net/socket.c

/*
 * QEMU System Emulator
 *
 * Copyright (c) 2003-2008 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "qemu/osdep.h"

#include "net/net.h"
#include "clients.h"
#include "monitor/monitor.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/option.h"
#include "qemu/sockets.h"
#include "qemu/iov.h"
#include "qemu/main-loop.h"

typedef struct NetSocketState {
    NetClientState nc;
    int listen_fd;
    int fd;
    SocketReadState rs;
    unsigned int send_index;      /* number of bytes sent (only SOCK_STREAM) */
    struct sockaddr_in dgram_dst; /* contains inet host and port destination iff connectionless (SOCK_DGRAM) */
    IOHandler *send_fn;           /* differs between SOCK_STREAM/SOCK_DGRAM */
    bool read_poll;               /* waiting to receive data? */
    bool write_poll;              /* waiting to transmit data? */
} NetSocketState;

static void net_socket_accept(void *opaque);
static void net_socket_writable(void *opaque);

static void net_socket_update_fd_handler(NetSocketState *s)
{
    qemu_set_fd_handler(s->fd,
                        s->read_poll ? s->send_fn : NULL,
                        s->write_poll ? net_socket_writable : NULL,
                        s);
}

static void net_socket_read_poll(NetSocketState *s, bool enable)
{
    s->read_poll = enable;
    net_socket_update_fd_handler(s);
}

static void net_socket_write_poll(NetSocketState *s, bool enable)
{
    s->write_poll = enable;
    net_socket_update_fd_handler(s);
}

static void net_socket_writable(void *opaque)
{
    NetSocketState *s = opaque;

    net_socket_write_poll(s, false);

    qemu_flush_queued_packets(&s->nc);
}

static ssize_t net_socket_receive(NetClientState *nc, const uint8_t *buf, size_t size)
{
    NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);
    uint32_t len = htonl(size);
    struct iovec iov[] = {
        {
            .iov_base = &len,
            .iov_len  = sizeof(len),
        }, {
            .iov_base = (void *)buf,
            .iov_len  = size,
        },
    };
    size_t remaining;
    ssize_t ret;

    remaining = iov_size(iov, 2) - s->send_index;
    ret = iov_send(s->fd, iov, 2, s->send_index, remaining);

    if (ret == -1 && errno == EAGAIN) {
        ret = 0; /* handled further down */
    }
    if (ret == -1) {
        s->send_index = 0;
        return -errno;
    }
    if (ret < (ssize_t)remaining) {
        s->send_index += ret;
        net_socket_write_poll(s, true);
        return 0;
    }
    s->send_index = 0;
    return size;
}

static ssize_t net_socket_receive_dgram(NetClientState *nc, const uint8_t *buf, size_t size)
{
    NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);
    ssize_t ret;

    ret = RETRY_ON_EINTR(
        s->dgram_dst.sin_family != AF_UNIX ?
            sendto(s->fd, buf, size, 0,
                     (struct sockaddr *)&s->dgram_dst,
                     sizeof(s->dgram_dst)) :
            send(s->fd, buf, size, 0)
    );

    if (ret == -1 && errno == EAGAIN) {
        net_socket_write_poll(s, true);
        return 0;
    }
    return ret;
}

static void net_socket_send_completed(NetClientState *nc, ssize_t len)
{
    NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);

    if (!s->read_poll) {
        net_socket_read_poll(s, true);
    }
}

static void net_socket_rs_finalize(SocketReadState *rs)
{
    NetSocketState *s = container_of(rs, NetSocketState, rs);

    if (qemu_send_packet_async(&s->nc, rs->buf,
                               rs->packet_len,
                               net_socket_send_completed) == 0) {
        net_socket_read_poll(s, false);
    }
}

static void net_socket_send(void *opaque)
{
    NetSocketState *s = opaque;
    int size;
    int ret;
    QEMU_UNINITIALIZED uint8_t buf1[NET_BUFSIZE];
    const uint8_t *buf;

    size = recv(s->fd, buf1, sizeof(buf1), 0);
    if (size < 0) {
        if (errno != EWOULDBLOCK)
            goto eoc;
    } else if (size == 0) {
        /* end of connection */
    eoc:
        net_socket_read_poll(s, false);
        net_socket_write_poll(s, false);
        if (s->listen_fd != -1) {
            qemu_set_fd_handler(s->listen_fd, net_socket_accept, NULL, s);
        }
        close(s->fd);

