Adding upstream version 2.9.5.upstream/2.9.5

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

1 files changed, 834 insertions, 0 deletions

diff --git a/src/proto_tcp.c b/src/proto_tcp.c
new file mode 100644
index 0000000..45ce27f
--- /dev/null
+++ b/src/proto_tcp.c
@@ -0,0 +1,834 @@
+/*
+ * AF_INET/AF_INET6 SOCK_STREAM protocol layer (tcp)
+ *
+ * Copyright 2000-2013 Willy Tarreau <w@1wt.eu>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include <netinet/tcp.h>
+#include <netinet/in.h>
+
+#include <haproxy/api.h>
+#include <haproxy/arg.h>
+#include <haproxy/connection.h>
+#include <haproxy/errors.h>
+#include <haproxy/fd.h>
+#include <haproxy/global.h>
+#include <haproxy/list.h>
+#include <haproxy/listener.h>
+#include <haproxy/log.h>
+#include <haproxy/namespace.h>
+#include <haproxy/port_range.h>
+#include <haproxy/proto_tcp.h>
+#include <haproxy/protocol.h>
+#include <haproxy/proxy-t.h>
+#include <haproxy/sock.h>
+#include <haproxy/sock_inet.h>
+#include <haproxy/tools.h>
+
+
+static int tcp_bind_listener(struct listener *listener, char *errmsg, int errlen);
+static int tcp_suspend_receiver(struct receiver *rx);
+static int tcp_resume_receiver(struct receiver *rx);
+static void tcp_enable_listener(struct listener *listener);
+static void tcp_disable_listener(struct listener *listener);
+
+/* Note: must not be declared <const> as its list will be overwritten */
+struct protocol proto_tcpv4 = {
+	.name           = "tcpv4",
+
+	/* connection layer */
+	.xprt_type      = PROTO_TYPE_STREAM,
+	.listen         = tcp_bind_listener,
+	.enable         = tcp_enable_listener,
+	.disable        = tcp_disable_listener,
+	.add            = default_add_listener,
+	.unbind         = default_unbind_listener,
+	.suspend        = default_suspend_listener,
+	.resume         = default_resume_listener,
+	.accept_conn    = sock_accept_conn,
+	.ctrl_init      = sock_conn_ctrl_init,
+	.ctrl_close     = sock_conn_ctrl_close,
+	.connect        = tcp_connect_server,
+	.drain          = sock_drain,
+	.check_events   = sock_check_events,
+	.ignore_events  = sock_ignore_events,
+
+	/* binding layer */
+	.rx_suspend     = tcp_suspend_receiver,
+	.rx_resume      = tcp_resume_receiver,
+
+	/* address family */
+	.fam            = &proto_fam_inet4,
+
+	/* socket layer */
+	.proto_type     = PROTO_TYPE_STREAM,
+	.sock_type      = SOCK_STREAM,
+	.sock_prot      = IPPROTO_TCP,
+	.rx_enable      = sock_enable,
+	.rx_disable     = sock_disable,
+	.rx_unbind      = sock_unbind,
+	.rx_listening   = sock_accepting_conn,
+	.default_iocb   = sock_accept_iocb,
+	.receivers      = LIST_HEAD_INIT(proto_tcpv4.receivers),
+	.nb_receivers   = 0,
+#ifdef SO_REUSEPORT
+	.flags          = PROTO_F_REUSEPORT_SUPPORTED,
+#endif
+};
+
+INITCALL1(STG_REGISTER, protocol_register, &proto_tcpv4);
+
+/* Note: must not be declared <const> as its list will be overwritten */
+struct protocol proto_tcpv6 = {
+	.name           = "tcpv6",
+
+	/* connection layer */
+	.xprt_type      = PROTO_TYPE_STREAM,
+	.listen         = tcp_bind_listener,
+	.enable         = tcp_enable_listener,
+	.disable        = tcp_disable_listener,
+	.add            = default_add_listener,
+	.unbind         = default_unbind_listener,
+	.suspend        = default_suspend_listener,
+	.resume         = default_resume_listener,
+	.accept_conn    = sock_accept_conn,
+	.ctrl_init      = sock_conn_ctrl_init,
+	.ctrl_close     = sock_conn_ctrl_close,
+	.connect        = tcp_connect_server,
+	.drain          = sock_drain,
+	.check_events   = sock_check_events,
+	.ignore_events  = sock_ignore_events,
+
+	/* binding layer */
+	.rx_suspend     = tcp_suspend_receiver,
+	.rx_resume      = tcp_resume_receiver,
