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91b47263f7
There's been some great confusion between proto_type, ctrl_type and
sock_type. It turns out that ctrl_type was improperly chosen because
it's not the control layer that is of this or that type, but the
transport layer, and it turns out that the transport layer doesn't
(normally) denaturate the underlying control layer, except for QUIC
which turns dgrams to streams. The fact that the SOCK_{DGRAM|STREAM}
set of values was used added to the confusion.
Let's replace it with xprt_type which reuses the later introduced
PROTO_TYPE_* values, and update the comments to explain which one
works at what level.
232 lines
6.7 KiB
C
232 lines
6.7 KiB
C
/*
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* UDP protocol layer on top of AF_INET/AF_INET6
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*
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* Copyright 2019 HAProxy Technologies, Frederic Lecaille <flecaille@haproxy.com>
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*
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* Partial merge by Emeric Brun <ebrun@haproxy.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <ctype.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <netinet/udp.h>
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#include <netinet/in.h>
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#include <haproxy/fd.h>
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#include <haproxy/listener.h>
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#include <haproxy/log.h>
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#include <haproxy/namespace.h>
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#include <haproxy/port_range.h>
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#include <haproxy/protocol.h>
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#include <haproxy/proto_udp.h>
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#include <haproxy/proxy.h>
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#include <haproxy/server.h>
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#include <haproxy/sock.h>
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#include <haproxy/sock_inet.h>
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#include <haproxy/task.h>
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#include <haproxy/tools.h>
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static int udp_bind_listener(struct listener *listener, char *errmsg, int errlen);
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static void udp_enable_listener(struct listener *listener);
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static void udp_disable_listener(struct listener *listener);
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/* Note: must not be declared <const> as its list will be overwritten */
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struct protocol proto_udp4 = {
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.name = "udp4",
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/* connection layer */
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.xprt_type = PROTO_TYPE_DGRAM,
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.listen = udp_bind_listener,
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.enable = udp_enable_listener,
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.disable = udp_disable_listener,
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.add = default_add_listener,
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.unbind = default_unbind_listener,
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.suspend = default_suspend_listener,
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.resume = default_resume_listener,
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/* binding layer */
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.rx_suspend = udp_suspend_receiver,
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.rx_resume = udp_resume_receiver,
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/* address family */
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.fam = &proto_fam_inet4,
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/* socket layer */
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.proto_type = PROTO_TYPE_DGRAM,
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.sock_type = SOCK_DGRAM,
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.sock_prot = IPPROTO_UDP,
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.rx_enable = sock_enable,
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.rx_disable = sock_disable,
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.rx_unbind = sock_unbind,
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.receivers = LIST_HEAD_INIT(proto_udp4.receivers),
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.nb_receivers = 0,
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};
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INITCALL1(STG_REGISTER, protocol_register, &proto_udp4);
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/* Note: must not be declared <const> as its list will be overwritten */
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struct protocol proto_udp6 = {
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.name = "udp6",
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/* connection layer */
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.xprt_type = PROTO_TYPE_DGRAM,
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.listen = udp_bind_listener,
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.enable = udp_enable_listener,
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.disable = udp_disable_listener,
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.add = default_add_listener,
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.unbind = default_unbind_listener,
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.suspend = default_suspend_listener,
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.resume = default_resume_listener,
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/* binding layer */
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.rx_suspend = udp_suspend_receiver,
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.rx_resume = udp_resume_receiver,
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/* address family */
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.fam = &proto_fam_inet6,
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/* socket layer */
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.proto_type = PROTO_TYPE_DGRAM,
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.sock_type = SOCK_DGRAM,
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.sock_prot = IPPROTO_UDP,
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.rx_enable = sock_enable,
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.rx_disable = sock_disable,
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.rx_unbind = sock_unbind,
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.receivers = LIST_HEAD_INIT(proto_udp6.receivers),
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.nb_receivers = 0,
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};
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INITCALL1(STG_REGISTER, protocol_register, &proto_udp6);
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/* This function tries to bind a UDPv4/v6 listener. It may return a warning or
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* an error message in <errmsg> if the message is at most <errlen> bytes long
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* (including '\0'). Note that <errmsg> may be NULL if <errlen> is also zero.
