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/*
* UDP protocol layer on top of AF_INET/AF_INET6
*
* Copyright 2019 HAProxy Technologies, Frederic Lecaille <flecaille@haproxy.com>
*
* Partial merge by Emeric Brun <ebrun@haproxy.com>
*
* 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/udp.h>
#include <netinet/in.h>
#include <haproxy/fd.h>
#include <haproxy/listener.h>
#include <haproxy/log.h>
#include <haproxy/namespace.h>
#include <haproxy/port_range.h>
#include <haproxy/protocol.h>
#include <haproxy/proto_udp.h>
#include <haproxy/proxy.h>
#include <haproxy/server.h>
#include <haproxy/sock.h>
#include <haproxy/sock_inet.h>
#include <haproxy/task.h>
#include <haproxy/tools.h>
static int udp_bind_listener(struct listener *listener, char *errmsg, int errlen);
static void udp_enable_listener(struct listener *listener);
static void udp_disable_listener(struct listener *listener);
/* Note: must not be declared <const> as its list will be overwritten */
struct protocol proto_udp4 = {
.name = "udp4",
/* connection layer */
.xprt_type = PROTO_TYPE_DGRAM,
.listen = udp_bind_listener,
.enable = udp_enable_listener,
.disable = udp_disable_listener,
.add = default_add_listener,
.unbind = default_unbind_listener,
.suspend = default_suspend_listener,
.resume = default_resume_listener,
/* binding layer */
.rx_suspend = udp_suspend_receiver,
.rx_resume = udp_resume_receiver,
/* address family */
.fam = &proto_fam_inet4,
/* socket layer */
.proto_type = PROTO_TYPE_DGRAM,
.sock_type = SOCK_DGRAM,
.sock_prot = IPPROTO_UDP,
.rx_enable = sock_enable,
.rx_disable = sock_disable,
.rx_unbind = sock_unbind,
.receivers = LIST_HEAD_INIT(proto_udp4.receivers),
.nb_receivers = 0,
};
INITCALL1(STG_REGISTER, protocol_register, &proto_udp4);
/* Note: must not be declared <const> as its list will be overwritten */
struct protocol proto_udp6 = {
.name = "udp6",
/* connection layer */
.xprt_type = PROTO_TYPE_DGRAM,
.listen = udp_bind_listener,
.enable = udp_enable_listener,
.disable = udp_disable_listener,
.add = default_add_listener,
.unbind = default_unbind_listener,
.suspend = default_suspend_listener,
.resume = default_resume_listener,
/* binding layer */
.rx_suspend = udp_suspend_receiver,
.rx_resume = udp_resume_receiver,
/* address family */
.fam = &proto_fam_inet6,
/* socket layer */
.proto_type = PROTO_TYPE_DGRAM,
.sock_type = SOCK_DGRAM,
.sock_prot = IPPROTO_UDP,
.rx_enable = sock_enable,
.rx_disable = sock_disable,
.rx_unbind = sock_unbind,
.receivers = LIST_HEAD_INIT(proto_udp6.receivers),
.nb_receivers = 0,
};
INITCALL1(STG_REGISTER, protocol_register, &proto_udp6);
/* This function tries to bind a UDPv4/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 udp_bind_listener(struct listener *listener, char *errmsg, int errlen)
{
int err = ERR_NONE;
char *msg = NULL;
/* 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)) {
msg = "receiving socket not bound";
goto udp_return;
}
listener_set_state(listener, LI_LISTEN);
udp_return:
if (msg && errlen) {
char pn[INET6_ADDRSTRLEN];
addr_to_str(&listener->rx.addr, pn, sizeof(pn));
snprintf(errmsg, errlen, "%s for [%s:%d]", msg, pn, get_host_port(&listener->rx.addr));
}
return err;
}
/* Enable receipt of incoming connections for listener <l>. The receiver must
* still be valid.
*/
static void udp_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 udp_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.
* The principle is a bit ugly but works well, at least on Linux: in order to
* suspend the receiver, we want it to stop receiving traffic, which means that
* the socket must be unhashed from the kernel's socket table. The simple way
* to do this is to connect to any address that is reachable and will not be
* used by regular traffic, and a great one is reconnecting to self. Note that
* inherited FDs are neither suspended nor resumed, we only enable/disable
* polling on them.
*/
int udp_suspend_receiver(struct receiver *rx)
{
struct sockaddr_storage ss;
socklen_t len = sizeof(ss);
if (rx->fd < 0)
return 0;
/* we never do that with a shared FD otherwise we'd break it in the
* parent process and any possible subsequent worker inheriting it.
*/
if (rx->flags & RX_F_INHERITED)
goto done;
if (getsockname(rx->fd, (struct sockaddr *)&ss, &len) < 0)
return -1;
if (connect(rx->fd, (struct sockaddr *)&ss, len) < 0)
return -1;
done:
/* not necessary but may make debugging clearer */
fd_stop_recv(rx->fd);
return 1;
}
/* Resume a receiver. Returns < 0 in case of failure, 0 if the receiver
* was totally stopped, or > 0 if correctly suspended.
* The principle is to reverse the change above, we'll break the connection by
* connecting to AF_UNSPEC. The association breaks and the socket starts to
* receive from everywhere again. Note that inherited FDs are neither suspended
* nor resumed, we only enable/disable polling on them.
*/
int udp_resume_receiver(struct receiver *rx)
{
const struct sockaddr sa = { .sa_family = AF_UNSPEC };
if (rx->fd < 0)
return 0;
if (!(rx->flags & RX_F_INHERITED) && connect(rx->fd, &sa, sizeof(sa)) < 0)
return -1;
fd_want_recv(rx->fd);
return 1;
}
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/
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