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dnsmasq: fix a race condition possibly leading to lockup
SVN-Revision: 42225
This commit is contained in:
Steven Barth
parent
f66a0912f7
commit
0f49b1940e
@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
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PKG_NAME:=dnsmasq
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PKG_VERSION:=2.71
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PKG_RELEASE:=3
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PKG_RELEASE:=4
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PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
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PKG_SOURCE_URL:=http://thekelleys.org.uk/dnsmasq
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@ -0,0 +1,277 @@
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From a0358e5ddbc1ef3dec791f11f95f5dbe56087a5e Mon Sep 17 00:00:00 2001
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From: Simon Kelley <simon@thekelleys.org.uk>
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Date: Sat, 7 Jun 2014 13:38:48 +0100
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Subject: [PATCH] Handle async notification of address changes using the event
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system.
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---
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CHANGELOG | 4 ++++
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src/bpf.c | 6 +++---
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src/dhcp6.c | 10 ----------
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src/dnsmasq.c | 13 +++++++++++--
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src/dnsmasq.h | 6 ++++--
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src/netlink.c | 39 ++++++++++-----------------------------
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src/network.c | 11 +++--------
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7 files changed, 35 insertions(+), 54 deletions(-)
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--- a/CHANGELOG
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+++ b/CHANGELOG
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@@ -15,6 +15,10 @@ version 2.71
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regression introduced in 2.69. Thanks to James Hunt and
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the Ubuntu crowd for assistance in fixing this.
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+ Fix race condition which could lock up dnsmasq when an
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+ interface goes down and up rapidly. Thanks to Conrad
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+ Kostecki for helping to chase this down.
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+
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version 2.70
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Fix crash, introduced in 2.69, on TCP request when dnsmasq
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--- a/src/bpf.c
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+++ b/src/bpf.c
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@@ -376,7 +376,7 @@ void route_init(void)
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die(_("cannot create PF_ROUTE socket: %s"), NULL, EC_BADNET);
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}
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-void route_sock(time_t now)
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+void route_sock(void)
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{
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struct if_msghdr *msg;
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int rc = recv(daemon->routefd, daemon->packet, daemon->packet_buff_sz, 0);
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@@ -401,7 +401,7 @@ void route_sock(time_t now)
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else if (msg->ifm_type == RTM_NEWADDR)
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{
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del_family = 0;
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- newaddress(now);
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+ send_newaddr();
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}
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else if (msg->ifm_type == RTM_DELADDR)
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{
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@@ -439,7 +439,7 @@ void route_sock(time_t now)
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of += sizeof(long) - (diff & (sizeof(long) - 1));
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}
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- newaddress(now);
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+ send_newaddr();
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}
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}
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--- a/src/dnsmasq.c
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+++ b/src/dnsmasq.c
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@@ -917,10 +917,10 @@ int main (int argc, char **argv)
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#if defined(HAVE_LINUX_NETWORK)
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if (FD_ISSET(daemon->netlinkfd, &rset))
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- netlink_multicast(now);
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+ netlink_multicast();
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#elif defined(HAVE_BSD_NETWORK)
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if (FD_ISSET(daemon->routefd, &rset))
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- route_sock(now);
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+ route_sock();
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#endif
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/* Check for changes to resolv files once per second max. */
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@@ -1037,6 +1037,11 @@ void send_alarm(time_t event, time_t now
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}
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}
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+void send_newaddr(void)
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+{
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+ send_event(pipewrite, EVENT_NEWADDR, 0, NULL);
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+}
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+
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void send_event(int fd, int event, int data, char *msg)
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{
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struct event_desc ev;
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@@ -1230,6 +1235,10 @@ static void async_event(int pipe, time_t
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if (daemon->log_file != NULL)
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log_reopen(daemon->log_file);
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break;
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+
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+ case EVENT_NEWADDR:
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+ newaddress(now);
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+ break;
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case EVENT_TERM:
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/* Knock all our children on the head. */
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--- a/src/dnsmasq.h
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+++ b/src/dnsmasq.h
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@@ -165,6 +165,7 @@ struct event_desc {
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#define EVENT_LUA_ERR 19
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#define EVENT_TFTP_ERR 20
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#define EVENT_INIT 21
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+#define EVENT_NEWADDR 22
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/* Exit codes. */
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#define EC_GOOD 0
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@@ -1289,6 +1290,7 @@ unsigned char *extended_hwaddr(int hwtyp
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int make_icmp_sock(void);
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int icmp_ping(struct in_addr addr);
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#endif
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+void send_newaddr(void);
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void send_alarm(time_t event, time_t now);
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void send_event(int fd, int event, int data, char *msg);
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void clear_cache_and_reload(time_t now);
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@@ -1297,7 +1299,7 @@ void poll_resolv(int force, int do_reloa
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/* netlink.c */
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#ifdef HAVE_LINUX_NETWORK
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void netlink_init(void);
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-void netlink_multicast(time_t now);
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+void netlink_multicast(void);
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#endif
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/* bpf.c */
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@@ -1306,7 +1308,7 @@ void init_bpf(void);
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void send_via_bpf(struct dhcp_packet *mess, size_t len,
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struct in_addr iface_addr, struct ifreq *ifr);
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void route_init(void);
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-void route_sock(time_t now);
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+void route_sock(void);
