Allow OSSL_PARAM_get_octet_string() to pass a NULL buffer

We may just want to know the number of octets so allow passing a NULL
buffer.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11635)

diff --git a/crypto/params.c b/crypto/params.c
index 32161d0533884c34cc4cf55702fc4ac96cb8dc9b..06ae1bc44f37b98276c6a87063b80c41391a4ca0 100644 (file)
--- a/crypto/params.c
+++ b/crypto/params.c
@@ -780,7 +780,7 @@ static int get_string_internal(const OSSL_PARAM *p, void **val, size_t max_len,
 {
     size_t sz;
 
-    if (val == NULL || p == NULL || p->data_type != type)
+    if ((val == NULL && used_len == NULL) || p == NULL || p->data_type != type)
         return 0;
 
     sz = p->data_size;
@@ -793,6 +793,9 @@ static int get_string_internal(const OSSL_PARAM *p, void **val, size_t max_len,
     if (p->data == NULL)
         return 0;
 
+    if (val == NULL)
+        return 1;
+
     if (*val == NULL) {
         char *const q = OPENSSL_malloc(sz);
 

diff --git a/doc/man3/OSSL_PARAM_int.pod b/doc/man3/OSSL_PARAM_int.pod
index 9126906883a9dac3f32b8eee5f34b9d3e0bc36ef..09215184a7513d4a58ef7b7891b8e38769de7e6e 100644 (file)
--- a/doc/man3/OSSL_PARAM_int.pod
+++ b/doc/man3/OSSL_PARAM_int.pod
@@ -233,7 +233,9 @@ OSSL_PARAM_get_octet_string() retrieves an OCTET string from the parameter
 pointed to by B<p>.
 The OCTETs are either stored into B<*val> with a length limit of B<max_len> or,
 in the case when B<*val> is B<NULL>, memory is allocated and
-B<max_len> is ignored.
+B<max_len> is ignored. B<*used_len> is populated with the number of OCTETs
+stored. If B<val> is NULL then the OCTETS are not stored, but B<*used_len> is
+still populated.
 If memory is allocated by this function, it must be freed by the caller.
 
 OSSL_PARAM_set_octet_string() sets an OCTET string from the parameter