        s->fd = -1;
        net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
        s->nc.link_down = true;
        qemu_set_info_str(&s->nc, "%s", "");

        return;
    }
    buf = buf1;

    ret = net_fill_rstate(&s->rs, buf, size);

    if (ret == -1) {
        goto eoc;
    }
}

static void net_socket_send_dgram(void *opaque)
{
    NetSocketState *s = opaque;
    int size;

    size = recv(s->fd, s->rs.buf, sizeof(s->rs.buf), 0);
    if (size < 0)
        return;
    if (size == 0) {
        /* end of connection */
        net_socket_read_poll(s, false);
        net_socket_write_poll(s, false);
        return;
    }
    if (qemu_send_packet_async(&s->nc, s->rs.buf, size,
                               net_socket_send_completed) == 0) {
        net_socket_read_poll(s, false);
    }
}

static int net_socket_mcast_create(struct sockaddr_in *mcastaddr,
                                   struct in_addr *localaddr,
                                   Error **errp)
{
    struct ip_mreq imr;
    int fd;
    int val, ret;
#ifdef __OpenBSD__
    unsigned char loop;
#else
    int loop;
#endif

    if (!IN_MULTICAST(ntohl(mcastaddr->sin_addr.s_addr))) {
        error_setg(errp, "specified mcastaddr %s (0x%08x) "
                   "does not contain a multicast address",
                   inet_ntoa(mcastaddr->sin_addr),
                   (int)ntohl(mcastaddr->sin_addr.s_addr));
        return -1;
    }

    fd = qemu_socket(PF_INET, SOCK_DGRAM, 0);
    if (fd < 0) {
        error_setg_errno(errp, errno, "can't create datagram socket");
        return -1;
    }

    /* Allow multiple sockets to bind the same multicast ip and port by setting
     * SO_REUSEADDR. This is the only situation where SO_REUSEADDR should be set
     * on windows. Use socket_set_fast_reuse otherwise as it sets SO_REUSEADDR
     * only on posix systems.
     */
    val = 1;
    ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
    if (ret < 0) {
        error_setg_errno(errp, errno,
                         "can't set socket option SO_REUSEADDR");
        goto fail;
    }

    ret = bind(fd, (struct sockaddr *)mcastaddr, sizeof(*mcastaddr));
    if (ret < 0) {
        error_setg_errno(errp, errno, "can't bind ip=%s to socket",
                         inet_ntoa(mcastaddr->sin_addr));
        goto fail;
    }

    /* Add host to multicast group */
    imr.imr_multiaddr = mcastaddr->sin_addr;
    if (localaddr) {
        imr.imr_interface = *localaddr;
    } else {
        imr.imr_interface.s_addr = htonl(INADDR_ANY);
    }

    ret = setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                     &imr, sizeof(struct ip_mreq));
    if (ret < 0) {
        error_setg_errno(errp, errno,
                         "can't add socket to multicast group %s",
                         inet_ntoa(imr.imr_multiaddr));
        goto fail;
    }

    /* Force mcast msgs to loopback (eg. several QEMUs in same host */
    loop = 1;
    ret = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP,
                     &loop, sizeof(loop));
    if (ret < 0) {
        error_setg_errno(errp, errno,
                         "can't force multicast message to loopback");
        goto fail;
    }

    /* If a bind address is given, only send packets from that address */
    if (localaddr != NULL) {
        ret = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF,
                         localaddr, sizeof(*localaddr));
        if (ret < 0) {
            error_setg_errno(errp, errno,
                             "can't set the default network send interface");
            goto fail;
        }
    }

    qemu_socket_set_nonblock(fd);
    return fd;
fail:
    if (fd >= 0)
        close(fd);
    return -1;
}

static void net_socket_cleanup(NetClientState *nc)
{
    NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);
    if (s->fd != -1) {
        net_socket_read_poll(s, false);
        net_socket_write_poll(s, false);
        close(s->fd);
        s->fd = -1;
    }
    if (s->listen_fd != -1) {
        qemu_set_fd_handler(s->listen_fd, NULL, NULL, NULL);
        close(s->listen_fd);
        s->listen_fd = -1;
    }
}

