# Copyright (C) 2016-2018 all contributors
# License: AGPL-3.0+
#
# Generic PSGI server for convenience. It aims to provide
# a consistent experience for public-inbox admins so they don't have
# to learn different ways to admin both NNTP and HTTP components.
# There's nothing which depends on public-inbox, here.
# Each instance of this class represents a HTTP client socket
package PublicInbox::HTTP;
use strict;
use warnings;
use base qw(PublicInbox::DS);
use fields qw(httpd env input_left remote_addr remote_port forward pull);
use bytes (); # only for bytes::length
use Fcntl qw(:seek);
use Plack::HTTPParser qw(parse_http_request); # XS or pure Perl
use HTTP::Status qw(status_message);
use HTTP::Date qw(time2str);
use IO::Handle;
require PublicInbox::EvCleanup;
PublicInbox::DS->import(qw(msg_more));
use PublicInbox::Syscall qw(EPOLLIN EPOLLONESHOT);
use constant {
CHUNK_START => -1, # [a-f0-9]+\r\n
CHUNK_END => -2, # \r\n
CHUNK_ZEND => -3, # \r\n
CHUNK_MAX_HDR => 256,
};
use Errno qw(EAGAIN);
my $pipelineq = [];
my $pipet;
sub process_pipelineq () {
my $q = $pipelineq;
$pipet = undef;
$pipelineq = [];
foreach (@$q) {
next unless $_->{sock};
rbuf_process($_);
}
}
# Use the same configuration parameter as git since this is primarily
# a slow-client sponge for git-http-backend
# TODO: support per-respository http.maxRequestBuffer somehow...
our $MAX_REQUEST_BUFFER = $ENV{GIT_HTTP_MAX_REQUEST_BUFFER} ||
(10 * 1024 * 1024);
open(my $null_io, '<', '/dev/null') or die "failed to open /dev/null: $!";
my $http_date;
my $prev = 0;
sub http_date () {
my $now = time;
$now == $prev ? $http_date : ($http_date = time2str($prev = $now));
}
sub new ($$$) {
my ($class, $sock, $addr, $httpd) = @_;
my $self = fields::new($class);
$self->SUPER::new($sock, EPOLLIN | EPOLLONESHOT);
$self->{httpd} = $httpd;
($self->{remote_addr}, $self->{remote_port}) =
PublicInbox::Daemon::host_with_port($addr);
$self;
}
sub event_step { # called by PublicInbox::DS
my ($self) = @_;
return unless $self->flush_write && $self->{sock};
# only read more requests if we've drained the write buffer,
# otherwise we can be buffering infinitely w/o backpressure
return read_input($self) if defined $self->{env};
my $rbuf = $self->{rbuf} // (\(my $x = ''));
$self->do_read($rbuf, 8192, bytes::length($$rbuf)) or return;
rbuf_process($self, $rbuf);
}
sub rbuf_process {
my ($self, $rbuf) = @_;
$rbuf //= $self->{rbuf} // (\(my $x = ''));
my %env = %{$self->{httpd}->{env}}; # full hash copy
my $r = parse_http_request($$rbuf, \%env);
# We do not support Trailers in chunked requests, for now
# (they are rarely-used and git (as of 2.7.2) does not use them)
if ($r == -1 || $env{HTTP_TRAILER} ||
# this length-check is necessary for PURE_PERL=1:
($r == -2 && bytes::length($$rbuf) > 0x4000)) {
return quit($self, 400);
}
if ($r < 0) { # incomplete
$self->rbuf_idle($rbuf);
return $self->requeue;
}
$$rbuf = substr($$rbuf, $r);
my $len = input_prepare($self, \%env);
defined $len or return write_err($self, undef); # EMFILE/ENFILE
$len ? read_input($self, $rbuf) : app_dispatch($self, undef, $rbuf);
}
# IO::Handle::write returns boolean, this returns bytes written:
sub xwrite ($$$) {
my ($fh, $rbuf, $max) = @_;
my $w = bytes::length($$rbuf);
$w = $max if $w > $max;
$fh->write($$rbuf, $w) or return;
$w;
}
sub read_input ($;$) {
my ($self, $rbuf) = @_;
$rbuf //= $self->{rbuf} // (\(my $x = ''));
my $env = $self->{env};
return if $env->{REMOTE_ADDR}; # in app dispatch
return read_input_chunked($self, $rbuf) if env_chunked($env);
# env->{CONTENT_LENGTH} (identity)
my $len = delete $self->{input_left};
my $input = $env->{'psgi.input'};
while ($len > 0) {
if ($$rbuf ne '') {
my $w = xwrite($input, $rbuf, $len);
return write_err($self, $len) unless $w;
$len -= $w;
die "BUG: $len < 0 (w=$w)" if $len < 0;
if ($len == 0) { # next request may be pipelined
$$rbuf = substr($$rbuf, $w);
