ISC_SHA384_BLOCK_LENGTH
unsigned char key[ISC_SHA384_BLOCK_LENGTH];
isc_hmacsha384_init(hmacsha384ctx, hkey->key, ISC_SHA384_BLOCK_LENGTH);
if (r.length > ISC_SHA384_BLOCK_LENGTH) {
#define ISC_HMACSHA384_KEYLENGTH ISC_SHA384_BLOCK_LENGTH