setup/serviceslint

   1 #!/usr/bin/perl
   2 #
   3 # Perform sanity checks on the services file, supplied as argument.
   4 # Based on an earlier shell script of the same name, but much faster,
   5 # and it also detects actual errors in the current services file :)
   6 #
   7 # This program includes a manual, run "perldoc serviceslint" to see it.
   8 #
   9
  10 use strict;
  11 use warnings;
  12
  13 die "Usage: $0 /etc/services\n" unless $#ARGV == 0;
  14
  15 # Build a hash of known protocols
  16 my %protocol;
  17 open FH, "protocols" or die "cannot open protocols: $!\n";
  18 while (<FH>) {
  19         chomp;
  20         s/#.*$//;
  21         my ($name, $port) = m/([\S]+)\s+(\d+)/ or next;
  22         $protocol{$name} = $port;
  23 }
  24 close FH;
  25
  26 # Parse the supplied services file
  27 my $retval = 0;
  28 my $line = 0;
  29 my %service;
  30 open FH, $ARGV[0] or die "cannot open $ARGV[0]: $!\n";
  31 while (<FH>) {
  32         $line++;                                    # Keep a line count
  33         chomp;                                      # Remove CR/LF chars
  34         if (m/^\s+/) {
  35                 print "Malformed line $line\n";     # No leading whitespace
  36                 $retval = 1;
  37                 next;
  38         }
  39         s/\s*#.*$//;                                # Strip out comments
  40         next if m/^$/;                              # Skip empty lines
  41         my ($name, $port, $proto, $aliases) =       # Primary pattern match
  42                 m/^([\S]+)\s+(\d+)\/(\w+)\s*(.*)/
  43                 or die "Malformed line: $line\n";
  44         if (not exists $protocol{$proto}) {
  45                 print "Bad protocol at line $line: $proto\n";
  46                 $retval = 1;
  47         }
  48         if (exists $service{$proto}{$port}) {
  49                 print "Duplicate port at line $line: $port/$proto\n";
  50                 $retval = 1;
  51         }
  52         $service{$proto}{$port} = $name;
  53         foreach ($name, split /\s+/, $aliases) {
  54                 if (exists $service{$proto}{$_}) {
  55                         print "Duplicate name at line $line: $_/$proto\n";
  56                         $retval = 1;
  57                 }
  58                 $service{$proto}{$_} = $port;
  59         };
  60
  61 }
  62 close FH;
  63 exit $retval;
  64
  65 __END__
  66
  67 =head1 NAME
  68
  69 serviceslint - perform verification on the /etc/services file
  70
  71 =head1 SYNOPSIS
  72
  73 B<serviceslint> I<filename>
  74
  75 =head1 DESCRIPTION
  76
  77 The B<serviceslint> command performs syntax and content checks on the
  78 given filename, normally a copy of the I</etc/services> file.
  79
  80 Syntax checking consists of a regular expression applied to
  81 non-empty, non-comment lines.  If the syntax check fails, then
  82 the program prints a message and aborts with non-zero status code.
  83
  84 Content checking detects various kinds of duplicate entries.
  85 Currently, warnings are printed for duplicate entries, but execution
  86 continues, and the program I<exits with status code zero> (eg. success).
  87
  88 =over
  89
  90 =item B<Malformed line> I<NNN>
  91
  92 The specified line has invalid syntax.  Note that leading whitespace
  93 is not permitted.  Non-empty lines must begin with a comment, or with
  94 a service name followed by a port number / protocol pair.
  95
  96 =item B<Duplicate port at line> I<NNN>
  97
  98 Occurs when a port number / protocol pair is found more than once
  99 in the services file.  The warning is flagged on the second (and any
 100 subsequent) occurrences.  These entries will not be found via the
 101 B<getservbyport()> function.
 102
 103 =item B<Duplicate name at line> I<NNN>
 104
 105 Occurs when a service name, or alias, occurs more than once in the
 106 services file.  The warning is flagged on the second (and subsequent)
 107 occurrence.  These entries will not be returned by the B<getservbyname()>
 108 function.
 109
 110 =back
 111
 112 =head1 SEE ALSO
 113
 114 The services(5) man page describes the file format.
 115
 116 =head1 AUTHOR
 117
 118 Ralph Siemsen & Phil Knirsch
 119