io: add QIOChannelSocket class

Implement a QIOChannel subclass that supports sockets I/O.
The implementation is able to manage a single socket file
descriptor, whether a TCP/UNIX listener, TCP/UNIX connection,
or a UDP datagram. It provides APIs which can listen and
connect either asynchronously or synchronously. Since there
is no asynchronous DNS lookup API available, it uses the
QIOTask helper for spawning a background thread to ensure
non-blocking operation.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

io/Makefile.objs

@@ -1,3 +1,4 @@
 io-obj-y = channel.o
+io-obj-y += channel-socket.o
 io-obj-y += channel-watch.o
 io-obj-y += task.o

io/channel-socket.c

@@ -0,0 +1,741 @@
+/*
+ * QEMU I/O channels sockets driver
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "io/channel-socket.h"
+#include "io/channel-watch.h"
+#include "trace.h"
+
+#define SOCKET_MAX_FDS 16
+
+SocketAddress *
+qio_channel_socket_get_local_address(QIOChannelSocket *ioc,
+                                     Error **errp)
+{
+    return socket_sockaddr_to_address(&ioc->localAddr,
+                                      ioc->localAddrLen,
+                                      errp);
+}
+
+SocketAddress *
+qio_channel_socket_get_remote_address(QIOChannelSocket *ioc,
+                                      Error **errp)
+{
+    return socket_sockaddr_to_address(&ioc->remoteAddr,
+                                      ioc->remoteAddrLen,
+                                      errp);
+}
+
+QIOChannelSocket *
+qio_channel_socket_new(void)
+{
+    QIOChannelSocket *sioc;
+    QIOChannel *ioc;
+
+    sioc = QIO_CHANNEL_SOCKET(object_new(TYPE_QIO_CHANNEL_SOCKET));
+    sioc->fd = -1;
+
+    ioc = QIO_CHANNEL(sioc);
+    ioc->features |= (1 << QIO_CHANNEL_FEATURE_SHUTDOWN);
+
+    trace_qio_channel_socket_new(sioc);
+
+    return sioc;
+}
+
+
+static int
+qio_channel_socket_set_fd(QIOChannelSocket *sioc,
+                          int fd,
+                          Error **errp)
+{
+    if (sioc->fd != -1) {
+        error_setg(errp, "Socket is already open");
+        return -1;
+    }
+
+    sioc->fd = fd;
+    sioc->remoteAddrLen = sizeof(sioc->remoteAddr);
+    sioc->localAddrLen = sizeof(sioc->localAddr);
+
+
+    if (getpeername(fd, (struct sockaddr *)&sioc->remoteAddr,
+                    &sioc->remoteAddrLen) < 0) {
+        if (socket_error() == ENOTCONN) {
+            memset(&sioc->remoteAddr, 0, sizeof(sioc->remoteAddr));
+            sioc->remoteAddrLen = sizeof(sioc->remoteAddr);
+        } else {
+            error_setg_errno(errp, socket_error(),
+                             "Unable to query remote socket address");
+            goto error;
+        }
+    }
+
+    if (getsockname(fd, (struct sockaddr *)&sioc->localAddr,
+                    &sioc->localAddrLen) < 0) {
+        error_setg_errno(errp, socket_error(),
+                         "Unable to query local socket address");
+        goto error;
+    }
+
+#ifndef WIN32
+    if (sioc->localAddr.ss_family == AF_UNIX) {
+        QIOChannel *ioc = QIO_CHANNEL(sioc);
+        ioc->features |= (1 << QIO_CHANNEL_FEATURE_FD_PASS);
+    }
+#endif /* WIN32 */
+
+    return 0;
+
+ error:
+    sioc->fd = -1; /* Let the caller close FD on failure */
+    return -1;
+}
+
+QIOChannelSocket *
+qio_channel_socket_new_fd(int fd,
+                          Error **errp)
+{
+    QIOChannelSocket *ioc;
+
+    ioc = qio_channel_socket_new();
+    if (qio_channel_socket_set_fd(ioc, fd, errp) < 0) {
+        object_unref(OBJECT(ioc));
+        return NULL;
+    }
+
+    trace_qio_channel_socket_new_fd(ioc, fd);
+
+    return ioc;
+}
+
+
+int qio_channel_socket_connect_sync(QIOChannelSocket *ioc,
+                                    SocketAddress *addr,
+                                    Error **errp)
+{
+    int fd;
+
+    trace_qio_channel_socket_connect_sync(ioc, addr);
+    fd = socket_connect(addr, errp, NULL, NULL);
+    if (fd < 0) {
+        trace_qio_channel_socket_connect_fail(ioc);
+        return -1;
+    }
+
+    trace_qio_channel_socket_connect_complete(ioc, fd);
+    if (qio_channel_socket_set_fd(ioc, fd, errp) < 0) {
+        close(fd);
+        return -1;
+    }
+
+    return 0;
+}
+
+
+static int qio_channel_socket_connect_worker(QIOTask *task,
+                                             Error **errp,
