#!/usr/bin/env perl
#***************************************************************************
#                                  _   _ ____  _
#  Project                     ___| | | |  _ \| |
#                             / __| | | | |_) | |
#                            | (__| |_| |  _ <| |___
#                             \___|\___/|_| \_\_____|
#
# Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at https://curl.se/docs/copyright.html.
#
# You may opt to use, copy, modify, merge, publish, distribute and/or sell
# copies of the Software, and permit persons to whom the Software is
# furnished to do so, under the terms of the COPYING file.
#
# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
# KIND, either express or implied.
#
# SPDX-License-Identifier: curl
#
###########################################################################

# This is a server designed for the curl test suite.
#
# In December 2009 we started remaking the server to support more protocols
# that are similar in spirit. Like POP3, IMAP and SMTP in addition to the FTP
# it already supported since a long time. Note that it still only supports one
# protocol per invoke. You need to start multiple servers to support multiple
# protocols simultaneously.
#
# It is meant to exercise curl, it is not meant to be a fully working
# or even overly standard compliant server.
#
# You may optionally specify port on the command line, otherwise it
# defaults to port 8921.
#
# All socket/network/TCP related stuff is done by the 'sockfilt' program.
#

use strict;
use warnings;

BEGIN {
    push(@INC, $ENV{'srcdir'}) if(defined $ENV{'srcdir'});
    push(@INC, ".");
}

use IPC::Open2;
use Digest::MD5;
use File::Basename;
use Time::HiRes;

use directories;

use getpart qw(
    getpartattr
    getpart
    loadtest
    );

use processhelp;

use serverhelp qw(
    logmsg
    $logfile
    servername_str
    server_pidfilename
    server_logfilename
    server_exe_args
    mainsockf_pidfilename
    mainsockf_logfilename
    datasockf_pidfilename
    datasockf_logfilename
    );

use globalconfig qw(
    $SERVERCMD
    $LOCKDIR
    );

#**********************************************************************
# global vars...
#
my $verbose = 0;    # set to 1 for debugging
my $idstr = "";     # server instance string
my $idnum = 1;      # server instance number
my $ipvnum = 4;     # server IPv number (4 or 6)
my $proto = 'ftp';  # default server protocol
my $srcdir;         # directory where ftpserver.pl is located
my $srvrname;       # server name for presentation purposes
my $cwd_testno;     # test case numbers extracted from CWD command
my $testno = 0;     # test case number (read from server.cmd)
my $path   = '.';
my $logdir = $path .'/log';
my $piddir;

#**********************************************************************
# global vars used for server address and primary listener port
#
my $port = 8921;               # default primary listener port
my $listenaddr = '127.0.0.1';  # default address for listener port

#**********************************************************************
# global vars used for filenames
#
my $PORTFILE = "ftpserver.port"; # server port filename
my $portfile;           # server port file path
my $pidfile;            # server pid filename
my $mainsockf_pidfile;  # pid file for primary connection sockfilt process
my $mainsockf_logfile;  # log file for primary connection sockfilt process
my $datasockf_pidfile;  # pid file for secondary connection sockfilt process
my $datasockf_logfile;  # log file for secondary connection sockfilt process

#**********************************************************************
# global vars used for server logs advisor read lock handling
#
my $serverlogs_lockfile;
my $serverlogslocked = 0;

#**********************************************************************
# global vars used for child processes PID tracking
#
my $sfpid;        # PID for primary connection sockfilt process
my $slavepid;     # PID for secondary connection sockfilt process

#**********************************************************************
# global typeglob filehandle vars to read/write from/to sockfilters
#
local *SFREAD;    # used to read from primary connection
local *SFWRITE;   # used to write to primary connection
local *DREAD;     # used to read from secondary connection
local *DWRITE;    # used to write to secondary connection

my $sockfilt_timeout = 5;  # default timeout for sockfilter eXsysreads

#**********************************************************************
# global vars which depend on server protocol selection
#
my %commandfunc;   # protocol command specific function callbacks
my %displaytext;   # text returned to client before callback runs

#**********************************************************************
# global vars customized for each test from the server commands file
#
my $ctrldelay;     # set if server should throttle ctrl stream
my $datadelay;     # set if server should throttle data stream
my $retrweirdo;    # set if FTP server should use RETRWEIRDO
my $retrnosize;    # set if FTP server should use RETRNOSIZE
my $retrsize;      # set if FTP server should use RETRSIZE
my $pasvbadip;     # set if FTP server should use PASVBADIP
my $nosave;        # set if FTP server should not save uploaded data
my $nodataconn;    # set if FTP srvr does not establish or accepts data channel
my $nodataconn425; # set if FTP srvr does not establish data ch and replies 425
my $nodataconn421; # set if FTP srvr does not establish data ch and replies 421
my $nodataconn150; # set if FTP srvr does not establish data ch and replies 150
my $storeresp;
my $postfetch;
my @capabilities;  # set if server supports capability commands
my @auth_mechs;    # set if server supports authentication commands
my %fulltextreply; #
my %commandreply;  #
my %customcount;   #
my %delayreply;    #

#**********************************************************************
# global variables for to test FTP wildcardmatching or other test that
# need flexible LIST responses.. and corresponding files.
# $ftptargetdir is keeping the fake "name" of LIST directory.
#
my $ftplistparserstate;
my $ftptargetdir = "";

#**********************************************************************
# global variables used when running an FTP server to keep state info
# relative to the secondary or data sockfilt process. Values of these
# variables should only be modified using datasockf_state() sub, given
# that they are closely related and relationship is a bit awkward.
#
my $datasockf_state = 'STOPPED'; # see datasockf_state() sub
my $datasockf_mode = 'none';     # ['none','active','passive']
my $datasockf_runs = 'no';       # ['no','yes']
my $datasockf_conn = 'no';       # ['no','yes']

#**********************************************************************
# global vars used for signal handling
#
my $got_exit_signal = 0; # set if program should finish execution ASAP

#**********************************************************************
# Mail related definitions
#
my $TEXT_PASSWORD = "secret";
my $POP3_TIMESTAMP = "<1972.987654321\@curl>";

#**********************************************************************
# exit_signal_handler is triggered to indicate that the program
# should finish its execution in a controlled way as soon as possible.
# For now, program also terminates from within this handler.
#
sub exit_signal_handler {
    my $signame = shift;
    # For now, mimic old behavior.
    killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose);
    unlink($pidfile);
    unlink($portfile);
    if($serverlogslocked) {
        $serverlogslocked = 0;
        clear_advisor_read_lock($serverlogs_lockfile);
    }
    exit;
}

sub ftpmsg {
  # append to the server.input file
  open(my $input, ">>", "$logdir/server$idstr.input") ||
    logmsg "failed to open $logdir/server$idstr.input\n";

  print $input @_;
  close($input);

  # use this, open->print->close system only to make the file
  # open as little as possible, to make the test suite run
  # better on Windows/Cygwin
}

#**********************************************************************
# eXsysread is a wrapper around perl's sysread() function. This repeats
# the call to sysread() until it has actually read the complete number
# of requested bytes or an unrecoverable condition occurs.
# On success returns a positive value, the number of bytes requested.
# On failure or timeout returns zero.
#
sub eXsysread {
    my $FH      = shift;
    my $scalar  = shift;
    my $nbytes  = shift;
    my $timeout = shift; # A zero timeout disables eXsysread() time limit
    #
    my $time_limited = 0;
    my $timeout_rest = 0;
    my $start_time = 0;
    my $nread  = 0;
    my $rc;

    $$scalar = "";

    if((not defined $nbytes) || ($nbytes < 1)) {
        logmsg "Error: eXsysread() failure: " .
               "length argument must be positive\n";
        return 0;
    }
    if((not defined $timeout) || ($timeout < 0)) {
        logmsg "Error: eXsysread() failure: " .
               "timeout argument must be zero or positive\n";
        return 0;
    }
    if($timeout > 0) {
        # caller sets eXsysread() time limit
        $time_limited = 1;
        $timeout_rest = $timeout;
        $start_time = int(time());
    }

    while($nread < $nbytes) {
        if($time_limited) {
            eval {
                local $SIG{ALRM} = sub { die "alarm\n"; };
                alarm $timeout_rest;
                $rc = sysread($FH, $$scalar, $nbytes - $nread, $nread);
                alarm 0;
            };
            $timeout_rest = $timeout - (int(time()) - $start_time);
            if($timeout_rest < 1) {
                logmsg "Error: eXsysread() failure: timed out\n";
                return 0;
            }
        }
        else {
            $rc = sysread($FH, $$scalar, $nbytes - $nread, $nread);
        }
        if($got_exit_signal) {
            logmsg "Error: eXsysread() failure: signalled to die\n";
            return 0;
        }
        if(not defined $rc) {
            if($!{EINTR}) {
                logmsg "Warning: retrying sysread() interrupted system call\n";
                next;
            }
            if($!{EAGAIN}) {
                logmsg "Warning: retrying sysread() due to EAGAIN\n";
                next;
            }
            if($!{EWOULDBLOCK}) {
                logmsg "Warning: retrying sysread() due to EWOULDBLOCK\n";
                next;
            }
            logmsg "Error: sysread() failure: $!\n";
            return 0;
        }
        if($rc < 0) {
            logmsg "Error: sysread() failure: returned negative value $rc\n";
            return 0;
        }
        if($rc == 0) {
            logmsg "Error: sysread() failure: read zero bytes\n";
            return 0;
        }
        $nread += $rc;
    }
    return $nread;
}

#**********************************************************************
# read_mainsockf attempts to read the given amount of output from the
# sockfilter which is in use for the main or primary connection. This
# reads untranslated sockfilt lingo which may hold data read from the
# main or primary socket. On success returns 1, otherwise zero.
#
sub read_mainsockf {
    my $scalar  = shift;
    my $nbytes  = shift;
    my $timeout = shift; # Optional argument, if zero blocks indefinitely
    my $FH = \*SFREAD;

    if(not defined $timeout) {
        $timeout = $sockfilt_timeout + ($nbytes >> 12);
    }
    if(eXsysread($FH, $scalar, $nbytes, $timeout) != $nbytes) {
        my ($fcaller, $lcaller) = (caller)[1,2];
        logmsg "Error: read_mainsockf() failure at $fcaller " .
               "line $lcaller. Due to eXsysread() failure\n";
        return 0;
    }
    return 1;
}

#**********************************************************************
# read_datasockf attempts to read the given amount of output from the
# sockfilter which is in use for the data or secondary connection. This
# reads untranslated sockfilt lingo which may hold data read from the
# data or secondary socket. On success returns 1, otherwise zero.
#
sub read_datasockf {
    my $scalar = shift;
    my $nbytes = shift;
    my $timeout = shift; # Optional argument, if zero blocks indefinitely
    my $FH = \*DREAD;

    if(not defined $timeout) {
        $timeout = $sockfilt_timeout + ($nbytes >> 12);
    }
    if(eXsysread($FH, $scalar, $nbytes, $timeout) != $nbytes) {
        my ($fcaller, $lcaller) = (caller)[1,2];
        logmsg "Error: read_datasockf() failure at $fcaller " .
               "line $lcaller. Due to eXsysread() failure\n";
        return 0;
    }
    return 1;
}

sub sysread_or_die {
    my $FH     = shift;
    my $scalar = shift;
    my $length = shift;
    my $fcaller;
    my $lcaller;
    my $result;

