From 1f29b33d3f71b8a40f5ae76bf20b95618b518654 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Wed, 18 May 2016 01:23:05 +0000
Subject: unsubscribe: get off mah lawn^H^H^Hist

While public-inbox is intended primarily for archival,
SMTP list subscriptions are still in use in most places
and users are likely to want a good unsubscribe mechanism.

HTTP (or HTTPS) links in the List-Unsubscribe header are
often preferable since some users may use an incorrect
email address for mailto: links.

Thus, it is useful to provide an example which generates an
HTTPS link for users to click on.  The default .psgi requires
a POST confirmation (as destructive actions with GET are
considered bad practice).  However, the "confirm" parameter
may be disabled for a true "one-click" unsubscribe.

The generated URLs are hopefully short enough and both shell
and highlighting-friendly to reduce copy+paste errors.
---
 examples/unsubscribe.psgi | 68 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 examples/unsubscribe.psgi

(limited to 'examples/unsubscribe.psgi')

diff --git a/examples/unsubscribe.psgi b/examples/unsubscribe.psgi
new file mode 100644
index 00000000..82e186b1
--- /dev/null
+++ b/examples/unsubscribe.psgi
@@ -0,0 +1,68 @@
+#!/usr/bin/perl -w
+# Copyright (C) 2016 all contributors <meta@public-inbox.org>
+# License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
+# This should not require any other PublicInbox code, but may use
+# PublicInbox::Config if ~/.public-inbox/config exists or
+# PI_CONFIG is pointed to an appropriate location
+use strict;
+use Plack::Builder;
+use PublicInbox::Unsubscribe;
+my $app = PublicInbox::Unsubscribe->new(
+	pi_config => eval { # optional, for pointing out archives
+		require PublicInbox::Config;
+		# uses ~/.public-inbox/config by default,
+		# can override with PI_CONFIG or here since
+		# I run this .psgi as the mlmmj user while the
+		# public-inbox-mda code which actually writes to
+		# the archives runs as a different user.
+		PublicInbox::Config->new('/home/pi/.public-inbox/config')
+	},
+	code_url => 'git://80x24.org/public-inbox.git', # change if you fork
+	owner_email => 'BOFH@example.com',
+	confirm => 1,
+
+	# First 8 bytes is for the key, next 8 bytes is for the IV
+	# using Blowfish.  We want as short URLs as possible to avoid
+	# copy+paste errors
+	# umask 077 && dd if=/dev/urandom bs=16 count=1 of=.unsubscribe.key
+	key_file => '/home/mlmmj/.unsubscribe.key',
+
+	# this runs as whatever user has perms to run /usr/bin/mlmmj-unsub
+	# users of other mailing lists.  Returns '' on success.
+	unsubscribe => sub {
+		my ($user_addr, $list_addr) = @_;
+
+		# map list_addr to mlmmj spool, I use:
+		# /home/mlmmj/spool/$LIST here
+		my ($list, $domain) = split('@', $list_addr, 2);
+		my $spool = "/home/mlmmj/spool/$list";
+
+		return "Invalid list: $list" unless -d $spool;
+
+		# -c to send a confirmation email, -s is important
+		# in case a user is click-happy and clicks twice.
+		my @cmd = (qw(/usr/bin/mlmmj-unsub -c -s),
+				'-L', $spool, '-a', $user_addr);
+
+		# we don't know which version they're subscribed to,
+		# try both non-digest and digest
+		my $normal = system(@cmd);
+		my $digest = system(@cmd, '-d');
+
+		# success if either succeeds:
+		return '' if ($normal == 0 || $digest == 0);
+
+		# missing executable or FS error,
+		# otherwise -s always succeeds, right?
+		return 'Unknown error, contact admin';
+	},
+);
+
+builder {
+	mount '/u' => builder {
+		eval { enable 'Deflater' }; # optional
+		eval { enable 'ReverseProxy' }; # optional
+		enable 'Head';
+		sub { $app->call(@_) };
+	};
+};
-- 
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