last;
}
$$rbuf = '';
}
$self->do_read($rbuf, 8192) or return recv_err($self, $len);
# continue looping if $r > 0;
}
app_dispatch($self, $input, $rbuf);
}
sub app_dispatch {
my ($self, $input, $rbuf) = @_;
$self->rbuf_idle($rbuf);
my $env = $self->{env};
$env->{REMOTE_ADDR} = $self->{remote_addr};
$env->{REMOTE_PORT} = $self->{remote_port};
if (my $host = $env->{HTTP_HOST}) {
$host =~ s/:([0-9]+)\z// and $env->{SERVER_PORT} = $1;
$env->{SERVER_NAME} = $host;
}
if (defined $input) {
sysseek($input, 0, SEEK_SET) or
die "BUG: psgi.input seek failed: $!";
}
# note: NOT $self->{sock}, we want our close (+ PublicInbox::DS::close),
# to do proper cleanup:
$env->{'psgix.io'} = $self; # only for ->close
my $res = Plack::Util::run_app($self->{httpd}->{app}, $env);
eval {
if (ref($res) eq 'CODE') {
$res->(sub { response_write($self, $env, $_[0]) });
} else {
response_write($self, $env, $res);
}
};
$self->close if $@;
}
sub response_header_write {
my ($self, $env, $res) = @_;
my $proto = $env->{SERVER_PROTOCOL} or return; # HTTP/0.9 :P
my $status = $res->[0];
my $h = "$proto $status " . status_message($status) . "\r\n";
my ($len, $chunked);
my $headers = $res->[1];
for (my $i = 0; $i < @$headers; $i += 2) {
my $k = $headers->[$i];
my $v = $headers->[$i + 1];
next if $k =~ /\A(?:Connection|Date)\z/i;
$len = $v if $k =~ /\AContent-Length\z/i;
if ($k =~ /\ATransfer-Encoding\z/i && $v =~ /\bchunked\b/i) {
$chunked = 1;
}
$h .= "$k: $v\r\n";
}
my $conn = $env->{HTTP_CONNECTION} || '';
my $term = defined($len) || $chunked;
my $prot_persist = ($proto eq 'HTTP/1.1') && ($conn !~ /\bclose\b/i);
my $alive;
if (!$term && $prot_persist) { # auto-chunk
$chunked = $alive = 2;
$h .= "Transfer-Encoding: chunked\r\n";
# no need for "Connection: keep-alive" with HTTP/1.1
} elsif ($term && ($prot_persist || ($conn =~ /\bkeep-alive\b/i))) {
$alive = 1;
$h .= "Connection: keep-alive\r\n";
} else {
$alive = 0;
$h .= "Connection: close\r\n";
}
$h .= 'Date: ' . http_date() . "\r\n\r\n";
if (($len || $chunked) && $env->{REQUEST_METHOD} ne 'HEAD') {
msg_more($self, $h);
} else {
$self->write(\$h);
}
$alive;
}
# middlewares such as Deflater may write empty strings
sub chunked_wcb ($) {
my ($self) = @_;
sub {
return if $_[0] eq '';
msg_more($self, sprintf("%x\r\n", bytes::length($_[0])));
msg_more($self, $_[0]);
# use $self->write(\"\n\n") if you care about real-time
# streaming responses, public-inbox WWW does not.
msg_more($self, "\r\n");
}
}
sub identity_wcb ($) {
my ($self) = @_;
sub { $self->write(\($_[0])) if $_[0] ne '' }
}
sub next_request ($) {
my ($self) = @_;
if ($self->{rbuf}) {
# avoid recursion for pipelined requests
push @$pipelineq, $self;
$pipet ||= PublicInbox::EvCleanup::asap(*process_pipelineq);
} else { # wait for next request
$self->requeue;
}
}
sub response_done_cb ($$) {
my ($self, $alive) = @_;
sub {
my $env = delete $self->{env};
$self->write(\"0\r\n\r\n") if $alive == 2;
$self->write($alive ? \&next_request : \&close);
}
}
sub getline_cb ($$$) {
my ($self, $write, $close) = @_;
local $/ = \8192;
my $forward = $self->{forward};
# limit our own running time for fairness with other
# clients and to avoid buffering too much:
if ($forward) {
my $buf = eval { $forward->getline };
if (defined $buf) {
$write->($buf); # may close in PublicInbox::DS::write
if ($self->{sock}) {
my $next = $self->{pull};
if ($self->{wbuf}) {
$self->write($next);
} else {
PublicInbox::EvCleanup::asap($next);
}
return;
}
} elsif ($@) {
err($self, "response ->getline error: $@");
$forward = undef;
$self->close;
}
}
delete @$self{qw(forward pull)};
# avoid recursion
if ($forward) {
eval { $forward->close };
if ($@) {
err($self, "response ->close error: $@");
$self->close; # idempotent
}
}
$close->();
}
sub getline_response ($$$) {
my ($self, $write, $close) = @_;
my $pull = $self->{pull} = sub { getline_cb($self, $write, $close) };
