io: introduce a DNS resolver API
Currently DNS resolution is done automatically as part of the creation of a QIOChannelSocket object instance. This works ok for network clients where you just end up a single network socket, but for servers, the results of DNS resolution may require creation of multiple sockets. Introducing a DNS resolver API allows DNS resolution to be separated from the socket object creation. This will make it practical to create multiple QIOChannelSocket instances for servers. Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange
parent
59de517d8d
commit
c1b412f1d9
228
include/io/dns-resolver.h
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228
include/io/dns-resolver.h
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@ -0,0 +1,228 @@
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/*
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* QEMU DNS resolver
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*
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* Copyright (c) 2016-2017 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef QIO_DNS_RESOLVER_H
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#define QIO_DNS_RESOLVER_H
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#include "qemu-common.h"
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#include "qom/object.h"
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#include "io/task.h"
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#define TYPE_QIO_DNS_RESOLVER "qio-dns-resolver"
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#define QIO_DNS_RESOLVER(obj) \
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OBJECT_CHECK(QIODNSResolver, (obj), TYPE_QIO_DNS_RESOLVER)
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#define QIO_DNS_RESOLVER_CLASS(klass) \
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OBJECT_CLASS_CHECK(QIODNSResolverClass, klass, TYPE_QIO_DNS_RESOLVER)
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#define QIO_DNS_RESOLVER_GET_CLASS(obj) \
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OBJECT_GET_CLASS(QIODNSResolverClass, obj, TYPE_QIO_DNS_RESOLVER)
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typedef struct QIODNSResolver QIODNSResolver;
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typedef struct QIODNSResolverClass QIODNSResolverClass;
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/**
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* QIODNSResolver:
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*
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* The QIODNSResolver class provides a framework for doing
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* DNS resolution on SocketAddress objects, independently
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* of socket creation.
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*
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* <example>
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* <title>Resolving addresses synchronously</title>
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* <programlisting>
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* int mylisten(SocketAddress *addr, Error **errp) {
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* QIODNSResolver *resolver = qio_dns_resolver_get_instance();
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* SocketAddress **rawaddrs = NULL;
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* size_t nrawaddrs = 0;
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* Error *err = NULL;
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* QIOChannel **socks = NULL;
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* size_t nsocks = 0;
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*
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* if (qio_dns_resolver_lookup_sync(dns, addr, &nrawaddrs,
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* &rawaddrs, errp) < 0) {
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* return -1;
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* }
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*
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* for (i = 0; i < nrawaddrs; i++) {
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* QIOChannel *sock = qio_channel_new();
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* Error *local_err = NULL;
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* qio_channel_listen_sync(sock, rawaddrs[i], &local_err);
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* if (local_err) {
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* error_propagate(&err, local_err);
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* } else {
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* socks = g_renew(QIOChannelSocket *, socks, nsocks + 1);
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* socks[nsocks++] = sock;
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* }
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* qapi_free_SocketAddress(rawaddrs[i]);
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* }
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* g_free(rawaddrs);
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*
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* if (nsocks == 0) {
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* error_propagate(errp, err);
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* } else {
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* error_free(err);
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* }
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* }
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* </programlisting>
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* </example>
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*
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* <example>
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* <title>Resolving addresses asynchronously</title>
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* <programlisting>
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* typedef struct MyListenData {
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* Error *err;
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* QIOChannelSocket **socks;
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* size_t nsocks;
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* } MyListenData;
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*
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* void mylistenresult(QIOTask *task, void *opaque) {
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* MyListenData *data = opaque;
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* QIODNSResolver *resolver =
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* QIO_DNS_RESOLVER(qio_task_get_source(task);
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* SocketAddress **rawaddrs = NULL;
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* size_t nrawaddrs = 0;
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* Error *err = NULL;
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*
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* if (qio_task_propagate_error(task, &data->err)) {
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* return;
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* }
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*
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* qio_dns_resolver_lookup_result(resolver, task,
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* &nrawaddrs, &rawaddrs);
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*
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* for (i = 0; i < nrawaddrs; i++) {
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* QIOChannel *sock = qio_channel_new();
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* Error *local_err = NULL;
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* qio_channel_listen_sync(sock, rawaddrs[i], &local_err);
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* if (local_err) {
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* error_propagate(&err, local_err);
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* } else {
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* socks = g_renew(QIOChannelSocket *, socks, nsocks + 1);
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* socks[nsocks++] = sock;
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* }
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* qapi_free_SocketAddress(rawaddrs[i]);
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* }
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* g_free(rawaddrs);
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*
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* if (nsocks == 0) {
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* error_propagate(&data->err, err);
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* } else {
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* error_free(err);
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* }
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* }
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*
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* void mylisten(SocketAddress *addr, MyListenData *data) {
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* QIODNSResolver *resolver = qio_dns_resolver_get_instance();
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* qio_dns_resolver_lookup_async(dns, addr,
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* mylistenresult, data, NULL);
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* }
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* </programlisting>
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* </example>
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*/
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struct QIODNSResolver {
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Object parent;
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};
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struct QIODNSResolverClass {
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ObjectClass parent;
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};
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/**
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* qio_dns_resolver_get_instance:
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*
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* Get the singleton dns resolver instance. The caller
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* does not own a reference on the returned object.
