QUIC SRT GEN: Add SRT generator

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22599)

1 files changed, 83 insertions, 0 deletions

diff --git a/ssl/quic/quic_srt_gen.c b/ssl/quic/quic_srt_gen.c
new file mode 100644
index 0000000000..e43a55b29e
--- /dev/null
+++ b/ssl/quic/quic_srt_gen.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+#include "internal/quic_srt_gen.h"
+#include <openssl/core_names.h>
+#include <openssl/evp.h>
+
+struct quic_srt_gen_st {
+    EVP_MAC         *mac;
+    EVP_MAC_CTX     *mac_ctx;
+};
+
+/*
+ * Simple HMAC-SHA256-based stateless reset token generator.
+ */
+
+QUIC_SRT_GEN *ossl_quic_srt_gen_new(OSSL_LIB_CTX *libctx, const char *propq,
+                                    const unsigned char *key, size_t key_len)
+{
+    QUIC_SRT_GEN *srt_gen;
+    OSSL_PARAM params[3], *p = params;
+
+    if ((srt_gen = OPENSSL_zalloc(sizeof(*srt_gen))) == NULL)
+        return NULL;
+
+    if ((srt_gen->mac = EVP_MAC_fetch(libctx, "HMAC", propq)) == NULL)
+        goto err;
+
+    if ((srt_gen->mac_ctx = EVP_MAC_CTX_new(srt_gen->mac)) == NULL)
+        goto err;
+
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST, "SHA256", 7);
+    if (propq != NULL)
+        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_PROPERTIES,
+                                                (char *)propq, 0);
+    *p++ = OSSL_PARAM_construct_end();
+
+    if (!EVP_MAC_init(srt_gen->mac_ctx, key, key_len, params))
+        goto err;
+
+    return srt_gen;
+
+err:
+    ossl_quic_srt_gen_free(srt_gen);
+    return NULL;
+}
+
+void ossl_quic_srt_gen_free(QUIC_SRT_GEN *srt_gen)
+{
+    if (srt_gen == NULL)
+        return;
+
+    EVP_MAC_CTX_free(srt_gen->mac_ctx);
+    EVP_MAC_free(srt_gen->mac);
+    OPENSSL_free(srt_gen);
+}
+
+int ossl_quic_srt_gen_calculate_token(QUIC_SRT_GEN *srt_gen,
+                                      const QUIC_CONN_ID *dcid,
+                                      QUIC_STATELESS_RESET_TOKEN *token)
+{
+    size_t outl = 0;
+    unsigned char mac[32];
+
+    if (!EVP_MAC_init(srt_gen->mac_ctx, NULL, 0, NULL))
+        return 0;
+
+    if (!EVP_MAC_update(srt_gen->mac_ctx, (const unsigned char *)dcid->id,
+                        dcid->id_len))
+        return 0;
+
+    if (!EVP_MAC_final(srt_gen->mac_ctx, mac, &outl, sizeof(mac))
+        || outl != sizeof(mac))
+        return 0;
+
+    memcpy(token, mac, sizeof(*token));
+    return 1;
+}