static NetClientInfo net_dgram_socket_info = {
    .type = NET_CLIENT_DRIVER_SOCKET,
    .size = sizeof(NetSocketState),
    .receive = net_socket_receive_dgram,
    .cleanup = net_socket_cleanup,
};

static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
                                                const char *model,
                                                const char *name,
                                                int fd, int is_connected,
                                                const char *mcast,
                                                Error **errp)
{
    struct sockaddr_in saddr;
    int newfd;
    NetClientState *nc;
    NetSocketState *s;
    SocketAddress *sa;
    SocketAddressType sa_type;

    sa = socket_local_address(fd, errp);
    if (!sa) {
        return NULL;
    }
    sa_type = sa->type;
    qapi_free_SocketAddress(sa);

    /* fd passed: multicast: "learn" dgram_dst address from bound address and save it
     * Because this may be "shared" socket from a "master" process, datagrams would be recv()
     * by ONLY ONE process: we must "clone" this dgram socket --jjo
     */

    if (is_connected && mcast != NULL) {
            if (parse_host_port(&saddr, mcast, errp) < 0) {
                goto err;
            }
            /* must be bound */
            if (saddr.sin_addr.s_addr == 0) {
                error_setg(errp, "can't setup multicast destination address");
                goto err;
            }
            /* clone dgram socket */
            newfd = net_socket_mcast_create(&saddr, NULL, errp);
            if (newfd < 0) {
                goto err;
            }
            /* clone newfd to fd, close newfd */
            dup2(newfd, fd);
            close(newfd);

    }

    nc = qemu_new_net_client(&net_dgram_socket_info, peer, model, name);

    s = DO_UPCAST(NetSocketState, nc, nc);

    s->fd = fd;
    s->listen_fd = -1;
    s->send_fn = net_socket_send_dgram;
    net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
    net_socket_read_poll(s, true);

    /* mcast: save bound address as dst */
    if (is_connected && mcast != NULL) {
        s->dgram_dst = saddr;
        qemu_set_info_str(nc, "socket: fd=%d (cloned mcast=%s:%d)", fd,
                          inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
    } else {
        if (sa_type == SOCKET_ADDRESS_TYPE_UNIX) {
            s->dgram_dst.sin_family = AF_UNIX;
        }

        qemu_set_info_str(nc, "socket: fd=%d %s", fd,
                          SocketAddressType_str(sa_type));
    }

    return s;

err:
    close(fd);
    return NULL;
}

static void net_socket_connect(void *opaque)
{
    NetSocketState *s = opaque;
    s->send_fn = net_socket_send;
    net_socket_read_poll(s, true);
}

static NetClientInfo net_socket_info = {
    .type = NET_CLIENT_DRIVER_SOCKET,
    .size = sizeof(NetSocketState),
    .receive = net_socket_receive,
    .cleanup = net_socket_cleanup,
};

static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
                                                 const char *model,
                                                 const char *name,
                                                 int fd, int is_connected)
{
    NetClientState *nc;
    NetSocketState *s;

    nc = qemu_new_net_client(&net_socket_info, peer, model, name);

    qemu_set_info_str(nc, "socket: fd=%d", fd);

    s = DO_UPCAST(NetSocketState, nc, nc);

    s->fd = fd;
    s->listen_fd = -1;
    net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);

    /* Disable Nagle algorithm on TCP sockets to reduce latency */
    socket_set_nodelay(fd);

    if (is_connected) {
        net_socket_connect(s);
    } else {
        qemu_set_fd_handler(s->fd, NULL, net_socket_connect, s);
    }
    return s;
}

static int net_socket_fd_check(int fd, Error **errp)
{
    int so_type, optlen = sizeof(so_type);

    if (getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&so_type,
        (socklen_t *)&optlen) < 0) {
        error_setg(errp, "can't get socket option SO_TYPE");
        return -1;
    }
    if (so_type != SOCK_DGRAM && so_type != SOCK_STREAM) {
        error_setg(errp, "socket type=%d for fd=%d must be either"
                   " SOCK_DGRAM or SOCK_STREAM", so_type, fd);
        return -1;
    }
    return so_type;
}

static void net_socket_accept(void *opaque)
{
    NetSocketState *s = opaque;
    struct sockaddr_in saddr;
    socklen_t len;
    int fd;

