# Copyright (C) 2016 all contributors
# License: AGPL-3.0+
# when no endpoints match, fallback to this and serve a static file
# or smart HTTP
package PublicInbox::GitHTTPBackend;
use strict;
use warnings;
use Fcntl qw(:seek);
use IO::File;
use PublicInbox::Spawn qw(spawn);
use HTTP::Date qw(time2str);
use HTTP::Status qw(status_message);
# n.b. serving "description" and "cloneurl" should be innocuous enough to
# not cause problems. serving "config" might...
my @text = qw[HEAD info/refs
objects/info/(?:http-alternates|alternates|packs)
cloneurl description];
my @binary = qw!
objects/[a-f0-9]{2}/[a-f0-9]{38}
objects/pack/pack-[a-f0-9]{40}\.(?:pack|idx)
!;
our $ANY = join('|', @binary, @text);
my $BIN = join('|', @binary);
my $TEXT = join('|', @text);
my @no_cache = ('Expires', 'Fri, 01 Jan 1980 00:00:00 GMT',
'Pragma', 'no-cache',
'Cache-Control', 'no-cache, max-age=0, must-revalidate');
my $nextq;
sub do_next () {
my $q = $nextq;
$nextq = undef;
while (my $cb = shift @$q) {
$cb->(); # this may redefine nextq
}
}
sub r ($;$) {
my ($code, $msg) = @_;
$msg ||= status_message($code);
my $len = length($msg);
[ $code, [qw(Content-Type text/plain Content-Length), $len, @no_cache],
[$msg] ]
}
sub serve {
my ($cgi, $git, $path) = @_;
my $service = $cgi->param('service') || '';
if ($service =~ /\Agit-\w+-pack\z/ || $path =~ /\Agit-\w+-pack\z/) {
my $ok = serve_smart($cgi, $git, $path);
return $ok if $ok;
}
serve_dumb($cgi, $git, $path);
}
sub err ($@) {
my ($env, @msg) = @_;
$env->{'psgi.errors'}->print(@msg, "\n");
}
sub drop_client ($) {
if (my $io = $_[0]->{'psgix.io'}) {
$io->close; # this is Danga::Socket::close
}
}
sub serve_dumb {
my ($cgi, $git, $path) = @_;
my @h;
my $type;
if ($path =~ /\A(?:$BIN)\z/o) {
$type = 'application/octet-stream';
push @h, 'Expires', time2str(time + 31536000);
push @h, 'Cache-Control', 'public, max-age=31536000';
} elsif ($path =~ /\A(?:$TEXT)\z/o) {
$type = 'text/plain';
push @h, @no_cache;
} else {
return r(404);
}
my $f = "$git->{git_dir}/$path";
return r(404) unless -f $f && -r _; # just in case it's a FIFO :P
my @st = stat(_);
my $size = $st[7];
my $env = $cgi->{env};
# TODO: If-Modified-Since and Last-Modified?
open my $in, '<', $f or return r(404);
my $len = $size;
my $code = 200;
push @h, 'Content-Type', $type;
if (($env->{HTTP_RANGE} || '') =~ /\bbytes=(\d*)-(\d*)\z/) {
($code, $len) = prepare_range($cgi, $in, \@h, $1, $2, $size);
if ($code == 416) {
push @h, 'Content-Range', "bytes */$size";
return [ 416, \@h, [] ];
}
}
push @h, 'Content-Length', $len;
my $n = 65536;
[ $code, \@h, Plack::Util::inline_object(close => sub { close $in },
getline => sub {
return if $len == 0;
$n = $len if $len < $n;
my $r = sysread($in, my $buf, $n);
if (!defined $r) {
err($env, "$f read error: $!");
} elsif ($r <= 0) {
err($env, "$f EOF with $len bytes left");
} else {
$len -= $r;
$n = 8192;
return $buf;
}
drop_client($env);
return;
})]
}
sub prepare_range {
my ($cgi, $in, $h, $beg, $end, $size) = @_;
my $code = 200;
my $len = $size;
if ($beg eq '') {
if ($end ne '') { # "bytes=-$end" => last N bytes
$beg = $size - $end;
$beg = 0 if $beg < 0;
$end = $size - 1;
$code = 206;
} else {
$code = 416;
}
} else {
if ($beg > $size) {
$code = 416;
} elsif ($end eq '' || $end >= $size) {
$end = $size - 1;
$code = 206;
} elsif ($end < $size) {
$code = 206;
} else {
$code = 416;
}
}
if ($code == 206) {
$len = $end - $beg + 1;
if ($len <= 0) {
$code = 416;
} else {
sysseek($in, $beg, SEEK_SET) or return [ 500, [], [] ];
push @$h, qw(Accept-Ranges bytes Content-Range);
push @$h, "bytes $beg-$end/$size";
