/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2016 Intel Corporation
 */

#include <stdint.h>
#include <stdio.h>
#include <limits.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/queue.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>

#include <rte_log.h>

#include "fd_man.h"
#include "vhost.h"
#include "vhost_user.h"


TAILQ_HEAD(vhost_user_connection_list, vhost_user_connection);

/*
 * Every time rte_vhost_driver_register() is invoked, an associated
 * vhost_user_socket struct will be created.
 */
struct vhost_user_socket {
        struct vhost_user_connection_list conn_list;
        pthread_mutex_t conn_mutex;
        char *path;
        int socket_fd;
        struct sockaddr_un un;
        bool is_server;
        bool reconnect;
        bool iommu_support;
        bool use_builtin_virtio_net;
        bool extbuf;
        bool linearbuf;
        bool async_copy;
        bool net_compliant_ol_flags;

        /*
         * The "supported_features" indicates the feature bits the
         * vhost driver supports. The "features" indicates the feature
         * bits after the rte_vhost_driver_features_disable/enable().
         * It is also the final feature bits used for vhost-user
         * features negotiation.
         */
        uint64_t supported_features;
        uint64_t features;

        uint64_t protocol_features;

        struct rte_vdpa_device *vdpa_dev;

        struct vhost_device_ops const *notify_ops;
};

struct vhost_user_connection {
        struct vhost_user_socket *vsocket;
        int connfd;
        int vid;

        TAILQ_ENTRY(vhost_user_connection) next;
};

#define MAX_VHOST_SOCKET 1024
struct vhost_user {
        struct vhost_user_socket *vsockets[MAX_VHOST_SOCKET];
        struct fdset fdset;
        int vsocket_cnt;
        pthread_mutex_t mutex;
};

#define MAX_VIRTIO_BACKLOG 128

static void vhost_user_server_new_connection(int fd, void *data, int *remove);
static void vhost_user_read_cb(int fd, void *dat, int *remove);
static int create_unix_socket(struct vhost_user_socket *vsocket);
static int vhost_user_start_client(struct vhost_user_socket *vsocket);

static struct vhost_user vhost_user = {
        .fdset = {
                .fd = { [0 ... MAX_FDS - 1] = {-1, NULL, NULL, NULL, 0} },
                .fd_mutex = PTHREAD_MUTEX_INITIALIZER,
                .fd_pooling_mutex = PTHREAD_MUTEX_INITIALIZER,
                .num = 0
        },
        .vsocket_cnt = 0,
        .mutex = PTHREAD_MUTEX_INITIALIZER,
};

/*
 * return bytes# of read on success or negative val on failure. Update fdnum
 * with number of fds read.
 */
int
read_fd_message(int sockfd, char *buf, int buflen, int *fds, int max_fds,
                int *fd_num)
{
        struct iovec iov;
        struct msghdr msgh;
        char control[CMSG_SPACE(max_fds * sizeof(int))];
        struct cmsghdr *cmsg;
        int got_fds = 0;
        int ret;

        *fd_num = 0;

        memset(&msgh, 0, sizeof(msgh));
        iov.iov_base = buf;
        iov.iov_len  = buflen;

        msgh.msg_iov = &iov;
        msgh.msg_iovlen = 1;
        msgh.msg_control = control;
        msgh.msg_controllen = sizeof(control);

        ret = recvmsg(sockfd, &msgh, 0);
        if (ret <= 0) {
                if (ret)
                        VHOST_LOG_CONFIG(ERR, "recvmsg failed\n");
                return ret;
        }

        if (msgh.msg_flags & (MSG_TRUNC | MSG_CTRUNC)) {
                VHOST_LOG_CONFIG(ERR, "truncated msg\n");
                return -1;
        }

        for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg != NULL;
                cmsg = CMSG_NXTHDR(&msgh, cmsg)) {
                if ((cmsg->cmsg_level == SOL_SOCKET) &&
                        (cmsg->cmsg_type == SCM_RIGHTS)) {
                        got_fds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
                        *fd_num = got_fds;
                        memcpy(fds, CMSG_DATA(cmsg), got_fds * sizeof(int));
                        break;
                }
        }

