imap: Implemented support for the LITERAL- capability.

This replaces the LITERAL+ capability when the imap_literal_minus setting is enabled.

configure.ac

@@ -778,7 +778,7 @@ dnl **
 
 dnl IDLE doesn't really belong to banner. It's there just to make Blackberries
 dnl happy, because otherwise BIS server disables push email.
-capability_banner="IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE"
+capability_banner="IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE"
 capability="$capability_banner SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS THREAD=ORDEREDSUBJECT MULTIAPPEND URL-PARTIAL CATENATE UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS BINARY MOVE"
 AC_DEFINE_UNQUOTED(CAPABILITY_STRING, "$capability", [IMAP capabilities])
 AC_DEFINE_UNQUOTED(CAPABILITY_BANNER_STRING, "$capability_banner", [IMAP capabilities advertised in banner])

doc/example-config/conf.d/20-imap.conf

@@ -68,6 +68,9 @@
 # Host allowed in URLAUTH URLs sent by client. "*" allows all.
 #imap_urlauth_host =
 
+# Enable IMAP LITERAL- extension (replaces LITERAL+)
+#imap_literal_minus = no
+
 protocol imap {
   # Space separated list of plugins to load (default is global mail_plugins).
   #mail_plugins = $mail_plugins

src/imap-login/imap-login-client.c

@@ -97,17 +97,26 @@ static const char *get_capability(struct client *client)
 {
 	struct imap_client *imap_client = (struct imap_client *)client;
 	string_t *cap_str = t_str_new(256);
+	bool explicit_capability = FALSE;
 
 	if (*imap_client->set->imap_capability == '\0')
 		str_append(cap_str, CAPABILITY_BANNER_STRING);
-	else if (*imap_client->set->imap_capability != '+')
+	else if (*imap_client->set->imap_capability != '+') {
+		explicit_capability = TRUE;
 		str_append(cap_str, imap_client->set->imap_capability);
-	else {
+	} else {
 		str_append(cap_str, CAPABILITY_BANNER_STRING);
 		str_append_c(cap_str, ' ');
 		str_append(cap_str, imap_client->set->imap_capability + 1);
 	}
 
+	if (!explicit_capability) {
+		if (imap_client->set->imap_literal_minus)
+			str_append(cap_str, " LITERAL-");
+		else
+			str_append(cap_str, " LITERAL+");
+	}
+
 	if (client_is_tls_enabled(client) && !client->tls)
 		str_append(cap_str, " STARTTLS");
 	if (is_login_cmd_disabled(client))
@@ -277,6 +286,8 @@ static int cmd_id(struct imap_client *client)
 		id->parser = imap_parser_create(client->common.input,
 						client->common.output,
 						MAX_IMAP_LINE);
+		if (client->set->imap_literal_minus)
+			imap_parser_enable_literal_minus(id->parser);
 		parser_flags = IMAP_PARSE_FLAG_STOP_AT_LIST;
 	} else {
 		id = client->cmd_id;
@@ -543,6 +554,8 @@ static void imap_client_create(struct client *client, void **other_sets)
 	imap_client->parser =
 		imap_parser_create(imap_client->common.input,
 				   imap_client->common.output, MAX_IMAP_LINE);
+	if (imap_client->set->imap_literal_minus)
+		imap_parser_enable_literal_minus(imap_client->parser);
 	client->io = io_add(client->fd, IO_READ, client_input, client);
 }
 

src/imap-login/imap-login-settings.c

@@ -57,14 +57,16 @@ static const struct setting_define imap_login_setting_defines[] = {
 	DEF(SET_STR, imap_capability),
 	DEF(SET_STR, imap_id_send),
 	DEF(SET_STR, imap_id_log),
+	DEF(SET_BOOL, imap_literal_minus),
 
 	SETTING_DEFINE_LIST_END
 };
 
 static const struct imap_login_settings imap_login_default_settings = {
 	.imap_capability = "",
 	.imap_id_send = "name *",
-	.imap_id_log = ""
+	.imap_id_log = "",
+	.imap_literal_minus = FALSE
 };
 
 static const struct setting_parser_info *imap_login_setting_dependencies[] = {

src/imap-login/imap-login-settings.h

@@ -5,6 +5,7 @@ struct imap_login_settings {
 	const char *imap_capability;
 	const char *imap_id_send;
 	const char *imap_id_log;
+	bool imap_literal_minus;
 };
 
 extern const struct setting_parser_info *imap_login_setting_roots[];

src/imap/cmd-append.c

@@ -418,7 +418,10 @@ static bool cmd_append_continue_catenate(struct client_command_context *cmd)
 		case IMAP_PARSE_ERROR_NONE:
 			i_unreached();
 		case IMAP_PARSE_ERROR_LITERAL_TOO_BIG:
-			client_disconnect_with_error(client, msg);
+			client_send_line(client, t_strconcat("* BYE ",
+				(client->set->imap_literal_minus ? "[TOOBIG] " : ""),
+				msg, NULL));
+			client_disconnect(client, msg);
 			break;
 		default:
 			if (!ctx->failed)
@@ -761,7 +764,10 @@ static bool cmd_append_parse_new_msg(struct client_command_context *cmd)
 			case IMAP_PARSE_ERROR_NONE:
 				i_unreached();
 			case IMAP_PARSE_ERROR_LITERAL_TOO_BIG:
-				client_disconnect_with_error(client, msg);
+				client_send_line(client, t_strconcat("* BYE ",
+					(client->set->imap_literal_minus ? "[TOOBIG] " : ""),
+					msg, NULL));
+				client_disconnect(client, msg);
 				break;
 			default:
 				client_send_command_error(cmd, msg);
@@ -936,6 +942,8 @@ bool cmd_append(struct client_command_context *cmd)
 