+
+	/* address family */
+	.fam            = &proto_fam_inet6,
+
+	/* socket layer */
+	.proto_type     = PROTO_TYPE_STREAM,
+	.sock_type      = SOCK_STREAM,
+	.sock_prot      = IPPROTO_TCP,
+	.rx_enable      = sock_enable,
+	.rx_disable     = sock_disable,
+	.rx_unbind      = sock_unbind,
+	.rx_listening   = sock_accepting_conn,
+	.default_iocb   = sock_accept_iocb,
+	.receivers      = LIST_HEAD_INIT(proto_tcpv6.receivers),
+	.nb_receivers   = 0,
+#ifdef SO_REUSEPORT
+	.flags          = PROTO_F_REUSEPORT_SUPPORTED,
+#endif
+};
+
+INITCALL1(STG_REGISTER, protocol_register, &proto_tcpv6);
+
+/* Binds ipv4/ipv6 address <local> to socket <fd>, unless <flags> is set, in which
+ * case we try to bind <remote>. <flags> is a 2-bit field consisting of :
+ *  - 0 : ignore remote address (may even be a NULL pointer)
+ *  - 1 : use provided address
+ *  - 2 : use provided port
+ *  - 3 : use both
+ *
+ * The function supports multiple foreign binding methods :
+ *   - linux_tproxy: we directly bind to the foreign address
+ * The second one can be used as a fallback for the first one.
+ * This function returns 0 when everything's OK, 1 if it could not bind, to the
+ * local address, 2 if it could not bind to the foreign address.
+ */
+int tcp_bind_socket(int fd, int flags, struct sockaddr_storage *local, struct sockaddr_storage *remote)
+{
+	struct sockaddr_storage bind_addr;
+	int foreign_ok = 0;
+	int ret;
+	static THREAD_LOCAL int ip_transp_working = 1;
+	static THREAD_LOCAL int ip6_transp_working = 1;
+
+	switch (local->ss_family) {
+	case AF_INET:
+		if (flags && ip_transp_working) {
+			/* This deserves some explanation. Some platforms will support
+			 * multiple combinations of certain methods, so we try the
+			 * supported ones until one succeeds.
+			 */
+			if (sock_inet4_make_foreign(fd))
+				foreign_ok = 1;
+			else
+				ip_transp_working = 0;
+		}
+		break;
+	case AF_INET6:
+		if (flags && ip6_transp_working) {
+			if (sock_inet6_make_foreign(fd))
+				foreign_ok = 1;
+			else
+				ip6_transp_working = 0;
+		}
+		break;
+	}
+
+	if (flags) {
+		memset(&bind_addr, 0, sizeof(bind_addr));
+		bind_addr.ss_family = remote->ss_family;
+		switch (remote->ss_family) {
+		case AF_INET:
+			if (flags & 1)
+				((struct sockaddr_in *)&bind_addr)->sin_addr = ((struct sockaddr_in *)remote)->sin_addr;
+			if (flags & 2)
+				((struct sockaddr_in *)&bind_addr)->sin_port = ((struct sockaddr_in *)remote)->sin_port;
+			break;
+		case AF_INET6:
+			if (flags & 1)
+				((struct sockaddr_in6 *)&bind_addr)->sin6_addr = ((struct sockaddr_in6 *)remote)->sin6_addr;
+			if (flags & 2)
+				((struct sockaddr_in6 *)&bind_addr)->sin6_port = ((struct sockaddr_in6 *)remote)->sin6_port;
+			break;
+		default:
+			/* we don't want to try to bind to an unknown address family */
+			foreign_ok = 0;
+		}
+	}
+
+	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+	if (foreign_ok) {
+		if (is_inet_addr(&bind_addr)) {
+			ret = bind(fd, (struct sockaddr *)&bind_addr, get_addr_len(&bind_addr));
+			if (ret < 0)
+				return 2;
+		}
+	}
+	else {
+		if (is_inet_addr(local)) {
+			ret = bind(fd, (struct sockaddr *)local, get_addr_len(local));
+			if (ret < 0)
+				return 1;
+		}
+	}
+
+	if (!flags)
+		return 0;
+
+	if (!foreign_ok)
+		/* we could not bind to a foreign address */
+		return 2;
+
+	return 0;
+}
+
+/*
+ * This function initiates a TCP connection establishment to the target assigned
+ * to connection <conn> using (si->{target,dst}). A source address may be
+ * pointed to by conn->src in case of transparent proxying. Normal source
+ * bind addresses are still determined locally (due to the possible need of a