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#endif
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/* bpf.c or netlink.c */
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--- a/src/netlink.c
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+++ b/src/netlink.c
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@@ -38,7 +38,7 @@
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static struct iovec iov;
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static u32 netlink_pid;
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-static int nl_async(struct nlmsghdr *h);
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+static void nl_async(struct nlmsghdr *h);
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void netlink_init(void)
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{
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@@ -142,7 +142,7 @@ int iface_enumerate(int family, void *pa
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struct nlmsghdr *h;
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ssize_t len;
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static unsigned int seq = 0;
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- int callback_ok = 1, newaddr = 0;
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+ int callback_ok = 1;
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struct {
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struct nlmsghdr nlh;
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@@ -191,21 +191,10 @@ int iface_enumerate(int family, void *pa
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if (h->nlmsg_seq != seq || h->nlmsg_pid != netlink_pid || h->nlmsg_type == NLMSG_ERROR)
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{
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/* May be multicast arriving async */
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- if (nl_async(h))
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- {
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- newaddr = 1;
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- enumerate_interfaces(1); /* reset */
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- }
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+ nl_async(h);
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}
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else if (h->nlmsg_type == NLMSG_DONE)
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- {
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- /* handle async new interface address arrivals, these have to be done
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- after we complete as we're not re-entrant */
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- if (newaddr)
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- newaddress(dnsmasq_time());
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-
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- return callback_ok;
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- }
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+ return callback_ok;
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else if (h->nlmsg_type == RTM_NEWADDR && family != AF_UNSPEC && family != AF_LOCAL)
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{
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struct ifaddrmsg *ifa = NLMSG_DATA(h);
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@@ -330,11 +319,11 @@ int iface_enumerate(int family, void *pa
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}
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}
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-void netlink_multicast(time_t now)
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+void netlink_multicast(void)
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{
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ssize_t len;
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struct nlmsghdr *h;
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- int flags, newaddr = 0;
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+ int flags;
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/* don't risk blocking reading netlink messages here. */
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if ((flags = fcntl(daemon->netlinkfd, F_GETFL)) == -1 ||
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@@ -343,24 +332,19 @@ void netlink_multicast(time_t now)
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if ((len = netlink_recv()) != -1)
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for (h = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(h, (size_t)len); h = NLMSG_NEXT(h, len))
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- if (nl_async(h))
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- newaddr = 1;
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+ nl_async(h);
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/* restore non-blocking status */
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fcntl(daemon->netlinkfd, F_SETFL, flags);
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-
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- if (newaddr)
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- newaddress(now);
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}
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-static int nl_async(struct nlmsghdr *h)
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+static void nl_async(struct nlmsghdr *h)
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{
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if (h->nlmsg_type == NLMSG_ERROR)
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{
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struct nlmsgerr *err = NLMSG_DATA(h);
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if (err->error != 0)
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my_syslog(LOG_ERR, _("netlink returns error: %s"), strerror(-(err->error)));
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- return 0;
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}
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else if (h->nlmsg_pid == 0 && h->nlmsg_type == RTM_NEWROUTE)
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{
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@@ -385,18 +369,15 @@ static int nl_async(struct nlmsghdr *h)
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else if (daemon->rfd_save && daemon->rfd_save->refcount != 0)
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fd = daemon->rfd_save->fd;
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else
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- return 0;
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+ return;
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while(sendto(fd, daemon->packet, daemon->packet_len, 0,
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&daemon->srv_save->addr.sa, sa_len(&daemon->srv_save->addr)) == -1 && retry_send());
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}
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}
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- return 0;
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}
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else if (h->nlmsg_type == RTM_NEWADDR || h->nlmsg_type == RTM_DELADDR)
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- return 1; /* clever bind mode - rescan */
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-
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- return 0;
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+ send_newaddr();
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}
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#endif
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--- a/src/network.c
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+++ b/src/network.c
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@@ -551,7 +551,7 @@ static int iface_allowed_v4(struct in_ad
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int enumerate_interfaces(int reset)
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{
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static struct addrlist *spare = NULL;
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- static int done = 0, active = 0;
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+ static int done = 0;
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struct iface_param param;
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int errsave, ret = 1;
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struct addrlist *addr, *tmp;
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@@ -570,14 +570,11 @@ int enumerate_interfaces(int reset)
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return 1;
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}
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- if (done || active)
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+ if (done)
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return 1;
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done = 1;
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- /* protect against recusive calls from iface_enumerate(); */
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- active = 1;
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-
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if ((param.fd = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
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return 0;
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@@ -677,10 +674,8 @@ int enumerate_interfaces(int reset)
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}
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errno = errsave;
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-
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spare = param.spare;
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- active = 0;
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-
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+
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return ret;
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}
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