# Copyright (C) 2016-2019 all contributors
# License: AGPL-3.0+
# when no endpoints match, fallback to this and serve a static file
# or smart HTTP. This is our wrapper for git-http-backend(1)
package PublicInbox::GitHTTPBackend;
use strict;
use warnings;
use Fcntl qw(:seek);
use IO::Handle;
use HTTP::Date qw(time2str);
use HTTP::Status qw(status_message);
use Plack::Util;
use PublicInbox::Qspawn;
use PublicInbox::Tmpfile;
# 32 is same as the git-daemon connection limit
my $default_limiter = PublicInbox::Qspawn::Limiter->new(32);
# n.b. serving "description" and "cloneurl" should be innocuous enough to
# not cause problems. serving "config" might...
my @text = qw[HEAD info/refs info/attributes
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, 'git-upload-pack');
my $BIN = join('|', @binary);
my $TEXT = join('|', @text);
my @no_cache = ('Expires', 'Fri, 01 Jan 1980 00:00:00 GMT',
'Pragma', 'no-cache',
'Cache-Control', 'no-cache, max-age=0, must-revalidate');
sub r ($;$) {
my ($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 ($env, $git, $path) = @_;
# XXX compatibility... ugh, can we stop supporting this?
$git = PublicInbox::Git->new($git) unless ref($git);
# Documentation/technical/http-protocol.txt in git.git
# requires one and exactly one query parameter:
if ($env->{QUERY_STRING} =~ /\Aservice=git-[A-Za-z0-9_]+-pack\z/ ||
$path =~ /\Agit-[A-Za-z0-9_]+-pack\z/) {
my $ok = serve_smart($env, $git, $path);
return $ok if $ok;
}
serve_dumb($env, $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 PublicInbox::DS::close
}
}
my $prev = 0;
my $exp;
sub cache_one_year {
my ($h) = @_;
my $t = time + 31536000;
push @$h, 'Expires', $t == $prev ? $exp : ($exp = time2str($prev = $t)),
'Cache-Control', 'public, max-age=31536000';
}
sub static_result ($$$$) {
my ($env, $h, $f, $type) = @_;
return r(404) unless -f $f && -r _; # just in case it's a FIFO :P
# TODO: If-Modified-Since and Last-Modified?
open my $in, '<', $f or return r(404);
my $size = -s $in;
my $len = $size;
my $code = 200;
push @$h, 'Content-Type', $type;
if (($env->{HTTP_RANGE} || '') =~ /\bbytes=([0-9]*)-([0-9]*)\z/) {
($code, $len) = prepare_range($env, $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 serve_dumb {
my ($env, $git, $path) = @_;
my $h = [];
my $type;
if ($path =~ m!\Aobjects/[a-f0-9]{2}/[a-f0-9]{38}\z!) {
$type = 'application/x-git-loose-object';
cache_one_year($h);
} elsif ($path =~ m!\Aobjects/pack/pack-[a-f0-9]{40}\.pack\z!) {
$type = 'application/x-git-packed-objects';
cache_one_year($h);
} elsif ($path =~ m!\Aobjects/pack/pack-[a-f0-9]{40}\.idx\z!) {
$type = 'application/x-git-packed-objects-toc';
cache_one_year($h);
} elsif ($path =~ /\A(?:$TEXT)\z/o) {
$type = 'text/plain';
push @$h, @no_cache;
} else {
return r(404);
}
static_result($env, $h, "$git->{git_dir}/$path", $type);
}
sub prepare_range {
my ($env, $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?
$env->{'psgix.no-compress'} = 1;
}
}
($code, $len);
}
# returns undef if 403 so it falls back to dumb HTTP
sub serve_smart {
my ($env, $git, $path) = @_;
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 $limiter = $git->{-httpbackend_limiter} || $default_limiter;
$env{GIT_HTTP_EXPORT_ALL} = '1';
$env{PATH_TRANSLATED} = "$git->{git_dir}/$path";
my $rdr = input_prepare($env) or return r(500);
my $qsp = PublicInbox::Qspawn->new([qw(git http-backend)], \%env, $rdr);
$qsp->psgi_return($env, $limiter, sub { # parse_hdr
my ($r, $bref) = @_;
my $res = parse_cgi_headers($r, $bref) or return; # incomplete
$res->[0] == 403 ? serve_dumb($env, $git, $path) : $res;
});
}
sub input_prepare {
my ($env) = @_;
my $input = $env->{'psgi.input'};
my $fd = eval { fileno($input) };
if (defined $fd && $fd >= 0) {
return { 0 => $fd };
}
my $id = "git-http.input.$env->{REMOTE_ADDR}:$env->{REMOTE_PORT}";
my $in = tmpfile($id);
unless (defined $in) {
err($env, "could not open temporary file: $!");
return;
}
my $buf;
while (1) {
my $r = $input->read($buf, 8192);
unless (defined $r) {
err($env, "error reading input: $!");
return;
}
last if $r == 0;
unless (print $in $buf) {
err($env, "error writing temporary file: $!");
return;
}
}
# ensure it's visible to git-http-backend(1):
unless ($in->flush) {
err($env, "error writing temporary file: $!");
return;
}
unless (defined(sysseek($in, 0, SEEK_SET))) {
err($env, "error seeking temporary file: $!");
return;
}
{ 0 => fileno($in), -hold => $in };
}
sub parse_cgi_headers {
my ($r, $bref) = @_;
return r(500) unless defined $r && $r >= 0;
$$bref =~ s/\A(.*?)\r?\n\r?\n//s or return $r == 0 ? r(500) : undef;
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([0-9]+)\b/);
} else {
push @h, $k, $v;
}
}
[ $code, \@h ]
}
1;