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* The return value is composed from ERR_ABORT, ERR_WARN,
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* ERR_ALERT, ERR_RETRYABLE and ERR_FATAL. ERR_NONE indicates that everything
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* was alright and that no message was returned. ERR_RETRYABLE means that an
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* error occurred but that it may vanish after a retry (eg: port in use), and
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* ERR_FATAL indicates a non-fixable error. ERR_WARN and ERR_ALERT do not alter
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* the meaning of the error, but just indicate that a message is present which
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* should be displayed with the respective level. Last, ERR_ABORT indicates
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* that it's pointless to try to start other listeners. No error message is
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* returned if errlen is NULL.
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*/
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int udp_bind_listener(struct listener *listener, char *errmsg, int errlen)
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{
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int err = ERR_NONE;
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char *msg = NULL;
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/* ensure we never return garbage */
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if (errlen)
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*errmsg = 0;
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if (listener->state != LI_ASSIGNED)
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return ERR_NONE; /* already bound */
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if (!(listener->rx.flags & RX_F_BOUND)) {
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msg = "receiving socket not bound";
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goto udp_return;
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}
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listener_set_state(listener, LI_LISTEN);
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udp_return:
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if (msg && errlen) {
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char pn[INET6_ADDRSTRLEN];
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addr_to_str(&listener->rx.addr, pn, sizeof(pn));
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snprintf(errmsg, errlen, "%s for [%s:%d]", msg, pn, get_host_port(&listener->rx.addr));
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}
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return err;
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}
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/* Enable receipt of incoming connections for listener <l>. The receiver must
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* still be valid.
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*/
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static void udp_enable_listener(struct listener *l)
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{
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fd_want_recv_safe(l->rx.fd);
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}
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/* Disable receipt of incoming connections for listener <l>. The receiver must
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* still be valid.
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*/
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static void udp_disable_listener(struct listener *l)
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{
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fd_stop_recv(l->rx.fd);
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}
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/* Suspend a receiver. Returns < 0 in case of failure, 0 if the receiver
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* was totally stopped, or > 0 if correctly suspended.
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* The principle is a bit ugly but works well, at least on Linux: in order to
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* suspend the receiver, we want it to stop receiving traffic, which means that
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* the socket must be unhashed from the kernel's socket table. The simple way
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* to do this is to connect to any address that is reachable and will not be
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* used by regular traffic, and a great one is reconnecting to self.
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*/
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int udp_suspend_receiver(struct receiver *rx)
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{
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struct sockaddr_storage ss;
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socklen_t len = sizeof(ss);
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if (rx->fd < 0)
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return 0;
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/* we never do that with a shared FD otherwise we'd break it in the
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* parent process and any possible subsequent worker inheriting it.
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*/
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if (rx->flags & RX_F_INHERITED)
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return -1;
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if (getsockname(rx->fd, (struct sockaddr *)&ss, &len) < 0)
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return -1;
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if (connect(rx->fd, (struct sockaddr *)&ss, len) < 0)
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return -1;
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/* not necessary but may make debugging clearer */
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fd_stop_recv(rx->fd);
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return 1;
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}
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/* Resume a receiver. Returns < 0 in case of failure, 0 if the receiver
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* was totally stopped, or > 0 if correctly suspended.
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* The principle is to reverse the change above, we'll break the connection by
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* connecting to AF_UNSPEC. The association breaks and the socket starts to
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* receive from everywhere again.
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*/
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int udp_resume_receiver(struct receiver *rx)
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{
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const struct sockaddr sa = { .sa_family = AF_UNSPEC };
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if (rx->fd < 0)
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return 0;
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if (connect(rx->fd, &sa, sizeof(sa)) < 0)
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return -1;
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fd_want_recv(rx->fd);
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return 1;
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}
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/*
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* Local variables:
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* c-indent-level: 8
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* c-basic-offset: 8
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* End:
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*/
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