Adding upstream version 1:9.16.44.upstream/1%9.16.44

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 5521 insertions, 0 deletions

diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
new file mode 100644
index 0000000..d6578ea
--- /dev/null
+++ b/lib/isc/unix/socket.c
@@ -0,0 +1,5521 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \file */
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#if defined(HAVE_SYS_SYSCTL_H) && !defined(__linux__)
+#include <sys/sysctl.h>
+#endif /* if defined(HAVE_SYS_SYSCTL_H) && !defined(__linux__) */
+#include <sys/time.h>
+#include <sys/uio.h>
+
+#if defined(HAVE_LINUX_NETLINK_H) && defined(HAVE_LINUX_RTNETLINK_H)
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#endif /* if defined(HAVE_LINUX_NETLINK_H) && defined(HAVE_LINUX_RTNETLINK_H) \
+	*/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <isc/app.h>
+#include <isc/buffer.h>
+#include <isc/condition.h>
+#include <isc/formatcheck.h>
+#include <isc/list.h>
+#include <isc/log.h>
+#include <isc/mem.h>
+#include <isc/mutex.h>
+#include <isc/net.h>
+#include <isc/once.h>
+#include <isc/platform.h>
+#include <isc/print.h>
+#include <isc/refcount.h>
+#include <isc/region.h>
+#include <isc/resource.h>
+#include <isc/socket.h>
+#include <isc/stats.h>
+#include <isc/strerr.h>
+#include <isc/string.h>
+#include <isc/task.h>
+#include <isc/thread.h>
+#include <isc/util.h>
+
+#ifdef ISC_PLATFORM_HAVESYSUNH
+#include <sys/un.h>
+#endif /* ifdef ISC_PLATFORM_HAVESYSUNH */
+#ifdef HAVE_KQUEUE
+#include <sys/event.h>
+#endif /* ifdef HAVE_KQUEUE */
+#ifdef HAVE_EPOLL_CREATE1
+#include <sys/epoll.h>
+#endif /* ifdef HAVE_EPOLL_CREATE1 */
+#if defined(HAVE_SYS_DEVPOLL_H)
+#include <sys/devpoll.h>
+#elif defined(HAVE_DEVPOLL_H)
+#include <devpoll.h>
+#endif /* if defined(HAVE_SYS_DEVPOLL_H) */
+
+#include <netinet/tcp.h>
+
+#include "errno2result.h"
+
+#ifdef ENABLE_TCP_FASTOPEN
+#include <netinet/tcp.h>
+#endif /* ifdef ENABLE_TCP_FASTOPEN */
+
+#ifdef HAVE_JSON_C
+#include <json_object.h>
+#endif /* HAVE_JSON_C */
+
+#ifdef HAVE_LIBXML2
+#include <libxml/xmlwriter.h>
+#define ISC_XMLCHAR (const xmlChar *)
+#endif /* HAVE_LIBXML2 */
+
+/*%
+ * Choose the most preferable multiplex method.
+ */
+#if defined(HAVE_KQUEUE)
+#define USE_KQUEUE
+#elif defined(HAVE_EPOLL_CREATE1)
+#define USE_EPOLL
+#elif defined(HAVE_SYS_DEVPOLL_H) || defined(HAVE_DEVPOLL_H)
+#define USE_DEVPOLL
+typedef struct {
+	unsigned int want_read : 1, want_write : 1;
+} pollinfo_t;
+#else /* if defined(HAVE_KQUEUE) */
+#define USE_SELECT
+#endif /* HAVE_KQUEUE */
+
+/*
+ * Set by the -T dscp option on the command line. If set to a value
+ * other than -1, we check to make sure DSCP values match it, and
+ * assert if not.
+ */
+int isc_dscp_check_value = -1;
+
+/*%
+ * Maximum number of allowable open sockets.  This is also the maximum
+ * allowable socket file descriptor.
+ *
+ * Care should be taken before modifying this value for select():
+ * The API standard doesn't ensure select() accept more than (the system default
+ * of) FD_SETSIZE descriptors, and the default size should in fact be fine in
+ * the vast majority of cases.  This constant should therefore be increased only
+ * when absolutely necessary and possible, i.e., the server is exhausting all
+ * available file descriptors (up to FD_SETSIZE) and the select() function
+ * and FD_xxx macros support larger values than FD_SETSIZE (which may not
+ * always by true, but we keep using some of them to ensure as much
+ * portability as possible).  Note also that overall server performance
+ * may be rather worsened with a larger value of this constant due to
+ * inherent scalability problems of select().
+ *
+ * As a special note, this value shouldn't have to be touched if
+ * this is a build for an authoritative only DNS server.
+ */
+#ifndef ISC_SOCKET_MAXSOCKETS
+#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
+#ifdef TUNE_LARGE
+#define ISC_SOCKET_MAXSOCKETS 21000
+#else /* ifdef TUNE_LARGE */
+#define ISC_SOCKET_MAXSOCKETS 4096
+#endif /* TUNE_LARGE */
+#elif defined(USE_SELECT)
+#define ISC_SOCKET_MAXSOCKETS FD_SETSIZE
+#endif /* USE_KQUEUE... */
+#endif /* ISC_SOCKET_MAXSOCKETS */
+
+#ifdef USE_SELECT
+/*%
+ * Mac OS X needs a special definition to support larger values in select().
+ * We always define this because a larger value can be specified run-time.
+ */
+#ifdef __APPLE__
+#define _DARWIN_UNLIMITED_SELECT
+#endif /* __APPLE__ */
+#endif /* USE_SELECT */
+
+#ifdef ISC_SOCKET_USE_POLLWATCH
+/*%
+ * If this macro is defined, enable workaround for a Solaris /dev/poll kernel
+ * bug: DP_POLL ioctl could keep sleeping even if socket I/O is possible for
+ * some of the specified FD.  The idea is based on the observation that it's
+ * likely for a busy server to keep receiving packets.  It specifically works
+ * as follows: the socket watcher is first initialized with the state of
+ * "poll_idle".  While it's in the idle state it keeps sleeping until a socket
+ * event occurs.  When it wakes up for a socket I/O event, it moves to the
+ * poll_active state, and sets the poll timeout to a short period
+ * (ISC_SOCKET_POLLWATCH_TIMEOUT msec).  If timeout occurs in this state, the
+ * watcher goes to the poll_checking state with the same timeout period.
+ * In this state, the watcher tries to detect whether this is a break
+ * during intermittent events or the kernel bug is triggered.  If the next
+ * polling reports an event within the short period, the previous timeout is
+ * likely to be a kernel bug, and so the watcher goes back to the active state.
+ * Otherwise, it moves to the idle state again.
+ *
+ * It's not clear whether this is a thread-related bug, but since we've only
+ * seen this with threads, this workaround is used only when enabling threads.
+ */
+
+typedef enum { poll_idle, poll_active, poll_checking } pollstate_t;
+
+#ifndef ISC_SOCKET_POLLWATCH_TIMEOUT
+#define ISC_SOCKET_POLLWATCH_TIMEOUT 10
+#endif /* ISC_SOCKET_POLLWATCH_TIMEOUT */
+#endif /* ISC_SOCKET_USE_POLLWATCH */
+
+/*%
+ * Per-FD lock buckets, we shuffle them around a bit as FDs come in herds.
+ */
+#define FDLOCK_BITS  10
+#define FDLOCK_COUNT (1 << FDLOCK_BITS)
+#define FDLOCK_ID(fd)                                   \
+	(((fd) % (FDLOCK_COUNT) >> (FDLOCK_BITS / 2)) | \
+	 (((fd) << (FDLOCK_BITS / 2)) % (FDLOCK_COUNT)))
+
+/*%
+ * Maximum number of events communicated with the kernel.  There should normally
+ * be no need for having a large number.
+ */
+#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
+#ifndef ISC_SOCKET_MAXEVENTS
+#ifdef TUNE_LARGE
+#define ISC_SOCKET_MAXEVENTS 2048
+#else /* ifdef TUNE_LARGE */
+#define ISC_SOCKET_MAXEVENTS 64
+#endif /* TUNE_LARGE */
+#endif /* ifndef ISC_SOCKET_MAXEVENTS */
+#endif /* if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL) \
+	* */
+
+/*%
+ * Some systems define the socket length argument as an int, some as size_t,
+ * some as socklen_t.  This is here so it can be easily changed if needed.
+ */
+#ifndef socklen_t
+#define socklen_t unsigned int
+#endif /* ifndef socklen_t */
+
+/*%
+ * Define what the possible "soft" errors can be.  These are non-fatal returns
+ * of various network related functions, like recv() and so on.
+ *
+ * For some reason, BSDI (and perhaps others) will sometimes return <0
+ * from recv() but will have errno==0.  This is broken, but we have to
+ * work around it here.
+ */
+#define SOFT_ERROR(e)                                             \
+	((e) == EAGAIN || (e) == EWOULDBLOCK || (e) == ENOBUFS || \
+	 (e) == EINTR || (e) == 0)
+
+#define DLVL(x) ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(x)
+
+/*!<
+ * DLVL(90)  --  Function entry/exit and other tracing.
+ * DLVL(70)  --  Socket "correctness" -- including returning of events, etc.
+ * DLVL(60)  --  Socket data send/receive
+ * DLVL(50)  --  Event tracing, including receiving/sending completion events.
+ * DLVL(20)  --  Socket creation/destruction.
+ */
+#define TRACE_LEVEL	  90
+#define CORRECTNESS_LEVEL 70
+#define IOEVENT_LEVEL	  60
+#define EVENT_LEVEL	  50
+#define CREATION_LEVEL	  20
+
+#define TRACE	    DLVL(TRACE_LEVEL)
+#define CORRECTNESS DLVL(CORRECTNESS_LEVEL)
+#define IOEVENT	    DLVL(IOEVENT_LEVEL)
+#define EVENT	    DLVL(EVENT_LEVEL)
+#define CREATION    DLVL(CREATION_LEVEL)
+
+typedef isc_event_t intev_t;
+
+#define SOCKET_MAGIC	ISC_MAGIC('I', 'O', 'i', 'o')
+#define VALID_SOCKET(s) ISC_MAGIC_VALID(s, SOCKET_MAGIC)
+
+/*!
+ * IPv6 control information.  If the socket is an IPv6 socket we want
+ * to collect the destination address and interface so the client can
+ * set them on outgoing packets.
+ */
+#ifndef USE_CMSG
+#define USE_CMSG 1
+#endif /* ifndef USE_CMSG */
+
+/*%
+ * NetBSD and FreeBSD can timestamp packets.  XXXMLG Should we have
+ * a setsockopt() like interface to request timestamps, and if the OS
+ * doesn't do it for us, call gettimeofday() on every UDP receive?
+ */
+#ifdef SO_TIMESTAMP
+#ifndef USE_CMSG
+#define USE_CMSG 1
+#endif /* ifndef USE_CMSG */
+#endif /* ifdef SO_TIMESTAMP */
+
+#if defined(SO_RCVBUF) && defined(ISC_RECV_BUFFER_SIZE)
+#define SET_RCVBUF
+#endif
+
+#if defined(SO_SNDBUF) && defined(ISC_SEND_BUFFER_SIZE)
+#define SET_SNDBUF
+#endif
+
+/*%
+ * Instead of calculating the cmsgbuf lengths every time we take
+ * a rule of thumb approach - sizes are taken from x86_64 linux,
+ * multiplied by 2, everything should fit. Those sizes are not
+ * large enough to cause any concern.
+ */
+#if defined(USE_CMSG)
+#define CMSG_SP_IN6PKT 40
+#else /* if defined(USE_CMSG) */
+#define CMSG_SP_IN6PKT 0
+#endif /* if defined(USE_CMSG) */
+
+#if defined(USE_CMSG) && defined(SO_TIMESTAMP)
+#define CMSG_SP_TIMESTAMP 32
+#else /* if defined(USE_CMSG) && defined(SO_TIMESTAMP) */
+#define CMSG_SP_TIMESTAMP 0
+#endif /* if defined(USE_CMSG) && defined(SO_TIMESTAMP) */
+
+#if defined(USE_CMSG) && (defined(IPV6_TCLASS) || defined(IP_TOS))
+#define CMSG_SP_TCTOS 24
+#else /* if defined(USE_CMSG) && (defined(IPV6_TCLASS) || defined(IP_TOS)) */
+#define CMSG_SP_TCTOS 0
+#endif /* if defined(USE_CMSG) && (defined(IPV6_TCLASS) || defined(IP_TOS)) */
+
+#define CMSG_SP_INT 24
+
+/* Align cmsg buffers to be safe on SPARC etc. */
+#define RECVCMSGBUFLEN                                                       \
+	ISC_ALIGN(2 * (CMSG_SP_IN6PKT + CMSG_SP_TIMESTAMP + CMSG_SP_TCTOS) + \
+			  1,                                                 \
+		  sizeof(void *))
+#define SENDCMSGBUFLEN                                                    \
+	ISC_ALIGN(2 * (CMSG_SP_IN6PKT + CMSG_SP_INT + CMSG_SP_TCTOS) + 1, \
+		  sizeof(void *))
+
+/*%
+ * The number of times a send operation is repeated if the result is EINTR.
+ */
+#define NRETRIES 10
+
+typedef struct isc__socketthread isc__socketthread_t;
+
+#define NEWCONNSOCK(ev) ((ev)->newsocket)
+
+struct isc_socket {
+	/* Not locked. */
+	unsigned int magic;
+	isc_socketmgr_t *manager;
+	isc_mutex_t lock;
+	isc_sockettype_t type;
+	const isc_statscounter_t *statsindex;
+	isc_refcount_t references;
+
+	/* Locked by socket lock. */
+	ISC_LINK(isc_socket_t) link;
+	int fd;
+	int pf;
+	int threadid;
+	char name[16];
+	void *tag;
+
+	ISC_LIST(isc_socketevent_t) send_list;
+	ISC_LIST(isc_socketevent_t) recv_list;
+	ISC_LIST(isc_socket_newconnev_t) accept_list;
+	ISC_LIST(isc_socket_connev_t) connect_list;
+
+	isc_sockaddr_t peer_address; /* remote address */
+
+	unsigned int listener : 1,	       /* listener socket */
+		connected : 1, connecting : 1, /* connect pending
+						* */
+		bound  : 1,		       /* bound to local addr */
+		dupped : 1, active : 1,	       /* currently active */
+		pktdscp : 1;		       /* per packet dscp */
+
+#ifdef ISC_PLATFORM_RECVOVERFLOW
+	unsigned char overflow; /* used for MSG_TRUNC fake */
+#endif				/* ifdef ISC_PLATFORM_RECVOVERFLOW */
+
+	unsigned int dscp;
+};
+
+#define SOCKET_MANAGER_MAGIC ISC_MAGIC('I', 'O', 'm', 'g')
+#define VALID_MANAGER(m)     ISC_MAGIC_VALID(m, SOCKET_MANAGER_MAGIC)
+
+struct isc_socketmgr {
+	/* Not locked. */
+	unsigned int magic;
+	isc_mem_t *mctx;
+	isc_mutex_t lock;
+	isc_stats_t *stats;
+	int nthreads;
+	isc__socketthread_t *threads;
+	unsigned int maxsocks;
+	/* Locked by manager lock. */
+	ISC_LIST(isc_socket_t) socklist;
+	int reserved; /* unlocked */
+	isc_condition_t shutdown_ok;
+	size_t maxudp;
+};
+
+struct isc__socketthread {
+	isc_socketmgr_t *manager;
+	int threadid;
+	isc_thread_t thread;
+	int pipe_fds[2];
+	isc_mutex_t *fdlock;
+	/* Locked by fdlock. */
+	isc_socket_t **fds;
+	int *fdstate;
+#ifdef USE_KQUEUE
+	int kqueue_fd;
+	int nevents;
+	struct kevent *events;
+#endif /* USE_KQUEUE */
+#ifdef USE_EPOLL
+	int epoll_fd;
+	int nevents;
+	struct epoll_event *events;
+	uint32_t *epoll_events;
+#endif /* USE_EPOLL */
+#ifdef USE_DEVPOLL
+	int devpoll_fd;
+	isc_resourcevalue_t open_max;
+	unsigned int calls;
+	int nevents;
+	struct pollfd *events;
+	pollinfo_t *fdpollinfo;
+#endif /* USE_DEVPOLL */
+#ifdef USE_SELECT
+	int fd_bufsize;
+	fd_set *read_fds;
+	fd_set *read_fds_copy;
+	fd_set *write_fds;
+	fd_set *write_fds_copy;
+	int maxfd;
+#endif /* USE_SELECT */
+};
+
+#define CLOSED	      0 /* this one must be zero */
+#define MANAGED	      1
+#define CLOSE_PENDING 2
+
+/*
+ * send() and recv() iovec counts
+ */
+#define MAXSCATTERGATHER_SEND (ISC_SOCKET_MAXSCATTERGATHER)
+#ifdef ISC_PLATFORM_RECVOVERFLOW
+#define MAXSCATTERGATHER_RECV (ISC_SOCKET_MAXSCATTERGATHER + 1)
+#else /* ifdef ISC_PLATFORM_RECVOVERFLOW */
+#define MAXSCATTERGATHER_RECV (ISC_SOCKET_MAXSCATTERGATHER)
+#endif /* ifdef ISC_PLATFORM_RECVOVERFLOW */
+
+static isc_result_t
+socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
+	      isc_socket_t **socketp, isc_socket_t *dup_socket);
+static void
+send_recvdone_event(isc_socket_t *, isc_socketevent_t **);
+static void
+send_senddone_event(isc_socket_t *, isc_socketevent_t **);
+static void
+send_connectdone_event(isc_socket_t *, isc_socket_connev_t **);
+static void
+free_socket(isc_socket_t **);
+static isc_result_t
+allocate_socket(isc_socketmgr_t *, isc_sockettype_t, isc_socket_t **);
+static void
+destroy(isc_socket_t **);
+static void
+internal_accept(isc_socket_t *);
+static void
+internal_connect(isc_socket_t *);
+static void
+internal_recv(isc_socket_t *);
+static void
+internal_send(isc_socket_t *);
+static void
+process_cmsg(isc_socket_t *, struct msghdr *, isc_socketevent_t *);
+static void
+build_msghdr_send(isc_socket_t *, char *, isc_socketevent_t *, struct msghdr *,
+		  struct iovec *, size_t *);
+static void
+build_msghdr_recv(isc_socket_t *, char *, isc_socketevent_t *, struct msghdr *,
+		  struct iovec *, size_t *);
+static bool
+process_ctlfd(isc__socketthread_t *thread);
+static void
+setdscp(isc_socket_t *sock, isc_dscp_t dscp);
+
+#define SELECT_POKE_SHUTDOWN (-1)
+#define SELECT_POKE_NOTHING  (-2)
+#define SELECT_POKE_READ     (-3)
+#define SELECT_POKE_ACCEPT   (-3) /*%< Same as _READ */
+#define SELECT_POKE_WRITE    (-4)
+#define SELECT_POKE_CONNECT  (-4) /*%< Same as _WRITE */
+#define SELECT_POKE_CLOSE    (-5)
+
+/*%
+ * Shortcut index arrays to get access to statistics counters.
+ */
+enum {
+	STATID_OPEN = 0,
+	STATID_OPENFAIL = 1,
+	STATID_CLOSE = 2,
+	STATID_BINDFAIL = 3,
+	STATID_CONNECTFAIL = 4,
+	STATID_CONNECT = 5,
+	STATID_ACCEPTFAIL = 6,
+	STATID_ACCEPT = 7,
+	STATID_SENDFAIL = 8,
+	STATID_RECVFAIL = 9,
+	STATID_ACTIVE = 10
+};
+static const isc_statscounter_t udp4statsindex[] = {
+	isc_sockstatscounter_udp4open,
+	isc_sockstatscounter_udp4openfail,
+	isc_sockstatscounter_udp4close,
+	isc_sockstatscounter_udp4bindfail,
+	isc_sockstatscounter_udp4connectfail,
+	isc_sockstatscounter_udp4connect,
+	-1,
+	-1,
+	isc_sockstatscounter_udp4sendfail,
+	isc_sockstatscounter_udp4recvfail,
+	isc_sockstatscounter_udp4active
+};
+static const isc_statscounter_t udp6statsindex[] = {
+	isc_sockstatscounter_udp6open,
+	isc_sockstatscounter_udp6openfail,
+	isc_sockstatscounter_udp6close,
+	isc_sockstatscounter_udp6bindfail,
+	isc_sockstatscounter_udp6connectfail,
+	isc_sockstatscounter_udp6connect,
+	-1,
+	-1,
+	isc_sockstatscounter_udp6sendfail,
+	isc_sockstatscounter_udp6recvfail,
+	isc_sockstatscounter_udp6active
+};
+static const isc_statscounter_t tcp4statsindex[] = {
+	isc_sockstatscounter_tcp4open,	      isc_sockstatscounter_tcp4openfail,
+	isc_sockstatscounter_tcp4close,	      isc_sockstatscounter_tcp4bindfail,
+	isc_sockstatscounter_tcp4connectfail, isc_sockstatscounter_tcp4connect,
+	isc_sockstatscounter_tcp4acceptfail,  isc_sockstatscounter_tcp4accept,
+	isc_sockstatscounter_tcp4sendfail,    isc_sockstatscounter_tcp4recvfail,
+	isc_sockstatscounter_tcp4active
+};
+static const isc_statscounter_t tcp6statsindex[] = {
+	isc_sockstatscounter_tcp6open,	      isc_sockstatscounter_tcp6openfail,
+	isc_sockstatscounter_tcp6close,	      isc_sockstatscounter_tcp6bindfail,
+	isc_sockstatscounter_tcp6connectfail, isc_sockstatscounter_tcp6connect,
+	isc_sockstatscounter_tcp6acceptfail,  isc_sockstatscounter_tcp6accept,
+	isc_sockstatscounter_tcp6sendfail,    isc_sockstatscounter_tcp6recvfail,
+	isc_sockstatscounter_tcp6active
+};
+static const isc_statscounter_t unixstatsindex[] = {
+	isc_sockstatscounter_unixopen,	      isc_sockstatscounter_unixopenfail,
+	isc_sockstatscounter_unixclose,	      isc_sockstatscounter_unixbindfail,
+	isc_sockstatscounter_unixconnectfail, isc_sockstatscounter_unixconnect,
+	isc_sockstatscounter_unixacceptfail,  isc_sockstatscounter_unixaccept,
+	isc_sockstatscounter_unixsendfail,    isc_sockstatscounter_unixrecvfail,
+	isc_sockstatscounter_unixactive
+};
+static const isc_statscounter_t rawstatsindex[] = {
+	isc_sockstatscounter_rawopen,
+	isc_sockstatscounter_rawopenfail,
+	isc_sockstatscounter_rawclose,
+	-1,
+	-1,
+	-1,
+	-1,
+	-1,
+	-1,
+	isc_sockstatscounter_rawrecvfail,
+	isc_sockstatscounter_rawactive
+};
+
+static int
+gen_threadid(isc_socket_t *sock);
+
+static int
+gen_threadid(isc_socket_t *sock) {
+	return (sock->fd % sock->manager->nthreads);
+}
+
+static void
+manager_log(isc_socketmgr_t *sockmgr, isc_logcategory_t *category,
+	    isc_logmodule_t *module, int level, const char *fmt, ...)
+	ISC_FORMAT_PRINTF(5, 6);
+static void
+manager_log(isc_socketmgr_t *sockmgr, isc_logcategory_t *category,
+	    isc_logmodule_t *module, int level, const char *fmt, ...) {
+	char msgbuf[2048];
+	va_list ap;
+
+	if (!isc_log_wouldlog(isc_lctx, level)) {
+		return;
+	}
+
+	va_start(ap, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
+	va_end(ap);
+
+	isc_log_write(isc_lctx, category, module, level, "sockmgr %p: %s",
+		      sockmgr, msgbuf);
+}
+
+static void
+thread_log(isc__socketthread_t *thread, isc_logcategory_t *category,
+	   isc_logmodule_t *module, int level, const char *fmt, ...)
