[hackers] [quark] Fix a logic error || Laslo Hunhold

[git]

commit ed8b7e8954d302f73907f1cc302d124443f947aa
Author:     Laslo Hunhold <d...@frign.de>
AuthorDate: Mon Mar 5 01:04:51 2018 +0100
Commit:     Laslo Hunhold <d...@frign.de>
CommitDate: Mon Mar 5 01:04:51 2018 +0100

    Fix a logic error
    
    We want to xor s.host and udsname, so it especially errors out when none
    are given.

diff --git a/main.c b/main.c
index 1c7d285..bce74a0 100644
--- a/main.c
+++ b/main.c
@@ -201,8 +201,8 @@ main(int argc, char *argv[])
                usage();
        }
 
-       /* allow either host or UNIX-domain socket, force port with host */
-       if ((s.host && udsname) || (s.host && !s.port)) {
+       /* allow host xor UNIX-domain socket, force port with host */
+       if ((!s.host == !udsname) || (s.host && !s.port)) {
                usage();
        }