+                                             gpointer opaque)
+{
+    QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
+    SocketAddress *addr = opaque;
+    int ret;
+
+    ret = qio_channel_socket_connect_sync(ioc,
+                                          addr,
+                                          errp);
+
+    object_unref(OBJECT(ioc));
+    return ret;
+}
+
+
+void qio_channel_socket_connect_async(QIOChannelSocket *ioc,
+                                      SocketAddress *addr,
+                                      QIOTaskFunc callback,
+                                      gpointer opaque,
+                                      GDestroyNotify destroy)
+{
+    QIOTask *task = qio_task_new(
+        OBJECT(ioc), callback, opaque, destroy);
+    SocketAddress *addrCopy;
+
+    qapi_copy_SocketAddress(&addrCopy, addr);
+
+    /* socket_connect() does a non-blocking connect(), but it
+     * still blocks in DNS lookups, so we must use a thread */
+    trace_qio_channel_socket_connect_async(ioc, addr);
+    qio_task_run_in_thread(task,
+                           qio_channel_socket_connect_worker,
+                           addrCopy,
+                           (GDestroyNotify)qapi_free_SocketAddress);
+}
+
+
+int qio_channel_socket_listen_sync(QIOChannelSocket *ioc,
+                                   SocketAddress *addr,
+                                   Error **errp)
+{
+    int fd;
+
+    trace_qio_channel_socket_listen_sync(ioc, addr);
+    fd = socket_listen(addr, errp);
+    if (fd < 0) {
+        trace_qio_channel_socket_listen_fail(ioc);
+        return -1;
+    }
+
+    trace_qio_channel_socket_listen_complete(ioc, fd);
+    if (qio_channel_socket_set_fd(ioc, fd, errp) < 0) {
+        close(fd);
+        return -1;
+    }
+
+    return 0;
+}
+
+
+static int qio_channel_socket_listen_worker(QIOTask *task,
+                                            Error **errp,
+                                            gpointer opaque)
+{
+    QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
+    SocketAddress *addr = opaque;
+    int ret;
+
+    ret = qio_channel_socket_listen_sync(ioc,
+                                         addr,
+                                         errp);
+
+    object_unref(OBJECT(ioc));
+    return ret;
+}
+
+
+void qio_channel_socket_listen_async(QIOChannelSocket *ioc,
+                                     SocketAddress *addr,
+                                     QIOTaskFunc callback,
+                                     gpointer opaque,
+                                     GDestroyNotify destroy)
+{
+    QIOTask *task = qio_task_new(
+        OBJECT(ioc), callback, opaque, destroy);
+    SocketAddress *addrCopy;
+
+    qapi_copy_SocketAddress(&addrCopy, addr);
+
+    /* socket_listen() blocks in DNS lookups, so we must use a thread */
+    trace_qio_channel_socket_listen_async(ioc, addr);
+    qio_task_run_in_thread(task,
+                           qio_channel_socket_listen_worker,
+                           addrCopy,
+                           (GDestroyNotify)qapi_free_SocketAddress);
+}
+
+
+int qio_channel_socket_dgram_sync(QIOChannelSocket *ioc,
+                                  SocketAddress *localAddr,
+                                  SocketAddress *remoteAddr,
+                                  Error **errp)
+{
+    int fd;
+
+    trace_qio_channel_socket_dgram_sync(ioc, localAddr, remoteAddr);
+    fd = socket_dgram(localAddr, remoteAddr, errp);
+    if (fd < 0) {
+        trace_qio_channel_socket_dgram_fail(ioc);
+        return -1;
+    }
+
+    trace_qio_channel_socket_dgram_complete(ioc, fd);
+    if (qio_channel_socket_set_fd(ioc, fd, errp) < 0) {
+        close(fd);
+        return -1;
+    }
+
+    return 0;
+}
+
+
+struct QIOChannelSocketDGramWorkerData {
+    SocketAddress *localAddr;
+    SocketAddress *remoteAddr;
+};
+
+
+static void qio_channel_socket_dgram_worker_free(gpointer opaque)
+{
+    struct QIOChannelSocketDGramWorkerData *data = opaque;
+    qapi_free_SocketAddress(data->localAddr);
+    qapi_free_SocketAddress(data->remoteAddr);
+    g_free(data);
+}
+
+static int qio_channel_socket_dgram_worker(QIOTask *task,
+                                           Error **errp,
+                                           gpointer opaque)
+{
+    QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
