Re: [PATCH v3] gitweb: redacted e-mail addresses feature.

> "Georgios Kontaxis via GitGitGadget" <gitgitgadget@gmail.com>
> writes:
>
>> From: Georgios Kontaxis <geko1702+commits@99rst.org>
>>
>> Gitweb extracts content from the Git log and makes it accessible
>> over HTTP. As a result, e-mail addresses found in commits are
>> exposed to web crawlers and they may not respect robots.txt.
>> This may result in unsolicited messages.
>> This is a feature for redacting e-mail addresses
>> from the generated HTML, etc. content.
>>
>> This feature does not prevent someone from downloading the
>> unredacted commit log, e.g., by cloning the repository, and
>> extracting information from it.
>> It aims to hinder the low-effort bulk collection of e-mail
>> addresses by web crawlers.
>
> Lines from here ...
>
>>
>> Changes since v1:
>> - Turned off the feature by default.
>> - Removed duplicate code.
>> - Added note about Gitweb consumers receiving redacted logs.
>>
>> Changes since v2:
>> - The feature can be set on a per-project basis. ('override' => 1)
>
> ... to here are to help reviewers on the mailing list while
> iterations of the same change is being reviewed and polished.
>
> But it is useless noise for those who only read "git log".  They
> simply do not have access to earlier iterations.
>
> Such "changes between iterations" comments needs to be written after
> the three-dash lines.
>
>> Signed-off-by: Georgios Kontaxis <geko1702+commits@99rst.org>
>> ---
>>     gitweb: Redacted e-mail addresses feature.
>>
>>     Gitweb extracts content from the Git log and makes it accessible
>> over
>>     HTTP. As a result, e-mail addresses found in commits are exposed to
>> web
>>     crawlers. This may result in unsolicited messages. This is a feature
>> for
>>     redacting e-mail addresses from the generated HTML content.
>>
>>     This feature does not prevent someone from downloading the
>> unredacted
>>     commit log and extracting information from it. It aims to hinder the
>>     low-effort bulk collection of e-mail addresses by web crawlers.
>>
>>     Signed-off-by: Georgios Kontaxis geko1702+commits@99rst.org
>>
>> Published-As:
>> https://github.com/gitgitgadget/git/releases/tag/pr-910%2Fkontaxis%2Fkontaxis%2Femail_privacy-v3
>> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git
>> pr-910/kontaxis/kontaxis/email_privacy-v3
>> Pull-Request: https://github.com/gitgitgadget/git/pull/910
>>
>> Range-diff vs v2:
>>
>>  1:  74af11ca8bf2 ! 1:  930cdefe7ee0 gitweb: redacted e-mail addresses
>> feature.
>>      @@ Commit message
>>           - Removed duplicate code.
>>           - Added note about Gitweb consumers receiving redacted logs.
>>
>>      +    Changes since v2:
>>      +    - The feature can be set on a per-project basis. ('override'
>> => 1)
>>      +
>>           Signed-off-by: Georgios Kontaxis <geko1702+commits@99rst.org>
>>
>>        ## Documentation/gitweb.conf.txt ##
>>      @@ gitweb/gitweb.perl: sub evaluate_uri {
>>       +	# $feature{'email_privacy'}{'default'} = [1];
>>       +	'email_privacy' => {
>>       +		'sub' => sub { feature_bool('email_privacy', @_) },
>>      -+		'override' => 0,
>>      ++		'override' => 1,
>>       +		'default' => [0]},
>>        );
>>
>>
>>
>>  Documentation/gitweb.conf.txt | 16 +++++++++++++
>>  gitweb/gitweb.perl            | 42 ++++++++++++++++++++++++++++++++---
>>  2 files changed, 55 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/gitweb.conf.txt
>> b/Documentation/gitweb.conf.txt
>> index 7963a79ba98b..b7af3240177d 100644
>> --- a/Documentation/gitweb.conf.txt
>> +++ b/Documentation/gitweb.conf.txt
>> @@ -896,6 +896,22 @@ same as of the snippet above:
>>  It is an error to specify a ref that does not pass "git
>> check-ref-format"
>>  scrutiny. Duplicated values are filtered.
>>
>> +email_privacy::
>> +    Redact e-mail addresses from the generated HTML, etc. content.
>> +    This hides e-mail addresses found in the commit log from web
>> crawlers.
>> +    Disabled by default.
>> ++
>> +It is highly recommended to enable this feature unless web crawlers are
>> +hindered in some other way. Note that crawlers intent on harvesting
>> e-mail
>> +addresses may disregard robots.txt.
>
> Up to this line is more-or-less OK, but with a few comments:
>
>  - "This hides ... from web crawlers"?  Doesn't this hide it
>    indiscriminately, whether the requester is an interactive
>    end-user or a crawler?
>