    $result = sysread($$FH, $$scalar, $length);

    if(not defined $result) {
        ($fcaller, $lcaller) = (caller)[1,2];
        logmsg "Failed to read input\n";
        logmsg "Error: $srvrname server, sysread error: $!\n";
        logmsg "Exited from sysread_or_die() at $fcaller " .
               "line $lcaller. $srvrname server, sysread error: $!\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose);
        unlink($pidfile);
        unlink($portfile);
        if($serverlogslocked) {
            $serverlogslocked = 0;
            clear_advisor_read_lock($serverlogs_lockfile);
        }
        exit;
    }
    elsif($result == 0) {
        ($fcaller, $lcaller) = (caller)[1,2];
        logmsg "Failed to read input\n";
        logmsg "Error: $srvrname server, read zero\n";
        logmsg "Exited from sysread_or_die() at $fcaller " .
               "line $lcaller. $srvrname server, read zero\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose);
        unlink($pidfile);
        unlink($portfile);
        if($serverlogslocked) {
            $serverlogslocked = 0;
            clear_advisor_read_lock($serverlogs_lockfile);
        }
        exit;
    }

    return $result;
}

sub startsf {
    my @mainsockfcmd = (server_exe_args('sockfilt'),
        "--ipv$ipvnum",
        "--port", $port,
        "--pidfile", $mainsockf_pidfile,
        "--portfile", $portfile,
        "--logfile", $mainsockf_logfile);
    $sfpid = open2(*SFREAD, *SFWRITE, @mainsockfcmd);

    print STDERR "@mainsockfcmd\n" if($verbose);

    print SFWRITE "PING\n";
    my $pong;
    sysread_or_die(\*SFREAD, \$pong, 5);

    if($pong !~ /^PONG/) {
        logmsg "Failed sockfilt command: @mainsockfcmd\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose);
        unlink($pidfile);
        unlink($portfile);
        if($serverlogslocked) {
            $serverlogslocked = 0;
            clear_advisor_read_lock($serverlogs_lockfile);
        }
        die "Failed to start sockfilt!";
    }
}

#**********************************************************************
# Returns the given test's reply data
#
sub getreplydata {
    my ($num) = @_;
    my $testpart = "";

    $num =~ s/^([^0-9]*)//;
    if($num > 10000) {
       $testpart = $num % 10000;
    }

    my @data = getpart("reply", "data$testpart");
    if((!@data) && ($testpart ne "")) {
        @data = getpart("reply", "data");
    }

    return @data;
}

sub sockfilt {
    my $l;
    foreach $l (@_) {
        printf SFWRITE "DATA\n%04x\n", length($l);
        print SFWRITE $l;
    }
}

sub sockfiltsecondary {
    my $l;
    foreach $l (@_) {
        printf DWRITE "DATA\n%04x\n", length($l);
        print DWRITE $l;
    }
}

#**********************************************************************
# Send data to the client on the control stream, which happens to be plain
# stdout.
#
sub sendcontrol {
    if(!$ctrldelay) {
        # spit it all out at once
        sockfilt @_;
    }
    else {
        my $a = join("", @_);
        my @a = split("", $a);

        for(@a) {
            sockfilt $_;
            Time::HiRes::sleep($ctrldelay);
        }
    }
    my $log;
    foreach $log (@_) {
        my $l = $log;
        $l =~ s/\r/[CR]/g;
        $l =~ s/\n/[LF]/g;
        logmsg "> \"$l\"\n";
    }
}

#**********************************************************************
# Send data to the FTP client on the data stream when data connection
# is actually established. Given that this sub should only be called
# when a data connection is supposed to be established, calling this
# without a data connection is an indication of weak logic somewhere.
#
sub senddata {
    my $l;
    if($datasockf_conn eq 'no') {
        logmsg "WARNING: Detected data sending attempt without DATA channel\n";
        foreach $l (@_) {
            logmsg "WARNING: Data swallowed: $l\n"
        }
        return;
    }

    foreach $l (@_) {
        if(!$datadelay) {
            # spit it all out at once
            sockfiltsecondary $l;
        }
        else {
            # pause between each byte
            for (split(//,$l)) {
                sockfiltsecondary $_;
                Time::HiRes::sleep($datadelay);
            }
        }
    }
}

#**********************************************************************
# protocolsetup initializes the 'displaytext' and 'commandfunc' hashes
# for the given protocol. References to protocol command callbacks are
# stored in 'commandfunc' hash, and text which is returned to the
# client before the command callback runs is stored in 'displaytext'.
#
sub protocolsetup {
    my $proto = $_[0];

    if($proto eq 'ftp') {
        %commandfunc = (
            'PORT' => \&PORT_ftp,
            'EPRT' => \&PORT_ftp,
            'LIST' => \&LIST_ftp,
            'NLST' => \&NLST_ftp,
            'PASV' => \&PASV_ftp,
            'CWD'  => \&CWD_ftp,
            'PWD'  => \&PWD_ftp,
            'EPSV' => \&PASV_ftp,
            'RETR' => \&RETR_ftp,
            'SIZE' => \&SIZE_ftp,
            'REST' => \&REST_ftp,
            'STOR' => \&STOR_ftp,
            'APPE' => \&STOR_ftp, # append looks like upload
            'MDTM' => \&MDTM_ftp,
        );
        %displaytext = (
            'USER' => '331 We are happy you popped in!',
            'PASS' => '230 Welcome you silly person',
            'PORT' => '200 You said PORT - I say FINE',
            'TYPE' => '200 I modify TYPE as you wanted',
            'LIST' => '150 here comes a directory',
            'NLST' => '150 here comes a directory',
            'CWD'  => '250 CWD command successful.',
            'SYST' => '215 UNIX Type: L8', # fake something
            'QUIT' => '221 bye bye baby', # reply something
            'MKD'  => '257 Created your requested directory',
            'REST' => '350 Yeah yeah we set it there for you',
            'DELE' => '200 OK OK OK whatever you say',
            'RNFR' => '350 Received your order. Please provide more',
            'RNTO' => '250 Ok, thanks. File renaming completed.',
            'NOOP' => '200 Yes, I\'m very good at doing nothing.',
            'PBSZ' => '500 PBSZ not implemented',
            'PROT' => '500 PROT not implemented',
            'welcome' => join("",
            '220-        _   _ ____  _'."\r\n",
            '220-    ___| | | |  _ \| |'."\r\n",
            '220-   / __| | | | |_) | |'."\r\n",
            '220-  | (__| |_| |  _ {| |___'."\r\n",
            '220    \___|\___/|_| \_\_____|'."\r\n")
        );
    }
    elsif($proto eq 'pop3') {
        %commandfunc = (
            'APOP' => \&APOP_pop3,
            'AUTH' => \&AUTH_pop3,
            'CAPA' => \&CAPA_pop3,
            'DELE' => \&DELE_pop3,
            'LIST' => \&LIST_pop3,
            'NOOP' => \&NOOP_pop3,
            'PASS' => \&PASS_pop3,
            'QUIT' => \&QUIT_pop3,
            'RETR' => \&RETR_pop3,
            'RSET' => \&RSET_pop3,
            'STAT' => \&STAT_pop3,
            'TOP'  => \&TOP_pop3,
            'UIDL' => \&UIDL_pop3,
            'USER' => \&USER_pop3,
        );
        %displaytext = (
            'welcome' => join("",
            '        _   _ ____  _'."\r\n",
            '    ___| | | |  _ \| |'."\r\n",
            '   / __| | | | |_) | |'."\r\n",
            '  | (__| |_| |  _ {| |___'."\r\n",
            '   \___|\___/|_| \_\_____|'."\r\n",
            '+OK curl POP3 server ready to serve '."\r\n")
        );
    }
    elsif($proto eq 'imap') {
        %commandfunc = (
            'APPEND'     => \&APPEND_imap,
            'CAPABILITY' => \&CAPABILITY_imap,
            'CHECK'      => \&CHECK_imap,
            'CLOSE'      => \&CLOSE_imap,
            'COPY'       => \&COPY_imap,
            'CREATE'     => \&CREATE_imap,
            'DELETE'     => \&DELETE_imap,
            'EXAMINE'    => \&EXAMINE_imap,
            'EXPUNGE'    => \&EXPUNGE_imap,
            'FETCH'      => \&FETCH_imap,
            'LIST'       => \&LIST_imap,
            'LSUB'       => \&LSUB_imap,
            'LOGIN'      => \&LOGIN_imap,
            'LOGOUT'     => \&LOGOUT_imap,
            'NOOP'       => \&NOOP_imap,
            'RENAME'     => \&RENAME_imap,
            'SEARCH'     => \&SEARCH_imap,
            'SELECT'     => \&SELECT_imap,
            'STATUS'     => \&STATUS_imap,
            'STORE'      => \&STORE_imap,
            'UID'        => \&UID_imap,
            'IDLE'       => \&IDLE_imap,
        );
        %displaytext = (
            'welcome' => join("",
            '        _   _ ____  _'."\r\n",
            '    ___| | | |  _ \| |'."\r\n",
            '   / __| | | | |_) | |'."\r\n",
            '  | (__| |_| |  _ {| |___'."\r\n",
            '   \___|\___/|_| \_\_____|'."\r\n",
            '* OK curl IMAP server ready to serve'."\r\n")
        );
    }
    elsif($proto eq 'smtp') {
        %commandfunc = (
            'DATA' => \&DATA_smtp,
            'EHLO' => \&EHLO_smtp,
            'EXPN' => \&EXPN_smtp,
            'HELO' => \&HELO_smtp,
            'HELP' => \&HELP_smtp,
            'MAIL' => \&MAIL_smtp,
            'NOOP' => \&NOOP_smtp,
            'RSET' => \&RSET_smtp,
            'RCPT' => \&RCPT_smtp,
            'VRFY' => \&VRFY_smtp,
            'QUIT' => \&QUIT_smtp,
        );
        %displaytext = (
            'welcome' => join("",
            '220-        _   _ ____  _'."\r\n",
            '220-    ___| | | |  _ \| |'."\r\n",
            '220-   / __| | | | |_) | |'."\r\n",
            '220-  | (__| |_| |  _ {| |___'."\r\n",
            '220    \___|\___/|_| \_\_____|'."\r\n")
        );
    }
}

