind, $print_url) = @_;

   "name=s" => $name, "bind=s" => $bind, "print-url" => $print_url
}

sub server_port {
   my ($self, $name) = @_;

   $name = server_name $name;

   my $info = pack "N/a*N/a*", "AnyEvent::MCP port v1", $name;
   16384 + ((unpack "n", AnyEvent::MCP::hkdf_sha512_expand (
      pack ("H*", $self->{section}{global}{secret}), $info, 2
   )) & 16383)
}

sub http_settings {
   my ($self, $name, $bind) = @_;

   $name = server_name $name;
   my $settings = $self->{section}{"server $name"} || {};
   my $port = $self->server_port ($name);
   my $configured = $settings->{bind} // "127.0.0.1:$port";
   $configured = "127.0.0.1$configured" if $configured =~ /\A:[0-9]+\z/;
   my ($configured_host, $configured_port) = AnyEvent::Socket::parse_hostport $configured, $port;
   defined $configured_host && defined $configured_port
      && $configured_port =~ /\A[0-9]+\z/ && $configured_port <= 65535
      or die "Invalid MCP bind address '$configured'\n";

   $bind = $configured unless defined $bind;
   $bind = "127.0.0.1$bind" if $bind =~ /\A:[0-9]+\z/;

   my ($host, $service) = AnyEvent::Socket::parse_hostport $bind, $configured_port;
   defined $host && defined $service && $service =~ /\A[0-9]+\z/ && $service <= 65535
      or die "Invalid MCP bind address '$bind'\n";

   my %kv = (
      (map { exists $settings->{$_} ? ($_ => $settings->{$_}) : () }
         qw(path url_host url_scheme cookie bearer users)),
      name => $name,
      host => $host,
      port => $service,
   );

   unless (AnyEvent::Socket::parse_address $host) {
      my ($error, @addresses) = Socket::getaddrinfo ($host, undef, { socktype => Socket::SOCK_STREAM () });
      !$error && @addresses
         or die "Cannot resolve MCP bind host '$host': $error\n";

      my ($error2, $address) = Socket::getnameinfo ($addresses[0]{addr}, Socket::NI_NUMERICHOST ());
      !$error2 && length $address
         or die "Cannot format MCP bind host '$host': $error2\n";

      $kv{url_host} //= $host;
      $kv{host} = $address;
   }

   unless (grep exists $kv{$_}, qw(cookie bearer users)) {
      my $token = $self->credential ("cookie", $name);
      @kv{qw(cookie bearer)} = ($token, $token);
   }

   %kv
}

sub http_url {
   my ($self, $name, $bind, %options) = @_;

   # A printed URL needs a credential that survives the next process.
   my $stored = ref ($self)->new (file => $self->{file});
   $stored->{section}{global}{secret} eq $self->{section}{global}{secret}
      or die "MCP master secret is not persistently stored in $self->{file}\n";

   require AnyEvent::MCP::Server::HTTP;
   my $server = AnyEvent::MCP::Server::HTTP->new ($self->http_settings ($name, $bind), %options);
   $server->url
}

sub url {
   my ($self, $name, $username) = @_;

   my $url = $self->{section}{"server $name"}{url}
      or die "No URL configured for server '$name'\n";

   $url =~ s/\{cookie\}/$self->credential ("cookie", $name, $username)/ge;