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*
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* Returns: the single dns resolver instance
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*/
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QIODNSResolver *qio_dns_resolver_get_instance(void);
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/**
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* qio_dns_resolver_lookup_sync:
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* @resolver: the DNS resolver instance
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* @addr: the address to resolve
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* @naddr: pointer to hold number of resolved addresses
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* @addrs: pointer to hold resolved addresses
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* @errp: pointer to NULL initialized error object
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*
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* This will attempt to resolve the address provided
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* in @addr. If resolution succeeds, @addrs will be filled
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* with all the resolved addresses. @naddrs will specify
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* the number of entries allocated in @addrs. The caller
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* is responsible for freeing each entry in @addrs, as
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* well as @addrs itself. @naddrs is guaranteed to be
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* greater than zero on success.
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*
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* DNS resolution will be done synchronously so execution
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* of the caller may be blocked for an arbitrary length
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* of time.
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*
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* Returns: 0 if resolution was successful, -1 on error
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*/
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int qio_dns_resolver_lookup_sync(QIODNSResolver *resolver,
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SocketAddress *addr,
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size_t *naddrs,
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SocketAddress ***addrs,
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Error **errp);
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/**
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* qio_dns_resolver_lookup_async:
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* @resolver: the DNS resolver instance
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* @addr: the address to resolve
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* @func: the callback to invoke on lookup completion
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* @opaque: data blob to pass to @func
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* @notify: the callback to free @opaque, or NULL
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*
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* This will attempt to resolve the address provided
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* in @addr. The callback @func will be invoked when
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* resolution has either completed or failed. On
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* success, the @func should call the method
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* qio_dns_resolver_lookup_result() to obtain the
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* results.
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*
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* DNS resolution will be done asynchronously so execution
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* of the caller will not be blocked.
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*/
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void qio_dns_resolver_lookup_async(QIODNSResolver *resolver,
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SocketAddress *addr,
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QIOTaskFunc func,
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gpointer opaque,
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GDestroyNotify notify);
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/**
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* qio_dns_resolver_lookup_result:
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* @resolver: the DNS resolver instance
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* @task: the task object to get results for
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* @naddr: pointer to hold number of resolved addresses
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* @addrs: pointer to hold resolved addresses
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*
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* This method should be called from the callback passed
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* to qio_dns_resolver_lookup_async() in order to obtain
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* results. @addrs will be filled with all the resolved
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* addresses. @naddrs will specify the number of entries
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* allocated in @addrs. The caller is responsible for
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* freeing each entry in @addrs, as well as @addrs itself.