# Perform the disconnect handshake with sockfilt on the secondary connection
# (the only connection we actively disconnect).
# This involves waiting for the disconnect acknowledgment after the DISC
# command, while throwing away anything else that might come in before
# that.
sub disc_handshake {
    print DWRITE "DISC\n";
    my $line;
    my $nr;
    while(5 == ($nr = sysread DREAD, $line, 5)) {
        if($line eq "DATA\n") {
            # Must read the data bytes to stay in sync
            my $i;
            sysread DREAD, $i, 5;

            my $size = 0;
            if($i =~ /^([0-9a-fA-F]{4})\n/) {
                $size = hex($1);
            }

            logmsg "> Throwing away $size bytes on closed connection\n";
            read_datasockf(\$line, $size);
        }
        elsif($line eq "DISC\n") {
            logmsg "Fancy that; client wants to DISC, too\n";
            printf DWRITE "ACKD\n";
        }
        elsif($line eq "ACKD\n") {
            # Got the ack we were waiting for
            last;
        }
        else {
            logmsg "Ignoring: $line";
            # sockfilt should not be sending us any other commands
        }
    }
    if(!defined($nr)) {
        logmsg "Error: pipe read error ($!) while waiting for ACKD";
    }
    elsif($nr <= 0) {
        logmsg "Error: pipe EOF while waiting for ACKD";
    }
}

sub close_dataconn {
    my ($closed) = @_; # non-zero if already disconnected

    my $datapid = processexists($datasockf_pidfile);

    logmsg "=====> Closing $datasockf_mode DATA connection...\n";

    if(!$closed) {
        if($datapid > 0) {
            logmsg "Server disconnects $datasockf_mode DATA connection\n";
            disc_handshake();
            logmsg "Server disconnected $datasockf_mode DATA connection\n";
        }
        else {
            logmsg "Server finds $datasockf_mode DATA connection already ".
                   "disconnected\n";
        }
    }
    else {
        logmsg "Server knows $datasockf_mode DATA connection is already ".
               "disconnected\n";
    }

    if($datapid > 0) {
        logmsg "DATA sockfilt for $datasockf_mode data channel quits ".
               "(pid $datapid)\n";
        print DWRITE "QUIT\n";
        pidwait($datapid, 0);
        unlink($datasockf_pidfile) if(-f $datasockf_pidfile);
        logmsg "DATA sockfilt for $datasockf_mode data channel quit ".
               "(pid $datapid)\n";
    }
    else {
        logmsg "DATA sockfilt for $datasockf_mode data channel already ".
               "dead\n";
    }

    logmsg "=====> Closed $datasockf_mode DATA connection\n";

    datasockf_state('STOPPED');
}

################
################ SMTP commands
################

# The type of server (SMTP or ESMTP)
my $smtp_type;

# The client (which normally contains the test number)
my $smtp_client;

sub EHLO_smtp {
    my ($client) = @_;
    my @data;

    # TODO: Get the IP address of the client connection to use in the
    # EHLO response when the client does not specify one but for now use
    # 127.0.0.1
    if(!$client) {
        $client = "[127.0.0.1]";
    }

    # Set the server type to ESMTP
    $smtp_type = "ESMTP";

    # Calculate the EHLO response
    push @data, "$smtp_type pingpong test server Hello $client";

    if((@capabilities) || (@auth_mechs)) {
        my $mechs;

        for my $c (@capabilities) {
            push @data, $c;
        }

        for my $am (@auth_mechs) {
            if(!$mechs) {
                $mechs = $am;
            }
            else {
                $mechs .= " $am";
            }
        }

        if($mechs) {
            push @data, "AUTH $mechs";
        }
    }

    # Send the EHLO response
    for(my $i = 0; $i < @data; $i++) {
        my $d = $data[$i];

        if($i < @data - 1) {
            sendcontrol "250-$d\r\n";
        }
        else {
            sendcontrol "250 $d\r\n";
        }
    }

    # Store the client (as it may contain the test number)
    $smtp_client = $client;

    return 0;
}

sub HELO_smtp {
    my ($client) = @_;

    # TODO: Get the IP address of the client connection to use in the HELO
    # response when the client does not specify one but for now use 127.0.0.1
    if(!$client) {
        $client = "[127.0.0.1]";
    }

    # Set the server type to SMTP
    $smtp_type = "SMTP";

    # Send the HELO response
    sendcontrol "250 $smtp_type pingpong test server Hello $client\r\n";

    # Store the client (as it may contain the test number)
    $smtp_client = $client;

    return 0;
}

sub MAIL_smtp {
    my ($args) = @_;

    logmsg "MAIL_smtp got $args\n";

    if(!$args) {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    else {
        my $from;
        my $size;
        my $smtputf8 = grep /^SMTPUTF8$/, @capabilities;
        my @elements = split(/ /, $args);

        # Get the FROM and SIZE parameters
        for my $e (@elements) {
            if($e =~ /^FROM:(.*)$/) {
                $from = $1;
            }
            elsif($e =~ /^SIZE=(\d+)$/) {
                $size = $1;
            }
        }

        # this server does not "validate" MAIL FROM addresses
        if(length($from)) {
            my @found;
            my $valid = 1;

            # Check the capabilities for SIZE and if the specified size is
            # greater than the message size then reject it
            if(@found = grep /^SIZE (\d+)$/, @capabilities) {
                if($found[0] =~ /^SIZE (\d+)$/) {
                    if($size > $1) {
                        $valid = 0;
                    }
                }
            }

            if(!$valid) {
                sendcontrol "552 Message size too large\r\n";
            }
            else {
                sendcontrol "250 Sender OK\r\n";
            }
        }
        else {
            sendcontrol "501 Invalid address\r\n";
        }
    }

    return 0;
}

sub RCPT_smtp {
    my ($args) = @_;

    logmsg "RCPT_smtp got $args\n";

    # Get the TO parameter
    if($args !~ /^TO:(.*)/) {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    else {
        my $smtputf8 = grep /^SMTPUTF8$/, @capabilities;
        my $to = $1;

        # Validate the to address (only a valid email address inside <> is
        # allowed, such as <user@example.com>)
        if((!$smtputf8 && $to =~
             /^<([a-zA-Z0-9._%+-]+)\@(([a-zA-Z0-9-]+)\.)+([a-zA-Z]{2,4})>$/) ||
           ($smtputf8 && $to =~
             /^<([a-zA-Z0-9\x{80}-\x{ff}._%+-]+)\@(([a-zA-Z0-9\x{80}-\x{ff}-]+)\.)+([a-zA-Z]{2,4})>$/)) {
            sendcontrol "250 Recipient OK\r\n";
        }
        else {
            sendcontrol "501 Invalid address\r\n";
        }
    }

    return 0;
}

sub DATA_smtp {
    my ($args) = @_;

    if($args) {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    elsif($smtp_client !~ /^(\d*)$/) {
        sendcontrol "501 Invalid arguments\r\n";
    }
    else {
        sendcontrol "354 Show me the mail\r\n";

        my $testno = $smtp_client;
        my $filename = "$logdir/upload.$testno";

        logmsg "Store test number $testno in $filename\n";

        open(my $file, ">", $filename) ||
            return 0; # failed to open output

        my $line;
        my $ulsize = 0;
        my $disc = 0;
        my $raw;
        while(5 == (sysread \*SFREAD, $line, 5)) {
            if($line eq "DATA\n") {
                my $i;
                my $eob;
                sysread \*SFREAD, $i, 5;

                my $size = 0;
                if($i =~ /^([0-9a-fA-F]{4})\n/) {
                    $size = hex($1);
                }

                read_mainsockf(\$line, $size);

                $ulsize += $size;
                print $file $line if(!$nosave);

                $raw .= $line;
                if($raw =~ /(?:^|\x0d\x0a)\x2e\x0d\x0a/) {
                    # end of data marker!
                    $eob = 1;
                }

                logmsg "> Appending $size bytes to file\n";

                if($eob) {
                    logmsg "Found SMTP EOB marker\n";
                    last;
                }
            }
            elsif($line eq "DISC\n") {
                # disconnect!
                $disc = 1;
                printf SFWRITE "ACKD\n";
                last;
            }
            else {
                logmsg "No support for: $line";
                last;
            }
        }

        if($nosave) {
            print $file "$ulsize bytes would have been stored here\n";
        }

        close($file);

        logmsg "received $ulsize bytes upload\n";

        sendcontrol "250 OK, data received!\r\n";
    }

    return 0;
}

sub NOOP_smtp {
    my ($args) = @_;

    if($args) {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    else {
        sendcontrol "250 OK\r\n";
    }

    return 0;
}

sub RSET_smtp {
    my ($args) = @_;

    if($args) {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    else {
        sendcontrol "250 Resetting\r\n";
    }

    return 0;
}

sub HELP_smtp {
    my ($args) = @_;

    # One argument is optional
    if($args) {
        logmsg "HELP_smtp got $args\n";
    }

    if($smtp_client eq "verifiedserver") {
        # This is the secret command that verifies that this actually is
        # the curl test server
        sendcontrol "214 WE ROOLZ: $$\r\n";

        if($verbose) {
            print STDERR "FTPD: We returned proof we are the test server\n";
        }

        logmsg "return proof we are we\n";
    }
    else {
        sendcontrol "214-This server supports the following commands:\r\n";

        if(@auth_mechs) {
            sendcontrol "214 HELO EHLO RCPT DATA RSET MAIL VRFY EXPN QUIT HELP AUTH\r\n";
        }
        else {
            sendcontrol "214 HELO EHLO RCPT DATA RSET MAIL VRFY EXPN QUIT HELP\r\n";
        }
    }

    return 0;
}

sub VRFY_smtp {
    my ($args) = @_;
    my ($username, $address) = split(/ /, $args, 2);

    logmsg "VRFY_smtp got $args\n";

    if($username eq "") {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    else {
        my $smtputf8 = grep /^SMTPUTF8$/, @capabilities;

        # Validate the username (only a valid local or external username is
        # allowed, such as user or user@example.com)
        if((!$smtputf8 && $username =~
           /^([a-zA-Z0-9._%+-]+)(\@(([a-zA-Z0-9-]+)\.)+([a-zA-Z]{2,4}))?$/) ||
           ($smtputf8 && $username =~
           /^([a-zA-Z0-9\x{80}-\x{ff}._%+-]+)(\@(([a-zA-Z0-9\x{80}-\x{ff}-]+)\.)+([a-zA-Z]{2,4}))?$/)) {

            my @data = getreplydata($smtp_client);

            if(!@data) {
                if($username !~
                   /^([a-zA-Z0-9._%+-]+)\@(([a-zA-Z0-9-]+)\.)+([a-zA-Z]{2,4})$/) {
                  push @data, "250 <$username\@example.com>\r\n"
                }
                else {
                  push @data, "250 <$username>\r\n"
                }
            }

            for my $d (@data) {
                sendcontrol $d;
            }
        }
        else {
            sendcontrol "501 Invalid address\r\n";
        }
    }

    return 0;
}

sub EXPN_smtp {
    my ($list_name) = @_;

    logmsg "EXPN_smtp got $list_name\n";

    if(!$list_name) {
        sendcontrol "501 Unrecognized parameter\r\n";
    }
    else {
        my @data = getreplydata($smtp_client);

        for my $d (@data) {
            sendcontrol $d;
        }
    }

    return 0;
}

sub QUIT_smtp {
    sendcontrol "221 curl $smtp_type server signing off\r\n";

    return 0;
}

# What was deleted by IMAP STORE / POP3 DELE commands
my @deleted;

################
################ IMAP commands
################

# global to allow the command functions to read it
my $cmdid;

# what was picked by SELECT
my $selected;

# Any IMAP parameter can come in escaped and in double quotes.
# This function is dumb (so far) and removes the quotes if present.
sub fix_imap_params {
    foreach (@_) {
        $_ = $1 if /^"(.*)"$/;
    }
}

sub CAPABILITY_imap {
    if((!@capabilities) && (!@auth_mechs)) {
        sendcontrol "$cmdid BAD Command\r\n";
    }
    else {
        my $data;

