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Convert failure of setsockopt(..., SOL_NETLINK, NETLINK_NO_ENOBUFS, ...) into warning.

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We call this, which avoids POLLERR returns from netlink on a loaded system,
if the kernel is new enough to support it. Sadly, qemu-user doesn't support
the socket option, so if it fails despite the kernel being new enough to
support it, we just emit a warning, rather than failing hard.
This commit is contained in:
Simon Kelley
2020-04-19 23:16:52 +01:00
parent 00fe2f49e0
commit 913fa15fb1
3 changed files with 14 additions and 5 deletions
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6
src/dnsmasq.c
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@@ -58,6 +58,7 @@ int main (int argc, char **argv)
char *bound_device = NULL; char *bound_device = NULL;
int did_bind = 0; int did_bind = 0;
struct server *serv; struct server *serv;
char *netlink_warn;
#endif #endif
#if defined(HAVE_DHCP) || defined(HAVE_DHCP6) #if defined(HAVE_DHCP) || defined(HAVE_DHCP6)
struct dhcp_context *context; struct dhcp_context *context;
@@ -327,7 +328,7 @@ int main (int argc, char **argv)
#endif #endif
#if defined(HAVE_LINUX_NETWORK) #if defined(HAVE_LINUX_NETWORK)
netlink_init(); netlink_warn = netlink_init();
#elif defined(HAVE_BSD_NETWORK) #elif defined(HAVE_BSD_NETWORK)
route_init(); route_init();
#endif #endif
@@ -946,6 +947,9 @@ int main (int argc, char **argv)
# ifdef HAVE_LINUX_NETWORK # ifdef HAVE_LINUX_NETWORK
if (did_bind) if (did_bind)
my_syslog(MS_DHCP | LOG_INFO, _("DHCP, sockets bound exclusively to interface %s"), bound_device); my_syslog(MS_DHCP | LOG_INFO, _("DHCP, sockets bound exclusively to interface %s"), bound_device);
if (netlink_warn)
my_syslog(LOG_WARNING, netlink_warn);
# endif # endif
/* after dhcp_construct_contexts */ /* after dhcp_construct_contexts */

2
src/dnsmasq.h
View File

@@ -1450,7 +1450,7 @@ void clear_cache_and_reload(time_t now);
/* netlink.c */ /* netlink.c */
#ifdef HAVE_LINUX_NETWORK #ifdef HAVE_LINUX_NETWORK
void netlink_init(void); char *netlink_init(void);
void netlink_multicast(void); void netlink_multicast(void);
#endif #endif

11
src/netlink.c
View File

@@ -49,7 +49,7 @@ static u32 netlink_pid;
static void nl_async(struct nlmsghdr *h); static void nl_async(struct nlmsghdr *h);
void netlink_init(void) char *netlink_init(void)
{ {
struct sockaddr_nl addr; struct sockaddr_nl addr;
socklen_t slen = sizeof(addr); socklen_t slen = sizeof(addr);
@@ -82,16 +82,21 @@ void netlink_init(void)
} }
if (daemon->netlinkfd == -1 || if (daemon->netlinkfd == -1 ||
(daemon->kernel_version >= KERNEL_VERSION(2,6,30) &&
setsockopt(daemon->netlinkfd, SOL_NETLINK, NETLINK_NO_ENOBUFS, &opt, sizeof(opt)) == -1) ||
getsockname(daemon->netlinkfd, (struct sockaddr *)&addr, &slen) == -1) getsockname(daemon->netlinkfd, (struct sockaddr *)&addr, &slen) == -1)
die(_("cannot create netlink socket: %s"), NULL, EC_MISC); die(_("cannot create netlink socket: %s"), NULL, EC_MISC);
/* save pid assigned by bind() and retrieved by getsockname() */ /* save pid assigned by bind() and retrieved by getsockname() */
netlink_pid = addr.nl_pid; netlink_pid = addr.nl_pid;
iov.iov_len = 100; iov.iov_len = 100;
iov.iov_base = safe_malloc(iov.iov_len); iov.iov_base = safe_malloc(iov.iov_len);
if (daemon->kernel_version >= KERNEL_VERSION(2,6,30) &&
setsockopt(daemon->netlinkfd, SOL_NETLINK, NETLINK_NO_ENOBUFS, &opt, sizeof(opt)) == -1)
return _("warning: failed to set NETLINK_NO_ENOBUFS on netlink socket");
return NULL;
} }
static ssize_t netlink_recv(void) static ssize_t netlink_recv(void)