        /* Clear out unused file descriptors */
        while (got_fds < max_fds)
                fds[got_fds++] = -1;

        return ret;
}

int
send_fd_message(int sockfd, char *buf, int buflen, int *fds, int fd_num)
{

        struct iovec iov;
        struct msghdr msgh;
        size_t fdsize = fd_num * sizeof(int);
        char control[CMSG_SPACE(fdsize)];
        struct cmsghdr *cmsg;
        int ret;

        memset(&msgh, 0, sizeof(msgh));
        iov.iov_base = buf;
        iov.iov_len = buflen;

        msgh.msg_iov = &iov;
        msgh.msg_iovlen = 1;

        if (fds && fd_num > 0) {
                msgh.msg_control = control;
                msgh.msg_controllen = sizeof(control);
                cmsg = CMSG_FIRSTHDR(&msgh);
                if (cmsg == NULL) {
                        VHOST_LOG_CONFIG(ERR, "cmsg == NULL\n");
                        errno = EINVAL;
                        return -1;
                }
                cmsg->cmsg_len = CMSG_LEN(fdsize);
                cmsg->cmsg_level = SOL_SOCKET;
                cmsg->cmsg_type = SCM_RIGHTS;
                memcpy(CMSG_DATA(cmsg), fds, fdsize);
        } else {
                msgh.msg_control = NULL;
                msgh.msg_controllen = 0;
        }

        do {
                ret = sendmsg(sockfd, &msgh, MSG_NOSIGNAL);
        } while (ret < 0 && errno == EINTR);

        if (ret < 0) {
                VHOST_LOG_CONFIG(ERR,  "sendmsg error\n");
                return ret;
        }

        return ret;
}

static void
vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
{
        int vid;
        size_t size;
        struct vhost_user_connection *conn;
        int ret;
        struct virtio_net *dev;

        if (vsocket == NULL)
                return;

        conn = malloc(sizeof(*conn));
        if (conn == NULL) {
                close(fd);
                return;
        }

        vid = vhost_new_device();
        if (vid == -1) {
                goto err;
        }

        size = strnlen(vsocket->path, PATH_MAX);
        vhost_set_ifname(vid, vsocket->path, size);

        vhost_setup_virtio_net(vid, vsocket->use_builtin_virtio_net,
                vsocket->net_compliant_ol_flags);

        vhost_attach_vdpa_device(vid, vsocket->vdpa_dev);

        if (vsocket->extbuf)
                vhost_enable_extbuf(vid);

        if (vsocket->linearbuf)
                vhost_enable_linearbuf(vid);

        if (vsocket->async_copy) {
                dev = get_device(vid);

                if (dev)
                        dev->async_copy = 1;
        }

        VHOST_LOG_CONFIG(INFO, "new device, handle is %d\n", vid);

        if (vsocket->notify_ops->new_connection) {
                ret = vsocket->notify_ops->new_connection(vid);
                if (ret < 0) {
                        VHOST_LOG_CONFIG(ERR,
                                "failed to add vhost user connection with fd %d\n",
                                fd);
                        goto err_cleanup;
                }
        }

        conn->connfd = fd;
        conn->vsocket = vsocket;
        conn->vid = vid;
        ret = fdset_add(&vhost_user.fdset, fd, vhost_user_read_cb,
                        NULL, conn);
        if (ret < 0) {
                VHOST_LOG_CONFIG(ERR,
                        "failed to add fd %d into vhost server fdset\n",
                        fd);

                if (vsocket->notify_ops->destroy_connection)
                        vsocket->notify_ops->destroy_connection(conn->vid);

                goto err_cleanup;
        }

        pthread_mutex_lock(&vsocket->conn_mutex);
        TAILQ_INSERT_TAIL(&vsocket->conn_list, conn, next);
        pthread_mutex_unlock(&vsocket->conn_mutex);

        fdset_pipe_notify(&vhost_user.fdset);
        return;

err_cleanup:
        vhost_destroy_device(vid);
err:
        free(conn);
        close(fd);
}

/* call back when there is new vhost-user connection from client  */
static void
vhost_user_server_new_connection(int fd, void *dat, int *remove __rte_unused)
{
        struct vhost_user_socket *vsocket = dat;

        fd = accept(fd, NULL, NULL);
        if (fd < 0)
                return;

