From 078f637c80cc33c7d29973b95fdc16205ad7bb32 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Wed, 1 Jan 2020 10:38:59 +0000
Subject: wwwstatic: add directory listing + index.html support

It's now possible to use WwwStatic as a standalone PSGI
app to serve static files and recreate the award-winning
web design of https://public-inbox.org/ :>
---
 lib/PublicInbox/WwwStatic.pm | 198 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 194 insertions(+), 4 deletions(-)

(limited to 'lib/PublicInbox/WwwStatic.pm')

diff --git a/lib/PublicInbox/WwwStatic.pm b/lib/PublicInbox/WwwStatic.pm
index ce4bfe9b..bc42236e 100644
--- a/lib/PublicInbox/WwwStatic.pm
+++ b/lib/PublicInbox/WwwStatic.pm
@@ -1,19 +1,48 @@
 # Copyright (C) 2016-2019 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 
+# This package can either be a PSGI response body for a static file
+# OR a standalone PSGI app which returns the above PSGI response body
+# (or an HTML directory listing).
+#
+# It encapsulates the "autoindex", "index", and "gzip_static"
+# functionality of nginx.
 package PublicInbox::WwwStatic;
 use strict;
 use parent qw(Exporter);
+use bytes ();
 use Fcntl qw(SEEK_SET O_RDONLY O_NONBLOCK);
+use POSIX qw(strftime lround);
 use HTTP::Date qw(time2str);
 use HTTP::Status qw(status_message);
 use Errno qw(EACCES ENOTDIR ENOENT);
-our @EXPORT_OK = qw(@NO_CACHE r);
+use URI::Escape qw(uri_escape_utf8);
+use PublicInbox::Hval qw(ascii_html);
+use Plack::MIME;
+our @EXPORT_OK = qw(@NO_CACHE r path_info_raw);
 
 our @NO_CACHE = ('Expires', 'Fri, 01 Jan 1980 00:00:00 GMT',
 		'Pragma', 'no-cache',
 		'Cache-Control', 'no-cache, max-age=0, must-revalidate');
 
+our $STYLE = <<'EOF';
+<style>
+@media screen {
+	*{background:#000;color:#ccc}
+	a{color:#69f;text-decoration:none}
+	a:visited{color:#96f}
+}
+@media screen AND (prefers-color-scheme:light) {
+	*{background:#fff;color:#333}
+	a{color:#00f;text-decoration:none}
+	a:visited{color:#808}
+}
+</style>
+EOF
+
+$STYLE =~ s/^\s*//gm;
+$STYLE =~ tr/\n//d;
+
 sub r ($;$) {
 	my ($code, $msg) = @_;
 	$msg ||= status_message($code);
@@ -69,8 +98,28 @@ sub prepare_range {
 	($code, $len);
 }
 
-sub response {
+# returns a PSGI arrayref response iff .gz and non-.gz mtimes match
+sub try_gzip_static ($$$$) {
 	my ($env, $h, $path, $type) = @_;
+	return unless ($env->{HTTP_ACCEPT_ENCODING} // '') =~ /\bgzip\b/i;
+	my $mtime;
+	return unless -f $path && defined(($mtime = (stat(_))[9]));
+	my $gz = "$path.gz";
+	return unless -f $gz && (stat(_))[9] == $mtime;
+	my $res = response($env, $h, $gz, $type);
+	return if ($res->[0] > 300 || $res->[0] < 200);
+	push @{$res->[1]}, qw(Cache-Control no-transform Content-Encoding gzip);
+	$res;
+}
+
+sub response ($$$;$) {
+	my ($env, $h, $path, $type) = @_;
+	$type //= Plack::MIME->mime_type($path) // 'application/octet-stream';
+	if ($path !~ /\.gz\z/i) {
+		if (my $res = try_gzip_static($env, $h, $path, $type)) {
+			return $res;
+		}
+	}
 
 	my $in;
 	if ($env->{REQUEST_METHOD} eq 'HEAD') {
@@ -108,7 +157,7 @@ sub response {
 	[ $code, $h, $body ];
 }
 
-# called by PSGI servers:
+# called by PSGI servers on each response chunk:
 sub getline {
 	my ($self) = @_;
 	my $len = $self->{len} or return; # undef, tells server we're done
@@ -132,6 +181,147 @@ sub getline {
 	undef;
 }
 
