Implement pickling/unpickling for outbound group sessions

2 files changed, 51 insertions, 0 deletions

diff --git a/include/olm/megolm.h b/include/olm/megolm.h
index 5cae353..831c6fb 100644
--- a/include/olm/megolm.h
+++ b/include/olm/megolm.h
@@ -61,6 +61,21 @@ const struct _olm_cipher *megolm_cipher();
  */
 void megolm_init(Megolm *megolm, uint8_t const *random_data, uint32_t counter);
 
+/** Returns the number of bytes needed to store a megolm */
+size_t megolm_pickle_length(const Megolm *megolm);
+
+/**
+ * Pickle the megolm. Returns a pointer to the next free space in the buffer.
+ */
+uint8_t * megolm_pickle(const Megolm *megolm, uint8_t *pos);
+
+/**
+ * Unpickle the megolm. Returns a pointer to the next item in the buffer.
+ */
+const uint8_t * megolm_unpickle(Megolm *megolm, const uint8_t *pos,
+                                const uint8_t *end);
+
+
 /** advance the ratchet by one step */
 void megolm_advance(Megolm *megolm);
 
diff --git a/include/olm/outbound_group_session.h b/include/olm/outbound_group_session.h
index 6c02370..27991ac 100644
--- a/include/olm/outbound_group_session.h
+++ b/include/olm/outbound_group_session.h
@@ -48,6 +48,42 @@ size_t olm_clear_outbound_group_session(
     OlmOutboundGroupSession *session
 );
 
+/** Returns the number of bytes needed to store an outbound group session */
+size_t olm_pickle_outbound_group_session_length(
+    const OlmOutboundGroupSession *session
+);
+
+/**
+ * Stores a group session as a base64 string. Encrypts the session using the
+ * supplied key. Returns the length of the session on success.
+ *
+ * Returns olm_error() on failure. If the pickle output buffer
+ * is smaller than olm_pickle_outbound_group_session_length() then
+ * olm_outbound_group_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL"
+ */
+size_t olm_pickle_outbound_group_session(
+    OlmOutboundGroupSession *session,
+    void const * key, size_t key_length,
+    void * pickled, size_t pickled_length
+);
+
+/**
+ * Loads a group session from a pickled base64 string. Decrypts the session
+ * using the supplied key.
+ *
+ * Returns olm_error() on failure. If the key doesn't match the one used to
+ * encrypt the account then olm_outbound_group_session_last_error() will be
+ * "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then
+ * olm_outbound_group_session_last_error() will be "INVALID_BASE64". The input
+ * pickled buffer is destroyed
+ */
+size_t olm_unpickle_outbound_group_session(
+    OlmOutboundGroupSession *session,
+    void const * key, size_t key_length,
+    void * pickled, size_t pickled_length
+);
+
+
 /** The number of random bytes needed to create an outbound group session */
 size_t olm_init_outbound_group_session_random_length(
     const OlmOutboundGroupSession *session