Fix breaking the routing table on MacOS Tahoe

Author: happyharryh

osdep/MacDNSHelper.mm

@@ -9,6 +9,7 @@
 #include "MacDNSHelper.hpp"
 
 #include <stdio.h>
+#include <sys/utsname.h>
 
 #include <SystemConfiguration/SystemConfiguration.h>
 
@@ -19,6 +20,15 @@ static void printKeys (const void* key, const void* value, void* context) {
   CFShow(value);
 }
 
+static int darwin_version_major () {
+    int version_major = -1;
+    struct utsname system_info;
+    if (uname(&system_info) == 0) {
+        sscanf(system_info.release, "%d", &version_major);
+    }
+    return version_major;
+}
+
 void MacDNSHelper::setDNS(uint64_t nwid, const char *domain, const std::vector<InetAddress> &servers)
 {
     SCDynamicStoreRef ds = SCDynamicStoreCreate(NULL, CFSTR("zerotier"), NULL, NULL);
@@ -164,8 +174,10 @@ static void printKeys (const void* key, const void* value, void* context) {
     values[3] = cfrouter;
 
 
+    // skip setting Router to avoid breaking the routing table on MacOS Tahoe and later
+    static int size = darwin_version_major() < 25 ? SIZE : SIZE - 1;
     CFDictionaryRef dict = CFDictionaryCreate(NULL,
-        (const void**)keys, (const void**)values, SIZE, &kCFCopyStringDictionaryKeyCallBacks,
+        (const void**)keys, (const void**)values, size, &kCFCopyStringDictionaryKeyCallBacks,
         &kCFTypeDictionaryValueCallBacks);
 
     // CFDictionaryApplyFunction(dict, printKeys, NULL);