1 files changed, 118 insertions, 0 deletions
diff --git a/src/core/tsi/alts/frame_protector/alts_counter.cc b/src/core/tsi/alts/frame_protector/alts_counter.cc
new file mode 100644
index 0000000000..de163e3e08
--- /dev/null
+++ b/src/core/tsi/alts/frame_protector/alts_counter.cc
@@ -0,0 +1,118 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/tsi/alts/frame_protector/alts_counter.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+static void maybe_copy_error_msg(const char* src, char** dst) {
+  if (dst != nullptr && src != nullptr) {
+    *dst = static_cast<char*>(gpr_malloc(strlen(src) + 1));
+    memcpy(*dst, src, strlen(src) + 1);
+  }
+}
+
+grpc_status_code alts_counter_create(bool is_client, size_t counter_size,
+                                     size_t overflow_size,
+                                     alts_counter** crypter_counter,
+                                     char** error_details) {
+  /* Perform input sanity check. */
+  if (counter_size == 0) {
+    const char error_msg[] = "counter_size is invalid.";
+    maybe_copy_error_msg(error_msg, error_details);
+    return GRPC_STATUS_INVALID_ARGUMENT;
+  }
+  if (overflow_size == 0 || overflow_size >= counter_size) {
+    const char error_msg[] = "overflow_size is invalid.";
+    maybe_copy_error_msg(error_msg, error_details);
+    return GRPC_STATUS_INVALID_ARGUMENT;
+  }
+  if (crypter_counter == nullptr) {
+    const char error_msg[] = "crypter_counter is nullptr.";
+    maybe_copy_error_msg(error_msg, error_details);
+    return GRPC_STATUS_INVALID_ARGUMENT;
+  }
+  *crypter_counter =
+      static_cast<alts_counter*>(gpr_malloc(sizeof(**crypter_counter)));
+  (*crypter_counter)->size = counter_size;
+  (*crypter_counter)->overflow_size = overflow_size;
+  (*crypter_counter)->counter =
+      static_cast<unsigned char*>(gpr_zalloc(counter_size));
+  if (is_client) {
+    ((*crypter_counter)->counter)[counter_size - 1] = 0x80;
+  }
+  return GRPC_STATUS_OK;
+}
+
+grpc_status_code alts_counter_increment(alts_counter* crypter_counter,
+                                        bool* is_overflow,
+                                        char** error_details) {
+  /* Perform input sanity check. */
+  if (crypter_counter == nullptr) {
+    const char error_msg[] = "crypter_counter is nullptr.";
+    maybe_copy_error_msg(error_msg, error_details);
+    return GRPC_STATUS_INVALID_ARGUMENT;
+  }
+  if (is_overflow == nullptr) {
+    const char error_msg[] = "is_overflow is nullptr.";
+    maybe_copy_error_msg(error_msg, error_details);
+    return GRPC_STATUS_INVALID_ARGUMENT;
+  }
+  /* Increment the internal counter. */
+  size_t i = 0;
+  for (; i < crypter_counter->overflow_size; i++) {
+    (crypter_counter->counter)[i]++;
+    if ((crypter_counter->counter)[i] != 0x00) {
+      break;
+    }
+  }
+  /**
+   * If the lower overflow_size bytes are all zero, the counter has overflowed.
+   */
+  if (i == crypter_counter->overflow_size) {
+    *is_overflow = true;
+    return GRPC_STATUS_FAILED_PRECONDITION;
+  }
+  *is_overflow = false;
+  return GRPC_STATUS_OK;
+}
+
+size_t alts_counter_get_size(alts_counter* crypter_counter) {
+  if (crypter_counter == nullptr) {
+    return 0;
+  }
+  return crypter_counter->size;
+}
+
+unsigned char* alts_counter_get_counter(alts_counter* crypter_counter) {
+  if (crypter_counter == nullptr) {
+    return nullptr;
+  }
+  return crypter_counter->counter;
+}
+
+void alts_counter_destroy(alts_counter* crypter_counter) {
+  if (crypter_counter != nullptr) {
+    gpr_free(crypter_counter->counter);
+    gpr_free(crypter_counter);
+  }
+}