+	ISC_FORMAT_PRINTF(5, 6);
+static void
+thread_log(isc__socketthread_t *thread, isc_logcategory_t *category,
+	   isc_logmodule_t *module, int level, const char *fmt, ...) {
+	char msgbuf[2048];
+	va_list ap;
+
+	if (!isc_log_wouldlog(isc_lctx, level)) {
+		return;
+	}
+
+	va_start(ap, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
+	va_end(ap);
+
+	isc_log_write(isc_lctx, category, module, level,
+		      "sockmgr %p thread %d: %s", thread->manager,
+		      thread->threadid, msgbuf);
+}
+
+static void
+socket_log(isc_socket_t *sock, const isc_sockaddr_t *address,
+	   isc_logcategory_t *category, isc_logmodule_t *module, int level,
+	   const char *fmt, ...) ISC_FORMAT_PRINTF(6, 7);
+static void
+socket_log(isc_socket_t *sock, const isc_sockaddr_t *address,
+	   isc_logcategory_t *category, isc_logmodule_t *module, int level,
+	   const char *fmt, ...) {
+	char msgbuf[2048];
+	char peerbuf[ISC_SOCKADDR_FORMATSIZE];
+	va_list ap;
+
+	if (!isc_log_wouldlog(isc_lctx, level)) {
+		return;
+	}
+
+	va_start(ap, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
+	va_end(ap);
+
+	if (address == NULL) {
+		isc_log_write(isc_lctx, category, module, level,
+			      "socket %p: %s", sock, msgbuf);
+	} else {
+		isc_sockaddr_format(address, peerbuf, sizeof(peerbuf));
+		isc_log_write(isc_lctx, category, module, level,
+			      "socket %p %s: %s", sock, peerbuf, msgbuf);
+	}
+}
+
+/*%
+ * Increment socket-related statistics counters.
+ */
+static void
+inc_stats(isc_stats_t *stats, isc_statscounter_t counterid) {
+	REQUIRE(counterid != -1);
+
+	if (stats != NULL) {
+		isc_stats_increment(stats, counterid);
+	}
+}
+
+/*%
+ * Decrement socket-related statistics counters.
+ */
+static void
+dec_stats(isc_stats_t *stats, isc_statscounter_t counterid) {
+	REQUIRE(counterid != -1);
+
+	if (stats != NULL) {
+		isc_stats_decrement(stats, counterid);
+	}
+}
+
+static isc_result_t
+watch_fd(isc__socketthread_t *thread, int fd, int msg) {
+	isc_result_t result = ISC_R_SUCCESS;
+
+#ifdef USE_KQUEUE
+	struct kevent evchange;
+
+	memset(&evchange, 0, sizeof(evchange));
+	if (msg == SELECT_POKE_READ) {
+		evchange.filter = EVFILT_READ;
+	} else {
+		evchange.filter = EVFILT_WRITE;
+	}
+	evchange.flags = EV_ADD;
+	evchange.ident = fd;
+	if (kevent(thread->kqueue_fd, &evchange, 1, NULL, 0, NULL) != 0) {
+		result = isc__errno2result(errno);
+	}
+
+	return (result);
+#elif defined(USE_EPOLL)
+	struct epoll_event event;
+	uint32_t oldevents;
+	int ret;
+	int op;
+
+	oldevents = thread->epoll_events[fd];
+	if (msg == SELECT_POKE_READ) {
+		thread->epoll_events[fd] |= EPOLLIN;
+	} else {
+		thread->epoll_events[fd] |= EPOLLOUT;
+	}
+
+	event.events = thread->epoll_events[fd];
+	memset(&event.data, 0, sizeof(event.data));
+	event.data.fd = fd;
+
+	op = (oldevents == 0U) ? EPOLL_CTL_ADD : EPOLL_CTL_MOD;
+	if (thread->fds[fd] != NULL) {
+		LOCK(&thread->fds[fd]->lock);
+	}
+	ret = epoll_ctl(thread->epoll_fd, op, fd, &event);
+	if (thread->fds[fd] != NULL) {
+		UNLOCK(&thread->fds[fd]->lock);
+	}
+	if (ret == -1) {
+		if (errno == EEXIST) {
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "epoll_ctl(ADD/MOD) returned "
+					 "EEXIST for fd %d",
+					 fd);
+		}
+		result = isc__errno2result(errno);
+	}
+
+	return (result);
+#elif defined(USE_DEVPOLL)
+	struct pollfd pfd;
+
+	memset(&pfd, 0, sizeof(pfd));
+	if (msg == SELECT_POKE_READ) {
+		pfd.events = POLLIN;
+	} else {
+		pfd.events = POLLOUT;
+	}
+	pfd.fd = fd;
+	pfd.revents = 0;
+	if (write(thread->devpoll_fd, &pfd, sizeof(pfd)) == -1) {
+		result = isc__errno2result(errno);
+	} else {
+		if (msg == SELECT_POKE_READ) {
+			thread->fdpollinfo[fd].want_read = 1;
+		} else {
+			thread->fdpollinfo[fd].want_write = 1;
+		}
+	}
+
+	return (result);
+#elif defined(USE_SELECT)
+	LOCK(&thread->manager->lock);
+	if (msg == SELECT_POKE_READ) {
+		FD_SET(fd, thread->read_fds);
+	}
+	if (msg == SELECT_POKE_WRITE) {
+		FD_SET(fd, thread->write_fds);
+	}
+	UNLOCK(&thread->manager->lock);
+
+	return (result);
+#endif /* ifdef USE_KQUEUE */
+}
+
+static isc_result_t
+unwatch_fd(isc__socketthread_t *thread, int fd, int msg) {
+	isc_result_t result = ISC_R_SUCCESS;
+
+#ifdef USE_KQUEUE
+	struct kevent evchange;
+
+	memset(&evchange, 0, sizeof(evchange));
+	if (msg == SELECT_POKE_READ) {
+		evchange.filter = EVFILT_READ;
+	} else {
+		evchange.filter = EVFILT_WRITE;
+	}
+	evchange.flags = EV_DELETE;
+	evchange.ident = fd;
+	if (kevent(thread->kqueue_fd, &evchange, 1, NULL, 0, NULL) != 0) {
+		result = isc__errno2result(errno);
+	}
+
+	return (result);
+#elif defined(USE_EPOLL)
+	struct epoll_event event;
+	int ret;
+	int op;
+
+	if (msg == SELECT_POKE_READ) {
+		thread->epoll_events[fd] &= ~(EPOLLIN);
+	} else {
+		thread->epoll_events[fd] &= ~(EPOLLOUT);
+	}
+
+	event.events = thread->epoll_events[fd];
+	memset(&event.data, 0, sizeof(event.data));
+	event.data.fd = fd;
+
+	op = (event.events == 0U) ? EPOLL_CTL_DEL : EPOLL_CTL_MOD;
+	ret = epoll_ctl(thread->epoll_fd, op, fd, &event);
+	if (ret == -1 && errno != ENOENT) {
+		char strbuf[ISC_STRERRORSIZE];
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "epoll_ctl(DEL), %d: %s",
+				 fd, strbuf);
+		result = ISC_R_UNEXPECTED;
+	}
+	return (result);
+#elif defined(USE_DEVPOLL)
+	struct pollfd pfds[2];
+	size_t writelen = sizeof(pfds[0]);
+
+	memset(pfds, 0, sizeof(pfds));
+	pfds[0].events = POLLREMOVE;
+	pfds[0].fd = fd;
+
+	/*
+	 * Canceling read or write polling via /dev/poll is tricky.  Since it
+	 * only provides a way of canceling per FD, we may need to re-poll the
+	 * socket for the other operation.
+	 */
+	if (msg == SELECT_POKE_READ && thread->fdpollinfo[fd].want_write == 1) {
+		pfds[1].events = POLLOUT;
+		pfds[1].fd = fd;
+		writelen += sizeof(pfds[1]);
+	}
+	if (msg == SELECT_POKE_WRITE && thread->fdpollinfo[fd].want_read == 1) {
+		pfds[1].events = POLLIN;
+		pfds[1].fd = fd;
+		writelen += sizeof(pfds[1]);
+	}
+
+	if (write(thread->devpoll_fd, pfds, writelen) == -1) {
+		result = isc__errno2result(errno);
+	} else {
+		if (msg == SELECT_POKE_READ) {
+			thread->fdpollinfo[fd].want_read = 0;
+		} else {
+			thread->fdpollinfo[fd].want_write = 0;
+		}
+	}
+
+	return (result);
+#elif defined(USE_SELECT)
+	LOCK(&thread->manager->lock);
+	if (msg == SELECT_POKE_READ) {
+		FD_CLR(fd, thread->read_fds);
+	} else if (msg == SELECT_POKE_WRITE) {
+		FD_CLR(fd, thread->write_fds);
+	}
+	UNLOCK(&thread->manager->lock);
+
+	return (result);
+#endif /* ifdef USE_KQUEUE */
+}
+
+/*
+ * A poke message was received, perform a proper watch/unwatch
+ * on a fd provided
+ */
+static void
+wakeup_socket(isc__socketthread_t *thread, int fd, int msg) {
+	isc_result_t result;
+	int lockid = FDLOCK_ID(fd);
+
+	/*
+	 * This is a wakeup on a socket.  If the socket is not in the
+	 * process of being closed, start watching it for either reads
+	 * or writes.
+	 */
+
+	INSIST(fd >= 0 && fd < (int)thread->manager->maxsocks);
+
+	if (msg == SELECT_POKE_CLOSE) {
+		LOCK(&thread->fdlock[lockid]);
+		INSIST(thread->fdstate[fd] == CLOSE_PENDING);
+		thread->fdstate[fd] = CLOSED;
+		(void)unwatch_fd(thread, fd, SELECT_POKE_READ);
+		(void)unwatch_fd(thread, fd, SELECT_POKE_WRITE);
+		(void)close(fd);
+		UNLOCK(&thread->fdlock[lockid]);
+		return;
+	}
+
+	LOCK(&thread->fdlock[lockid]);
+	if (thread->fdstate[fd] == CLOSE_PENDING) {
+		/*
+		 * We accept (and ignore) any error from unwatch_fd() as we are
+		 * closing the socket, hoping it doesn't leave dangling state in
+		 * the kernel.
+		 * Note that unwatch_fd() must be called after releasing the
+		 * fdlock; otherwise it could cause deadlock due to a lock order
+		 * reversal.
+		 */
+		(void)unwatch_fd(thread, fd, SELECT_POKE_READ);
+		(void)unwatch_fd(thread, fd, SELECT_POKE_WRITE);
+		UNLOCK(&thread->fdlock[lockid]);
+		return;
+	}
+	if (thread->fdstate[fd] != MANAGED) {
+		UNLOCK(&thread->fdlock[lockid]);
+		return;
+	}
+
+	/*
+	 * Set requested bit.
+	 */
+	result = watch_fd(thread, fd, msg);
+	if (result != ISC_R_SUCCESS) {
+		/*
+		 * XXXJT: what should we do?  Ignoring the failure of watching
+		 * a socket will make the application dysfunctional, but there
+		 * seems to be no reasonable recovery process.
+		 */
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+			      "failed to start watching FD (%d): %s", fd,
+			      isc_result_totext(result));
+	}
+	UNLOCK(&thread->fdlock[lockid]);
+}
+
+/*
+ * Poke the select loop when there is something for us to do.
+ * The write is required (by POSIX) to complete.  That is, we
+ * will not get partial writes.
+ */
+static void
+select_poke(isc_socketmgr_t *mgr, int threadid, int fd, int msg) {
+	int cc;
+	int buf[2];
+	char strbuf[ISC_STRERRORSIZE];
+
+	buf[0] = fd;
+	buf[1] = msg;
+
+	do {
+		cc = write(mgr->threads[threadid].pipe_fds[1], buf,
+			   sizeof(buf));
+#ifdef ENOSR
+		/*
+		 * Treat ENOSR as EAGAIN but loop slowly as it is
+		 * unlikely to clear fast.
+		 */
+		if (cc < 0 && errno == ENOSR) {
+			sleep(1);
+			errno = EAGAIN;
+		}
+#endif /* ifdef ENOSR */
+	} while (cc < 0 && SOFT_ERROR(errno));
+
+	if (cc < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		FATAL_ERROR(__FILE__, __LINE__,
+			    "write() failed during watcher poke: %s", strbuf);
+	}
+
+	INSIST(cc == sizeof(buf));
+}
+
+/*
+ * Read a message on the internal fd.
+ */
+static void
+select_readmsg(isc__socketthread_t *thread, int *fd, int *msg) {
+	int buf[2];
+	int cc;
+	char strbuf[ISC_STRERRORSIZE];
+
+	cc = read(thread->pipe_fds[0], buf, sizeof(buf));
+	if (cc < 0) {
+		*msg = SELECT_POKE_NOTHING;
+		*fd = -1; /* Silence compiler. */
+		if (SOFT_ERROR(errno)) {
+			return;
+		}
+
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		FATAL_ERROR(__FILE__, __LINE__,
+			    "read() failed during watcher poke: %s", strbuf);
+	}
+	INSIST(cc == sizeof(buf));
+
+	*fd = buf[0];
+	*msg = buf[1];
+}
+
+/*
+ * Make a fd non-blocking.
+ */
+static isc_result_t
+make_nonblock(int fd) {
+	int ret;
+	char strbuf[ISC_STRERRORSIZE];
+#ifdef USE_FIONBIO_IOCTL
+	int on = 1;
+#else  /* ifdef USE_FIONBIO_IOCTL */
+	int flags;
+#endif /* ifdef USE_FIONBIO_IOCTL */
+
+#ifdef USE_FIONBIO_IOCTL
+	ret = ioctl(fd, FIONBIO, (char *)&on);
+#else  /* ifdef USE_FIONBIO_IOCTL */
+	flags = fcntl(fd, F_GETFL, 0);
+	flags |= PORT_NONBLOCK;
+	ret = fcntl(fd, F_SETFL, flags);
+#endif /* ifdef USE_FIONBIO_IOCTL */
+
+	if (ret == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+#ifdef USE_FIONBIO_IOCTL
+				 "ioctl(%d, FIONBIO, &on): %s", fd,
+#else  /* ifdef USE_FIONBIO_IOCTL */
+				 "fcntl(%d, F_SETFL, %d): %s", fd, flags,
+#endif /* ifdef USE_FIONBIO_IOCTL */
+				 strbuf);
+
+		return (ISC_R_UNEXPECTED);
+	}
+
+	return (ISC_R_SUCCESS);
+}
+
+#ifdef USE_CMSG
+/*
+ * Not all OSes support advanced CMSG macros: CMSG_LEN and CMSG_SPACE.
+ * In order to ensure as much portability as possible, we provide wrapper
+ * functions of these macros.
+ * Note that cmsg_space() could run slow on OSes that do not have
+ * CMSG_SPACE.
+ */
+static socklen_t
+cmsg_len(socklen_t len) {
+#ifdef CMSG_LEN
+	return (CMSG_LEN(len));
+#else  /* ifdef CMSG_LEN */
+	socklen_t hdrlen;
+
+	/*
+	 * Cast NULL so that any pointer arithmetic performed by CMSG_DATA
+	 * is correct.
+	 */
+	hdrlen = (socklen_t)CMSG_DATA(((struct cmsghdr *)NULL));
+	return (hdrlen + len);
+#endif /* ifdef CMSG_LEN */
+}
+
+static socklen_t
+cmsg_space(socklen_t len) {
+#ifdef CMSG_SPACE
+	return (CMSG_SPACE(len));
+#else  /* ifdef CMSG_SPACE */
+	struct msghdr msg;
+	struct cmsghdr *cmsgp;
+	/*
+	 * XXX: The buffer length is an ad-hoc value, but should be enough
+	 * in a practical sense.
+	 */
+	char dummybuf[sizeof(struct cmsghdr) + 1024];
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_control = dummybuf;
+	msg.msg_controllen = sizeof(dummybuf);
+
+	cmsgp = (struct cmsghdr *)dummybuf;
+	cmsgp->cmsg_len = cmsg_len(len);
+
+	cmsgp = CMSG_NXTHDR(&msg, cmsgp);
+	if (cmsgp != NULL) {
+		return ((char *)cmsgp - (char *)msg.msg_control);
+	} else {
+		return (0);
+	}
+#endif /* ifdef CMSG_SPACE */
+}
+#endif /* USE_CMSG */
+
+/*
+ * Process control messages received on a socket.
+ */
+static void
+process_cmsg(isc_socket_t *sock, struct msghdr *msg, isc_socketevent_t *dev) {
+#ifdef USE_CMSG
+	struct cmsghdr *cmsgp;
+	struct in6_pktinfo *pktinfop;
+#ifdef SO_TIMESTAMP
+	void *timevalp;
+#endif /* ifdef SO_TIMESTAMP */
+#endif /* ifdef USE_CMSG */
+
+	/*
+	 * sock is used only when ISC_NET_BSD44MSGHDR and USE_CMSG are defined.
+	 * msg and dev are used only when ISC_NET_BSD44MSGHDR is defined.
+	 * They are all here, outside of the CPP tests, because it is
+	 * more consistent with the usual ISC coding style.
+	 */
+	UNUSED(sock);
+	UNUSED(msg);
+	UNUSED(dev);
+
+#ifdef MSG_TRUNC
+	if ((msg->msg_flags & MSG_TRUNC) != 0) {
+		dev->attributes |= ISC_SOCKEVENTATTR_TRUNC;
+	}
+#endif /* ifdef MSG_TRUNC */
+
+#ifdef MSG_CTRUNC
+	if ((msg->msg_flags & MSG_CTRUNC) != 0) {
+		dev->attributes |= ISC_SOCKEVENTATTR_CTRUNC;
+	}
+#endif /* ifdef MSG_CTRUNC */
+
+#ifndef USE_CMSG
+	return;
+#else /* ifndef USE_CMSG */
+	if (msg->msg_controllen == 0U || msg->msg_control == NULL) {
+		return;
+	}
+
+#ifdef SO_TIMESTAMP
+	timevalp = NULL;
+#endif /* ifdef SO_TIMESTAMP */
+	pktinfop = NULL;
+
+	cmsgp = CMSG_FIRSTHDR(msg);
+	while (cmsgp != NULL) {
+		socket_log(sock, NULL, TRACE, "processing cmsg %p", cmsgp);
+
+		if (cmsgp->cmsg_level == IPPROTO_IPV6 &&
+		    cmsgp->cmsg_type == IPV6_PKTINFO)
+		{
+			pktinfop = (struct in6_pktinfo *)CMSG_DATA(cmsgp);
+			memmove(&dev->pktinfo, pktinfop,
+				sizeof(struct in6_pktinfo));
+			dev->attributes |= ISC_SOCKEVENTATTR_PKTINFO;
+			socket_log(sock, NULL, TRACE,
+				   "interface received on ifindex %u",
+				   dev->pktinfo.ipi6_ifindex);
+			if (IN6_IS_ADDR_MULTICAST(&pktinfop->ipi6_addr)) {
+				dev->attributes |= ISC_SOCKEVENTATTR_MULTICAST;
+			}
+			goto next;
+		}
+
+#ifdef SO_TIMESTAMP
+		if (cmsgp->cmsg_level == SOL_SOCKET &&
+		    cmsgp->cmsg_type == SCM_TIMESTAMP)
+		{
+			struct timeval tv;
+			timevalp = CMSG_DATA(cmsgp);
+			memmove(&tv, timevalp, sizeof(tv));
+			dev->timestamp.seconds = tv.tv_sec;
+			dev->timestamp.nanoseconds = tv.tv_usec * 1000;
+			dev->attributes |= ISC_SOCKEVENTATTR_TIMESTAMP;
+			goto next;
+		}
+#endif /* ifdef SO_TIMESTAMP */
+
+#ifdef IPV6_TCLASS
+		if (cmsgp->cmsg_level == IPPROTO_IPV6 &&
+		    cmsgp->cmsg_type == IPV6_TCLASS)
+		{
+			dev->dscp = *(int *)CMSG_DATA(cmsgp);
+			dev->dscp >>= 2;
+			dev->attributes |= ISC_SOCKEVENTATTR_DSCP;
+			goto next;
+		}
+#endif /* ifdef IPV6_TCLASS */
+
+#ifdef IP_TOS
+		if (cmsgp->cmsg_level == IPPROTO_IP &&
+		    (cmsgp->cmsg_type == IP_TOS
+#ifdef IP_RECVTOS
+		     || cmsgp->cmsg_type == IP_RECVTOS
+#endif /* ifdef IP_RECVTOS */
+		     ))
+		{
+			dev->dscp = (int)*(unsigned char *)CMSG_DATA(cmsgp);
+			dev->dscp >>= 2;
+			dev->attributes |= ISC_SOCKEVENTATTR_DSCP;
+			goto next;
+		}
+#endif /* ifdef IP_TOS */
+	next:
+		cmsgp = CMSG_NXTHDR(msg, cmsgp);
+	}
+#endif /* USE_CMSG */
+}
+
+/*
+ * Construct an iov array and attach it to the msghdr passed in.  This is
+ * the SEND constructor, which will use the used region of the buffer
+ * (if using a buffer list) or will use the internal region (if a single
+ * buffer I/O is requested).
+ *
+ * Nothing can be NULL, and the done event must list at least one buffer
+ * on the buffer linked list for this function to be meaningful.
+ *
+ * If write_countp != NULL, *write_countp will hold the number of bytes
+ * this transaction can send.
+ */
+static void
+build_msghdr_send(isc_socket_t *sock, char *cmsgbuf, isc_socketevent_t *dev,
+		  struct msghdr *msg, struct iovec *iov, size_t *write_countp) {
+	unsigned int iovcount;
+	size_t write_count;
+	struct cmsghdr *cmsgp;
+
+	memset(msg, 0, sizeof(*msg));
+
+	if (!sock->connected) {
+		msg->msg_name = (void *)&dev->address.type.sa;
+		msg->msg_namelen = dev->address.length;
+	} else {
+		msg->msg_name = NULL;
+		msg->msg_namelen = 0;
+	}
+
+	write_count = dev->region.length - dev->n;
+	iov[0].iov_base = (void *)(dev->region.base + dev->n);
+	iov[0].iov_len = write_count;
+	iovcount = 1;
+
+	msg->msg_iov = iov;
+	msg->msg_iovlen = iovcount;
+	msg->msg_control = NULL;
+	msg->msg_controllen = 0;
+	msg->msg_flags = 0;
+#if defined(USE_CMSG)
+
+	if ((sock->type == isc_sockettype_udp) &&
+	    ((dev->attributes & ISC_SOCKEVENTATTR_PKTINFO) != 0))
+	{
+		struct in6_pktinfo *pktinfop;
+
+		socket_log(sock, NULL, TRACE, "sendto pktinfo data, ifindex %u",
+			   dev->pktinfo.ipi6_ifindex);
+
+		msg->msg_control = (void *)cmsgbuf;
+		msg->msg_controllen = cmsg_space(sizeof(struct in6_pktinfo));
+		INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
+
+		cmsgp = (struct cmsghdr *)cmsgbuf;
+		cmsgp->cmsg_level = IPPROTO_IPV6;
+		cmsgp->cmsg_type = IPV6_PKTINFO;
+		cmsgp->cmsg_len = cmsg_len(sizeof(struct in6_pktinfo));
+		pktinfop = (struct in6_pktinfo *)CMSG_DATA(cmsgp);
+		memmove(pktinfop, &dev->pktinfo, sizeof(struct in6_pktinfo));
+	}
+
+#if defined(IPV6_USE_MIN_MTU)
+	if ((sock->type == isc_sockettype_udp) && (sock->pf == AF_INET6) &&
+	    ((dev->attributes & ISC_SOCKEVENTATTR_USEMINMTU) != 0))
+	{
+		int use_min_mtu = 1; /* -1, 0, 1 */
+
+		cmsgp = (struct cmsghdr *)(cmsgbuf + msg->msg_controllen);
+		msg->msg_control = (void *)cmsgbuf;
+		msg->msg_controllen += cmsg_space(sizeof(use_min_mtu));
+		INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
+
+		cmsgp->cmsg_level = IPPROTO_IPV6;
+		cmsgp->cmsg_type = IPV6_USE_MIN_MTU;
+		cmsgp->cmsg_len = cmsg_len(sizeof(use_min_mtu));
+		memmove(CMSG_DATA(cmsgp), &use_min_mtu, sizeof(use_min_mtu));
+	}
+#endif /* if defined(IPV6_USE_MIN_MTU) */
+
+	if (isc_dscp_check_value > -1) {
+		if (sock->type == isc_sockettype_udp) {
+			INSIST((int)dev->dscp == isc_dscp_check_value);
+		} else if (sock->type == isc_sockettype_tcp) {
+			INSIST((int)sock->dscp == isc_dscp_check_value);
+		}
+	}
+
+#if defined(IP_TOS) || (defined(IPPROTO_IPV6) && defined(IPV6_TCLASS))
+	if ((sock->type == isc_sockettype_udp) &&
+	    ((dev->attributes & ISC_SOCKEVENTATTR_DSCP) != 0))
+	{
+		int dscp = (dev->dscp << 2) & 0xff;
+
+		INSIST(dev->dscp < 0x40);
+
+#ifdef IP_TOS
+		if (sock->pf == AF_INET && sock->pktdscp) {
+			cmsgp = (struct cmsghdr *)(cmsgbuf +
+						   msg->msg_controllen);
+			msg->msg_control = (void *)cmsgbuf;
+			msg->msg_controllen += cmsg_space(sizeof(dscp));
+			INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
+
+			cmsgp->cmsg_level = IPPROTO_IP;
+			cmsgp->cmsg_type = IP_TOS;
+			cmsgp->cmsg_len = cmsg_len(sizeof(char));
+			*(unsigned char *)CMSG_DATA(cmsgp) = dscp;
+		} else if (sock->pf == AF_INET && sock->dscp != dev->dscp) {
+			if (setsockopt(sock->fd, IPPROTO_IP, IP_TOS,
+				       (void *)&dscp, sizeof(int)) < 0)
+			{
+				char strbuf[ISC_STRERRORSIZE];
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				UNEXPECTED_ERROR(__FILE__, __LINE__,
+						 "setsockopt(%d, IP_TOS, %.02x)"
+						 " failed: %s",
+						 sock->fd, dscp >> 2, strbuf);
+			} else {
+				sock->dscp = dscp;
+			}
+		}
+#endif /* ifdef IP_TOS */
+#if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS)
+		if (sock->pf == AF_INET6 && sock->pktdscp) {
+			cmsgp = (struct cmsghdr *)(cmsgbuf +
+						   msg->msg_controllen);
+			msg->msg_control = (void *)cmsgbuf;
+			msg->msg_controllen += cmsg_space(sizeof(dscp));
+			INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
+
+			cmsgp->cmsg_level = IPPROTO_IPV6;
+			cmsgp->cmsg_type = IPV6_TCLASS;
+			cmsgp->cmsg_len = cmsg_len(sizeof(dscp));
+			memmove(CMSG_DATA(cmsgp), &dscp, sizeof(dscp));
+		} else if (sock->pf == AF_INET6 && sock->dscp != dev->dscp) {
+			if (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_TCLASS,
+				       (void *)&dscp, sizeof(int)) < 0)
+			{
+				char strbuf[ISC_STRERRORSIZE];
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				UNEXPECTED_ERROR(__FILE__, __LINE__,
+						 "setsockopt(%d, IPV6_TCLASS, "
+						 "%.02x) failed: %s",
+						 sock->fd, dscp >> 2, strbuf);
+			} else {
+				sock->dscp = dscp;
+			}
+		}
+#endif /* if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS) */
+		if (msg->msg_controllen != 0 &&
+		    msg->msg_controllen < SENDCMSGBUFLEN)
+		{
+			memset(cmsgbuf + msg->msg_controllen, 0,
+			       SENDCMSGBUFLEN - msg->msg_controllen);
+		}
+	}
+#endif /* if defined(IP_TOS) || (defined(IPPROTO_IPV6) && \
+	* defined(IPV6_TCLASS))                           \
+	* */
+#endif /* USE_CMSG */
+
+	if (write_countp != NULL) {
+		*write_countp = write_count;
+	}
+}
+
+/*
+ * Construct an iov array and attach it to the msghdr passed in.  This is
+ * the RECV constructor, which will use the available region of the buffer
+ * (if using a buffer list) or will use the internal region (if a single
+ * buffer I/O is requested).