    for(;;) {
        len = sizeof(saddr);
        fd = qemu_accept(s->listen_fd, (struct sockaddr *)&saddr, &len);
        if (fd < 0 && errno != EINTR) {
            return;
        } else if (fd >= 0) {
            qemu_set_fd_handler(s->listen_fd, NULL, NULL, NULL);
            break;
        }
    }

    s->fd = fd;
    s->nc.link_down = false;
    net_socket_connect(s);
    qemu_set_info_str(&s->nc, "socket: connection from %s:%d",
                      inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
}

static int net_socket_listen_init(NetClientState *peer,
                                  const char *model,
                                  const char *name,
                                  const char *host_str,
                                  Error **errp)
{
    NetClientState *nc;
    NetSocketState *s;
    struct sockaddr_in saddr;
    int fd, ret;

    if (parse_host_port(&saddr, host_str, errp) < 0) {
        return -1;
    }

    fd = qemu_socket(PF_INET, SOCK_STREAM, 0);
    if (fd < 0) {
        error_setg_errno(errp, errno, "can't create stream socket");
        return -1;
    }
    qemu_socket_set_nonblock(fd);

    socket_set_fast_reuse(fd);

    ret = bind(fd, (struct sockaddr *)&saddr, sizeof(saddr));
    if (ret < 0) {
        error_setg_errno(errp, errno, "can't bind ip=%s to socket",
                         inet_ntoa(saddr.sin_addr));
        close(fd);
        return -1;
    }
    ret = listen(fd, 0);
    if (ret < 0) {
        error_setg_errno(errp, errno, "can't listen on socket");
        close(fd);
        return -1;
    }

    nc = qemu_new_net_client(&net_socket_info, peer, model, name);
    s = DO_UPCAST(NetSocketState, nc, nc);
    s->fd = -1;
    s->listen_fd = fd;
    s->nc.link_down = true;
    net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);

    qemu_set_fd_handler(s->listen_fd, net_socket_accept, NULL, s);
    return 0;
}

static int net_socket_connect_init(NetClientState *peer,
                                   const char *model,
                                   const char *name,
                                   const char *host_str,
                                   Error **errp)
{
    NetSocketState *s;
    int fd, connected, ret;
    struct sockaddr_in saddr;

    if (parse_host_port(&saddr, host_str, errp) < 0) {
        return -1;
    }

    fd = qemu_socket(PF_INET, SOCK_STREAM, 0);
    if (fd < 0) {
        error_setg_errno(errp, errno, "can't create stream socket");
        return -1;
    }
    qemu_socket_set_nonblock(fd);

    connected = 0;
    for(;;) {
        ret = connect(fd, (struct sockaddr *)&saddr, sizeof(saddr));
        if (ret < 0) {
            if (errno == EINTR || errno == EWOULDBLOCK) {
                /* continue */
            } else if (errno == EINPROGRESS ||
                       errno == EALREADY) {
                break;
            } else {
                error_setg_errno(errp, errno, "can't connect socket");
                close(fd);
                return -1;
            }
        } else {
            connected = 1;
            break;
        }
    }
    s = net_socket_fd_init_stream(peer, model, name, fd, connected);
    if (!s) {
        return -1;
    }

    qemu_set_info_str(&s->nc, "socket: connect to %s:%d",
                      inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
    return 0;
}

static int net_socket_mcast_init(NetClientState *peer,
                                 const char *model,
                                 const char *name,
                                 const char *host_str,
                                 const char *localaddr_str,
                                 Error **errp)
{
    NetSocketState *s;
    int fd;
    struct sockaddr_in saddr;
    struct in_addr localaddr, *param_localaddr;

    if (parse_host_port(&saddr, host_str, errp) < 0) {
        return -1;
    }

    if (localaddr_str != NULL) {
        if (inet_aton(localaddr_str, &localaddr) == 0) {
            error_setg(errp, "localaddr '%s' is not a valid IPv4 address",
                       localaddr_str);
            return -1;
        }
        param_localaddr = &localaddr;
    } else {
        param_localaddr = NULL;
    }

    fd = net_socket_mcast_create(&saddr, param_localaddr, errp);
    if (fd < 0) {
        return -1;
    }

    s = net_socket_fd_init_dgram(peer, model, name, fd, 0, NULL, errp);
    if (!s) {
        return -1;
    }

    s->dgram_dst = saddr;

    qemu_set_info_str(&s->nc, "socket: mcast=%s:%d",
                      inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
    return 0;