        # Calculate the CAPABILITY response
        $data = "* CAPABILITY IMAP4";

        for my $c (@capabilities) {
            $data .= " $c";
        }

        for my $am (@auth_mechs) {
            $data .= " AUTH=$am";
        }

        $data .= " pingpong test server\r\n";

        # Send the CAPABILITY response
        sendcontrol $data;
        sendcontrol "$cmdid OK CAPABILITY completed\r\n";
    }

    return 0;
}

sub LOGIN_imap {
    my ($args) = @_;
    my ($user, $password) = split(/ /, $args, 2);
    fix_imap_params($user, $password);

    logmsg "LOGIN_imap got $args\n";

    if($user eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "$cmdid OK LOGIN completed\r\n";
    }

    return 0;
}

sub SELECT_imap {
    my ($mailbox) = @_;
    fix_imap_params($mailbox);

    logmsg "SELECT_imap got test $mailbox\n";

    if($mailbox eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        # Example from RFC 3501, 6.3.1. SELECT Command
        sendcontrol "* 172 EXISTS\r\n";
        sendcontrol "* 1 RECENT\r\n";
        sendcontrol "* OK [UNSEEN 12] Message 12 is first unseen\r\n";
        sendcontrol "* OK [UIDVALIDITY 3857529045] UIDs valid\r\n";
        sendcontrol "* OK [UIDNEXT 4392] Predicted next UID\r\n";
        sendcontrol "* FLAGS (\\Answered \\Flagged \\Deleted \\Seen \\Draft)\r\n";
        sendcontrol "* OK [PERMANENTFLAGS (\\Deleted \\Seen \\*)] Limited\r\n";
        sendcontrol "$cmdid OK [READ-WRITE] SELECT completed\r\n";

        $selected = $mailbox;
    }

    return 0;
}

sub FETCH_imap {
    my ($args) = @_;
    my ($uid, $how) = split(/ /, $args, 2);
    fix_imap_params($uid, $how);

    logmsg "FETCH_imap got $args\n";

    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    else {
        my @data;
        my $size;

        if($selected eq "verifiedserver") {
            # this is the secret command that verifies that this actually is
            # the curl test server
            my $response = "WE ROOLZ: $$\r\n";
            if($verbose) {
                print STDERR "FTPD: We returned proof we are the test server\n";
            }
            $data[0] = $response;
            logmsg "return proof we are we\n";
        }
        else {
            # send mail content
            logmsg "retrieve a mail\n";

            @data = getreplydata($selected);
        }

        for (@data) {
            $size += length($_);
        }

        sendcontrol "* $uid FETCH ($how {$size}\r\n";

        for my $d (@data) {
            sendcontrol $d;
        }

        # Set the custom extra header content with POSTFETCH
        sendcontrol "$postfetch)\r\n";
        sendcontrol "$cmdid OK FETCH completed\r\n";
    }

    return 0;
}

sub APPEND_imap {
    my ($args) = @_;

    logmsg "APPEND_imap got $args\n";

    $args =~ /^([^ ]+) [^{]*\{(\d+)\}$/;
    my ($mailbox, $size) = ($1, $2);
    fix_imap_params($mailbox);

    if($mailbox eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "+ Ready for literal data\r\n";

        my $testno = $mailbox;
        my $filename = "$logdir/upload.$testno";

        logmsg "Store test number $testno in $filename\n";

        open(my $file, ">", $filename) ||
            return 0; # failed to open output

        my $received = 0;
        my $line;
        while(5 == (sysread \*SFREAD, $line, 5)) {
            if($line eq "DATA\n") {
                sysread \*SFREAD, $line, 5;

                my $chunksize = 0;
                if($line =~ /^([0-9a-fA-F]{4})\n/) {
                    $chunksize = hex($1);
                }

                read_mainsockf(\$line, $chunksize);

                my $left = $size - $received;
                my $datasize = ($left > $chunksize) ? $chunksize : $left;

                if($datasize > 0) {
                    logmsg "> Appending $datasize bytes to file\n";
                    print $file substr($line, 0, $datasize) if(!$nosave);
                    $line = substr($line, $datasize);

                    $received += $datasize;
                    if($received == $size) {
                        logmsg "Received all data, waiting for final CRLF.\n";
                    }
                }

                if($received == $size && $line eq "\r\n") {
                    last;
                }
            }
            elsif($line eq "DISC\n") {
                logmsg "Unexpected disconnect!\n";
                printf SFWRITE "ACKD\n";
                last;
            }
            else {
                logmsg "No support for: $line";
                last;
            }
        }

        if($nosave) {
            print $file "$size bytes would have been stored here\n";
        }

        close($file);

        logmsg "received $size bytes upload\n";

        sendcontrol "$cmdid OK APPEND completed\r\n";
    }

    return 0;
}

sub STORE_imap {
    my ($args) = @_;
    my ($uid, $what, $value) = split(/ /, $args, 3);
    fix_imap_params($uid);

    logmsg "STORE_imap got $args\n";

    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    elsif(($uid eq "") || ($what ne "+Flags") || ($value eq "")) {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        if($value eq "\\Deleted") {
            push(@deleted, $uid);
        }

        sendcontrol "* $uid FETCH (FLAGS (\\Seen $value))\r\n";
        sendcontrol "$cmdid OK STORE completed\r\n";
    }

    return 0;
}

sub LIST_imap {
    my ($args) = @_;
    my ($reference, $mailbox) = split(/ /, $args, 2);
    fix_imap_params($reference, $mailbox);

    logmsg "LIST_imap got $args\n";

    if($reference eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    elsif($reference eq "verifiedserver") {
        # this is the secret command that verifies that this actually is
        # the curl test server
        sendcontrol "* LIST () \"/\" \"WE ROOLZ: $$\"\r\n";
        sendcontrol "$cmdid OK LIST Completed\r\n";

        if($verbose) {
            print STDERR "FTPD: We returned proof we are the test server\n";
        }

        logmsg "return proof we are we\n";
    }
    else {
        my @data = getreplydata($reference);

        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK LIST Completed\r\n";
    }

    return 0;
}

sub LSUB_imap {
    my ($args) = @_;
    my ($reference, $mailbox) = split(/ /, $args, 2);
    fix_imap_params($reference, $mailbox);

    logmsg "LSUB_imap got $args\n";

    if($reference eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        my @data = getreplydata($reference);

        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK LSUB Completed\r\n";
    }

    return 0;
}

sub EXAMINE_imap {
    my ($mailbox) = @_;
    fix_imap_params($mailbox);

    logmsg "EXAMINE_imap got $mailbox\n";

    if($mailbox eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        my @data = getreplydata($mailbox);

        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK [READ-ONLY] EXAMINE completed\r\n";
    }

    return 0;
}

sub STATUS_imap {
    my ($args) = @_;
    my ($mailbox, $what) = split(/ /, $args, 2);
    fix_imap_params($mailbox);

    logmsg "STATUS_imap got $args\n";

    if($mailbox eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        my @data = getreplydata($mailbox);

        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK STATUS completed\r\n";
    }

    return 0;
}

sub SEARCH_imap {
    my ($what) = @_;
    fix_imap_params($what);

    logmsg "SEARCH_imap got $what\n";

    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    elsif($what eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        my @data = getreplydata($selected);

        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK SEARCH completed\r\n";
    }

    return 0;
}

sub CREATE_imap {
    my ($args) = @_;
    fix_imap_params($args);

    logmsg "CREATE_imap got $args\n";

    if($args eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "$cmdid OK CREATE completed\r\n";
    }

    return 0;
}

sub DELETE_imap {
    my ($args) = @_;
    fix_imap_params($args);

    logmsg "DELETE_imap got $args\n";

    if($args eq "") {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "$cmdid OK DELETE completed\r\n";
    }

    return 0;
}

sub RENAME_imap {
    my ($args) = @_;
    my ($from_mailbox, $to_mailbox) = split(/ /, $args, 2);
    fix_imap_params($from_mailbox, $to_mailbox);

    logmsg "RENAME_imap got $args\n";

    if(($from_mailbox eq "") || ($to_mailbox eq "")) {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "$cmdid OK RENAME completed\r\n";
    }

    return 0;
}

sub CHECK_imap {
    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    else {
        sendcontrol "$cmdid OK CHECK completed\r\n";
    }

    return 0;
}

sub CLOSE_imap {
    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    elsif(!@deleted) {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "$cmdid OK CLOSE completed\r\n";

        @deleted = ();
    }

    return 0;
}

sub EXPUNGE_imap {
    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    else {
        if(!@deleted) {
            # Report the number of existing messages as per the SELECT
            # command
            sendcontrol "* 172 EXISTS\r\n";
        }
        else {
            # Report the message UIDs being deleted
            for my $d (@deleted) {
                sendcontrol "* $d EXPUNGE\r\n";
            }

            @deleted = ();
        }

        sendcontrol "$cmdid OK EXPUNGE completed\r\n";
    }

    return 0;
}

sub COPY_imap {
    my ($args) = @_;
    my ($uid, $mailbox) = split(/ /, $args, 2);
    fix_imap_params($uid, $mailbox);

    logmsg "COPY_imap got $args\n";

    if(($uid eq "") || ($mailbox eq "")) {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        sendcontrol "$cmdid OK COPY completed\r\n";
    }

    return 0;
}

sub IDLE_imap {
    logmsg "IDLE received\n";

    sendcontrol "+ entering idle mode\r\n";
    return 0;
}

sub UID_imap {
    my ($args) = @_;
    my ($command) = split(/ /, $args, 1);
    fix_imap_params($command);

    logmsg "UID_imap got $args\n";

    if($selected eq "") {
        sendcontrol "$cmdid BAD Command received in Invalid state\r\n";
    }
    elsif(substr($command, 0, 5) eq "FETCH"){
        my $func = $commandfunc{"FETCH"};
        if($func) {
            &$func($args, $command);
        }
    }
    elsif(($command ne "COPY") &&
          ($command ne "STORE") && ($command ne "SEARCH")) {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        my @data = getreplydata($selected);

        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK $command completed\r\n";
    }

    return 0;
}

sub NOOP_imap {
    my ($args) = @_;
    my @data = (
        "* 22 EXPUNGE\r\n",
        "* 23 EXISTS\r\n",
        "* 3 RECENT\r\n",
        "* 14 FETCH (FLAGS (\\Seen \\Deleted))\r\n",
    );

    if($args) {
        sendcontrol "$cmdid BAD Command Argument\r\n";
    }
    else {
        for my $d (@data) {
            sendcontrol $d;
        }

        sendcontrol "$cmdid OK NOOP completed\r\n";
    }

    return 0;
}

sub LOGOUT_imap {
    sendcontrol "* BYE curl IMAP server signing off\r\n";
    sendcontrol "$cmdid OK LOGOUT completed\r\n";

    return 0;
}

################
################ POP3 commands
################

# Who is attempting to log in
my $username;

sub CAPA_pop3 {
    my @list = ();
    my $mechs;