>  - The name of the configured feature, 'email_privacy'.  There is
>    another existing feature with underscore in its name
>    (remote_heads), but I think it is an odd-ball mistake we do not
>    want to imitate.  Instead, I think the "extra branch refs" may be
>    a good example to follow.  The feature name (written in Perl
>    code) is "extra-branch-refs" (downcased words with inter-word
>    dashes) and the corresponding configuration (I am not saying we
>    should add one to support this feature, if we do not have one
>    already) is "gitweb.extraBranchRefs" (camelCased words).
>

>> +---------------------------------------------------------------------------
>> +$feature{'email_privacy'}{'default'} = [1];
>> +---------------------------------------------------------------------------
>
> I do not think this should be here.  None of the boolean features
> listed early in "Features in `%feature`" section like blame,
> snapshot, grep, pickaxe, ... features tell readers how to enable a
> specific feature like that.
>
> Unless the syntax to configure a feature is one-off oddball that is
> different from all other features, we shouldn't clutter the
> description with an example like this.
>
> At the beginning of the section "Configuring Gitweb Features" there
> is a general description and that should be sufficient (and if it is
> not sufficient, it is OK to add an example to that section).
>

>> +Note that if Gitweb is not the final step in a workflow then subsequent
>> +steps may misbehave because of the redacted information they receive.
>
> In other words, this will break crawlers that expect email addresses
> are there and want to use it for some good purpose.  But that is an
> natural consequence of the "feature", and should be described as
> such when we said "Redact e-mail addresses", not as a "by the way"
> mention in a footnote.
>
> 	... after reading more, readers realize that the damage is
> 	far worse in the current incarnation of the patch, but let's
> 	read on ...
>

>> @@ -3449,6 +3458,19 @@ sub parse_date {
>>  	return %date;
>>  }
>>
>> +sub hide_mailaddr_if_private {
>> +	my $line = shift;
>> +	return $line unless (gitweb_check_feature('email_privacy') &&
>> +						$line =~ m/^([^<]+) <([^>]*)>/);
>
> I find that the second line is way too deeply indented.  Wouldn't
>
>> +	return $line unless (gitweb_check_feature('email_privacy') &&
>> +				$line =~ m/^([^<]+) <([^>]*)>/);
>
> be enough?
>

>> +	return hide_mailaddr($line)
>> +}
>> +
>> +sub hide_mailaddr {
>> +	my $mailaddr = shift;
>> +	$mailaddr =~ s/<([^>]*)>/<private>/;
>
> s/private/redacted/ perhaps?
>

>> @@ -3568,9 +3602,10 @@ sub parse_commit_text {
>>  	if (! defined $co{'title'} || $co{'title'} eq "") {
>>  		$co{'title'} = $co{'title_short'} = '(no commit message)';
>>  	}
>> -	# remove added spaces
>> +	# remove added spaces, redact e-mail addresses if applicable.
>>  	foreach my $line (@commit_lines) {
>>  		$line =~ s/^    //;
>> +		$line = hide_mailaddr_if_private($line);
>
> A commit log that ends with
>
> 	Thank you, A <a@example.com> and B <b@example.com>, for discovering
> 	this bug and quickly proposing a solution.
>
> would recact only the first one but not the other, I suspect.
>
> Much more problematic is that I see too many hits from:
>
>     $ git log v2.30.0..v2.31.0 | grep ' <[^>@]*>'
>
> That is, "find a line in the commit log message that has a SP, open <bra,
> run of characters that are not ket> or at@sign, closed with ket>".  These
> are clearly not e-mail addresses.
>
> This "feature" butchers a commit title:
>
>     mktag doc: say <hash> not <sha1>
>
> to
>
>     mktag doc: say <private> not <sha1>
>
> doesn't it?
>

>> @@ -8060,8 +8095,9 @@ sub git_commitdiff {
>>  		close $fd
>>  			or print "Reading git-diff-tree failed\n";
>>  	} elsif ($format eq 'patch') {
>> -		local $/ = undef;
>> -		print <$fd>;
>> +		while (my $line = <$fd>) {
>> +			print hide_mailaddr_if_private($line);
>> +		}
>
> And this is even worse.
>
>  $ git log -p --no-merges v2.30.0..v2.31.0 | grep ' <[^>@]*>' | wc -l
>
> gives me ~4700 hits.  Because the patch text as well as the log
> message is munged, the "feature" makes the output utterly unreliable
> as an input to "git am" by munging too much.  Interesting examples
> are like these:
>
>         -	for (i = 0; i < pairs->nr; ++i) {
>                 'git <command> [<revision>...] -- [<file>...]'
>         +	for (i = split; i < geometry->pack_nr; i++) {
>
> Now, I am *NOT* saying that you should tighten the e-mail address
> syntax detection and keep munging the patch text.  The lines that
> begin with minus and SP in a patch must match the preimage text,
> so munging out existing e-mail addresses from them will make the
> patch fail to find the part that needs to be modified.  And
> replacing an e-mail address on a line that begins with plus would
> redact it from the source---if they wrote an address, they must have
> meant it to be available to those who consume the source, so I doubt
> the wisdom of munging the patch part at all.
>
> I may be sympathetic to the cause of the patch, but, I do not agree
> with its execution in this iteration of the patch.
>