lib-smtp: server: Add support for adding (non-standard) extra capabil…

…ities.

src/lib-smtp/smtp-server-cmd-helo.c

@@ -2,6 +2,7 @@
 
 #include "lib.h"
 #include "str.h"
+#include "array.h"
 #include "smtp-syntax.h"
 
 #include "smtp-server-private.h"
@@ -129,8 +130,29 @@ void smtp_server_cmd_helo(struct smtp_server_cmd_ctx *cmd,
 struct smtp_server_reply *
 smtp_server_cmd_ehlo_reply_create(struct smtp_server_cmd_ctx *cmd)
 {
+	static struct {
+		const char *name;
+		void (*add)(struct smtp_server_reply *reply);
+	} standard_caps[] = {
+		/* Sorted alphabetically */
+		{ "8BITMIME", smtp_server_reply_ehlo_add_8bitmime },
+		{ "BINARYMIME", smtp_server_reply_ehlo_add_binarymime },
+		{ "CHUNKING", smtp_server_reply_ehlo_add_chunking },
+		{ "DSN", smtp_server_reply_ehlo_add_dsn },
+		{ "ENHANCEDSTATUSCODES",
+		  smtp_server_reply_ehlo_add_enhancedstatuscodes },
+		{ "PIPELINING", smtp_server_reply_ehlo_add_pipelining },
+		{ "SIZE", smtp_server_reply_ehlo_add_size },
+		{ "STARTTLS", smtp_server_reply_ehlo_add_starttls },
+		{ "VRFY", smtp_server_reply_ehlo_add_vrfy },
+		{ "XCLIENT", smtp_server_reply_ehlo_add_xclient }
+	};
+	const unsigned int standard_caps_count = N_ELEMENTS(standard_caps);
+	struct smtp_server_connection *conn = cmd->conn;
 	struct smtp_server_command *command = cmd->cmd;
 	struct smtp_server_cmd_helo *helo_data = command->data;
+	const struct smtp_capability_extra *extra_caps = NULL;
+	unsigned int extra_caps_count, i, j;
 	struct smtp_server_reply *reply;
 
 	i_assert(cmd->cmd->reg->func == smtp_server_cmd_ehlo);
@@ -139,17 +161,27 @@ smtp_server_cmd_ehlo_reply_create(struct smtp_server_cmd_ctx *cmd)
 	if (helo_data->helo.old_smtp)
 		return reply;
 
-	smtp_server_reply_ehlo_add_8bitmime(reply);
-	smtp_server_reply_ehlo_add_binarymime(reply);
-	smtp_server_reply_ehlo_add_chunking(reply);
-	smtp_server_reply_ehlo_add_dsn(reply);
-	smtp_server_reply_ehlo_add_enhancedstatuscodes(reply);
-	smtp_server_reply_ehlo_add_pipelining(reply);
-	smtp_server_reply_ehlo_add_size(reply);
-	smtp_server_reply_ehlo_add_starttls(reply);
-	smtp_server_reply_ehlo_add_vrfy(reply);
-	smtp_server_reply_ehlo_add_xclient(reply);
+	extra_caps_count = 0;
+	if (array_is_created(&conn->extra_capabilities)) {
+		extra_caps = array_get(&conn->extra_capabilities,
+				       &extra_caps_count);
+	}
 
+	i = j = 0;
+	while (i < standard_caps_count || j < extra_caps_count) {
+		if (i < standard_caps_count && 
+		    (j >= extra_caps_count ||
+		     strcasecmp(standard_caps[i].name,
+				extra_caps[j].name) < 0)) {
+			standard_caps[i].add(reply);
+			i++;
+		} else {
+			smtp_server_reply_ehlo_add_params(
+				reply, extra_caps[j].name,
+				extra_caps[j].params);
+			j++;
+		}
+	}
 	return reply;
 }
 

src/lib-smtp/smtp-server-connection.c

@@ -14,6 +14,7 @@
 #include "master-service.h"
 #include "master-service-ssl.h"
 
+#include "smtp-syntax.h"
 #include "smtp-reply-parser.h"
 #include "smtp-command-parser.h"
 #include "smtp-server-private.h"
@@ -1436,6 +1437,49 @@ void smtp_server_connection_set_capabilities(
 	conn->set.capabilities = capabilities;
 }
 
+void smtp_server_connection_add_extra_capability(
+	struct smtp_server_connection *conn,
+	const struct smtp_capability_extra *cap)
+{
+	const struct smtp_capability_extra *cap_idx;
+	struct smtp_capability_extra cap_new;
+	unsigned int insert_idx;
+	pool_t pool = conn->pool;
+
+	/* Avoid committing protocol errors */
+	i_assert(smtp_ehlo_keyword_is_valid(cap->name));
+	i_assert(smtp_ehlo_params_are_valid(cap->params));
+
+	/* Cannot override standard capabiltiies */
+	i_assert(smtp_capability_find_by_name(cap->name)
+		 == SMTP_CAPABILITY_NONE);
+
+	if (!array_is_created(&conn->extra_capabilities))
+		p_array_init(&conn->extra_capabilities, pool, 4);
+
+	/* Keep array sorted */
+	insert_idx = array_count(&conn->extra_capabilities);
+	array_foreach(&conn->extra_capabilities, cap_idx) {
+		int cmp = strcasecmp(cap_idx->name, cap->name);
+
+		/* Prohibit duplicates */
+		i_assert(cmp != 0);
+
+		if (cmp > 0) {
+			insert_idx = array_foreach_idx(
+				&conn->extra_capabilities, cap_idx);
+			break;
+		}
+	}
+
+	i_zero(&cap_new);
+	cap_new.name = p_strdup(pool, cap->name);
+	if (cap->params != NULL)
+		cap_new.params = p_strarray_dup(pool, cap->params);
+
+	array_insert(&conn->extra_capabilities, insert_idx, &cap_new, 1);
+}
+
 void *smtp_server_connection_get_context(struct smtp_server_connection *conn)
 {
 	return conn->context;

src/lib-smtp/smtp-server-private.h

@@ -144,6 +144,7 @@ struct smtp_server_connection {
 
 	struct smtp_server_settings set;
 
+	ARRAY(struct smtp_capability_extra) extra_capabilities;
 	ARRAY_TYPE(const_string) mail_param_extensions; /* NULL-terminated */
 	ARRAY_TYPE(const_string) rcpt_param_extensions; /* NULL-terminated */
 

src/lib-smtp/smtp-server.h

@@ -427,6 +427,9 @@ void smtp_server_connection_get_proxy_data(struct smtp_server_connection *conn,
 
 void smtp_server_connection_set_capabilities(
 	struct smtp_server_connection *conn, enum smtp_capability capabilities);
+void smtp_server_connection_add_extra_capability(
+	struct smtp_server_connection *conn,
+	const struct smtp_capability_extra *cap);
 
 void smtp_server_connection_register_mail_param(
 	struct smtp_server_connection *conn, const char *param);