+ * source port). conn->target may point either to a valid server or to a backend,
+ * depending on conn->target. Only OBJ_TYPE_PROXY and OBJ_TYPE_SERVER are
+ * supported. The <data> parameter is a boolean indicating whether there are data
+ * waiting for being sent or not, in order to adjust data write polling and on
+ * some platforms, the ability to avoid an empty initial ACK. The <flags> argument
+ * allows the caller to force using a delayed ACK when establishing the connection
+ *   - 0 = no delayed ACK unless data are advertised and backend has tcp-smart-connect
+ *   - CONNECT_DELACK_SMART_CONNECT = delayed ACK if backend has tcp-smart-connect, regardless of data
+ *   - CONNECT_DELACK_ALWAYS = delayed ACK regardless of backend options
+ *
+ * Note that a pending send_proxy message accounts for data.
+ *
+ * It can return one of :
+ *  - SF_ERR_NONE if everything's OK
+ *  - SF_ERR_SRVTO if there are no more servers
+ *  - SF_ERR_SRVCL if the connection was refused by the server
+ *  - SF_ERR_PRXCOND if the connection has been limited by the proxy (maxconn)
+ *  - SF_ERR_RESOURCE if a system resource is lacking (eg: fd limits, ports, ...)
+ *  - SF_ERR_INTERNAL for any other purely internal errors
+ * Additionally, in the case of SF_ERR_RESOURCE, an emergency log will be emitted.
+ *
+ * The connection's fd is inserted only when SF_ERR_NONE is returned, otherwise
+ * it's invalid and the caller has nothing to do.
+ */
+
+int tcp_connect_server(struct connection *conn, int flags)
+{
+	int fd;
+	struct server *srv;
+	struct proxy *be;
+	struct conn_src *src;
+	int use_fastopen = 0;
+	struct sockaddr_storage *addr;
+
+	BUG_ON(!conn->dst);
+
+	conn->flags |= CO_FL_WAIT_L4_CONN; /* connection in progress */
+
+	switch (obj_type(conn->target)) {
+	case OBJ_TYPE_PROXY:
+		be = __objt_proxy(conn->target);
+		srv = NULL;
+		break;
+	case OBJ_TYPE_SERVER:
+		srv = __objt_server(conn->target);
+		be = srv->proxy;
+		/* Make sure we check that we have data before activating
+		 * TFO, or we could trigger a kernel issue whereby after
+		 * a successful connect() == 0, any subsequent connect()
+		 * will return EINPROGRESS instead of EISCONN.
+		 */
+		use_fastopen = (srv->flags & SRV_F_FASTOPEN) &&
+		               ((flags & (CONNECT_CAN_USE_TFO | CONNECT_HAS_DATA)) ==
+				(CONNECT_CAN_USE_TFO | CONNECT_HAS_DATA));
+		break;
+	default:
+		conn->flags |= CO_FL_ERROR;
+		return SF_ERR_INTERNAL;
+	}
+
+	fd = conn->handle.fd = sock_create_server_socket(conn);
+
+	if (fd == -1) {
+		qfprintf(stderr, "Cannot get a server socket.\n");
+
+		if (errno == ENFILE) {
+			conn->err_code = CO_ER_SYS_FDLIM;
+			send_log(be, LOG_EMERG,
+				 "Proxy %s reached system FD limit (maxsock=%d). Please check system tunables.\n",
+				 be->id, global.maxsock);
+		}
+		else if (errno == EMFILE) {
+			conn->err_code = CO_ER_PROC_FDLIM;
+			send_log(be, LOG_EMERG,
+				 "Proxy %s reached process FD limit (maxsock=%d). Please check 'ulimit-n' and restart.\n",
+				 be->id, global.maxsock);
+		}
+		else if (errno == ENOBUFS || errno == ENOMEM) {
+			conn->err_code = CO_ER_SYS_MEMLIM;
+			send_log(be, LOG_EMERG,
+				 "Proxy %s reached system memory limit (maxsock=%d). Please check system tunables.\n",
+				 be->id, global.maxsock);
+		}
+		else if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) {
+			conn->err_code = CO_ER_NOPROTO;
+		}
+		else
+			conn->err_code = CO_ER_SOCK_ERR;
+
+		/* this is a resource error */
+		conn->flags |= CO_FL_ERROR;
+		return SF_ERR_RESOURCE;
+	}
+
+	if (fd >= global.maxsock) {
+		/* do not log anything there, it's a normal condition when this option
+		 * is used to serialize connections to a server !
