1 files changed, 86 insertions, 0 deletions
diff --git a/src/core/ext/census/trace_context.c b/src/core/ext/census/trace_context.c
new file mode 100644
index 0000000000..fbb20d3448
--- /dev/null
+++ b/src/core/ext/census/trace_context.c
@@ -0,0 +1,86 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/ext/census/trace_context.h"
+
+#include <grpc/census.h>
+#include <grpc/support/log.h>
+#include <stdbool.h>
+
+#include "third_party/nanopb/pb_decode.h"
+#include "third_party/nanopb/pb_encode.h"
+
+// This function assumes the TraceContext is valid.
+size_t encode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
+                            const size_t buf_size) {
+  // Create a stream that will write to our buffer.
+  pb_ostream_t stream = pb_ostream_from_buffer(buffer, buf_size);
+
+  // encode message
+  bool status = pb_encode(&stream, google_trace_TraceContext_fields, ctxt);
+
+  if (!status) {
+    gpr_log(GPR_DEBUG, "TraceContext encoding failed: %s",
+            PB_GET_ERROR(&stream));
+    return 0;
+  }
+
+  return stream.bytes_written;
+}
+
+bool decode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
+                          const size_t nbytes) {
+  // Create a stream that reads nbytes from the buffer.
+  pb_istream_t stream = pb_istream_from_buffer(buffer, nbytes);
+
+  // decode message
+  bool status = pb_decode(&stream, google_trace_TraceContext_fields, ctxt);
+
+  if (!status) {
+    gpr_log(GPR_DEBUG, "TraceContext decoding failed: %s",
+            PB_GET_ERROR(&stream));
+    return false;
+  }
+
+  // check fields
+  if (!ctxt->has_trace_id) {
+    gpr_log(GPR_DEBUG, "Invalid TraceContext: missing trace_id");
+    return false;
+  }
+  if (!ctxt->has_span_id) {
+    gpr_log(GPR_DEBUG, "Invalid TraceContext: missing span_id");
+    return false;
+  }
+
+  return true;
+}