Re: [Qemu-devel] [PATCH 2/4] net: fix -netdev socket, fd= for UDP sockets

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jul 21, 2017 at 11:55:51AM +0200, Jens Freimann wrote:
> This patch fixes -netdev socket,fd= for UDP sockets
> Currently -netdev socket,fd=<...> results in
> 
>   qemu: error: specified mcastaddr "127.0.0.1" (0x7f000001) does not
>     contain a multicast address
>   qemu-system-x86_64: -netdev
>     socket,id=n1,fd=3: Device 'socket' could not be initialized
> 
> To fix these we need to allow specifying multicast and fd arguments
> for the same netdev. With this the user can specify "-netdev
> fd=3,mcast=<IP:port>"
> 
> Fixes: 3d830459b1eccdb61b75e2712fd364012ce5a115
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  net/socket.c | 37 ++++++++++++++++++-------------------
>  1 file changed, 18 insertions(+), 19 deletions(-)
> 
> diff --git a/net/socket.c b/net/socket.c
> index f85ef7d..18af2ab 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -320,11 +320,11 @@ static NetClientInfo net_dgram_socket_info = {
>  static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
>                                                  const char *model,
>                                                  const char *name,
> -                                                int fd, int is_connected)
> +                                                int fd, int is_connected,
> +                                                const char *mcast)
>  {
>      struct sockaddr_in saddr;
>      int newfd;
> -    socklen_t saddr_len = sizeof(saddr);
>      NetClientState *nc;
>      NetSocketState *s;
>  
> @@ -333,8 +333,13 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
>       * by ONLY ONE process: we must "clone" this dgram socket --jjo
>       */
>  
> -    if (is_connected) {
> -        if (getsockname(fd, (struct sockaddr *) &saddr, &saddr_len) == 0) {
> +    if (is_connected && mcast != NULL) {
> +            if (parse_host_port(&saddr, mcast) < 0) {
> +                fprintf(stderr,
> +                        "qemu: error: init_dgram: fd=%d failed parse_host_port()\n",
> +                        fd);
> +                goto err;
> +            }
>              /* must be bound */
>              if (saddr.sin_addr.s_addr == 0) {
>                  fprintf(stderr, "qemu: error: init_dgram: fd=%d unbound, "
> @@ -351,12 +356,6 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
>              dup2(newfd, fd);
>              close(newfd);
>  
> -        } else {
> -            fprintf(stderr,
> -                    "qemu: error: init_dgram: fd=%d failed getsockname(): %s\n",
> -                    fd, strerror(errno));
> -            goto err;
> -        }
>      }
>  
>      nc = qemu_new_net_client(&net_dgram_socket_info, peer, model, name);
> @@ -432,7 +431,7 @@ static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
>  
>  static NetSocketState *net_socket_fd_init(NetClientState *peer,
>                                            const char *model, const char *name,
> -                                          int fd, int is_connected)
> +                                          int fd, int is_connected, const char *mc)
>  {
>      int so_type = -1, optlen=sizeof(so_type);
>  
> @@ -445,7 +444,7 @@ static NetSocketState *net_socket_fd_init(NetClientState *peer,
>      }
>      switch(so_type) {
>      case SOCK_DGRAM:
> -        return net_socket_fd_init_dgram(peer, model, name, fd, is_connected);
> +        return net_socket_fd_init_dgram(peer, model, name, fd, is_connected, mc);
>      case SOCK_STREAM:
>          return net_socket_fd_init_stream(peer, model, name, fd, is_connected);
>      default:
> @@ -567,7 +566,7 @@ static int net_socket_connect_init(NetClientState *peer,
>              break;
>          }
>      }
> -    s = net_socket_fd_init(peer, model, name, fd, connected);
> +    s = net_socket_fd_init(peer, model, name, fd, connected, NULL);
>      if (!s)
>          return -1;
>      snprintf(s->nc.info_str, sizeof(s->nc.info_str),
> @@ -602,7 +601,7 @@ static int net_socket_mcast_init(NetClientState *peer,
>      if (fd < 0)
>          return -1;
>  
> -    s = net_socket_fd_init(peer, model, name, fd, 0);
> +    s = net_socket_fd_init(peer, model, name, fd, 0, NULL);
>      if (!s)
>          return -1;
>  
> @@ -652,7 +651,7 @@ static int net_socket_udp_init(NetClientState *peer,
>      }
>      qemu_set_nonblock(fd);
>  
> -    s = net_socket_fd_init(peer, model, name, fd, 0);
> +    s = net_socket_fd_init(peer, model, name, fd, 0, NULL);
>      if (!s) {
>          return -1;
>      }
> @@ -675,9 +674,9 @@ int net_init_socket(const Netdev *netdev, const char *name,
>      assert(netdev->type == NET_CLIENT_DRIVER_SOCKET);
>      sock = &netdev->u.socket;
>  
> -    if (sock->has_fd + sock->has_listen + sock->has_connect + sock->has_mcast +
> -        sock->has_udp != 1) {
> -        error_report("exactly one of fd=, listen=, connect=, mcast= or udp="
> +    if (sock->has_listen + sock->has_connect + sock->has_mcast +
> +        sock->has_udp > 1) {
> +        error_report("exactly one of listen=, connect=, mcast= or udp="
>                       " is required");
>          return -1;
>      }
> @@ -696,7 +695,7 @@ int net_init_socket(const Netdev *netdev, const char *name,
>              return -1;
>          }
>          qemu_set_nonblock(fd);
> -        if (!net_socket_fd_init(peer, "socket", name, fd, 1)) {
> +        if (!net_socket_fd_init(peer, "socket", name, fd, 1, sock->mcast)) {
>              return -1;
>          }
>          return 0;
> -- 
> 2.9.4