+ *
+ * Nothing can be NULL, and the done event must list at least one buffer
+ * on the buffer linked list for this function to be meaningful.
+ *
+ * If read_countp != NULL, *read_countp will hold the number of bytes
+ * this transaction can receive.
+ */
+static void
+build_msghdr_recv(isc_socket_t *sock, char *cmsgbuf, isc_socketevent_t *dev,
+		  struct msghdr *msg, struct iovec *iov, size_t *read_countp) {
+	unsigned int iovcount;
+	size_t read_count;
+
+	memset(msg, 0, sizeof(struct msghdr));
+
+	if (sock->type == isc_sockettype_udp) {
+		memset(&dev->address, 0, sizeof(dev->address));
+		msg->msg_name = (void *)&dev->address.type.sa;
+		msg->msg_namelen = sizeof(dev->address.type);
+	} else { /* TCP */
+		msg->msg_name = NULL;
+		msg->msg_namelen = 0;
+		dev->address = sock->peer_address;
+	}
+
+	read_count = dev->region.length - dev->n;
+	iov[0].iov_base = (void *)(dev->region.base + dev->n);
+	iov[0].iov_len = read_count;
+	iovcount = 1;
+
+	/*
+	 * If needed, set up to receive that one extra byte.
+	 */
+#ifdef ISC_PLATFORM_RECVOVERFLOW
+	if (sock->type == isc_sockettype_udp) {
+		INSIST(iovcount < MAXSCATTERGATHER_RECV);
+		iov[iovcount].iov_base = (void *)(&sock->overflow);
+		iov[iovcount].iov_len = 1;
+		iovcount++;
+	}
+#endif /* ifdef ISC_PLATFORM_RECVOVERFLOW */
+
+	msg->msg_iov = iov;
+	msg->msg_iovlen = iovcount;
+
+#if defined(USE_CMSG)
+	msg->msg_control = cmsgbuf;
+	msg->msg_controllen = RECVCMSGBUFLEN;
+#else  /* if defined(USE_CMSG) */
+	msg->msg_control = NULL;
+	msg->msg_controllen = 0;
+#endif /* USE_CMSG */
+	msg->msg_flags = 0;
+
+	if (read_countp != NULL) {
+		*read_countp = read_count;
+	}
+}
+
+static void
+set_dev_address(const isc_sockaddr_t *address, isc_socket_t *sock,
+		isc_socketevent_t *dev) {
+	if (sock->type == isc_sockettype_udp) {
+		if (address != NULL) {
+			dev->address = *address;
+		} else {
+			dev->address = sock->peer_address;
+		}
+	} else if (sock->type == isc_sockettype_tcp) {
+		INSIST(address == NULL);
+		dev->address = sock->peer_address;
+	}
+}
+
+static void
+destroy_socketevent(isc_event_t *event) {
+	isc_socketevent_t *ev = (isc_socketevent_t *)event;
+
+	(ev->destroy)(event);
+}
+
+static isc_socketevent_t *
+allocate_socketevent(isc_mem_t *mctx, void *sender, isc_eventtype_t eventtype,
+		     isc_taskaction_t action, void *arg) {
+	isc_socketevent_t *ev;
+
+	ev = (isc_socketevent_t *)isc_event_allocate(mctx, sender, eventtype,
+						     action, arg, sizeof(*ev));
+
+	ev->result = ISC_R_UNSET;
+	ISC_LINK_INIT(ev, ev_link);
+	ev->region.base = NULL;
+	ev->n = 0;
+	ev->offset = 0;
+	ev->attributes = 0;
+	ev->destroy = ev->ev_destroy;
+	ev->ev_destroy = destroy_socketevent;
+	ev->dscp = 0;
+
+	return (ev);
+}
+
+#if defined(ISC_SOCKET_DEBUG)
+static void
+dump_msg(struct msghdr *msg) {
+	unsigned int i;
+
+	printf("MSGHDR %p\n", msg);
+	printf("\tname %p, namelen %ld\n", msg->msg_name,
+	       (long)msg->msg_namelen);
+	printf("\tiov %p, iovlen %ld\n", msg->msg_iov, (long)msg->msg_iovlen);
+	for (i = 0; i < (unsigned int)msg->msg_iovlen; i++) {
+		printf("\t\t%u\tbase %p, len %ld\n", i,
+		       msg->msg_iov[i].iov_base, (long)msg->msg_iov[i].iov_len);
+	}
+	printf("\tcontrol %p, controllen %ld\n", msg->msg_control,
+	       (long)msg->msg_controllen);
+}
+#endif /* if defined(ISC_SOCKET_DEBUG) */
+
+#define DOIO_SUCCESS 0 /* i/o ok, event sent */
+#define DOIO_SOFT    1 /* i/o ok, soft error, no event sent */
+#define DOIO_HARD    2 /* i/o error, event sent */
+#define DOIO_EOF     3 /* EOF, no event sent */
+
+static int
+doio_recv(isc_socket_t *sock, isc_socketevent_t *dev) {
+	int cc;
+	struct iovec iov[MAXSCATTERGATHER_RECV];
+	size_t read_count;
+	struct msghdr msghdr;
+	int recv_errno;
+	char strbuf[ISC_STRERRORSIZE];
+	char cmsgbuf[RECVCMSGBUFLEN] = { 0 };
+
+	build_msghdr_recv(sock, cmsgbuf, dev, &msghdr, iov, &read_count);
+
+#if defined(ISC_SOCKET_DEBUG)
+	dump_msg(&msghdr);
+#endif /* if defined(ISC_SOCKET_DEBUG) */
+
+	cc = recvmsg(sock->fd, &msghdr, 0);
+	recv_errno = errno;
+
+#if defined(ISC_SOCKET_DEBUG)
+	dump_msg(&msghdr);
+#endif /* if defined(ISC_SOCKET_DEBUG) */
+
+	if (cc < 0) {
+		if (SOFT_ERROR(recv_errno)) {
+			return (DOIO_SOFT);
+		}
+
+		if (isc_log_wouldlog(isc_lctx, IOEVENT_LEVEL)) {
+			strerror_r(recv_errno, strbuf, sizeof(strbuf));
+			socket_log(sock, NULL, IOEVENT,
+				   "doio_recv: recvmsg(%d) %d bytes, err %d/%s",
+				   sock->fd, cc, recv_errno, strbuf);
+		}
+
+#define SOFT_OR_HARD(_system, _isc)                                   \
+	if (recv_errno == _system) {                                  \
+		if (sock->connected) {                                \
+			dev->result = _isc;                           \
+			inc_stats(sock->manager->stats,               \
+				  sock->statsindex[STATID_RECVFAIL]); \
+			return (DOIO_HARD);                           \
+		}                                                     \
+		return (DOIO_SOFT);                                   \
+	}
+#define ALWAYS_HARD(_system, _isc)                            \
+	if (recv_errno == _system) {                          \
+		dev->result = _isc;                           \
+		inc_stats(sock->manager->stats,               \
+			  sock->statsindex[STATID_RECVFAIL]); \
+		return (DOIO_HARD);                           \
+	}
+
+		SOFT_OR_HARD(ECONNREFUSED, ISC_R_CONNREFUSED);
+		SOFT_OR_HARD(ENETUNREACH, ISC_R_NETUNREACH);
+		SOFT_OR_HARD(EHOSTUNREACH, ISC_R_HOSTUNREACH);
+		SOFT_OR_HARD(EHOSTDOWN, ISC_R_HOSTDOWN);
+		SOFT_OR_HARD(ENOBUFS, ISC_R_NORESOURCES);
+		/*
+		 * Older operating systems may still return EPROTO in some
+		 * situations, for example when receiving ICMP/ICMPv6 errors.
+		 * A real life scenario is when ICMPv6 returns code 5 or 6.
+		 * These codes are introduced in RFC 4443 from March 2006,
+		 * and the document obsoletes RFC 1885. But unfortunately not
+		 * all operating systems have caught up with the new standard
+		 * (in 2020) and thus a generic protocol error is returned.
+		 */
+		SOFT_OR_HARD(EPROTO, ISC_R_HOSTUNREACH);
+		/* Should never get this one but it was seen. */
+#ifdef ENOPROTOOPT
+		SOFT_OR_HARD(ENOPROTOOPT, ISC_R_HOSTUNREACH);
+#endif /* ifdef ENOPROTOOPT */
+		SOFT_OR_HARD(EINVAL, ISC_R_HOSTUNREACH);
+
+#undef SOFT_OR_HARD
+#undef ALWAYS_HARD
+
+		dev->result = isc__errno2result(recv_errno);
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_RECVFAIL]);
+		return (DOIO_HARD);
+	}
+
+	/*
+	 * On TCP and UNIX sockets, zero length reads indicate EOF,
+	 * while on UDP sockets, zero length reads are perfectly valid,
+	 * although strange.
+	 */
+	switch (sock->type) {
+	case isc_sockettype_tcp:
+	case isc_sockettype_unix:
+		if (cc == 0) {
+			return (DOIO_EOF);
+		}
+		break;
+	case isc_sockettype_udp:
+	case isc_sockettype_raw:
+		break;
+	default:
+		UNREACHABLE();
+	}
+
+	if (sock->type == isc_sockettype_udp) {
+		dev->address.length = msghdr.msg_namelen;
+		if (isc_sockaddr_getport(&dev->address) == 0) {
+			if (isc_log_wouldlog(isc_lctx, IOEVENT_LEVEL)) {
+				socket_log(sock, &dev->address, IOEVENT,
+					   "dropping source port zero packet");
+			}
+			return (DOIO_SOFT);
+		}
+		/*
+		 * Simulate a firewall blocking UDP responses bigger than
+		 * 'maxudp' bytes.
+		 */
+		if (sock->manager->maxudp != 0 &&
+		    cc > (int)sock->manager->maxudp)
+		{
+			return (DOIO_SOFT);
+		}
+	}
+
+	socket_log(sock, &dev->address, IOEVENT, "packet received correctly");
+
+	/*
+	 * Overflow bit detection.  If we received MORE bytes than we should,
+	 * this indicates an overflow situation.  Set the flag in the
+	 * dev entry and adjust how much we read by one.
+	 */
+#ifdef ISC_PLATFORM_RECVOVERFLOW
+	if ((sock->type == isc_sockettype_udp) && ((size_t)cc > read_count)) {
+		dev->attributes |= ISC_SOCKEVENTATTR_TRUNC;
+		cc--;
+	}
+#endif /* ifdef ISC_PLATFORM_RECVOVERFLOW */
+
+	/*
+	 * If there are control messages attached, run through them and pull
+	 * out the interesting bits.
+	 */
+	process_cmsg(sock, &msghdr, dev);
+
+	/*
+	 * update the buffers (if any) and the i/o count
+	 */
+	dev->n += cc;
+
+	/*
+	 * If we read less than we expected, update counters,
+	 * and let the upper layer poke the descriptor.
+	 */
+	if (((size_t)cc != read_count) && (dev->n < dev->minimum)) {
+		return (DOIO_SOFT);
+	}
+
+	/*
+	 * Full reads are posted, or partials if partials are ok.
+	 */
+	dev->result = ISC_R_SUCCESS;
+	return (DOIO_SUCCESS);
+}
+
+/*
+ * Returns:
+ *	DOIO_SUCCESS	The operation succeeded.  dev->result contains
+ *			ISC_R_SUCCESS.
+ *
+ *	DOIO_HARD	A hard or unexpected I/O error was encountered.
+ *			dev->result contains the appropriate error.
+ *
+ *	DOIO_SOFT	A soft I/O error was encountered.  No senddone
+ *			event was sent.  The operation should be retried.
+ *
+ *	No other return values are possible.
+ */
+static int
+doio_send(isc_socket_t *sock, isc_socketevent_t *dev) {
+	int cc;
+	struct iovec iov[MAXSCATTERGATHER_SEND];
+	size_t write_count;
+	struct msghdr msghdr;
+	char addrbuf[ISC_SOCKADDR_FORMATSIZE];
+	int attempts = 0;
+	int send_errno;
+	char strbuf[ISC_STRERRORSIZE];
+	char cmsgbuf[SENDCMSGBUFLEN] = { 0 };
+
+	build_msghdr_send(sock, cmsgbuf, dev, &msghdr, iov, &write_count);
+
+resend:
+	if (sock->type == isc_sockettype_udp && sock->manager->maxudp != 0 &&
+	    write_count > sock->manager->maxudp)
+	{
+		cc = write_count;
+	} else {
+		cc = sendmsg(sock->fd, &msghdr, 0);
+	}
+	send_errno = errno;
+
+	/*
+	 * Check for error or block condition.
+	 */
+	if (cc < 0) {
+		if (send_errno == EINTR && ++attempts < NRETRIES) {
+			goto resend;
+		}
+
+		if (SOFT_ERROR(send_errno)) {
+			if (errno == EWOULDBLOCK || errno == EAGAIN) {
+				dev->result = ISC_R_WOULDBLOCK;
+			}
+			return (DOIO_SOFT);
+		}
+
+#define SOFT_OR_HARD(_system, _isc)                                   \
+	if (send_errno == _system) {                                  \
+		if (sock->connected) {                                \
+			dev->result = _isc;                           \
+			inc_stats(sock->manager->stats,               \
+				  sock->statsindex[STATID_SENDFAIL]); \
+			return (DOIO_HARD);                           \
+		}                                                     \
+		return (DOIO_SOFT);                                   \
+	}
+#define ALWAYS_HARD(_system, _isc)                            \
+	if (send_errno == _system) {                          \
+		dev->result = _isc;                           \
+		inc_stats(sock->manager->stats,               \
+			  sock->statsindex[STATID_SENDFAIL]); \
+		return (DOIO_HARD);                           \
+	}
+
+		SOFT_OR_HARD(ECONNREFUSED, ISC_R_CONNREFUSED);
+		ALWAYS_HARD(EACCES, ISC_R_NOPERM);
+		ALWAYS_HARD(EAFNOSUPPORT, ISC_R_ADDRNOTAVAIL);
+		ALWAYS_HARD(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
+		ALWAYS_HARD(EHOSTUNREACH, ISC_R_HOSTUNREACH);
+#ifdef EHOSTDOWN
+		ALWAYS_HARD(EHOSTDOWN, ISC_R_HOSTUNREACH);
+#endif /* ifdef EHOSTDOWN */
+		ALWAYS_HARD(ENETUNREACH, ISC_R_NETUNREACH);
+		SOFT_OR_HARD(ENOBUFS, ISC_R_NORESOURCES);
+		ALWAYS_HARD(EPERM, ISC_R_HOSTUNREACH);
+		ALWAYS_HARD(EPIPE, ISC_R_NOTCONNECTED);
+		ALWAYS_HARD(ECONNRESET, ISC_R_CONNECTIONRESET);
+
+#undef SOFT_OR_HARD
+#undef ALWAYS_HARD
+
+		/*
+		 * The other error types depend on whether or not the
+		 * socket is UDP or TCP.  If it is UDP, some errors
+		 * that we expect to be fatal under TCP are merely
+		 * annoying, and are really soft errors.
+		 *
+		 * However, these soft errors are still returned as
+		 * a status.
+		 */
+		isc_sockaddr_format(&dev->address, addrbuf, sizeof(addrbuf));
+		strerror_r(send_errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "internal_send: %s: %s",
+				 addrbuf, strbuf);
+		dev->result = isc__errno2result(send_errno);
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_SENDFAIL]);
+		return (DOIO_HARD);
+	}
+
+	if (cc == 0) {
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_SENDFAIL]);
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "doio_send: send() returned 0");
+	}
+
+	/*
+	 * If we write less than we expected, update counters, poke.
+	 */
+	dev->n += cc;
+	if ((size_t)cc != write_count) {
+		return (DOIO_SOFT);
+	}
+
+	/*
+	 * Exactly what we wanted to write.  We're done with this
+	 * entry.  Post its completion event.
+	 */
+	dev->result = ISC_R_SUCCESS;
+	return (DOIO_SUCCESS);
+}
+
+/*
+ * Kill.
+ *
+ * Caller must ensure that the socket is not locked and no external
+ * references exist.
+ */
+static void
+socketclose(isc__socketthread_t *thread, isc_socket_t *sock, int fd) {
+	int lockid = FDLOCK_ID(fd);
+	/*
+	 * No one has this socket open, so the watcher doesn't have to be
+	 * poked, and the socket doesn't have to be locked.
+	 */
+	LOCK(&thread->fdlock[lockid]);
+	thread->fds[fd] = NULL;
+	thread->fdstate[fd] = CLOSE_PENDING;
+	UNLOCK(&thread->fdlock[lockid]);
+	select_poke(thread->manager, thread->threadid, fd, SELECT_POKE_CLOSE);
+
+	inc_stats(thread->manager->stats, sock->statsindex[STATID_CLOSE]);
+
+	LOCK(&sock->lock);
+	if (sock->active == 1) {
+		dec_stats(thread->manager->stats,
+			  sock->statsindex[STATID_ACTIVE]);
+		sock->active = 0;
+	}
+	UNLOCK(&sock->lock);
+
+	/*
+	 * update manager->maxfd here (XXX: this should be implemented more
+	 * efficiently)
+	 */
+#ifdef USE_SELECT
+	LOCK(&thread->manager->lock);
+	if (thread->maxfd == fd) {
+		int i;
+
+		thread->maxfd = 0;
+		for (i = fd - 1; i >= 0; i--) {
+			lockid = FDLOCK_ID(i);
+
+			LOCK(&thread->fdlock[lockid]);
+			if (thread->fdstate[i] == MANAGED) {
+				thread->maxfd = i;
+				UNLOCK(&thread->fdlock[lockid]);
+				break;
+			}
+			UNLOCK(&thread->fdlock[lockid]);
+		}
+		if (thread->maxfd < thread->pipe_fds[0]) {
+			thread->maxfd = thread->pipe_fds[0];
+		}
+	}
+
+	UNLOCK(&thread->manager->lock);
+#endif /* USE_SELECT */
+}
+
+static void
+destroy(isc_socket_t **sockp) {
+	int fd = 0;
+	isc_socket_t *sock = *sockp;
+	isc_socketmgr_t *manager = sock->manager;
+	isc__socketthread_t *thread = NULL;
+
+	socket_log(sock, NULL, CREATION, "destroying");
+
+	isc_refcount_destroy(&sock->references);
+
+	LOCK(&sock->lock);
+	INSIST(ISC_LIST_EMPTY(sock->connect_list));
+	INSIST(ISC_LIST_EMPTY(sock->accept_list));
+	INSIST(ISC_LIST_EMPTY(sock->recv_list));
+	INSIST(ISC_LIST_EMPTY(sock->send_list));
+	INSIST(sock->fd >= -1 && sock->fd < (int)manager->maxsocks);
+
+	if (sock->fd >= 0) {
+		fd = sock->fd;
+		thread = &manager->threads[sock->threadid];
+		sock->fd = -1;
+		sock->threadid = -1;
+	}
+	UNLOCK(&sock->lock);
+
+	if (fd > 0) {
+		socketclose(thread, sock, fd);
+	}
+
+	LOCK(&manager->lock);
+
+	ISC_LIST_UNLINK(manager->socklist, sock, link);
+
+	if (ISC_LIST_EMPTY(manager->socklist)) {
+		SIGNAL(&manager->shutdown_ok);
+	}
+
+	/* can't unlock manager as its memory context is still used */
+	free_socket(sockp);
+
+	UNLOCK(&manager->lock);
+}
+
+static isc_result_t
+allocate_socket(isc_socketmgr_t *manager, isc_sockettype_t type,
+		isc_socket_t **socketp) {
+	isc_socket_t *sock;
+
+	sock = isc_mem_get(manager->mctx, sizeof(*sock));
+
+	sock->magic = 0;
+	isc_refcount_init(&sock->references, 0);
+
+	sock->manager = manager;
+	sock->type = type;
+	sock->fd = -1;
+	sock->threadid = -1;
+	sock->dscp = 0; /* TOS/TCLASS is zero until set. */
+	sock->dupped = 0;
+	sock->statsindex = NULL;
+	sock->active = 0;
+
+	ISC_LINK_INIT(sock, link);
+
+	memset(sock->name, 0, sizeof(sock->name));
+	sock->tag = NULL;
+
+	/*
+	 * Set up list of readers and writers to be initially empty.
+	 */
+	ISC_LIST_INIT(sock->recv_list);
+	ISC_LIST_INIT(sock->send_list);
+	ISC_LIST_INIT(sock->accept_list);
+	ISC_LIST_INIT(sock->connect_list);
+
+	sock->listener = 0;
+	sock->connected = 0;
+	sock->connecting = 0;
+	sock->bound = 0;
+	sock->pktdscp = 0;
+
+	/*
+	 * Initialize the lock.
+	 */
+	isc_mutex_init(&sock->lock);
+
+	sock->magic = SOCKET_MAGIC;
+	*socketp = sock;
+
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * This event requires that the various lists be empty, that the reference
+ * count be 1, and that the magic number is valid.  The other socket bits,
+ * like the lock, must be initialized as well.  The fd associated must be
+ * marked as closed, by setting it to -1 on close, or this routine will
+ * also close the socket.
