Merge branch 'dbkr/olm_session_describe' into 'master'

Add olm_session_describe

See merge request matrix-org/olm!9

5 files changed, 69 insertions, 0 deletions

diff --git a/include/olm/olm.h b/include/olm/olm.h
index 61ea07b..6a2b3fb 100644
--- a/include/olm/olm.h
+++ b/include/olm/olm.h
@@ -318,6 +318,12 @@ int olm_session_has_received_message(
     OlmSession *session
 );
 
+/**
+ * Write a null-terminated string describing the internal state of an olm
+ * session to the buffer provided for debugging and logging purposes.
+ */
+void olm_session_describe(OlmSession * session, char *buf, size_t buflen);
+
 /** Checks if the PRE_KEY message is for this in-bound session. This can happen
  * if multiple messages are sent to this account before this account sends a
  * message in reply. The one_time_key_message buffer is destroyed. Returns 1 if
diff --git a/include/olm/session.hh b/include/olm/session.hh
index 9d44816..ce05fc8 100644
--- a/include/olm/session.hh
+++ b/include/olm/session.hh
@@ -131,6 +131,14 @@ struct Session {
         std::uint8_t const * message, std::size_t message_length,
         std::uint8_t * plaintext, std::size_t max_plaintext_length
     );
+
+    /**
+     * Write a string describing this session and its state (not including the
+     * private key) into the buffer provided.
+     *
+     * Takes a buffer to write to and the length of that buffer
+     */
+    void describe(char *buf, size_t buflen);
 };
 
 
diff --git a/javascript/olm_post.js b/javascript/olm_post.js
index ad058d9..e204f30 100644
--- a/javascript/olm_post.js
+++ b/javascript/olm_post.js
@@ -459,6 +459,19 @@ Session.prototype['decrypt'] = restore_stack(function(
 
 });
 
+Session.prototype['describe'] = restore_stack(function() {
+    var description_buf;
+    try {
+        description_buf = malloc(256);
+        session_method(Module['_olm_session_describe'])(
+            this.ptr, description_buf, 256
+        );
+        return UTF8ToString(description_buf);
+    } finally {
+        if (description_buf !== undefined) free(description_buf);
+    }
+});
+
 function Utility() {
     var size = Module['_olm_utility_size']();
     this.buf = malloc(size);
diff --git a/src/olm.cpp b/src/olm.cpp
index d626c84..0333b10 100644
--- a/src/olm.cpp
+++ b/src/olm.cpp
@@ -535,6 +535,12 @@ int olm_session_has_received_message(
     return from_c(session)->received_message;
 }
 
+void olm_session_describe(
+    OlmSession * session, char *buf, size_t buflen
+) {
+    from_c(session)->describe(buf, buflen);
+}
+
 size_t olm_matches_inbound_session(
     OlmSession * session,
     void * one_time_key_message, size_t message_length
diff --git a/src/session.cpp b/src/session.cpp
index f1bc5a7..b619e56 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -21,6 +21,7 @@
 #include "olm/pickle.hh"
 
 #include <cstring>
+#include <stdio.h>
 
 namespace {
 
@@ -397,6 +398,41 @@ std::size_t olm::Session::decrypt(
     return result;
 }
 
+void olm::Session::describe(char *describe_buffer, size_t buflen) {
+    if (buflen == 0) return;
+
+    describe_buffer[0] = '\0';
+    char *buf_pos = describe_buffer;
+
+    int size;
+
+    size = snprintf(
+        buf_pos, buflen - (buf_pos - describe_buffer),
+        "sender chain index: %d ", ratchet.sender_chain[0].chain_key.index
+    );
+    if (size > 0) buf_pos += size;
+
+    size = snprintf(buf_pos, buflen - (buf_pos - describe_buffer), "receiver chain indices:");
+    if (size > 0) buf_pos += size;
+    for (size_t i = 0; i < ratchet.receiver_chains.size(); ++i) {
+        size = snprintf(
+            buf_pos, buflen - (buf_pos - describe_buffer),
+            " %d", ratchet.receiver_chains[i].chain_key.index
+        );
+        if (size > 0) buf_pos += size;
+    }
+
+    size = snprintf(buf_pos, buflen - (buf_pos - describe_buffer), " skipped message keys:");
+    if (size >= 0) buf_pos += size;
+    for (size_t i = 0; i < ratchet.skipped_message_keys.size(); ++i) {
+        size = snprintf(
+            buf_pos, buflen - (buf_pos - describe_buffer),
+            " %d", ratchet.skipped_message_keys[i].message_key.index
+        );
+        if (size > 0) buf_pos += size;
+    }
+}
+
 namespace {
 // the master branch writes pickle version 1; the logging_enabled branch writes
 // 0x80000001.