   $url
}

1
Revision:	1.4
Committed:	Sat Oct 10 10:48:51 2026 UTC (2 weeks, 6 days ago) by root
Branch:	MAIN
Changes since 1.3:	+126 -0 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			AnyEvent::MCP::Config - named servers and derived MCP credentials
4
5			=head1 SYNOPSIS
6
7			my $config = AnyEvent::MCP::Config->global;
8			my $password = $config->credential ("basic", "agni", "alice");
9			my $url = $config->url ("agni");
10
11			=head1 DESCRIPTION
12
13	root	1.3	An MCP server and its clients often need matching credentials. Rather than
14			maintaining a separate password for each server and user, this module can
15			derive them from one private master secret. A server name, optional username
16			and credential purpose each contribute to the result. A password derived for
17			one server is therefore not the password for another.
18
19			The shared file format is described in L<AnyEvent::MCP/GLOBAL CONFIGURATION>.
20			Loading this module does not read any files. The first call to C<global>
21			reads the configuration, ensures a master secret exists and caches the object
22			for the process.
23	root	1.1
24			A missing secret is generated using C<AnyEvent::MCP::random_bytes> and saved
25			when possible. Saving failure produces a warning; the generated secret remains
26	root	1.3	usable in this process, but another process might derive different credentials.
27			A supplied invalid secret is an error. Changing or losing the master secret
28			invalidates all credentials derived from it.
29	root	1.1
30			Derivation uses HKDF-SHA512 expansion with the random master key as its PRK.
31			Server name, username and credential purpose are separately length-prefixed,
32			so credentials for different servers, users or authentication methods differ.
33	root	1.3	Deriving a password does not create an account or configure the server to
34			accept it: authentication still belongs to the server.
35	root	1.1
36			=head1 METHODS
37
38			=head2 $config = AnyEvent::MCP::Config->global (file => $file)
39
40			Returns the cached global configuration. The first call accepts the same
41			arguments as C<new>; later calls return the same object without rereading
42			the file. Call this explicitly during program startup.
43
44			=head2 $config = AnyEvent::MCP::Config->new (file => $file)
45
46			Reads C<$file>, or the default file when omitted, and ensures a master
47			secret exists. Unlike C<global>, each call creates an independent object.
48			A missing file is allowed; other read errors are fatal. Sections are available
49			as C<< $config->{section}{$section} >>, each a hash reference of string
50			values. Named servers use C<[server NAME]>.
51
52			=head2 $config = AnyEvent::MCP::Config->init (file => $file)
53
54			Explicitly creates the configuration file with a random secret, mode 0600.
55			Creates missing parent directories with mode 0700. Fails if the file already
56			exists, so it cannot accidentally replace an existing secret.
57
58			=head2 $credential = $config->credential ($purpose, $name, $username)
59
60			Derives a 32-byte credential, returned as unpadded URL-safe Base64.
61			C<$purpose> is C<basic>, C<bearer> or C<cookie>. C<$name> is the server
62			name. C<$username> can be omitted for a server-wide credential.
63
64			This method does not require a corresponding server section.
65
66			=head2 $url = $config->url ($name, $username)
67
68			Returns the configured C<url> for C<$name>, replacing C<{cookie}> with the
69			derived cookie credential. C<$username> can be omitted.
70
71			The template supplies scheme, host, port, path and cookie placement explicitly.
72			This method neither contacts a server nor infers an ephemeral listening port.
73			The HTTP server does not consume this configuration automatically.
74
75	root	1.4	=head2 $name = AnyEvent::MCP::Config::server_name ($name)
76
77			Validate a service-instance name, or use the program basename if undefined.
78			Names consist of an ASCII letter or underscore followed by letters, digits,
79			underscores or hyphens.
80
81			=head2 @options = AnyEvent::MCP::Config::http_getopt (\$name, \$bind, \$print_url)
82
83			Return standard C<Getopt::Long> options referring to the caller's scalars.
84
85			=head2 $port = $config->server_port ($name)
86
87			Derive a stable default port in 16384..32767 from the master secret and
