add HELPER_PATH to default configs

src/dns/dns.conf.in

@@ -32,3 +32,7 @@ IPV4MASK = 255.255.0.0
 # public DNS resolver or your ISP's resolver from /etc/resolv.conf.
 DNS_EXIT = 8.8.8.8
 
+# Location of the helper binary gnunet-helper-dns (setuid flag required).
+# By default it is assumed to be in the libexec directory, but on some systems
+# like NixOS setuid is only possible through a wrapper in a different location.
+HELPER_PATH =

src/exit/exit.conf

@@ -66,3 +66,8 @@ ENABLE_IPV6 = YES
 
 # Maximum number of concurrent connections this exit supports.
 MAX_CONNECTIONS = 256
+
+# Location of the helper binary gnunet-helper-exit (setuid flag required).
+# By default it is assumed to be in the libexec directory, but on some systems
+# like NixOS setuid is only possible through a wrapper in a different location.
+HELPER_PATH =

src/nat/nat.conf.in

@@ -38,3 +38,8 @@ STUN_SERVERS = stun.gnunet.org stun.services.mozilla.com:3478 stun.ekiga.net:347
 # After how long do we consider STUN data stale?
 STUN_STALE = 60 min
 
+# Location of the helper binaries gnunet-helper-nat-client and
+# gnunet-helper-nat-server (setuid flag required).
+# By default it is assumed to be in the libexec directory, but on some systems like
+# NixOS setuid is only possible through a wrapper in a different location.
+HELPER_PATH =

src/vpn/vpn.conf.in

@@ -17,3 +17,7 @@ VIRTDNS = 10.11.10.2
 VIRTDNS6 = 1234::17
 IFNAME = vpn-gnunet
 
+# Location of the helper binary gnunet-helper-vpn (setuid flag required).
+# By default it is assumed to be in the libexec directory, but on some systems
+# like NixOS setuid is only possible through a wrapper in a different location.
+HELPER_PATH =