imap: Integrated new capability list API

Updated imap to use the new capability list API from lib-imap which will
allow for post-login imap capabilities to be displayed conditionally.
This ensures functionality of client_add_capability() does not change,
and it introduces a new imap function client_get_capability() which is
now used everywhere that client->capability_string was previously used.

Author: shaun-a-johnson

src/imap/cmd-capability.c

@@ -7,7 +7,7 @@
 bool cmd_capability(struct client_command_context *cmd)
 {
 	client_send_line(cmd->client, t_strconcat(
-		"* CAPABILITY ", str_c(cmd->client->capability_string), NULL));
+		"* CAPABILITY ", client_get_capability(cmd->client), NULL));
 
 	client_send_tagline(cmd, "OK Capability completed.");
 	return TRUE;

src/imap/imap-client.c

@@ -25,6 +25,7 @@
 #include "imap-notify.h"
 #include "imap-commands.h"
 #include "imap-feature.h"
+#include "imap-capability-list.h"
 
 #include <unistd.h>
 
@@ -161,17 +162,22 @@ struct client *client_create(int fd_in, int fd_out, const char *session_id,
 					     &client->output);
 	}
 
-	client->capability_string =
-		str_new(client->pool, sizeof(CAPABILITY_STRING)+64);
+	/* create our capability list */
+	client->capability_list = imap_capability_list_create(NULL);
 
 	if (*set->imap_capability == '\0')
-		str_append(client->capability_string, CAPABILITY_STRING);
+		imap_capability_list_append_string(client->capability_list,
+						   CAPABILITY_STRING);
 	else if (*set->imap_capability != '+') {
-		str_append(client->capability_string, set->imap_capability);
+		imap_capability_list_append_string(client->capability_list,
+						   set->imap_capability);
 	} else {
-		str_append(client->capability_string, CAPABILITY_STRING);
-		str_append_c(client->capability_string, ' ');
-		str_append(client->capability_string, set->imap_capability + 1);
+		/* add the capability banner string to the cap list */
+		imap_capability_list_append_string(client->capability_list,
+						   CAPABILITY_STRING);
+		/* add everything after the plus to our cap list */
+		imap_capability_list_append_string(client->capability_list,
+						   client->set->imap_capability + 1);
 	}
 	if (client->set->imap_literal_minus)
 		client_add_capability(client, "LITERAL-");
@@ -565,8 +571,36 @@ void client_add_capability(struct client *client, const char *capability)
 		/* explicit capability - don't change it */
 		return;
 	}
-	str_append_c(client->capability_string, ' ');
-	str_append(client->capability_string, capability);
+
+	/* add it to our capability list as CAP_ALWAYS */
+	imap_capability_list_add(client->capability_list,
+				 capability, IMAP_CAP_VISIBILITY_ALWAYS);
+}
+
+const char *client_get_capability(struct client *client)
+{
+	string_t *cap_str = t_str_new(256);
+
+	/* imap is postauth by definition */
+	enum imap_capability_visibility visibility = IMAP_CAP_VISIBILITY_POSTAUTH;
+
+	/* is the client secured by means of ssl? */
+	if (client->ssl_secured)
+		visibility |= IMAP_CAP_VISIBILITY_TLS_ACTIVE;
+	else
+		visibility |= IMAP_CAP_VISIBILITY_TLS_INACTIVE;
+
+	/* Are we secured? (localhost? tls? etc) */
+	if (client->secured)
+		visibility |= IMAP_CAP_VISIBILITY_SECURE;
+	else
+		visibility |= IMAP_CAP_VISIBILITY_INSECURE;
+
+	/* build capability string based on IMAP_CAP_VISIBILITY_ flags */
+	imap_capability_list_get_capability(client->capability_list,
+					    cap_str, visibility);
+
+	return str_c(cap_str);
 }
 
 void client_send_line(struct client *client, const char *data)

src/imap/imap-client.h

@@ -166,7 +166,7 @@ struct client {
 	struct mail_storage_service_user *service_user;
 	const struct imap_settings *set;
 	const struct smtp_submit_settings *smtp_set;
-	string_t *capability_string;
+	struct imap_capability_list *capability_list;
 	const char *disconnect_reason;
 
         struct mail_user *user;
@@ -283,6 +283,9 @@ void client_disconnect_with_error(struct client *client,
    has an explicit capability, nothing is changed. */
 void client_add_capability(struct client *client, const char *capability);
 
+/* Generate the string of capabilities from the client */
+const char *client_get_capability(struct client *client);
+
 /* Send a line of data to client. */
 void client_send_line(struct client *client, const char *data);
 /* Send a line of data to client. Returns 1 if ok, 0 if buffer is getting full,

src/imap/main.c

@@ -194,19 +194,19 @@ client_add_input_capability(struct client *client, const unsigned char *client_i
 	if (input.tag == NULL) {
 		client_send_line(client, t_strconcat(
 			"* PREAUTH [CAPABILITY ",
-			str_c(client->capability_string), "] "
+			client_get_capability(client), "] "
 			"Logged in as ", client->user->username, NULL));
 	} else if (input.send_untagged_capability) {
 		/* client doesn't seem to understand tagged capabilities. send
 		   untagged instead and hope that it works. */
 		client_send_line(client, t_strconcat("* CAPABILITY ",
-			str_c(client->capability_string), NULL));
+			client_get_capability(client), NULL));
 		client_send_line(client,
 				 t_strconcat(input.tag, " OK Logged in", NULL));
 	} else {
 		client_send_line(client, t_strconcat(
 			input.tag, " OK [CAPABILITY ",
-			str_c(client->capability_string), "] Logged in", NULL));
+			client_get_capability(client), "] Logged in", NULL));
 	}
 	o_stream_uncork(output);
 	o_stream_unref(&output);