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*/
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void qio_dns_resolver_lookup_result(QIODNSResolver *resolver,
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QIOTask *task,
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size_t *naddrs,
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SocketAddress ***addrs);
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#endif /* QIO_DNS_RESOLVER_H */
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@ -32,6 +32,8 @@ int socket_set_fast_reuse(int fd);
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*/
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typedef void NonBlockingConnectHandler(int fd, Error *err, void *opaque);
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int inet_ai_family_from_address(InetSocketAddress *addr,
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Error **errp);
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InetSocketAddress *inet_parse(const char *str, Error **errp);
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int inet_connect(const char *str, Error **errp);
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int inet_connect_saddr(InetSocketAddress *saddr, Error **errp,
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@ -7,4 +7,5 @@ io-obj-y += channel-tls.o
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io-obj-y += channel-watch.o
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io-obj-y += channel-websock.o
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io-obj-y += channel-util.o
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io-obj-y += dns-resolver.o
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io-obj-y += task.o
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276
io/dns-resolver.c
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276
io/dns-resolver.c
Normal file
@ -0,0 +1,276 @@
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/*
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* QEMU DNS resolver
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*
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* Copyright (c) 2016 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "io/dns-resolver.h"
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#include "qapi/clone-visitor.h"
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#include "qemu/sockets.h"
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#include "qapi/error.h"
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#include "qemu/cutils.h"
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#ifndef AI_NUMERICSERV
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# define AI_NUMERICSERV 0
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#endif
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static QIODNSResolver *instance;
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static GOnce instance_init = G_ONCE_INIT;
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static gpointer qio_dns_resolve_init_instance(gpointer unused G_GNUC_UNUSED)
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{
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instance = QIO_DNS_RESOLVER(object_new(TYPE_QIO_DNS_RESOLVER));
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return NULL;
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}
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QIODNSResolver *qio_dns_resolver_get_instance(void)
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{
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g_once(&instance_init, qio_dns_resolve_init_instance, NULL);
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return instance;
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}
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static int qio_dns_resolver_lookup_sync_inet(QIODNSResolver *resolver,
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SocketAddress *addr,
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size_t *naddrs,
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SocketAddress ***addrs,
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Error **errp)
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{
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struct addrinfo ai, *res, *e;
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InetSocketAddress *iaddr = addr->u.inet.data;
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char port[33];
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char uaddr[INET6_ADDRSTRLEN + 1];
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char uport[33];
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int rc;
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Error *err = NULL;
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size_t i;
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*naddrs = 0;
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*addrs = NULL;
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memset(&ai, 0, sizeof(ai));
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ai.ai_flags = AI_PASSIVE;
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if (iaddr->has_numeric && iaddr->numeric) {
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ai.ai_flags |= AI_NUMERICHOST | AI_NUMERICSERV;
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}
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ai.ai_family = inet_ai_family_from_address(iaddr, &err);
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ai.ai_socktype = SOCK_STREAM;
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if (err) {
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error_propagate(errp, err);
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return -1;
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}
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if (iaddr->host == NULL) {
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error_setg(errp, "host not specified");
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return -1;
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}
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if (iaddr->port != NULL) {
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pstrcpy(port, sizeof(port), iaddr->port);
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} else {
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port[0] = '\0';
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}
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rc = getaddrinfo(strlen(iaddr->host) ? iaddr->host : NULL,
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strlen(port) ? port : NULL, &ai, &res);
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if (rc != 0) {
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error_setg(errp, "address resolution failed for %s:%s: %s",
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iaddr->host, port, gai_strerror(rc));
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return -1;
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}
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for (e = res; e != NULL; e = e->ai_next) {
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(*naddrs)++;
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}
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*addrs = g_new0(SocketAddress *, *naddrs);
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/* create socket + bind */
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for (i = 0, e = res; e != NULL; i++, e = e->ai_next) {
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SocketAddress *newaddr = g_new0(SocketAddress, 1);
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InetSocketAddress *newiaddr = g_new0(InetSocketAddress, 1);
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newaddr->u.inet.data = newiaddr;
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newaddr->type = SOCKET_ADDRESS_KIND_INET;
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getnameinfo((struct sockaddr *)e->ai_addr, e->ai_addrlen,
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uaddr, INET6_ADDRSTRLEN, uport, 32,
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NI_NUMERICHOST | NI_NUMERICSERV);
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*newiaddr = (InetSocketAddress){
