eml: enforce a maximum header length

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

diff --git a/lib/PublicInbox/Eml.pm b/lib/PublicInbox/Eml.pm
index f022516c12cd091cd2ee6bc77212208f399b7522..2ccbb6597de406680376ad9a02a419ee53d1015b 100644 (file)
--- a/lib/PublicInbox/Eml.pm
+++ b/lib/PublicInbox/Eml.pm
@@ -41,6 +41,7 @@ $PublicInbox::EmlContentFoo::STRICT_PARAMS = 0;
 our $MAXPARTS = 1000; # same as SpamAssassin
 our $MAXDEPTH = 20; # seems enough, Perl sucks, here
 our $MAXBOUNDLEN = 2048; # same as postfix
+our $header_size_limit = 102400; # same as postfix
 
 my %MIME_ENC = (qp => \&enc_qp, base64 => \&encode_base64);
 my %MIME_DEC = (qp => \&dec_qp, base64 => \&decode_base64);
@@ -68,6 +69,22 @@ sub re_memo ($) {
                                        /ismx
 }
 
+sub hdr_truncate ($) {
+       my $len = length($_[0]);
+       substr($_[0], $header_size_limit, $len) = '';
+       my $end = rindex($_[0], "\n");
+       if ($end >= 0) {
+               ++$end;
+               substr($_[0], $end, $len) = '';
+               warn "header of $len bytes truncated to $end bytes\n";
+       } else {
+               $_[0] = '';
+               warn <<EOF
+header of $len bytes without `\\n' within $header_size_limit ignored
+EOF
+       }
+}
+
 # compatible with our uses of Email::MIME
 sub new {
        my $ref = ref($_[1]) ? $_[1] : \(my $cpy = $_[1]);
@@ -81,14 +98,18 @@ sub new {
                # likely on *nix
                my $hdr = substr($$ref, 0, $pos + 2, ''); # sv_chop on $$ref
                chop($hdr); # lower SvCUR
+               hdr_truncate($hdr) if length($hdr) > $header_size_limit;
                bless { hdr => \$hdr, crlf => "\n", bdy => $ref }, __PACKAGE__;
        } elsif ($$ref =~ /\r?\n(\r?\n)/s) {
                my $hdr = substr($$ref, 0, $+[0], ''); # sv_chop on $$ref
                substr($hdr, -(length($1))) = ''; # lower SvCUR
+               hdr_truncate($hdr) if length($hdr) > $header_size_limit;
                bless { hdr => \$hdr, crlf => $1, bdy => $ref }, __PACKAGE__;
        } elsif ($$ref =~ /^[a-z0-9-]+[ \t]*:/ims && $$ref =~ /(\r?\n)\z/s) {
                # body is optional :P
-               bless { hdr => \($$ref), crlf => $1 }, __PACKAGE__;
+               my $hdr = substr($$ref, 0, $header_size_limit + 1);
+               hdr_truncate($hdr) if length($hdr) > $header_size_limit;
+               bless { hdr => \$hdr, crlf => $1 }, __PACKAGE__;
        } else { # nothing useful
                my $hdr = $$ref = '';
                bless { hdr => \$hdr, crlf => "\n" }, __PACKAGE__;