        VHOST_LOG_CONFIG(INFO, "new vhost user connection is %d\n", fd);
        vhost_user_add_connection(fd, vsocket);
}

static void
vhost_user_read_cb(int connfd, void *dat, int *remove)
{
        struct vhost_user_connection *conn = dat;
        struct vhost_user_socket *vsocket = conn->vsocket;
        int ret;

        ret = vhost_user_msg_handler(conn->vid, connfd);
        if (ret < 0) {
                struct virtio_net *dev = get_device(conn->vid);

                close(connfd);
                *remove = 1;

                if (dev)
                        vhost_destroy_device_notify(dev);

                if (vsocket->notify_ops->destroy_connection)
                        vsocket->notify_ops->destroy_connection(conn->vid);

                vhost_destroy_device(conn->vid);

                if (vsocket->reconnect) {
                        create_unix_socket(vsocket);
                        vhost_user_start_client(vsocket);
                }

                pthread_mutex_lock(&vsocket->conn_mutex);
                TAILQ_REMOVE(&vsocket->conn_list, conn, next);
                pthread_mutex_unlock(&vsocket->conn_mutex);

                free(conn);
        }
}

static int
create_unix_socket(struct vhost_user_socket *vsocket)
{
        int fd;
        struct sockaddr_un *un = &vsocket->un;

        fd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (fd < 0)
                return -1;
        VHOST_LOG_CONFIG(INFO, "vhost-user %s: socket created, fd: %d\n",
                vsocket->is_server ? "server" : "client", fd);

        if (!vsocket->is_server && fcntl(fd, F_SETFL, O_NONBLOCK)) {
                VHOST_LOG_CONFIG(ERR,
                        "vhost-user: can't set nonblocking mode for socket, fd: "
                        "%d (%s)\n", fd, strerror(errno));
                close(fd);
                return -1;
        }

        memset(un, 0, sizeof(*un));
        un->sun_family = AF_UNIX;
        strncpy(un->sun_path, vsocket->path, sizeof(un->sun_path));
        un->sun_path[sizeof(un->sun_path) - 1] = '\0';

        vsocket->socket_fd = fd;
        return 0;
}

static int
vhost_user_start_server(struct vhost_user_socket *vsocket)
{
        int ret;
        int fd = vsocket->socket_fd;
        const char *path = vsocket->path;

        /*
         * bind () may fail if the socket file with the same name already
         * exists. But the library obviously should not delete the file
         * provided by the user, since we can not be sure that it is not
         * being used by other applications. Moreover, many applications form
         * socket names based on user input, which is prone to errors.
         *
         * The user must ensure that the socket does not exist before
         * registering the vhost driver in server mode.
         */
        ret = bind(fd, (struct sockaddr *)&vsocket->un, sizeof(vsocket->un));
        if (ret < 0) {
                VHOST_LOG_CONFIG(ERR,
                        "failed to bind to %s: %s; remove it and try again\n",
                        path, strerror(errno));
                goto err;
        }
        VHOST_LOG_CONFIG(INFO, "bind to %s\n", path);

        ret = listen(fd, MAX_VIRTIO_BACKLOG);
        if (ret < 0)
                goto err;

        ret = fdset_add(&vhost_user.fdset, fd, vhost_user_server_new_connection,
                  NULL, vsocket);
        if (ret < 0) {
                VHOST_LOG_CONFIG(ERR,
                        "failed to add listen fd %d to vhost server fdset\n",
                        fd);
                goto err;
        }

        return 0;

err:
        close(fd);
        return -1;
}

struct vhost_user_reconnect {
        struct sockaddr_un un;
        int fd;
        struct vhost_user_socket *vsocket;

        TAILQ_ENTRY(vhost_user_reconnect) next;
};