+ */
+static void
+free_socket(isc_socket_t **socketp) {
+	isc_socket_t *sock = *socketp;
+	*socketp = NULL;
+
+	INSIST(VALID_SOCKET(sock));
+	isc_refcount_destroy(&sock->references);
+	LOCK(&sock->lock);
+	INSIST(!sock->connecting);
+	INSIST(ISC_LIST_EMPTY(sock->recv_list));
+	INSIST(ISC_LIST_EMPTY(sock->send_list));
+	INSIST(ISC_LIST_EMPTY(sock->accept_list));
+	INSIST(ISC_LIST_EMPTY(sock->connect_list));
+	INSIST(!ISC_LINK_LINKED(sock, link));
+	UNLOCK(&sock->lock);
+
+	sock->magic = 0;
+
+	isc_mutex_destroy(&sock->lock);
+
+	isc_mem_put(sock->manager->mctx, sock, sizeof(*sock));
+}
+
+#if defined(SET_RCVBUF)
+static isc_once_t rcvbuf_once = ISC_ONCE_INIT;
+static int rcvbuf = ISC_RECV_BUFFER_SIZE;
+
+static void
+set_rcvbuf(void) {
+	int fd;
+	int max = rcvbuf, min;
+	socklen_t len;
+
+	fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+	if (fd == -1) {
+		switch (errno) {
+		case EPROTONOSUPPORT:
+		case EPFNOSUPPORT:
+		case EAFNOSUPPORT:
+		/*
+		 * Linux 2.2 (and maybe others) return EINVAL instead of
+		 * EAFNOSUPPORT.
+		 */
+		case EINVAL:
+			fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+			break;
+		}
+	}
+	if (fd == -1) {
+		return;
+	}
+
+	len = sizeof(min);
+	if (getsockopt(fd, SOL_SOCKET, SO_RCVBUF, (void *)&min, &len) == 0 &&
+	    min < rcvbuf)
+	{
+	again:
+		if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, (void *)&rcvbuf,
+			       sizeof(rcvbuf)) == -1)
+		{
+			if (errno == ENOBUFS && rcvbuf > min) {
+				max = rcvbuf - 1;
+				rcvbuf = (rcvbuf + min) / 2;
+				goto again;
+			} else {
+				rcvbuf = min;
+				goto cleanup;
+			}
+		} else {
+			min = rcvbuf;
+		}
+		if (min != max) {
+			rcvbuf = max;
+			goto again;
+		}
+	}
+cleanup:
+	close(fd);
+}
+#endif /* ifdef SO_RCVBUF */
+
+#if defined(SET_SNDBUF)
+static isc_once_t sndbuf_once = ISC_ONCE_INIT;
+static int sndbuf = ISC_SEND_BUFFER_SIZE;
+
+static void
+set_sndbuf(void) {
+	int fd;
+	int max = sndbuf, min;
+	socklen_t len;
+
+	fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+	if (fd == -1) {
+		switch (errno) {
+		case EPROTONOSUPPORT:
+		case EPFNOSUPPORT:
+		case EAFNOSUPPORT:
+		/*
+		 * Linux 2.2 (and maybe others) return EINVAL instead of
+		 * EAFNOSUPPORT.
+		 */
+		case EINVAL:
+			fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+			break;
+		}
+	}
+	if (fd == -1) {
+		return;
+	}
+
+	len = sizeof(min);
+	if (getsockopt(fd, SOL_SOCKET, SO_SNDBUF, (void *)&min, &len) == 0 &&
+	    min < sndbuf)
+	{
+	again:
+		if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, (void *)&sndbuf,
+			       sizeof(sndbuf)) == -1)
+		{
+			if (errno == ENOBUFS && sndbuf > min) {
+				max = sndbuf - 1;
+				sndbuf = (sndbuf + min) / 2;
+				goto again;
+			} else {
+				sndbuf = min;
+				goto cleanup;
+			}
+		} else {
+			min = sndbuf;
+		}
+		if (min != max) {
+			sndbuf = max;
+			goto again;
+		}
+	}
+cleanup:
+	close(fd);
+}
+#endif /* ifdef SO_SNDBUF */
+
+static void
+use_min_mtu(isc_socket_t *sock) {
+#if !defined(IPV6_USE_MIN_MTU) && !defined(IPV6_MTU)
+	UNUSED(sock);
+#endif /* if !defined(IPV6_USE_MIN_MTU) && !defined(IPV6_MTU) */
+#ifdef IPV6_USE_MIN_MTU
+	/* use minimum MTU */
+	if (sock->pf == AF_INET6) {
+		int on = 1;
+		(void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_USE_MIN_MTU,
+				 (void *)&on, sizeof(on));
+	}
+#endif /* ifdef IPV6_USE_MIN_MTU */
+#if defined(IPV6_MTU)
+	/*
+	 * Use minimum MTU on IPv6 sockets.
+	 */
+	if (sock->pf == AF_INET6) {
+		int mtu = 1280;
+		(void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_MTU, &mtu,
+				 sizeof(mtu));
+	}
+#endif /* if defined(IPV6_MTU) */
+}
+
+static void
+set_tcp_maxseg(isc_socket_t *sock, int size) {
+#ifdef TCP_MAXSEG
+	if (sock->type == isc_sockettype_tcp) {
+		(void)setsockopt(sock->fd, IPPROTO_TCP, TCP_MAXSEG,
+				 (void *)&size, sizeof(size));
+	}
+#endif /* ifdef TCP_MAXSEG */
+}
+
+static void
+set_ip_disable_pmtud(isc_socket_t *sock) {
+	/*
+	 * Disable Path MTU Discover on IP packets
+	 */
+	if (sock->pf == AF_INET6) {
+#if defined(IPV6_DONTFRAG)
+		(void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_DONTFRAG,
+				 &(int){ 0 }, sizeof(int));
+#endif
+#if defined(IPV6_MTU_DISCOVER) && defined(IP_PMTUDISC_OMIT)
+		(void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_MTU_DISCOVER,
+				 &(int){ IP_PMTUDISC_OMIT }, sizeof(int));
+#endif
+	} else if (sock->pf == AF_INET) {
+#if defined(IP_DONTFRAG)
+		(void)setsockopt(sock->fd, IPPROTO_IP, IP_DONTFRAG, &(int){ 0 },
+				 sizeof(int));
+#endif
+#if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_OMIT)
+		(void)setsockopt(sock->fd, IPPROTO_IP, IP_MTU_DISCOVER,
+				 &(int){ IP_PMTUDISC_OMIT }, sizeof(int));
+#endif
+	}
+}
+
+static isc_result_t
+opensocket(isc_socketmgr_t *manager, isc_socket_t *sock,
+	   isc_socket_t *dup_socket) {
+	isc_result_t result;
+	char strbuf[ISC_STRERRORSIZE];
+	const char *err = "socket";
+	int tries = 0;
+#if defined(USE_CMSG) || defined(SO_NOSIGPIPE)
+	int on = 1;
+#endif /* if defined(USE_CMSG) || defined(SO_NOSIGPIPE) */
+#if defined(SET_RCVBUF) || defined(SET_SNDBUF)
+	socklen_t optlen;
+	int size = 0;
+#endif
+
+again:
+	if (dup_socket == NULL) {
+		switch (sock->type) {
+		case isc_sockettype_udp:
+			sock->fd = socket(sock->pf, SOCK_DGRAM, IPPROTO_UDP);
+			break;
+		case isc_sockettype_tcp:
+			sock->fd = socket(sock->pf, SOCK_STREAM, IPPROTO_TCP);
+			break;
+		case isc_sockettype_unix:
+			sock->fd = socket(sock->pf, SOCK_STREAM, 0);
+			break;
+		case isc_sockettype_raw:
+			errno = EPFNOSUPPORT;
+			/*
+			 * PF_ROUTE is a alias for PF_NETLINK on linux.
+			 */
+#if defined(PF_ROUTE)
+			if (sock->fd == -1 && sock->pf == PF_ROUTE) {
+#ifdef NETLINK_ROUTE
+				sock->fd = socket(sock->pf, SOCK_RAW,
+						  NETLINK_ROUTE);
+#else  /* ifdef NETLINK_ROUTE */
+				sock->fd = socket(sock->pf, SOCK_RAW, 0);
+#endif /* ifdef NETLINK_ROUTE */
+				if (sock->fd != -1) {
+#ifdef NETLINK_ROUTE
+					struct sockaddr_nl sa;
+					int n;
+
+					/*
+					 * Do an implicit bind.
+					 */
+					memset(&sa, 0, sizeof(sa));
+					sa.nl_family = AF_NETLINK;
+					sa.nl_groups = RTMGRP_IPV4_IFADDR |
+						       RTMGRP_IPV6_IFADDR;
+					n = bind(sock->fd,
+						 (struct sockaddr *)&sa,
+						 sizeof(sa));
+					if (n < 0) {
+						close(sock->fd);
+						sock->fd = -1;
+					}
+#endif /* ifdef NETLINK_ROUTE */
+					sock->bound = 1;
+				}
+			}
+#endif /* if defined(PF_ROUTE) */
+			break;
+		}
+	} else {
+		sock->fd = dup(dup_socket->fd);
+		sock->dupped = 1;
+		sock->bound = dup_socket->bound;
+	}
+	if (sock->fd == -1 && errno == EINTR && tries++ < 42) {
+		goto again;
+	}
+
+#ifdef F_DUPFD
+	/*
+	 * Leave a space for stdio and TCP to work in.
+	 */
+	if (manager->reserved != 0 && sock->type == isc_sockettype_udp &&
+	    sock->fd >= 0 && sock->fd < manager->reserved)
+	{
+		int newfd, tmp;
+		newfd = fcntl(sock->fd, F_DUPFD, manager->reserved);
+		tmp = errno;
+		(void)close(sock->fd);
+		errno = tmp;
+		sock->fd = newfd;
+		err = "isc_socket_create: fcntl/reserved";
+	} else if (sock->fd >= 0 && sock->fd < 20) {
+		int newfd, tmp;
+		newfd = fcntl(sock->fd, F_DUPFD, 20);
+		tmp = errno;
+		(void)close(sock->fd);
+		errno = tmp;
+		sock->fd = newfd;
+		err = "isc_socket_create: fcntl";
+	}
+#endif /* ifdef F_DUPFD */
+
+	if (sock->fd >= (int)manager->maxsocks) {
+		(void)close(sock->fd);
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+			      "socket: file descriptor exceeds limit (%d/%u)",
+			      sock->fd, manager->maxsocks);
+		inc_stats(manager->stats, sock->statsindex[STATID_OPENFAIL]);
+		return (ISC_R_NORESOURCES);
+	}
+
+	if (sock->fd < 0) {
+		switch (errno) {
+		case EMFILE:
+		case ENFILE:
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+				      "%s: %s", err, strbuf);
+			FALLTHROUGH;
+		case ENOBUFS:
+			inc_stats(manager->stats,
+				  sock->statsindex[STATID_OPENFAIL]);
+			return (ISC_R_NORESOURCES);
+
+		case EPROTONOSUPPORT:
+		case EPFNOSUPPORT:
+		case EAFNOSUPPORT:
+		/*
+		 * Linux 2.2 (and maybe others) return EINVAL instead of
+		 * EAFNOSUPPORT.
+		 */
+		case EINVAL:
+			inc_stats(manager->stats,
+				  sock->statsindex[STATID_OPENFAIL]);
+			return (ISC_R_FAMILYNOSUPPORT);
+
+		default:
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__, "%s() failed: %s",
+					 err, strbuf);
+			inc_stats(manager->stats,
+				  sock->statsindex[STATID_OPENFAIL]);
+			return (ISC_R_UNEXPECTED);
+		}
+	}
+
+	if (dup_socket != NULL) {
+		goto setup_done;
+	}
+
+	result = make_nonblock(sock->fd);
+	if (result != ISC_R_SUCCESS) {
+		(void)close(sock->fd);
+		inc_stats(manager->stats, sock->statsindex[STATID_OPENFAIL]);
+		return (result);
+	}
+
+#ifdef SO_NOSIGPIPE
+	if (setsockopt(sock->fd, SOL_SOCKET, SO_NOSIGPIPE, (void *)&on,
+		       sizeof(on)) < 0)
+	{
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "setsockopt(%d, SO_NOSIGPIPE) failed: %s",
+				 sock->fd, strbuf);
+		/* Press on... */
+	}
+#endif /* ifdef SO_NOSIGPIPE */
+
+	/*
+	 * Use minimum mtu if possible.
+	 */
+	if (sock->type == isc_sockettype_tcp && sock->pf == AF_INET6) {
+		use_min_mtu(sock);
+		set_tcp_maxseg(sock, 1280 - 20 - 40); /* 1280 - TCP - IPV6 */
+	}
+
+#if defined(USE_CMSG) || defined(SET_RCVBUF) || defined(SET_SNDBUF)
+	if (sock->type == isc_sockettype_udp) {
+#if defined(USE_CMSG)
+#if defined(SO_TIMESTAMP)
+		if (setsockopt(sock->fd, SOL_SOCKET, SO_TIMESTAMP, (void *)&on,
+			       sizeof(on)) < 0 &&
+		    errno != ENOPROTOOPT)
+		{
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, SO_TIMESTAMP) failed: "
+					 "%s",
+					 sock->fd, strbuf);
+			/* Press on... */
+		}
+#endif /* SO_TIMESTAMP */
+
+#ifdef IPV6_RECVPKTINFO
+		/* RFC 3542 */
+		if ((sock->pf == AF_INET6) &&
+		    (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
+				(void *)&on, sizeof(on)) < 0))
+		{
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, IPV6_RECVPKTINFO) "
+					 "failed: %s",
+					 sock->fd, strbuf);
+		}
+#else  /* ifdef IPV6_RECVPKTINFO */
+		/* RFC 2292 */
+		if ((sock->pf == AF_INET6) &&
+		    (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_PKTINFO,
+				(void *)&on, sizeof(on)) < 0))
+		{
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, IPV6_PKTINFO) failed: "
+					 "%s",
+					 sock->fd, strbuf);
+		}
+#endif /* IPV6_RECVPKTINFO */
+#endif /* defined(USE_CMSG) */
+
+#if defined(SET_RCVBUF)
+		optlen = sizeof(size);
+		if (getsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF, (void *)&size,
+			       &optlen) == 0 &&
+		    size < rcvbuf)
+		{
+			RUNTIME_CHECK(isc_once_do(&rcvbuf_once, set_rcvbuf) ==
+				      ISC_R_SUCCESS);
+			if (setsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF,
+				       (void *)&rcvbuf, sizeof(rcvbuf)) == -1)
+			{
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				UNEXPECTED_ERROR(__FILE__, __LINE__,
+						 "setsockopt(%d, SO_RCVBUF, "
+						 "%d) failed: %s",
+						 sock->fd, rcvbuf, strbuf);
+			}
+		}
+#endif /* if defined(SET_RCVBUF) */
+
+#if defined(SET_SNDBUF)
+		optlen = sizeof(size);
+		if (getsockopt(sock->fd, SOL_SOCKET, SO_SNDBUF, (void *)&size,
+			       &optlen) == 0 &&
+		    size < sndbuf)
+		{
+			RUNTIME_CHECK(isc_once_do(&sndbuf_once, set_sndbuf) ==
+				      ISC_R_SUCCESS);
+			if (setsockopt(sock->fd, SOL_SOCKET, SO_SNDBUF,
+				       (void *)&sndbuf, sizeof(sndbuf)) == -1)
+			{
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				UNEXPECTED_ERROR(__FILE__, __LINE__,
+						 "setsockopt(%d, SO_SNDBUF, "
+						 "%d) failed: %s",
+						 sock->fd, sndbuf, strbuf);
+			}
+		}
+#endif /* if defined(SO_SNDBUF) */
+	}
+#ifdef IPV6_RECVTCLASS
+	if ((sock->pf == AF_INET6) &&
+	    (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_RECVTCLASS, (void *)&on,
+			sizeof(on)) < 0))
+	{
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "setsockopt(%d, IPV6_RECVTCLASS) "
+				 "failed: %s",
+				 sock->fd, strbuf);
+	}
+#endif /* ifdef IPV6_RECVTCLASS */
+#ifdef IP_RECVTOS
+	if ((sock->pf == AF_INET) &&
+	    (setsockopt(sock->fd, IPPROTO_IP, IP_RECVTOS, (void *)&on,
+			sizeof(on)) < 0))
+	{
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "setsockopt(%d, IP_RECVTOS) "
+				 "failed: %s",
+				 sock->fd, strbuf);
+	}
+#endif /* ifdef IP_RECVTOS */
+#endif /* defined(USE_CMSG) || defined(SET_RCVBUF) || defined(SET_SNDBUF) */
+
+	set_ip_disable_pmtud(sock);
+
+setup_done:
+	inc_stats(manager->stats, sock->statsindex[STATID_OPEN]);
+	if (sock->active == 0) {
+		inc_stats(manager->stats, sock->statsindex[STATID_ACTIVE]);
+		sock->active = 1;
+	}
+
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * Create a 'type' socket or duplicate an existing socket, managed
+ * by 'manager'.  Events will be posted to 'task' and when dispatched
+ * 'action' will be called with 'arg' as the arg value.  The new
+ * socket is returned in 'socketp'.
+ */
+static isc_result_t
+socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
+	      isc_socket_t **socketp, isc_socket_t *dup_socket) {
+	isc_socket_t *sock = NULL;
+	isc__socketthread_t *thread;
+	isc_result_t result;
+	int lockid;
+
+	REQUIRE(VALID_MANAGER(manager));
+	REQUIRE(socketp != NULL && *socketp == NULL);
+
+	result = allocate_socket(manager, type, &sock);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+
+	switch (sock->type) {
+	case isc_sockettype_udp:
+		sock->statsindex = (pf == AF_INET) ? udp4statsindex
+						   : udp6statsindex;
+#define DCSPPKT(pf) ((pf == AF_INET) ? ISC_NET_DSCPPKTV4 : ISC_NET_DSCPPKTV6)
+		sock->pktdscp = (isc_net_probedscp() & DCSPPKT(pf)) != 0;
+		break;
+	case isc_sockettype_tcp:
+		sock->statsindex = (pf == AF_INET) ? tcp4statsindex
+						   : tcp6statsindex;
+		break;
+	case isc_sockettype_unix:
+		sock->statsindex = unixstatsindex;
+		break;
+	case isc_sockettype_raw:
+		sock->statsindex = rawstatsindex;
+		break;
+	default:
+		UNREACHABLE();
+	}
+
+	sock->pf = pf;
+
+	result = opensocket(manager, sock, dup_socket);
+	if (result != ISC_R_SUCCESS) {
+		free_socket(&sock);
+		return (result);
+	}
+
+	if (sock->fd == -1) {
+		abort();
+	}
+	sock->threadid = gen_threadid(sock);
+	isc_refcount_increment0(&sock->references);
+	thread = &manager->threads[sock->threadid];
+	*socketp = sock;
+
+	/*
+	 * Note we don't have to lock the socket like we normally would because
+	 * there are no external references to it yet.
+	 */
+
+	lockid = FDLOCK_ID(sock->fd);
+	LOCK(&thread->fdlock[lockid]);
+	thread->fds[sock->fd] = sock;
+	thread->fdstate[sock->fd] = MANAGED;
+#if defined(USE_EPOLL)
+	thread->epoll_events[sock->fd] = 0;
+#endif /* if defined(USE_EPOLL) */
+#ifdef USE_DEVPOLL
+	INSIST(thread->fdpollinfo[sock->fd].want_read == 0 &&
+	       thread->fdpollinfo[sock->fd].want_write == 0);
+#endif /* ifdef USE_DEVPOLL */
+	UNLOCK(&thread->fdlock[lockid]);
+
+	LOCK(&manager->lock);
+	ISC_LIST_APPEND(manager->socklist, sock, link);
+#ifdef USE_SELECT
+	if (thread->maxfd < sock->fd) {
+		thread->maxfd = sock->fd;
+	}
+#endif /* ifdef USE_SELECT */
+	UNLOCK(&manager->lock);
+
+	socket_log(sock, NULL, CREATION,
+		   dup_socket != NULL ? "dupped" : "created");
+
+	return (ISC_R_SUCCESS);
+}
+
+/*%
+ * Create a new 'type' socket managed by 'manager'.  Events
+ * will be posted to 'task' and when dispatched 'action' will be
+ * called with 'arg' as the arg value.  The new socket is returned
+ * in 'socketp'.
+ */
+isc_result_t
+isc_socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
+		  isc_socket_t **socketp) {
+	return (socket_create(manager0, pf, type, socketp, NULL));
+}
+
+/*%
+ * Duplicate an existing socket.  The new socket is returned
+ * in 'socketp'.
+ */
+isc_result_t
+isc_socket_dup(isc_socket_t *sock, isc_socket_t **socketp) {
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(socketp != NULL && *socketp == NULL);
+
+	return (socket_create(sock->manager, sock->pf, sock->type, socketp,
+			      sock));
+}
+
+isc_result_t
+isc_socket_open(isc_socket_t *sock) {
+	isc_result_t result;
+	isc__socketthread_t *thread;
+
+	REQUIRE(VALID_SOCKET(sock));
+
+	LOCK(&sock->lock);
+
+	REQUIRE(isc_refcount_current(&sock->references) >= 1);
+	REQUIRE(sock->fd == -1);
+	REQUIRE(sock->threadid == -1);
+
+	result = opensocket(sock->manager, sock, NULL);
+
+	UNLOCK(&sock->lock);
+
+	if (result != ISC_R_SUCCESS) {
+		sock->fd = -1;
+	} else {
+		sock->threadid = gen_threadid(sock);
+		thread = &sock->manager->threads[sock->threadid];
+		int lockid = FDLOCK_ID(sock->fd);
+
+		LOCK(&thread->fdlock[lockid]);
+		thread->fds[sock->fd] = sock;
+		thread->fdstate[sock->fd] = MANAGED;
+#if defined(USE_EPOLL)
+		thread->epoll_events[sock->fd] = 0;
+#endif /* if defined(USE_EPOLL) */
+#ifdef USE_DEVPOLL
+		INSIST(thread->fdpollinfo[sock->fd].want_read == 0 &&
+		       thread->fdpollinfo[sock->fd].want_write == 0);
+#endif /* ifdef USE_DEVPOLL */
+		UNLOCK(&thread->fdlock[lockid]);
+
+#ifdef USE_SELECT
+		LOCK(&sock->manager->lock);
+		if (thread->maxfd < sock->fd) {
+			thread->maxfd = sock->fd;
+		}
+		UNLOCK(&sock->manager->lock);
+#endif /* ifdef USE_SELECT */
+	}
+
+	return (result);
+}
+
+/*
+ * Attach to a socket.  Caller must explicitly detach when it is done.
+ */
+void
+isc_socket_attach(isc_socket_t *sock, isc_socket_t **socketp) {
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(socketp != NULL && *socketp == NULL);
+
+	int old_refs = isc_refcount_increment(&sock->references);
+	REQUIRE(old_refs > 0);
+
+	*socketp = sock;
+}
+
+/*
+ * Dereference a socket.  If this is the last reference to it, clean things
+ * up by destroying the socket.
+ */
+void
+isc_socket_detach(isc_socket_t **socketp) {
+	isc_socket_t *sock;
+
+	REQUIRE(socketp != NULL);
+	sock = *socketp;
+	REQUIRE(VALID_SOCKET(sock));
+	if (isc_refcount_decrement(&sock->references) == 1) {
+		destroy(&sock);
+	}
+
+	*socketp = NULL;
+}
+
+isc_result_t
+isc_socket_close(isc_socket_t *sock) {
+	int fd;
+	isc_socketmgr_t *manager;
+	isc__socketthread_t *thread;
+	fflush(stdout);
+	REQUIRE(VALID_SOCKET(sock));
+
+	LOCK(&sock->lock);
+
+	REQUIRE(sock->fd >= 0 && sock->fd < (int)sock->manager->maxsocks);
+
+	INSIST(!sock->connecting);
+	INSIST(ISC_LIST_EMPTY(sock->recv_list));
+	INSIST(ISC_LIST_EMPTY(sock->send_list));
+	INSIST(ISC_LIST_EMPTY(sock->accept_list));
+	INSIST(ISC_LIST_EMPTY(sock->connect_list));
+
+	manager = sock->manager;
+	thread = &manager->threads[sock->threadid];
+	fd = sock->fd;
+	sock->fd = -1;
+	sock->threadid = -1;
+
+	sock->dupped = 0;
+	memset(sock->name, 0, sizeof(sock->name));
+	sock->tag = NULL;
+	sock->listener = 0;
+	sock->connected = 0;
+	sock->connecting = 0;
+	sock->bound = 0;
+	isc_sockaddr_any(&sock->peer_address);
+
+	UNLOCK(&sock->lock);
+
+	socketclose(thread, sock, fd);
+
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * Dequeue an item off the given socket's read queue, set the result code
+ * in the done event to the one provided, and send it to the task it was
+ * destined for.
