genl.c

   1 /*
   2  * This ought to be provided by libnl
   3  */
   4
   5 #include <asm/errno.h>
   6 #include <netlink/genl/genl.h>
   7 #include <netlink/genl/family.h>
   8 #include <netlink/genl/ctrl.h>
   9 #include <netlink/msg.h>
  10 #include <netlink/attr.h>
  11 #include <linux/genetlink.h>
  12
  13 #include "iw.h"
  14
  15 static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err,
  16                          void *arg)
  17 {
  18         int *ret = arg;
  19         *ret = err->error;
  20         return NL_STOP;
  21 }
  22
  23 static int ack_handler(struct nl_msg *msg, void *arg)
  24 {
  25         int *ret = arg;
  26         *ret = 0;
  27         return NL_STOP;
  28 }
  29
  30 struct handler_args {
  31         const char *group;
  32         int id;
  33 };
  34
  35 static int family_handler(struct nl_msg *msg, void *arg)
  36 {
  37         struct handler_args *grp = arg;
  38         struct nlattr *tb[CTRL_ATTR_MAX + 1];
  39         struct genlmsghdr *gnlh = nlmsg_data(nlmsg_hdr(msg));
  40         struct nlattr *mcgrp;
  41         int rem_mcgrp;
  42
  43         nla_parse(tb, CTRL_ATTR_MAX, genlmsg_attrdata(gnlh, 0),
  44                   genlmsg_attrlen(gnlh, 0), NULL);
  45
  46         if (!tb[CTRL_ATTR_MCAST_GROUPS])
  47                 return NL_SKIP;
  48
  49         nla_for_each_nested(mcgrp, tb[CTRL_ATTR_MCAST_GROUPS], rem_mcgrp) {
  50                 struct nlattr *tb_mcgrp[CTRL_ATTR_MCAST_GRP_MAX + 1];
  51
  52                 nla_parse(tb_mcgrp, CTRL_ATTR_MCAST_GRP_MAX,
  53                           nla_data(mcgrp), nla_len(mcgrp), NULL);
  54
  55                 if (!tb_mcgrp[CTRL_ATTR_MCAST_GRP_NAME] ||
  56                     !tb_mcgrp[CTRL_ATTR_MCAST_GRP_ID])
  57                         continue;
  58                 if (strncmp(nla_data(tb_mcgrp[CTRL_ATTR_MCAST_GRP_NAME]),
  59                             grp->group, nla_len(tb_mcgrp[CTRL_ATTR_MCAST_GRP_NAME])))
  60                         continue;
  61                 grp->id = nla_get_u32(tb_mcgrp[CTRL_ATTR_MCAST_GRP_ID]);
  62                 break;
  63         }
  64
  65         return NL_SKIP;
  66 }
  67
  68 int nl_get_multicast_id(struct nl_sock *sock, const char *family, const char *group)
  69 {
  70         struct nl_msg *msg;
  71         struct nl_cb *cb;
  72         int ret, ctrlid;
  73         struct handler_args grp = {
  74                 .group = group,
  75                 .id = -ENOENT,
  76         };
  77
  78         msg = nlmsg_alloc();
  79         if (!msg)
  80                 return -ENOMEM;
  81
  82         cb = nl_cb_alloc(NL_CB_DEFAULT);
  83         if (!cb) {
  84                 ret = -ENOMEM;
  85                 goto out_fail_cb;
  86         }
  87
  88         ctrlid = genl_ctrl_resolve(sock, "nlctrl");
  89
  90         genlmsg_put(msg, 0, 0, ctrlid, 0,
  91                     0, CTRL_CMD_GETFAMILY, 0);
  92
  93         ret = -ENOBUFS;
  94         NLA_PUT_STRING(msg, CTRL_ATTR_FAMILY_NAME, family);
  95
  96         ret = nl_send_auto_complete(sock, msg);
  97         if (ret < 0)
  98                 goto out;
  99
 100         ret = 1;
 101
 102         nl_cb_err(cb, NL_CB_CUSTOM, error_handler, &ret);
 103         nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, ack_handler, &ret);
 104         nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, family_handler, &grp);
 105
 106         while (ret > 0)
 107                 nl_recvmsgs(sock, cb);
 108
 109         if (ret == 0)
 110                 ret = grp.id;
 111  nla_put_failure:
 112  out:
 113         nl_cb_put(cb);
 114  out_fail_cb:
 115         nlmsg_free(msg);
 116         return ret;
 117 }