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/* ISC license. */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <string.h>
#include <errno.h>
#include <net/if.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <bcnm/if.h>
static inline ssize_t fd_recvmsg_nb (int fd, struct msghdr *hdr)
{
int e = errno ;
ssize_t r ;
do r = recvmsg(fd, hdr, MSG_DONTWAIT) ;
while (r == -1 && errno == EINTR) ;
if (r == -1 && errno == EWOULDBLOCK) return (errno = e, 0) ;
if (!r) return (errno = EPIPE, -1) ;
return r ;
}
static int answer (bcnm_if_link_state_t *tab, size_t n, char const *ifname, unsigned int state)
{
size_t i = 0 ;
for (; i < n ; i++) if (!strcmp(ifname, tab[i].ifname)) break ;
if (i >= n) return 0 ;
tab[i].state = state ;
tab[i].changed = 1 ;
return 1 ;
}
ssize_t bcnm_if_link_event (int fd, bcnm_if_link_state_t *tab, size_t n)
{
ssize_t e = 0 ;
struct sockaddr_nl nl ;
struct nlmsghdr buf[8192 / sizeof(struct nlmsghdr)] ;
struct iovec v = { .iov_base = buf, .iov_len = sizeof(struct nlmsghdr) * (8192 / sizeof(struct nlmsghdr)) } ;
struct msghdr msg =
{
.msg_name = &nl,
.msg_namelen = sizeof(struct sockaddr_nl),
.msg_iov = &v,
.msg_iovlen = 1,
.msg_control = 0,
.msg_controllen = 0,
.msg_flags = 0
} ;
ssize_t r = fd_recvmsg_nb(fd, &msg) ;
if (r <= 0) return r ;
if (msg.msg_flags & MSG_TRUNC) return (errno = ENOBUFS, -1) ;
if (nl.nl_pid) return (errno = EPROTO, -1) ;
for (struct nlmsghdr *hdr = buf ; NLMSG_OK(hdr, r) ; hdr = NLMSG_NEXT(hdr, r))
{
struct ifinfomsg *ifi = NLMSG_DATA(hdr) ;
char ifname[IF_NAMESIZE] ;
switch (hdr->nlmsg_type)
{
case NLMSG_DONE : goto out ;
case NLMSG_ERROR : return (errno = EPROTO, -1) ;
case RTM_DELLINK :
if_indextoname(ifi->ifi_index, ifname) ;
e += answer(tab, n, ifname, 0) ;
break ;
case RTM_NEWLINK :
if_indextoname(ifi->ifi_index, ifname) ;
e += answer(tab, n, ifname, 1 | !!(ifi->ifi_flags & IFF_UP) << 1 | !!(ifi->ifi_flags & IFF_RUNNING) << 2) ;
break ;
}
}
out:
return e ;
}
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