ISNS(3) | Library Functions Manual | ISNS(3) |
isns
—
#include <isns.h>
int
isns_init
(ISNS_HANDLE
*h, int
is_server);
void
isns_stop
(ISNS_HANDLE
h);
int
isns_add_servercon
(ISNS_HANDLE
h, int fd,
struct addrinfo *ai);
int
isns_init_reg_refresh
(ISNS_HANDLE
h, const char
*node, int
interval);
ISNS_TRANS
isns_new_trans
(ISNS_HANDLE
h, uint16_t
func_id, uint16_t
pdu_flags);
int
isns_add_tlv
(ISNS_TRANS
t, uint32_t tag,
int data_len,
const void *data_p);
int
isns_add_string
(ISNS_TRANS
t, uint32_t tag,
const char *s);
int
isns_send_trans
(ISNS_TRANS
t, const struct timespec
*timeout_p, uint32_t
*status_p);
int
isns_get_tlv
(ISNS_TRANS
t, int which_tlv,
uint32_t *tag_p,
int data_len_p,
void **data_pp);
void
isns_free_trans
(ISNS_TRANS
t);
isns
library exports an API that simplifies Internet
Storage Name Service (iSNS) client implementations. The API defines a
transactional model in support of:
isns
does not currently support receipt of
iSNS Heartbeat messages, State Change Notification (SCN) messages, or Entity
Status Inquiry (ESI) messages.
isns
must call
isns_init
() to initialize the iSNS environment. This
call will create a thread to handle client-server communication, and as such
should only be called when thread creation is appropriate (such as after a
daemonized program forks).
The value passed as is_server is used to set
iSNSP message format Flags "Sender is the iSNS client" (bit
position 16) and "Sender is the iSNS server" (bit position 17).
For now the value 0 (zero) should be passed for
is_server. The value returned in
h should be considered opaque by the caller. This
value is passed unchanged to isns_add_servercon
(),
isns_init_reg_refresh
(),
isns_stop
(), and
isns_new_trans
().
isns_stop
() should be called when the iSNS
environment is no longer needed. This call will kill any threads created by
isns_init
().
isns_add_servercon
() should be
used to make the iSNS environment aware of the iSNS server to which iSNSP
queries and requests are to be sent. This routine should not be called by a
program acting as an iSNS server.
A connected TCP socket descriptor is passed as parameter
fd. Parameter ai is the address
of the remote TCP endpoint. It is included so that reconnection may be
attempted by isns
in the event that the TCP
connection is broken.
Certain iSNS servers will limit registration lifetimes, and will
refresh registrations after any request from a given iSNS entity. The
isns_init_reg_refresh
() function offers a way for
isns
to refresh registrations on behalf of the iSNS
client.
Parameter node is the “iSCSI Name” attribute used for the periodic queries. It should be the name of an iSCSI node within the registered iSNS entity. The desired refresh interval, in seconds, is passed in parameter interval.
isns_new_trans
() creates new iSNS transactions.
Parameter func_id is used as the iSNSP message id. Parameter pdu_flags is used to set iSNSP message format Flags and is exposed to allow callers to set flag "Replace flag" (bit position 19). This provides callers with a way to specify whether a Device Attribute Registration Request is intended to update or replace an existing registration. This is currently the only use defined for parameter pdu_flags.
Once a new transaction has been created, callers can specify iSNS
attributes used for registration and query requests. TLV data may be added
using either isns_add_tlv
() or
isns_add_string
().
Parameter tag is the iSNS Tag corresponding
to the attribute being added. Parameter data_len is
the length of the attribute value. Parameter data_p
references the attribute value. The caller does not need to handle iSNS
attribute 4-byte alignment requirements. This is handled by the iSNS
environment on behalf of the caller.
isns_add_string
() may be used if the attribute value
is a NUL terminated C string.
Once a transaction has been populated with any required TLV data,
isns_send_trans
() can be used to submit an iSNSP
registration or query message.
Callers that submit iSNSP query messages may need to wait for
returned data. isns_send_trans
() supports bounded
waits. Successful waits, those that do not time out, return the iSNSP
response status code received in the iSNSP response message. If a wait does
time out, the value of status_p is undefined. Callers
that do not need to wait for returned data can simply pass
NULL
for parameter timeout_p.
Callers should set parameter status_p to
NULL
if not waiting.
isns_get_tlv
() is used to retrieve TLV
data returned in a transaction. The first call to
isns_get_tlv
() should pass the value
ISNS_TLV_FIRST
for parameter
which_tlv. Each subsequent TLV can be retrieved by
passing in ISNS_TLV_NEXT
in place of
ISNS_TLV_FIRST
.
When a caller is done with a transaction, having submitted either
a registration or a query message and retrieved any returned TLV data,
isns_free_trans
() should be used to release
resources used by the transaction.
isns_init
(),
isns_add_servercon
(),
isns_init_reg_refresh
(),
isns_add_tlv
(),
isns_add_string
(), and
isns_send_trans
() return 0 on success, or -1 on
failure. isns_new_trans
() returns 0 on success, or
ISNS_INVALID_TRANS
on failure.
isns_get_tlv
() returns 0 on success, or
ENOENT
if there are no TLVs to retrieve.
isns
first appeared in NetBSD
6.0. The isns
implementation was contributed to
the NetBSD Foundation by Wasabi Systems, Inc.
October 1, 2009 | NetBSD 9.0 |