Password sync plugin, and questions about plugin criticality

[Luke Howard]

Ken,

This looks fine to me in principle (although the initialization
should be able to return a value indicating failure).

That said, I don't mind the approach Netscape took with the SLAPI
plugin API for their directory server (Sun, OpenLDAP, IBM all use
the same interface). If we are looking for a plugin API we can
generalize to other interfaces and is extensible without breaking
ABI compatability, something similar might we worth looking into.

In this case it might look something like:

/* kapi-plugin.h */
typedef struct kapi_pblock Kapi_PBlock;
int kapi_pblock_get(Kapi_PBlock *, int, void *);
int kapi_pblock_set(Kapi_PBlock *, int, void *);

/* in plugin */
static int pwupdate_precommit_password(Kapi_PBlock *pb)
{
	krb5_data *password;
	krb5_data *error_msg;

	kapi_pblock_get(pb, KAPI_PWUPDATE_PASSWORD, &password);
	kapi_pblock_get(pb, KAPI_PWUPDATE_ERROR_MSG, &error_msg);
	...

	/*
	 * Non-zero on pre-op causes frontend to return, no
	 * further plugins are called
	 */
}

static int pwupdate_postcommit_password(Kapi_PBlock *pb)
{
	/* All post-op plugins get called regardless of return code */
}

int pwupdate_init(Kapi_PBlock *pb)
{
	void *context; /* per-plugin stuff */

	kapi_pblock_set(pb, KAPI_PLUGIN_PRE_PWUPDATE_FN, pwupdate_precommit_password);
	kapi_pblock_set(pb, KAPI_PLUGIN_POST_PWUPDATE_FN, pwupdate_postcommit_password);
	kapi_pblock_set(pb, KAPI_PLUGIN_CLOSE_FN, pwupdate_close);
	kapi_pblock_set(pb, KAPI_PLUGIN_PRIVATE, context);

	return 0; /* any other error will cause KDC not to start */
}

(The name of the initialization function would be specified in the
configuration.)

-- Luke

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