 	ctx->save_parser = imap_parser_create(client->input, client->output,
 					      client->set->imap_max_line_length);
+	if (client->set->imap_literal_minus)
+		imap_parser_enable_literal_minus(ctx->save_parser);
 
 	cmd->func = cmd_append_parse_new_msg;
 	cmd->context = ctx;

src/imap/cmd-setmetadata.c

@@ -278,6 +278,8 @@ cmd_setmetadata_start(struct imap_setmetadata_context *ctx)
 	client->input_lock = cmd;
 	ctx->parser = imap_parser_create(client->input, client->output,
 					 client->set->imap_max_line_length);
+	if (client->set->imap_literal_minus)
+		imap_parser_enable_literal_minus(ctx->parser);
 	o_stream_unset_flush_callback(client->output);
 
 	cmd->func = cmd_setmetadata_continue;

src/imap/imap-client.c

@@ -139,6 +139,12 @@ struct client *client_create(int fd_in, int fd_out, const char *session_id,
 		str_append_c(client->capability_string, ' ');
 		str_append(client->capability_string, set->imap_capability + 1);
 	}
+	if (!explicit_capability) {
+		if (client->set->imap_literal_minus)
+			str_append(client->capability_string, " LITERAL-");
+		else
+			str_append(client->capability_string, " LITERAL+");
+	}
 	if (user->fuzzy_search && !explicit_capability) {
 		/* Enable FUZZY capability only when it actually has
 		   a chance of working */
@@ -756,6 +762,8 @@ client_command_new(struct client *client)
 		cmd->parser =
 			imap_parser_create(client->input, client->output,
 					   client->set->imap_max_line_length);
+		if (client->set->imap_literal_minus)
+			imap_parser_enable_literal_minus(cmd->parser);
 	}
 	return cmd;
 }

src/imap/imap-settings.c

@@ -71,6 +71,7 @@ static const struct setting_define imap_setting_defines[] = {
 	DEF(SET_STR, imap_id_send),
 	DEF(SET_STR, imap_id_log),
 	DEF(SET_BOOL, imap_metadata),
+	DEF(SET_BOOL, imap_literal_minus),
 	DEF(SET_TIME, imap_hibernate_timeout),
 
 	DEF(SET_STR, imap_urlauth_host),
@@ -96,6 +97,7 @@ static const struct imap_settings imap_default_settings = {
 	.imap_id_send = "name *",
 	.imap_id_log = "",
 	.imap_metadata = FALSE,
+	.imap_literal_minus = FALSE,
 	.imap_hibernate_timeout = 0,
 
 	.imap_urlauth_host = "",

src/imap/imap-settings.h

@@ -25,6 +25,7 @@ struct imap_settings {
 	const char *imap_id_send;
 	const char *imap_id_log;
 	bool imap_metadata;
+	bool imap_literal_minus;
 	unsigned int imap_hibernate_timeout;
 
 	/* imap urlauth: */

src/lib-imap/imap-parser.c

@@ -57,6 +57,7 @@ struct imap_parser {
 	enum imap_parser_error error;
 	const char *error_msg;
 
+	unsigned int literal_minus:1;
 	unsigned int literal_skip_crlf:1;
 	unsigned int literal_nonsync:1;
 	unsigned int literal8:1;
@@ -104,6 +105,11 @@ void imap_parser_unref(struct imap_parser **parser)
 	*parser = NULL;
 }
 
+void imap_parser_enable_literal_minus(struct imap_parser *parser)
+{
+	parser->literal_minus = TRUE;
+}
+
 void imap_parser_reset(struct imap_parser *parser)
 {
 	p_clear(parser->pool);
@@ -387,6 +393,13 @@ static int imap_parser_read_string(struct imap_parser *parser,
 
 static int imap_parser_literal_end(struct imap_parser *parser)
 {
+	if (parser->literal_minus && parser->literal_nonsync &&
+		parser->literal_size > 4096) {
+		parser->error_msg = "Non-synchronizing literal size too large";
+		parser->error = IMAP_PARSE_ERROR_LITERAL_TOO_BIG;
+		return FALSE;
+	}
+
 	if ((parser->flags & IMAP_PARSE_FLAG_LITERAL_SIZE) == 0) {
 		if (parser->line_size >= parser->max_line_size ||
 		    parser->literal_size >

src/lib-imap/imap-parser.h

@@ -57,6 +57,10 @@ imap_parser_create(struct istream *input, struct ostream *output,
 void imap_parser_ref(struct imap_parser *parser);
 void imap_parser_unref(struct imap_parser **parser);
 
+/* Enable LITERAL- parser semantics: non-synchronizing literals must not
+   exceed 4096 bytes */
+void imap_parser_enable_literal_minus(struct imap_parser *parser);
+
 /* Reset the parser to initial state. */
 void imap_parser_reset(struct imap_parser *parser);