# Net::POP3.pm
#
# Copyright (c) 1995-2004 Graham Barr <gbarr@pobox.com>. All rights reserved.
# This program is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.

package Net::POP3;

use strict;
use IO::Socket;
use vars qw(@ISA $VERSION $debug);
use Net::Cmd;
use Carp;
use Net::Config;

$VERSION = "2.30";

@ISA = qw(Net::Cmd IO::Socket::INET);


sub new {
  my $self = shift;
  my $type = ref($self) || $self;
  my ($host, %arg);
  if (@_ % 2) {
    $host = shift;
    %arg  = @_;
  }
  else {
    %arg  = @_;
    $host = delete $arg{Host};
  }
  my $hosts = defined $host ? [$host] : $NetConfig{pop3_hosts};
  my $obj;
  my @localport = exists $arg{ResvPort} ? (LocalPort => $arg{ResvPort}) : ();

  my $h;
  foreach $h (@{$hosts}) {
    $obj = $type->SUPER::new(
      PeerAddr => ($host = $h),
      PeerPort => $arg{Port} || 'pop3(110)',
      Proto => 'tcp',
      @localport,
      Timeout => defined $arg{Timeout}
      ? $arg{Timeout}
      : 120
      )
      and last;
  }

  return undef
    unless defined $obj;

  ${*$obj}{'net_pop3_host'} = $host;

  $obj->autoflush(1);
  $obj->debug(exists $arg{Debug} ? $arg{Debug} : undef);

  unless ($obj->response() == CMD_OK) {
    $obj->close();
    return undef;
  }

  ${*$obj}{'net_pop3_banner'} = $obj->message;

  $obj;
}


sub host {
  my $me = shift;
  ${*$me}{'net_pop3_host'};
}

##
## We don't want people sending me their passwords when they report problems
## now do we :-)
##


sub debug_text { $_[2] =~ /^(pass|rpop)/i ? "$1 ....\n" : $_[2]; }


sub login {
  @_ >= 1 && @_ <= 3 or croak 'usage: $pop3->login( USER, PASS )';
  my ($me, $user, $pass) = @_;

  if (@_ <= 2) {
    ($user, $pass) = $me->_lookup_credentials($user);
  }

  $me->user($user)
    and $me->pass($pass);
}


sub apop {
  @_ >= 1 && @_ <= 3 or croak 'usage: $pop3->apop( USER, PASS )';
  my ($me, $user, $pass) = @_;
  my $banner;
  my $md;

  if (eval { local $SIG{__DIE__}; require Digest::MD5 }) {
    $md = Digest::MD5->new();
  }
  elsif (eval { local $SIG{__DIE__}; require MD5 }) {
    $md = MD5->new();
  }
  else {
    carp "You need to install Digest::MD5 or MD5 to use the APOP command";
    return undef;
  }

  return undef
    unless ($banner = (${*$me}{'net_pop3_banner'} =~ /(<.*>)/)[0]);

  if (@_ <= 2) {
    ($user, $pass) = $me->_lookup_credentials($user);
  }

  $md->add($banner, $pass);

  return undef
    unless ($me->_APOP($user, $md->hexdigest));

  $me->_get_mailbox_count();
}


sub user {
  @_ == 2 or croak 'usage: $pop3->user( USER )';
  $_[0]->_USER($_[1]) ? 1 : undef;
}


sub pass {
  @_ == 2 or croak 'usage: $pop3->pass( PASS )';

  my ($me, $pass) = @_;

  return undef
    unless ($me->_PASS($pass));

  $me->_get_mailbox_count();
}


sub reset {
  @_ == 1 or croak 'usage: $obj->reset()';

  my $me = shift;

  return 0
    unless ($me->_RSET);

  if (defined ${*$me}{'net_pop3_mail'}) {
    local $_;
    foreach (@{${*$me}{'net_pop3_mail'}}) {
      delete $_->{'net_pop3_deleted'};
    }
  }
}


sub last {
  @_ == 1 or croak 'usage: $obj->last()';

  return undef
    unless $_[0]->_LAST && $_[0]->message =~ /(\d+)/;

  return $1;
}


sub top {
  @_ == 2 || @_ == 3 or croak 'usage: $pop3->top( MSGNUM [, NUMLINES ])';
  my $me = shift;

  return undef
    unless $me->_TOP($_[0], $_[1] || 0);