    # Calculate the capability list based on the specified capabilities
    # (except APOP) and any authentication mechanisms
    for my $c (@capabilities) {
        push @list, "$c\r\n" unless $c eq "APOP";
    }

    for my $am (@auth_mechs) {
        if(!$mechs) {
            $mechs = $am;
        }
        else {
            $mechs .= " $am";
        }
    }

    if($mechs) {
        push @list, "SASL $mechs\r\n";
    }

    if(!@list) {
        sendcontrol "-ERR Unrecognized command\r\n";
    }
    else {
        my @data = ();

        # Calculate the CAPA response
        push @data, "+OK List of capabilities follows\r\n";

        for my $l (@list) {
            push @data, "$l\r\n";
        }

        push @data, "IMPLEMENTATION POP3 pingpong test server\r\n";

        # Send the CAPA response
        for my $d (@data) {
            sendcontrol $d;
        }

        # End with the magic 3-byte end of listing marker
        sendcontrol ".\r\n";
    }

    return 0;
}

sub APOP_pop3 {
    my ($args) = @_;
    my ($user, $secret) = split(/ /, $args, 2);

    if(!grep /^APOP$/, @capabilities) {
        sendcontrol "-ERR Unrecognized command\r\n";
    }
    elsif(($user eq "") || ($secret eq "")) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        my $digest = Digest::MD5::md5_hex($POP3_TIMESTAMP, $TEXT_PASSWORD);

        if($secret ne $digest) {
            sendcontrol "-ERR Login failure\r\n";
        }
        else {
            sendcontrol "+OK Login successful\r\n";
        }
    }

    return 0;
}

sub AUTH_pop3 {
    if(!@auth_mechs) {
        sendcontrol "-ERR Unrecognized command\r\n";
    }
    else {
        my @data = ();

        # Calculate the AUTH response
        push @data, "+OK List of supported mechanisms follows\r\n";

        for my $am (@auth_mechs) {
            push @data, "$am\r\n";
        }

        # Send the AUTH response
        for my $d (@data) {
            sendcontrol $d;
        }

        # End with the magic 3-byte end of listing marker
        sendcontrol ".\r\n";
    }

    return 0;
}

sub USER_pop3 {
    my ($user) = @_;

    logmsg "USER_pop3 got $user\n";

    if(!$user) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        $username = $user;

        sendcontrol "+OK\r\n";
    }

    return 0;
}

sub PASS_pop3 {
    my ($password) = @_;

    logmsg "PASS_pop3 got $password\n";

    sendcontrol "+OK Login successful\r\n";

    return 0;
}

sub RETR_pop3 {
    my ($msgid) = @_;
    my @data;

    if($msgid =~ /^verifiedserver$/) {
        # this is the secret command that verifies that this actually is
        # the curl test server
        my $response = "WE ROOLZ: $$\r\n";
        if($verbose) {
            print STDERR "FTPD: We returned proof we are the test server\n";
        }
        $data[0] = $response;
        logmsg "return proof we are we\n";
    }
    else {
        # send mail content
        logmsg "retrieve a mail\n";

        @data = getreplydata($msgid);
    }

    sendcontrol "+OK Mail transfer starts\r\n";

    for my $d (@data) {
        sendcontrol $d;
    }

    # end with the magic 3-byte end of mail marker, assumes that the
    # mail body ends with a CRLF!
    sendcontrol ".\r\n";

    return 0;
}

sub LIST_pop3 {
    my @data = getpart("reply", "data");

    logmsg "retrieve a message list\n";

    sendcontrol "+OK Listing starts\r\n";

    for my $d (@data) {
        sendcontrol $d;
    }

    # End with the magic 3-byte end of listing marker
    sendcontrol ".\r\n";

    return 0;
}

sub DELE_pop3 {
    my ($msgid) = @_;

    logmsg "DELE_pop3 got $msgid\n";

    if(!$msgid) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        push (@deleted, $msgid);

        sendcontrol "+OK\r\n";
    }

    return 0;
}

sub STAT_pop3 {
    my ($args) = @_;

    if($args) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        # Send statistics for the built-in fake message list as
        # detailed in the LIST_pop3 function above
        sendcontrol "+OK 3 4294967800\r\n";
    }

    return 0;
}

sub NOOP_pop3 {
    my ($args) = @_;

    if($args) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        sendcontrol "+OK\r\n";
    }

    return 0;
}

sub UIDL_pop3 {
    # This is a built-in fake-message UID list
    my @data = (
        "1 1\r\n",
        "2 2\r\n",
        "3 4\r\n", # Note that UID 3 is a simulated "deleted" message
    );

    if(!grep /^UIDL$/, @capabilities) {
        sendcontrol "-ERR Unrecognized command\r\n";
    }
    else {
        logmsg "retrieve a message UID list\n";

        sendcontrol "+OK Listing starts\r\n";

        for my $d (@data) {
            sendcontrol $d;
        }

        # End with the magic 3-byte end of listing marker
        sendcontrol ".\r\n";
    }

    return 0;
}

sub TOP_pop3 {
    my ($args) = @_;
    my ($msgid, $lines) = split(/ /, $args, 2);

    logmsg "TOP_pop3 got $args\n";

    if(!grep /^TOP$/, @capabilities) {
        sendcontrol "-ERR Unrecognized command\r\n";
    }
    elsif(($msgid eq "") || ($lines eq "")) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        if($lines == "0") {
            logmsg "retrieve header of mail\n";
        }
        else {
            logmsg "retrieve top $lines lines of mail\n";
        }

        my @data = getreplydata($msgid);

        sendcontrol "+OK Mail transfer starts\r\n";

        # Send mail content
        for my $d (@data) {
            sendcontrol $d;
        }

        # End with the magic 3-byte end of mail marker, assumes that the
        # mail body ends with a CRLF!
        sendcontrol ".\r\n";
    }

    return 0;
}

sub RSET_pop3 {
    my ($args) = @_;

    if($args) {
        sendcontrol "-ERR Protocol error\r\n";
    }
    else {
        if(@deleted) {
            logmsg "resetting @deleted message(s)\n";

            @deleted = ();
        }

        sendcontrol "+OK\r\n";
    }

    return 0;
}

sub QUIT_pop3 {
    if(@deleted) {
        logmsg "deleting @deleted message(s)\n";

        @deleted = ();
    }

    sendcontrol "+OK curl POP3 server signing off\r\n";

    return 0;
}

################
################ FTP commands
################
my $rest = 0;
sub REST_ftp {
    $rest = $_[0];
    logmsg "Set REST position to $rest\n"
}

sub switch_directory_goto {
    my $target_dir = $_;

    if(!$ftptargetdir) {
        $ftptargetdir = "/";
    }

    if($target_dir eq "") {
        $ftptargetdir = "/";
    }
    elsif($target_dir eq "..") {
        if($ftptargetdir eq "/") {
            $ftptargetdir = "/";
        }
        else {
            $ftptargetdir =~ s/[[:alnum:]]+\/$//;
        }
    }
    else {
        $ftptargetdir .= $target_dir . "/";
    }
}

sub switch_directory {
    my $target_dir = $_[0];

    if($target_dir =~ /^test-(\d+)/) {
        $cwd_testno = $1;
    }
    elsif($target_dir eq "/") {
        $ftptargetdir = "/";
    }
    else {
        my @dirs = split("/", $target_dir);
        for(@dirs) {
          switch_directory_goto($_);
        }
    }
}

sub CWD_ftp {
  my ($folder, $fullcommand) = $_[0];
  switch_directory($folder);
  if($ftptargetdir =~ /^\/fully_simulated/) {
      $ftplistparserstate = "enabled";
      logmsg "enabled FTP list parser mode\n";
  }
  else {
    undef $ftplistparserstate;
  }
}

sub PWD_ftp {
    my $mydir;
    $mydir = $ftptargetdir ? $ftptargetdir : "/";

    if($mydir ne "/") {
        $mydir =~ s/\/$//;
    }
    sendcontrol "257 \"$mydir\" is current directory\r\n";
}

sub LIST_ftp {
    #  print "150 ASCII data connection for /bin/ls (193.15.23.1,59196) (0 bytes)\r\n";

    if($datasockf_conn eq 'no') {
        if($nodataconn425) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "425 Can't open data connection\r\n";
        }
        elsif($nodataconn421) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "421 Connection timed out\r\n";
        }
        elsif($nodataconn150) {
            sendcontrol "150 Opening data connection\r\n";
            # client shall timeout
        }
        else {
            # client shall timeout
        }
        return 0;
    }

    logmsg "pass LIST data on data connection\n";

    if($ftplistparserstate) {
        # provide a synthetic response
        my @ftpdir = ftp_contentlist($ftptargetdir);
        # old hard-coded style
        for(@ftpdir) {
            senddata $_;
        }
    }
    else {
        my @data = getpart("reply", "data");
        for(@data) {
            my $send = $_;
            # convert all \n to \r\n for ASCII transfer
            $send =~ s/\r\n/\n/g;
            $send =~ s/\n/\r\n/g;
            logmsg "send $send as data\n";
            senddata $send;
        }
    }
    close_dataconn(0);
    sendcontrol "226 ASCII transfer complete\r\n";
    return 0;
}

sub NLST_ftp {
    my @ftpdir = ("file", "with space", "fake", "..", " ..", "funny", "README");

    if($datasockf_conn eq 'no') {
        if($nodataconn425) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "425 Can't open data connection\r\n";
        }
        elsif($nodataconn421) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "421 Connection timed out\r\n";
        }
        elsif($nodataconn150) {
            sendcontrol "150 Opening data connection\r\n";
            # client shall timeout
        }
        else {
            # client shall timeout
        }
        return 0;
    }

    logmsg "pass NLST data on data connection\n";
    for(@ftpdir) {
        senddata "$_\r\n";
    }
    close_dataconn(0);
    sendcontrol "226 ASCII transfer complete\r\n";
    return 0;
}

sub MDTM_ftp {
    my $testno = $_[0];
    my $testpart = "";
    if($testno > 10000) {
        $testpart = $testno % 10000;
        $testno = int($testno / 10000);
    }

    loadtest("$logdir/test$testno");

    my @data = getpart("reply", "mdtm");

    my $reply = $data[0];
    chomp $reply if($reply);

    if($reply && ($reply =~ /^[+-]?\d+$/) && ($reply < 0)) {
        sendcontrol "550 $testno: no such file.\r\n";
    }
    elsif($reply) {
        sendcontrol "$reply\r\n";
    }
    else {
        sendcontrol "500 MDTM: no such command.\r\n";
    }
    return 0;
}

sub SIZE_ftp {
    my $testno = $_[0];

    if($ftplistparserstate) {
        my $size = wildcard_filesize($ftptargetdir, $testno);
        if($size == -1) {
            sendcontrol "550 $testno: No such file or directory.\r\n";
        }
        else {
            sendcontrol "213 $size\r\n";
        }
        return 0;
    }

    if($testno =~ /^verifiedserver$/) {
        my $response = "WE ROOLZ: $$\r\n";
        my $size = length($response);
        sendcontrol "213 $size\r\n";
        return 0;
    }

    if($testno =~ /(\d+)\/?$/) {
        $testno = $1;
    }
    else {
        print STDERR "SIZE_ftp: invalid test number: $testno\n";
        return 1;
    }

