lib-dict: Add support for lookup to return multiple values

Implements only the initial stubs to the drivers.

src/lib-dict/dict-client.c

@@ -927,6 +927,7 @@ client_dict_lookup_async_callback(struct client_dict_cmd *cmd,
 {
 	struct client_dict *dict = cmd->dict;
 	struct dict_lookup_result result;
+	const char *const values[] = { value, NULL };
 
 	i_zero(&result);
 	if (error != NULL) {
@@ -935,6 +936,7 @@ client_dict_lookup_async_callback(struct client_dict_cmd *cmd,
 	} else switch (reply) {
 	case DICT_PROTOCOL_REPLY_OK:
 		result.value = value;
+		result.values = values;
 		result.ret = 1;
 		break;
 	case DICT_PROTOCOL_REPLY_NOTFOUND:

src/lib-dict/dict-sql.c

@@ -479,6 +479,7 @@ sql_dict_lookup_async_callback(struct sql_result *sql_result,
 			       struct sql_dict_lookup_context *ctx)
 {
 	struct dict_lookup_result result;
+	const char *values[2] = { NULL, NULL };
 
 	i_zero(&result);
 	result.ret = sql_result_next_row(sql_result);
@@ -492,6 +493,9 @@ sql_dict_lookup_async_callback(struct sql_result *sql_result,
 			   "not found", which is probably what is usually
 			   wanted. */
 			result.ret = 0;
+		} else {
+			values[0] = result.value;
+			result.values = values;
 		}
 	}
 	ctx->callback(&result, ctx->context);

src/lib-dict/dict.c

@@ -138,6 +138,8 @@ void dict_lookup_async(struct dict *dict, const char *key,
 					 key, &result.value);
 		if (result.ret < 0)
 			result.error = "Lookup failed";
+		const char *const values[] = { result.value, NULL };
+		result.values = values;
 		callback(&result, context);
 		return;
 	}

src/lib-dict/dict.h

@@ -40,7 +40,13 @@ struct dict_settings {
 
 struct dict_lookup_result {
 	int ret;
+
+	/* First returned value (ret > 0) */
 	const char *value;
+	/* NULL-terminated list of all returned values (ret > 0) */
+	const char *const *values;
+
+	/* Error message for a failed lookup (ret < 0) */
 	const char *error;
 };
 

src/plugins/dict-ldap/dict-ldap.c

@@ -297,10 +297,15 @@ ldap_dict_lookup_callback(struct ldap_result *result, struct dict_ldap_op *op)
 			/* try extract value */
 			const char *const *values = ldap_entry_get_attribute(entry, op->map->value_attribute);
 			if (values != NULL) {
+				const char **new_values;
+
 				if (op->dict->set->debug > 0)
 					i_debug("ldap_dict_lookup_callback got attribute %s", op->map->value_attribute);
 				op->res.ret = 1;
-				op->res.value = p_strdup(op->pool, values[0]);
+				new_values = p_new(op->pool, const char *, 2);
+				new_values[0] = p_strdup(op->pool, values[0]);
+				op->res.values = new_values;
+				op->res.value = op->res.values[0];
 			} else {
 				if (op->dict->set->debug > 0)
 					i_debug("ldap_dict_lookup_callback dit not get attribute %s", op->map->value_attribute);