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337edfdbc5
The protocol selection is currently performed based on the family, control type and socket type. But this is often not enough, as both only provide DGRAM or STREAM, leaving few variants. Protocols like SCTP for example might be indistinguishable from TCP here. Same goes for TCP extensions like MPTCP. This commit introduces a new enum proto_type that is placed in each and every protocol definition, that will usually more or less match the sock_type, but being an enum, will support additional values.
233 lines
6.7 KiB
C
233 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, 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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#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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.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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.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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.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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.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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