UCW::CGI: Report all errors by proper HTTP status codes

All calls to die have been replaced by returning a proper HTTP status
code. (A sole exception is if we fail, because we were not run as a CGI
script at all.)

Also, the set of supported HTTP methods now includes HEAD.

diff --git a/ucw/perl/UCW/CGI.pm b/ucw/perl/UCW/CGI.pm
index a4c5812d9129d0bbabd607218834c39aa806f55a..c8ec08db22666699ea52207b87372d3561ef8faa 100644 (file)
--- a/ucw/perl/UCW/CGI.pm
+++ b/ucw/perl/UCW/CGI.pm
@@ -6,10 +6,6 @@
 #      This software may be freely distributed and used according to the terms
 #      of the GNU Lesser General Public License.
 
-# FIXME:
-# - respond with proper HTTP error codes
-# - if we get invalid parameters, generate HTTP error or redirect
-
 package UCW::CGI;
 
 # First of all, set up error handling, so that even errors during parsing
@@ -62,6 +58,12 @@ our @EXPORT_OK = qw();
 
 our $utf8_mode = 0;
 
+sub http_error($;@) {
+       my $err = shift @_;
+       print join("\n", "Status: $err", "Content-Type: text/plain", @_, "", $err, "");
+       exit;
+}
+
 ### Escaping ###
 
 sub url_escape($) {
@@ -174,20 +176,22 @@ sub init_args() {
        if (my $qs = $ENV{"QUERY_STRING"}) {
                parse_raw_args($qs);
        }
-       if ($method eq "GET") {
+       if ($method eq "GET" || $method eq "HEAD") {
        } elsif ($method eq "POST") {
-               if ($ENV{"CONTENT_TYPE"} =~ /^application\/x-www-form-urlencoded\b/i) {
+               my $content_type = $ENV{"CONTENT_TYPE"} // "";
+               if ($content_type =~ /^application\/x-www-form-urlencoded\b/i) {
                        while (<STDIN>) {
                                chomp;
                                parse_raw_args($_);
                        }
-               } elsif ($ENV{"CONTENT_TYPE"} =~ /^multipart\/form-data\b/i) {
+               } elsif ($content_type =~ /^multipart\/form-data\b/i) {
                        parse_multipart_form_data();
                } else {
-                       die "Unknown content type for POST data";
+                       http_error "415 Unsupported Media Type";
+                       exit;
                }
        } else {
-               die "Unknown request method";
+               http_error "405 Method Not Allowed", "Allow: GET, HEAD, PUT";
        }
 }
 
@@ -288,13 +292,13 @@ sub get_mp_line($) {
                        return undef;
                }
        } else {
-               die "Premature end of multipart POST data";
+               http_error "400 Bad Request: Premature end of multipart POST data";
        }
 }
 
 sub skip_mp_boundary() {
        if ($mp_buffer_boundary != $mp_buffer_i) {
-               die "Premature end of multipart POST data";
+               http_error "400 Bad Request: Premature end of multipart POST data";
        }
        $mp_buffer_boundary = -1;
        $mp_buffer_i += 2;
@@ -334,7 +338,7 @@ sub parse_multipart_form_data() {
        # First of all, find the boundary string
        my $ct = rfc822_prepare($ENV{"CONTENT_TYPE"});
        if (!(($boundary) = ($ct =~ /^.*;\s*boundary=([^; ]+)/))) {
-               die "Multipart content with no boundary string received";
+               http_error "400 Bad Request: Multipart content with no boundary string received";
        }
        $boundary = rfc822_deescape($boundary);
        print STDERR "BOUNDARY IS $boundary\n" if $debug;
@@ -353,7 +357,7 @@ sub parse_multipart_form_data() {
                        $max_allowed += $a->{"maxsize"} || 65536;
                }
                if ($size > $max_allowed) {
-                       die "Maximum form data length exceeded";
+                       http_error "413 Request Entity Too Large";
                }
        }
 
@@ -378,7 +382,9 @@ sub parse_multipart_form_data() {
                    (($field) = ($cdisp =~ /;name=([^;]+)/)) &&
                    ($a = $main_arg_table->{"$field"})) {
                        print STDERR "FIELD $field\n" if $debug;
-                       if (defined $h->{"content-transfer-encoding"}) { die "Unexpected Content-Transfer-Encoding"; }
+                       if (defined $h->{"content-transfer-encoding"}) {
+                               http_error "400 Bad Request: Unexpected Content-Transfer-Encoding";
+                       }
                        if (defined $a->{"var"}) {
                                while (defined (my $l = get_mp_line(1))) {
                                        print STDERR "VALUE $l\n" if $debug;
@@ -400,7 +406,7 @@ sub parse_multipart_form_data() {
                                        print $fh substr($mp_buffer, $mp_buffer_i, $i);
                                        $mp_buffer_i += $i;
                                        $total_size += $i;
-                                       if ($total_size > $max_size) { die "Uploaded file too long"; }
+                                       if ($total_size > $max_size) { http_error "413 Request Entity Too Large"; }
                                }
                                $fh->flush();   # Don't close the handle, the file would disappear otherwise
                                next PART;