+ *
+ * If the event to be sent is on a list, remove it before sending.  If
+ * asked to, send and detach from the socket as well.
+ *
+ * Caller must have the socket locked if the event is attached to the socket.
+ */
+static void
+send_recvdone_event(isc_socket_t *sock, isc_socketevent_t **dev) {
+	isc_task_t *task;
+
+	task = (*dev)->ev_sender;
+
+	(*dev)->ev_sender = sock;
+
+	if (ISC_LINK_LINKED(*dev, ev_link)) {
+		ISC_LIST_DEQUEUE(sock->recv_list, *dev, ev_link);
+	}
+
+	if (((*dev)->attributes & ISC_SOCKEVENTATTR_ATTACHED) != 0) {
+		isc_task_sendtoanddetach(&task, (isc_event_t **)dev,
+					 sock->threadid);
+	} else {
+		isc_task_sendto(task, (isc_event_t **)dev, sock->threadid);
+	}
+}
+
+/*
+ * See comments for send_recvdone_event() above.
+ *
+ * Caller must have the socket locked if the event is attached to the socket.
+ */
+static void
+send_senddone_event(isc_socket_t *sock, isc_socketevent_t **dev) {
+	isc_task_t *task;
+
+	INSIST(dev != NULL && *dev != NULL);
+
+	task = (*dev)->ev_sender;
+	(*dev)->ev_sender = sock;
+
+	if (ISC_LINK_LINKED(*dev, ev_link)) {
+		ISC_LIST_DEQUEUE(sock->send_list, *dev, ev_link);
+	}
+
+	if (((*dev)->attributes & ISC_SOCKEVENTATTR_ATTACHED) != 0) {
+		isc_task_sendtoanddetach(&task, (isc_event_t **)dev,
+					 sock->threadid);
+	} else {
+		isc_task_sendto(task, (isc_event_t **)dev, sock->threadid);
+	}
+}
+
+/*
+ * See comments for send_recvdone_event() above.
+ *
+ * Caller must have the socket locked if the event is attached to the socket.
+ */
+static void
+send_connectdone_event(isc_socket_t *sock, isc_socket_connev_t **dev) {
+	isc_task_t *task;
+
+	INSIST(dev != NULL && *dev != NULL);
+
+	task = (*dev)->ev_sender;
+	(*dev)->ev_sender = sock;
+
+	if (ISC_LINK_LINKED(*dev, ev_link)) {
+		ISC_LIST_DEQUEUE(sock->connect_list, *dev, ev_link);
+	}
+
+	isc_task_sendtoanddetach(&task, (isc_event_t **)dev, sock->threadid);
+}
+
+/*
+ * Call accept() on a socket, to get the new file descriptor.  The listen
+ * socket is used as a prototype to create a new isc_socket_t.  The new
+ * socket has one outstanding reference.  The task receiving the event
+ * will be detached from just after the event is delivered.
+ *
+ * On entry to this function, the event delivered is the internal
+ * readable event, and the first item on the accept_list should be
+ * the done event we want to send.  If the list is empty, this is a no-op,
+ * so just unlock and return.
+ */
+static void
+internal_accept(isc_socket_t *sock) {
+	isc_socketmgr_t *manager;
+	isc__socketthread_t *thread, *nthread;
+	isc_socket_newconnev_t *dev;
+	isc_task_t *task;
+	socklen_t addrlen;
+	int fd;
+	isc_result_t result = ISC_R_SUCCESS;
+	char strbuf[ISC_STRERRORSIZE];
+	const char *err = "accept";
+
+	INSIST(VALID_SOCKET(sock));
+	REQUIRE(sock->fd >= 0);
+
+	socket_log(sock, NULL, TRACE, "internal_accept called, locked socket");
+
+	manager = sock->manager;
+	INSIST(VALID_MANAGER(manager));
+	thread = &manager->threads[sock->threadid];
+
+	INSIST(sock->listener);
+
+	/*
+	 * Get the first item off the accept list.
+	 * If it is empty, unlock the socket and return.
+	 */
+	dev = ISC_LIST_HEAD(sock->accept_list);
+	if (dev == NULL) {
+		unwatch_fd(thread, sock->fd, SELECT_POKE_ACCEPT);
+		UNLOCK(&sock->lock);
+		return;
+	}
+
+	/*
+	 * Try to accept the new connection.  If the accept fails with
+	 * EAGAIN or EINTR, simply poke the watcher to watch this socket
+	 * again.  Also ignore ECONNRESET, which has been reported to
+	 * be spuriously returned on Linux 2.2.19 although it is not
+	 * a documented error for accept().  ECONNABORTED has been
+	 * reported for Solaris 8.  The rest are thrown in not because
+	 * we have seen them but because they are ignored by other
+	 * daemons such as BIND 8 and Apache.
+	 */
+
+	addrlen = sizeof(NEWCONNSOCK(dev)->peer_address.type);
+	memset(&NEWCONNSOCK(dev)->peer_address.type, 0, addrlen);
+	fd = accept(sock->fd, &NEWCONNSOCK(dev)->peer_address.type.sa,
+		    (void *)&addrlen);
+
+#ifdef F_DUPFD
+	/*
+	 * Leave a space for stdio to work in.
+	 */
+	if (fd >= 0 && fd < 20) {
+		int newfd, tmp;
+		newfd = fcntl(fd, F_DUPFD, 20);
+		tmp = errno;
+		(void)close(fd);
+		errno = tmp;
+		fd = newfd;
+		err = "accept/fcntl";
+	}
+#endif /* ifdef F_DUPFD */
+
+	if (fd < 0) {
+		if (SOFT_ERROR(errno)) {
+			goto soft_error;
+		}
+		switch (errno) {
+		case ENFILE:
+		case EMFILE:
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+				      "%s: too many open file descriptors",
+				      err);
+			goto soft_error;
+
+		case ENOBUFS:
+		case ENOMEM:
+		case ECONNRESET:
+		case ECONNABORTED:
+		case EHOSTUNREACH:
+		case EHOSTDOWN:
+		case ENETUNREACH:
+		case ENETDOWN:
+		case ECONNREFUSED:
+#ifdef EPROTO
+		case EPROTO:
+#endif /* ifdef EPROTO */
+#ifdef ENONET
+		case ENONET:
+#endif /* ifdef ENONET */
+			goto soft_error;
+		default:
+			break;
+		}
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "internal_accept: %s() failed: %s", err,
+				 strbuf);
+		fd = -1;
+		result = ISC_R_UNEXPECTED;
+	} else {
+		if (addrlen == 0U) {
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "internal_accept(): "
+					 "accept() failed to return "
+					 "remote address");
+
+			(void)close(fd);
+			goto soft_error;
+		} else if (NEWCONNSOCK(dev)->peer_address.type.sa.sa_family !=
+			   sock->pf)
+		{
+			UNEXPECTED_ERROR(
+				__FILE__, __LINE__,
+				"internal_accept(): "
+				"accept() returned peer address "
+				"family %u (expected %u)",
+				NEWCONNSOCK(dev)->peer_address.type.sa.sa_family,
+				sock->pf);
+			(void)close(fd);
+			goto soft_error;
+		} else if (fd >= (int)manager->maxsocks) {
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+				      "accept: file descriptor exceeds limit "
+				      "(%d/%u)",
+				      fd, manager->maxsocks);
+			(void)close(fd);
+			goto soft_error;
+		}
+	}
+
+	if (fd != -1) {
+		NEWCONNSOCK(dev)->peer_address.length = addrlen;
+		NEWCONNSOCK(dev)->pf = sock->pf;
+	}
+
+	/*
+	 * Pull off the done event.
+	 */
+	ISC_LIST_UNLINK(sock->accept_list, dev, ev_link);
+
+	/*
+	 * Poke watcher if there are more pending accepts.
+	 */
+	if (ISC_LIST_EMPTY(sock->accept_list)) {
+		unwatch_fd(thread, sock->fd, SELECT_POKE_ACCEPT);
+	}
+
+	if (fd != -1) {
+		result = make_nonblock(fd);
+		if (result != ISC_R_SUCCESS) {
+			(void)close(fd);
+			fd = -1;
+		}
+	}
+
+	/*
+	 * We need to unlock sock->lock now to be able to lock manager->lock
+	 * without risking a deadlock with xmlstats.
+	 */
+	UNLOCK(&sock->lock);
+
+	/*
+	 * -1 means the new socket didn't happen.
+	 */
+	if (fd != -1) {
+		int lockid = FDLOCK_ID(fd);
+
+		NEWCONNSOCK(dev)->fd = fd;
+		NEWCONNSOCK(dev)->threadid = gen_threadid(NEWCONNSOCK(dev));
+		NEWCONNSOCK(dev)->bound = 1;
+		NEWCONNSOCK(dev)->connected = 1;
+		nthread = &manager->threads[NEWCONNSOCK(dev)->threadid];
+
+		/*
+		 * We already hold a lock on one fdlock in accepting thread,
+		 * we need to make sure that we don't double lock.
+		 */
+		bool same_bucket = (sock->threadid ==
+				    NEWCONNSOCK(dev)->threadid) &&
+				   (FDLOCK_ID(sock->fd) == lockid);
+
+		/*
+		 * Use minimum mtu if possible.
+		 */
+		use_min_mtu(NEWCONNSOCK(dev));
+		set_tcp_maxseg(NEWCONNSOCK(dev), 1280 - 20 - 40);
+
+		/*
+		 * Ensure DSCP settings are inherited across accept.
+		 */
+		setdscp(NEWCONNSOCK(dev), sock->dscp);
+
+		/*
+		 * Save away the remote address
+		 */
+		dev->address = NEWCONNSOCK(dev)->peer_address;
+
+		if (NEWCONNSOCK(dev)->active == 0) {
+			inc_stats(manager->stats,
+				  NEWCONNSOCK(dev)->statsindex[STATID_ACTIVE]);
+			NEWCONNSOCK(dev)->active = 1;
+		}
+
+		if (!same_bucket) {
+			LOCK(&nthread->fdlock[lockid]);
+		}
+		nthread->fds[fd] = NEWCONNSOCK(dev);
+		nthread->fdstate[fd] = MANAGED;
+#if defined(USE_EPOLL)
+		nthread->epoll_events[fd] = 0;
+#endif /* if defined(USE_EPOLL) */
+		if (!same_bucket) {
+			UNLOCK(&nthread->fdlock[lockid]);
+		}
+
+		LOCK(&manager->lock);
+
+#ifdef USE_SELECT
+		if (nthread->maxfd < fd) {
+			nthread->maxfd = fd;
+		}
+#endif /* ifdef USE_SELECT */
+
+		socket_log(sock, &NEWCONNSOCK(dev)->peer_address, CREATION,
+			   "accepted connection, new socket %p",
+			   dev->newsocket);
+
+		ISC_LIST_APPEND(manager->socklist, NEWCONNSOCK(dev), link);
+
+		UNLOCK(&manager->lock);
+
+		inc_stats(manager->stats, sock->statsindex[STATID_ACCEPT]);
+	} else {
+		inc_stats(manager->stats, sock->statsindex[STATID_ACCEPTFAIL]);
+		isc_refcount_decrementz(&NEWCONNSOCK(dev)->references);
+		free_socket((isc_socket_t **)&dev->newsocket);
+	}
+
+	/*
+	 * Fill in the done event details and send it off.
+	 */
+	dev->result = result;
+	task = dev->ev_sender;
+	dev->ev_sender = sock;
+
+	isc_task_sendtoanddetach(&task, ISC_EVENT_PTR(&dev), sock->threadid);
+	return;
+
+soft_error:
+	watch_fd(thread, sock->fd, SELECT_POKE_ACCEPT);
+	UNLOCK(&sock->lock);
+
+	inc_stats(manager->stats, sock->statsindex[STATID_ACCEPTFAIL]);
+	return;
+}
+
+static void
+internal_recv(isc_socket_t *sock) {
+	isc_socketevent_t *dev;
+
+	INSIST(VALID_SOCKET(sock));
+	REQUIRE(sock->fd >= 0);
+
+	dev = ISC_LIST_HEAD(sock->recv_list);
+	if (dev == NULL) {
+		goto finish;
+	}
+
+	socket_log(sock, NULL, IOEVENT, "internal_recv: event %p -> task %p",
+		   dev, dev->ev_sender);
+
+	/*
+	 * Try to do as much I/O as possible on this socket.  There are no
+	 * limits here, currently.
+	 */
+	while (dev != NULL) {
+		switch (doio_recv(sock, dev)) {
+		case DOIO_SOFT:
+			goto finish;
+
+		case DOIO_EOF:
+			/*
+			 * read of 0 means the remote end was closed.
+			 * Run through the event queue and dispatch all
+			 * the events with an EOF result code.
+			 */
+			do {
+				dev->result = ISC_R_EOF;
+				send_recvdone_event(sock, &dev);
+				dev = ISC_LIST_HEAD(sock->recv_list);
+			} while (dev != NULL);
+			goto finish;
+
+		case DOIO_SUCCESS:
+		case DOIO_HARD:
+			send_recvdone_event(sock, &dev);
+			break;
+		}
+
+		dev = ISC_LIST_HEAD(sock->recv_list);
+	}
+
+finish:
+	if (ISC_LIST_EMPTY(sock->recv_list)) {
+		unwatch_fd(&sock->manager->threads[sock->threadid], sock->fd,
+			   SELECT_POKE_READ);
+	}
+}
+
+static void
+internal_send(isc_socket_t *sock) {
+	isc_socketevent_t *dev;
+
+	INSIST(VALID_SOCKET(sock));
+	REQUIRE(sock->fd >= 0);
+
+	dev = ISC_LIST_HEAD(sock->send_list);
+	if (dev == NULL) {
+		goto finish;
+	}
+	socket_log(sock, NULL, EVENT, "internal_send: event %p -> task %p", dev,
+		   dev->ev_sender);
+
+	/*
+	 * Try to do as much I/O as possible on this socket.  There are no
+	 * limits here, currently.
+	 */
+	while (dev != NULL) {
+		switch (doio_send(sock, dev)) {
+		case DOIO_SOFT:
+			goto finish;
+
+		case DOIO_HARD:
+		case DOIO_SUCCESS:
+			send_senddone_event(sock, &dev);
+			break;
+		}
+
+		dev = ISC_LIST_HEAD(sock->send_list);
+	}
+
+finish:
+	if (ISC_LIST_EMPTY(sock->send_list)) {
+		unwatch_fd(&sock->manager->threads[sock->threadid], sock->fd,
+			   SELECT_POKE_WRITE);
+	}
+}
+
+/*
+ * Process read/writes on each fd here.  Avoid locking
+ * and unlocking twice if both reads and writes are possible.
+ */
+static void
+process_fd(isc__socketthread_t *thread, int fd, bool readable, bool writeable) {
+	isc_socket_t *sock;
+	int lockid = FDLOCK_ID(fd);
+
+	/*
+	 * If the socket is going to be closed, don't do more I/O.
+	 */
+	LOCK(&thread->fdlock[lockid]);
+	if (thread->fdstate[fd] == CLOSE_PENDING) {
+		UNLOCK(&thread->fdlock[lockid]);
+
+		(void)unwatch_fd(thread, fd, SELECT_POKE_READ);
+		(void)unwatch_fd(thread, fd, SELECT_POKE_WRITE);
+		return;
+	}
+
+	sock = thread->fds[fd];
+	if (sock == NULL) {
+		UNLOCK(&thread->fdlock[lockid]);
+		return;
+	}
+
+	LOCK(&sock->lock);
+
+	if (sock->fd < 0) {
+		/*
+		 * Sock is being closed - the final external reference
+		 * is gone but it was not yet removed from event loop
+		 * and fdstate[]/fds[] as destroy() is waiting on
+		 * thread->fdlock[lockid] or sock->lock that we're holding.
+		 * Just release the locks and bail.
+		 */
+		UNLOCK(&sock->lock);
+		UNLOCK(&thread->fdlock[lockid]);
+		return;
+	}
+
+	REQUIRE(readable || writeable);
+	if (writeable) {
+		if (sock->connecting) {
+			internal_connect(sock);
+		} else {
+			internal_send(sock);
+		}
+	}
+
+	if (readable) {
+		if (sock->listener) {
+			internal_accept(sock); /* unlocks sock */
+		} else {
+			internal_recv(sock);
+			UNLOCK(&sock->lock);
+		}
+	} else {
+		UNLOCK(&sock->lock);
+	}
+
+	UNLOCK(&thread->fdlock[lockid]);
+
+	/*
+	 * Socket destruction might be pending, it will resume
+	 * after releasing fdlock and sock->lock.
+	 */
+}
+
+/*
+ * process_fds is different for different event loops
+ * it takes the events from event loops and for each FD
+ * launches process_fd
+ */
+#ifdef USE_KQUEUE
+static bool
+process_fds(isc__socketthread_t *thread, struct kevent *events, int nevents) {
+	int i;
+	bool readable, writable;
+	bool done = false;
+	bool have_ctlevent = false;
+	if (nevents == thread->nevents) {
+		/*
+		 * This is not an error, but something unexpected.  If this
+		 * happens, it may indicate the need for increasing
+		 * ISC_SOCKET_MAXEVENTS.
+		 */
+		thread_log(thread, ISC_LOGCATEGORY_GENERAL,
+			   ISC_LOGMODULE_SOCKET, ISC_LOG_INFO,
+			   "maximum number of FD events (%d) received",
+			   nevents);
+	}
+
+	for (i = 0; i < nevents; i++) {
+		REQUIRE(events[i].ident < thread->manager->maxsocks);
+		if (events[i].ident == (uintptr_t)thread->pipe_fds[0]) {
+			have_ctlevent = true;
+			continue;
+		}
+		readable = (events[i].filter == EVFILT_READ);
+		writable = (events[i].filter == EVFILT_WRITE);
+		process_fd(thread, events[i].ident, readable, writable);
+	}
+
+	if (have_ctlevent) {
+		done = process_ctlfd(thread);
+	}
+
+	return (done);
+}
+#elif defined(USE_EPOLL)
+static bool
+process_fds(isc__socketthread_t *thread, struct epoll_event *events,
+	    int nevents) {
+	int i;
+	bool done = false;
+	bool have_ctlevent = false;
+
+	if (nevents == thread->nevents) {
+		thread_log(thread, ISC_LOGCATEGORY_GENERAL,
+			   ISC_LOGMODULE_SOCKET, ISC_LOG_INFO,
+			   "maximum number of FD events (%d) received",
+			   nevents);
+	}
+
+	for (i = 0; i < nevents; i++) {
+		REQUIRE(events[i].data.fd < (int)thread->manager->maxsocks);
+		if (events[i].data.fd == thread->pipe_fds[0]) {
+			have_ctlevent = true;
+			continue;
+		}
+		if ((events[i].events & EPOLLERR) != 0 ||
+		    (events[i].events & EPOLLHUP) != 0)
+		{
+			/*
+			 * epoll does not set IN/OUT bits on an erroneous
+			 * condition, so we need to try both anyway.  This is a
+			 * bit inefficient, but should be okay for such rare
+			 * events.  Note also that the read or write attempt
+			 * won't block because we use non-blocking sockets.
+			 */
+			int fd = events[i].data.fd;
+			events[i].events |= thread->epoll_events[fd];
+		}
+		process_fd(thread, events[i].data.fd,
+			   (events[i].events & EPOLLIN) != 0,
+			   (events[i].events & EPOLLOUT) != 0);
+	}
+
+	if (have_ctlevent) {
+		done = process_ctlfd(thread);
+	}
+
+	return (done);
+}
+#elif defined(USE_DEVPOLL)
+static bool
+process_fds(isc__socketthread_t *thread, struct pollfd *events, int nevents) {
+	int i;
+	bool done = false;
+	bool have_ctlevent = false;
+
+	if (nevents == thread->nevents) {
+		thread_log(thread, ISC_LOGCATEGORY_GENERAL,
+			   ISC_LOGMODULE_SOCKET, ISC_LOG_INFO,
+			   "maximum number of FD events (%d) received",
+			   nevents);
+	}
+
+	for (i = 0; i < nevents; i++) {
+		REQUIRE(events[i].fd < (int)thread->manager->maxsocks);
+		if (events[i].fd == thread->pipe_fds[0]) {
+			have_ctlevent = true;
+			continue;
+		}
+		process_fd(thread, events[i].fd,
+			   (events[i].events & POLLIN) != 0,
+			   (events[i].events & POLLOUT) != 0);
+	}
+
+	if (have_ctlevent) {
+		done = process_ctlfd(thread);
+	}
+
+	return (done);
+}
+#elif defined(USE_SELECT)
+static void
+process_fds(isc__socketthread_t *thread, int maxfd, fd_set *readfds,
+	    fd_set *writefds) {
+	int i;
+
+	REQUIRE(maxfd <= (int)thread->manager->maxsocks);
+
+	for (i = 0; i < maxfd; i++) {
+		if (i == thread->pipe_fds[0] || i == thread->pipe_fds[1]) {
+			continue;
+		}
+		process_fd(thread, i, FD_ISSET(i, readfds),
+			   FD_ISSET(i, writefds));
+	}
+}
+#endif /* ifdef USE_KQUEUE */
+
+static bool
+process_ctlfd(isc__socketthread_t *thread) {
+	int msg, fd;
+
+	for (;;) {
+		select_readmsg(thread, &fd, &msg);
+
+		thread_log(thread, IOEVENT,
+			   "watcher got message %d for socket %d", msg, fd);
+
+		/*
+		 * Nothing to read?
+		 */
+		if (msg == SELECT_POKE_NOTHING) {
+			break;
+		}
+
+		/*
+		 * Handle shutdown message.  We really should
+		 * jump out of this loop right away, but
+		 * it doesn't matter if we have to do a little
+		 * more work first.
+		 */
+		if (msg == SELECT_POKE_SHUTDOWN) {
+			return (true);
+		}
+
+		/*
+		 * This is a wakeup on a socket.  Look
+		 * at the event queue for both read and write,
+		 * and decide if we need to watch on it now
+		 * or not.
+		 */
+		wakeup_socket(thread, fd, msg);
+	}
+
+	return (false);
+}
+
+/*
+ * This is the thread that will loop forever, always in a select or poll
+ * call.
+ *
+ * When select returns something to do, do whatever's necessary and post
+ * an event to the task that was requesting the action.
+ */
+static isc_threadresult_t
+netthread(void *uap) {
+	isc__socketthread_t *thread = uap;
+	isc_socketmgr_t *manager = thread->manager;
+	(void)manager;
+	bool done;
+	int cc;
+#ifdef USE_KQUEUE
+	const char *fnname = "kevent()";
+#elif defined(USE_EPOLL)
+	const char *fnname = "epoll_wait()";
+#elif defined(USE_DEVPOLL)
+	isc_result_t result;
+	const char *fnname = "ioctl(DP_POLL)";
+	struct dvpoll dvp;
+	int pass;
+#if defined(ISC_SOCKET_USE_POLLWATCH)
+	pollstate_t pollstate = poll_idle;
+#endif /* if defined(ISC_SOCKET_USE_POLLWATCH) */
+#elif defined(USE_SELECT)
+	const char *fnname = "select()";
+	int maxfd;
+	int ctlfd;
+#endif /* ifdef USE_KQUEUE */
+	char strbuf[ISC_STRERRORSIZE];
+
+#if defined(USE_SELECT)
+	/*
+	 * Get the control fd here.  This will never change.
+	 */
+	ctlfd = thread->pipe_fds[0];
+#endif /* if defined(USE_SELECT) */
+	done = false;
+	while (!done) {
+		do {
+#ifdef USE_KQUEUE
+			cc = kevent(thread->kqueue_fd, NULL, 0, thread->events,
+				    thread->nevents, NULL);
+#elif defined(USE_EPOLL)
+			cc = epoll_wait(thread->epoll_fd, thread->events,
+					thread->nevents, -1);
+#elif defined(USE_DEVPOLL)
+			/*
+			 * Re-probe every thousand calls.
