llmnrd: merge rtnl interface event loop into main select() loops

Instead of spawming a thread for the sole purpose of watching the rtnl
for (presumably) seldom events, just merge the select() for all sockets
together in one single main loop.

This reduces unnecessary complexity and makes llmnrd no longer require
any locking.

It also allows us to handle signals in a thread-safe manner (as there
aren't any ;) and thus the race condition on exit reported in #20

Closes #20
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 18 insertions, 76 deletions

diff --git a/iface.c b/iface.c
index 333a142..83dc377 100644
--- a/iface.c
+++ b/iface.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2016 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2015-2017 Tobias Klauser <tklauser@distanz.ch>
  *
  * This file is part of llmnrd.
  *
@@ -19,7 +19,6 @@
 #include <assert.h>
 #include <errno.h>
 #include <netdb.h>
-#include <pthread.h>
 #include <stdint.h>
 #include <string.h>
 #include <unistd.h>
@@ -40,10 +39,7 @@
 
 #include "iface.h"
 
-static bool iface_running = true;
-static bool iface_ipv6 = false;
 static unsigned int iface_ifindex = 0;
-static pthread_t iface_thread;
 static iface_event_handler_t iface_event_handler;
 
 struct iface_record {
@@ -54,7 +50,6 @@ struct iface_record {
 };
 
 static struct list_head iface_list_head;
-static pthread_mutex_t iface_list_mutex;
 
 size_t iface_addr_lookup(unsigned int ifindex, unsigned char family,
 			 struct sockaddr_storage *addrs, size_t addrs_size)
@@ -65,8 +60,6 @@ size_t iface_addr_lookup(unsigned int ifindex, unsigned char family,
 	if (!addrs)
 		return 0;
 
-	pthread_mutex_lock(&iface_list_mutex);
-
 	list_for_each_entry(rec, &iface_list_head, list) {
 		if (rec->index == ifindex) {
 			size_t i;
@@ -81,8 +74,6 @@ size_t iface_addr_lookup(unsigned int ifindex, unsigned char family,
 		}
 	}
 
-	pthread_mutex_unlock(&iface_list_mutex);
-
 	return n;
 }
 
@@ -182,8 +173,6 @@ static void iface_addr_add(unsigned int index, unsigned char family, const void
 
 	fill_sockaddr_storage(&sst, family, addr);
 
-	pthread_mutex_lock(&iface_list_mutex);
-
 	list_for_each_entry(rec, &iface_list_head, list)
 		if (rec->index == index)
 			goto add;
@@ -195,7 +184,6 @@ static void iface_addr_add(unsigned int index, unsigned char family, const void
 	list_add_tail(&rec->list, &iface_list_head);
 add:
 	iface_record_addr_add(rec, &sst);
-	pthread_mutex_unlock(&iface_list_mutex);
 }
 
 static void iface_addr_del(unsigned int index, unsigned char family, const void *addr)
@@ -205,16 +193,12 @@ static void iface_addr_del(unsigned int index, unsigned char family, const void
 
 	fill_sockaddr_storage(&sst, family, addr);
 
-	pthread_mutex_lock(&iface_list_mutex);
-
 	list_for_each_entry(rec, &iface_list_head, list) {
 		if (rec->index == index) {
 			iface_record_addr_del(rec, &sst);
 			break;
 		}
 	}
-
-	pthread_mutex_unlock(&iface_list_mutex);
 }
 
 static void iface_nlmsg_change_link(const struct nlmsghdr *nlh __unused)
@@ -342,75 +326,33 @@ static int iface_rtnl_enumerate(int sock, uint16_t type, unsigned char family)
 	return iface_nlmsg_process((const struct nlmsghdr *)pktbuf, recvlen);
 }
 
-void iface_register_event_handler(iface_event_handler_t event_handler)
+void iface_init(int sock, const char *iface, bool ipv6,
+		iface_event_handler_t event_handler)
 {
-	iface_event_handler = event_handler;
-}
-
-int iface_run(void)
-{
-	int ret = -1;
-	int sock;
-
 	INIT_LIST_HEAD(&iface_list_head);
-	if (pthread_mutex_init(&iface_list_mutex, NULL) != 0) {
-		log_err("Failed to initialize interface list mutex\n");
-		return -1;
-	}
-
-	sock = socket_open_rtnl(iface_ipv6);
-	if (sock < 0)
-		return -1;
+	iface_event_handler = event_handler;
+	if (iface)
+		iface_ifindex = if_nametoindex(iface);
 
 	/* send RTM_GETADDR request to initially populate the interface list */
 	if (iface_rtnl_enumerate(sock, RTM_GETADDR, AF_INET) < 0)
-		goto out;
-	if (iface_ipv6) {
+		log_err("Failed to enumerate rtnl interfaces: %s\n", strerror(errno));
+	if (ipv6)
 		if (iface_rtnl_enumerate(sock, RTM_GETADDR, AF_INET6) < 0)
-			goto out;
-	}
-
-	while (iface_running) {
-		ssize_t recvlen;
-		uint8_t pktbuf[8192];
-
-		if ((recvlen = recv(sock, pktbuf, sizeof(pktbuf), 0)) < 0) {
-			if (errno != EINTR)
-				log_err("Failed to receive netlink message: %s\n", strerror(errno));
-			goto out;
-		}
-
-		if (iface_nlmsg_process((const struct nlmsghdr *)pktbuf, recvlen) < 0)
-			log_warn("Error processing netlink message\n");
-	}
-
-	pthread_mutex_destroy(&iface_list_mutex);
-	ret = 0;
-out:
-	close(sock);
-	return ret;
-}
-
-static void* iface_run_wrapper(void *data __unused)
-{
-	return ERR_PTR(iface_run());
+			log_err("Failed to enumerate rtnl interfaces: %s\n", strerror(errno));
 }
 
-int iface_start_thread(bool ipv6, const char *iface)
+void iface_recv(int sock)
 {
-	iface_ipv6 = ipv6;
-	if (iface)
-		iface_ifindex = if_nametoindex(iface);
+	ssize_t recvlen;
+	uint8_t pktbuf[8192];
 
-	if (pthread_create(&iface_thread, NULL, iface_run_wrapper, NULL) < 0) {
-		log_err("Failed to start interface monitoring thread\n");
-		return -1;
+	if ((recvlen = recv(sock, pktbuf, sizeof(pktbuf), 0)) < 0) {
+		if (errno != EINTR)
+			log_err("Failed to receive netlink message: %s\n", strerror(errno));
+		return;
 	}
 
-	return 0;
-}
-
-void iface_stop(void)
-{
-	iface_running = false;
+	if (iface_nlmsg_process((const struct nlmsghdr *)pktbuf, recvlen) < 0)
+		log_warn("Error processing netlink message\n");
 }