+    struct QIOChannelSocketDGramWorkerData *data = opaque;
+    int ret;
+
+    /* socket_dgram() blocks in DNS lookups, so we must use a thread */
+    ret = qio_channel_socket_dgram_sync(ioc,
+                                        data->localAddr,
+                                        data->remoteAddr,
+                                        errp);
+
+    object_unref(OBJECT(ioc));
+    return ret;
+}
+
+
+void qio_channel_socket_dgram_async(QIOChannelSocket *ioc,
+                                    SocketAddress *localAddr,
+                                    SocketAddress *remoteAddr,
+                                    QIOTaskFunc callback,
+                                    gpointer opaque,
+                                    GDestroyNotify destroy)
+{
+    QIOTask *task = qio_task_new(
+        OBJECT(ioc), callback, opaque, destroy);
+    struct QIOChannelSocketDGramWorkerData *data = g_new0(
+        struct QIOChannelSocketDGramWorkerData, 1);
+
+    qapi_copy_SocketAddress(&data->localAddr, localAddr);
+    qapi_copy_SocketAddress(&data->remoteAddr, remoteAddr);
+
+    trace_qio_channel_socket_dgram_async(ioc, localAddr, remoteAddr);
+    qio_task_run_in_thread(task,
+                           qio_channel_socket_dgram_worker,
+                           data,
+                           qio_channel_socket_dgram_worker_free);
+}
+
+
+QIOChannelSocket *
+qio_channel_socket_accept(QIOChannelSocket *ioc,
+                          Error **errp)
+{
+    QIOChannelSocket *cioc;
+
+    cioc = QIO_CHANNEL_SOCKET(object_new(TYPE_QIO_CHANNEL_SOCKET));
+    cioc->fd = -1;
+    cioc->remoteAddrLen = sizeof(ioc->remoteAddr);
+    cioc->localAddrLen = sizeof(ioc->localAddr);
+
+ retry:
+    trace_qio_channel_socket_accept(ioc);
+    cioc->fd = accept(ioc->fd, (struct sockaddr *)&cioc->remoteAddr,
+                      &cioc->remoteAddrLen);
+    if (cioc->fd < 0) {
+        trace_qio_channel_socket_accept_fail(ioc);
+        if (socket_error() == EINTR) {
+            goto retry;
+        }
+        goto error;
+    }
+
+    if (getsockname(cioc->fd, (struct sockaddr *)&ioc->localAddr,
+                    &ioc->localAddrLen) < 0) {
+        error_setg_errno(errp, socket_error(),
+                         "Unable to query local socket address");
+        goto error;
+    }
+
+    trace_qio_channel_socket_accept_complete(ioc, cioc, cioc->fd);
+    return cioc;
+
+ error:
+    object_unref(OBJECT(cioc));
+    return NULL;
+}
+
+static void qio_channel_socket_init(Object *obj)
+{
+    QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(obj);
+    ioc->fd = -1;
+}
+
+static void qio_channel_socket_finalize(Object *obj)
+{
+    QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(obj);
+    if (ioc->fd != -1) {
+        close(ioc->fd);
+        ioc->fd = -1;
+    }
+}
+
+
+#ifndef WIN32
+static void qio_channel_socket_copy_fds(struct msghdr *msg,
+                                        int **fds, size_t *nfds)
+{
+    struct cmsghdr *cmsg;
+
+    *nfds = 0;
+    *fds = NULL;
+
+    for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+        int fd_size, i;
+        int gotfds;
+
+        if (cmsg->cmsg_len < CMSG_LEN(sizeof(int)) ||
+            cmsg->cmsg_level != SOL_SOCKET ||
+            cmsg->cmsg_type != SCM_RIGHTS) {
+            continue;
+        }
+
+        fd_size = cmsg->cmsg_len - CMSG_LEN(0);
+
+        if (!fd_size) {
+            continue;
+        }
+
+        gotfds = fd_size / sizeof(int);
+        *fds = g_renew(int, *fds, *nfds + gotfds);
+        memcpy(*fds + *nfds, CMSG_DATA(cmsg), fd_size);
+
+        for (i = 0; i < gotfds; i++) {
+            int fd = (*fds)[*nfds + i];
+            if (fd < 0) {
+                continue;
+            }
+
+            /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */
+            qemu_set_block(fd);
+
+#ifndef MSG_CMSG_CLOEXEC
+            qemu_set_cloexec(fd);
+#endif
+        }
+        *nfds += gotfds;
+    }
+}
+
+
+static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
+                                        const struct iovec *iov,
+                                        size_t niov,
+                                        int **fds,
+                                        size_t *nfds,
