# Copyright (C) 2015-2020 all contributors # License: AGPL-3.0+ # # Used by -nntpd for listen sockets package PublicInbox::Listener; use strict; use warnings; use base 'PublicInbox::DS'; use Socket qw(SOL_SOCKET SO_KEEPALIVE IPPROTO_TCP TCP_NODELAY); use fields qw(post_accept); use IO::Handle; use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE EPOLLET); 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, 1024); my $self = fields::new($class); $self->SUPER::new($s, EPOLLIN|EPOLLET|EPOLLEXCLUSIVE); $self->{post_accept} = $cb; $self } sub event_step { my ($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 $@; $self->requeue; } elsif ($! == 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;