v2: improve deduplication checks

[public-inbox.git] / lib / PublicInbox / ContentId.pm

diff --git a/lib/PublicInbox/ContentId.pm b/lib/PublicInbox/ContentId.pm
index d1a009e77f2ed9e9e8b4de30a79f85a706ef37e8..b1d27eb8e48a8e835c0d088f77e84f3a7e38dd88 100644 (file)
--- a/lib/PublicInbox/ContentId.pm
+++ b/lib/PublicInbox/ContentId.pm
@@ -5,19 +5,24 @@ package PublicInbox::ContentId;
 use strict;
 use warnings;
 use base qw/Exporter/;
-our @EXPORT_OK = qw/content_id/;
+our @EXPORT_OK = qw/content_id content_digest/;
 use PublicInbox::MID qw(mids references);
+use PublicInbox::MsgIter;
 
 # not sure if less-widely supported hash families are worth bothering with
 use Digest::SHA;
 
-# Content-* headers are often no-ops, so maybe we don't need them
-my @ID_HEADERS = qw(Subject From Date To Cc);
+sub digest_addr ($$$) {
+       my ($dig, $h, $v) = @_;
+       $v =~ tr/"//d;
+       $v =~ s/@([a-z0-9\_\.\-\(\)]*([A-Z])\S*)/'@'.lc($1)/ge;
+       utf8::encode($v);
+       $dig->add("$h\0$v\0");
+}
 
-sub content_id ($;$) {
-       my ($mime, $alg) = @_;
-       $alg ||= 256;
-       my $dig = Digest::SHA->new($alg);
+sub content_digest ($) {
+       my ($mime) = @_;
+       my $dig = Digest::SHA->new(256);
        my $hdr = $mime->header_obj;
 
        # References: and In-Reply-To: get used interchangeably
@@ -25,19 +30,73 @@ sub content_id ($;$) {
        # in SearchIdx, so treat them the same for this:
        my %seen;
        foreach my $mid (@{mids($hdr)}) {
-               $dig->add('mid: '.$mid);
+               # do NOT consider the Message-ID as part of the content_id
+               # if we got here, we've already got Message-ID reuse
                $seen{$mid} = 1;
        }
        foreach my $mid (@{references($hdr)}) {
                next if $seen{$mid};
-               $dig->add('ref: '.$mid);
+               $dig->add("ref\0$mid\0");
+       }
+
+       # Only use Sender: if From is not present
+       foreach my $h (qw(From Sender)) {
+               my @v = $hdr->header($h);
+               if (@v) {
+                       digest_addr($dig, $h, $_) foreach @v;
+               }
        }
-       foreach my $h (@ID_HEADERS) {
-               my @v = $hdr->header_raw($h);
-               $dig->add("$h: $_") foreach @v;
+       foreach my $h (qw(Subject Date)) {
+               my @v = $hdr->header($h);
+               foreach my $v (@v) {
+                       utf8::encode($v);
+                       $dig->add("$h\0$v\0");
+               }
        }
-       $dig->add($mime->body_raw);
-       'SHA-' . $dig->algorithm . ':' . $dig->hexdigest;
+       # Some mail processors will add " to unquoted names that were
+       # not in the original message.  For the purposes of deduplication,
+       # do not take it into account:
+       foreach my $h (qw(To Cc)) {
+               my @v = $hdr->header($h);
+               digest_addr($dig, $h, $_) foreach @v;
+       }
+       msg_iter($mime, sub {
+               my ($part, $depth, @idx) = @{$_[0]};
+               $dig->add("\0$depth:".join('.', @idx)."\0");
+               my $fn = $part->filename;
+               if (defined $fn) {
+                       utf8::encode($fn);
+                       $dig->add("fn\0$fn\0");
+               }
+               my @d = $part->header('Content-Description');
+               foreach my $d (@d) {
+                       utf8::encode($d);
+                       $dig->add("d\0$d\0");
+               }
+               $dig->add("b\0");
+               my $ct = $part->content_type || 'text/plain';
+               my $s = eval { $part->body_str };
+               if ($@ && $ct =~ m!\btext/plain\b!i) {
+                       # Try to assume UTF-8 because Alpine
+                       # seems to do wacky things and set
+                       # charset=X-UNKNOWN
+                       $part->charset_set('UTF-8');
+                       $s = eval { $part->body_str };
+               }
+               if (defined $s) {
+                       $s =~ s/\r\n/\n/gs;
+                       $s =~ s/\s*\z//s;
+                       utf8::encode($s);
+               } else {
+                       $s = $part->body;
+               }
+               $dig->add($s);
+       });
+       $dig;
+}
+
+sub content_id ($) {
+       content_digest($_[0])->digest;
 }
 
 1;