}

static int net_socket_udp_init(NetClientState *peer,
                                 const char *model,
                                 const char *name,
                                 const char *rhost,
                                 const char *lhost,
                                 Error **errp)
{
    NetSocketState *s;
    int fd, ret;
    struct sockaddr_in laddr, raddr;

    if (parse_host_port(&laddr, lhost, errp) < 0) {
        return -1;
    }

    if (parse_host_port(&raddr, rhost, errp) < 0) {
        return -1;
    }

    fd = qemu_socket(PF_INET, SOCK_DGRAM, 0);
    if (fd < 0) {
        error_setg_errno(errp, errno, "can't create datagram socket");
        return -1;
    }

    ret = socket_set_fast_reuse(fd);
    if (ret < 0) {
        error_setg_errno(errp, errno,
                         "can't set socket option SO_REUSEADDR");
        close(fd);
        return -1;
    }
    ret = bind(fd, (struct sockaddr *)&laddr, sizeof(laddr));
    if (ret < 0) {
        error_setg_errno(errp, errno, "can't bind ip=%s to socket",
                         inet_ntoa(laddr.sin_addr));
        close(fd);
        return -1;
    }
    qemu_socket_set_nonblock(fd);

    s = net_socket_fd_init_dgram(peer, model, name, fd, 0, NULL, errp);
    if (!s) {
        return -1;
    }

    s->dgram_dst = raddr;

    qemu_set_info_str(&s->nc, "socket: udp=%s:%d", inet_ntoa(raddr.sin_addr),
                      ntohs(raddr.sin_port));
    return 0;
}

int net_init_socket(const Netdev *netdev, const char *name,
                    NetClientState *peer, Error **errp)
{
    const NetdevSocketOptions *sock;

    assert(netdev->type == NET_CLIENT_DRIVER_SOCKET);
    sock = &netdev->u.socket;

    if (!!sock->fd + !!sock->listen + !!sock->connect + !!sock->mcast +
        !!sock->udp != 1) {
        error_setg(errp, "exactly one of listen=, connect=, mcast= or udp="
                   " is required");
        return -1;
    }

    if (sock->localaddr && !sock->mcast && !sock->udp) {
        error_setg(errp, "localaddr= is only valid with mcast= or udp=");
        return -1;
    }

    if (sock->fd) {
        int fd, ret, so_type;

        fd = monitor_fd_param(monitor_cur(), sock->fd, errp);
        if (fd == -1) {
            return -1;
        }
        so_type = net_socket_fd_check(fd, errp);
        if (so_type < 0) {
            return -1;
        }
        ret = qemu_socket_try_set_nonblock(fd);
        if (ret < 0) {
            error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
                             name, fd);
            return -1;
        }
        switch (so_type) {
        case SOCK_DGRAM:
            if (!net_socket_fd_init_dgram(peer, "socket", name, fd, 1,
                                          sock->mcast, errp)) {
                return -1;
            }
            break;
        case SOCK_STREAM:
            if (!net_socket_fd_init_stream(peer, "socket", name, fd, 1)) {
                return -1;
            }
            break;
        }
        return 0;
    }

    if (sock->listen) {
        if (net_socket_listen_init(peer, "socket", name, sock->listen, errp)
            < 0) {
            return -1;
        }
        return 0;
    }

    if (sock->connect) {
        if (net_socket_connect_init(peer, "socket", name, sock->connect, errp)
            < 0) {
            return -1;
        }
        return 0;
    }

    if (sock->mcast) {
        /* if sock->localaddr is missing, it has been initialized to "all bits
         * zero" */
        if (net_socket_mcast_init(peer, "socket", name, sock->mcast,
                                  sock->localaddr, errp) < 0) {
            return -1;
        }
        return 0;
    }

    assert(sock->udp);
    if (!sock->localaddr) {
        error_setg(errp, "localaddr= is mandatory with udp=");
        return -1;
    }
    if (net_socket_udp_init(peer, "socket", name, sock->udp, sock->localaddr,
                            errp) < 0) {
        return -1;
    }
    return 0;
}