TAILQ_HEAD(vhost_user_reconnect_tailq_list, vhost_user_reconnect);
struct vhost_user_reconnect_list {
        struct vhost_user_reconnect_tailq_list head;
        pthread_mutex_t mutex;
};

static struct vhost_user_reconnect_list reconn_list;
static pthread_t reconn_tid;

static int
vhost_user_connect_nonblock(int fd, struct sockaddr *un, size_t sz)
{
        int ret, flags;

        ret = connect(fd, un, sz);
        if (ret < 0 && errno != EISCONN)
                return -1;

        flags = fcntl(fd, F_GETFL, 0);
        if (flags < 0) {
                VHOST_LOG_CONFIG(ERR,
                        "can't get flags for connfd %d\n", fd);
                return -2;
        }
        if ((flags & O_NONBLOCK) && fcntl(fd, F_SETFL, flags & ~O_NONBLOCK)) {
                VHOST_LOG_CONFIG(ERR,
                                "can't disable nonblocking on fd %d\n", fd);
                return -2;
        }
        return 0;
}

static void *
vhost_user_client_reconnect(void *arg __rte_unused)
{
        int ret;
        struct vhost_user_reconnect *reconn, *next;

        while (1) {
                pthread_mutex_lock(&reconn_list.mutex);

                /*
                 * An equal implementation of TAILQ_FOREACH_SAFE,
                 * which does not exist on all platforms.
                 */
                for (reconn = TAILQ_FIRST(&reconn_list.head);
                     reconn != NULL; reconn = next) {
                        next = TAILQ_NEXT(reconn, next);

                        ret = vhost_user_connect_nonblock(reconn->fd,
                                                (struct sockaddr *)&reconn->un,
                                                sizeof(reconn->un));
                        if (ret == -2) {
                                close(reconn->fd);
                                VHOST_LOG_CONFIG(ERR,
                                        "reconnection for fd %d failed\n",
                                        reconn->fd);
                                goto remove_fd;
                        }
                        if (ret == -1)
                                continue;

                        VHOST_LOG_CONFIG(INFO,
                                "%s: connected\n", reconn->vsocket->path);
                        vhost_user_add_connection(reconn->fd, reconn->vsocket);
remove_fd:
                        TAILQ_REMOVE(&reconn_list.head, reconn, next);
                        free(reconn);
                }

                pthread_mutex_unlock(&reconn_list.mutex);
                sleep(1);
        }

        return NULL;
}

static int
vhost_user_reconnect_init(void)
{
        int ret;

        ret = pthread_mutex_init(&reconn_list.mutex, NULL);
        if (ret < 0) {
                VHOST_LOG_CONFIG(ERR, "failed to initialize mutex");
                return ret;
        }
        TAILQ_INIT(&reconn_list.head);

        ret = rte_ctrl_thread_create(&reconn_tid, "vhost_reconn", NULL,
                             vhost_user_client_reconnect, NULL);
        if (ret != 0) {
                VHOST_LOG_CONFIG(ERR, "failed to create reconnect thread");
                if (pthread_mutex_destroy(&reconn_list.mutex)) {
                        VHOST_LOG_CONFIG(ERR,
                                "failed to destroy reconnect mutex");
                }
        }

        return ret;
}

static int
vhost_user_start_client(struct vhost_user_socket *vsocket)
{
        int ret;
        int fd = vsocket->socket_fd;
        const char *path = vsocket->path;
        struct vhost_user_reconnect *reconn;

        ret = vhost_user_connect_nonblock(fd, (struct sockaddr *)&vsocket->un,
                                          sizeof(vsocket->un));
        if (ret == 0) {
                vhost_user_add_connection(fd, vsocket);
                return 0;
        }

        VHOST_LOG_CONFIG(WARNING,
                "failed to connect to %s: %s\n",
                path, strerror(errno));

        if (ret == -2 || !vsocket->reconnect) {
                close(fd);
                return -1;
        }

        VHOST_LOG_CONFIG(INFO, "%s: reconnecting...\n", path);
        reconn = malloc(sizeof(*reconn));
        if (reconn == NULL) {
                VHOST_LOG_CONFIG(ERR,
                        "failed to allocate memory for reconnect\n");
                close(fd);
                return -1;
        }
        reconn->un = vsocket->un;
        reconn->fd = fd;
        reconn->vsocket = vsocket;
        pthread_mutex_lock(&reconn_list.mutex);
        TAILQ_INSERT_TAIL(&reconn_list.head, reconn, next);
        pthread_mutex_unlock(&reconn_list.mutex);

        return 0;
}

static struct vhost_user_socket *
find_vhost_user_socket(const char *path)
{
        int i;

