Add support for iSCSI TargetAlias

This includes both support during iSCSI LOGIN and iSNS.

iscsi-scst/README

@@ -283,6 +283,10 @@ Each target subdirectory contains the following entries:
 
  - tid - TID of this target.
 
+ - alias - TargetAlias of this target.  If not set, it will default to the
+   empty string and no TargetAlias will be reported in LOGIN RESPONSE or iSNS
+   for this target.
+
 The "sessions" subdirectory contains the following attribute:
 
  - thread_pid - the process identifiers (PIDs) of the iscsird and iscsiwr
@@ -559,6 +563,7 @@ both iSCSI-SCST targets will look like:
 |       |   |-- NopInInterval
 |       |   |-- QueuedCommands
 |       |   |-- RspTimeout
+|       |   |-- alias
 |       |   |-- enabled
 |       |   |-- ini_groups
 |       |   |   `-- mgmt

iscsi-scst/usr/config.c

@@ -265,6 +265,32 @@ char *config_sep_string(char **pp)
 	return p;
 }
 
+/*
+ * Strip leading and trailing whitespace.
+ *
+ * Modifies the contents of the parameter string.
+ */
+char *config_strip_string(char *s)
+{
+	size_t size;
+	char *end;
+
+	size = strlen(s);
+
+	if (!size)
+		return s;
+
+	end = s + size - 1;
+	while (end >= s && isspace(*end))
+		end--;
+	*(end + 1) = '\0';
+
+	while (*s && isspace(*s))
+		s++;
+
+	return s;
+}
+
 static char *config_gets(char *buf, int size, const char *data, int *offset)
 {
 	int offs = *offset, i = 0;

iscsi-scst/usr/ctldev.c

@@ -78,7 +78,12 @@ int kernel_target_create(struct target *target, u32 *tid, u32 cookie)
 	info.tid = (tid != NULL) ? *tid : 0;
 	info.cookie = cookie;
 
-	info.attrs_num = 2;
+	/*
+	 * ISCSI_PER_PORTAL_ACL_ATTR_NAME
+	 * ISCSI_TARGET_REDIRECTION_ATTR_NAME
+	 * ISCSI_TARGET_ALIAS_ATTR_NAME
+	 */
+	info.attrs_num = 3;
 
 	for (j = 0; j < session_key_last; j++) {
 		if (session_keys[j].show_in_sysfs)
@@ -117,6 +122,11 @@ int kernel_target_create(struct target *target, u32 *tid, u32 cookie)
 		sizeof(ISCSI_TARGET_REDIRECTION_ATTR_NAME));
 	i++;
 
+	kern_attrs[i].mode = 0644;
+	strlcpy(kern_attrs[i].name, ISCSI_TARGET_ALIAS_ATTR_NAME,
+		sizeof(ISCSI_TARGET_ALIAS_ATTR_NAME));
+	i++;
+
 	for (j = 0; j < session_key_last; j++) {
 		if (!session_keys[j].show_in_sysfs)
 			continue;

iscsi-scst/usr/event.c

@@ -611,6 +611,17 @@ static int handle_e_get_attr_value(int fd, const struct iscsi_kern_event *event)
 			add_key_mark(res_str, sizeof(res_str), 0);
 		} else
 			*res_str = '\0';
+	} else if (strcasecmp(ISCSI_TARGET_ALIAS_ATTR_NAME, pp) == 0) {
+		if (target == NULL) {
+			log_error("Target expected for attr %s", pp);
+			res = -EINVAL;
+			goto out_free;
+		}
+		if (target->alias) {
+			snprintf(res_str, sizeof(res_str), "%s\n", target->alias);
+			add_key_mark(res_str, sizeof(res_str), 0);
+		} else
+			*res_str = '\0';
 	} else if (strcasecmp(ISCSI_ISNS_SERVER_ATTR_NAME, pp) == 0) {
 		if (target != NULL) {
 			log_error("Not NULL target %s for global attribute %s",
@@ -955,6 +966,48 @@ static int handle_e_set_attr_value(int fd, const struct iscsi_kern_event *event)
 		res = handle_target_redirect(target, p);
 		if (res != 0)
 			goto out_free;
+	} else if (strcasecmp(ISCSI_TARGET_ALIAS_ATTR_NAME, pp) == 0) {
+		bool alias_changed = false;
+
+		if (target == NULL) {
+			log_error("Target expected for attr %s", pp);
+			res = -EINVAL;
+			goto out_free;
+		}
+		p = config_strip_string(p);
+		if (*p == '\0') {
+			if (target->alias) {
+				free(target->alias);
+				target->alias = NULL;
+				alias_changed = true;
+			}
+		} else {
+			char *newval = strdup(p);
+
+			if (newval == NULL) {
+				log_error("Unable to duplicate alias name %s", p);
+				res = -ENOMEM;
+				goto out_free;
+			}
+			if (target->alias)
+				free(target->alias);
+			target->alias = newval;
+			alias_changed = true;
+		}
+		/* If we previously registered an alias and we need to update it */
+		if (alias_changed && target->isns_registered) {
+			if (target->alias) {
+				isns_target_register(target->name);
+			} else {
+				/*
+				 * We have cleared a previously set alias.
+				 * Work-around to make change visible in
+				 * open-isns server.
+				 */
+				isns_target_deregister(target->name);
+				isns_target_register(target->name);
+			}
+		}
 	} else if (strcasecmp(ISCSI_ISNS_SERVER_ATTR_NAME, pp) == 0) {
 		if (target != NULL) {
 			log_error("Not NULL target %s for global attribute %s",