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.host = g_strdup(uaddr),
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.port = g_strdup(uport),
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.has_numeric = true,
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.numeric = true,
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.has_to = iaddr->has_to,
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.to = iaddr->to,
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.has_ipv4 = false,
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.has_ipv6 = false,
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};
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(*addrs)[i] = newaddr;
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}
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freeaddrinfo(res);
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return 0;
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}
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static int qio_dns_resolver_lookup_sync_nop(QIODNSResolver *resolver,
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SocketAddress *addr,
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size_t *naddrs,
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SocketAddress ***addrs,
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Error **errp)
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{
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*naddrs = 1;
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*addrs = g_new0(SocketAddress *, 1);
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(*addrs)[0] = QAPI_CLONE(SocketAddress, addr);
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return 0;
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}
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int qio_dns_resolver_lookup_sync(QIODNSResolver *resolver,
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SocketAddress *addr,
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size_t *naddrs,
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SocketAddress ***addrs,
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Error **errp)
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{
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switch (addr->type) {
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case SOCKET_ADDRESS_KIND_INET:
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return qio_dns_resolver_lookup_sync_inet(resolver,
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addr,
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naddrs,
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addrs,
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errp);
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case SOCKET_ADDRESS_KIND_UNIX:
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case SOCKET_ADDRESS_KIND_VSOCK:
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return qio_dns_resolver_lookup_sync_nop(resolver,
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addr,
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naddrs,
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addrs,
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errp);
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default:
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error_setg(errp, "Unknown socket address kind");
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return -1;
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}
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}
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struct QIODNSResolverLookupData {
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SocketAddress *addr;
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SocketAddress **addrs;
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size_t naddrs;
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};
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static void qio_dns_resolver_lookup_data_free(gpointer opaque)
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{
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struct QIODNSResolverLookupData *data = opaque;
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size_t i;
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qapi_free_SocketAddress(data->addr);
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for (i = 0; i < data->naddrs; i++) {
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qapi_free_SocketAddress(data->addrs[i]);
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}
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g_free(data->addrs);
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g_free(data);
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}
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static void qio_dns_resolver_lookup_worker(QIOTask *task,
|
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gpointer opaque)
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{
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QIODNSResolver *resolver = QIO_DNS_RESOLVER(qio_task_get_source(task));
|
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struct QIODNSResolverLookupData *data = opaque;
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Error *err = NULL;
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qio_dns_resolver_lookup_sync(resolver,
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data->addr,
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&data->naddrs,
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&data->addrs,
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&err);
|
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if (err) {
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qio_task_set_error(task, err);
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} else {
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qio_task_set_result_pointer(task, opaque, NULL);
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}
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object_unref(OBJECT(resolver));
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}
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void qio_dns_resolver_lookup_async(QIODNSResolver *resolver,
|
||||
SocketAddress *addr,
|
||||
QIOTaskFunc func,
|
||||
gpointer opaque,
|
||||
GDestroyNotify notify)
|
||||
{
|
||||
QIOTask *task;
|
||||
struct QIODNSResolverLookupData *data =
|
||||
g_new0(struct QIODNSResolverLookupData, 1);
|
||||
|
||||
data->addr = QAPI_CLONE(SocketAddress, addr);
|
||||
|
||||
task = qio_task_new(OBJECT(resolver), func, opaque, notify);
|
||||
|
||||
qio_task_run_in_thread(task,
|
||||
qio_dns_resolver_lookup_worker,
|
||||
data,
|
||||
qio_dns_resolver_lookup_data_free);
|
||||
}
|
||||
|
||||
|
||||
void qio_dns_resolver_lookup_result(QIODNSResolver *resolver,
|
||||
QIOTask *task,
|
||||
size_t *naddrs,
|
||||
SocketAddress ***addrs)
|
||||
{
|
||||
struct QIODNSResolverLookupData *data =
|
||||
qio_task_get_result_pointer(task);
|
||||
size_t i;
|
||||
|
||||
*naddrs = 0;
|
||||
*addrs = NULL;
|
||||
if (!data) {
|
||||
return;
|
||||
}
|
||||
|
||||
*naddrs = data->naddrs;
|
||||
*addrs = g_new0(SocketAddress *, data->naddrs);
|
||||
for (i = 0; i < data->naddrs; i++) {
|
||||
(*addrs)[i] = QAPI_CLONE(SocketAddress, data->addrs[i]);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
static const TypeInfo qio_dns_resolver_info = {
|
||||
.parent = TYPE_OBJECT,
|
||||
.name = TYPE_QIO_DNS_RESOLVER,
|
||||
.instance_size = sizeof(QIODNSResolver),
|
||||
.class_size = sizeof(QIODNSResolverClass),
|
||||
};
|
||||
|
||||
|
||||
static void qio_dns_resolver_register_types(void)
|
||||
{
|
||||
type_register_static(&qio_dns_resolver_info);
|
||||
}
|
||||
|
||||
|
||||
type_init(qio_dns_resolver_register_types);
|
||||
@ -114,7 +114,7 @@ NetworkAddressFamily inet_netfamily(int family)
|
||||
* outside scope of this method and not currently handled by
|
||||
* callers at all.
|
||||
*/
|
||||
static int inet_ai_family_from_address(InetSocketAddress *addr,
|
||||
int inet_ai_family_from_address(InetSocketAddress *addr,
|
||||
Error **errp)
|
||||
{
|
||||
if (addr->has_ipv6 && addr->has_ipv4 &&
|
||||
|
||||
Loading…
Reference in New Issue
Block a user