? 2008?11?13? 22:33, James Carlson ??:
> Huafeng Lu writes:
>> To support the IP instance information, and to support future changes,
>> we could change the API to use a TLV (type, length, value). We can put
>> all paramters in a structure like:
>> typedef cl_hook_param {
>> int cl_type;
>> size_t cl_len;
>> uint8_t cl_value[];
>> } cl_hook_param_t;
>> Thus, all future changes can be handled.
>
> Not sure how that'd work, but I suggest discussing the issue with the
> other folks involved in the project and then bringing the completed
> proposal back for ARC review.
>
> (My guess is that the 'types' defined effectively become part of the
> API itself, so the support for future changes given by that may be a
> little limited.)
Let me state it more clearly. The whole idea is illustrated below. We
first define the following:
typedef struct cl_hook_param {
int cl_type;
uint8_t cl_value[];
} cl_hook_param_t;
int (*cl_inet_connect2)(cl_hook_param_t *chp);
typedef struct cl_hook_conn_param {
int type;
netstackid_t stack_id;
uint8_t protocol;
boolean_t is_outgoing;
sa_family_t family;
uint8_t *laddrp;
in_port_t lport;
uint8_t *faddrp;
in_port_t fport;
} cl_hook_conn_param_t;
To call the hook, at Solaris side, we do:
cl_hook_conn_param_t hp;
hp.type = CL_HOOK_TYPE_CONN;
hp.stack_id = id;
hp.protocol = IPPROTO_TCP;
...
if ((err = cl_inet_connect2(&hp)) != 0)
...
At Cluster side, the hook implementation looks like:
int cl_inet_connect_impl(cl_hook_param_t *chp)
{
if (chp->cl_type == CL_HOOK_TYPE_CONN) {
//get all arguments from chp->cl_value
}
...
}
In the future, if we want to add or change some arguments, we only need
to change cl_hook_conn_param_t, while the hook signature will remain
unchanged.
One issue with this approach is that, all existing Solaris that calls
the hook need big code change - each needs to switch to the
cl_hook_xxx_param_t structure. An alternative is to keep all existing
arguments and the netstackid_t outside cl_hook_xxx_param_t, so that this
time all the hook only need to add a "NULL" argument.
Signature:
int (*cl_inet_connect2)(netstackid_t stack_id,
uint8_t protocol, boolean_t is_outgoing,
sa_family_t addr_family,
uint8_t *laddrp, in_port_t lport,
uint8_t *faddrp, in_port_t fport,
cl_hook_param_t *chp) = NULL;
How to call it for now (the last argument is NULL):
err = (*cl_inet_connect2)(id, IPPROTO_TCP, ..., fport, NULL);
In the future, when something changes, they can be put into
cl_hook_xxx_param_t and passed into the hook.
How do you think?
--
Huafeng
