fips-prf: Fail when trying to use append mode on FIPS-PRF

Append mode hardly makes sense for the special stateful FIPS-PRF, which is
different to other PRFs.

diff --git a/src/libstrongswan/plugins/fips_prf/fips_prf.c b/src/libstrongswan/plugins/fips_prf/fips_prf.c
index 23825078e6f2a161b5386239ff4837cc7e23b2ca..25accf996f074c33248c233b7d0f1e22ae2db1bc 100644 (file)
--- a/src/libstrongswan/plugins/fips_prf/fips_prf.c
+++ b/src/libstrongswan/plugins/fips_prf/fips_prf.c
@@ -116,6 +116,12 @@ METHOD(prf_t, get_bytes, bool,
        u_int8_t *xkey = this->key;
        u_int8_t one[this->b];
 
+       if (!w)
+       {
+               /* append mode is not supported */
+               return FALSE;
+       }
+
        memset(one, 0, this->b);
        one[this->b - 1] = 0x01;
 
@@ -250,4 +256,3 @@ fips_prf_t *fips_prf_create(pseudo_random_function_t algo)
 
        return &this->public;
 }
-