Ask for link and address data on the same socket.

[Thomas Graf]

On 07/18/13 at 05:15pm, Tilman Baumann wrote:
> On 11/07/13 20:32, Thomas Graf wrote:
> > On 07/10/13 at 03:48pm, Tilman Baumann wrote:
> >> On 04/07/13 20:55, Thomas Graf wrote:
> >>
> >> The parse part can deal with both types of responses very well.
> >> Do you mean I should send the requests individually via send() and with
> >> NLMSG_DONE?
> >> Or assemble the request chain how I did with NLMSG_NEXT() and a empty or
> >> rtgenmsg request with NLMSG_DONE at the end?
> > The kernel is not ready to handle that.
> >
> > I suggest that you use individual send() calls to send the RTM_GETADDR
> > and RTM_GETLINK requests so you don't need to send a NLMSG_DONE
> > message at all.
> Thanks again for taking your time.
> 
> I simplified the code a bit. Too much cargo cult going on. (Still the
> case, but I think I grokk it)
> 
> I assemble two messages, one RTM_GETLINK and one RTM_GETADDR, and send
> them individually.
> But my receive function again only receives the first one.
> 
> I think I'm still missing a clue here.
> If you like I can send you my receive function.
> 
> My request function now:
> {
>         int status;
>         struct {
>               struct nlmsghdr n;
>               struct ifaddrmsg r;
>         } ifaddr_req;
> 
>         struct {
>               struct nlmsghdr n;
>               struct ifinfomsg r;
>         } ifinfo_req;
> 
>         memset(&ifaddr_req, 0, sizeof(ifaddr_req));
>         ifaddr_req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
>         ifaddr_req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
>         ifaddr_req.n.nlmsg_type = RTM_GETADDR;
> 
>         status = send(netlinkfd, &ifaddr_req, ifaddr_req.n.nlmsg_len, 0);
>         if (status < 0) {
>                 perror("[Listener] send");
>                 return 1;
>         }

You should receive the answer to the first request here.

>         memset(&ifinfo_req, 0, sizeof(ifinfo_req));
>         ifinfo_req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
                                                           ^^^^^^^^^^^^^^

>         ifinfo_req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
>         ifinfo_req.n.nlmsg_type = RTM_GETLINK;
> 
>         status = send(netlinkfd, &ifinfo_req, ifinfo_req.n.nlmsg_len, 0);
>         if (status < 0) {
>                 perror("[Listener] send");
>                 return 1;
>         }
>         return 1;
> }