        if (path == NULL)
                return NULL;

        for (i = 0; i < vhost_user.vsocket_cnt; i++) {
                struct vhost_user_socket *vsocket = vhost_user.vsockets[i];

                if (!strcmp(vsocket->path, path))
                        return vsocket;
        }

        return NULL;
}

int
rte_vhost_driver_attach_vdpa_device(const char *path,
                struct rte_vdpa_device *dev)
{
        struct vhost_user_socket *vsocket;

        if (dev == NULL || path == NULL)
                return -1;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket)
                vsocket->vdpa_dev = dev;
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? 0 : -1;
}

int
rte_vhost_driver_detach_vdpa_device(const char *path)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket)
                vsocket->vdpa_dev = NULL;
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? 0 : -1;
}

struct rte_vdpa_device *
rte_vhost_driver_get_vdpa_device(const char *path)
{
        struct vhost_user_socket *vsocket;
        struct rte_vdpa_device *dev = NULL;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket)
                dev = vsocket->vdpa_dev;
        pthread_mutex_unlock(&vhost_user.mutex);

        return dev;
}

int
rte_vhost_driver_disable_features(const char *path, uint64_t features)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);

        /* Note that use_builtin_virtio_net is not affected by this function
         * since callers may want to selectively disable features of the
         * built-in vhost net device backend.
         */

        if (vsocket)
                vsocket->features &= ~features;
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? 0 : -1;
}

int
rte_vhost_driver_enable_features(const char *path, uint64_t features)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket) {
                if ((vsocket->supported_features & features) != features) {
                        /*
                         * trying to enable features the driver doesn't
                         * support.
                         */
                        pthread_mutex_unlock(&vhost_user.mutex);
                        return -1;
                }
                vsocket->features |= features;
        }
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? 0 : -1;
}

int
rte_vhost_driver_set_features(const char *path, uint64_t features)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket) {
                vsocket->supported_features = features;
                vsocket->features = features;

                /* Anyone setting feature bits is implementing their own vhost
                 * device backend.
                 */
                vsocket->use_builtin_virtio_net = false;
        }
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? 0 : -1;
}

int
rte_vhost_driver_get_features(const char *path, uint64_t *features)
{
        struct vhost_user_socket *vsocket;
        uint64_t vdpa_features;
        struct rte_vdpa_device *vdpa_dev;
        int ret = 0;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (!vsocket) {
                VHOST_LOG_CONFIG(ERR,
                        "socket file %s is not registered yet.\n", path);
                ret = -1;
                goto unlock_exit;
        }

        vdpa_dev = vsocket->vdpa_dev;
        if (!vdpa_dev) {
                *features = vsocket->features;
                goto unlock_exit;
        }

        if (vdpa_dev->ops->get_features(vdpa_dev, &vdpa_features) < 0) {
                VHOST_LOG_CONFIG(ERR,
                                "failed to get vdpa features "
                                "for socket file %s.\n", path);
                ret = -1;
                goto unlock_exit;
        }

        *features = vsocket->features & vdpa_features;

unlock_exit:
        pthread_mutex_unlock(&vhost_user.mutex);
        return ret;
}

int
rte_vhost_driver_set_protocol_features(const char *path,
                uint64_t protocol_features)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket)
                vsocket->protocol_features = protocol_features;
        pthread_mutex_unlock(&vhost_user.mutex);
        return vsocket ? 0 : -1;
}

int
rte_vhost_driver_get_protocol_features(const char *path,
                uint64_t *protocol_features)
{
        struct vhost_user_socket *vsocket;
        uint64_t vdpa_protocol_features;
        struct rte_vdpa_device *vdpa_dev;
        int ret = 0;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (!vsocket) {
                VHOST_LOG_CONFIG(ERR,
                        "socket file %s is not registered yet.\n", path);
                ret = -1;
                goto unlock_exit;
        }

        vdpa_dev = vsocket->vdpa_dev;
        if (!vdpa_dev) {
                *protocol_features = vsocket->protocol_features;
                goto unlock_exit;
        }

        if (vdpa_dev->ops->get_protocol_features(vdpa_dev,
                                &vdpa_protocol_features) < 0) {
                VHOST_LOG_CONFIG(ERR,
                                "failed to get vdpa protocol features "
                                "for socket file %s.\n", path);
                ret = -1;
                goto unlock_exit;
        }