+		 */
+		ha_alert("socket(): not enough free sockets. Raise -n argument. Giving up.\n");
+		close(fd);
+		conn->err_code = CO_ER_CONF_FDLIM;
+		conn->flags |= CO_FL_ERROR;
+		return SF_ERR_PRXCOND; /* it is a configuration limit */
+	}
+
+	if (fd_set_nonblock(fd) == -1 ||
+	    (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)) == -1)) {
+		qfprintf(stderr,"Cannot set client socket to non blocking mode.\n");
+		close(fd);
+		conn->err_code = CO_ER_SOCK_ERR;
+		conn->flags |= CO_FL_ERROR;
+		return SF_ERR_INTERNAL;
+	}
+
+	if (master == 1 && fd_set_cloexec(fd) == -1) {
+		ha_alert("Cannot set CLOEXEC on client socket.\n");
+		close(fd);
+		conn->err_code = CO_ER_SOCK_ERR;
+		conn->flags |= CO_FL_ERROR;
+		return SF_ERR_INTERNAL;
+	}
+
+	if (be->options & PR_O_TCP_SRV_KA) {
+		setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof(one));
+
+#ifdef TCP_KEEPCNT
+		if (be->srvtcpka_cnt)
+			setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, &be->srvtcpka_cnt, sizeof(be->srvtcpka_cnt));
+#endif
+
+#ifdef TCP_KEEPIDLE
+		if (be->srvtcpka_idle)
+			setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &be->srvtcpka_idle, sizeof(be->srvtcpka_idle));
+#endif
+
+#ifdef TCP_KEEPINTVL
+		if (be->srvtcpka_intvl)
+			setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, &be->srvtcpka_intvl, sizeof(be->srvtcpka_intvl));
+#endif
+	}
+
+	/* allow specific binding :
+	 * - server-specific at first
+	 * - proxy-specific next
+	 */
+	if (srv && srv->conn_src.opts & CO_SRC_BIND)
+		src = &srv->conn_src;
+	else if (be->conn_src.opts & CO_SRC_BIND)
+		src = &be->conn_src;
+	else
+		src = NULL;
+
+	if (src) {
+		int ret, flags = 0;
+
+		if (conn->src && is_inet_addr(conn->src)) {
+			switch (src->opts & CO_SRC_TPROXY_MASK) {
+			case CO_SRC_TPROXY_CLI:
+			case CO_SRC_TPROXY_ADDR:
+				flags = 3;
+				break;
+			case CO_SRC_TPROXY_CIP:
+			case CO_SRC_TPROXY_DYN:
+				flags = 1;
+				break;
+			}
+		}
+
+#ifdef SO_BINDTODEVICE
+		/* Note: this might fail if not CAP_NET_RAW */
+		if (src->iface_name)
+			setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, src->iface_name, src->iface_len + 1);
+#endif
+
+		if (src->sport_range) {
+			int attempts = 10; /* should be more than enough to find a spare port */
+			struct sockaddr_storage sa;
+
+			ret = 1;
+			memcpy(&sa, &src->source_addr, sizeof(sa));
+
+			do {
+				/* note: in case of retry, we may have to release a previously
+				 * allocated port, hence this loop's construct.
