wip: migrate to mono-repo. SPN has already been moved to spn/

spn/captain/exceptions.go

@@ -0,0 +1,28 @@
+package captain
+
+import (
+	"net"
+	"sync"
+)
+
+var (
+	exceptionLock sync.Mutex
+	exceptIPv4    net.IP
+	exceptIPv6    net.IP
+)
+
+func setExceptions(ipv4, ipv6 net.IP) {
+	exceptionLock.Lock()
+	defer exceptionLock.Unlock()
+
+	exceptIPv4 = ipv4
+	exceptIPv6 = ipv6
+}
+
+// IsExcepted checks if the given IP is currently excepted from the SPN.
+func IsExcepted(ip net.IP) bool {
+	exceptionLock.Lock()
+	defer exceptionLock.Unlock()
+
+	return ip.Equal(exceptIPv4) || ip.Equal(exceptIPv6)
+}