Implement decrypting inbound group messages

Includes creation of inbound sessions, etc

2 files changed, 58 insertions, 6 deletions

diff --git a/tests/test_group_session.cpp b/tests/test_group_session.cpp
index b9fe1ef..5bbdc9d 100644
--- a/tests/test_group_session.cpp
+++ b/tests/test_group_session.cpp
@@ -12,6 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+#include "olm/inbound_group_session.h"
 #include "olm/outbound_group_session.h"
 #include "unittest.hh"
 
@@ -19,11 +20,10 @@
 int main() {
 
 {
-
     TestCase test_case("Pickle outbound group");
 
     size_t size = olm_outbound_group_session_size();
-    void *memory = alloca(size);
+    uint8_t memory[size];
     OlmOutboundGroupSession *session = olm_outbound_group_session(memory);
 
     size_t pickle_length = olm_pickle_outbound_group_session_length(session);
@@ -61,9 +61,9 @@ int main() {
         "0123456789ABDEF0123456789ABCDEF";
 
 
-
+    /* build the outbound session */
     size_t size = olm_outbound_group_session_size();
-    void *memory = alloca(size);
+    uint8_t memory[size];
     OlmOutboundGroupSession *session = olm_outbound_group_session(memory);
 
     assert_equals((size_t)132,
@@ -73,18 +73,48 @@ int main() {
         session, random_bytes, sizeof(random_bytes));
     assert_equals((size_t)0, res);
 
+    assert_equals(0U, olm_outbound_group_session_message_index(session));
+    size_t session_key_len = olm_outbound_group_session_key_length(session);
+    uint8_t session_key[session_key_len];
+    olm_outbound_group_session_key(session, session_key, session_key_len);
+
+
+    /* encode the message */
     uint8_t plaintext[] = "Message";
     size_t plaintext_length = sizeof(plaintext) - 1;
 
     size_t msglen = olm_group_encrypt_message_length(
         session, plaintext_length);
 
-    uint8_t *msg = (uint8_t *)alloca(msglen);
+    uint8_t msg[msglen];
     res = olm_group_encrypt(session, plaintext, plaintext_length,
                             msg, msglen);
     assert_equals(msglen, res);
+    assert_equals(1U, olm_outbound_group_session_message_index(session));
+
+
+    /* build the inbound session */
+    size = olm_inbound_group_session_size();
+    uint8_t inbound_session_memory[size];
+    OlmInboundGroupSession *inbound_session =
+        olm_inbound_group_session(inbound_session_memory);
+
+    res = olm_init_inbound_group_session(
+        inbound_session, 0U, session_key, session_key_len);
+    assert_equals((size_t)0, res);
 
-    // TODO: decode the message
+    /* decode the message */
+
+    /* olm_group_decrypt_max_plaintext_length destroys the input so we have to
+       copy it. */
+    uint8_t msgcopy[msglen];
+    memcpy(msgcopy, msg, msglen);
+    size = olm_group_decrypt_max_plaintext_length(inbound_session, msgcopy, msglen);
+    uint8_t plaintext_buf[size];
+    res = olm_group_decrypt(inbound_session, msg, msglen,
+                            plaintext_buf, size);
+    assert_equals(plaintext_length, res);
+    assert_equals(plaintext, plaintext_buf, res);
 }
 
 }
diff --git a/tests/test_message.cpp b/tests/test_message.cpp
index e2385ea..5fec9e0 100644
--- a/tests/test_message.cpp
+++ b/tests/test_message.cpp
@@ -97,4 +97,26 @@ assert_equals(message2, output, 35);
     assert_equals(output+sizeof(expected)-1, ciphertext_ptr);
 } /* group message encode test */
 
+{
+    TestCase test_case("Group message decode test");
+
+    struct _OlmDecodeGroupMessageResults results;
+    std::uint8_t message[] =
+        "\x03"
+        "\x2A\x09sessionid"
+        "\x10\xc8\x01"
+        "\x22\x0A" "ciphertext"
+        "hmacsha2";
+
+    const uint8_t expected_session_id[] = "sessionid";
+
+    _olm_decode_group_message(message, sizeof(message)-1, 8, &results);
+    assert_equals(std::uint8_t(3), results.version);
+    assert_equals(std::size_t(9), results.session_id_length);
+    assert_equals(expected_session_id, results.session_id, 9);
+    assert_equals(1, results.has_chain_index);
+    assert_equals(std::uint32_t(200), results.chain_index);
+    assert_equals(std::size_t(10), results.ciphertext_length);
+    assert_equals(ciphertext, results.ciphertext, 10);
+} /* group message decode test */
 }