From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Mon, 8 Sep 2003 17:58:19 +0000 (+0000)
Subject: Scott A. Crosby believes in not disclosing
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=e67b9e528630fa842f677b067da8b404fc3914ab;p=p5sagit%2Fp5-mst-13.2.git

Scott A. Crosby believes in not disclosing
any more information than necessary: therefore
instead of hash_seed() we have now hashes_random().

p4raw-id: //depot/perl@21096
---

diff --git a/lib/Hash/Util.pm b/lib/Hash/Util.pm
index 8e8c952..7c528a2 100644
--- a/lib/Hash/Util.pm
+++ b/lib/Hash/Util.pm
@@ -7,7 +7,7 @@ use Carp;
 require Exporter;
 our @ISA        = qw(Exporter);
 our @EXPORT_OK  = qw(lock_keys unlock_keys lock_value unlock_value
-                     lock_hash unlock_hash hash_seed
+                     lock_hash unlock_hash hashes_random
                     );
 our $VERSION    = 0.05;
 
@@ -20,7 +20,7 @@ Hash::Util - A selection of general-utility hash subroutines
   use Hash::Util qw(lock_keys   unlock_keys
                     lock_value  unlock_value
                     lock_hash   unlock_hash
-                    hash_seed);
+                    hashes_random);
 
   %hash = (foo => 42, bar => 23);
   lock_keys(%hash);
@@ -33,7 +33,7 @@ Hash::Util - A selection of general-utility hash subroutines
   lock_hash  (%hash);
   unlock_hash(%hash);
 
-  my $hashes_are_randomised = hash_seed() != 0;
+  my $hashes_random = hashes_random();
 
 =head1 DESCRIPTION
 
@@ -179,18 +179,18 @@ sub unlock_hash (\%) {
 }
 
 
-=item B<hash_seed>
+=item B<hashes_random>
 
-    my $hash_seed = hash_seed();
+    my $hashes_random = hashes_random();
 
-hash_seed() returns the seed number used to randomise hash ordering.
-Zero means the "traditional" random hash ordering, non-zero means the
-new even more random hash ordering introduced in Perl 5.8.1.
+hashes_random() returns true if Perl hashes are randomised as in Perl
+5.8.1 and later, false if Perl hashes have a predictable order as in
+Perl 5.8.0 and earlier.
 
 =cut
 
-sub hash_seed () {
-    Internals::hash_seed();
+sub hashes_random () {
+    Internals::hashes_random();
 }
 
 =back
diff --git a/lib/Hash/Util.t b/lib/Hash/Util.t
index 7cffcbe..512f07c 100644
--- a/lib/Hash/Util.t
+++ b/lib/Hash/Util.t
@@ -6,7 +6,7 @@ BEGIN {
         chdir 't';
     }
 }
-use Test::More tests => 157;
+use Test::More tests => 155;
 use strict;
 
 my @Exported_Funcs;
@@ -274,5 +274,3 @@ like( $@, qr/^Attempt to access disallowed key 'I_DONT_EXIST' in a restricted ha
   }
 }
 
-my $hash_seed = hash_seed();
-ok($hash_seed >= 0, "hash_seed $hash_seed");
diff --git a/pod/perlrun.pod b/pod/perlrun.pod
index f8a0ae6..299cbf9 100644
--- a/pod/perlrun.pod
+++ b/pod/perlrun.pod
@@ -1140,13 +1140,17 @@ This means that each different run of Perl will have a different
 ordering of the results of keys(), values(), and each().
 
 See L<perlsec/"Algorithmic Complexity Attacks"> for more information,
-and also L</PERL_HASH_SEED>.
+and also L</PERL_HASH_SEED_DEBUG>.
 
 =item PERL_HASH_SEED_DEBUG
 
-(Since Perl 5.8.1.)  Set to "1" to display (to STDERR) the value of
-the hash seed at the beginning of execution.
-See also hash_seed() of L<Hash::Util>.
+(Since Perl 5.8.1.)  Set to one to display (to STDERR) the value of
+the hash seed at the beginning of execution.  B<Note that the hash
+seed is sensitive information>: by knowing it one can craft a
+denial-of-service attack against Perl code, even remotely, see
+L<perlsec/"Algorithmic Complexity Attacks"> for more information.
+B<Do not disclose the hash seed> to people who don't need to know it.
+See also hashes_random() of L<Hash::Util>.
 
 =item PERL_ROOT (specific to the VMS port)
 
diff --git a/universal.c b/universal.c
index 15c408d..dc9e253 100644
--- a/universal.c
+++ b/universal.c
@@ -187,7 +187,7 @@ XS(XS_Internals_SvREFCNT);
 XS(XS_Internals_hv_clear_placehold);
 XS(XS_PerlIO_get_layers);
 XS(XS_Regexp_DESTROY);
-XS(XS_Internals_hash_seed);
+XS(XS_Internals_hashes_random);
 
 void
 Perl_boot_core_UNIVERSAL(pTHX)
@@ -231,7 +231,7 @@ Perl_boot_core_UNIVERSAL(pTHX)
     newXSproto("PerlIO::get_layers",
                XS_PerlIO_get_layers, file, "*;@");
     newXS("Regexp::DESTROY", XS_Regexp_DESTROY, file);
-    newXSproto("Internals::hash_seed",XS_Internals_hash_seed, file, "");
+    newXSproto("Internals::hashes_random",XS_Internals_hashes_random, file, "");
 }
 
 
@@ -908,9 +908,9 @@ XS(XS_PerlIO_get_layers)
     XSRETURN(0);
 }
 
-XS(XS_Internals_hash_seed)
+XS(XS_Internals_hashes_random)
 {
     dXSARGS;
-    XSRETURN_UV(PL_hash_seed);
+    XSRETURN_IV(PL_hash_seed ? 1 : 0);
 }