+			 */
+			if (thread->calls++ > 1000U) {
+				result = isc_resource_getcurlimit(
+					isc_resource_openfiles,
+					&thread->open_max);
+				if (result != ISC_R_SUCCESS) {
+					thread->open_max = 64;
+				}
+				thread->calls = 0;
+			}
+			for (pass = 0; pass < 2; pass++) {
+				dvp.dp_fds = thread->events;
+				dvp.dp_nfds = thread->nevents;
+				if (dvp.dp_nfds >= thread->open_max) {
+					dvp.dp_nfds = thread->open_max - 1;
+				}
+#ifndef ISC_SOCKET_USE_POLLWATCH
+				dvp.dp_timeout = -1;
+#else  /* ifndef ISC_SOCKET_USE_POLLWATCH */
+				if (pollstate == poll_idle) {
+					dvp.dp_timeout = -1;
+				} else {
+					dvp.dp_timeout =
+						ISC_SOCKET_POLLWATCH_TIMEOUT;
+				}
+#endif /* ISC_SOCKET_USE_POLLWATCH */
+				cc = ioctl(thread->devpoll_fd, DP_POLL, &dvp);
+				if (cc == -1 && errno == EINVAL) {
+					/*
+					 * {OPEN_MAX} may have dropped.  Look
+					 * up the current value and try again.
+					 */
+					result = isc_resource_getcurlimit(
+						isc_resource_openfiles,
+						&thread->open_max);
+					if (result != ISC_R_SUCCESS) {
+						thread->open_max = 64;
+					}
+				} else {
+					break;
+				}
+			}
+#elif defined(USE_SELECT)
+			/*
+			 * We will have only one thread anyway, we can lock
+			 * manager lock and don't care
+			 */
+			LOCK(&manager->lock);
+			memmove(thread->read_fds_copy, thread->read_fds,
+				thread->fd_bufsize);
+			memmove(thread->write_fds_copy, thread->write_fds,
+				thread->fd_bufsize);
+			maxfd = thread->maxfd + 1;
+			UNLOCK(&manager->lock);
+
+			cc = select(maxfd, thread->read_fds_copy,
+				    thread->write_fds_copy, NULL, NULL);
+#endif /* USE_KQUEUE */
+
+			if (cc < 0 && !SOFT_ERROR(errno)) {
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				FATAL_ERROR(__FILE__, __LINE__, "%s failed: %s",
+					    fnname, strbuf);
+			}
+
+#if defined(USE_DEVPOLL) && defined(ISC_SOCKET_USE_POLLWATCH)
+			if (cc == 0) {
+				if (pollstate == poll_active) {
+					pollstate = poll_checking;
+				} else if (pollstate == poll_checking) {
+					pollstate = poll_idle;
+				}
+			} else if (cc > 0) {
+				if (pollstate == poll_checking) {
+					/*
+					 * XXX: We'd like to use a more
+					 * verbose log level as it's actually an
+					 * unexpected event, but the kernel bug
+					 * reportedly happens pretty frequently
+					 * (and it can also be a false positive)
+					 * so it would be just too noisy.
+					 */
+					thread_log(thread,
+						   ISC_LOGCATEGORY_GENERAL,
+						   ISC_LOGMODULE_SOCKET,
+						   ISC_LOG_DEBUG(1),
+						   "unexpected POLL timeout");
+				}
+				pollstate = poll_active;
+			}
+#endif /* if defined(USE_DEVPOLL) && defined(ISC_SOCKET_USE_POLLWATCH) */
+		} while (cc < 0);
+
+#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
+		done = process_fds(thread, thread->events, cc);
+#elif defined(USE_SELECT)
+		process_fds(thread, maxfd, thread->read_fds_copy,
+			    thread->write_fds_copy);
+
+		/*
+		 * Process reads on internal, control fd.
+		 */
+		if (FD_ISSET(ctlfd, thread->read_fds_copy)) {
+			done = process_ctlfd(thread);
+		}
+#endif /* if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL) \
+	* */
+	}
+
+	thread_log(thread, TRACE, "watcher exiting");
+	return ((isc_threadresult_t)0);
+}
+
+void
+isc_socketmgr_setreserved(isc_socketmgr_t *manager, uint32_t reserved) {
+	REQUIRE(VALID_MANAGER(manager));
+
+	manager->reserved = reserved;
+}
+
+void
+isc_socketmgr_maxudp(isc_socketmgr_t *manager, unsigned int maxudp) {
+	REQUIRE(VALID_MANAGER(manager));
+
+	manager->maxudp = maxudp;
+}
+
+/*
+ * Setup socket thread, thread->manager and thread->threadid must be filled.
+ */
+
+static isc_result_t
+setup_thread(isc__socketthread_t *thread) {
+	isc_result_t result = ISC_R_SUCCESS;
+	int i;
+	char strbuf[ISC_STRERRORSIZE];
+
+	REQUIRE(thread != NULL);
+	REQUIRE(VALID_MANAGER(thread->manager));
+	REQUIRE(thread->threadid >= 0 &&
+		thread->threadid < thread->manager->nthreads);
+
+	thread->fds =
+		isc_mem_get(thread->manager->mctx,
+			    thread->manager->maxsocks * sizeof(isc_socket_t *));
+
+	memset(thread->fds, 0,
+	       thread->manager->maxsocks * sizeof(isc_socket_t *));
+
+	thread->fdstate = isc_mem_get(thread->manager->mctx,
+				      thread->manager->maxsocks * sizeof(int));
+
+	memset(thread->fdstate, 0, thread->manager->maxsocks * sizeof(int));
+
+	thread->fdlock = isc_mem_get(thread->manager->mctx,
+				     FDLOCK_COUNT * sizeof(isc_mutex_t));
+
+	for (i = 0; i < FDLOCK_COUNT; i++) {
+		isc_mutex_init(&thread->fdlock[i]);
+	}
+
+	if (pipe(thread->pipe_fds) != 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "pipe() failed: %s",
+				 strbuf);
+		return (ISC_R_UNEXPECTED);
+	}
+	RUNTIME_CHECK(make_nonblock(thread->pipe_fds[0]) == ISC_R_SUCCESS);
+
+#ifdef USE_KQUEUE
+	thread->nevents = ISC_SOCKET_MAXEVENTS;
+	thread->events = isc_mem_get(thread->manager->mctx,
+				     sizeof(struct kevent) * thread->nevents);
+
+	thread->kqueue_fd = kqueue();
+	if (thread->kqueue_fd == -1) {
+		result = isc__errno2result(errno);
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "kqueue failed: %s",
+				 strbuf);
+		isc_mem_put(thread->manager->mctx, thread->events,
+			    sizeof(struct kevent) * thread->nevents);
+		return (result);
+	}
+
+	result = watch_fd(thread, thread->pipe_fds[0], SELECT_POKE_READ);
+	if (result != ISC_R_SUCCESS) {
+		close(thread->kqueue_fd);
+		isc_mem_put(thread->manager->mctx, thread->events,
+			    sizeof(struct kevent) * thread->nevents);
+	}
+	return (result);
+
+#elif defined(USE_EPOLL)
+	thread->nevents = ISC_SOCKET_MAXEVENTS;
+	thread->epoll_events =
+		isc_mem_get(thread->manager->mctx,
+			    (thread->manager->maxsocks * sizeof(uint32_t)));
+
+	memset(thread->epoll_events, 0,
+	       thread->manager->maxsocks * sizeof(uint32_t));
+
+	thread->events =
+		isc_mem_get(thread->manager->mctx,
+			    sizeof(struct epoll_event) * thread->nevents);
+
+	thread->epoll_fd = epoll_create(thread->nevents);
+	if (thread->epoll_fd == -1) {
+		result = isc__errno2result(errno);
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "epoll_create failed: %s",
+				 strbuf);
+		return (result);
+	}
+
+	result = watch_fd(thread, thread->pipe_fds[0], SELECT_POKE_READ);
+	return (result);
+
+#elif defined(USE_DEVPOLL)
+	thread->nevents = ISC_SOCKET_MAXEVENTS;
+	result = isc_resource_getcurlimit(isc_resource_openfiles,
+					  &thread->open_max);
+	if (result != ISC_R_SUCCESS) {
+		thread->open_max = 64;
+	}
+	thread->calls = 0;
+	thread->events = isc_mem_get(thread->manager->mctx,
+				     sizeof(struct pollfd) * thread->nevents);
+
+	/*
+	 * Note: fdpollinfo should be able to support all possible FDs, so
+	 * it must have maxsocks entries (not nevents).
+	 */
+	thread->fdpollinfo =
+		isc_mem_get(thread->manager->mctx,
+			    sizeof(pollinfo_t) * thread->manager->maxsocks);
+	memset(thread->fdpollinfo, 0,
+	       sizeof(pollinfo_t) * thread->manager->maxsocks);
+	thread->devpoll_fd = open("/dev/poll", O_RDWR);
+	if (thread->devpoll_fd == -1) {
+		result = isc__errno2result(errno);
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "open(/dev/poll) failed: %s", strbuf);
+		isc_mem_put(thread->manager->mctx, thread->events,
+			    sizeof(struct pollfd) * thread->nevents);
+		isc_mem_put(thread->manager->mctx, thread->fdpollinfo,
+			    sizeof(pollinfo_t) * thread->manager->maxsocks);
+		return (result);
+	}
+	result = watch_fd(thread, thread->pipe_fds[0], SELECT_POKE_READ);
+	if (result != ISC_R_SUCCESS) {
+		close(thread->devpoll_fd);
+		isc_mem_put(thread->manager->mctx, thread->events,
+			    sizeof(struct pollfd) * thread->nevents);
+		isc_mem_put(thread->manager->mctx, thread->fdpollinfo,
+			    sizeof(pollinfo_t) * thread->manager->maxsocks);
+		return (result);
+	}
+
+	return (ISC_R_SUCCESS);
+#elif defined(USE_SELECT)
+	UNUSED(result);
+
+#if ISC_SOCKET_MAXSOCKETS > FD_SETSIZE
+	/*
+	 * Note: this code should also cover the case of MAXSOCKETS <=
+	 * FD_SETSIZE, but we separate the cases to avoid possible portability
+	 * issues regarding howmany() and the actual representation of fd_set.
+	 */
+	thread->fd_bufsize = howmany(manager->maxsocks, NFDBITS) *
+			     sizeof(fd_mask);
+#else  /* if ISC_SOCKET_MAXSOCKETS > FD_SETSIZE */
+	thread->fd_bufsize = sizeof(fd_set);
+#endif /* if ISC_SOCKET_MAXSOCKETS > FD_SETSIZE */
+
+	thread->read_fds = isc_mem_get(thread->manager->mctx,
+				       thread->fd_bufsize);
+	thread->read_fds_copy = isc_mem_get(thread->manager->mctx,
+					    thread->fd_bufsize);
+	thread->write_fds = isc_mem_get(thread->manager->mctx,
+					thread->fd_bufsize);
+	thread->write_fds_copy = isc_mem_get(thread->manager->mctx,
+					     thread->fd_bufsize);
+	memset(thread->read_fds, 0, thread->fd_bufsize);
+	memset(thread->write_fds, 0, thread->fd_bufsize);
+
+	(void)watch_fd(thread, thread->pipe_fds[0], SELECT_POKE_READ);
+	thread->maxfd = thread->pipe_fds[0];
+
+	return (ISC_R_SUCCESS);
+#endif /* USE_KQUEUE */
+}
+
+static void
+cleanup_thread(isc_mem_t *mctx, isc__socketthread_t *thread) {
+	isc_result_t result;
+	int i;
+
+	result = unwatch_fd(thread, thread->pipe_fds[0], SELECT_POKE_READ);
+	if (result != ISC_R_SUCCESS) {
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "epoll_ctl(DEL) failed");
+	}
+#ifdef USE_KQUEUE
+	close(thread->kqueue_fd);
+	isc_mem_put(mctx, thread->events,
+		    sizeof(struct kevent) * thread->nevents);
+#elif defined(USE_EPOLL)
+	close(thread->epoll_fd);
+
+	isc_mem_put(mctx, thread->events,
+		    sizeof(struct epoll_event) * thread->nevents);
+#elif defined(USE_DEVPOLL)
+	close(thread->devpoll_fd);
+	isc_mem_put(mctx, thread->events,
+		    sizeof(struct pollfd) * thread->nevents);
+	isc_mem_put(mctx, thread->fdpollinfo,
+		    sizeof(pollinfo_t) * thread->manager->maxsocks);
+#elif defined(USE_SELECT)
+	if (thread->read_fds != NULL) {
+		isc_mem_put(mctx, thread->read_fds, thread->fd_bufsize);
+	}
+	if (thread->read_fds_copy != NULL) {
+		isc_mem_put(mctx, thread->read_fds_copy, thread->fd_bufsize);
+	}
+	if (thread->write_fds != NULL) {
+		isc_mem_put(mctx, thread->write_fds, thread->fd_bufsize);
+	}
+	if (thread->write_fds_copy != NULL) {
+		isc_mem_put(mctx, thread->write_fds_copy, thread->fd_bufsize);
+	}
+#endif /* USE_KQUEUE */
+	for (i = 0; i < (int)thread->manager->maxsocks; i++) {
+		if (thread->fdstate[i] == CLOSE_PENDING) {
+			/* no need to lock */
+			(void)close(i);
+		}
+	}
+
+#if defined(USE_EPOLL)
+	isc_mem_put(thread->manager->mctx, thread->epoll_events,
+		    thread->manager->maxsocks * sizeof(uint32_t));
+#endif /* if defined(USE_EPOLL) */
+	isc_mem_put(thread->manager->mctx, thread->fds,
+		    thread->manager->maxsocks * sizeof(isc_socket_t *));
+	isc_mem_put(thread->manager->mctx, thread->fdstate,
+		    thread->manager->maxsocks * sizeof(int));
+
+	for (i = 0; i < FDLOCK_COUNT; i++) {
+		isc_mutex_destroy(&thread->fdlock[i]);
+	}
+	isc_mem_put(thread->manager->mctx, thread->fdlock,
+		    FDLOCK_COUNT * sizeof(isc_mutex_t));
+}
+
+isc_result_t
+isc_socketmgr_create(isc_mem_t *mctx, isc_socketmgr_t **managerp) {
+	return (isc_socketmgr_create2(mctx, managerp, 0, 1));
+}
+
+isc_result_t
+isc_socketmgr_create2(isc_mem_t *mctx, isc_socketmgr_t **managerp,
+		      unsigned int maxsocks, int nthreads) {
+	int i;
+	isc_socketmgr_t *manager;
+
+	REQUIRE(managerp != NULL && *managerp == NULL);
+
+	if (maxsocks == 0) {
+		maxsocks = ISC_SOCKET_MAXSOCKETS;
+	}
+
+	manager = isc_mem_get(mctx, sizeof(*manager));
+
+	/* zero-clear so that necessary cleanup on failure will be easy */
+	memset(manager, 0, sizeof(*manager));
+	manager->maxsocks = maxsocks;
+	manager->reserved = 0;
+	manager->maxudp = 0;
+	manager->nthreads = nthreads;
+	manager->stats = NULL;
+
+	manager->magic = SOCKET_MANAGER_MAGIC;
+	manager->mctx = NULL;
+	ISC_LIST_INIT(manager->socklist);
+	isc_mutex_init(&manager->lock);
+	isc_condition_init(&manager->shutdown_ok);
+
+	/*
+	 * Start up the select/poll thread.
+	 */
+	manager->threads = isc_mem_get(mctx, sizeof(isc__socketthread_t) *
+						     manager->nthreads);
+	isc_mem_attach(mctx, &manager->mctx);
+
+	for (i = 0; i < manager->nthreads; i++) {
+		manager->threads[i].manager = manager;
+		manager->threads[i].threadid = i;
+		setup_thread(&manager->threads[i]);
+		isc_thread_create(netthread, &manager->threads[i],
+				  &manager->threads[i].thread);
+		char tname[1024];
+		sprintf(tname, "isc-socket-%d", i);
+		isc_thread_setname(manager->threads[i].thread, tname);
+	}
+
+	*managerp = manager;
+
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_socketmgr_getmaxsockets(isc_socketmgr_t *manager, unsigned int *nsockp) {
+	REQUIRE(VALID_MANAGER(manager));
+	REQUIRE(nsockp != NULL);
+
+	*nsockp = manager->maxsocks;
+
+	return (ISC_R_SUCCESS);
+}
+
+void
+isc_socketmgr_setstats(isc_socketmgr_t *manager, isc_stats_t *stats) {
+	REQUIRE(VALID_MANAGER(manager));
+	REQUIRE(ISC_LIST_EMPTY(manager->socklist));
+	REQUIRE(manager->stats == NULL);
+	REQUIRE(isc_stats_ncounters(stats) == isc_sockstatscounter_max);
+
+	isc_stats_attach(stats, &manager->stats);
+}
+
+void
+isc_socketmgr_destroy(isc_socketmgr_t **managerp) {
+	isc_socketmgr_t *manager;
+
+	/*
+	 * Destroy a socket manager.
+	 */
+
+	REQUIRE(managerp != NULL);
+	manager = *managerp;
+	REQUIRE(VALID_MANAGER(manager));
+
+	LOCK(&manager->lock);
+
+	/*
+	 * Wait for all sockets to be destroyed.
+	 */
+	while (!ISC_LIST_EMPTY(manager->socklist)) {
+		manager_log(manager, CREATION, "sockets exist");
+		WAIT(&manager->shutdown_ok, &manager->lock);
+	}
+
+	UNLOCK(&manager->lock);
+
+	/*
+	 * Here, poke our select/poll thread.  Do this by closing the write
+	 * half of the pipe, which will send EOF to the read half.
+	 * This is currently a no-op in the non-threaded case.
+	 */
+	for (int i = 0; i < manager->nthreads; i++) {
+		select_poke(manager, i, 0, SELECT_POKE_SHUTDOWN);
+	}
+
+	/*
+	 * Wait for thread to exit.
+	 */
+	for (int i = 0; i < manager->nthreads; i++) {
+		isc_thread_join(manager->threads[i].thread, NULL);
+		cleanup_thread(manager->mctx, &manager->threads[i]);
+	}
+	/*
+	 * Clean up.
+	 */
+	isc_mem_put(manager->mctx, manager->threads,
+		    sizeof(isc__socketthread_t) * manager->nthreads);
+	(void)isc_condition_destroy(&manager->shutdown_ok);
+
+	if (manager->stats != NULL) {
+		isc_stats_detach(&manager->stats);
+	}
+	isc_mutex_destroy(&manager->lock);
+	manager->magic = 0;
+	isc_mem_putanddetach(&manager->mctx, manager, sizeof(*manager));
+
+	*managerp = NULL;
+}
+
+static isc_result_t
+socket_recv(isc_socket_t *sock, isc_socketevent_t *dev, isc_task_t *task,
+	    unsigned int flags) {
+	int io_state;
+	bool have_lock = false;
+	isc_task_t *ntask = NULL;
+	isc_result_t result = ISC_R_SUCCESS;
+
+	dev->ev_sender = task;
+
+	if (sock->type == isc_sockettype_udp) {
+		io_state = doio_recv(sock, dev);
+	} else {
+		LOCK(&sock->lock);
+		have_lock = true;
+
+		if (ISC_LIST_EMPTY(sock->recv_list)) {
+			io_state = doio_recv(sock, dev);
+		} else {
+			io_state = DOIO_SOFT;
+		}
+	}
+
+	switch (io_state) {
+	case DOIO_SOFT:
+		/*
+		 * We couldn't read all or part of the request right now, so
+		 * queue it.
+		 *
+		 * Attach to socket and to task
+		 */
+		isc_task_attach(task, &ntask);
+		dev->attributes |= ISC_SOCKEVENTATTR_ATTACHED;
+
+		if (!have_lock) {
+			LOCK(&sock->lock);
+			have_lock = true;
+		}
+
+		/*
+		 * Enqueue the request.  If the socket was previously not being
+		 * watched, poke the watcher to start paying attention to it.
+		 */
+		bool do_poke = ISC_LIST_EMPTY(sock->recv_list);
+		ISC_LIST_ENQUEUE(sock->recv_list, dev, ev_link);
+		if (do_poke) {
+			select_poke(sock->manager, sock->threadid, sock->fd,
+				    SELECT_POKE_READ);
+		}
+
+		socket_log(sock, NULL, EVENT,
+			   "socket_recv: event %p -> task %p", dev, ntask);
+
+		if ((flags & ISC_SOCKFLAG_IMMEDIATE) != 0) {
+			result = ISC_R_INPROGRESS;
+		}
+		break;
+
+	case DOIO_EOF:
+		dev->result = ISC_R_EOF;
+		FALLTHROUGH;
+
+	case DOIO_HARD:
+	case DOIO_SUCCESS:
+		if ((flags & ISC_SOCKFLAG_IMMEDIATE) == 0) {
+			send_recvdone_event(sock, &dev);
+		}
+		break;
+	}
+
+	if (have_lock) {
+		UNLOCK(&sock->lock);
+	}
+
+	return (result);
+}
+
+isc_result_t
+isc_socket_recv(isc_socket_t *sock, isc_region_t *region, unsigned int minimum,
+		isc_task_t *task, isc_taskaction_t action, void *arg) {
+	isc_socketevent_t *dev;
+	isc_socketmgr_t *manager;
+
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(action != NULL);
+
+	manager = sock->manager;
+	REQUIRE(VALID_MANAGER(manager));
+
+	INSIST(sock->bound);
+
+	dev = allocate_socketevent(manager->mctx, sock, ISC_SOCKEVENT_RECVDONE,
+				   action, arg);
+	if (dev == NULL) {
+		return (ISC_R_NOMEMORY);
+	}
+
+	return (isc_socket_recv2(sock, region, minimum, task, dev, 0));
+}
+
+isc_result_t
+isc_socket_recv2(isc_socket_t *sock, isc_region_t *region, unsigned int minimum,
+		 isc_task_t *task, isc_socketevent_t *event,
+		 unsigned int flags) {
+	event->ev_sender = sock;
+	event->result = ISC_R_UNSET;
+	event->region = *region;
+	event->n = 0;
+	event->offset = 0;
+	event->attributes = 0;
+
+	/*
+	 * UDP sockets are always partial read.
+	 */
+	if (sock->type == isc_sockettype_udp) {
+		event->minimum = 1;
+	} else {
+		if (minimum == 0) {
+			event->minimum = region->length;
+		} else {
+			event->minimum = minimum;
+		}
+	}
+
+	return (socket_recv(sock, event, task, flags));
+}
+
+static isc_result_t
+socket_send(isc_socket_t *sock, isc_socketevent_t *dev, isc_task_t *task,
+	    const isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
+	    unsigned int flags) {
+	int io_state;
+	bool have_lock = false;
+	isc_task_t *ntask = NULL;
+	isc_result_t result = ISC_R_SUCCESS;
+
+	dev->ev_sender = task;
+
+	set_dev_address(address, sock, dev);
+	if (pktinfo != NULL) {
+		dev->attributes |= ISC_SOCKEVENTATTR_PKTINFO;
+		dev->pktinfo = *pktinfo;
+
+		if (!isc_sockaddr_issitelocal(&dev->address) &&
+		    !isc_sockaddr_islinklocal(&dev->address))
+		{
+			socket_log(sock, NULL, TRACE,
+				   "pktinfo structure provided, ifindex %u "
+				   "(set to 0)",
+				   pktinfo->ipi6_ifindex);
+
+			/*
+			 * Set the pktinfo index to 0 here, to let the
+			 * kernel decide what interface it should send on.
+			 */
+			dev->pktinfo.ipi6_ifindex = 0;
+		}
+	}
+
+	if (sock->type == isc_sockettype_udp) {
+		io_state = doio_send(sock, dev);
+	} else {
+		LOCK(&sock->lock);
+		have_lock = true;
+
+		if (ISC_LIST_EMPTY(sock->send_list)) {
+			io_state = doio_send(sock, dev);
+		} else {
+			io_state = DOIO_SOFT;
+		}
+	}
+
+	switch (io_state) {
+	case DOIO_SOFT:
+		/*
+		 * We couldn't send all or part of the request right now, so
+		 * queue it unless ISC_SOCKFLAG_NORETRY is set.
+		 */
+		if ((flags & ISC_SOCKFLAG_NORETRY) == 0) {
+			isc_task_attach(task, &ntask);
+			dev->attributes |= ISC_SOCKEVENTATTR_ATTACHED;
+
+			if (!have_lock) {
+				LOCK(&sock->lock);
+				have_lock = true;
+			}
+
+			/*
+			 * Enqueue the request.  If the socket was previously
+			 * not being watched, poke the watcher to start
+			 * paying attention to it.