88			service-instance name. Collisions produce ordinary listener bind errors.
89
90			=head2 %settings = $config->http_settings ($name, $bind)
91
92			Resolve HTTP settings from C<[server NAME]> and an optional command-line
93			C<bind> override. The default is IPv4 loopback and the name-derived port.
94			The bind setting accepts C<ADDRESS:PORT>, C<[IPv6]:PORT>, C<ADDRESS>,
95			and C<:PORT> (which keeps the default loopback address).
96			Hostnames are resolved once to a numeric address at startup; their original
97			spelling is advertised unless C<url_host> overrides it.
98
99			=head2 $url = $config->http_url ($name, $bind, %options)
100
101			Format the cookie URL without opening a listener. Port zero cannot be used
102			because the kernel has not yet selected a port.
103
104	root	1.1	=cut
105
106			package AnyEvent::MCP::Config;
107
108			use common::sense;
109			use AnyEvent::MCP ();
110			use MIME::Base64 ();
111			use File::Basename ();
112			use File::Path ();
113			use Fcntl qw(O_WRONLY O_RDWR O_CREAT O_EXCL LOCK_EX);
114			use Errno qw(ENOENT);
115	root	1.4	use AnyEvent::Socket ();
116			use Socket ();
117	root	1.1
118			our @ISA = qw(AnyEvent::MCP::Base);
119
120			sub _file {
121			my $dir = $ENV{XDG_CONFIG_HOME}
122			\|\| ($ENV{HOME} \|\| die "HOME is not set\n") . "/.config";
123
124			"$dir/anyevent-mcp/global.ini"
125			}
126
127			my $global;
128
129			sub global {
130			my $class = shift;
131
132			$global \|\|= $class->new (@_)
133			}
134
135			sub new {
136			my ($class, %kv) = @_;
137			my $self = $class->SUPER::new (section => {}, %kv);
138			$self->{file} = _file unless exists $self->{file};
139
140			if (open my $fh, "<:encoding(UTF-8)", $self->{file}) {
141			$self->_read ($fh);
142			close $fh or die "$self->{file}: $!\n";
143			} else {
144			die "$self->{file}: $!\n" unless $! == ENOENT;
145			}
146
147			$self->_ensure_secret;
148
149			die "$self->{file}: invalid secret; supply 128 hexadecimal digits\n"
150			unless $self->{section}{global}{secret} =~ /\A[0-9a-fA-F]{128}\z/;
151
152			$self
153			}
154
155			sub _read {
156			my ($self, $fh) = @_;
157
158			my @stat = stat $fh;
159			die "$self->{file}: configuration must be private and owned by this user\n"
160			if $stat[4] != $< \|\| $stat[2] & 077;
161
162			my $section = $self->{section}{global} \|\|= {};
163
164			while (<$fh>) {
165			next if /\A\s*(?:[#;]\|\z)/;
166
167			if (/\A\s\[([^\]\r\n]+)\]\s\z/) {
168			$section = $self->{section}{$1} \|\|= {};
169			} elsif (/\A\s([^=\s]+)\s=\s(.?)\s*\z/) {
170			$section->{$1} = $2;
171			} else {
172			die "$self->{file}:$.: invalid configuration line\n";
173			}
174			}
175
176			}
177
178			sub _ensure_secret {
179			my ($self) = @_;
180
181			return if exists $self->{section}{global}{secret};
182
183			my $secret = eval { unpack "H*", AnyEvent::MCP::random_bytes 64 };
184			die "$@Supply a securely generated 128-digit hexadecimal secret in $self->{file}\n"
185			if $@;
186
187			eval {
188			File::Path::mkpath (File::Basename::dirname ($self->{file}), 0, 0700);
189			sysopen my $fh, $self->{file}, O_RDWR \| O_CREAT, 0600
190			or die "$self->{file}: $!\n";
191			flock $fh, LOCK_EX or die "$self->{file}: $!\n";
192			binmode $fh, ":encoding(UTF-8)";
193
194			my $disk = bless { file => $self->{file}, section => {} }, ref $self;
195			$disk->_read ($fh);
196
197			unless (exists $disk->{section}{global}{secret}) {
198			seek $fh, 0, 2 or die "$self->{file}: $!\n";
199			print {$fh} "\n[global]\nsecret = $secret\n"
200			or die "$self->{file}: $!\n";
201			$disk->{section}{global}{secret} = $secret;
202			}
203
204			close $fh or die "$self->{file}: $!\n";
205			$self->{section} = $disk->{section};
206			1
207			} or warn "Cannot save MCP master secret; credentials may only be stable for this process: $@";
208
209			$self->{section}{global}{secret} = $secret
210			unless exists $self->{section}{global}{secret};
211			}
212
213			sub init {
214			my ($class, %kv) = @_;
215			my $file = exists $kv{file} ? $kv{file} : _file;
216
217			my $secret = AnyEvent::MCP::random_bytes 64;
218
219			File::Path::mkpath (File::Basename::dirname ($file), 0, 0700);
220
221			sysopen my $fh, $file, O_WRONLY \| O_CREAT \| O_EXCL, 0600
222			or die "$file: $!\n";
223
224			print {$fh} "[global]\nsecret = ", unpack ("H*", $secret), "\n"
225			or die "$file: $!\n";
226			close $fh or die "$file: $!\n";
227
228			$class->new (file => $file)
229			}