+				 */
+				port_range_release_port(fdinfo[fd].port_range, fdinfo[fd].local_port);
+				fdinfo[fd].port_range = NULL;
+
+				if (!attempts)
+					break;
+				attempts--;
+
+				fdinfo[fd].local_port = port_range_alloc_port(src->sport_range);
+				if (!fdinfo[fd].local_port) {
+					conn->err_code = CO_ER_PORT_RANGE;
+					break;
+				}
+
+				fdinfo[fd].port_range = src->sport_range;
+				set_host_port(&sa, fdinfo[fd].local_port);
+
+				ret = tcp_bind_socket(fd, flags, &sa, conn->src);
+				if (ret != 0)
+					conn->err_code = CO_ER_CANT_BIND;
+			} while (ret != 0); /* binding NOK */
+		}
+		else {
+#ifdef IP_BIND_ADDRESS_NO_PORT
+			static THREAD_LOCAL int bind_address_no_port = 1;
+			setsockopt(fd, IPPROTO_IP, IP_BIND_ADDRESS_NO_PORT, (const void *) &bind_address_no_port, sizeof(int));
+#endif
+			ret = tcp_bind_socket(fd, flags, &src->source_addr, conn->src);
+			if (ret != 0)
+				conn->err_code = CO_ER_CANT_BIND;
+		}
+
+		if (unlikely(ret != 0)) {
+			port_range_release_port(fdinfo[fd].port_range, fdinfo[fd].local_port);
+			fdinfo[fd].port_range = NULL;
+			close(fd);
+
+			if (ret == 1) {
+				ha_alert("Cannot bind to source address before connect() for backend %s. Aborting.\n",
+					 be->id);
+				send_log(be, LOG_EMERG,
+					 "Cannot bind to source address before connect() for backend %s.\n",
+					 be->id);
+			} else {
+				ha_alert("Cannot bind to tproxy source address before connect() for backend %s. Aborting.\n",
+					 be->id);
+				send_log(be, LOG_EMERG,
+					 "Cannot bind to tproxy source address before connect() for backend %s.\n",
+					 be->id);
+			}
+			conn->flags |= CO_FL_ERROR;
+			return SF_ERR_RESOURCE;
+		}
+	}
+
+#if defined(TCP_QUICKACK)
+	/* disabling tcp quick ack now allows the first request to leave the
+	 * machine with the first ACK. We only do this if there are pending
+	 * data in the buffer.
+	 */
+	if (flags & (CONNECT_DELACK_ALWAYS) ||
+	    ((flags & CONNECT_DELACK_SMART_CONNECT ||
+	      (flags & CONNECT_HAS_DATA) || conn->send_proxy_ofs) &&
+	     (be->options2 & PR_O2_SMARTCON)))
+                setsockopt(fd, IPPROTO_TCP, TCP_QUICKACK, &zero, sizeof(zero));
+#endif
+
+#ifdef TCP_USER_TIMEOUT
+	/* there is not much more we can do here when it fails, it's still minor */
+	if (srv && srv->tcp_ut)
+		setsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT, &srv->tcp_ut, sizeof(srv->tcp_ut));
+#endif
+
+	if (use_fastopen) {
+#if defined(TCP_FASTOPEN_CONNECT)
+                setsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, &one, sizeof(one));
+#endif
+	}
+	if (global.tune.server_sndbuf)
+                setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &global.tune.server_sndbuf, sizeof(global.tune.server_sndbuf));
+
+	if (global.tune.server_rcvbuf)
+                setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &global.tune.server_rcvbuf, sizeof(global.tune.server_rcvbuf));
+
+	addr = (conn->flags & CO_FL_SOCKS4) ? &srv->socks4_addr : conn->dst;
+	if (connect(fd, (const struct sockaddr *)addr, get_addr_len(addr)) == -1) {
+		if (errno == EINPROGRESS || errno == EALREADY) {
+			/* common case, let's wait for connect status */
+			conn->flags |= CO_FL_WAIT_L4_CONN;
+		}
+		else if (errno == EISCONN) {