        *protocol_features = vsocket->protocol_features
                & vdpa_protocol_features;

unlock_exit:
        pthread_mutex_unlock(&vhost_user.mutex);
        return ret;
}

int
rte_vhost_driver_get_queue_num(const char *path, uint32_t *queue_num)
{
        struct vhost_user_socket *vsocket;
        uint32_t vdpa_queue_num;
        struct rte_vdpa_device *vdpa_dev;
        int ret = 0;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (!vsocket) {
                VHOST_LOG_CONFIG(ERR,
                        "socket file %s is not registered yet.\n", path);
                ret = -1;
                goto unlock_exit;
        }

        vdpa_dev = vsocket->vdpa_dev;
        if (!vdpa_dev) {
                *queue_num = VHOST_MAX_QUEUE_PAIRS;
                goto unlock_exit;
        }

        if (vdpa_dev->ops->get_queue_num(vdpa_dev, &vdpa_queue_num) < 0) {
                VHOST_LOG_CONFIG(ERR,
                                "failed to get vdpa queue number "
                                "for socket file %s.\n", path);
                ret = -1;
                goto unlock_exit;
        }

        *queue_num = RTE_MIN((uint32_t)VHOST_MAX_QUEUE_PAIRS, vdpa_queue_num);

unlock_exit:
        pthread_mutex_unlock(&vhost_user.mutex);
        return ret;
}

static void
vhost_user_socket_mem_free(struct vhost_user_socket *vsocket)
{
        if (vsocket && vsocket->path) {
                free(vsocket->path);
                vsocket->path = NULL;
        }

        if (vsocket) {
                free(vsocket);
                vsocket = NULL;
        }
}

/*
 * Register a new vhost-user socket; here we could act as server
 * (the default case), or client (when RTE_VHOST_USER_CLIENT) flag
 * is set.
 */
int
rte_vhost_driver_register(const char *path, uint64_t flags)
{
        int ret = -1;
        struct vhost_user_socket *vsocket;

        if (!path)
                return -1;

        pthread_mutex_lock(&vhost_user.mutex);

        if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
                VHOST_LOG_CONFIG(ERR,
                        "error: the number of vhost sockets reaches maximum\n");
                goto out;
        }

        vsocket = malloc(sizeof(struct vhost_user_socket));
        if (!vsocket)
                goto out;
        memset(vsocket, 0, sizeof(struct vhost_user_socket));
        vsocket->path = strdup(path);
        if (vsocket->path == NULL) {
                VHOST_LOG_CONFIG(ERR,
                        "error: failed to copy socket path string\n");
                vhost_user_socket_mem_free(vsocket);
                goto out;
        }
        TAILQ_INIT(&vsocket->conn_list);
        ret = pthread_mutex_init(&vsocket->conn_mutex, NULL);
        if (ret) {
                VHOST_LOG_CONFIG(ERR,
                        "error: failed to init connection mutex\n");
                goto out_free;
        }
        vsocket->vdpa_dev = NULL;
        vsocket->extbuf = flags & RTE_VHOST_USER_EXTBUF_SUPPORT;
        vsocket->linearbuf = flags & RTE_VHOST_USER_LINEARBUF_SUPPORT;
        vsocket->async_copy = flags & RTE_VHOST_USER_ASYNC_COPY;
        vsocket->net_compliant_ol_flags = flags & RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;

        if (vsocket->async_copy &&
                (flags & (RTE_VHOST_USER_IOMMU_SUPPORT |
                RTE_VHOST_USER_POSTCOPY_SUPPORT))) {
                VHOST_LOG_CONFIG(ERR, "error: enabling async copy and IOMMU "
                        "or post-copy feature simultaneously is not "
                        "supported\n");
                goto out_mutex;
        }

