Re: [PATCH v9 11/16] net: dgram: add unix socket

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Sep 26, 2022 at 09:50:43PM +0200, Laurent Vivier wrote:
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> Reviewed-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Although one note below.

> ---
>  net/dgram.c     | 65 ++++++++++++++++++++++++++++++++++++++++++++++---
>  qapi/net.json   |  2 +-
>  qemu-options.hx |  1 +
>  3 files changed, 64 insertions(+), 4 deletions(-)
> 
> diff --git a/net/dgram.c b/net/dgram.c
> index 9fb01410304e..db631f6e2270 100644
> --- a/net/dgram.c
> +++ b/net/dgram.c
> @@ -84,8 +84,15 @@ static ssize_t net_dgram_receive_dgram(NetClientState *nc,
>  
>      do {
>          if (s->dgram_dst) {
> -            ret = sendto(s->fd, buf, size, 0, s->dgram_dst,
> -                         sizeof(struct sockaddr_in));
> +            socklen_t len;
> +
> +            if (s->dgram_dst->sa_family == AF_INET) {
> +                len = sizeof(struct sockaddr_in);
> +            } else {
> +                len = sizeof(struct sockaddr_un);
> +            }

It really seems like you're going to want a common helper for getting
the socklet, if not now, then pretty soon.

> +            ret = sendto(s->fd, buf, size, 0, s->dgram_dst, len);
>          } else {
>              ret = send(s->fd, buf, size, 0);
>          }
> @@ -450,7 +457,7 @@ static int net_dgram_init(NetClientState *peer,
>          }
>      } else {
>          if (local->type != SOCKET_ADDRESS_TYPE_FD) {
> -            error_setg(errp, "type=inet requires remote parameter");
> +            error_setg(errp, "type=inet or unix require remote parameter");
>              return -1;
>          }
>      }
> @@ -500,6 +507,58 @@ static int net_dgram_init(NetClientState *peer,
>  
>          break;
>      }
> +    case SOCKET_ADDRESS_TYPE_UNIX: {
> +        struct sockaddr_un laddr_un, raddr_un;
> +
> +        ret = unlink(local->u.q_unix.path);
> +        if (ret < 0 && errno != ENOENT) {
> +            error_setg_errno(errp, errno, "failed to unlink socket %s",
> +                             local->u.q_unix.path);
> +            return -1;
> +        }
> +
> +        laddr_un.sun_family = PF_UNIX;
> +        ret = snprintf(laddr_un.sun_path, sizeof(laddr_un.sun_path), "%s",
> +                       local->u.q_unix.path);
> +        if (ret < 0 || ret >= sizeof(laddr_un.sun_path)) {
> +            error_setg(errp, "UNIX socket path '%s' is too long",
> +                       local->u.q_unix.path);
> +            error_append_hint(errp, "Path must be less than %zu bytes\n",
> +                              sizeof(laddr_un.sun_path));
> +        }
> +
> +        raddr_un.sun_family = PF_UNIX;
> +        ret = snprintf(raddr_un.sun_path, sizeof(raddr_un.sun_path), "%s",
> +                       remote->u.q_unix.path);
> +        if (ret < 0 || ret >= sizeof(raddr_un.sun_path)) {
> +            error_setg(errp, "UNIX socket path '%s' is too long",
> +                       remote->u.q_unix.path);
> +            error_append_hint(errp, "Path must be less than %zu bytes\n",
> +                              sizeof(raddr_un.sun_path));
> +        }
> +
> +        fd = qemu_socket(PF_UNIX, SOCK_DGRAM, 0);
> +        if (fd < 0) {
> +            error_setg_errno(errp, errno, "can't create datagram socket");
> +            return -1;
> +        }
> +
> +        ret = bind(fd, (struct sockaddr *)&laddr_un, sizeof(laddr_un));
> +        if (ret < 0) {
> +            error_setg_errno(errp, errno, "can't bind unix=%s to socket",
> +                             laddr_un.sun_path);
> +            closesocket(fd);
> +            return -1;
> +        }
> +        qemu_socket_set_nonblock(fd);
> +
> +        dgram_dst = g_malloc(sizeof(raddr_un));
> +        memcpy(dgram_dst, &raddr_un, sizeof(raddr_un));
> +
> +        info_str = g_strdup_printf("udp=%s:%s",
> +                                   laddr_un.sun_path, raddr_un.sun_path);
> +        break;
> +    }
>      case SOCKET_ADDRESS_TYPE_FD: {
>          SocketAddress *sa;
>          SocketAddressType sa_type;
> diff --git a/qapi/net.json b/qapi/net.json
> index bb96701a49a7..9cc4be7535bb 100644
> --- a/qapi/net.json
> +++ b/qapi/net.json
> @@ -600,7 +600,7 @@
>  # @remote: remote address
>  # @local: local address
>  #
> -# Only SocketAddress types 'inet' and 'fd' are supported.
> +# Only SocketAddress types 'unix', 'inet' and 'fd' are supported.
>  #
>  # The code checks there is at least one of these options and reports an error
>  # if not. If remote address is present and it's a multicast address, local
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 7a34022ac651..5adb2e688c73 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -2744,6 +2744,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
>      "                configure a network backend to connect to a multicast maddr and port\n"
>      "                use ``local.host=addr`` to specify the host address to send packets from\n"
>      "-netdev dgram,id=str,local.type=inet,local.host=addr,local.port=port[,remote.type=inet,remote.host=addr,remote.port=port]\n"
> +    "-netdev dgram,id=str,local.type=unix,local.path=path[,remote.type=unix,remote.path=path]\n"
>      "-netdev dgram,id=str,local.type=fd,local.str=h\n"
>      "                configure a network backend to connect to another network\n"
>      "                using an UDP tunnel\n"

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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