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29885f0308
QUIC will rely on UDP at the receiver level, and will need these functions to suspend/resume the receivers. In the future, protocol chaining may simplify this.
230 lines
6.6 KiB
C
230 lines
6.6 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, Frédéric Lécaille <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 <fcntl.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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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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.ctrl_type = SOCK_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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.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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.ctrl_type = SOCK_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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.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 [%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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