Make config variables a lot more useful.

- Config variables now no longer conflict with regular values.

- Config variables can now be read from the environment.
  (e.g. ${env.USER}).

- Config variables can now be used as partial values
  (e.g. support@${network.domain})

data/anope.example.conf

@@ -79,13 +79,16 @@
 /*
  * [OPTIONAL] Defines
  *
- * You can define values to other values, which can be used to easily change
- * many values in the configuration at once.
+ * You can use defines for repeated information, which can be used to easily change many
+ * values in the configuration at once.
+ *
+ * To use a define called foo.bar you use ${foo.bar} in your config file. You can also use
+ * environment variables by prefixing their name with "env." like ${env.USER}.
  */
 
 /*
  * The services.host define is used in multiple different locations throughout the
- * configuration for services clients hostnames.
+ * configuration for the server name and pseudoclient hostnames.
  */
 define
 {
@@ -211,7 +214,7 @@ serverinfo
 	 * other server names on the rest of your IRC network. Note that it does not have
 	 * to be an existing hostname, just one that isn't on your network already.
 	 */
-	name = "services.example.com"
+	name = "${services.host}"
 
 	/*
 	 * The text which should appear as the server's information in /WHOIS and similar

data/botserv.example.conf

@@ -31,7 +31,7 @@ service
 	/*
 	 * The hostname of the BotServ client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the BotServ client.

data/chanserv.example.conf

@@ -21,7 +21,7 @@ service
 	/*
 	 * The hostname of the ChanServ client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the ChanServ client.

data/global.example.conf

@@ -21,7 +21,7 @@ service
 	/*
 	 * The hostname of the Global client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the Global client.

data/hostserv.example.conf

@@ -21,7 +21,7 @@ service
 	/*
 	 * The hostname of the HostServ client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the HostServ client.

data/irc2sql.example.conf

@@ -18,7 +18,7 @@ service
 	/*
 	 * The hostname of the StatServ client.
 	 */
-	host = "stats.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the StatServ client.

data/memoserv.example.conf

@@ -21,7 +21,7 @@ service
 	/*
 	 * The hostname of the MemoServ client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the MemoServ client.

data/nickserv.example.conf

@@ -21,7 +21,7 @@ service
 	/*
 	 * The hostname of the NickServ client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the NickServ client.
@@ -210,7 +210,7 @@ module
 	 * hold a nickname.
 	 */
 	enforceruser = "enforcer"
-	enforcerhost = "services.host"
+	enforcerhost = "${services.host}"
 
 	/*
 	 * The length of time Anope should hold nicknames for.

data/operserv.example.conf

@@ -21,7 +21,7 @@ service
 	/*
 	 * The hostname of the OperServ client.
 	 */
-	host = "services.host"
+	host = "${services.host}"
 
 	/*
 	 * The realname of the OperServ client.

data/stats.standalone.example.conf

@@ -79,17 +79,20 @@
 /*
  * [OPTIONAL] Defines
  *
- * You can define values to other values, which can be used to easily change
- * many values in the configuration at once.
+ * You can use defines for repeated information, which can be used to easily change many
+ * values in the configuration at once.
+ *
+ * To use a define called foo.bar you use ${foo.bar} in your config file. You can also use
+ * environment variables by prefixing their name with "env." like ${env.USER}.
  */
 
 /*
- * The stats.host define is used in multiple different locations throughout the
- * configuration for the stats client hostname.
+ * The services.host define is used in multiple different locations throughout the
+ * configuration for the server name and pseudoclient hostnames.
  */
 define
 {
-	name = "stats.host"
+	name = "services.host"
 	value = "stats.example.com"
 }
 
@@ -208,7 +211,7 @@ serverinfo
 	 * other server names on the rest of your IRC network. Note that it does not have
 	 * to be an existing hostname, just one that isn't on your network already.
 	 */
-	name = "stats.example.com"
+	name = "${services.host}"
 
 	/*
 	 * The text which should appear as the server's information in /WHOIS and similar

include/config.h

@@ -83,9 +83,14 @@ namespace Configuration
 
 	struct Uplink;
 
-	struct CoreExport Conf final
-		: Block
+	class CoreExport Conf final
+		: public Block
 	{
+	private:
+		/** Replaces defined variables within a string. */
+		Anope::string ReplaceVars(const Anope::string &str, const File &file, int linenumber);
+
+	public:
 		/* options:readtimeout */
 		time_t ReadTimeout;
 		/* If we should default to privmsging clients */

src/config.cpp

@@ -939,24 +939,12 @@ void Conf::LoadConf(File &file)
 					}
 
 					Block *b = block_stack.top();
-
 					if (b)
-						Log(LOG_DEBUG) << "ln " << linenumber << " EOL: s='" << b->name << "' '" << itemname << "' set to '" << wordbuffer << "'";
-
-					/* Check defines */
-					for (int i = 0; i < this->CountBlock("define"); ++i)
 					{
-						const Block &define = this->GetBlock("define", i);
-
-						const Anope::string &dname = define.Get<const Anope::string>("name");
-
-						if (dname == wordbuffer && &define != b)
-							wordbuffer = define.Get<const Anope::string>("value");
+						Log(LOG_DEBUG) << "ln " << linenumber << " EOL: s='" << b->name << "' '" << itemname << "' set to '" << wordbuffer << "'";
+						b->items[itemname] = ReplaceVars(wordbuffer, file, linenumber);
 					}
 
-					if (b)
-						b->items[itemname] = wordbuffer;
-
 					wordbuffer.clear();
 					itemname.clear();
 				}
@@ -991,3 +979,52 @@ void Conf::LoadConf(File &file)
 			throw ConfigException("Unterminated commented block at end of file: " + file.GetName());
 	}
 }
+
+Anope::string Conf::ReplaceVars(const Anope::string &str, const File &file, int linenumber)
+{
+	Anope::string ret;
+	for (auto it = str.begin(); it != str.end(); )
+	{
+		if (*it != '$')
+		{
+			ret.push_back(*it++);
+			continue;
+		}
+
+		if (++it == str.end() || *it != '{')
+			continue;
+
+		it++;
+		Anope::string var;
+		while (it != str.end() && *it != '}')
+			var.push_back(*it++);
+
+		if (it == str.end())
+			throw ConfigException("Unterminated variable: " + file.GetName() + ":" + Anope::ToString(linenumber));
+
+		it++;
+		if (var.compare(0, 4, "env.", 4) == 0)
+		{
+			// This is an environment variable rather than a defined variable
+			const char* envstr = getenv(var.c_str() + 4);
+			if (envstr && envstr)
+				ret.append(envstr);
+			continue;
+		}
+
+		for (int i = 0; i < this->CountBlock("define"); ++i)
+		{
+			const auto &define = this->GetBlock("define", i);
+			const auto defname = define.Get<const Anope::string>("name");
+			if (defname == var)
+			{
+				ret.append(define.Get<const Anope::string>("value"));
+				break;
+			}
+		}
+	}
+
+	if (!str.equals_cs(ret))
+		Log(LOG_DEBUG) << "Expanded \"" << str << "\" to \"" << ret << "\"";
+	return ret;
+}