1 files changed, 126 insertions, 0 deletions
diff --git a/include/olm/message.hh b/include/olm/message.hh
new file mode 100644
index 0000000..fefdd20
--- /dev/null
+++ b/include/olm/message.hh
@@ -0,0 +1,126 @@
+/* Copyright 2015 OpenMarket Ltd
+ *
+ * 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 <cstddef>
+#include <cstdint>
+
+
+namespace olm {
+
+/**
+ * The length of the buffer needed to hold a message.
+ */
+std::size_t encode_message_length(
+    std::uint32_t counter,
+    std::size_t ratchet_key_length,
+    std::size_t ciphertext_length,
+    std::size_t mac_length
+);
+
+
+struct MessageWriter {
+    std::uint8_t * ratchet_key;
+    std::uint8_t * ciphertext;
+};
+
+
+struct MessageReader {
+    std::uint8_t version;
+    bool has_counter;
+    std::uint32_t counter;
+    std::uint8_t const * input; std::size_t input_length;
+    std::uint8_t const * ratchet_key; std::size_t ratchet_key_length;
+    std::uint8_t const * ciphertext; std::size_t ciphertext_length;
+};
+
+
+/**
+ * Writes the message headers into the output buffer.
+ * Populates the writer struct with pointers into the output buffer.
+ */
+void encode_message(
+    MessageWriter & writer,
+    std::uint8_t version,
+    std::uint32_t counter,
+    std::size_t ratchet_key_length,
+    std::size_t ciphertext_length,
+    std::uint8_t * output
+);
+
+
+/**
+ * Reads the message headers from the input buffer.
+ * Populates the reader struct with pointers into the input buffer.
+ */
+void decode_message(
+    MessageReader & reader,
+    std::uint8_t const * input, std::size_t input_length,
+    std::size_t mac_length
+);
+
+
+struct PreKeyMessageWriter {
+    std::uint8_t * identity_key;
+    std::uint8_t * base_key;
+    std::uint8_t * message;
+};
+
+
+struct PreKeyMessageReader {
+    std::uint8_t version;
+    bool has_one_time_key_id;
+    std::uint32_t one_time_key_id;
+    std::uint8_t const * identity_key; std::size_t identity_key_length;
+    std::uint8_t const * base_key; std::size_t base_key_length;
+    std::uint8_t const * message; std::size_t message_length;
+};
+
+
+/**
+ * The length of the buffer needed to hold a message.
+ */
+std::size_t encode_one_time_key_message_length(
+    std::uint32_t one_time_key_id,
+    std::size_t identity_key_length,
+    std::size_t base_key_length,
+    std::size_t message_length
+);
+
+
+/**
+ * Writes the message headers into the output buffer.
+ * Populates the writer struct with pointers into the output buffer.
+ */
+void encode_one_time_key_message(
+    PreKeyMessageWriter & writer,
+    std::uint8_t version,
+    std::uint32_t one_time_key_id,
+    std::size_t identity_key_length,
+    std::size_t base_key_length,
+    std::size_t message_length,
+    std::uint8_t * output
+);
+
+
+/**
+ * Reads the message headers from the input buffer.
+ * Populates the reader struct with pointers into the input buffer.
+ */
+void decode_one_time_key_message(
+    PreKeyMessageReader & reader,
+    std::uint8_t const * input, std::size_t input_length
+);
+
+
+} // namespace olm