    my $testpart = "";
    if($testno > 10000) {
        $testpart = $testno % 10000;
        $testno = int($testno / 10000);
    }

    loadtest("$logdir/test$testno");
    my @data = getpart("reply", "size");

    my $size = $data[0];

    if($size) {
        $size += 0; # make it a number
        if($size > -1) {
            sendcontrol "213 $size\r\n";
        }
        else {
            sendcontrol "550 $testno: No such file or directory.\r\n";
        }
    }
    else {
        $size = 0;
        @data = getpart("reply", "data$testpart");
        for(@data) {
            $size += length($_);
        }
        if($size) {
            sendcontrol "213 $size\r\n";
        }
        else {
            sendcontrol "550 $testno: No such file or directory.\r\n";
        }
    }
    return 0;
}

sub RETR_ftp {
    my ($testno) = @_;

    if($datasockf_conn eq 'no') {
        if($nodataconn425) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "425 Can't open data connection\r\n";
        }
        elsif($nodataconn421) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "421 Connection timed out\r\n";
        }
        elsif($nodataconn150) {
            sendcontrol "150 Opening data connection\r\n";
            # client shall timeout
        }
        else {
            # client shall timeout
        }
        return 0;
    }

    if($ftplistparserstate) {
        my @content = wildcard_getfile($ftptargetdir, $testno);
        if($content[0] == -1) {
            #file not found
        }
        else {
            my $size = length $content[1];
            sendcontrol "150 Binary data connection for $testno ($size bytes).\r\n",
            senddata $content[1];
            close_dataconn(0);
            sendcontrol "226 File transfer complete\r\n";
        }
        return 0;
    }

    if($testno =~ /^verifiedserver$/) {
        # this is the secret command that verifies that this actually is
        # the curl test server
        my $response = "WE ROOLZ: $$\r\n";
        my $len = length($response);
        sendcontrol "150 Binary junk ($len bytes).\r\n";
        senddata "WE ROOLZ: $$\r\n";
        close_dataconn(0);
        sendcontrol "226 File transfer complete\r\n";
        if($verbose) {
            print STDERR "FTPD: We returned proof we are the test server\n";
        }
        return 0;
    }

    $testno =~ s/^([^0-9]*)//;
    my $testpart = "";
    if($testno > 10000) {
        $testpart = $testno % 10000;
        $testno = int($testno / 10000);
    }

    loadtest("$logdir/test$testno");

    my @data = getpart("reply", "data$testpart");

    my $size = 0;
    for(@data) {
        $size += length($_);
    }

    my %hash = getpartattr("reply", "data$testpart");

    if($size || $hash{'sendzero'}) {

        if($rest) {
            # move read pointer forward
            $size -= $rest;
            logmsg "REST $rest was removed from size, makes $size left\n";
            $rest = 0; # reset REST offset again
        }
        if($retrweirdo) {
            sendcontrol "150 Binary data connection for $testno () ($size bytes).\r\n",
            "226 File transfer complete\r\n";

            for(@data) {
                my $send = $_;
                senddata $send;
            }
            close_dataconn(0);
            $retrweirdo = 0; # switch off the weirdo again!
        }
        else {
            my $sz = "($size bytes)";
            if($retrnosize) {
                $sz = "size?";
            }
            elsif($retrsize > 0) {
                $sz = "($retrsize bytes)";
            }

            sendcontrol "150 Binary data connection for $testno ($testpart) $sz.\r\n";

            for(@data) {
                my $send = $_;
                senddata $send;
            }
            close_dataconn(0);
            sendcontrol "226 File transfer complete\r\n";
        }
    }
    else {
        sendcontrol "550 $testno: No such file or directory.\r\n";
    }
    return 0;
}

sub STOR_ftp {
    my $testno = $_[0];

    my $filename = "$logdir/upload.$testno";

    if($datasockf_conn eq 'no') {
        if($nodataconn425) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "425 Can't open data connection\r\n";
        }
        elsif($nodataconn421) {
            sendcontrol "150 Opening data connection\r\n";
            sendcontrol "421 Connection timed out\r\n";
        }
        elsif($nodataconn150) {
            sendcontrol "150 Opening data connection\r\n";
            # client shall timeout
        }
        else {
            # client shall timeout
        }
        return 0;
    }

    logmsg "STOR test number $testno in $filename\n";

    sendcontrol "125 Gimme gimme gimme!\r\n";

    open(my $file, ">", $filename) ||
        return 0; # failed to open output

    my $line;
    my $ulsize = 0;
    my $disc = 0;
    while(5 == (sysread DREAD, $line, 5)) {
        if($line eq "DATA\n") {
            my $i;
            sysread DREAD, $i, 5;

            my $size = 0;
            if($i =~ /^([0-9a-fA-F]{4})\n/) {
                $size = hex($1);
            }

            read_datasockf(\$line, $size);

            #print STDERR "  GOT: $size bytes\n";

            $ulsize += $size;
            print $file $line if(!$nosave);
            logmsg "> Appending $size bytes to file\n";
        }
        elsif($line eq "DISC\n") {
            # disconnect!
            $disc = 1;
            printf DWRITE "ACKD\n";
            last;
        }
        else {
            logmsg "No support for: $line";
            last;
        }
        if($storeresp) {
            # abort early
            last;
        }
    }
    if($nosave) {
        print $file "$ulsize bytes would have been stored here\n";
    }
    close($file);
    close_dataconn($disc);
    logmsg "received $ulsize bytes upload\n";
    if($storeresp) {
        sendcontrol "$storeresp\r\n";
    }
    else {
        sendcontrol "226 File transfer complete\r\n";
    }
    return 0;
}

sub PASV_ftp {
    my ($arg, $cmd) = @_;
    my $pasvport;

    # kill previous data connection sockfilt when alive
    if($datasockf_runs eq 'yes') {
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt for $datasockf_mode data channel killed\n";
    }
    datasockf_state('STOPPED');

    logmsg "====> Passive DATA channel requested by client\n";

    logmsg "DATA sockfilt for passive data channel starting...\n";

    # We fire up a new sockfilt to do the data transfer for us.
    my @datasockfcmd = (server_exe_args('sockfilt'),
        "--ipv$ipvnum", "--port", 0,
        "--pidfile", $datasockf_pidfile,
        "--logfile", $datasockf_logfile);
    if($nodataconn) {
        push(@datasockfcmd, '--bindonly');
    }
    $slavepid = open2(\*DREAD, \*DWRITE, @datasockfcmd);

    if($nodataconn) {
        datasockf_state('PASSIVE_NODATACONN');
    }
    else {
        datasockf_state('PASSIVE');
    }

    print STDERR "@datasockfcmd\n" if($verbose);

    print DWRITE "PING\n";
    my $pong;
    sysread_or_die(\*DREAD, \$pong, 5);

    if($pong =~ /^FAIL/) {
        logmsg "DATA sockfilt said: FAIL\n";
        logmsg "DATA sockfilt for passive data channel failed\n";
        logmsg "DATA sockfilt not running\n";
        datasockf_state('STOPPED');
        sendcontrol "500 no free ports!\r\n";
        return;
    }
    elsif($pong !~ /^PONG/) {
        logmsg "DATA sockfilt unexpected response: $pong\n";
        logmsg "DATA sockfilt for passive data channel failed\n";
        logmsg "DATA sockfilt killed now\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt not running\n";
        datasockf_state('STOPPED');
        sendcontrol "500 no free ports!\r\n";
        return;
    }

    logmsg "DATA sockfilt for passive data channel started (pid $slavepid)\n";

    # Find out on what port we listen on or have bound
    my $i;
    print DWRITE "PORT\n";

    # READ the response code
    sysread_or_die(\*DREAD, \$i, 5);

    # READ the response size
    sysread_or_die(\*DREAD, \$i, 5);

    my $size = 0;
    if($i =~ /^([0-9a-fA-F]{4})\n/) {
        $size = hex($1);
    }

    # READ the response data
    read_datasockf(\$i, $size);

    # The data is in the format
    # IPvX/NNN

    if($i =~ /IPv(\d)\/(\d+)/) {
        # FIX: deal with IP protocol version
        $pasvport = $2;
    }

    if(!$pasvport) {
        logmsg "DATA sockfilt unknown listener port\n";
        logmsg "DATA sockfilt for passive data channel failed\n";
        logmsg "DATA sockfilt killed now\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt not running\n";
        datasockf_state('STOPPED');
        sendcontrol "500 no free ports!\r\n";
        return;
    }

    if($nodataconn) {
        my $str = nodataconn_str();
        logmsg "DATA sockfilt for passive data channel ($str) bound on port ".
               "$pasvport\n";
    }
    else {
        logmsg "DATA sockfilt for passive data channel listens on port ".
               "$pasvport\n";
    }

    if($cmd ne "EPSV") {
        # PASV reply
        my $p = $listenaddr;
        $p =~ s/\./,/g;
        if($pasvbadip) {
            $p = "1,2,3,4";
        }
        sendcontrol sprintf("227 Entering Passive Mode ($p,%d,%d)\r\n",
                            int($pasvport / 256), int($pasvport % 256));
    }
    else {
        # EPSV reply
        sendcontrol sprintf("229 Entering Passive Mode (|||%d|)\r\n", $pasvport);
    }

    logmsg "Client has been notified that DATA conn ".
           "will be accepted on port $pasvport\n";

    if($nodataconn) {
        my $str = nodataconn_str();
        logmsg "====> Client fooled ($str)\n";
        return;
    }

    eval {
        local $SIG{ALRM} = sub { die "alarm\n" };

        # assume swift operations unless explicitly slow
        alarm ($datadelay ? 20 : 2);

        # Wait for 'CNCT'
        my $input;

        # FIX: Monitor ctrl conn for disconnect

        while(sysread(DREAD, $input, 5)) {

            if($input !~ /^CNCT/) {
                # we wait for a connected client
                logmsg "Odd, we got $input from client\n";
                next;
            }
            logmsg "Client connects to port $pasvport\n";
            last;
        }
        alarm 0;
    };
    if($@) {
        # timed out
        logmsg "$srvrname server timed out awaiting data connection ".
            "on port $pasvport\n";
        logmsg "accept failed or connection not even attempted\n";
        logmsg "DATA sockfilt killed now\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt not running\n";
        datasockf_state('STOPPED');
        return;
    }
    else {
        logmsg "====> Client established passive DATA connection ".
               "on port $pasvport\n";
    }

    return;
}

#
# Support both PORT and EPRT here.
#

sub PORT_ftp {
    my ($arg, $cmd) = @_;
    my $port;
    my $addr;

    # kill previous data connection sockfilt when alive
    if($datasockf_runs eq 'yes') {
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt for $datasockf_mode data channel killed\n";
    }
    datasockf_state('STOPPED');

    logmsg "====> Active DATA channel requested by client\n";

