#!/usr/bin/perl

#

#  Reformat 'snmpcmd -d' style raw dump output

#    into something a little easier to understand.

#

sub parse_dump {

    #

    #  Basic formatting technique:

    #     Display the contents of each nested SEQUENCE

    #        indented from the enclosing level.

    #     Individual data fields are all on one line

    #

    my @data    = @_;

    my $indent  = shift( @data );

    my $datalen = shift( @data );

    while ( $datalen > 0 ) {

        my ($tag, $tlen, $tmp);

        my ($tag1, $tag2 );

        $tag  = shift( @data );

        $tmp  = shift( @data );

        $tlen = hex($tmp);

        #

        # Handle 2-octet lengths

        if ( $tlen >= 128 ) {

            $tlen -= 128;

            $tmp   = shift( @data );

            $tlen += hex($tmp);

        }

        $datalen -= ($tlen + 2 );

        $tag1 = substr($tag, 0, 1);

        $tag2 = substr($tag, 1, 1);

        #

        # Sequence-based tags - display and indent

        #

        if ( $tag1 eq 3 ) {

            print " "x$indent, "$tag $tmp\n";

            parse_dump( $indent+3, $tlen, @data );

        }

        elsif ( $tag1 eq "A" ) {

            print " "x$indent, "$tag $tmp\n";

            parse_dump( $indent+3, $tlen, @data );

        }

        #

        # Leaf-data tags - just display

        #

        else {

            $val = "";

            while ( $tlen > 0 ) {

               $val .= " ";

               $val .= shift( @data );

               $tlen--;

            }

            if ( $tag1 eq "0" ) {     # leaf data

                print " "x$indent, "$tag $tmp$val\n";

            }

            elsif ( $tag1 eq "8" ) {  # exceptions

                print " "x$indent, "$tag $tmp$val\n";

            }

            else {                    # unknown

                print " "x$indent, "$tag $tmp$val\n";

            }

        }

    }

}

$inpacket=0;

$rawdump="";

while (<>) {

    if ( $inpacket ) {

        #

        # Strip off the extraneous junk, and join

        #   the raw dump output into a single line

        #

        if ( /^[0-9]*: / ) {

            chomp;

            s/^[0-9]*: //;

            s/   .*$//;

            s/  / /g;

            $rawdump = "$rawdump $_";

        } else {

            #

            # Once this line is complete, display the

            #   dump in a vaguely sensible layout

            #

            @rawdata = split( " ", $rawdump );

            parse_dump( 3, $#rawdata, @rawdata );

            $inpacket=0;

            $rawdump="";

        }

    } else {

        #

        # Pass everything else through untouched

        #

        print;

        if ( /^Sending / || /^Received / ) {

            $inpacket=1;

            $rawdump="";

        }

    }

}