imapc: Added imapc_max_line_length to limit maximum memory usage.

The default is still unlimited, but this should be set to something smaller
for untrusted servers.

src/lib-imap-client/imapc-client.c

@@ -69,6 +69,8 @@ imapc_client_init(const struct imapc_client_settings *set)
 		IMAPC_DEFAULT_CONNECT_TIMEOUT_MSECS;
 	client->set.cmd_timeout_msecs = set->cmd_timeout_msecs != 0 ?
 		set->cmd_timeout_msecs : IMAPC_DEFAULT_COMMAND_TIMEOUT_MSECS;
+	client->set.max_line_length = set->max_line_length != 0 ?
+		set->max_line_length : IMAPC_DEFAULT_MAX_LINE_LENGTH;
 	client->set.throttle_set = set->throttle_set;
 
 	if (client->set.throttle_set.init_msecs == 0)

src/lib-imap-client/imapc-client.h

@@ -56,6 +56,7 @@ enum imapc_client_ssl_mode {
 
 #define IMAPC_DEFAULT_CONNECT_TIMEOUT_MSECS (1000*30)
 #define IMAPC_DEFAULT_COMMAND_TIMEOUT_MSECS (1000*60*5)
+#define IMAPC_DEFAULT_MAX_LINE_LENGTH ((size_t)-1)
 
 struct imapc_throttling_settings {
 	unsigned int init_msecs;
@@ -93,6 +94,10 @@ struct imapc_client_settings {
 	   sent or received. 0 = default. */
 	unsigned int cmd_timeout_msecs;
 
+	/* Maximum allowed line length (not including literals read as
+	   streams). 0 = unlimited. */
+	size_t max_line_length;
+
 	struct imapc_throttling_settings throttle_set;
 };
 

src/lib-imap-client/imapc-connection.c

@@ -1437,11 +1437,15 @@ static void imapc_connection_input(struct imapc_connection *conn)
 		imapc_connection_input_pending(conn);
 
 	if (ret < 0) {
-		/* disconnected */
+		/* disconnected or buffer full */
 		str = t_str_new(128);
 		if (conn->disconnect_reason != NULL) {
 			str_printfa(str, "Server disconnected with message: %s",
 				    conn->disconnect_reason);
+		} else if (ret == -2) {
+			str_printfa(str, "Server sent too large input "
+				    "(buffer full at %"PRIuSIZE_T")",
+				    i_stream_get_data_size(conn->input));
 		} else if (conn->ssl_iostream == NULL) {
 			errstr = conn->input->stream_errno == 0 ? "EOF" :
 				i_stream_get_error(conn->input);
@@ -1640,7 +1644,8 @@ static void imapc_connection_connect_next_ip(struct imapc_connection *conn)
 		}
 	}
 	conn->fd = fd;
-	conn->input = conn->raw_input = i_stream_create_fd(fd, (size_t)-1);
+	conn->input = conn->raw_input =
+		i_stream_create_fd(fd, conn->client->set.max_line_length);
 	conn->output = conn->raw_output = o_stream_create_fd(fd, (size_t)-1);
 	o_stream_set_no_error_handling(conn->output, TRUE);
 
@@ -1653,7 +1658,8 @@ static void imapc_connection_connect_next_ip(struct imapc_connection *conn)
 	o_stream_set_flush_callback(conn->output, imapc_connection_output,
 				    conn);
 	conn->io = io_add(fd, IO_WRITE, imapc_connection_connected, conn);
-	conn->parser = imap_parser_create(conn->input, NULL, (size_t)-1);
+	conn->parser = imap_parser_create(conn->input, NULL,
+					  conn->client->set.max_line_length);
 	conn->to = timeout_add(conn->client->set.connect_timeout_msecs,
 			       imapc_connection_timeout, conn);
 	conn->to_output = timeout_add(conn->client->set.max_idle_time*1000,

src/lib-storage/index/imapc/imapc-settings.c

@@ -30,6 +30,7 @@ static const struct setting_define imapc_setting_defines[] = {
 	DEF(SET_STR, imapc_list_prefix),
 	DEF(SET_TIME, imapc_cmd_timeout),
 	DEF(SET_TIME, imapc_max_idle_time),
+	DEF(SET_SIZE, imapc_max_line_length),
 
 	DEF(SET_STR, pop3_deleted_flag),
 
@@ -53,6 +54,7 @@ static const struct imapc_settings imapc_default_settings = {
 	.imapc_list_prefix = "",
 	.imapc_cmd_timeout = 5*60,
 	.imapc_max_idle_time = 60*29,
+	.imapc_max_line_length = 0,
 
 	.pop3_deleted_flag = ""
 };

src/lib-storage/index/imapc/imapc-settings.h

@@ -36,6 +36,7 @@ struct imapc_settings {
 	const char *imapc_list_prefix;
 	unsigned int imapc_cmd_timeout;
 	unsigned int imapc_max_idle_time;
+	uoff_t imapc_max_line_length;
 
 	const char *pop3_deleted_flag;
 

src/lib-storage/index/imapc/imapc-storage.c

@@ -281,6 +281,7 @@ int imapc_storage_client_create(struct mail_namespace *ns,
 	set.use_proxyauth = (imapc_set->parsed_features & IMAPC_FEATURE_PROXYAUTH) != 0;
 	set.cmd_timeout_msecs = imapc_set->imapc_cmd_timeout * 1000;
 	set.max_idle_time = imapc_set->imapc_max_idle_time;
+	set.max_line_length = imapc_set->imapc_max_line_length;
 	set.dns_client_socket_path = *ns->user->set->base_dir == '\0' ? "" :
 		t_strconcat(ns->user->set->base_dir, "/",
 			    DNS_CLIENT_SOCKET_NAME, NULL);