+			/* should normally not happen but if so, indicates that it's OK */
+			conn->flags &= ~CO_FL_WAIT_L4_CONN;
+		}
+		else if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EADDRINUSE || errno == EADDRNOTAVAIL) {
+			char *msg;
+			if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EADDRNOTAVAIL) {
+				msg = "no free ports";
+				conn->err_code = CO_ER_FREE_PORTS;
+			}
+			else {
+				msg = "local address already in use";
+				conn->err_code = CO_ER_ADDR_INUSE;
+			}
+
+			qfprintf(stderr,"Connect() failed for backend %s: %s.\n", be->id, msg);
+			port_range_release_port(fdinfo[fd].port_range, fdinfo[fd].local_port);
+			fdinfo[fd].port_range = NULL;
+			close(fd);
+			send_log(be, LOG_ERR, "Connect() failed for backend %s: %s.\n", be->id, msg);
+			conn->flags |= CO_FL_ERROR;
+			return SF_ERR_RESOURCE;
+		} else if (errno == ETIMEDOUT) {
+			//qfprintf(stderr,"Connect(): ETIMEDOUT");
+			port_range_release_port(fdinfo[fd].port_range, fdinfo[fd].local_port);
+			fdinfo[fd].port_range = NULL;
+			close(fd);
+			conn->err_code = CO_ER_SOCK_ERR;
+			conn->flags |= CO_FL_ERROR;
+			return SF_ERR_SRVTO;
+		} else {
+			// (errno == ECONNREFUSED || errno == ENETUNREACH || errno == EACCES || errno == EPERM)
+			//qfprintf(stderr,"Connect(): %d", errno);
+			port_range_release_port(fdinfo[fd].port_range, fdinfo[fd].local_port);
+			fdinfo[fd].port_range = NULL;
+			close(fd);
+			conn->err_code = CO_ER_SOCK_ERR;
+			conn->flags |= CO_FL_ERROR;
+			return SF_ERR_SRVCL;
+		}
+	}
+	else {
+		/* connect() == 0, this is great! */
+		conn->flags &= ~CO_FL_WAIT_L4_CONN;
+	}
+
+	conn_ctrl_init(conn);       /* registers the FD */
+	HA_ATOMIC_OR(&fdtab[fd].state, FD_LINGER_RISK);  /* close hard if needed */
+
+	if (conn->flags & CO_FL_WAIT_L4_CONN) {
+		fd_want_send(fd);
+		fd_cant_send(fd);
+		fd_cant_recv(fd);
+	}
+
+	return SF_ERR_NONE;  /* connection is OK */
+}
+
+/* This function tries to bind a TCPv4/v6 listener. It may return a warning or
+ * an error message in <errmsg> if the message is at most <errlen> bytes long
+ * (including '\0'). Note that <errmsg> may be NULL if <errlen> is also zero.
+ * The return value is composed from ERR_ABORT, ERR_WARN,
+ * ERR_ALERT, ERR_RETRYABLE and ERR_FATAL. ERR_NONE indicates that everything
+ * was alright and that no message was returned. ERR_RETRYABLE means that an
+ * error occurred but that it may vanish after a retry (eg: port in use), and
+ * ERR_FATAL indicates a non-fixable error. ERR_WARN and ERR_ALERT do not alter
+ * the meaning of the error, but just indicate that a message is present which
+ * should be displayed with the respective level. Last, ERR_ABORT indicates
+ * that it's pointless to try to start other listeners. No error message is
+ * returned if errlen is NULL.
+ */
+int tcp_bind_listener(struct listener *listener, char *errmsg, int errlen)
+{
+	int fd, err;
+	int ready;
+	struct buffer *msg = alloc_trash_chunk();
+
+	err = ERR_NONE;
+
+	if (!msg) {
+		if (errlen)
+			snprintf(errmsg, errlen, "out of memory");
+		return ERR_ALERT | ERR_FATAL;
+	}
+
+	/* ensure we never return garbage */
+	if (errlen)
+		*errmsg = 0;
+
+	if (listener->state != LI_ASSIGNED)
+		return ERR_NONE; /* already bound */