        /*
         * Set the supported features correctly for the builtin vhost-user
         * net driver.
         *
         * Applications know nothing about features the builtin virtio net
         * driver (virtio_net.c) supports, thus it's not possible for them
         * to invoke rte_vhost_driver_set_features(). To workaround it, here
         * we set it unconditionally. If the application want to implement
         * another vhost-user driver (say SCSI), it should call the
         * rte_vhost_driver_set_features(), which will overwrite following
         * two values.
         */
        vsocket->use_builtin_virtio_net = true;
        vsocket->supported_features = VIRTIO_NET_SUPPORTED_FEATURES;
        vsocket->features           = VIRTIO_NET_SUPPORTED_FEATURES;
        vsocket->protocol_features  = VHOST_USER_PROTOCOL_FEATURES;

        if (vsocket->async_copy) {
                vsocket->supported_features &= ~(1ULL << VHOST_F_LOG_ALL);
                vsocket->features &= ~(1ULL << VHOST_F_LOG_ALL);
                VHOST_LOG_CONFIG(INFO,
                        "Logging feature is disabled in async copy mode\n");
        }

        /*
         * We'll not be able to receive a buffer from guest in linear mode
         * without external buffer if it will not fit in a single mbuf, which is
         * likely if segmentation offloading enabled.
         */
        if (vsocket->linearbuf && !vsocket->extbuf) {
                uint64_t seg_offload_features =
                                (1ULL << VIRTIO_NET_F_HOST_TSO4) |
                                (1ULL << VIRTIO_NET_F_HOST_TSO6) |
                                (1ULL << VIRTIO_NET_F_HOST_UFO);

                VHOST_LOG_CONFIG(INFO,
                        "Linear buffers requested without external buffers, "
                        "disabling host segmentation offloading support\n");
                vsocket->supported_features &= ~seg_offload_features;
                vsocket->features &= ~seg_offload_features;
        }

        if (!(flags & RTE_VHOST_USER_IOMMU_SUPPORT)) {
                vsocket->supported_features &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
                vsocket->features &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
        }

        if (!(flags & RTE_VHOST_USER_POSTCOPY_SUPPORT)) {
                vsocket->protocol_features &=
                        ~(1ULL << VHOST_USER_PROTOCOL_F_PAGEFAULT);
        } else {
#ifndef RTE_LIBRTE_VHOST_POSTCOPY
                VHOST_LOG_CONFIG(ERR,
                        "Postcopy requested but not compiled\n");
                ret = -1;
                goto out_mutex;
#endif
        }

        if ((flags & RTE_VHOST_USER_CLIENT) != 0) {
                vsocket->reconnect = !(flags & RTE_VHOST_USER_NO_RECONNECT);
                if (vsocket->reconnect && reconn_tid == 0) {
                        if (vhost_user_reconnect_init() != 0)
                                goto out_mutex;
                }
        } else {
                vsocket->is_server = true;
        }
        ret = create_unix_socket(vsocket);
        if (ret < 0) {
                goto out_mutex;
        }

        vhost_user.vsockets[vhost_user.vsocket_cnt++] = vsocket;

        pthread_mutex_unlock(&vhost_user.mutex);
        return ret;

out_mutex:
        if (pthread_mutex_destroy(&vsocket->conn_mutex)) {
                VHOST_LOG_CONFIG(ERR,
                        "error: failed to destroy connection mutex\n");
        }
out_free:
        vhost_user_socket_mem_free(vsocket);
out:
        pthread_mutex_unlock(&vhost_user.mutex);

        return ret;
}

static bool
vhost_user_remove_reconnect(struct vhost_user_socket *vsocket)
{
        int found = false;
        struct vhost_user_reconnect *reconn, *next;

        pthread_mutex_lock(&reconn_list.mutex);

        for (reconn = TAILQ_FIRST(&reconn_list.head);
             reconn != NULL; reconn = next) {
                next = TAILQ_NEXT(reconn, next);

                if (reconn->vsocket == vsocket) {
                        TAILQ_REMOVE(&reconn_list.head, reconn, next);
                        close(reconn->fd);
                        free(reconn);
                        found = true;

                        break;
                }
        }
        pthread_mutex_unlock(&reconn_list.mutex);
        return found;
}

