[ovs-dev] netlink-socket.c: add support for do_lookup_genl_family on Windows

[Gurucharan Shetty]

On Fri, Aug 22, 2014 at 1:16 AM, Nithin Raju <nithin at vmware.com> wrote:
> In this patch, we add support for querying the genl family id for any
> family supported by the OVS kernel datapath. On platforms that support
> netlink natively, the operating system assigns a family ID, and the
> OS netlink infrastructure supports querying the family ID by name.
>
> In case of Windows, since OVS datpath provides the netlink support,
> it is not necessary to make a call into the kernel. Returning a
> family ID that is consistent between the userspace and kernel
> is sufficient. Once there is code to support netlink message parsing
> as well as constructing netlink messages, we can make a call into
> the kernel, but that in itself may not buy anything more than this
> approach.
>
> This patch is a precursor to make progress of the other commands.
> The next hurdle is to support nl_lookup_genl_mcgroup().
>
> Signed-off-by: Nithin Raju <nithin at vmware.com>
> ---
>  lib/netlink-socket.c |   68 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 68 insertions(+), 0 deletions(-)
>
> diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c
> index 3f1a712..98baf58 100644
> --- a/lib/netlink-socket.c
> +++ b/lib/netlink-socket.c
> @@ -1128,6 +1128,7 @@ genl_family_to_name(uint16_t id)
>      }
>  }
>
> +#ifndef _WIN32
>  static int
>  do_lookup_genl_family(const char *name, struct nlattr **attrs,
>                        struct ofpbuf **replyp)
> @@ -1165,6 +1166,73 @@ do_lookup_genl_family(const char *name, struct nlattr **attrs,
>      *replyp = reply;
>      return 0;
>  }
> +#else
> +static int
> +do_lookup_genl_family(const char *name, struct nlattr **attrs,
> +                      struct ofpbuf **replyp)
> +{
> +    struct nl_sock *sock;
> +    struct ofpbuf *reply;
> +    int error;
> +    uint16_t family_id;
> +    const char *family_name;
> +    uint32_t family_version;
> +    uint32_t family_attrmax;
> +
> +    *replyp = NULL;
> +    reply = ofpbuf_new(1024);
> +
> +    if (!strcmp(name, OVS_WIN_CONTROL_FAMILY)) {
> +        family_id = OVS_WIN_NL_CTRL_FAMILY_ID;
> +        family_name = OVS_WIN_CONTROL_FAMILY;
> +        family_version = OVS_WIN_CONTROL_VERSION;
> +        family_attrmax = OVS_WIN_CONTROL_ATTR_MAX;
> +    } else if (!strcmp(name, OVS_DATAPATH_FAMILY)) {
> +        family_id = OVS_WIN_NL_DATAPATH_FAMILY_ID;
> +        family_name = OVS_DATAPATH_FAMILY;
> +        family_version = OVS_DATAPATH_VERSION;
> +        family_attrmax = OVS_DP_ATTR_MAX;
> +    } else if (!strcmp(name, OVS_PACKET_FAMILY)) {
> +        family_id = OVS_WIN_NL_PACKET_FAMILY_ID;
> +        family_name = OVS_PACKET_FAMILY;
> +        family_version = OVS_PACKET_VERSION;
> +        family_attrmax = OVS_PACKET_ATTR_MAX;
> +    } else if (!strcmp(name, OVS_VPORT_FAMILY)) {
> +        family_id = OVS_WIN_NL_VPORT_FAMILY_ID;
> +        family_name = OVS_VPORT_FAMILY;
> +        family_version = OVS_VPORT_VERSION;
> +        family_attrmax = OVS_VPORT_ATTR_MAX;
> +    } else if (!strcmp(name, OVS_FLOW_FAMILY)) {
> +        family_id = OVS_WIN_NL_FLOW_FAMILY_ID;
> +        family_name = OVS_FLOW_FAMILY;
> +        family_version = OVS_FLOW_VERSION;
> +        family_attrmax = OVS_FLOW_ATTR_MAX;
> +    } else {
> +        ofpbuf_delete(reply);
> +        return EINVAL;
> +    }
> +
> +    nl_msg_put_genlmsghdr(reply, 0, GENL_ID_CTRL, 0,
> +                          CTRL_CMD_NEWFAMILY, family_version);
> +    /* CTRL_ATTR_HDRSIZE and CTRL_ATTR_OPS are not populated, but the
> +     * callers do not seem to need them. */
> +    nl_msg_put_u16(reply, CTRL_ATTR_FAMILY_ID, family_id);
> +    nl_msg_put_string(reply, CTRL_ATTR_FAMILY_NAME, family_name);
> +    nl_msg_put_u32(reply, CTRL_ATTR_VERSION, family_version);
> +    nl_msg_put_u32(reply, CTRL_ATTR_MAXATTR, family_attrmax);
> +
> +    if (!nl_policy_parse(reply, NLMSG_HDRLEN + GENL_HDRLEN,
> +                         family_policy, attrs, ARRAY_SIZE(family_policy))
> +        || nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]) == 0) {
> +        nl_sock_destroy(sock);
Gives an "uninitialized local variable 'sock' used". Can you take care
of it in an upcoming patch?
> +        ofpbuf_delete(reply);
> +        return EPROTO;
> +    }
> +
> +    *replyp = reply;
> +    return 0;
> +}
> +#endif
>
>  /* Finds the multicast group called 'group_name' in genl family 'family_name'.
>   * When successful, writes its result to 'multicast_group' and returns 0.
> --
> 1.7.4.1
>
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