+			 */
+			bool do_poke = ISC_LIST_EMPTY(sock->send_list);
+			ISC_LIST_ENQUEUE(sock->send_list, dev, ev_link);
+			if (do_poke) {
+				select_poke(sock->manager, sock->threadid,
+					    sock->fd, SELECT_POKE_WRITE);
+			}
+			socket_log(sock, NULL, EVENT,
+				   "socket_send: event %p -> task %p", dev,
+				   ntask);
+
+			if ((flags & ISC_SOCKFLAG_IMMEDIATE) != 0) {
+				result = ISC_R_INPROGRESS;
+			}
+			break;
+		}
+
+		FALLTHROUGH;
+
+	case DOIO_HARD:
+	case DOIO_SUCCESS:
+		if (!have_lock) {
+			LOCK(&sock->lock);
+			have_lock = true;
+		}
+		if ((flags & ISC_SOCKFLAG_IMMEDIATE) == 0) {
+			send_senddone_event(sock, &dev);
+		}
+		break;
+	}
+
+	if (have_lock) {
+		UNLOCK(&sock->lock);
+	}
+
+	return (result);
+}
+
+isc_result_t
+isc_socket_send(isc_socket_t *sock, isc_region_t *region, isc_task_t *task,
+		isc_taskaction_t action, void *arg) {
+	/*
+	 * REQUIRE() checking is performed in isc_socket_sendto().
+	 */
+	return (isc_socket_sendto(sock, region, task, action, arg, NULL, NULL));
+}
+
+isc_result_t
+isc_socket_sendto(isc_socket_t *sock, isc_region_t *region, isc_task_t *task,
+		  isc_taskaction_t action, void *arg,
+		  const isc_sockaddr_t *address, struct in6_pktinfo *pktinfo) {
+	isc_socketevent_t *dev;
+	isc_socketmgr_t *manager;
+
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(region != NULL);
+	REQUIRE(task != NULL);
+	REQUIRE(action != NULL);
+
+	manager = sock->manager;
+	REQUIRE(VALID_MANAGER(manager));
+
+	INSIST(sock->bound);
+
+	dev = allocate_socketevent(manager->mctx, sock, ISC_SOCKEVENT_SENDDONE,
+				   action, arg);
+	if (dev == NULL) {
+		return (ISC_R_NOMEMORY);
+	}
+
+	dev->region = *region;
+
+	return (socket_send(sock, dev, task, address, pktinfo, 0));
+}
+
+isc_result_t
+isc_socket_sendto2(isc_socket_t *sock, isc_region_t *region, isc_task_t *task,
+		   const isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
+		   isc_socketevent_t *event, unsigned int flags) {
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE((flags & ~(ISC_SOCKFLAG_IMMEDIATE | ISC_SOCKFLAG_NORETRY)) ==
+		0);
+	if ((flags & ISC_SOCKFLAG_NORETRY) != 0) {
+		REQUIRE(sock->type == isc_sockettype_udp);
+	}
+	event->ev_sender = sock;
+	event->result = ISC_R_UNSET;
+	event->region = *region;
+	event->n = 0;
+	event->offset = 0;
+	event->attributes &= ~ISC_SOCKEVENTATTR_ATTACHED;
+
+	return (socket_send(sock, event, task, address, pktinfo, flags));
+}
+
+void
+isc_socket_cleanunix(const isc_sockaddr_t *sockaddr, bool active) {
+#ifdef ISC_PLATFORM_HAVESYSUNH
+	int s;
+	struct stat sb;
+	char strbuf[ISC_STRERRORSIZE];
+
+	if (sockaddr->type.sa.sa_family != AF_UNIX) {
+		return;
+	}
+
+#ifndef S_ISSOCK
+#if defined(S_IFMT) && defined(S_IFSOCK)
+#define S_ISSOCK(mode) ((mode & S_IFMT) == S_IFSOCK)
+#elif defined(_S_IFMT) && defined(S_IFSOCK)
+#define S_ISSOCK(mode) ((mode & _S_IFMT) == S_IFSOCK)
+#endif /* if defined(S_IFMT) && defined(S_IFSOCK) */
+#endif /* ifndef S_ISSOCK */
+
+#ifndef S_ISFIFO
+#if defined(S_IFMT) && defined(S_IFIFO)
+#define S_ISFIFO(mode) ((mode & S_IFMT) == S_IFIFO)
+#elif defined(_S_IFMT) && defined(S_IFIFO)
+#define S_ISFIFO(mode) ((mode & _S_IFMT) == S_IFIFO)
+#endif /* if defined(S_IFMT) && defined(S_IFIFO) */
+#endif /* ifndef S_ISFIFO */
+
+#if !defined(S_ISFIFO) && !defined(S_ISSOCK)
+/* cppcheck-suppress preprocessorErrorDirective */
+#error \
+	You need to define S_ISFIFO and S_ISSOCK as appropriate for your platform.  See <sys/stat.h>.
+#endif /* if !defined(S_ISFIFO) && !defined(S_ISSOCK) */
+
+#ifndef S_ISFIFO
+#define S_ISFIFO(mode) 0
+#endif /* ifndef S_ISFIFO */
+
+#ifndef S_ISSOCK
+#define S_ISSOCK(mode) 0
+#endif /* ifndef S_ISSOCK */
+
+	if (stat(sockaddr->type.sunix.sun_path, &sb) < 0) {
+		switch (errno) {
+		case ENOENT:
+			if (active) { /* We exited cleanly last time */
+				break;
+			}
+			FALLTHROUGH;
+		default:
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET,
+				      active ? ISC_LOG_ERROR : ISC_LOG_WARNING,
+				      "isc_socket_cleanunix: stat(%s): %s",
+				      sockaddr->type.sunix.sun_path, strbuf);
+			return;
+		}
+	} else {
+		if (!(S_ISSOCK(sb.st_mode) || S_ISFIFO(sb.st_mode))) {
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET,
+				      active ? ISC_LOG_ERROR : ISC_LOG_WARNING,
+				      "isc_socket_cleanunix: %s: not a socket",
+				      sockaddr->type.sunix.sun_path);
+			return;
+		}
+	}
+
+	if (active) {
+		if (unlink(sockaddr->type.sunix.sun_path) < 0) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+				      "isc_socket_cleanunix: unlink(%s): %s",
+				      sockaddr->type.sunix.sun_path, strbuf);
+		}
+		return;
+	}
+
+	s = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (s < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
+			      "isc_socket_cleanunix: socket(%s): %s",
+			      sockaddr->type.sunix.sun_path, strbuf);
+		return;
+	}
+
+	if (connect(s, (const struct sockaddr *)&sockaddr->type.sunix,
+		    sizeof(sockaddr->type.sunix)) < 0)
+	{
+		switch (errno) {
+		case ECONNREFUSED:
+		case ECONNRESET:
+			if (unlink(sockaddr->type.sunix.sun_path) < 0) {
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				isc_log_write(
+					isc_lctx, ISC_LOGCATEGORY_GENERAL,
+					ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
+					"isc_socket_cleanunix: "
+					"unlink(%s): %s",
+					sockaddr->type.sunix.sun_path, strbuf);
+			}
+			break;
+		default:
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
+				      "isc_socket_cleanunix: connect(%s): %s",
+				      sockaddr->type.sunix.sun_path, strbuf);
+			break;
+		}
+	}
+	close(s);
+#else  /* ifdef ISC_PLATFORM_HAVESYSUNH */
+	UNUSED(sockaddr);
+	UNUSED(active);
+#endif /* ifdef ISC_PLATFORM_HAVESYSUNH */
+}
+
+isc_result_t
+isc_socket_permunix(const isc_sockaddr_t *sockaddr, uint32_t perm,
+		    uint32_t owner, uint32_t group) {
+#ifdef ISC_PLATFORM_HAVESYSUNH
+	isc_result_t result = ISC_R_SUCCESS;
+	char strbuf[ISC_STRERRORSIZE];
+	char path[sizeof(sockaddr->type.sunix.sun_path)];
+#ifdef NEED_SECURE_DIRECTORY
+	char *slash;
+#endif /* ifdef NEED_SECURE_DIRECTORY */
+
+	REQUIRE(sockaddr->type.sa.sa_family == AF_UNIX);
+	INSIST(strlen(sockaddr->type.sunix.sun_path) < sizeof(path));
+	strlcpy(path, sockaddr->type.sunix.sun_path, sizeof(path));
+
+#ifdef NEED_SECURE_DIRECTORY
+	slash = strrchr(path, '/');
+	if (slash != NULL) {
+		if (slash != path) {
+			*slash = '\0';
+		} else {
+			strlcpy(path, "/", sizeof(path));
+		}
+	} else {
+		strlcpy(path, ".", sizeof(path));
+	}
+#endif /* ifdef NEED_SECURE_DIRECTORY */
+
+	if (chmod(path, perm) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+			      "isc_socket_permunix: chmod(%s, %d): %s", path,
+			      perm, strbuf);
+		result = ISC_R_FAILURE;
+	}
+	if (chown(path, owner, group) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+			      "isc_socket_permunix: chown(%s, %d, %d): %s",
+			      path, owner, group, strbuf);
+		result = ISC_R_FAILURE;
+	}
+	return (result);
+#else  /* ifdef ISC_PLATFORM_HAVESYSUNH */
+	UNUSED(sockaddr);
+	UNUSED(perm);
+	UNUSED(owner);
+	UNUSED(group);
+	return (ISC_R_NOTIMPLEMENTED);
+#endif /* ifdef ISC_PLATFORM_HAVESYSUNH */
+}
+
+isc_result_t
+isc_socket_bind(isc_socket_t *sock, const isc_sockaddr_t *sockaddr,
+		isc_socket_options_t options) {
+	char strbuf[ISC_STRERRORSIZE];
+	int on = 1;
+
+	REQUIRE(VALID_SOCKET(sock));
+
+	LOCK(&sock->lock);
+
+	INSIST(!sock->bound);
+	INSIST(!sock->dupped);
+
+	if (sock->pf != sockaddr->type.sa.sa_family) {
+		UNLOCK(&sock->lock);
+		return (ISC_R_FAMILYMISMATCH);
+	}
+
+	/*
+	 * Only set SO_REUSEADDR when we want a specific port.
+	 */
+#ifdef AF_UNIX
+	if (sock->pf == AF_UNIX) {
+		goto bind_socket;
+	}
+#endif /* ifdef AF_UNIX */
+	if ((options & ISC_SOCKET_REUSEADDRESS) != 0 &&
+	    isc_sockaddr_getport(sockaddr) != (in_port_t)0)
+	{
+		if (setsockopt(sock->fd, SOL_SOCKET, SO_REUSEADDR, (void *)&on,
+			       sizeof(on)) < 0)
+		{
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d) failed", sock->fd);
+		}
+#if defined(__FreeBSD_kernel__) && defined(SO_REUSEPORT_LB)
+		if (setsockopt(sock->fd, SOL_SOCKET, SO_REUSEPORT_LB,
+			       (void *)&on, sizeof(on)) < 0)
+		{
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d) failed", sock->fd);
+		}
+#elif defined(__linux__) && defined(SO_REUSEPORT)
+		if (setsockopt(sock->fd, SOL_SOCKET, SO_REUSEPORT, (void *)&on,
+			       sizeof(on)) < 0)
+		{
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d) failed", sock->fd);
+		}
+#endif		/* if defined(__FreeBSD_kernel__) && defined(SO_REUSEPORT_LB) */
+		/* Press on... */
+	}
+#ifdef AF_UNIX
+bind_socket:
+#endif /* ifdef AF_UNIX */
+	if (bind(sock->fd, &sockaddr->type.sa, sockaddr->length) < 0) {
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_BINDFAIL]);
+
+		UNLOCK(&sock->lock);
+		switch (errno) {
+		case EACCES:
+			return (ISC_R_NOPERM);
+		case EADDRNOTAVAIL:
+			return (ISC_R_ADDRNOTAVAIL);
+		case EADDRINUSE:
+			return (ISC_R_ADDRINUSE);
+		case EINVAL:
+			return (ISC_R_BOUND);
+		default:
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__, "bind: %s",
+					 strbuf);
+			return (ISC_R_UNEXPECTED);
+		}
+	}
+
+	socket_log(sock, sockaddr, TRACE, "bound");
+	sock->bound = 1;
+
+	UNLOCK(&sock->lock);
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * Enable this only for specific OS versions, and only when they have repaired
+ * their problems with it.  Until then, this is is broken and needs to be
+ * disabled by default.  See RT22589 for details.
+ */
+#undef ENABLE_ACCEPTFILTER
+
+isc_result_t
+isc_socket_filter(isc_socket_t *sock, const char *filter) {
+#if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER)
+	char strbuf[ISC_STRERRORSIZE];
+	struct accept_filter_arg afa;
+#else  /* if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER) */
+	UNUSED(sock);
+	UNUSED(filter);
+#endif /* if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER) */
+
+	REQUIRE(VALID_SOCKET(sock));
+
+#if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER)
+	bzero(&afa, sizeof(afa));
+	strlcpy(afa.af_name, filter, sizeof(afa.af_name));
+	if (setsockopt(sock->fd, SOL_SOCKET, SO_ACCEPTFILTER, &afa,
+		       sizeof(afa)) == -1)
+	{
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		socket_log(sock, NULL, CREATION,
+			   "setsockopt(SO_ACCEPTFILTER): %s", strbuf);
+		return (ISC_R_FAILURE);
+	}
+	return (ISC_R_SUCCESS);
+#else  /* if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER) */
+	return (ISC_R_NOTIMPLEMENTED);
+#endif /* if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER) */
+}
+
+/*
+ * Try enabling TCP Fast Open for a given socket if the OS supports it.
+ */
+static void
+set_tcp_fastopen(isc_socket_t *sock, unsigned int backlog) {
+#if defined(ENABLE_TCP_FASTOPEN) && defined(TCP_FASTOPEN)
+	char strbuf[ISC_STRERRORSIZE];
+
+/*
+ * FreeBSD, as of versions 10.3 and 11.0, defines TCP_FASTOPEN while also
+ * shipping a default kernel without TFO support, so we special-case it by
+ * performing an additional runtime check for TFO support using sysctl to
+ * prevent setsockopt() errors from being logged.
+ */
+#if defined(__FreeBSD__) && defined(HAVE_SYSCTLBYNAME)
+#define SYSCTL_TFO "net.inet.tcp.fastopen.enabled"
+	unsigned int enabled;
+	size_t enabledlen = sizeof(enabled);
+	static bool tfo_notice_logged = false;
+
+	if (sysctlbyname(SYSCTL_TFO, &enabled, &enabledlen, NULL, 0) < 0) {
+		/*
+		 * This kernel does not support TCP Fast Open.  There is
+		 * nothing more we can do.
+		 */
+		return;
+	} else if (enabled == 0) {
+		/*
+		 * This kernel does support TCP Fast Open, but it is disabled
+		 * by sysctl.  Notify the user, but do not nag.
+		 */
+		if (!tfo_notice_logged) {
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_NOTICE,
+				      "TCP_FASTOPEN support is disabled by "
+				      "sysctl (" SYSCTL_TFO " = 0)");
+			tfo_notice_logged = true;
+		}
+		return;
+	}
+#endif /* if defined(__FreeBSD__) && defined(HAVE_SYSCTLBYNAME) */
+
+#ifdef __APPLE__
+	backlog = 1;
+#else  /* ifdef __APPLE__ */
+	backlog = backlog / 2;
+	if (backlog == 0) {
+		backlog = 1;
+	}
+#endif /* ifdef __APPLE__ */
+	if (setsockopt(sock->fd, IPPROTO_TCP, TCP_FASTOPEN, (void *)&backlog,
+		       sizeof(backlog)) < 0)
+	{
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "setsockopt(%d, TCP_FASTOPEN) failed with %s",
+				 sock->fd, strbuf);
+		/* TCP_FASTOPEN is experimental so ignore failures */
+	}
+#else  /* if defined(ENABLE_TCP_FASTOPEN) && defined(TCP_FASTOPEN) */
+	UNUSED(sock);
+	UNUSED(backlog);
+#endif /* if defined(ENABLE_TCP_FASTOPEN) && defined(TCP_FASTOPEN) */
+}
+
+/*
+ * Set up to listen on a given socket.  We do this by creating an internal
+ * event that will be dispatched when the socket has read activity.  The
+ * watcher will send the internal event to the task when there is a new
+ * connection.
+ *
+ * Unlike in read, we don't preallocate a done event here.  Every time there
+ * is a new connection we'll have to allocate a new one anyway, so we might
+ * as well keep things simple rather than having to track them.
+ */
+isc_result_t
+isc_socket_listen(isc_socket_t *sock, unsigned int backlog) {
+	char strbuf[ISC_STRERRORSIZE];
+
+	REQUIRE(VALID_SOCKET(sock));
+
+	LOCK(&sock->lock);
+
+	REQUIRE(!sock->listener);
+	REQUIRE(sock->bound);
+	REQUIRE(sock->type == isc_sockettype_tcp ||
+		sock->type == isc_sockettype_unix);
+
+	if (backlog == 0) {
+		backlog = SOMAXCONN;
+	}
+
+	if (listen(sock->fd, (int)backlog) < 0) {
+		UNLOCK(&sock->lock);
+		strerror_r(errno, strbuf, sizeof(strbuf));
+
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "listen: %s", strbuf);
+
+		return (ISC_R_UNEXPECTED);
+	}
+
+	set_tcp_fastopen(sock, backlog);
+
+	sock->listener = 1;
+
+	UNLOCK(&sock->lock);
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * This should try to do aggressive accept() XXXMLG
+ */
+isc_result_t
+isc_socket_accept(isc_socket_t *sock, isc_task_t *task, isc_taskaction_t action,
+		  void *arg) {
+	isc_socket_newconnev_t *dev;
+	isc_socketmgr_t *manager;
+	isc_task_t *ntask = NULL;
+	isc_socket_t *nsock;
+	isc_result_t result;
+	bool do_poke = false;
+
+	REQUIRE(VALID_SOCKET(sock));
+	manager = sock->manager;
+	REQUIRE(VALID_MANAGER(manager));
+
+	LOCK(&sock->lock);
+
+	REQUIRE(sock->listener);
+
+	/*
+	 * Sender field is overloaded here with the task we will be sending
+	 * this event to.  Just before the actual event is delivered the
+	 * actual ev_sender will be touched up to be the socket.
+	 */
+	dev = (isc_socket_newconnev_t *)isc_event_allocate(
+		manager->mctx, task, ISC_SOCKEVENT_NEWCONN, action, arg,
+		sizeof(*dev));
+	ISC_LINK_INIT(dev, ev_link);
+
+	result = allocate_socket(manager, sock->type, &nsock);
+	if (result != ISC_R_SUCCESS) {
+		isc_event_free(ISC_EVENT_PTR(&dev));
+		UNLOCK(&sock->lock);
+		return (result);
+	}
+
+	/*
+	 * Attach to socket and to task.
+	 */
+	isc_task_attach(task, &ntask);
+	if (isc_task_exiting(ntask)) {
+		free_socket(&nsock);
+		isc_task_detach(&ntask);
+		isc_event_free(ISC_EVENT_PTR(&dev));
+		UNLOCK(&sock->lock);
+		return (ISC_R_SHUTTINGDOWN);
+	}
+	isc_refcount_increment0(&nsock->references);
+	nsock->statsindex = sock->statsindex;
+
+	dev->ev_sender = ntask;
+	dev->newsocket = nsock;
+
+	/*
+	 * Poke watcher here.  We still have the socket locked, so there
+	 * is no race condition.  We will keep the lock for such a short
+	 * bit of time waking it up now or later won't matter all that much.
+	 */
+	do_poke = ISC_LIST_EMPTY(sock->accept_list);
+	ISC_LIST_ENQUEUE(sock->accept_list, dev, ev_link);
+	if (do_poke) {
+		select_poke(manager, sock->threadid, sock->fd,
+			    SELECT_POKE_ACCEPT);
+	}
+	UNLOCK(&sock->lock);
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_socket_connect(isc_socket_t *sock, const isc_sockaddr_t *addr,
+		   isc_task_t *task, isc_taskaction_t action, void *arg) {
+	isc_socket_connev_t *dev;
+	isc_task_t *ntask = NULL;
+	isc_socketmgr_t *manager;
+	int cc;
+	char strbuf[ISC_STRERRORSIZE];
+	char addrbuf[ISC_SOCKADDR_FORMATSIZE];
+
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(addr != NULL);
+	REQUIRE(task != NULL);
+	REQUIRE(action != NULL);
+
+	manager = sock->manager;
+	REQUIRE(VALID_MANAGER(manager));
+	REQUIRE(addr != NULL);
+
+	if (isc_sockaddr_ismulticast(addr)) {
+		return (ISC_R_MULTICAST);
+	}
+
+	LOCK(&sock->lock);
+
+	dev = (isc_socket_connev_t *)isc_event_allocate(
+		manager->mctx, sock, ISC_SOCKEVENT_CONNECT, action, arg,
+		sizeof(*dev));
+	ISC_LINK_INIT(dev, ev_link);
+
+	if (sock->connecting) {
+		INSIST(isc_sockaddr_equal(&sock->peer_address, addr));
+		goto queue;
+	}
+
+	if (sock->connected) {
+		INSIST(isc_sockaddr_equal(&sock->peer_address, addr));
+		dev->result = ISC_R_SUCCESS;
+		isc_task_sendto(task, ISC_EVENT_PTR(&dev), sock->threadid);
+
+		UNLOCK(&sock->lock);
+
+		return (ISC_R_SUCCESS);
+	}
+
+	/*
+	 * Try to do the connect right away, as there can be only one
+	 * outstanding, and it might happen to complete.
+	 */
+	sock->peer_address = *addr;
+	cc = connect(sock->fd, &addr->type.sa, addr->length);
+	if (cc < 0) {
+		/*
+		 * The socket is nonblocking and the connection cannot be
+		 * completed immediately.  It is possible to select(2) or
+		 * poll(2) for completion by selecting the socket for writing.
+		 * After select(2) indicates writability, use getsockopt(2) to
+		 * read the SO_ERROR option at level SOL_SOCKET to determine
+		 * whether connect() completed successfully (SO_ERROR is zero)
+		 * or unsuccessfully (SO_ERROR is one of the usual error codes
+		 * listed here, explaining the reason for the failure).
+		 */
+		if (sock->type == isc_sockettype_udp && errno == EINPROGRESS) {
+			cc = 0;
+			goto success;
+		}
+		if (SOFT_ERROR(errno) || errno == EINPROGRESS) {
+			goto queue;
+		}
+
+		switch (errno) {
+#define ERROR_MATCH(a, b)        \
+	case a:                  \
+		dev->result = b; \
+		goto err_exit;
+			ERROR_MATCH(EACCES, ISC_R_NOPERM);
+			ERROR_MATCH(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
+			ERROR_MATCH(EAFNOSUPPORT, ISC_R_ADDRNOTAVAIL);
+			ERROR_MATCH(ECONNREFUSED, ISC_R_CONNREFUSED);
+			ERROR_MATCH(EHOSTUNREACH, ISC_R_HOSTUNREACH);
+#ifdef EHOSTDOWN
+			ERROR_MATCH(EHOSTDOWN, ISC_R_HOSTUNREACH);
+#endif /* ifdef EHOSTDOWN */
+			ERROR_MATCH(ENETUNREACH, ISC_R_NETUNREACH);
+			ERROR_MATCH(ENOBUFS, ISC_R_NORESOURCES);
+			ERROR_MATCH(EPERM, ISC_R_HOSTUNREACH);
+			ERROR_MATCH(EPIPE, ISC_R_NOTCONNECTED);
+			ERROR_MATCH(ETIMEDOUT, ISC_R_TIMEDOUT);
+			ERROR_MATCH(ECONNRESET, ISC_R_CONNECTIONRESET);
+#undef ERROR_MATCH
+		}
+
+		sock->connected = 0;
+
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_sockaddr_format(addr, addrbuf, sizeof(addrbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "connect(%s) %d/%s",
+				 addrbuf, errno, strbuf);
+
+		UNLOCK(&sock->lock);
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_CONNECTFAIL]);
+		isc_event_free(ISC_EVENT_PTR(&dev));
+		return (ISC_R_UNEXPECTED);
+
+	err_exit:
+		sock->connected = 0;
+		isc_task_sendto(task, ISC_EVENT_PTR(&dev), sock->threadid);
+
+		UNLOCK(&sock->lock);
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_CONNECTFAIL]);
+		return (ISC_R_SUCCESS);
+	}
+
+	/*
+	 * If connect completed, fire off the done event.