/**
 * Unregister the specified vhost socket
 */
int
rte_vhost_driver_unregister(const char *path)
{
        int i;
        int count;
        struct vhost_user_connection *conn, *next;

        if (path == NULL)
                return -1;

again:
        pthread_mutex_lock(&vhost_user.mutex);

        for (i = 0; i < vhost_user.vsocket_cnt; i++) {
                struct vhost_user_socket *vsocket = vhost_user.vsockets[i];

                if (!strcmp(vsocket->path, path)) {
                        pthread_mutex_lock(&vsocket->conn_mutex);
                        for (conn = TAILQ_FIRST(&vsocket->conn_list);
                             conn != NULL;
                             conn = next) {
                                next = TAILQ_NEXT(conn, next);

                                /*
                                 * If r/wcb is executing, release vsocket's
                                 * conn_mutex and vhost_user's mutex locks, and
                                 * try again since the r/wcb may use the
                                 * conn_mutex and mutex locks.
                                 */
                                if (fdset_try_del(&vhost_user.fdset,
                                                  conn->connfd) == -1) {
                                        pthread_mutex_unlock(
                                                        &vsocket->conn_mutex);
                                        pthread_mutex_unlock(&vhost_user.mutex);
                                        goto again;
                                }

                                VHOST_LOG_CONFIG(INFO,
                                        "free connfd = %d for device '%s'\n",
                                        conn->connfd, path);
                                close(conn->connfd);
                                vhost_destroy_device(conn->vid);
                                TAILQ_REMOVE(&vsocket->conn_list, conn, next);
                                free(conn);
                        }
                        pthread_mutex_unlock(&vsocket->conn_mutex);

                        if (vsocket->is_server) {
                                /*
                                 * If r/wcb is executing, release vhost_user's
                                 * mutex lock, and try again since the r/wcb
                                 * may use the mutex lock.
                                 */
                                if (fdset_try_del(&vhost_user.fdset,
                                                vsocket->socket_fd) == -1) {
                                        pthread_mutex_unlock(&vhost_user.mutex);
                                        goto again;
                                }

                                close(vsocket->socket_fd);
                                unlink(path);
                        } else if (vsocket->reconnect) {
                                vhost_user_remove_reconnect(vsocket);
                        }

                        pthread_mutex_destroy(&vsocket->conn_mutex);
                        vhost_user_socket_mem_free(vsocket);

                        count = --vhost_user.vsocket_cnt;
                        vhost_user.vsockets[i] = vhost_user.vsockets[count];
                        vhost_user.vsockets[count] = NULL;
                        pthread_mutex_unlock(&vhost_user.mutex);

                        return 0;
                }
        }
        pthread_mutex_unlock(&vhost_user.mutex);

        return -1;
}

/*
 * Register ops so that we can add/remove device to data core.
 */
int
rte_vhost_driver_callback_register(const char *path,
        struct vhost_device_ops const * const ops)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        if (vsocket)
                vsocket->notify_ops = ops;
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? 0 : -1;
}

struct vhost_device_ops const *
vhost_driver_callback_get(const char *path)
{
        struct vhost_user_socket *vsocket;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        pthread_mutex_unlock(&vhost_user.mutex);

        return vsocket ? vsocket->notify_ops : NULL;
}

int
rte_vhost_driver_start(const char *path)
{
        struct vhost_user_socket *vsocket;
        static pthread_t fdset_tid;

        pthread_mutex_lock(&vhost_user.mutex);
        vsocket = find_vhost_user_socket(path);
        pthread_mutex_unlock(&vhost_user.mutex);

        if (!vsocket)
                return -1;

        if (fdset_tid == 0) {
                /**
                 * create a pipe which will be waited by poll and notified to
                 * rebuild the wait list of poll.
                 */
                if (fdset_pipe_init(&vhost_user.fdset) < 0) {
                        VHOST_LOG_CONFIG(ERR,
                                "failed to create pipe for vhost fdset\n");
                        return -1;
                }

                int ret = rte_ctrl_thread_create(&fdset_tid,
                        "vhost-events", NULL, fdset_event_dispatch,
                        &vhost_user.fdset);
                if (ret != 0) {
                        VHOST_LOG_CONFIG(ERR,
                                "failed to create fdset handling thread");

                        fdset_pipe_uninit(&vhost_user.fdset);
                        return -1;
                }
        }

        if (vsocket->is_server)
                return vhost_user_start_server(vsocket);
        else
                return vhost_user_start_client(vsocket);
}