  $me->read_until_dot;
}


sub popstat {
  @_ == 1 or croak 'usage: $pop3->popstat()';
  my $me = shift;

  return ()
    unless $me->_STAT && $me->message =~ /(\d+)\D+(\d+)/;

  ($1 || 0, $2 || 0);
}


sub list {
  @_ == 1 || @_ == 2 or croak 'usage: $pop3->list( [ MSGNUM ] )';
  my $me = shift;

  return undef
    unless $me->_LIST(@_);

  if (@_) {
    $me->message =~ /\d+\D+(\d+)/;
    return $1 || undef;
  }

  my $info = $me->read_until_dot
    or return undef;

  my %hash = map { (/(\d+)\D+(\d+)/) } @$info;

  return \%hash;
}


sub get {
  @_ == 2 or @_ == 3 or croak 'usage: $pop3->get( MSGNUM [, FH ])';
  my $me = shift;

  return undef
    unless $me->_RETR(shift);

  $me->read_until_dot(@_);
}


sub getfh {
  @_ == 2 or croak 'usage: $pop3->getfh( MSGNUM )';
  my $me = shift;

  return unless $me->_RETR(shift);
  return $me->tied_fh;
}


sub delete {
  @_ == 2 or croak 'usage: $pop3->delete( MSGNUM )';
  my $me = shift;
  return 0 unless $me->_DELE(@_);
  ${*$me}{'net_pop3_deleted'} = 1;
}


sub uidl {
  @_ == 1 || @_ == 2 or croak 'usage: $pop3->uidl( [ MSGNUM ] )';
  my $me = shift;
  my $uidl;

  $me->_UIDL(@_)
    or return undef;
  if (@_) {
    $uidl = ($me->message =~ /\d+\s+([\041-\176]+)/)[0];
  }
  else {
    my $ref = $me->read_until_dot
      or return undef;
    my $ln;
    $uidl = {};
    foreach $ln (@$ref) {
      my ($msg, $uid) = $ln =~ /^\s*(\d+)\s+([\041-\176]+)/;
      $uidl->{$msg} = $uid;
    }
  }
  return $uidl;
}


sub ping {
  @_ == 2 or croak 'usage: $pop3->ping( USER )';
  my $me = shift;

  return () unless $me->_PING(@_) && $me->message =~ /(\d+)\D+(\d+)/;

  ($1 || 0, $2 || 0);
}


sub _lookup_credentials {
  my ($me, $user) = @_;

  require Net::Netrc;

       $user ||= eval { local $SIG{__DIE__}; (getpwuid($>))[0] }
    || $ENV{NAME}
    || $ENV{USER}
    || $ENV{LOGNAME};

  my $m = Net::Netrc->lookup(${*$me}{'net_pop3_host'}, $user);
  $m ||= Net::Netrc->lookup(${*$me}{'net_pop3_host'});

  my $pass = $m
    ? $m->password || ""
    : "";

  ($user, $pass);
}


sub _get_mailbox_count {
  my ($me) = @_;
  my $ret = ${*$me}{'net_pop3_count'} =
    ($me->message =~ /(\d+)\s+message/io) ? $1 : ($me->popstat)[0];

