doc/developer-guide/api/functions/TSHttpTxnCacheKeyDigestGet.en.rst

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   License, Version 2.0 (the "License"); you may not use this file
   except in compliance with the License.  You may obtain a copy of
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   http://www.apache.org/licenses/LICENSE-2.0

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.. include:: ../../../common.defs

.. default-domain:: cpp

TSHttpTxnCacheKeyDigestGet
**************************

Synopsis
========

.. code-block:: cpp

    #include <ts/ts.h>

.. function:: TSReturnCode TSHttpTxnCacheKeyDigestGet(TSHttpTxn txnp, char *buffer, int *length)

Description
===========

Get the effective cache key digest (cryptographic hash) that was used for
cache lookup or storage on this transaction. This is the raw hash bytes,
not a hex or base64 encoding.

The digest size depends on the build configuration: 16 bytes for MD5
(default) or 32 bytes for SHA-256 (FIPS mode). A 32-byte buffer is
sufficient for either mode:

.. code-block:: c

    char digest[32];
    int  digest_len = sizeof(digest);
    if (TSHttpTxnCacheKeyDigestGet(txnp, digest, &digest_len) == TS_SUCCESS) {
      // digest_len contains the actual number of bytes written
    }

Pass :code:`nullptr` for *buffer* to query the digest size without
copying.

Returns :enumerator:`TS_SUCCESS` if a cache key was computed for the
transaction. Returns :enumerator:`TS_ERROR` if no cache lookup was
performed, or if *buffer* is non-null and *\*length* is smaller than the
digest size. In all cases *\*length* is set to the required digest size
on return.

See Also
========

:func:`TSHttpTxnCacheLookupUrlGet`