iscsi-scst/usr/iscsid.c

@@ -921,6 +921,8 @@ static void login_start(struct connection *conn)
 				return;
 			}
 		}
+		if (target->alias)
+			text_key_add(conn, "TargetAlias", target->alias);
 		log_debug(1, "target %s, sessions_count %d", target_name,
 			target->sessions_count);
 	}

iscsi-scst/usr/iscsid.h

@@ -198,6 +198,7 @@ struct target {
 
 	unsigned int tgt_enabled:1;
 	unsigned int per_portal_acl:1;
+	unsigned int isns_registered:1;
 
 	unsigned int target_params[target_key_last];
 	unsigned int session_params[session_key_last];
@@ -353,6 +354,7 @@ extern int nl_open(void);
 
 /* config.c */
 extern char *config_sep_string(char **pp);
+extern char *config_strip_string(char *s);
 extern int config_parse_main(const char *data, u32 cookie);
 extern int config_load(const char *config_name);
 extern int config_target_create(u32 *tid, char *name);

iscsi-scst/usr/isns.c

@@ -482,7 +482,7 @@ int isns_target_register(char *name)
 	uint32_t port = htonl(server_port);
 	uint32_t node = htonl(ISNS_NODE_TARGET);
 	uint32_t type = htonl(2);
-	struct target *target;
+	struct target *target, *alias_target;
 	int err, initial = list_length_is_one(&targets_list);
 	int max_buf;
 
@@ -499,6 +499,7 @@ int isns_target_register(char *name)
 	tlv = (struct isns_tlv *)hdr->pdu;
 	max_buf = sizeof(buf) - offsetof(struct isns_hdr, pdu);
 
+	alias_target = target_find_by_name(name);
 	if (strlen(isns_entity_target_name) < 1) {
 		target = list_entry(targets_list.q_forw, struct target, tlist);
 		err = isns_tlv_set(&tlv, max_buf - length, ISNS_ATTR_ISCSI_NAME,
@@ -566,6 +567,14 @@ int isns_target_register(char *name)
 		goto out;
 	length += err;
 
+	if (alias_target && alias_target->alias) {
+		err = isns_tlv_set(&tlv, max_buf - length, ISNS_ATTR_ISCSI_ALIAS,
+					strlen(alias_target->alias) + 1, alias_target->alias);
+		if (err < 0)
+			goto out;
+		length += err;
+	}
+
 	err = isns_tlv_set(&tlv, max_buf - length, ISNS_ATTR_ISCSI_NODE_TYPE,
 				sizeof(node), &node);
 	if (err < 0)
@@ -579,6 +588,8 @@ int isns_target_register(char *name)
 	err = write(isns_fd, buf, length + sizeof(struct isns_hdr));
 	if (err < 0)
 		log_error("%s %d: %s", __func__, __LINE__, strerror(errno));
+	else if (alias_target)
+		alias_target->isns_registered = 1;
 
 	if (scn_listen_port)
 		isns_scn_register();
@@ -662,6 +673,9 @@ int isns_target_deregister(char *name)
 	if (err < 0)
 		log_error("%s %d: %s", __func__, __LINE__, strerror(errno));
 
+	if (target)
+		target->isns_registered = 0;
+
 out:
 	return err;
 }

iscsi-scst/usr/param.h

@@ -25,6 +25,7 @@
 #define ISCSI_TARGET_REDIRECTION_ATTR_NAME	"redirect"
 #define ISCSI_TARGET_REDIRECTION_VALUE_TEMP	"temp"
 #define ISCSI_TARGET_REDIRECTION_VALUE_PERM	"perm"
+#define ISCSI_TARGET_ALIAS_ATTR_NAME		"alias"
 
 struct iscsi_key;