uninitialized warning issued when stringifying a request

[karenetheridge]

What am I doing wrong here? This seems like a warning that shouldn't happen...

use strict;
use warnings;
use Mojo::Message::Request;
use Data::Dumper;

my $req = Mojo::Message::Request->new->error({ message => 'error' });
print STDERR "### req is ", Dumper($req);

my $str = $req->to_string;
print STDERR "### got string\n$str\n";

produces:

### req is $VAR1 = bless( {
                 'error' => {
                              'message' => 'error'
                            },
                 'finished' => 1,
                 'events' => {},
                 'state' => 'finished'
               }, 'Mojo::Message::Request' );
Use of uninitialized value $_ in concatenation (.) or string at /Volumes/chambord/Users/ether/.perlbrew/libs/41.7@std/lib/perl5/Mojo/Headers.pm line 181.
### got string
GET / HTTP/1.1
Host: 

This is with Mojolicious 9.39.

[karenetheridge]

The undef warning is coming from the host header being undef. I can't find where in the code this header is being set; the first place I've identified where it is set is here:

### in Mojo::Content get_header_chunk, self is $VAR1 = bless( {
                 'asset' => bless( {
                                     'auto_upgrade' => 1
                                   }, 'Mojo::Asset::Memory' ),
                 'body_size' => 0,
                 'events' => {
                               'read' => [
                                           sub { "DUMMY" }
                                         ]
                             },
                 'headers' => bless( {
                                       'headers' => {
                                                      'host' => [
                                                                  undef
                                                                ]
                                                    }
                                     }, 'Mojo::Headers' ),
                 'read' => $VAR1->{'events'}{'read'}[0]
               }, 'Mojo::Content::Single' );

..but earlier, in Mojo::Message::fix_headers, host is not set.

[s1037989]

According to spec, a host header must be sent with all http 1.1 requests.. I reckon Mojo is following spec somewhere -- like you, I'm curious to learn where!

[guest20]

The pod shows two ways to construct Mojo::Requests and they're both methods named "parse"... One that takes a url and one that takes http.

A request without a url sounds like a zen kōan

[karenetheridge]

If I do $req->headers->host(''); there is still a warning, but then this change is enough to fix it:

diff --git a/lib/Mojo/Message/Request.pm b/lib/Mojo/Message/Request.pm
index c2b12398d..99b272707 100644
--- a/lib/Mojo/Message/Request.pm
+++ b/lib/Mojo/Message/Request.pm
@@ -73,7 +73,7 @@ sub fix_headers {
 
   # Host
   my $url = $self->url;
-  $headers->host($url->host_port) unless $headers->host;
+  $headers->host($url->host_port) unless defined $headers->host;
 
   # Basic authentication
   if ((my $info = $url->userinfo) && !$headers->authorization) {

[karenetheridge]

By my reading of https://www.rfc-editor.org/rfc/rfc9112.html#section-3.2-5, a Host header is mandatory, but an empty value is permissible. Therefore we should be doing a definedness check (as in the patch above), not a truthy check. (0 is also a weird, but valid, Host value, which is also currently excluded.)

fix_headers() could also set the Host header to '' if it is not already set.

[kraih]

Seems reasonable.