# This program is copyright 2011 Baron Schwartz, 2011 Percona Inc.
# Feedback and improvements are welcome.
#
# THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
# WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
# MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation, version 2; OR the Perl Artistic License.  On UNIX and similar
# systems, you can issue `man perlgpl' or `man perlartistic' to read these
# licenses.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 59 Temple
# Place, Suite 330, Boston, MA  02111-1307  USA.
# ###########################################################################
# SimpleTCPDumpParser package
# ###########################################################################
{
# Package: SimpleTCPDumpParser
# SimpleTCPDumpParser parses simple tcpdump output.
package SimpleTCPDumpParser;

use strict;
use warnings FATAL => 'all';
use English qw(-no_match_vars);
use constant PTDEBUG => $ENV{PTDEBUG} || 0;

use Time::Local qw(timelocal);
use Data::Dumper;
$Data::Dumper::Indent    = 1;
$Data::Dumper::Sortkeys  = 1;
$Data::Dumper::Quotekeys = 0;

# Required arguments: watch
sub new {
   my ( $class, %args ) = @_;
   my ($ip, $port) = split(/:/, $args{watch});
   my $self = {
      sessions => {},
      requests => 0,
      port     => $port || 3306,
   };
   return bless $self, $class;
}

# This method accepts an open filehandle and callback functions.  It reads
# events from the filehandle and calls the callbacks with each event.  $misc is
# some placeholder for the future and for compatibility with other query
# sources.
#
# The input is TCP requests and responses, such as the following:
#
# 2011-04-04 18:57:43.804195 IP 10.10.18.253.58297 > 10.10.18.40.3306: tcp 132
# 2011-04-04 18:57:43.804465 IP 10.10.18.40.3306 > 10.10.18.253.58297: tcp 2920
#
# Each event is a hashref of attribute => value pairs such as the following:
#
#  my $event = {
#     id   => '0',                  # Sequentially assigned ID, in arrival order
#     ts   => '1301957863.804195',  # Start timestamp
#     ts0  => ...................   # First start timestamp
#     end  => '1301957863.804465',  # End timestamp
#     end1 => ...................   # Second end timestamp
#     arg  => undef,                # For compatibility with other modules
#     host => '10.10.18.253',       # Host IP address where the event came from
#     port => '58297',              # TCP port where the event came from
#     ...                           # Other attributes
#  };
#
# The first and second start/end timestamps are illustrated in this timeline:
#
# |<--request-->|........processing time.........|<--response-->|
# ts0           ts                               end            end1
#
# Normally we probably want to measure the response time from ts to end, but in
# some cases we are interested in different ways of measuring it.
#
# TCP requests and responses form "sessions", which can be in one of these
# statuses:
#  [Q]uerying     - The remote host is sending the query to the server.
#  [R]esponding   - The server is replying back to the remote host.
sub parse_event {
   my ( $self, %args ) = @_;
   my @required_args = qw(next_event tell);
   foreach my $arg ( @required_args ) {
      die "I need a $arg argument" unless $args{$arg};
   }
   my ($next_event, $tell) = @args{@required_args};

   my $sessions   = $self->{sessions};
   my $pos_in_log = $tell->();
   my $line;

   EVENT:
   while ( defined($line = $next_event->()) ) {
      # Split the line into timestamp, source, and destination
      my ( $ts, $us, $src, $dst )
         = $line =~ m/([0-9-]{10} [0-9:]{8})(\.\d{6}) IP (\S+) > (\S+):/;
      next unless $ts;
      my $unix_timestamp = make_ts($ts) . $us;

      # If it's an inbound packet, we record this as the beginning of a request.
      # But, if there's an existing session from the $src, and that session is
      # in "[R]esponding" status, then this must be the beginning of the *next*
      # request from that $src.  Therefore we need to finish that request and
      # emit an event, then forget the earlier request.
      if ( $dst =~ m/\.$self->{port}$/o ) {
         my $event;
         if ( exists $sessions->{$src} && $sessions->{$src}->{status} eq 'R' ) {
            # Make the event, which we'll return later.
            $event = $self->make_event($src);
         }
         if ( exists $sessions->{$src} ) {
            $sessions->{$src}->{ts} = $unix_timestamp;
         }
         else {
            $sessions->{$src} ||= {
               pos_in_log => $pos_in_log,
               ts         => $unix_timestamp,
               ts0        => $unix_timestamp,
               id         => $self->{requests}++,
               status     => 'Q',
            };
         }
         return $event if $event;
      }

      # If it's a reply to an inbound request, then we simply record the
      # timestamp of the reply packet.
      elsif (defined (my $event = $sessions->{$dst}) ) {
         $event->{status} = 'R',
         $event->{end}  ||= $unix_timestamp;
         $event->{end1}   = $unix_timestamp;
      }
      $pos_in_log = $tell->();
   } # EVENT

   # There are probably events that have not been emitted because there's been
   # no subsequent inbound packet from that source host/port.  Make and emit
   # these.  We just loop over the source host/port and make events (which might
   # not do anything but delete a session if no response has been seen yet)
   # until we get one, which we return.
   foreach my $src ( keys %$sessions ) {
      my $event = $self->make_event($src);
      return $event if $event;
   }

   $args{oktorun}->(0) if $args{oktorun};
   return;
}

# Given a key into the sessions hash, makes and returns an event.  If the
# session isn't complete (hasn't been replied to yet), returns undef.
sub make_event {
   my ( $self, $src ) = @_;
   my $event = $self->{sessions}->{$src};
   delete $self->{sessions}->{$src};
   if ( $event->{status} eq 'R' ) {
      my ( $src_host, $src_port ) = $src =~ m/^(.*)\.(\d+)$/;
      $event->{host} = $src_host;
      $event->{port} = $src_port;
      $event->{arg}  = undef;
      delete $event->{status};
      PTDEBUG && _d('Properties of event:', Dumper($event));
      return $event;
   }
   return undef;
}

# Function to memo-ize and cache repeated calls to timelocal.  Accepts a string,
# outputs an integer.
{
   my ($last, $result);
   # $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
   sub make_ts {
      my ($arg) = @_;
      if ( !$last || $last ne $arg ) {
         my ($year, $mon, $mday, $hour, $min, $sec) = split(/\D/, $arg);
         $result = timelocal($sec, $min, $hour, $mday, $mon - 1, $year);
         $last   = $arg;
      }
      return $result;
   }
}

sub _d {
   my ($package, undef, $line) = caller 0;
   @_ = map { (my $temp = $_) =~ s/\n/\n# /g; $temp; }
        map { defined $_ ? $_ : 'undef' }
        @_;
   print STDERR "# $package:$line $PID ", join(' ', @_), "\n";
}

1;
}
# ###########################################################################
# End SimpleTCPDumpParser package
# ###########################################################################
