binder: RpcCertificateUtils -> RpcTlsUtils.

There will be key utils in this file as well.

Test: pass
Bug: 199344157
Change-Id: I1cc4c14a0663c0e9f0832a3bfad6cc9464a27e2d
diff --git a/libs/binder/RpcTlsUtils.cpp b/libs/binder/RpcTlsUtils.cpp
new file mode 100644
index 0000000..483cc7c
--- /dev/null
+++ b/libs/binder/RpcTlsUtils.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "RpcTlsUtils"
+#include <log/log.h>
+
+#include <binder/RpcTlsUtils.h>
+
+#include "Utils.h"
+
+namespace android {
+
+namespace {
+
+bssl::UniquePtr<X509> fromPem(const std::vector<uint8_t>& cert) {
+    if (cert.size() > std::numeric_limits<int>::max()) return nullptr;
+    bssl::UniquePtr<BIO> certBio(BIO_new_mem_buf(cert.data(), static_cast<int>(cert.size())));
+    return bssl::UniquePtr<X509>(PEM_read_bio_X509(certBio.get(), nullptr, nullptr, nullptr));
+}
+
+bssl::UniquePtr<X509> fromDer(const std::vector<uint8_t>& cert) {
+    if (cert.size() > std::numeric_limits<long>::max()) return nullptr;
+    const unsigned char* data = cert.data();
+    auto expectedEnd = data + cert.size();
+    bssl::UniquePtr<X509> ret(d2i_X509(nullptr, &data, static_cast<long>(cert.size())));
+    if (data != expectedEnd) {
+        ALOGE("%s: %td bytes remaining!", __PRETTY_FUNCTION__, expectedEnd - data);
+        return nullptr;
+    }
+    return ret;
+}
+
+} // namespace
+
+bssl::UniquePtr<X509> deserializeCertificate(const std::vector<uint8_t>& cert,
+                                             RpcCertificateFormat format) {
+    switch (format) {
+        case RpcCertificateFormat::PEM:
+            return fromPem(cert);
+        case RpcCertificateFormat::DER:
+            return fromDer(cert);
+    }
+    LOG_ALWAYS_FATAL("Unsupported format %d", static_cast<int>(format));
+}
+
+std::vector<uint8_t> serializeCertificate(X509* x509, RpcCertificateFormat format) {
+    bssl::UniquePtr<BIO> certBio(BIO_new(BIO_s_mem()));
+    switch (format) {
+        case RpcCertificateFormat::PEM: {
+            TEST_AND_RETURN({}, PEM_write_bio_X509(certBio.get(), x509));
+        } break;
+        case RpcCertificateFormat::DER: {
+            TEST_AND_RETURN({}, i2d_X509_bio(certBio.get(), x509));
+        } break;
+        default: {
+            LOG_ALWAYS_FATAL("Unsupported format %d", static_cast<int>(format));
+        }
+    }
+    const uint8_t* data;
+    size_t len;
+    TEST_AND_RETURN({}, BIO_mem_contents(certBio.get(), &data, &len));
+    return std::vector<uint8_t>(data, data + len);
+}
+
+} // namespace android