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| | # Copyright (C) 2015-2021 all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
#
# Used by -nntpd for listen sockets
package PublicInbox::Listener;
use strict;
use parent 'PublicInbox::DS';
use Socket qw(SOL_SOCKET SO_KEEPALIVE IPPROTO_TCP TCP_NODELAY);
use IO::Handle;
use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE);
use Errno qw(EAGAIN ECONNABORTED EPERM);
# Warn on transient errors, mostly resource limitations.
# EINTR would indicate the failure to set NonBlocking in systemd or similar
my %ERR_WARN = map {;
eval("Errno::$_()") => $_
} qw(EMFILE ENFILE ENOBUFS ENOMEM EINTR);
sub new ($$$) {
my ($class, $s, $cb) = @_;
setsockopt($s, SOL_SOCKET, SO_KEEPALIVE, 1);
setsockopt($s, IPPROTO_TCP, TCP_NODELAY, 1); # ignore errors on non-TCP
listen($s, 2**31 - 1); # kernel will clamp
my $self = bless { post_accept => $cb }, $class;
$self->SUPER::new($s, EPOLLIN|EPOLLEXCLUSIVE);
}
sub event_step {
my ($self) = @_;
my $sock = $self->{sock} or return;
# no loop here, we want to fairly distribute clients
# between multiple processes sharing the same socket
# XXX our event loop needs better granularity for
# a single accept() here to be, umm..., acceptable
# on high-traffic sites.
if (my $addr = accept(my $c, $sock)) {
IO::Handle::blocking($c, 0); # no accept4 :<
eval { $self->{post_accept}->($c, $addr, $sock) };
warn "E: $@\n" if $@;
} elsif ($! == EAGAIN || $! == ECONNABORTED || $! == EPERM) {
# EAGAIN is common and likely
# ECONNABORTED is common with bad connections
# EPERM happens if firewall rules prevent a connection
# on Linux (and everything that emulates Linux).
# Firewall rules are sometimes intentional, so we don't
# warn on EPERM to avoid being too noisy...
return;
} elsif (my $sym = $ERR_WARN{int($!)}) {
warn "W: accept(): $! ($sym)\n";
} else {
warn "BUG?: accept(): $!\n";
}
}
1;
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