-sub close {} # noop, just let everything go out-of-scope
+sub close {} # noop, called by PSGI server, just let everything go out-of-scope
+
+# OO interface for use as a Plack app
+sub new {
+	my ($class, %opt) = @_;
+	my $index = $opt{'index'} // [ 'index.html' ];
+	$index = [ $index ] if defined($index) && ref($index) ne 'ARRAY';
+	$index = undef if scalar(@$index) == 0;
+	my $style = $opt{style};
+	if (defined $style) {
+		$style = \$style unless ref($style);
+	}
+	my $docroot = $opt{docroot};
+	die "`docroot' not set" unless defined($docroot) && $docroot ne '';
+	bless {
+		docroot => $docroot,
+		index => $index,
+		autoindex => $opt{autoindex},
+		style => $style // \$STYLE,
+	}, $class;
+}
+
+# PATH_INFO is decoded, and we want the undecoded original
+my %path_re_cache;
+sub path_info_raw ($) {
+	my ($env) = @_;
+	my $sn = $env->{SCRIPT_NAME};
+	my $re = $path_re_cache{$sn} ||= do {
+		$sn = '/'.$sn unless index($sn, '/') == 0;
+		$sn =~ s!/\z!!;
+		qr!\A(?:https?://[^/]+)?\Q$sn\E(/[^\?\#]+)!;
+	};
+	$env->{REQUEST_URI} =~ $re ? $1 : $env->{PATH_INFO};
+}
+
+sub redirect_slash ($) {
+	my ($env) = @_;
+	my $url = $env->{'psgi.url_scheme'} . '://';
+	my $host_port = $env->{HTTP_HOST} //
+		"$env->{SERVER_NAME}:$env->{SERVER_PORT}";
+	$url .= $host_port . path_info_raw($env) . '/';
+	my $body = "Redirecting to $url\n";
+	[ 302, [ qw(Content-Type text/plain), 'Location', $url,
+		'Content-Length', length($body) ], [ $body ] ]
+}
+
+sub human_size ($) {
+	my ($size) = @_;
+	my $suffix = '';
+	for my $s (qw(K M G T P)) {
+		last if $size < 1024;
+		$size /= 1024;
+		if ($size <= 1024) {
+			$suffix = $s;
+			last;
+		}
+	}
+	lround($size).$suffix;
+}
+
+# by default, this returns "index.html" if it exists for a given directory
+# It'll generate a directory listing, (autoindex).
+# May be disabled by setting autoindex => 0
+sub dir_response ($$$) {
+	my ($self, $env, $fs_path) = @_;
+	if (my $index = $self->{'index'}) { # serve index.html or similar
+		for my $html (@$index) {
+			my $p = $fs_path . $html;
+			my $res = response($env, [], $p);
+			return $res if $res->[0] != 404;
+		}
+	}
+	return r(404) unless $self->{autoindex};
+	opendir(my $dh, $fs_path) or do {
+		return r(404) if ($! == ENOENT || $! == ENOTDIR);
+		return r(403) if $! == EACCES;
+		return r(500);
+	};
+	my @entries = grep(!/\A\./, readdir($dh));
+	$dh = undef;
+	my (%dirs, %other, %want_gz);
+	my $path_info = $env->{PATH_INFO};
+	push @entries, '..' if $path_info ne '/';
+	for my $base (@entries) {
+		my $href = ascii_html(uri_escape_utf8($base));
+		my $name = ascii_html($base);
+		my @st = stat($fs_path . $base) or next; # unlikely
+		my ($gzipped, $uncompressed, $hsize);
+		my $entry = '';
+		my $mtime = $st[9];
+		if (-d _) {
+			$href .= '/';
+			$name .= '/';
+			$hsize = '-';
+			$dirs{"$base\0$mtime"} = \$entry;
+		} elsif (-f _) {
+			$other{"$base\0$mtime"} = \$entry;
+			if ($base !~ /\.gz\z/i) {
+				$want_gz{"$base.gz\0$mtime"} = undef;
+			}
+			$hsize = human_size($st[7]);
+		} else {
+			next;
+		}
+		# 54 = 80 - (SP length(strftime(%Y-%m-%d %k:%M)) SP human_size)
+		$hsize = sprintf('% 8s', $hsize);
+		my $pad = 54 - length($name);
+		$pad = 1 if $pad <= 0;
+		$entry .= qq(<a\nhref="$href">$name</a>) . (' ' x $pad);
+		$mtime = strftime('%Y-%m-%d %k:%M', gmtime($mtime));
+		$entry .= $mtime . $hsize;
+	}
+
+	# filter out '.gz' files as long as the mtime matches the
+	# uncompressed version
+	delete(@other{keys %want_gz});
+	@entries = ((map { ${$dirs{$_}} } sort keys %dirs),
+			(map { ${$other{$_}} } sort keys %other));
+
+	my $path_info_html = ascii_html($path_info);
+	my $body = "<html><head><title>Index of $path_info_html</title>" .
+		${$self->{style}} .
+		"</head><body><pre>Index of $path_info_html</pre><hr><pre>\n";
+	$body .= join("\n", @entries) . "</pre><hr></body></html>\n";
+	[ 200, [ qw(Content-Type text/html
+			Content-Length), bytes::length($body) ], [ $body ] ]
+}
+
+sub call { # PSGI app endpoint
+	my ($self, $env) = @_;
+	return r(405) if $env->{REQUEST_METHOD} !~ /\A(?:GET|HEAD)\z/;
+	my $path_info = $env->{PATH_INFO};
+	return r(403) if index($path_info, "\0") >= 0;
+	my (@parts) = split(m!/+!, $path_info, -1);
+	return r(403) if grep(/\A(?:\.\.)\z/, @parts) || $parts[0] ne '';
+
+	my $fs_path = join('/', $self->{docroot}, @parts);
+	return dir_response($self, $env, $fs_path) if $parts[-1] eq '';
+
+	my $res = response($env, [], $fs_path);
+	$res->[0] == 404 && -d $fs_path ? redirect_slash($env) : $res;
+}
 
 1;
-- 
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