src/network/netlink.c

   1 #include <errno.h>
   2 #include <string.h>
   3 #include <syscall.h>
   4 #include <sys/socket.h>
   5 #include "netlink.h"
   6
   7 static int __netlink_enumerate(int fd, unsigned int seq, int type, int af,
   8         int (*cb)(void *ctx, struct nlmsghdr *h), void *ctx)
   9 {
  10         struct nlmsghdr *h;
  11         union {
  12                 uint8_t buf[8192];
  13                 struct {
  14                         struct nlmsghdr nlh;
  15                         struct rtgenmsg g;
  16                 } req;
  17                 struct nlmsghdr reply;
  18         } u;
  19         int r, ret;
  20
  21         memset(&u.req, 0, sizeof(u.req));
  22         u.req.nlh.nlmsg_len = sizeof(u.req);
  23         u.req.nlh.nlmsg_type = type;
  24         u.req.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
  25         u.req.nlh.nlmsg_seq = seq;
  26         u.req.g.rtgen_family = af;
  27         r = send(fd, &u.req, sizeof(u.req), 0);
  28         if (r < 0) return r;
  29
  30         while (1) {
  31                 r = recv(fd, u.buf, sizeof(u.buf), MSG_DONTWAIT);
  32                 if (r <= 0) return -1;
  33                 for (h = &u.reply; NLMSG_OK(h, (void*)&u.buf[r]); h = NLMSG_NEXT(h)) {
  34                         if (h->nlmsg_type == NLMSG_DONE) return 0;
  35                         if (h->nlmsg_type == NLMSG_ERROR) return -1;
  36                         ret = cb(ctx, h);
  37                         if (ret) return ret;
  38                 }
  39         }
  40 }
  41
  42 int __rtnetlink_enumerate(int link_af, int addr_af, int (*cb)(void *ctx, struct nlmsghdr *h), void *ctx)
  43 {
  44         int fd, r;
  45
  46         fd = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE);
  47         if (fd < 0) return -1;
  48         r = __netlink_enumerate(fd, 1, RTM_GETLINK, link_af, cb, ctx);
  49         if (!r) r = __netlink_enumerate(fd, 2, RTM_GETADDR, addr_af, cb, ctx);
  50         __syscall(SYS_close,fd);
  51         return r;
  52 }