$pull->();
}
sub response_write {
my ($self, $env, $res) = @_;
my $alive = response_header_write($self, $env, $res);
my $close = response_done_cb($self, $alive);
my $write = $alive == 2 ? chunked_wcb($self) : identity_wcb($self);
if (defined(my $body = $res->[2])) {
if (ref $body eq 'ARRAY') {
$write->($_) foreach @$body;
$close->();
} else {
$self->{forward} = $body;
getline_response($self, $write, $close);
}
} else {
# this is returned to the calling application:
Plack::Util::inline_object(write => $write, close => $close);
}
}
sub input_tmpfile ($) {
open($_[0], '+>', undef);
$_[0]->autoflush(1);
}
sub input_prepare {
my ($self, $env) = @_;
my $input;
my $len = $env->{CONTENT_LENGTH};
if ($len) {
if ($len > $MAX_REQUEST_BUFFER) {
quit($self, 413);
return;
}
input_tmpfile($input);
} elsif (env_chunked($env)) {
$len = CHUNK_START;
input_tmpfile($input);
} else {
$input = $null_io;
}
# TODO: expire idle clients on ENFILE / EMFILE
return unless $input;
$env->{'psgi.input'} = $input;
$self->{env} = $env;
$self->{input_left} = $len || 0;
}
sub env_chunked { ($_[0]->{HTTP_TRANSFER_ENCODING} || '') =~ /\bchunked\b/i }
sub err ($$) {
eval { $_[0]->{httpd}->{env}->{'psgi.errors'}->print($_[1]."\n") };
}
sub write_err {
my ($self, $len) = @_;
my $msg = $! || '(zero write)';
$msg .= " ($len bytes remaining)" if defined $len;
err($self, "error buffering to input: $msg");
quit($self, 500);
}
sub recv_err {
my ($self, $len) = @_;
if ($! == EAGAIN) { # epoll/kevent watch already set by do_read
$self->{input_left} = $len;
} else {
err($self, "error reading input: $! ($len bytes remaining)");
}
}
sub read_input_chunked { # unlikely...
my ($self, $rbuf) = @_;
$rbuf //= $self->{rbuf} // (\(my $x = ''));
my $input = $self->{env}->{'psgi.input'};
my $len = delete $self->{input_left};
while (1) { # chunk start
if ($len == CHUNK_ZEND) {
$$rbuf =~ s/\A\r\n//s and
return app_dispatch($self, $input, $rbuf);
return quit($self, 400) if bytes::length($$rbuf) > 2;
}
if ($len == CHUNK_END) {
if ($$rbuf =~ s/\A\r\n//s) {
$len = CHUNK_START;
} elsif (bytes::length($$rbuf) > 2) {
return quit($self, 400);
}
}
if ($len == CHUNK_START) {
if ($$rbuf =~ s/\A([a-f0-9]+).*?\r\n//i) {
$len = hex $1;
if (($len + -s $input) > $MAX_REQUEST_BUFFER) {
return quit($self, 413);
}
} elsif (bytes::length($$rbuf) > CHUNK_MAX_HDR) {
return quit($self, 400);
}
# will break from loop since $len >= 0
}
if ($len < 0) { # chunk header is trickled, read more
$self->do_read($rbuf, 8192, bytes::length($$rbuf)) or
return recv_err($self, $len);
# (implicit) goto chunk_start if $r > 0;
}
$len = CHUNK_ZEND if $len == 0;
# drain the current chunk
until ($len <= 0) {
if ($$rbuf ne '') {
my $w = xwrite($input, $rbuf, $len);
return write_err($self, "$len chunk") if !$w;
$len -= $w;
if ($len == 0) {
# we may have leftover data to parse
# in chunk
$$rbuf = substr($$rbuf, $w);
$len = CHUNK_END;
} elsif ($len < 0) {
die "BUG: len < 0: $len";
} else {
$$rbuf = '';
}
}
if ($$rbuf eq '') {
# read more of current chunk
$self->do_read($rbuf, 8192) or
return recv_err($self, $len);
}
}
}
}
sub quit {
my ($self, $status) = @_;
my $h = "HTTP/1.1 $status " . status_message($status) . "\r\n\r\n";
$self->write(\$h);
$self->close;
}
sub close {
my $self = $_[0];
if (my $env = delete $self->{env}) {
delete $env->{'psgix.io'}; # prevent circular references
}
delete $self->{pull};
if (my $forward = delete $self->{forward}) {
eval { $forward->close };
err($self, "forward ->close error: $@") if $@;
}
$self->SUPER::close; # PublicInbox::DS::close
}
# for graceful shutdown in PublicInbox::Daemon:
sub busy () {
my ($self) = @_;
($self->{rbuf} || $self->{env} || $self->{wbuf});
}
# fires after pending writes are complete:
sub restart_pass ($) {
$_[0]->{forward}->restart_read; # see PublicInbox::HTTPD::Async
}
sub enqueue_restart_pass ($) { $_[0]->write(\&restart_pass) }
1;