+                                        Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    ssize_t ret;
+    struct msghdr msg = { NULL, };
+    char control[CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS)];
+    int sflags = 0;
+
+#ifdef MSG_CMSG_CLOEXEC
+    sflags |= MSG_CMSG_CLOEXEC;
+#endif
+
+    msg.msg_iov = (struct iovec *)iov;
+    msg.msg_iovlen = niov;
+    if (fds && nfds) {
+        msg.msg_control = control;
+        msg.msg_controllen = sizeof(control);
+    }
+
+ retry:
+    ret = recvmsg(sioc->fd, &msg, sflags);
+    if (ret < 0) {
+        if (socket_error() == EAGAIN ||
+            socket_error() == EWOULDBLOCK) {
+            return QIO_CHANNEL_ERR_BLOCK;
+        }
+        if (socket_error() == EINTR) {
+            goto retry;
+        }
+
+        error_setg_errno(errp, socket_error(),
+                         "Unable to read from socket");
+        return -1;
+    }
+
+    if (fds && nfds) {
+        qio_channel_socket_copy_fds(&msg, fds, nfds);
+    }
+
+    return ret;
+}
+
+static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
+                                         const struct iovec *iov,
+                                         size_t niov,
+                                         int *fds,
+                                         size_t nfds,
+                                         Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    ssize_t ret;
+    struct msghdr msg = { NULL, };
+
+    msg.msg_iov = (struct iovec *)iov;
+    msg.msg_iovlen = niov;
+
+    if (nfds) {
+        char control[CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS)];
+        size_t fdsize = sizeof(int) * nfds;
+        struct cmsghdr *cmsg;
+
+        if (nfds > SOCKET_MAX_FDS) {
+            error_setg_errno(errp, -EINVAL,
+                             "Only %d FDs can be sent, got %zu",
+                             SOCKET_MAX_FDS, nfds);
+            return -1;
+        }
+
+        msg.msg_control = control;
+        msg.msg_controllen = CMSG_SPACE(sizeof(int) * nfds);
+
+        cmsg = CMSG_FIRSTHDR(&msg);
+        cmsg->cmsg_len = CMSG_LEN(fdsize);
+        cmsg->cmsg_level = SOL_SOCKET;
+        cmsg->cmsg_type = SCM_RIGHTS;
+        memcpy(CMSG_DATA(cmsg), fds, fdsize);
+    }
+
+ retry:
+    ret = sendmsg(sioc->fd, &msg, 0);
+    if (ret <= 0) {
+        if (socket_error() == EAGAIN ||
+            socket_error() == EWOULDBLOCK) {
+            return QIO_CHANNEL_ERR_BLOCK;
+        }
+        if (socket_error() == EINTR) {
+            goto retry;
+        }
+        error_setg_errno(errp, socket_error(),
+                         "Unable to write to socket");
+        return -1;
+    }
+    return ret;
+}
+#else /* WIN32 */
+static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
+                                        const struct iovec *iov,
+                                        size_t niov,
+                                        int **fds,
+                                        size_t *nfds,
+                                        Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    ssize_t done = 0;
+    ssize_t i;
+
+    for (i = 0; i < niov; i++) {
+        ssize_t ret;
+    retry:
+        ret = recv(sioc->fd,
+                   iov[i].iov_base,
+                   iov[i].iov_len,
+                   0);
+        if (ret < 0) {
+            if (socket_error() == EAGAIN) {
+                if (done) {
+                    return done;
+                } else {
+                    return QIO_CHANNEL_ERR_BLOCK;
+                }
+            } else if (socket_error() == EINTR) {
+                goto retry;
+            } else {
+                error_setg_errno(errp, socket_error(),
+                                 "Unable to write to socket");
+                return -1;
+            }
+        }
+        done += ret;
+        if (ret < iov[i].iov_len) {
+            return done;
+        }
+    }
+
+    return done;
+}
+
+static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
+                                         const struct iovec *iov,
+                                         size_t niov,
+                                         int *fds,
+                                         size_t nfds,
+                                         Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    ssize_t done = 0;
