wg-quick: use addconf instead of setconf

The example in the man page at some point changed:

-    \fBPostUp = wg set %i private-key <(pass WireGuard/private-keys/%i)\fP
+    \fBPreUp = wg set %i private-key <(pass WireGuard/private-keys/%i)\fP

This is actually wrong because PreUp is followed by set_config(), which
calls `wg setconf`, which in turn deletes the private key from the
interface because it is missing from the configuration. Replacing this
with `wg addconf` is safe to do because the interface is newly created.

Suggested-by: Matthias Dressel <code@deadcode.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Author: zx2c4

src/wg-quick/android.c

@@ -1047,7 +1047,7 @@ static void set_routes(const char *iface, unsigned int netid)
 static void set_config(const char *iface, const char *config)
 {
 	FILE *config_writer;
-	_cleanup_free_ char *cmd = concat("wg setconf ", iface, " /proc/self/fd/0", NULL);
+	_cleanup_free_ char *cmd = concat("wg addconf ", iface, " /proc/self/fd/0", NULL);
 	int ret;
 
 	printf("[#] %s\n", cmd);

src/wg-quick/darwin.bash

@@ -370,7 +370,7 @@ add_route() {
 }
 
 set_config() {
-	cmd wg setconf "$REAL_INTERFACE" <(echo "$WG_CONFIG")
+	cmd wg addconf "$REAL_INTERFACE" <(echo "$WG_CONFIG")
 }
 
 save_config() {

src/wg-quick/freebsd.bash

@@ -338,7 +338,7 @@ add_route() {
 }
 
 set_config() {
-	echo "$WG_CONFIG" | cmd wg setconf "$INTERFACE" /dev/stdin
+	echo "$WG_CONFIG" | cmd wg addconf "$INTERFACE" /dev/stdin
 }
 
 save_config() {

src/wg-quick/linux.bash

@@ -249,7 +249,7 @@ add_default() {
 }
 
 set_config() {
-	cmd wg setconf "$INTERFACE" <(echo "$WG_CONFIG")
+	cmd wg addconf "$INTERFACE" <(echo "$WG_CONFIG")
 }
 
 save_config() {

src/wg-quick/openbsd.bash

@@ -338,7 +338,7 @@ add_route() {
 }
 
 set_config() {
-	cmd wg setconf "$REAL_INTERFACE" <(echo "$WG_CONFIG")
+	cmd wg addconf "$REAL_INTERFACE" <(echo "$WG_CONFIG")
 }
 
 save_config() {