  $ret ? $ret : "0E0";
}


sub _STAT { shift->command('STAT'       )->response() == CMD_OK }
sub _LIST { shift->command('LIST',    @_)->response() == CMD_OK }
sub _RETR { shift->command('RETR', $_[0])->response() == CMD_OK }
sub _DELE { shift->command('DELE', $_[0])->response() == CMD_OK }
sub _NOOP { shift->command('NOOP'       )->response() == CMD_OK }
sub _RSET { shift->command('RSET'       )->response() == CMD_OK }
sub _QUIT { shift->command('QUIT'       )->response() == CMD_OK }
sub _TOP  { shift->command( 'TOP',    @_)->response() == CMD_OK }
sub _UIDL { shift->command('UIDL',    @_)->response() == CMD_OK }
sub _USER { shift->command('USER', $_[0])->response() == CMD_OK }
sub _PASS { shift->command('PASS', $_[0])->response() == CMD_OK }
sub _APOP { shift->command('APOP',    @_)->response() == CMD_OK }
sub _PING { shift->command('PING', $_[0])->response() == CMD_OK }
sub _RPOP { shift->command('RPOP', $_[0])->response() == CMD_OK }
sub _LAST { shift->command('LAST'       )->response() == CMD_OK }
sub _CAPA { shift->command('CAPA'       )->response() == CMD_OK }


sub quit {
  my $me = shift;

  $me->_QUIT;
  $me->close;
}


sub DESTROY {
  my $me = shift;

  if (defined fileno($me) and ${*$me}{'net_pop3_deleted'}) {
    $me->reset;
    $me->quit;
  }
}

##
## POP3 has weird responses, so we emulate them to look the same :-)
##


sub response {
  my $cmd  = shift;
  my $str  = $cmd->getline() or return undef;
  my $code = "500";

  $cmd->debug_print(0, $str)
    if ($cmd->debug);

  if ($str =~ s/^\+OK\s*//io) {
    $code = "200";
  }
  elsif ($str =~ s/^\+\s*//io) {
    $code = "300";
  }
  else {
    $str =~ s/^-ERR\s*//io;
  }

  ${*$cmd}{'net_cmd_resp'} = [$str];
  ${*$cmd}{'net_cmd_code'} = $code;

  substr($code, 0, 1);
}


sub capa {
  my $this = shift;
  my ($capa, %capabilities);

  # Fake a capability here
  $capabilities{APOP} = '' if ($this->banner() =~ /<.*>/);

  if ($this->_CAPA()) {
    $capabilities{CAPA} = 1;
    $capa = $this->read_until_dot();
    %capabilities = (%capabilities, map {/^\s*(\S+)\s*(.*)/} @$capa);
  }
  else {

    # Check AUTH for SASL capabilities
    if ($this->command('AUTH')->response() == CMD_OK) {
      my $mechanism = $this->read_until_dot();
      $capabilities{SASL} = join " ", map {m/([A-Z0-9_-]+)/} @{$mechanism};
    }
  }

  return ${*$this}{'net_pop3e_capabilities'} = \%capabilities;
}


sub capabilities {
  my $this = shift;

  ${*$this}{'net_pop3e_capabilities'} || $this->capa;
}


sub auth {
  my ($self, $username, $password) = @_;

  eval {
    require MIME::Base64;
    require Authen::SASL;
  } or $self->set_status(500, ["Need MIME::Base64 and Authen::SASL todo auth"]), return 0;

  my $capa       = $self->capa;
  my $mechanisms = $capa->{SASL} || 'CRAM-MD5';

  my $sasl;

  if (ref($username) and UNIVERSAL::isa($username, 'Authen::SASL')) {
    $sasl = $username;
    my $user_mech = $sasl->mechanism || '';
    my @user_mech = split(/\s+/, $user_mech);
    my %user_mech;
    @user_mech{@user_mech} = ();

    my @server_mech = split(/\s+/, $mechanisms);
    my @mech = @user_mech
      ? grep { exists $user_mech{$_} } @server_mech
      : @server_mech;
    unless (@mech) {
      $self->set_status(
        500,
        [ 'Client SASL mechanisms (',
          join(', ', @user_mech),
          ') do not match the SASL mechnism the server announces (',
          join(', ', @server_mech), ')',
        ]
      );
      return 0;
    }