    # We always ignore the given IP and use localhost.

    if($cmd eq "PORT") {
        if($arg !~ /(\d+),(\d+),(\d+),(\d+),(\d+),(\d+)/) {
            logmsg "DATA sockfilt for active data channel not started ".
                   "(bad PORT-line: $arg)\n";
            sendcontrol "500 silly you, go away\r\n";
            return;
        }
        $port = ($5 << 8) + $6;
        $addr = "$1.$2.$3.$4";
    }
    # EPRT |2|::1|49706|
    elsif($cmd eq "EPRT") {
        if($arg !~ /(\d+)\|([^\|]+)\|(\d+)/) {
            logmsg "DATA sockfilt for active data channel not started ".
                   "(bad EPRT-line: $arg)\n";
            sendcontrol "500 silly you, go away\r\n";
            return;
        }
        sendcontrol "200 Thanks for dropping by. We contact you later\r\n";
        $port = $3;
        $addr = $2;
    }
    else {
        logmsg "DATA sockfilt for active data channel not started ".
               "(invalid command: $cmd)\n";
        sendcontrol "500 we don't like $cmd now\r\n";
        return;
    }

    if(!$port || $port > 65535) {
        logmsg "DATA sockfilt for active data channel not started ".
               "(illegal PORT number: $port)\n";
        return;
    }

    if($nodataconn) {
        my $str = nodataconn_str();
        logmsg "DATA sockfilt for active data channel not started ($str)\n";
        datasockf_state('ACTIVE_NODATACONN');
        logmsg "====> Active DATA channel not established\n";
        return;
    }

    logmsg "DATA sockfilt for active data channel starting...\n";

    # We fire up a new sockfilt to do the data transfer for us.
    my @datasockfcmd = (server_exe_args('sockfilt'),
        "--ipv$ipvnum", "--connect", $port, "--addr", $addr,
        "--pidfile", $datasockf_pidfile,
        "--logfile", $datasockf_logfile);
    $slavepid = open2(\*DREAD, \*DWRITE, @datasockfcmd);

    datasockf_state('ACTIVE');

    print STDERR "@datasockfcmd\n" if($verbose);

    print DWRITE "PING\n";
    my $pong;
    sysread_or_die(\*DREAD, \$pong, 5);

    if($pong =~ /^FAIL/) {
        logmsg "DATA sockfilt said: FAIL\n";
        logmsg "DATA sockfilt for active data channel failed\n";
        logmsg "DATA sockfilt not running\n";
        datasockf_state('STOPPED');
        # client shall timeout awaiting connection from server
        return;
    }
    elsif($pong !~ /^PONG/) {
        logmsg "DATA sockfilt unexpected response: $pong\n";
        logmsg "DATA sockfilt for active data channel failed\n";
        logmsg "DATA sockfilt killed now\n";
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt not running\n";
        datasockf_state('STOPPED');
        # client shall timeout awaiting connection from server
        return;
    }

    logmsg "DATA sockfilt for active data channel started (pid $slavepid)\n";

    logmsg "====> Active DATA channel connected to client port $port\n";

    return;
}

#**********************************************************************
# datasockf_state is used to change variables that keep state info
# relative to the FTP secondary or data sockfilt process as soon as
# one of the five possible stable states is reached. Variables that
# are modified by this sub may be checked independently but should
# not be changed except by calling this sub.
#
sub datasockf_state {
    my $state = $_[0];

    if($state eq 'STOPPED') {
        # Data sockfilter initial state, not running,
        # not connected and not used.
        $datasockf_state = $state;
        $datasockf_mode = 'none';
        $datasockf_runs = 'no';
        $datasockf_conn = 'no';
    }
    elsif($state eq 'PASSIVE') {
        # Data sockfilter accepted connection from client.
        $datasockf_state = $state;
        $datasockf_mode = 'passive';
        $datasockf_runs = 'yes';
        $datasockf_conn = 'yes';
    }
    elsif($state eq 'ACTIVE') {
        # Data sockfilter has connected to client.
        $datasockf_state = $state;
        $datasockf_mode = 'active';
        $datasockf_runs = 'yes';
        $datasockf_conn = 'yes';
    }
    elsif($state eq 'PASSIVE_NODATACONN') {
        # Data sockfilter bound port without listening,
        # client will not be able to establish data connection.
        $datasockf_state = $state;
        $datasockf_mode = 'passive';
        $datasockf_runs = 'yes';
        $datasockf_conn = 'no';
    }
    elsif($state eq 'ACTIVE_NODATACONN') {
        # Data sockfilter does not even run,
        # client awaits data connection from server in vain.
        $datasockf_state = $state;
        $datasockf_mode = 'active';
        $datasockf_runs = 'no';
        $datasockf_conn = 'no';
    }
    else {
        die "Internal error. Unknown datasockf state: $state!";
    }
}

#**********************************************************************
# nodataconn_str returns string of effective nodataconn command. Notice
# that $nodataconn may be set alone or in addition to a $nodataconnXXX.
#
sub nodataconn_str {
    my $str;
    # order matters
    $str = 'NODATACONN' if($nodataconn);
    $str = 'NODATACONN425' if($nodataconn425);
    $str = 'NODATACONN421' if($nodataconn421);
    $str = 'NODATACONN150' if($nodataconn150);
    return $str;
}

#**********************************************************************
# customize configures test server operation for each curl test, reading
# configuration commands/parameters from server commands file each time
# a new client control connection is established with the test server.
# On success returns 1, otherwise zero.
#
sub customize {
    my($cmdfile) = @_;
    $ctrldelay = 0;     # default is no throttling of the ctrl stream
    $datadelay = 0;     # default is no throttling of the data stream
    $retrweirdo = 0;    # default is no use of RETRWEIRDO
    $retrnosize = 0;    # default is no use of RETRNOSIZE
    $retrsize = 0;      # default is no use of RETRSIZE
    $pasvbadip = 0;     # default is no use of PASVBADIP
    $nosave = 0;        # default is to actually save uploaded data to file
    $nodataconn = 0;    # default is to establish or accept data channel
    $nodataconn425 = 0; # default is to not send 425 without data channel
    $nodataconn421 = 0; # default is to not send 421 without data channel
    $nodataconn150 = 0; # default is to not send 150 without data channel
    $storeresp = "";    # send as ultimate STOR response
    $postfetch = "";    # send as header after a FETCH response
    @capabilities = (); # default is to not support capability commands
    @auth_mechs = ();   # default is to not support authentication commands
    %fulltextreply = ();#
    %commandreply = (); #
    %customcount = ();  #
    %delayreply = ();   #

    open(my $custom, "<", "$logdir/$SERVERCMD") ||
        return 1;

    logmsg "FTPD: Getting commands from $logdir/$SERVERCMD\n";

    while(<$custom>) {
        if($_ =~ /REPLY \"([A-Z]+ [A-Za-z0-9+-\/=\*. ]+)\" (.*)/) {
            $fulltextreply{$1} = eval "qq{$2}";
            logmsg "FTPD: set custom reply for $1\n";
        }
        elsif($_ =~ /REPLY(LF|) ([A-Za-z0-9+\/=\*]*) (.*)/) {
            $commandreply{$2} = eval "qq{$3}";
            if($1 ne "LF") {
                $commandreply{$2} .= "\r\n";
            }
            else {
                $commandreply{$2} .= "\n";
            }
            if($2 eq "") {
                logmsg "FTPD: set custom reply for empty command\n";
            }
            else {
                logmsg "FTPD: set custom reply for $2 command\n";
            }
        }
        elsif($_ =~ /COUNT ([A-Z]+) (.*)/) {
            # we blank the custom reply for this command when having
            # been used this number of times
            $customcount{$1} = $2;
            logmsg "FTPD: blank custom reply for $1 command after $2 uses\n";
        }
        elsif($_ =~ /DELAY ([A-Z]+) (\d*)/) {
            $delayreply{$1} = $2;
            logmsg "FTPD: delay reply for $1 with $2 seconds\n";
        }
        elsif($_ =~ /POSTFETCH (.*)/) {
            logmsg "FTPD: read POSTFETCH header data\n";
            $postfetch = $1;
        }
        elsif($_ =~ /SLOWDOWNDATA/) {
            $ctrldelay = 0;
            $datadelay = 0.005;
            logmsg "FTPD: send response data with 5ms delay per byte\n";
        }
        elsif($_ =~ /SLOWDOWN/) {
            $ctrldelay = 0.005;
            $datadelay = 0.005;
            logmsg "FTPD: send response with 5ms delay between each byte\n";
        }
        elsif($_ =~ /RETRWEIRDO/) {
            logmsg "FTPD: instructed to use RETRWEIRDO\n";
            $retrweirdo = 1;
        }
        elsif($_ =~ /RETRNOSIZE/) {
            logmsg "FTPD: instructed to use RETRNOSIZE\n";
            $retrnosize = 1;
        }
        elsif($_ =~ /RETRSIZE (\d+)/) {
            $retrsize= $1;
            logmsg "FTPD: instructed to use RETRSIZE = $1\n";
        }
        elsif($_ =~ /PASVBADIP/) {
            logmsg "FTPD: instructed to use PASVBADIP\n";
            $pasvbadip = 1;
        }
        elsif($_ =~ /NODATACONN425/) {
            # applies to both active and passive FTP modes
            logmsg "FTPD: instructed to use NODATACONN425\n";
            $nodataconn425 = 1;
            $nodataconn = 1;
        }
        elsif($_ =~ /NODATACONN421/) {
            # applies to both active and passive FTP modes
            logmsg "FTPD: instructed to use NODATACONN421\n";
            $nodataconn421 = 1;
            $nodataconn = 1;
        }
        elsif($_ =~ /NODATACONN150/) {
            # applies to both active and passive FTP modes
            logmsg "FTPD: instructed to use NODATACONN150\n";
            $nodataconn150 = 1;
            $nodataconn = 1;
        }
        elsif($_ =~ /NODATACONN/) {
            # applies to both active and passive FTP modes
            logmsg "FTPD: instructed to use NODATACONN\n";
            $nodataconn = 1;
        }
        elsif($_ =~ /^STOR (.*)/) {
            $storeresp = $1;
            logmsg "FTPD: instructed to use respond to STOR with '$storeresp'\n";
        }
        elsif($_ =~ /CAPA (.*)/) {
            logmsg "FTPD: instructed to support CAPABILITY command\n";
            @capabilities = split(/ (?!(?:[^" ]|[^"] [^"])+")/, $1);
            foreach (@capabilities) {
                $_ = $1 if /^"(.*)"$/;
            }
        }
        elsif($_ =~ /AUTH (.*)/) {
            logmsg "FTPD: instructed to support AUTHENTICATION command\n";
            @auth_mechs = split(/ /, $1);
        }
        elsif($_ =~ /NOSAVE/) {
            # do not actually store the file we upload - to be used when
            # uploading insanely huge amounts
            $nosave = 1;
            logmsg "FTPD: NOSAVE prevents saving of uploaded data\n";
        }
        elsif($_ =~ /^Testnum (\d+)/){
            $testno = $1;
            logmsg "FTPD: run test case number: $testno\n";
        }
    }
    close($custom);
}

#----------------------------------------------------------------------
#----------------------------------------------------------------------
#---------------------------  END OF SUBS  ----------------------------
#----------------------------------------------------------------------
#----------------------------------------------------------------------