+    ssize_t i;
+
+    for (i = 0; i < niov; i++) {
+        ssize_t ret;
+    retry:
+        ret = send(sioc->fd,
+                   iov[i].iov_base,
+                   iov[i].iov_len,
+                   0);
+        if (ret < 0) {
+            if (socket_error() == EAGAIN) {
+                if (done) {
+                    return done;
+                } else {
+                    return QIO_CHANNEL_ERR_BLOCK;
+                }
+            } else if (socket_error() == EINTR) {
+                goto retry;
+            } else {
+                error_setg_errno(errp, socket_error(),
+                                 "Unable to write to socket");
+                return -1;
+            }
+        }
+        done += ret;
+        if (ret < iov[i].iov_len) {
+            return done;
+        }
+    }
+
+    return done;
+}
+#endif /* WIN32 */
+
+static int
+qio_channel_socket_set_blocking(QIOChannel *ioc,
+                                bool enabled,
+                                Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+
+    if (enabled) {
+        qemu_set_block(sioc->fd);
+    } else {
+        qemu_set_nonblock(sioc->fd);
+    }
+    return 0;
+}
+
+
+static void
+qio_channel_socket_set_delay(QIOChannel *ioc,
+                             bool enabled)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    int v = enabled ? 0 : 1;
+
+    qemu_setsockopt(sioc->fd,
+                    IPPROTO_TCP, TCP_NODELAY,
+                    &v, sizeof(v));
+}
+
+
+static void
+qio_channel_socket_set_cork(QIOChannel *ioc,
+                            bool enabled)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    int v = enabled ? 1 : 0;
+
+    socket_set_cork(sioc->fd, v);
+}
+
+
+static int
+qio_channel_socket_close(QIOChannel *ioc,
+                         Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+
+    if (closesocket(sioc->fd) < 0) {
+        sioc->fd = -1;
+        error_setg_errno(errp, socket_error(),
+                         "Unable to close socket");
+        return -1;
+    }
+    sioc->fd = -1;
+    return 0;
+}
+
+static int
+qio_channel_socket_shutdown(QIOChannel *ioc,
+                            QIOChannelShutdown how,
+                            Error **errp)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    int sockhow;
+
+    switch (how) {
+    case QIO_CHANNEL_SHUTDOWN_READ:
+        sockhow = SHUT_RD;
+        break;
+    case QIO_CHANNEL_SHUTDOWN_WRITE:
+        sockhow = SHUT_WR;
+        break;
+    case QIO_CHANNEL_SHUTDOWN_BOTH:
+    default:
+        sockhow = SHUT_RDWR;
+        break;
+    }
+
+    if (shutdown(sioc->fd, sockhow) < 0) {
+        error_setg_errno(errp, socket_error(),
+                         "Unable to shutdown socket");
+        return -1;
+    }
+    return 0;
+}
+
+static GSource *qio_channel_socket_create_watch(QIOChannel *ioc,
+                                                GIOCondition condition)
+{
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
+    return qio_channel_create_fd_watch(ioc,
+                                       sioc->fd,
+                                       condition);
+}
+
+static void qio_channel_socket_class_init(ObjectClass *klass,
+                                          void *class_data G_GNUC_UNUSED)
+{
+    QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
+
+    ioc_klass->io_writev = qio_channel_socket_writev;
+    ioc_klass->io_readv = qio_channel_socket_readv;
+    ioc_klass->io_set_blocking = qio_channel_socket_set_blocking;
+    ioc_klass->io_close = qio_channel_socket_close;
+    ioc_klass->io_shutdown = qio_channel_socket_shutdown;
+    ioc_klass->io_set_cork = qio_channel_socket_set_cork;
+    ioc_klass->io_set_delay = qio_channel_socket_set_delay;
+    ioc_klass->io_create_watch = qio_channel_socket_create_watch;
+}
+
+static const TypeInfo qio_channel_socket_info = {
+    .parent = TYPE_QIO_CHANNEL,
+    .name = TYPE_QIO_CHANNEL_SOCKET,
+    .instance_size = sizeof(QIOChannelSocket),
+    .instance_init = qio_channel_socket_init,
+    .instance_finalize = qio_channel_socket_finalize,
+    .class_init = qio_channel_socket_class_init,
+};
+
+static void qio_channel_socket_register_types(void)
+{
+    type_register_static(&qio_channel_socket_info);
+}
+
+type_init(qio_channel_socket_register_types);