230
231			sub credential {
232			my ($self, $purpose, $name, $username) = @_;
233
234			$username = "" unless defined $username;
235
236			die "Unknown credential purpose '$purpose'\n"
237			unless $purpose =~ /\A(?:basic\|bearer\|cookie)\z/;
238
239			my $secret = $self->{section}{global}{secret};
240			die "$self->{file}: missing or invalid secret\n"
241			unless $secret =~ /\A[0-9a-fA-F]{128}\z/;
242
243			my $info = pack "N/aN/aN/aN/a",
244			"AnyEvent::MCP credential v1", $purpose,
245	root	1.2	AnyEvent::MCP::utf8enc ($name), AnyEvent::MCP::utf8enc ($username);
246	root	1.1
247			my $credential = MIME::Base64::encode_base64 (
248			AnyEvent::MCP::hkdf_sha512_expand (pack ("H*", $secret), $info, 32), ""
249			);
250			$credential =~ y!+/=!-_!d;
251
252			$credential
253			}
254
255	root	1.4	sub server_name {
256			my ($name) = @_;
257
258			unless (defined $name) {
259			require File::Basename;
260			$name = File::Basename::basename ($0);
261			$name =~ s/\.(?:pl\|perl)\z//;
262			$name = "perl" if $name eq "-e";
263			}
264
265			$name =~ /\A[A-Za-z_][A-Za-z0-9_-]*\z/
266			or die "Invalid MCP server name '$name'\n";
267
268			$name
269			}
270
271			sub http_getopt {
272			my ($name, $bind, $print_url) = @_;
273
274			"name=s" => $name, "bind=s" => $bind, "print-url" => $print_url
275			}
276
277			sub server_port {
278			my ($self, $name) = @_;
279
280			$name = server_name $name;
281
282			my $info = pack "N/aN/a", "AnyEvent::MCP port v1", $name;
283			16384 + ((unpack "n", AnyEvent::MCP::hkdf_sha512_expand (
284			pack ("H*", $self->{section}{global}{secret}), $info, 2
285			)) & 16383)
286			}
287
288			sub http_settings {
289			my ($self, $name, $bind) = @_;
290
291			$name = server_name $name;
292			my $settings = $self->{section}{"server $name"} \|\| {};
293			my $port = $self->server_port ($name);
294			my $configured = $settings->{bind} // "127.0.0.1:$port";
295			$configured = "127.0.0.1$configured" if $configured =~ /\A:[0-9]+\z/;
296			my ($configured_host, $configured_port) = AnyEvent::Socket::parse_hostport $configured, $port;
297			defined $configured_host && defined $configured_port
298			&& $configured_port =~ /\A[0-9]+\z/ && $configured_port <= 65535
299			or die "Invalid MCP bind address '$configured'\n";
300
301			$bind = $configured unless defined $bind;
302			$bind = "127.0.0.1$bind" if $bind =~ /\A:[0-9]+\z/;
303
304			my ($host, $service) = AnyEvent::Socket::parse_hostport $bind, $configured_port;
305			defined $host && defined $service && $service =~ /\A[0-9]+\z/ && $service <= 65535
306			or die "Invalid MCP bind address '$bind'\n";
307
308			my %kv = (
309			(map { exists $settings->{$_} ? ($_ => $settings->{$_}) : () }
310			qw(path url_host url_scheme cookie bearer users)),
311			name => $name,
312			host => $host,
313			port => $service,
314			);
315
316			unless (AnyEvent::Socket::parse_address $host) {
317			my ($error, @addresses) = Socket::getaddrinfo ($host, undef, { socktype => Socket::SOCK_STREAM () });
318			!$error && @addresses
319			or die "Cannot resolve MCP bind host '$host': $error\n";
320
321			my ($error2, $address) = Socket::getnameinfo ($addresses[0]{addr}, Socket::NI_NUMERICHOST ());
322			!$error2 && length $address
323			or die "Cannot format MCP bind host '$host': $error2\n";
324
325			$kv{url_host} //= $host;
326			$kv{host} = $address;
327			}
328
329			unless (grep exists $kv{$_}, qw(cookie bearer users)) {
330			my $token = $self->credential ("cookie", $name);
331			@kv{qw(cookie bearer)} = ($token, $token);
332			}
333
334			%kv
335			}
336
337			sub http_url {
338			my ($self, $name, $bind, %options) = @_;
339
340			# A printed URL needs a credential that survives the next process.
341			my $stored = ref ($self)->new (file => $self->{file});
342			$stored->{section}{global}{secret} eq $self->{section}{global}{secret}
343			or die "MCP master secret is not persistently stored in $self->{file}\n";
344
345			require AnyEvent::MCP::Server::HTTP;
346			my $server = AnyEvent::MCP::Server::HTTP->new ($self->http_settings ($name, $bind), %options);
347			$server->url
348			}
349
350	root	1.1	sub url {
351			my ($self, $name, $username) = @_;
352
353			my $url = $self->{section}{"server $name"}{url}
354			or die "No URL configured for server '$name'\n";
355
356			$url =~ s/\{cookie\}/$self->credential ("cookie", $name, $username)/ge;
357
358			$url
359			}
360
361			1