#**********************************************************************
# Parse command line options
#
# Options:
#
# --verbose   # verbose
# --srcdir    # source directory
# --id        # server instance number
# --proto     # server protocol
# --pidfile   # server pid file
# --portfile  # server port file
# --logfile   # server log file
# --logdir    # server log directory
# --ipv4      # server IP version 4
# --ipv6      # server IP version 6
# --port      # server listener port
# --addr      # server address for listener port binding
#
while(@ARGV) {
    if($ARGV[0] eq '--verbose') {
        $verbose = 1;
    }
    elsif($ARGV[0] eq '--srcdir') {
        if($ARGV[1]) {
            $srcdir = $ARGV[1];
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--id') {
        if($ARGV[1] && ($ARGV[1] =~ /^(\d+)$/)) {
            $idnum = $1 if($1 > 0);
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--proto') {
        if($ARGV[1] && ($ARGV[1] =~ /^(ftp|imap|pop3|smtp)$/)) {
            $proto = $1;
            shift @ARGV;
        }
        else {
            die "unsupported protocol $ARGV[1]";
        }
    }
    elsif($ARGV[0] eq '--pidfile') {
        if($ARGV[1]) {
            $pidfile = $ARGV[1];
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--portfile') {
        if($ARGV[1]) {
            $portfile = $ARGV[1];
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--logfile') {
        if($ARGV[1]) {
            $logfile = $ARGV[1];
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--logdir') {
        if($ARGV[1]) {
            $logdir = $ARGV[1];
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--ipv4') {
        $ipvnum = 4;
        $listenaddr = '127.0.0.1' if($listenaddr eq '::1');
    }
    elsif($ARGV[0] eq '--ipv6') {
        $ipvnum = 6;
        $listenaddr = '::1' if($listenaddr eq '127.0.0.1');
    }
    elsif($ARGV[0] eq '--port') {
        if($ARGV[1] =~ /^(\d+)$/) {
            $port = $1;
            shift @ARGV;
        }
    }
    elsif($ARGV[0] eq '--addr') {
        if($ARGV[1]) {
            my $tmpstr = $ARGV[1];
            if($tmpstr =~ /^(\d\d?\d?)\.(\d\d?\d?)\.(\d\d?\d?)\.(\d\d?\d?)$/) {
                $listenaddr = "$1.$2.$3.$4" if($ipvnum == 4);
            }
            elsif($ipvnum == 6) {
                $listenaddr = $tmpstr;
                $listenaddr =~ s/^\[(.*)\]$/$1/;
            }
            shift @ARGV;
        }
    }
    else {
        print STDERR "\nWarning: ftpserver.pl unknown parameter: '$ARGV[0]'\n";
    }
    shift @ARGV;
}

#***************************************************************************
# Initialize command line option dependent variables
#

if($pidfile) {
    # Use our pidfile directory to store the other pidfiles
    $piddir = dirname($pidfile);
}
else {
    # Use the current directory to store all the pidfiles
    $piddir = $path;
    $pidfile = server_pidfilename($piddir, $proto, $ipvnum, $idnum);
}
if(!$portfile) {
    $portfile = $piddir . "/" . $PORTFILE;
}
if(!$srcdir) {
    $srcdir = $ENV{'srcdir'} || '.';
}
if(!$logfile) {
    $logfile = server_logfilename($logdir, $proto, $ipvnum, $idnum);
}

$mainsockf_pidfile = mainsockf_pidfilename($piddir, $proto, $ipvnum, $idnum);
$mainsockf_logfile =
    mainsockf_logfilename($logdir, $proto, $ipvnum, $idnum);

if($proto eq 'ftp') {
    $datasockf_pidfile = datasockf_pidfilename($piddir, $proto, $ipvnum, $idnum);
    $datasockf_logfile =
        datasockf_logfilename($logdir, $proto, $ipvnum, $idnum);
}

$srvrname = servername_str($proto, $ipvnum, $idnum);
$serverlogs_lockfile = "$logdir/$LOCKDIR/${srvrname}.lock";

$idstr = $idnum if($idnum > 1);

protocolsetup($proto);

$SIG{INT} = \&exit_signal_handler;
$SIG{TERM} = \&exit_signal_handler;

startsf();

# actual port
if($portfile && !$port) {
    my $aport;
    open(my $p, "<", $portfile);
    $aport = <$p>;
    close($p);
    $port = 0 + $aport;
}

logmsg sprintf("%s server listens on port IPv${ipvnum}/${port}\n", uc($proto));

open(my $pid, ">", $pidfile);
print $pid $$."\n";
close($pid);

logmsg("logged pid $$ in $pidfile\n");

while(1) {

    # kill previous data connection sockfilt when alive
    if($datasockf_runs eq 'yes') {
        killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose, 'data');
        logmsg "DATA sockfilt for $datasockf_mode data channel killed now\n";
    }
    datasockf_state('STOPPED');

    #
    # We read 'sockfilt' commands.
    #
    my $input;

    logmsg "Awaiting input\n";
    sysread_or_die(\*SFREAD, \$input, 5);

    if($input !~ /^CNCT/) {
        # we wait for a connected client
        logmsg "MAIN sockfilt said: $input";
        next;
    }
    logmsg "====> Client connect\n";

    set_advisor_read_lock($serverlogs_lockfile);
    $serverlogslocked = 1;

    # flush data:
    $| = 1;

    &customize(); # read test control instructions
    loadtest("$logdir/test$testno");

    my $welcome = $commandreply{"welcome"};
    if(!$welcome) {
        $welcome = $displaytext{"welcome"};
    }
    else {
        # clear it after use
        $commandreply{"welcome"} = "";
        if($welcome !~ /\r\n\z/) {
            $welcome .= "\r\n";
        }
    }
    sendcontrol $welcome;

    #remove global variables from last connection
    if($ftplistparserstate) {
      undef $ftplistparserstate;
    }
    if($ftptargetdir) {
      $ftptargetdir = "";
    }

    if($verbose) {
        print STDERR "OUT: $welcome";
    }

    my $full = "";

    while(1) {
        my $i;

        # Now we expect to read DATA\n[hex size]\n[prot], where the [prot]
        # part only is FTP lingo.

        # COMMAND
        sysread_or_die(\*SFREAD, \$i, 5);

        if($i !~ /^DATA/) {
            logmsg "MAIN sockfilt said $i";
            if($i =~ /^DISC/) {
                # disconnect
                printf SFWRITE "ACKD\n";
                last;
            }
            next;
        }

        # SIZE of data
        sysread_or_die(\*SFREAD, \$i, 5);

        my $size = 0;
        if($i =~ /^([0-9a-fA-F]{4})\n/) {
            $size = hex($1);
        }

        # data
        read_mainsockf(\$input, $size);

        ftpmsg $input;

        $full .= $input;

        # Loop until command completion
        next unless($full =~ /\r\n$/);

        # Remove trailing CRLF.
        $full =~ s/[\n\r]+$//;

        my $FTPCMD;
        my $FTPARG;
        if($proto eq "imap") {
            # IMAP is different with its identifier first on the command line
            if(($full =~ /^([^ ]+) ([^ ]+) (.*)/) ||
               ($full =~ /^([^ ]+) ([^ ]+)/)) {
                $cmdid = $1; # set the global variable
                $FTPCMD = $2;
                $FTPARG = $3;
            }
            # IMAP authentication cancellation
            elsif($full =~ /^\*$/) {
                # Command id has already been set
                $FTPCMD = "*";
                $FTPARG = "";
            }
            # IMAP long "commands" are base64 authentication data
            elsif($full =~ /^[A-Z0-9+\/]*={0,2}$/i) {
                # Command id has already been set
                $FTPCMD = $full;
                $FTPARG = "";
            }
            else {
                sendcontrol "$full BAD Command\r\n";
                last;
            }
        }
        elsif($full =~ /^([A-Z]{3,4})(\s(.*))?$/i) {
            $FTPCMD = $1;
            $FTPARG = $3;
        }
        elsif($proto eq "pop3") {
            # POP3 authentication cancellation
            if($full =~ /^\*$/) {
                $FTPCMD = "*";
                $FTPARG = "";
            }
            # POP3 long "commands" are base64 authentication data
            elsif($full =~ /^[A-Z0-9+\/]*={0,2}$/i) {
                $FTPCMD = $full;
                $FTPARG = "";
            }
            else {
                sendcontrol "-ERR Unrecognized command\r\n";
                last;
            }
        }
        elsif($proto eq "smtp") {
            # SMTP authentication cancellation
            if($full =~ /^\*$/) {
                $FTPCMD = "*";
                $FTPARG = "";
            }
            # SMTP long "commands" are base64 authentication data
            elsif($full =~ /^[A-Z0-9+\/]{0,512}={0,2}$/i) {
                $FTPCMD = $full;
                $FTPARG = "";
            }
            else {
                sendcontrol "500 Unrecognized command\r\n";
                last;
            }
        }
        else {
            sendcontrol "500 Unrecognized command\r\n";
            last;
        }

        logmsg "< \"$full\"\n";

        if($verbose) {
            print STDERR "IN: $full\n";
        }

        $full = "";

        my $delay = $delayreply{$FTPCMD};
        if($delay) {
            # go sleep this many seconds!
            logmsg("Sleep for $delay seconds\n");
            my $twentieths = $delay * 20;
            while($twentieths--) {
                Time::HiRes::sleep(0.05) unless($got_exit_signal);
            }
        }

        my $check = 1; # no response yet

        # See if there is a custom reply for the full text
        my $fulltext = $FTPARG ? $FTPCMD . " " . $FTPARG : $FTPCMD;
        my $text = $fulltextreply{$fulltext};
        if($text && ($text ne "")) {
            sendcontrol "$text\r\n";
            $check = 0;
        }
        else {
            # See if there is a custom reply for the command
            $text = $commandreply{$FTPCMD};
            if($text && ($text ne "")) {
                if($customcount{$FTPCMD} && (!--$customcount{$FTPCMD})) {
                    # used enough times so blank the custom command reply
                    $commandreply{$FTPCMD} = "";
                }

                sendcontrol $text;
                $check = 0;
            }
            else {
                # See if there is any display text for the command
                $text = $displaytext{$FTPCMD};
                if($text && ($text ne "")) {
                    if($proto eq 'imap') {
                        sendcontrol "$cmdid $text\r\n";
                    }
                    else {
                        sendcontrol "$text\r\n";
                    }

                    $check = 0;
                }

                # only perform this if we are not faking a reply
                my $func = $commandfunc{uc($FTPCMD)};
                if($func) {
                    &$func($FTPARG, $FTPCMD);
                    $check = 0;
                }
            }
        }

        if($check) {
            logmsg "$FTPCMD was not handled!\n";
            if($proto eq 'pop3') {
                sendcontrol "-ERR $FTPCMD is not dealt with!\r\n";
            }
            elsif($proto eq 'imap') {
                sendcontrol "$cmdid BAD $FTPCMD is not dealt with!\r\n";
            }
            else {
                sendcontrol "500 $FTPCMD is not dealt with!\r\n";
            }
        }

    } # while(1)
    logmsg "====> Client disconnected\n";

    if($serverlogslocked) {
        $serverlogslocked = 0;
        clear_advisor_read_lock($serverlogs_lockfile);
    }
}

killsockfilters($piddir, $proto, $ipvnum, $idnum, $verbose);
unlink($pidfile);
if($serverlogslocked) {
    $serverlogslocked = 0;
    clear_advisor_read_lock($serverlogs_lockfile);
}

exit;