    $sasl->mechanism(join(" ", @mech));
  }
  else {
    die "auth(username, password)" if not length $username;
    $sasl = Authen::SASL->new(
      mechanism => $mechanisms,
      callback  => {
        user     => $username,
        pass     => $password,
        authname => $username,
      }
    );
  }

  # We should probably allow the user to pass the host, but I don't
  # currently know and SASL mechanisms that are used by smtp that need it
  my ($hostname) = split /:/, ${*$self}{'net_pop3_host'};
  my $client = eval { $sasl->client_new('pop', $hostname, 0) };

  unless ($client) {
    my $mech = $sasl->mechanism;
    $self->set_status(
      500,
      [ " Authen::SASL failure: $@",
        '(please check if your local Authen::SASL installation',
        "supports mechanism '$mech'"
      ]
    );
    return 0;
  }

  my ($token) = $client->client_start
    or do {
    my $mech = $client->mechanism;
    $self->set_status(
      500,
      [ ' Authen::SASL failure:  $client->client_start ',
        "mechanism '$mech' hostname #$hostname#",
        $client->error
      ]
    );
    return 0;
    };

  # We don't support sasl mechanisms that encrypt the socket traffic.
  # todo that we would really need to change the ISA hierarchy
  # so we don't inherit from IO::Socket, but instead hold it in an attribute

  my @cmd = ("AUTH", $client->mechanism);
  my $code;

  push @cmd, MIME::Base64::encode_base64($token, '')
    if defined $token and length $token;

  while (($code = $self->command(@cmd)->response()) == CMD_MORE) {

    my ($token) = $client->client_step(MIME::Base64::decode_base64(($self->message)[0])) or do {
      $self->set_status(
        500,
        [ ' Authen::SASL failure:  $client->client_step ',
          "mechanism '", $client->mechanism, " hostname #$hostname#, ",
          $client->error
        ]
      );
      return 0;
    };

    @cmd = (MIME::Base64::encode_base64(defined $token ? $token : '', ''));
  }

  $code == CMD_OK;
}


sub banner {
  my $this = shift;

  return ${*$this}{'net_pop3_banner'};
}

1;

__END__

=head1 NAME

Net::POP3 - Post Office Protocol 3 Client class (RFC1939)

=head1 SYNOPSIS

    use Net::POP3;

    # Constructors
    $pop = Net::POP3->new('pop3host');
    $pop = Net::POP3->new('pop3host', Timeout => 60);

    if ($pop->login($username, $password) > 0) {
      my $msgnums = $pop->list; # hashref of msgnum => size
      foreach my $msgnum (keys %$msgnums) {
        my $msg = $pop->get($msgnum);
        print @$msg;
        $pop->delete($msgnum);
      }
    }

    $pop->quit;

=head1 DESCRIPTION

This module implements a client interface to the POP3 protocol, enabling
a perl5 application to talk to POP3 servers. This documentation assumes
that you are familiar with the POP3 protocol described in RFC1939.

A new Net::POP3 object must be created with the I<new> method. Once
this has been done, all POP3 commands are accessed via method calls
on the object.

=head1 CONSTRUCTOR

=over 4

=item new ( [ HOST ] [, OPTIONS ] )

This is the constructor for a new Net::POP3 object. C<HOST> is the
name of the remote host to which an POP3 connection is required.

C<HOST> is optional. If C<HOST> is not given then it may instead be
passed as the C<Host> option described below. If neither is given then
the C<POP3_Hosts> specified in C<Net::Config> will be used.

C<OPTIONS> are passed in a hash like fashion, using key and value pairs.
Possible options are:

B<Host> - POP3 host to connect to. It may be a single scalar, as defined for
the C<PeerAddr> option in L<IO::Socket::INET>, or a reference to
an array with hosts to try in turn. The L</host> method will return the value
which was used to connect to the host.

B<ResvPort> - If given then the socket for the C<Net::POP3> object
will be bound to the local port given using C<bind> when the socket is
created.

