Config for guild alliance only by master (#2291)

Added a new configuration to allow to restrict alliance requests to the guild master.

Thanks to @f0und3r

conf/battle/guild.conf

@@ -70,3 +70,7 @@ guild_leaderchange_delay: 1440
 // Is changing the guild leader allowed during WoE?
 // Default: no
 guild_leaderchange_woe: no
+
+// Only guild master can accept alliance?
+// Default: no
+guild_alliance_onlygm: no

src/map/battle.c

@@ -8427,6 +8427,7 @@ static const struct _battle_data {
 	{ "banana_bomb_duration",				&battle_config.banana_bomb_duration,			0,		0,		UINT16_MAX,		},
 	{ "guild_leaderchange_delay",			&battle_config.guild_leaderchange_delay,		1440,	0,		INT32_MAX,		},
 	{ "guild_leaderchange_woe",				&battle_config.guild_leaderchange_woe,			0,		0,		1,				},
+	{ "guild_alliance_onlygm",              &battle_config.guild_alliance_onlygm,           0,      0,      1, },
 	{ "feature.achievement",                &battle_config.feature_achievement,             1,      0,      1,              },
 
 #include "../custom/battle_config_init.inc"

src/map/battle.h

@@ -627,6 +627,7 @@ extern struct Battle_Config
 	int banana_bomb_duration;
 	int guild_leaderchange_delay;
 	int guild_leaderchange_woe;
+	int guild_alliance_onlygm;
 	int feature_achievement;
 
 #include "../custom/battle_config_struct.inc"

src/map/guild.c

@@ -1434,6 +1434,12 @@ int guild_reqalliance(struct map_session_data *sd,struct map_session_data *tsd)
 	if(tsd==NULL || tsd->status.guild_id<=0)
 		return 0;
 
+	// Check, is tsd guild master, if not - cancel alliance. [f0und3r]
+	if (battle_config.guild_alliance_onlygm && !tsd->state.gmaster_flag) {
+		clif_guild_allianceack(sd, 5);
+		return 0;
+	}
+
 	g[0]=sd->guild;
 	g[1]=tsd->guild;