openssl: Add support for new API to squeeze data from XOFs

This new API doesn't require a temporary buffer and generating a lot
of already consumed output.

diff --git a/src/libstrongswan/plugins/openssl/openssl_xof.c b/src/libstrongswan/plugins/openssl/openssl_xof.c
index 84d6bb7cb90352983443832ffe20b910448490ab..3b12c6fee88ef80f57c31fcc625d4dab72fe2abc 100644 (file)
--- a/src/libstrongswan/plugins/openssl/openssl_xof.c
+++ b/src/libstrongswan/plugins/openssl/openssl_xof.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2020 Tobias Brunner
+ * Copyright (C) 2020-2023 Tobias Brunner
  *
  * Copyright (C) secunet Security Networks AG
  *
@@ -50,6 +50,7 @@ struct private_xof_t {
         */
        EVP_MD_CTX *ctx;
 
+#if OPENSSL_VERSION_NUMBER < 0x30300000L
        /**
         * Current seed
         */
@@ -59,6 +60,7 @@ struct private_xof_t {
         * Offset into generated data
         */
        size_t offset;
+#endif
 };
 
 METHOD(xof_t, get_type, ext_out_function_t,
@@ -67,17 +69,33 @@ METHOD(xof_t, get_type, ext_out_function_t,
        return this->algorithm;
 }
 
+/**
+ * Initialize the EVP_MD_CTX with the given seed
+ */
+static bool init_md(private_xof_t *this, chunk_t seed)
+{
+       return EVP_DigestInit_ex(this->ctx, this->md, NULL) == 1 &&
+                  EVP_DigestUpdate(this->ctx, seed.ptr, seed.len) == 1;
+}
+
 METHOD(xof_t, get_bytes, bool,
        private_xof_t *this, size_t out_len, uint8_t *buffer)
 {
        bool success = FALSE;
-       chunk_t data;
 
+#if OPENSSL_VERSION_NUMBER >= 0x30300000L
+       /* this API is available since 3.2.0 */
+       if (EVP_DigestSqueeze(this->ctx, buffer, out_len) == 1)
+       {
+               success = TRUE;
+       }
+#else /* OPENSSL_VERSION_NUMBER */
        /* we can call EVP_DigestFinalXOF() only once, so to support an arbitrary
         * number of calls to get_bytes(), we request all the data we already
         * requested previously and just ignore what we already handed out */
-       if (EVP_DigestInit_ex(this->ctx, this->md, NULL) == 1 &&
-               EVP_DigestUpdate(this->ctx, this->seed.ptr, this->seed.len) == 1)
+       chunk_t data;
+
+       if (init_md(this, this->seed))
        {
                data = chunk_alloc(out_len + this->offset);
                if (EVP_DigestFinalXOF(this->ctx, data.ptr, data.len) == 1)
@@ -88,6 +106,7 @@ METHOD(xof_t, get_bytes, bool,
                }
                chunk_clear(&data);
        }
+#endif /* OPENSSL_VERSION_NUMBER */
        return success;
 }
 
@@ -113,17 +132,23 @@ METHOD(xof_t, get_seed_size, size_t,
 METHOD(xof_t, set_seed, bool,
        private_xof_t *this, chunk_t seed)
 {
+#if OPENSSL_VERSION_NUMBER >= 0x30300000L
+       return init_md(this, seed);
+#else
        chunk_clear(&this->seed);
        this->seed = chunk_clone(seed);
        this->offset = 0;
        return TRUE;
+#endif
 }
 
 METHOD(xof_t, destroy, void,
        private_xof_t *this)
 {
-       EVP_MD_CTX_free(this->ctx);
+#if OPENSSL_VERSION_NUMBER < 0x30300000L
        chunk_clear(&this->seed);
+#endif
+       EVP_MD_CTX_free(this->ctx);
        free(this);
 }