+
+	if (!(listener->rx.flags & RX_F_BOUND)) {
+		chunk_appendf(msg, "%sreceiving socket not bound", msg->data ? ", " : "");
+		goto tcp_return;
+	}
+
+	if (listener->rx.flags & RX_F_MUST_DUP)
+		goto done;
+
+	fd = listener->rx.fd;
+
+	if (listener->bind_conf->options & BC_O_NOLINGER)
+		setsockopt(fd, SOL_SOCKET, SO_LINGER, &nolinger, sizeof(struct linger));
+	else {
+		struct linger tmplinger;
+		socklen_t len = sizeof(tmplinger);
+		if (getsockopt(fd, SOL_SOCKET, SO_LINGER, &tmplinger, &len) == 0 &&
+		    (tmplinger.l_onoff == 1 || tmplinger.l_linger == 0)) {
+			tmplinger.l_onoff = 0;
+			tmplinger.l_linger = 0;
+			setsockopt(fd, SOL_SOCKET, SO_LINGER, &tmplinger,
+			    sizeof(tmplinger));
+		}
+	}
+
+#if defined(TCP_MAXSEG)
+	if (listener->bind_conf->maxseg > 0) {
+		if (setsockopt(fd, IPPROTO_TCP, TCP_MAXSEG,
+			       &listener->bind_conf->maxseg, sizeof(listener->bind_conf->maxseg)) == -1) {
+			chunk_appendf(msg, "%scannot set MSS to %d", msg->data ? ", " : "", listener->bind_conf->maxseg);
+			err |= ERR_WARN;
+		}
+	} else {
+		/* we may want to try to restore the default MSS if the socket was inherited */
+		int tmpmaxseg = -1;
+		int defaultmss;
+		socklen_t len = sizeof(tmpmaxseg);
+
+		if (listener->rx.addr.ss_family == AF_INET)
+			defaultmss = sock_inet_tcp_maxseg_default;
+		else
+			defaultmss = sock_inet6_tcp_maxseg_default;
+
+		getsockopt(fd, IPPROTO_TCP, TCP_MAXSEG, &tmpmaxseg, &len);
+		if (defaultmss > 0 &&
+		    tmpmaxseg != defaultmss &&
+		    setsockopt(fd, IPPROTO_TCP, TCP_MAXSEG, &defaultmss, sizeof(defaultmss)) == -1) {
+			chunk_appendf(msg, "%scannot set MSS to %d", msg->data ? ", " : "", defaultmss);
+			err |= ERR_WARN;
+		}
+	}
+#endif
+#if defined(TCP_USER_TIMEOUT)
+	if (listener->bind_conf->tcp_ut) {
+		if (setsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT,
+			       &listener->bind_conf->tcp_ut, sizeof(listener->bind_conf->tcp_ut)) == -1) {
+			chunk_appendf(msg, "%scannot set TCP User Timeout", msg->data ? ", " : "");
+			err |= ERR_WARN;
+		}
+	} else
+		setsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT, &zero,
+		    sizeof(zero));
+#endif
+#if defined(TCP_DEFER_ACCEPT)
+	if (listener->bind_conf->options & BC_O_DEF_ACCEPT) {
+		/* defer accept by up to one second */
+		int accept_delay = 1;
+		if (setsockopt(fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &accept_delay, sizeof(accept_delay)) == -1) {
+			chunk_appendf(msg, "%scannot enable DEFER_ACCEPT", msg->data ? ", " : "");
+			err |= ERR_WARN;
+		}
+	} else
+		setsockopt(fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &zero,
+		    sizeof(zero));
+#endif
+#if defined(TCP_FASTOPEN)
+	if (listener->bind_conf->options & BC_O_TCP_FO) {
+		/* TFO needs a queue length, let's use the configured backlog */
+		int qlen = listener_backlog(listener);
+		if (setsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN, &qlen, sizeof(qlen)) == -1) {
+			chunk_appendf(msg, "%scannot enable TCP_FASTOPEN", msg->data ? ", " : "");
+			err |= ERR_WARN;
+		}
+	} else {
+		socklen_t len;
+		int qlen;
+		len = sizeof(qlen);
+		/* Only disable fast open if it was enabled, we don't want
+		 * the kernel to create a fast open queue if there's none.
