FIX: crash when re-opening listening port multiple times

fixes: Oldes/Rebol-issues#2445

Author: Oldes

src/os/dev-net.c

@@ -260,6 +260,7 @@ static REBOOL Nonblocking_Mode(SOCKET sock)
 			if (sock->handle) WSACancelAsyncRequest(sock->handle);
 #endif
 			OS_Free(sock->net.host_info);
+			sock->net.host_info = NULL;
 			sock->socket = sock->length; // Restore TCP socket (see Lookup)
 		}
 

src/tests/units/crash-test.r3

@@ -170,6 +170,13 @@ Rebol [
 --test-- "issue-441"
 	;@@ https://github.com/Oldes/Rebol-issues/issues/441
 	--assert unset? repeat n 1000000 [foreach a [1 2 3] []] ;- no crash
+
+--test-- "issue-2445"
+	;@@ https://github.com/Oldes/Rebol-issues/issues/2445
+	--assert not error? try [p: open tcp://localhost:10000]
+	loop 10 [--assert not error? try [close p open p]] ;- no crash
+	--assert not error? try [close p]
+
 ===end-group===
 
 ~~~end-file~~~