text: #include <errno.h>
  #include <string.h>
  #include <syscall.h>
  #include <sys/socket.h>
  #include "netlink.h"
  
  static int __netlink_enumerate(int fd, unsigned int seq, int type, int af,
  	int (*cb)(void *ctx, struct nlmsghdr *h), void *ctx)
  {
  	struct nlmsghdr *h;
  	union {
  		uint8_t buf[8192];
  		struct {
  			struct nlmsghdr nlh;
  			struct rtgenmsg g;
  		} req;
  		struct nlmsghdr reply;
  	} u;
  	int r, ret;
  
  	memset(&u.req, 0, sizeof(u.req));
  	u.req.nlh.nlmsg_len = sizeof(u.req);
  	u.req.nlh.nlmsg_type = type;
  	u.req.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
  	u.req.nlh.nlmsg_seq = seq;
  	u.req.g.rtgen_family = af;
  	r = send(fd, &u.req, sizeof(u.req), 0);
  	if (r < 0) return r;
  
  	while (1) {
  		r = recv(fd, u.buf, sizeof(u.buf), MSG_DONTWAIT);
  		if (r <= 0) return -1;
  		for (h = &u.reply; NLMSG_OK(h, (void*)&u.buf[r]); h = NLMSG_NEXT(h)) {
  			if (h->nlmsg_type == NLMSG_DONE) return 0;
  			if (h->nlmsg_type == NLMSG_ERROR) return -1;
  			ret = cb(ctx, h);
  			if (ret) return ret;
  		}
  	}
  }
  
  int __rtnetlink_enumerate(int link_af, int addr_af, int (*cb)(void *ctx, struct nlmsghdr *h), void *ctx)
  {
  	int fd, r;
  
  	fd = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE);
  	if (fd < 0) return -1;
  	r = __netlink_enumerate(fd, 1, RTM_GETLINK, link_af, cb, ctx);
  	if (!r) r = __netlink_enumerate(fd, 2, RTM_GETADDR, addr_af, cb, ctx);
  	__async_syscall(SYS_close,fd);
  	return r;
  }
  