B<Timeout> - Maximum time, in seconds, to wait for a response from the
POP3 server (default: 120)

B<Debug> - Enable debugging information

=back

=head1 METHODS

Unless otherwise stated all methods return either a I<true> or I<false>
value, with I<true> meaning that the operation was a success. When a method
states that it returns a value, failure will be returned as I<undef> or an
empty list.

=over 4

=item auth ( USERNAME, PASSWORD )

Attempt SASL authentication.

=item user ( USER )

Send the USER command.

=item pass ( PASS )

Send the PASS command. Returns the number of messages in the mailbox.

=item login ( [ USER [, PASS ]] )

Send both the USER and PASS commands. If C<PASS> is not given the
C<Net::POP3> uses C<Net::Netrc> to lookup the password using the host
and username. If the username is not specified then the current user name
will be used.

Returns the number of messages in the mailbox. However if there are no
messages on the server the string C<"0E0"> will be returned. This is
will give a true value in a boolean context, but zero in a numeric context.

If there was an error authenticating the user then I<undef> will be returned.

=item apop ( [ USER [, PASS ]] )

Authenticate with the server identifying as C<USER> with password C<PASS>.
Similar to L</login>, but the password is not sent in clear text.

To use this method you must have the Digest::MD5 or the MD5 module installed,
otherwise this method will return I<undef>.

=item banner ()

Return the sever's connection banner

=item capa ()

Return a reference to a hash of the capabilities of the server.  APOP
is added as a pseudo capability.  Note that I've been unable to
find a list of the standard capability values, and some appear to
be multi-word and some are not.  We make an attempt at intelligently
parsing them, but it may not be correct.

=item  capabilities ()

Just like capa, but only uses a cache from the last time we asked
the server, so as to avoid asking more than once.

=item top ( MSGNUM [, NUMLINES ] )

Get the header and the first C<NUMLINES> of the body for the message
C<MSGNUM>. Returns a reference to an array which contains the lines of text
read from the server.

=item list ( [ MSGNUM ] )

If called with an argument the C<list> returns the size of the message
in octets.

If called without arguments a reference to a hash is returned. The
keys will be the C<MSGNUM>'s of all undeleted messages and the values will
be their size in octets.

=item get ( MSGNUM [, FH ] )

Get the message C<MSGNUM> from the remote mailbox. If C<FH> is not given
then get returns a reference to an array which contains the lines of
text read from the server. If C<FH> is given then the lines returned
from the server are printed to the filehandle C<FH>.

=item getfh ( MSGNUM )

As per get(), but returns a tied filehandle.  Reading from this
filehandle returns the requested message.  The filehandle will return
EOF at the end of the message and should not be reused.

=item last ()

Returns the highest C<MSGNUM> of all the messages accessed.

=item popstat ()

Returns a list of two elements. These are the number of undeleted
elements and the size of the mbox in octets.

=item ping ( USER )

Returns a list of two elements. These are the number of new messages
and the total number of messages for C<USER>.

=item uidl ( [ MSGNUM ] )

Returns a unique identifier for C<MSGNUM> if given. If C<MSGNUM> is not
given C<uidl> returns a reference to a hash where the keys are the
message numbers and the values are the unique identifiers.

=item delete ( MSGNUM )

Mark message C<MSGNUM> to be deleted from the remote mailbox. All messages
that are marked to be deleted will be removed from the remote mailbox
when the server connection closed.

=item reset ()

Reset the status of the remote POP3 server. This includes resetting the
status of all messages to not be deleted.

=item quit ()

Quit and close the connection to the remote POP3 server. Any messages marked
as deleted will be deleted from the remote mailbox.

=back

=head1 NOTES

If a C<Net::POP3> object goes out of scope before C<quit> method is called
then the C<reset> method will called before the connection is closed. This
means that any messages marked to be deleted will not be.

=head1 SEE ALSO

L<Net::Netrc>,
L<Net::Cmd>

=head1 AUTHOR

Graham Barr <gbarr@pobox.com>

=head1 COPYRIGHT

Copyright (c) 1995-2003 Graham Barr. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=cut