Monitor a Netlink socket on Linux.

diff --git a/src/discovery.c b/src/discovery.c
index 642c7e145fe868df6f12dfc1c7c0e1548ddfd2f7..5687cc351c50488ae940c34746e63a1a41c57ceb 100644 (file)
--- a/src/discovery.c
+++ b/src/discovery.c
@@ -11,6 +11,10 @@
 
 #if defined(__APPLE__) || defined(__unix) && !defined(__linux)
 #include <net/route.h>
+#elif defined(__linux)
+#include <asm/types.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
 #endif
 
 #include "meshlink_internal.h"
@@ -487,7 +491,52 @@ fail:
        return NULL;
 }
 
-#ifdef RTM_NEWADDR
+#if defined(__linux)
+static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
+       (void)flags;
+       static time_t prev_update;
+       meshlink_handle_t *mesh = data;
+
+       struct {
+               struct nlmsghdr nlm;
+               char data[2048];
+       } msg;
+
+       while(true) {
+               ssize_t result = recv(mesh->pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
+
+               if(result <= 0) {
+                       if(result == 0 || errno == EAGAIN || errno == EINTR) {
+                               break;
+                       }
+
+                       logger(mesh, MESHLINK_ERROR, "Reading from Netlink socket failed: %s\n", strerror(errno));
+                       io_set(loop, &mesh->pfroute_io, 0);
+               }
+
+               if((size_t)result < sizeof(msg.nlm)) {
+                       logger(mesh, MESHLINK_ERROR, "Invalid Netlink message\n");
+                       break;
+               }
+
+               switch(msg.nlm.nlmsg_type) {
+               case RTM_NEWLINK:
+               case RTM_DELLINK:
+               case RTM_NEWADDR:
+               case RTM_DELADDR:
+                       if(loop->now.tv_sec > prev_update + 5) {
+                               prev_update = loop->now.tv_sec;
+                               handle_network_change(mesh, 1);
+                       }
+
+                       break;
+
+               default:
+                       break;
+               }
+       }
+}
+#elif defined(RTM_NEWADDR)
 static void pfroute_io_handler(event_loop_t *loop, void *data, int flags) {
        (void)flags;
        static time_t prev_update;
@@ -561,7 +610,25 @@ bool discovery_start(meshlink_handle_t *mesh) {
 
        mesh->discovery_threadstarted = true;
 
-#ifdef RTM_NEWADDR
+#if defined(__linux)
+       int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+
+       if(sock != -1) {
+               struct sockaddr_nl sa;
+               memset(&sa, 0, sizeof(sa));
+               sa.nl_family = AF_NETLINK;
+               sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
+
+               if(bind(sock, (struct sockaddr *)&sa, sizeof(sa)) != -1) {
+                       io_add(&mesh->loop, &mesh->pfroute_io, netlink_io_handler, mesh, sock, IO_READ);
+               } else {
+                       logger(mesh, MESHLINK_WARNING, "Could not bind AF_NETLINK socket: %s", strerror(errno));
+               }
+       } else {
+               logger(mesh, MESHLINK_WARNING, "Could not open AF_NETLINK socket: %s", strerror(errno));
+       }
+
+#elif defined(RTM_NEWADDR)
        int sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
 
        if(sock != -1) {
@@ -580,15 +647,11 @@ void discovery_stop(meshlink_handle_t *mesh) {
 
        assert(mesh);
 
-#ifdef RTM_NEWADDR
-
        if(mesh->pfroute_io.cb) {
                close(mesh->pfroute_io.fd);
                io_del(&mesh->loop, &mesh->pfroute_io);
        }
 
-#endif
-
        // Shut down
        if(mesh->catta_poll) {
                catta_simple_poll_quit(mesh->catta_poll);