| SYNOPSIS | 
#include <dkim.h>
DKIM_STAT dkim_set_key_lookup(
	DKIM_LIB *libopendkim,
        DKIM_CBSTAT (*func) (DKIM *dkim,
                             DKIM_SIGINFO *siginfo,
	                     unsigned char *buf,
	                     size_t buflen));
);
Defines a function which should do key lookups rather than implementing
the DKIM specification (e.g., a DNS lookup).  The query method specified
in the signature will be ignored. | 
|---|
| DESCRIPTION | 
| Called When | dkim_set_key_lookup() can be called at any time. |  | 
|---|
| ARGUMENTS | 
    | Argument | Description | 
|---|
 | libopendkim | Library-specific instance handle, returned by
        dkim_init(). |  | func | A pointer to a function which the library should use in place
	of its own code to do key lookups.  The function will receive
	four things: A DKIM handle
	referencing the job being processed, a pointer to a
	DKIM_SIGINFO handle
	identifying the signature whose public key should be retrieved,
	a pointer to a buffer that should receive the result of the key
	lookup, and the number of bytes available there.  The function should
	return an appropriate
	DKIM_CBSTAT return code after
	loading the buffer with its lookup result (if any).  If func
	is NULL, the internal key lookup implementation, which will do
	what the signature requests, will be used. |  | 
|---|
| RETURN VALUES |  | 
| NOTES | 
The callback should place into the provided buffer a NULL-terminated
    string formatted as a legal DKIM key record according to RFC6376
    Section 3.6.1.
 |