Monitor a PFROUTE socket on *BSD and macOS.

Catta is not handling network changes correctly on *BSD and macOS. In
particular, after the initial startup, interfaces that go up and down
do not cause a callback to be generated, so MeshLink is not notified of
the changes.

To ensure MeshLink responds rapidly to network changes on these
platforms, we open a PFROUTE socket and monitor it ourself. We only
check the message type, and don't track exactly what addresses get added
or removed.

diff --git a/src/discovery.c b/src/discovery.c
index 7b6cfd0a96f3f4893c2a072897ac4f752bcd07b1..8fa3aa3164a53b1f8f5a8807f572c3d9cffb802b 100644 (file)
--- a/src/discovery.c
+++ b/src/discovery.c
@@ -9,7 +9,12 @@
 #include <catta/alternative.h>
 #include <catta/error.h>
 
+#if defined(__APPLE__) || defined(__unix) && !defined(__linux)
+#include <net/route.h>
+#endif
+
 #include "meshlink_internal.h"
+#include "event.h"
 #include "discovery.h"
 #include "sockaddr.h"
 #include "logger.h"
@@ -453,6 +458,53 @@ fail:
        return NULL;
 }
 
+#ifdef RTM_NEWADDR
+static void pfroute_io_handler(event_loop_t *loop, void *data, int flags) {
+       (void)flags;
+       static time_t prev_update;
+       meshlink_handle_t *mesh = data;
+
+       struct {
+               struct rt_msghdr rtm;
+               char data[2048];
+       } msg;
+
+       while(true) {
+               msg.rtm.rtm_version = 0;
+               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 PFROUTE socket failed: %s\n", strerror(errno));
+                       io_set(loop, &mesh->pfroute_io, 0);
+               }
+
+               if(msg.rtm.rtm_version != RTM_VERSION) {
+                       logger(mesh, MESHLINK_ERROR, "Invalid PFROUTE message version\n");
+                       break;
+               }
+
+               switch(msg.rtm.rtm_type) {
+               case RTM_IFINFO:
+               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;
+               }
+       }
+}
+#endif
+
 bool discovery_start(meshlink_handle_t *mesh) {
        logger(mesh, MESHLINK_DEBUG, "discovery_start called\n");
 
@@ -478,6 +530,17 @@ bool discovery_start(meshlink_handle_t *mesh) {
 
        mesh->discovery_threadstarted = true;
 
+#ifdef RTM_NEWADDR
+       int sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
+
+       if(sock != -1) {
+               io_add(&mesh->loop, &mesh->pfroute_io, pfroute_io_handler, mesh, sock, IO_READ);
+       } else {
+               logger(mesh, MESHLINK_WARNING, "Could not open PF_ROUTE socket: %s", strerror(errno));
+       }
+
+#endif
+
        return true;
 }
 
@@ -486,6 +549,15 @@ 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);

diff --git a/src/meshlink_internal.h b/src/meshlink_internal.h
index d6dc87d04f414d7149fdfea3e190342cb728fa15..a96050bfff1636e0ebc845e738ce0e2f88846a00 100644 (file)
--- a/src/meshlink_internal.h
+++ b/src/meshlink_internal.h
@@ -185,6 +185,9 @@ struct meshlink_handle {
        char *catta_servicetype;
        unsigned int catta_interfaces;
 
+       // PFROUTE
+       io_t pfroute_io;
+
        // ADNS
        pthread_t adns_thread;
        pthread_cond_t adns_cond;