# FIXME: Plack::Middleware::Deflater bug?
$cgi->{env}->{'psgix.no-compress'} = 1;
}
}
($code, $len);
}
# returns undef if 403 so it falls back to dumb HTTP
sub serve_smart {
my ($cgi, $git, $path) = @_;
my $env = $cgi->{env};
my $in = $env->{'psgi.input'};
my $fd = eval { fileno($in) };
unless (defined $fd && $fd >= 0) {
$in = input_to_file($env) or return r(500);
}
my ($rpipe, $wpipe);
unless (pipe($rpipe, $wpipe)) {
err($env, "error creating pipe: $! - going static");
return;
}
my %env = %ENV;
# GIT_COMMITTER_NAME, GIT_COMMITTER_EMAIL
# may be set in the server-process and are passed as-is
foreach my $name (qw(QUERY_STRING
REMOTE_USER REMOTE_ADDR
HTTP_CONTENT_ENCODING
CONTENT_TYPE
SERVER_PROTOCOL
REQUEST_METHOD)) {
my $val = $env->{$name};
$env{$name} = $val if defined $val;
}
my $git_dir = $git->{git_dir};
$env{GIT_HTTP_EXPORT_ALL} = '1';
$env{PATH_TRANSLATED} = "$git_dir/$path";
my %rdr = ( 0 => fileno($in), 1 => fileno($wpipe) );
my $pid = spawn([qw(git http-backend)], \%env, \%rdr);
unless (defined $pid) {
err($env, "error spawning: $! - going static");
return;
}
$wpipe = $in = undef;
my $end = sub {
$rpipe = undef;
my $e = $pid == waitpid($pid, 0) ?
$? : "PID:$pid still running?";
if ($e) {
err($env, "git http-backend ($git_dir): $e");
drop_client($env);
}
};
# Danga::Socket users, we queue up the read_enable callback to
# fire after pending writes are complete:
my $buf = '';
if (my $async = $env->{'pi-httpd.async'}) {
my $res;
my $q = sub {
$async->close;
$end->();
$res->(@_);
};
# $async is PublicInbox::HTTPD::Async->new($rpipe, $cb)
$async = $async->($rpipe, sub {
my $r = sysread($rpipe, $buf, 1024, length($buf));
if (!defined $r || $r == 0) {
return $q->(r(500, 'http-backend error'));
}
$r = parse_cgi_headers(\$buf) or return;
if ($r->[0] == 403) {
return $q->(serve_dumb($cgi, $git, $path));
}
my $fh = $res->($r);
$fh->write($buf);
$buf = undef;
my $dst = Plack::Util::inline_object(
write => sub { $fh->write(@_) },
close => sub {
$end->();
$fh->close;
});
$async->async_pass($env->{'psgix.io'}, $dst);
});
sub { ($res) = @_ }; # let Danga::Socket handle the rest.
} else { # getline + close for other PSGI servers
my $r;
do {
$r = read($rpipe, $buf, 1024, length($buf));
if (!defined $r || $r == 0) {
return r(500, 'http-backend error');
}
$r = parse_cgi_headers(\$buf);
} until ($r);
return serve_dumb($cgi, $git, $path) if $r->[0] == 403;
$r->[2] = Plack::Util::inline_object(
close => sub { $end->() },
getline => sub {
my $ret = $buf;
$buf = undef;
defined $ret ? $ret : $rpipe->getline;
});
$r;
}
}
sub input_to_file {
my ($env) = @_;
my $in = IO::File->new_tmpfile;
my $input = $env->{'psgi.input'};
my $buf;
while (1) {
my $r = $input->read($buf, 8192);
unless (defined $r) {
err($env, "error reading input: $!");
return;
}
last if ($r == 0);
$in->write($buf);
}
$in->flush;
$in->sysseek(0, SEEK_SET);
return $in;
}
sub parse_cgi_headers {
my ($bref) = @_;
$$bref =~ s/\A(.*?)\r\n\r\n//s or return;
my $h = $1;
my $code = 200;
my @h;
foreach my $l (split(/\r\n/, $h)) {
my ($k, $v) = split(/:\s*/, $l, 2);
if ($k =~ /\AStatus\z/i) {
($code) = ($v =~ /\b(\d+)\b/);
} else {
push @h, $k, $v;
}
}
[ $code, \@h ]
}
1;