+	 */
+success:
+	if (cc == 0) {
+		sock->connected = 1;
+		sock->bound = 1;
+		dev->result = ISC_R_SUCCESS;
+		isc_task_sendto(task, ISC_EVENT_PTR(&dev), sock->threadid);
+
+		UNLOCK(&sock->lock);
+
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_CONNECT]);
+
+		return (ISC_R_SUCCESS);
+	}
+
+queue:
+
+	/*
+	 * Attach to task.
+	 */
+	isc_task_attach(task, &ntask);
+
+	dev->ev_sender = ntask;
+
+	/*
+	 * Poke watcher here.  We still have the socket locked, so there
+	 * is no race condition.  We will keep the lock for such a short
+	 * bit of time waking it up now or later won't matter all that much.
+	 */
+	bool do_poke = ISC_LIST_EMPTY(sock->connect_list);
+	ISC_LIST_ENQUEUE(sock->connect_list, dev, ev_link);
+	if (do_poke && !sock->connecting) {
+		sock->connecting = 1;
+		select_poke(manager, sock->threadid, sock->fd,
+			    SELECT_POKE_CONNECT);
+	}
+
+	UNLOCK(&sock->lock);
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * Called when a socket with a pending connect() finishes.
+ */
+static void
+internal_connect(isc_socket_t *sock) {
+	isc_socket_connev_t *dev;
+	int cc;
+	isc_result_t result;
+	socklen_t optlen;
+	char strbuf[ISC_STRERRORSIZE];
+	char peerbuf[ISC_SOCKADDR_FORMATSIZE];
+
+	INSIST(VALID_SOCKET(sock));
+	REQUIRE(sock->fd >= 0);
+
+	/*
+	 * Get the first item off the connect list.
+	 * If it is empty, unlock the socket and return.
+	 */
+	dev = ISC_LIST_HEAD(sock->connect_list);
+	if (dev == NULL) {
+		INSIST(!sock->connecting);
+		goto finish;
+	}
+
+	INSIST(sock->connecting);
+	sock->connecting = 0;
+
+	/*
+	 * Get any possible error status here.
+	 */
+	optlen = sizeof(cc);
+	if (getsockopt(sock->fd, SOL_SOCKET, SO_ERROR, (void *)&cc,
+		       (void *)&optlen) != 0)
+	{
+		cc = errno;
+	} else {
+		errno = cc;
+	}
+
+	if (errno != 0) {
+		/*
+		 * If the error is EAGAIN, just re-select on this
+		 * fd and pretend nothing strange happened.
+		 */
+		if (SOFT_ERROR(errno) || errno == EINPROGRESS) {
+			sock->connecting = 1;
+			return;
+		}
+
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_CONNECTFAIL]);
+
+		/*
+		 * Translate other errors into ISC_R_* flavors.
+		 */
+		switch (errno) {
+#define ERROR_MATCH(a, b)   \
+	case a:             \
+		result = b; \
+		break;
+			ERROR_MATCH(EACCES, ISC_R_NOPERM);
+			ERROR_MATCH(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
+			ERROR_MATCH(EAFNOSUPPORT, ISC_R_ADDRNOTAVAIL);
+			ERROR_MATCH(ECONNREFUSED, ISC_R_CONNREFUSED);
+			ERROR_MATCH(EHOSTUNREACH, ISC_R_HOSTUNREACH);
+#ifdef EHOSTDOWN
+			ERROR_MATCH(EHOSTDOWN, ISC_R_HOSTUNREACH);
+#endif /* ifdef EHOSTDOWN */
+			ERROR_MATCH(ENETUNREACH, ISC_R_NETUNREACH);
+			ERROR_MATCH(ENOBUFS, ISC_R_NORESOURCES);
+			ERROR_MATCH(EPERM, ISC_R_HOSTUNREACH);
+			ERROR_MATCH(EPIPE, ISC_R_NOTCONNECTED);
+			ERROR_MATCH(ETIMEDOUT, ISC_R_TIMEDOUT);
+			ERROR_MATCH(ECONNRESET, ISC_R_CONNECTIONRESET);
+#undef ERROR_MATCH
+		default:
+			result = ISC_R_UNEXPECTED;
+			isc_sockaddr_format(&sock->peer_address, peerbuf,
+					    sizeof(peerbuf));
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "internal_connect: connect(%s) %s",
+					 peerbuf, strbuf);
+		}
+	} else {
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_CONNECT]);
+		result = ISC_R_SUCCESS;
+		sock->connected = 1;
+		sock->bound = 1;
+	}
+
+	do {
+		dev->result = result;
+		send_connectdone_event(sock, &dev);
+		dev = ISC_LIST_HEAD(sock->connect_list);
+	} while (dev != NULL);
+
+finish:
+	unwatch_fd(&sock->manager->threads[sock->threadid], sock->fd,
+		   SELECT_POKE_CONNECT);
+}
+
+isc_result_t
+isc_socket_getpeername(isc_socket_t *sock, isc_sockaddr_t *addressp) {
+	isc_result_t result;
+
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(addressp != NULL);
+
+	LOCK(&sock->lock);
+
+	if (sock->connected) {
+		*addressp = sock->peer_address;
+		result = ISC_R_SUCCESS;
+	} else {
+		result = ISC_R_NOTCONNECTED;
+	}
+
+	UNLOCK(&sock->lock);
+
+	return (result);
+}
+
+isc_result_t
+isc_socket_getsockname(isc_socket_t *sock, isc_sockaddr_t *addressp) {
+	socklen_t len;
+	isc_result_t result;
+	char strbuf[ISC_STRERRORSIZE];
+
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(addressp != NULL);
+
+	LOCK(&sock->lock);
+
+	if (!sock->bound) {
+		result = ISC_R_NOTBOUND;
+		goto out;
+	}
+
+	result = ISC_R_SUCCESS;
+
+	len = sizeof(addressp->type);
+	if (getsockname(sock->fd, &addressp->type.sa, (void *)&len) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "getsockname: %s", strbuf);
+		result = ISC_R_UNEXPECTED;
+		goto out;
+	}
+	addressp->length = (unsigned int)len;
+
+out:
+	UNLOCK(&sock->lock);
+
+	return (result);
+}
+
+/*
+ * Run through the list of events on this socket, and cancel the ones
+ * queued for task "task" of type "how".  "how" is a bitmask.
+ */
+void
+isc_socket_cancel(isc_socket_t *sock, isc_task_t *task, unsigned int how) {
+	REQUIRE(VALID_SOCKET(sock));
+
+	/*
+	 * Quick exit if there is nothing to do.  Don't even bother locking
+	 * in this case.
+	 */
+	if (how == 0) {
+		return;
+	}
+
+	LOCK(&sock->lock);
+
+	/*
+	 * All of these do the same thing, more or less.
+	 * Each will:
+	 *	o If the internal event is marked as "posted" try to
+	 *	  remove it from the task's queue.  If this fails, mark it
+	 *	  as canceled instead, and let the task clean it up later.
+	 *	o For each I/O request for that task of that type, post
+	 *	  its done event with status of "ISC_R_CANCELED".
+	 *	o Reset any state needed.
+	 */
+	if (((how & ISC_SOCKCANCEL_RECV) != 0) &&
+	    !ISC_LIST_EMPTY(sock->recv_list))
+	{
+		isc_socketevent_t *dev;
+		isc_socketevent_t *next;
+		isc_task_t *current_task;
+
+		dev = ISC_LIST_HEAD(sock->recv_list);
+
+		while (dev != NULL) {
+			current_task = dev->ev_sender;
+			next = ISC_LIST_NEXT(dev, ev_link);
+
+			if ((task == NULL) || (task == current_task)) {
+				dev->result = ISC_R_CANCELED;
+				send_recvdone_event(sock, &dev);
+			}
+			dev = next;
+		}
+	}
+
+	if (((how & ISC_SOCKCANCEL_SEND) != 0) &&
+	    !ISC_LIST_EMPTY(sock->send_list))
+	{
+		isc_socketevent_t *dev;
+		isc_socketevent_t *next;
+		isc_task_t *current_task;
+
+		dev = ISC_LIST_HEAD(sock->send_list);
+
+		while (dev != NULL) {
+			current_task = dev->ev_sender;
+			next = ISC_LIST_NEXT(dev, ev_link);
+
+			if ((task == NULL) || (task == current_task)) {
+				dev->result = ISC_R_CANCELED;
+				send_senddone_event(sock, &dev);
+			}
+			dev = next;
+		}
+	}
+
+	if (((how & ISC_SOCKCANCEL_ACCEPT) != 0) &&
+	    !ISC_LIST_EMPTY(sock->accept_list))
+	{
+		isc_socket_newconnev_t *dev;
+		isc_socket_newconnev_t *next;
+		isc_task_t *current_task;
+
+		dev = ISC_LIST_HEAD(sock->accept_list);
+		while (dev != NULL) {
+			current_task = dev->ev_sender;
+			next = ISC_LIST_NEXT(dev, ev_link);
+
+			if ((task == NULL) || (task == current_task)) {
+				ISC_LIST_UNLINK(sock->accept_list, dev,
+						ev_link);
+
+				isc_refcount_decrementz(
+					&NEWCONNSOCK(dev)->references);
+				free_socket((isc_socket_t **)&dev->newsocket);
+
+				dev->result = ISC_R_CANCELED;
+				dev->ev_sender = sock;
+				isc_task_sendtoanddetach(&current_task,
+							 ISC_EVENT_PTR(&dev),
+							 sock->threadid);
+			}
+
+			dev = next;
+		}
+	}
+
+	if (((how & ISC_SOCKCANCEL_CONNECT) != 0) &&
+	    !ISC_LIST_EMPTY(sock->connect_list))
+	{
+		isc_socket_connev_t *dev;
+		isc_socket_connev_t *next;
+		isc_task_t *current_task;
+
+		INSIST(sock->connecting);
+		sock->connecting = 0;
+
+		dev = ISC_LIST_HEAD(sock->connect_list);
+
+		while (dev != NULL) {
+			current_task = dev->ev_sender;
+			next = ISC_LIST_NEXT(dev, ev_link);
+
+			if ((task == NULL) || (task == current_task)) {
+				dev->result = ISC_R_CANCELED;
+				send_connectdone_event(sock, &dev);
+			}
+			dev = next;
+		}
+	}
+
+	UNLOCK(&sock->lock);
+}
+
+isc_sockettype_t
+isc_socket_gettype(isc_socket_t *sock) {
+	REQUIRE(VALID_SOCKET(sock));
+
+	return (sock->type);
+}
+
+void
+isc_socket_ipv6only(isc_socket_t *sock, bool yes) {
+#if defined(IPV6_V6ONLY) && !defined(__OpenBSD__)
+	int onoff = yes ? 1 : 0;
+#else  /* if defined(IPV6_V6ONLY) */
+	UNUSED(yes);
+	UNUSED(sock);
+#endif /* if defined(IPV6_V6ONLY) */
+
+	REQUIRE(VALID_SOCKET(sock));
+	INSIST(!sock->dupped);
+
+#if defined(IPV6_V6ONLY) && !defined(__OpenBSD__)
+	if (sock->pf == AF_INET6) {
+		if (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_V6ONLY,
+			       (void *)&onoff, sizeof(int)) < 0)
+		{
+			char strbuf[ISC_STRERRORSIZE];
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, IPV6_V6ONLY) failed: "
+					 "%s",
+					 sock->fd, strbuf);
+		}
+	}
+#endif /* ifdef IPV6_V6ONLY */
+}
+
+static void
+setdscp(isc_socket_t *sock, isc_dscp_t dscp) {
+#if defined(IP_TOS) || defined(IPV6_TCLASS)
+	int value = dscp << 2;
+#endif /* if defined(IP_TOS) || defined(IPV6_TCLASS) */
+
+	sock->dscp = dscp;
+
+#ifdef IP_TOS
+	if (sock->pf == AF_INET) {
+		if (setsockopt(sock->fd, IPPROTO_IP, IP_TOS, (void *)&value,
+			       sizeof(value)) < 0)
+		{
+			char strbuf[ISC_STRERRORSIZE];
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, IP_TOS, %.02x) "
+					 "failed: %s",
+					 sock->fd, value >> 2, strbuf);
+		}
+	}
+#endif /* ifdef IP_TOS */
+#ifdef IPV6_TCLASS
+	if (sock->pf == AF_INET6) {
+		if (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_TCLASS,
+			       (void *)&value, sizeof(value)) < 0)
+		{
+			char strbuf[ISC_STRERRORSIZE];
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "setsockopt(%d, IPV6_TCLASS, %.02x) "
+					 "failed: %s",
+					 sock->fd, dscp >> 2, strbuf);
+		}
+	}
+#endif /* ifdef IPV6_TCLASS */
+}
+
+void
+isc_socket_dscp(isc_socket_t *sock, isc_dscp_t dscp) {
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(dscp < 0x40);
+
+#if !defined(IP_TOS) && !defined(IPV6_TCLASS)
+	UNUSED(dscp);
+#else  /* if !defined(IP_TOS) && !defined(IPV6_TCLASS) */
+	if (dscp < 0) {
+		return;
+	}
+
+	/* The DSCP value must not be changed once it has been set. */
+	if (isc_dscp_check_value != -1) {
+		INSIST(dscp == isc_dscp_check_value);
+	}
+#endif /* if !defined(IP_TOS) && !defined(IPV6_TCLASS) */
+
+#ifdef notyet
+	REQUIRE(!sock->dupped);
+#endif /* ifdef notyet */
+
+	setdscp(sock, dscp);
+}
+
+isc_socketevent_t *
+isc_socket_socketevent(isc_mem_t *mctx, void *sender, isc_eventtype_t eventtype,
+		       isc_taskaction_t action, void *arg) {
+	return (allocate_socketevent(mctx, sender, eventtype, action, arg));
+}
+
+void
+isc_socket_setname(isc_socket_t *sock, const char *name, void *tag) {
+	/*
+	 * Name 'sock'.
+	 */
+
+	REQUIRE(VALID_SOCKET(sock));
+
+	LOCK(&sock->lock);
+	strlcpy(sock->name, name, sizeof(sock->name));
+	sock->tag = tag;
+	UNLOCK(&sock->lock);
+}
+
+const char *
+isc_socket_getname(isc_socket_t *sock) {
+	return (sock->name);
+}
+
+void *
+isc_socket_gettag(isc_socket_t *sock) {
+	return (sock->tag);
+}
+
+int
+isc_socket_getfd(isc_socket_t *sock) {
+	return ((short)sock->fd);
+}
+
+static isc_once_t hasreuseport_once = ISC_ONCE_INIT;
+static bool hasreuseport = false;
+
+static void
+init_hasreuseport() {
+/*
+ * SO_REUSEPORT works very differently on *BSD and on Linux (because why not).
+ * We only want to use it on Linux, if it's available. On BSD we want to dup()
+ * sockets instead of re-binding them.
+ */
+#if (defined(SO_REUSEPORT) && defined(__linux__)) || \
+	(defined(SO_REUSEPORT_LB) && defined(__FreeBSD_kernel__))
+	int sock, yes = 1;
+	sock = socket(AF_INET, SOCK_DGRAM, 0);
+	if (sock < 0) {
+		sock = socket(AF_INET6, SOCK_DGRAM, 0);
+		if (sock < 0) {
+			return;
+		}
+	}
+	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&yes,
+		       sizeof(yes)) < 0)
+	{
+		close(sock);
+		return;
+#if defined(__FreeBSD_kernel__)
+	} else if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT_LB, (void *)&yes,
+			      sizeof(yes)) < 0)
+#else  /* if defined(__FreeBSD_kernel__) */
+	} else if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, (void *)&yes,
+			      sizeof(yes)) < 0)
+#endif /* if defined(__FreeBSD_kernel__) */
+	{
+		close(sock);
+		return;
+	}
+	hasreuseport = true;
+	close(sock);
+#endif /* if (defined(SO_REUSEPORT) && defined(__linux__)) || \
+	* (defined(SO_REUSEPORT_LB) && defined(__FreeBSD_kernel__)) */
+}
+
+bool
+isc_socket_hasreuseport() {
+	RUNTIME_CHECK(isc_once_do(&hasreuseport_once, init_hasreuseport) ==
+		      ISC_R_SUCCESS);
+	return (hasreuseport);
+}
+
+#if defined(HAVE_LIBXML2) || defined(HAVE_JSON_C)
+static const char *
+_socktype(isc_sockettype_t type) {
+	switch (type) {
+	case isc_sockettype_udp:
+		return ("udp");
+	case isc_sockettype_tcp:
+		return ("tcp");
+	case isc_sockettype_unix:
+		return ("unix");
+	default:
+		return ("not-initialized");
+	}
+}
+#endif /* if defined(HAVE_LIBXML2) || defined(HAVE_JSON_C) */
+
+#ifdef HAVE_LIBXML2
+#define TRY0(a)                     \
+	do {                        \
+		xmlrc = (a);        \
+		if (xmlrc < 0)      \
+			goto error; \
+	} while (0)
+int
+isc_socketmgr_renderxml(isc_socketmgr_t *mgr, void *writer0) {
+	isc_socket_t *sock = NULL;
+	char peerbuf[ISC_SOCKADDR_FORMATSIZE];
+	isc_sockaddr_t addr;
+	socklen_t len;
+	int xmlrc;
+	xmlTextWriterPtr writer = (xmlTextWriterPtr)writer0;
+
+	LOCK(&mgr->lock);
+
+	TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "sockets"));
+	sock = ISC_LIST_HEAD(mgr->socklist);
+	while (sock != NULL) {
+		LOCK(&sock->lock);
+		TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "socket"));
+
+		TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "id"));
+		TRY0(xmlTextWriterWriteFormatString(writer, "%p", sock));
+		TRY0(xmlTextWriterEndElement(writer));
+
+		if (sock->name[0] != 0) {
+			TRY0(xmlTextWriterStartElement(writer,
+						       ISC_XMLCHAR "name"));
+			TRY0(xmlTextWriterWriteFormatString(writer, "%s",
+							    sock->name));
+			TRY0(xmlTextWriterEndElement(writer)); /* name */
+		}
+
+		TRY0(xmlTextWriterStartElement(writer,
+					       ISC_XMLCHAR "references"));
+		TRY0(xmlTextWriterWriteFormatString(
+			writer, "%d",
+			(int)isc_refcount_current(&sock->references)));
+		TRY0(xmlTextWriterEndElement(writer));
+
+		TRY0(xmlTextWriterWriteElement(
+			writer, ISC_XMLCHAR "type",
+			ISC_XMLCHAR _socktype(sock->type)));
+
+		if (sock->connected) {
+			isc_sockaddr_format(&sock->peer_address, peerbuf,
+					    sizeof(peerbuf));
+			TRY0(xmlTextWriterWriteElement(
+				writer, ISC_XMLCHAR "peer-address",
+				ISC_XMLCHAR peerbuf));
+		}
+
+		len = sizeof(addr);
+		if (getsockname(sock->fd, &addr.type.sa, (void *)&len) == 0) {
+			isc_sockaddr_format(&addr, peerbuf, sizeof(peerbuf));
+			TRY0(xmlTextWriterWriteElement(
+				writer, ISC_XMLCHAR "local-address",
+				ISC_XMLCHAR peerbuf));
+		}
+
+		TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "states"));
+		if (sock->listener) {
+			TRY0(xmlTextWriterWriteElement(writer,
+						       ISC_XMLCHAR "state",
+						       ISC_XMLCHAR "listener"));
+		}
+		if (sock->connected) {
+			TRY0(xmlTextWriterWriteElement(
+				writer, ISC_XMLCHAR "state",
+				ISC_XMLCHAR "connected"));
+		}
+		if (sock->connecting) {
+			TRY0(xmlTextWriterWriteElement(
+				writer, ISC_XMLCHAR "state",
+				ISC_XMLCHAR "connecting"));
+		}
+		if (sock->bound) {
+			TRY0(xmlTextWriterWriteElement(writer,
+						       ISC_XMLCHAR "state",
+						       ISC_XMLCHAR "bound"));
+		}
+
+		TRY0(xmlTextWriterEndElement(writer)); /* states */
+
+		TRY0(xmlTextWriterEndElement(writer)); /* socket */
+
+		UNLOCK(&sock->lock);
+		sock = ISC_LIST_NEXT(sock, link);
+	}
+	TRY0(xmlTextWriterEndElement(writer)); /* sockets */
+
+error:
+	if (sock != NULL) {
+		UNLOCK(&sock->lock);
+	}
+
+	UNLOCK(&mgr->lock);
+
+	return (xmlrc);
+}
+#endif /* HAVE_LIBXML2 */
+
+#ifdef HAVE_JSON_C
+#define CHECKMEM(m)                              \
+	do {                                     \
+		if (m == NULL) {                 \
+			result = ISC_R_NOMEMORY; \
+			goto error;              \
+		}                                \
+	} while (0)
+
+isc_result_t
+isc_socketmgr_renderjson(isc_socketmgr_t *mgr, void *stats0) {
+	isc_result_t result = ISC_R_SUCCESS;
+	isc_socket_t *sock = NULL;
+	char peerbuf[ISC_SOCKADDR_FORMATSIZE];
+	isc_sockaddr_t addr;
+	socklen_t len;
+	json_object *obj, *array = json_object_new_array();
+	json_object *stats = (json_object *)stats0;
+
+	CHECKMEM(array);
+
+	LOCK(&mgr->lock);
+
+	sock = ISC_LIST_HEAD(mgr->socklist);
+	while (sock != NULL) {
+		json_object *states, *entry = json_object_new_object();
+		char buf[255];
+
+		CHECKMEM(entry);
+		json_object_array_add(array, entry);
+
+		LOCK(&sock->lock);
+
+		snprintf(buf, sizeof(buf), "%p", sock);
+		obj = json_object_new_string(buf);
+		CHECKMEM(obj);
+		json_object_object_add(entry, "id", obj);
+
+		if (sock->name[0] != 0) {
+			obj = json_object_new_string(sock->name);
+			CHECKMEM(obj);
+			json_object_object_add(entry, "name", obj);
+		}
+
+		obj = json_object_new_int(
+			(int)isc_refcount_current(&sock->references));
+		CHECKMEM(obj);
+		json_object_object_add(entry, "references", obj);
+
+		obj = json_object_new_string(_socktype(sock->type));
+		CHECKMEM(obj);
+		json_object_object_add(entry, "type", obj);
+
+		if (sock->connected) {
+			isc_sockaddr_format(&sock->peer_address, peerbuf,
+					    sizeof(peerbuf));
+			obj = json_object_new_string(peerbuf);
+			CHECKMEM(obj);
+			json_object_object_add(entry, "peer-address", obj);
+		}
+
+		len = sizeof(addr);
+		if (getsockname(sock->fd, &addr.type.sa, (void *)&len) == 0) {
+			isc_sockaddr_format(&addr, peerbuf, sizeof(peerbuf));
+			obj = json_object_new_string(peerbuf);
+			CHECKMEM(obj);
+			json_object_object_add(entry, "local-address", obj);
+		}
+
+		states = json_object_new_array();
+		CHECKMEM(states);
+		json_object_object_add(entry, "states", states);
+
+		if (sock->listener) {
+			obj = json_object_new_string("listener");
+			CHECKMEM(obj);
+			json_object_array_add(states, obj);
+		}
+
+		if (sock->connected) {
+			obj = json_object_new_string("connected");
+			CHECKMEM(obj);
+			json_object_array_add(states, obj);
+		}
+
+		if (sock->connecting) {
+			obj = json_object_new_string("connecting");
+			CHECKMEM(obj);
+			json_object_array_add(states, obj);
+		}
+
+		if (sock->bound) {
+			obj = json_object_new_string("bound");
+			CHECKMEM(obj);
+			json_object_array_add(states, obj);
+		}
+
+		UNLOCK(&sock->lock);
+		sock = ISC_LIST_NEXT(sock, link);
+	}
+
+	json_object_object_add(stats, "sockets", array);
+	array = NULL;
+	result = ISC_R_SUCCESS;
+
+error:
+	if (array != NULL) {
+		json_object_put(array);
+	}
+
+	if (sock != NULL) {
+		UNLOCK(&sock->lock);
+	}
+
+	UNLOCK(&mgr->lock);
+
+	return (result);
+}
+#endif /* HAVE_JSON_C */