gzipfilter: drop HTTP connection on bugs or data corruption

While all the {async_next} callbacks needed eval guards anyways
because of DS->write, {async_eml} callbacks did not.

Ensure any bugs in our code or data corruption result in
termination of the HTTP connection, so as not to leave clients
hanging on a response which never comes or is mangled in some
way.

1 files changed, 19 insertions, 3 deletions

diff --git a/lib/PublicInbox/GzipFilter.pm b/lib/PublicInbox/GzipFilter.pm
index d72ad3c8..57344604 100644
--- a/lib/PublicInbox/GzipFilter.pm
+++ b/lib/PublicInbox/GzipFilter.pm
@@ -147,18 +147,34 @@ sub close {
         }
 }
 
+sub bail  {
+        my $self = shift;
+        if (my $env = $self->{env}) {
+                eval { $env->{'psgi.errors'}->print(@_, "\n") };
+                warn("E: error printing to psgi.errors: $@", @_) if $@;
+                my $http = $env->{'psgix.io'} or return; # client abort
+                eval { $http->close }; # should hit our close
+                warn "E: error in http->close: $@" if $@;
+                eval { $self->close }; # just in case...
+                warn "E: error in self->close: $@" if $@;
+        } else {
+                warn @_, "\n";
+        }
+}
+
 # this is public-inbox-httpd-specific
 sub async_blob_cb { # git->cat_async callback
         my ($bref, $oid, $type, $size, $self) = @_;
         my $http = $self->{env}->{'psgix.io'} or return; # client abort
-        my $smsg = $self->{smsg} or die 'BUG: no smsg';
+        my $smsg = $self->{smsg} or bail($self, 'BUG: no smsg');
         if (!defined($oid)) {
                 # it's possible to have TOCTOU if an admin runs
                 # public-inbox-(edit|purge), just move onto the next message
                 return $http->next_step($self->{async_next});
         }
-        $smsg->{blob} eq $oid or die "BUG: $smsg->{blob} != $oid";
-        $self->{async_eml}->($self, PublicInbox::Eml->new($bref));
+        $smsg->{blob} eq $oid or bail($self, "BUG: $smsg->{blob} != $oid");
+        eval { $self->{async_eml}->($self, PublicInbox::Eml->new($bref)) };
+        bail($self, "E: async_eml: $@") if $@;
         $http->next_step($self->{async_next});
 }