+		 */
+		if (getsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN, &qlen, &len) == 0 &&
+		    qlen != 0) {
+			if (setsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN, &zero,
+			    sizeof(zero)) == -1) {
+				chunk_appendf(msg, "%scannot disable TCP_FASTOPEN", msg->data ? ", " : "");
+				err |= ERR_WARN;
+			}
+		}
+	}
+#endif
+
+	ready = sock_accepting_conn(&listener->rx) > 0;
+
+	if (!ready && /* only listen if not already done by external process */
+	    listen(fd, listener_backlog(listener)) == -1) {
+		err |= ERR_RETRYABLE | ERR_ALERT;
+		chunk_appendf(msg, "%scannot listen to socket", msg->data ? ", " : "");
+		goto tcp_close_return;
+	}
+
+#if !defined(TCP_DEFER_ACCEPT) && defined(SO_ACCEPTFILTER)
+	/* the socket needs to listen first */
+	if (listener->bind_conf->options & BC_O_DEF_ACCEPT) {
+		struct accept_filter_arg accept;
+		memset(&accept, 0, sizeof(accept));
+		strlcpy2(accept.af_name, "dataready", sizeof(accept.af_name));
+		if (setsockopt(fd, SOL_SOCKET, SO_ACCEPTFILTER, &accept, sizeof(accept)) == -1) {
+			chunk_appendf(msg, "%scannot enable ACCEPT_FILTER", msg->data ? ", " : "");
+			err |= ERR_WARN;
+		}
+	}
+#endif
+#if defined(TCP_QUICKACK)
+	if (listener->bind_conf->options & BC_O_NOQUICKACK)
+		setsockopt(fd, IPPROTO_TCP, TCP_QUICKACK, &zero, sizeof(zero));
+	else
+		setsockopt(fd, IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
+#endif
+
+ done:
+	/* the socket is ready */
+	listener_set_state(listener, LI_LISTEN);
+	goto tcp_return;
+
+ tcp_close_return:
+	free_trash_chunk(msg);
+	msg = NULL;
+	close(fd);
+ tcp_return:
+	if (msg && errlen && msg->data) {
+		char pn[INET6_ADDRSTRLEN];
+
+		addr_to_str(&listener->rx.addr, pn, sizeof(pn));
+		snprintf(errmsg, errlen, "%s for [%s:%d]", msg->area, pn, get_host_port(&listener->rx.addr));
+	}
+	free_trash_chunk(msg);
+	msg = NULL;
+	return err;
+}
+
+/* Enable receipt of incoming connections for listener <l>. The receiver must
+ * still be valid.
+ */
+static void tcp_enable_listener(struct listener *l)
+{
+	fd_want_recv_safe(l->rx.fd);
+}
+
+/* Disable receipt of incoming connections for listener <l>. The receiver must
+ * still be valid.
+ */
+static void tcp_disable_listener(struct listener *l)
+{
+	fd_stop_recv(l->rx.fd);
+}
+
+/* Suspend a receiver. Returns < 0 in case of failure, 0 if the receiver
+ * was totally stopped, or > 0 if correctly suspended. Note that inherited FDs
+ * are neither suspended nor resumed, we only enable/disable polling on them.
+ */
+static int tcp_suspend_receiver(struct receiver *rx)
+{
+	const struct sockaddr sa = { .sa_family = AF_UNSPEC };
+	int ret;
+
+	/* We never disconnect a shared FD otherwise we'd break it in the
+	 * parent process and any possible subsequent worker inheriting it.
+	 * Thus we just stop receiving from it.
+	 */
+	if (rx->flags & RX_F_INHERITED)
+		goto done;
+
+	if (connect(rx->fd, &sa, sizeof(sa)) < 0)
+		goto check_already_done;
+ done:
+	fd_stop_recv(rx->fd);
+	return 1;
+
+ check_already_done:
+	/* in case one of the shutdown() above fails, it might be because we're
+	 * dealing with a socket that is shared with other processes doing the
+	 * same. Let's check if it's still accepting connections.
+	 */
+	ret = sock_accepting_conn(rx);
+	if (ret <= 0) {
+		/* unrecoverable or paused by another process */
+		fd_stop_recv(rx->fd);
+		return ret == 0;
+	}
+
+	/* still listening, that's not good */
+	return -1;
+}
+
+/* Resume a receiver. Returns < 0 in case of failure, 0 if the receiver
+ * was totally stopped, or > 0 if correctly resumed. Note that inherited FDs
+ * are neither suspended nor resumed, we only enable/disable polling on them.
+ */
+static int tcp_resume_receiver(struct receiver *rx)
+{
+	struct listener *l = LIST_ELEM(rx, struct listener *, rx);
+
+	if (rx->fd < 0)
+		return 0;
+
+	if ((rx->flags & RX_F_INHERITED) || listen(rx->fd, listener_backlog(l)) == 0) {
+		fd_want_recv(l->rx.fd);
+		return 1;
+	}
+	return -1;
+}
+
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */