1 files changed, 346 insertions, 77 deletions

diff --git a/src/messenger/messenger_api_message.c b/src/messenger/messenger_api_message.c
index fdab60eef..d88859186 100644
--- a/src/messenger/messenger_api_message.c
+++ b/src/messenger/messenger_api_message.c
@@ -1,6 +1,6 @@
 /*
    This file is part of GNUnet.
-   Copyright (C) 2020 GNUnet e.V.
+   Copyright (C) 2020--2021 GNUnet e.V.
 
    GNUnet is free software: you can redistribute it and/or modify it
    under the terms of the GNU Affero General Public License as published
@@ -69,6 +69,8 @@ create_message (enum GNUNET_MESSENGER_MessageKind kind)
 struct GNUNET_MESSENGER_Message*
 copy_message (const struct GNUNET_MESSENGER_Message *message)
 {
+  GNUNET_assert(message);
+
   struct GNUNET_MESSENGER_Message *copy = GNUNET_new(struct GNUNET_MESSENGER_Message);
 
   GNUNET_memcpy(copy, message, sizeof(struct GNUNET_MESSENGER_Message));
@@ -125,11 +127,28 @@ destroy_message_body (enum GNUNET_MESSENGER_MessageKind kind, struct GNUNET_MESS
 void
 destroy_message (struct GNUNET_MESSENGER_Message *message)
 {
+  GNUNET_assert(message);
+
   destroy_message_body (message->header.kind, &(message->body));
 
   GNUNET_free(message);
 }
 
+int
+is_message_session_bound (const struct GNUNET_MESSENGER_Message *message)
+{
+  GNUNET_assert(message);
+
+  if ((GNUNET_MESSENGER_KIND_JOIN == message->header.kind) ||
+      (GNUNET_MESSENGER_KIND_LEAVE == message->header.kind) ||
+      (GNUNET_MESSENGER_KIND_NAME == message->header.kind) ||
+      (GNUNET_MESSENGER_KIND_KEY == message->header.kind) ||
+      (GNUNET_MESSENGER_KIND_ID == message->header.kind))
+    return GNUNET_YES;
+  else
+    return GNUNET_NO;
+}
+
 static void
 fold_short_message (const struct GNUNET_MESSENGER_Message *message, struct GNUNET_MESSENGER_ShortMessage *shortened)
 {
@@ -158,18 +177,7 @@ get_message_body_kind_size (enum GNUNET_MESSENGER_MessageKind kind)
   switch (kind)
   {
   case GNUNET_MESSENGER_KIND_INFO:
-    length += member_size(struct GNUNET_MESSENGER_Message, body.info.host_key);
-    length += member_size(struct GNUNET_MESSENGER_Message, body.info.unique_id);
-    break;
-  case GNUNET_MESSENGER_KIND_JOIN:
-    length += member_size(struct GNUNET_MESSENGER_Message, body.join.key);
-    break;
-  case GNUNET_MESSENGER_KIND_LEAVE:
-    break;
-  case GNUNET_MESSENGER_KIND_NAME:
-    break;
-  case GNUNET_MESSENGER_KIND_KEY:
-    length += member_size(struct GNUNET_MESSENGER_Message, body.key.key);
+    length += member_size(struct GNUNET_MESSENGER_Message, body.info.messenger_version);
     break;
   case GNUNET_MESSENGER_KIND_PEER:
     length += member_size(struct GNUNET_MESSENGER_Message, body.peer.peer);
@@ -195,7 +203,7 @@ get_message_body_kind_size (enum GNUNET_MESSENGER_MessageKind kind)
   case GNUNET_MESSENGER_KIND_FILE:
     length += member_size(struct GNUNET_MESSENGER_Message, body.file.key);
     length += member_size(struct GNUNET_MESSENGER_Message, body.file.hash);
-    length += NAME_MAX;
+    length += member_size(struct GNUNET_MESSENGER_Message, body.file.name);
     break;
   case GNUNET_MESSENGER_KIND_PRIVATE:
     length += member_size(struct GNUNET_MESSENGER_Message, body.private.key);
@@ -207,16 +215,17 @@ get_message_body_kind_size (enum GNUNET_MESSENGER_MessageKind kind)
   return length;
 }
 
+typedef uint32_t kind_t;
+
 uint16_t
 get_message_kind_size (enum GNUNET_MESSENGER_MessageKind kind)
 {
   uint16_t length = 0;
 
-  length += member_size(struct GNUNET_MESSENGER_Message, header.signature);
   length += member_size(struct GNUNET_MESSENGER_Message, header.timestamp);
   length += member_size(struct GNUNET_MESSENGER_Message, header.sender_id);
   length += member_size(struct GNUNET_MESSENGER_Message, header.previous);
-  length += member_size(struct GNUNET_MESSENGER_Message, header.kind);
+  length += sizeof(kind_t);
 
   return length + get_message_body_kind_size (kind);
 }
@@ -228,8 +237,17 @@ get_message_body_size (enum GNUNET_MESSENGER_MessageKind kind, const struct GNUN
 
   switch (kind)
   {
+  case GNUNET_MESSENGER_KIND_INFO:
+    length += GNUNET_IDENTITY_key_get_length(&(body->info.host_key));
+    break;
+  case GNUNET_MESSENGER_KIND_JOIN:
+    length += GNUNET_IDENTITY_key_get_length(&(body->join.key));
+    break;
   case GNUNET_MESSENGER_KIND_NAME:
-    length += (body->name.name? strlen (body->name.name) : 0);
+    length += (body->name.name ? strlen (body->name.name) : 0);
+    break;
+  case GNUNET_MESSENGER_KIND_KEY:
+    length += GNUNET_IDENTITY_key_get_length(&(body->key.key));
     break;
   case GNUNET_MESSENGER_KIND_TEXT:
     length += strlen (body->text.text);
@@ -248,19 +266,76 @@ get_message_body_size (enum GNUNET_MESSENGER_MessageKind kind, const struct GNUN
 }
 
 uint16_t
-get_message_size (const struct GNUNET_MESSENGER_Message *message)
+get_message_size (const struct GNUNET_MESSENGER_Message *message,
+                  int include_signature)
 {
-  return get_message_kind_size (message->header.kind) + get_message_body_size (message->header.kind, &(message->body));
+  GNUNET_assert(message);
+
+  uint16_t length = 0;
+
+  if (GNUNET_YES == include_signature)
+    length += GNUNET_IDENTITY_signature_get_length(&(message->header.signature));
+
+  length += get_message_kind_size (message->header.kind);
+  length += get_message_body_size (message->header.kind, &(message->body));
+
+  return length;
 }
 
 static uint16_t
-get_short_message_size (const struct GNUNET_MESSENGER_ShortMessage *message)
+get_short_message_size (const struct GNUNET_MESSENGER_ShortMessage *message, int include_body)
 {
+  const uint16_t minimum_size = sizeof(struct GNUNET_HashCode) + sizeof(kind_t);
+
   if (message)
-    return sizeof(message->kind) + get_message_body_kind_size (message->kind)
-           + get_message_body_size (message->kind, &(message->body));
+    return minimum_size + get_message_body_kind_size (message->kind)
+           + (include_body == GNUNET_YES? get_message_body_size (message->kind, &(message->body)) : 0);
   else
-    return sizeof(message->kind);
+    return minimum_size;
+}
+
+static uint16_t
+calc_usual_padding ()
+{
+  uint16_t padding = 0;
+  uint16_t kind_size;
+
+  for (int i = 0; i <= GNUNET_MESSENGER_KIND_MAX; i++) {
+    kind_size = get_message_kind_size ((enum GNUNET_MESSENGER_MessageKind) i);
+
+    if (kind_size > padding)
+      padding = kind_size;
+  }
+
+  return padding + GNUNET_MESSENGER_PADDING_MIN;
+}
+
+#define max(x, y) (x > y? x : y)
+
+static uint16_t
+calc_padded_length (uint16_t length)
+{
+  static uint16_t usual_padding = 0;
+
+  if (!usual_padding)
+    usual_padding = calc_usual_padding();
+
+  const uint16_t padded_length = max(
+      length + GNUNET_MESSENGER_PADDING_MIN,
+      usual_padding
+  );
+
+  if (padded_length <= GNUNET_MESSENGER_PADDING_LEVEL0)
+    return GNUNET_MESSENGER_PADDING_LEVEL0;
+
+  if (padded_length <= GNUNET_MESSENGER_PADDING_LEVEL1)
+    return GNUNET_MESSENGER_PADDING_LEVEL1;
+
+  if (padded_length <= GNUNET_MESSENGER_PADDING_LEVEL2)
+    return GNUNET_MESSENGER_PADDING_LEVEL2;
+
+  return GNUNET_MESSENGER_MAX_MESSAGE_SIZE;
+
 }
 
 #define min(x, y) (x < y? x : y)
@@ -272,7 +347,27 @@ get_short_message_size (const struct GNUNET_MESSENGER_ShortMessage *message)
 
 #define encode_step(dst, offset, src) do {         \
   encode_step_ext(dst, offset, src, sizeof(*src)); \
-} while(0)
+} while (0)
+
+#define encode_step_key(dst, offset, src, length) do {  \
+  ssize_t result = GNUNET_IDENTITY_write_key_to_buffer( \
+      src, dst + offset, length - offset                \
+  );                                                    \
+  if (result < 0)                                       \
+    GNUNET_break (0);                                   \
+  else                                                  \
+    offset += result;                                   \
+} while (0)
+
+#define encode_step_signature(dst, offset, src, length) do {  \
+  ssize_t result = GNUNET_IDENTITY_write_signature_to_buffer( \
+      src, dst + offset, length - offset                      \
+  );                                                          \
+  if (result < 0)                                             \
+    GNUNET_break (0);                                         \
+  else                                                        \
+    offset += result;                                         \
+} while (0)
 
 static void
 encode_message_body (enum GNUNET_MESSENGER_MessageKind kind, const struct GNUNET_MESSENGER_MessageBody *body,
@@ -281,20 +376,18 @@ encode_message_body (enum GNUNET_MESSENGER_MessageKind kind, const struct GNUNET
   switch (kind)
   {
   case GNUNET_MESSENGER_KIND_INFO:
-    encode_step(buffer, offset, &(body->info.host_key));
-    encode_step(buffer, offset, &(body->info.unique_id));
+    encode_step_key(buffer, offset, &(body->info.host_key), length);
+    encode_step(buffer, offset, &(body->info.messenger_version));
     break;
   case GNUNET_MESSENGER_KIND_JOIN:
-    encode_step(buffer, offset, &(body->join.key));
-    break;
-  case GNUNET_MESSENGER_KIND_LEAVE:
+    encode_step_key(buffer, offset, &(body->join.key), length);
     break;
   case GNUNET_MESSENGER_KIND_NAME:
     if (body->name.name)
       encode_step_ext(buffer, offset, body->name.name, min(length - offset, strlen(body->name.name)));
     break;
   case GNUNET_MESSENGER_KIND_KEY:
-    encode_step(buffer, offset, &(body->key.key));
+    encode_step_key(buffer, offset, &(body->key.key), length);
     break;
   case GNUNET_MESSENGER_KIND_PEER:
     encode_step(buffer, offset, &(body->peer.peer));
@@ -321,7 +414,7 @@ encode_message_body (enum GNUNET_MESSENGER_MessageKind kind, const struct GNUNET
   case GNUNET_MESSENGER_KIND_FILE:
     encode_step(buffer, offset, &(body->file.key));
     encode_step(buffer, offset, &(body->file.hash));
-    encode_step_ext(buffer, offset, body->file.name, NAME_MAX);
+    encode_step_ext(buffer, offset, body->file.name, sizeof(body->file.name));
     encode_step_ext(buffer, offset, body->file.uri, min(length - offset, strlen(body->file.uri)));
     break;
   case GNUNET_MESSENGER_KIND_PRIVATE:
@@ -331,18 +424,40 @@ encode_message_body (enum GNUNET_MESSENGER_MessageKind kind, const struct GNUNET
   default:
     break;
   }
+
+  if (offset >= length)
+    return;
+
+  const uint16_t padding = length - offset;
+  const uint16_t used_padding = sizeof(padding) + sizeof(char);
+
+  GNUNET_assert(padding >= used_padding);
+
+  buffer[offset++] = '\0';
+
+  if (padding > used_padding)
+    GNUNET_CRYPTO_random_block(GNUNET_CRYPTO_QUALITY_WEAK, buffer + offset, padding - used_padding);
+
+  GNUNET_memcpy(buffer + length - sizeof(padding), &padding, sizeof(padding));
 }
 
 void
-encode_message (const struct GNUNET_MESSENGER_Message *message, uint16_t length, char *buffer)
+encode_message (const struct GNUNET_MESSENGER_Message *message, uint16_t length, char *buffer,
+                int include_signature)
 {
+  GNUNET_assert((message) && (buffer));
+
   uint16_t offset = 0;
 
-  encode_step(buffer, offset, &(message->header.signature));
+  if (GNUNET_YES == include_signature)
+    encode_step_signature(buffer, offset, &(message->header.signature), length);
+
+  const kind_t kind = (kind_t) message->header.kind;
+
   encode_step(buffer, offset, &(message->header.timestamp));
   encode_step(buffer, offset, &(message->header.sender_id));
   encode_step(buffer, offset, &(message->header.previous));
-  encode_step(buffer, offset, &(message->header.kind));
+  encode_step(buffer, offset, &kind);
 
   encode_message_body (message->header.kind, &(message->body), length, buffer, offset);
 }
@@ -350,11 +465,22 @@ encode_message (const struct GNUNET_MESSENGER_Message *message, uint16_t length,
 static void
 encode_short_message (const struct GNUNET_MESSENGER_ShortMessage *message, uint16_t length, char *buffer)
 {
-  uint16_t offset = 0;
+  struct GNUNET_HashCode hash;
+  uint16_t offset = sizeof(hash);
 
-  encode_step(buffer, offset, &(message->kind));
+  const kind_t kind = (kind_t) message->kind;
+
+  encode_step(buffer, offset, &kind);
 
   encode_message_body (message->kind, &(message->body), length, buffer, offset);
+
+  GNUNET_CRYPTO_hash(
+      buffer + sizeof(hash),
+      length - sizeof(hash),
+      &hash
+  );
+
+  GNUNET_memcpy(buffer, &hash, sizeof(hash));
 }
 
 #define decode_step_ext(src, offset, dst, size) do { \
@@ -372,29 +498,51 @@ encode_short_message (const struct GNUNET_MESSENGER_ShortMessage *message, uint1
         decode_step_ext(src, offset, dst, size);                                                  \
 } while (0)
 
-static void
+#define decode_step_key(src, offset, dst, length) do {   \
+  ssize_t result = GNUNET_IDENTITY_read_key_from_buffer( \
+    dst, src + offset, length - offset                   \
+  );                                                     \
+  if (result < 0)                                        \
+    GNUNET_break(0);                                     \
+  else                                                   \
+    offset += result;                                    \
+} while (0)
+
+static uint16_t
 decode_message_body (enum GNUNET_MESSENGER_MessageKind *kind, struct GNUNET_MESSENGER_MessageBody *body,
                      uint16_t length, const char *buffer, uint16_t offset)
 {
+  uint16_t padding = 0;
+
+  GNUNET_memcpy(&padding, buffer + length - sizeof(padding), sizeof(padding));
+
+  if (padding > length - offset)
+    padding = 0;
+
+  const uint16_t end_zero = length - padding;
+
+  if ((padding) && (buffer[end_zero] != '\0'))
+    padding = 0;
+
+  length -= padding;
+
   switch (*kind)
   {
-  case GNUNET_MESSENGER_KIND_INFO:
-    decode_step(buffer, offset, &(body->info.host_key));
-    decode_step(buffer, offset, &(body->info.unique_id));
+  case GNUNET_MESSENGER_KIND_INFO: {
+    decode_step_key(buffer, offset, &(body->info.host_key), length);
+    decode_step(buffer, offset, &(body->info.messenger_version));
     break;
-  case GNUNET_MESSENGER_KIND_JOIN:
-    decode_step(buffer, offset, &(body->join.key));
-    break;
-  case GNUNET_MESSENGER_KIND_LEAVE:
+  } case GNUNET_MESSENGER_KIND_JOIN: {
+    decode_step_key(buffer, offset, &(body->join.key), length);
     break;
-  case GNUNET_MESSENGER_KIND_NAME:
+  } case GNUNET_MESSENGER_KIND_NAME:
     if (length - offset > 0)
       decode_step_malloc(buffer, offset, body->name.name, length - offset, 1);
     else
       body->name.name = NULL;
     break;
   case GNUNET_MESSENGER_KIND_KEY:
-    decode_step(buffer, offset, &(body->key.key));
+    decode_step_key(buffer, offset, &(body->key.key), length);
     break;
   case GNUNET_MESSENGER_KIND_PEER:
     decode_step(buffer, offset, &(body->peer.peer));
@@ -421,7 +569,7 @@ decode_message_body (enum GNUNET_MESSENGER_MessageKind *kind, struct GNUNET_MESS
   case GNUNET_MESSENGER_KIND_FILE:
     decode_step(buffer, offset, &(body->file.key));
     decode_step(buffer, offset, &(body->file.hash));
-    decode_step_ext(buffer, offset, body->file.name, NAME_MAX);
+    decode_step_ext(buffer, offset, body->file.name, sizeof(body->file.name));
     decode_step_malloc(buffer, offset, body->file.uri, length - offset, 1);
     break;
   case GNUNET_MESSENGER_KIND_PRIVATE:
@@ -434,26 +582,51 @@ decode_message_body (enum GNUNET_MESSENGER_MessageKind *kind, struct GNUNET_MESS
     *kind = GNUNET_MESSENGER_KIND_UNKNOWN;
     break;
   }
+
+  return padding;
 }
 
 int
-decode_message (struct GNUNET_MESSENGER_Message *message, uint16_t length, const char *buffer)
+decode_message (struct GNUNET_MESSENGER_Message *message, uint16_t length, const char *buffer,
+                int include_signature, uint16_t *padding)
 {
+  GNUNET_assert((message) && (buffer));
+
   uint16_t offset = 0;
 
-  if (length < get_message_kind_size (GNUNET_MESSENGER_KIND_UNKNOWN))
+  if (GNUNET_YES == include_signature)
+  {
+    ssize_t result = GNUNET_IDENTITY_read_signature_from_buffer(
+        &(message->header.signature), buffer, length - offset
+    );
+
+    if (result < 0)
+      return GNUNET_NO;
+    else
+      offset += result;
+  }
+
+  const uint16_t count = length - offset;
+
+  if (count < get_message_kind_size (GNUNET_MESSENGER_KIND_UNKNOWN))
     return GNUNET_NO;
 
-  decode_step(buffer, offset, &(message->header.signature));
+  kind_t kind;
+
   decode_step(buffer, offset, &(message->header.timestamp));
   decode_step(buffer, offset, &(message->header.sender_id));
   decode_step(buffer, offset, &(message->header.previous));
-  decode_step(buffer, offset, &(message->header.kind));
+  decode_step(buffer, offset, &kind);
 
-  if (length < get_message_kind_size (message->header.kind))
+  message->header.kind = (enum GNUNET_MESSENGER_MessageKind) kind;
+
+  if (count < get_message_kind_size (message->header.kind))
     return GNUNET_NO;
 
-  decode_message_body (&(message->header.kind), &(message->body), length, buffer, offset);
+  const uint16_t result = decode_message_body (&(message->header.kind), &(message->body), length, buffer, offset);
+
+  if (padding)
+    *padding = result;
 
   return GNUNET_YES;
 }
@@ -461,47 +634,80 @@ decode_message (struct GNUNET_MESSENGER_Message *message, uint16_t length, const
 static int
 decode_short_message (struct GNUNET_MESSENGER_ShortMessage *message, uint16_t length, const char *buffer)
 {
-  uint16_t offset = 0;
+  struct GNUNET_HashCode expected, hash;
+  uint16_t offset = sizeof(hash);
+
+  if (length < get_short_message_size (NULL, GNUNET_NO))
+    return GNUNET_NO;
+
+  GNUNET_memcpy(&hash, buffer, sizeof(hash));
+
+  GNUNET_CRYPTO_hash(
+      buffer + sizeof(hash),
+      length - sizeof(hash),
+      &expected
+  );
 
-  if (length < get_short_message_size (NULL))
+  if (0 != GNUNET_CRYPTO_hash_cmp(&hash, &expected))
     return GNUNET_NO;
 
-  decode_step(buffer, offset, &(message->kind));
+  kind_t kind;
 
-  if (length < get_short_message_size (message))
+  decode_step(buffer, offset, &kind);
+
+  message->kind = (enum GNUNET_MESSENGER_MessageKind) kind;
+
+  if (length < get_short_message_size (message, GNUNET_NO))
     return GNUNET_NO;
 
   decode_message_body (&(message->kind), &(message->body), length, buffer, offset);
 
+  if (GNUNET_MESSENGER_KIND_UNKNOWN == message->kind)
+    return GNUNET_NO;
+
   return GNUNET_YES;
 }
 
 void
-hash_message (uint16_t length, const char *buffer, struct GNUNET_HashCode *hash)
+hash_message (const struct GNUNET_MESSENGER_Message *message, uint16_t length, const char *buffer,
+              struct GNUNET_HashCode *hash)
 {
-  GNUNET_CRYPTO_hash (buffer + sizeof(struct GNUNET_CRYPTO_EcdsaSignature),
-                      length - sizeof(struct GNUNET_CRYPTO_EcdsaSignature), hash);
+  GNUNET_assert((message) && (buffer) && (hash));
+
+  const ssize_t offset = GNUNET_IDENTITY_signature_get_length(
+      &(message->header.signature)
+  );
+
+  GNUNET_CRYPTO_hash (buffer + offset, length - offset, hash);
 }
 
 void
 sign_message (struct GNUNET_MESSENGER_Message *message, uint16_t length, char *buffer,
               const struct GNUNET_HashCode *hash, const struct GNUNET_MESSENGER_Ego *ego)
 {
+  GNUNET_assert((message) && (buffer) && (hash) && (ego));
+
   struct GNUNET_MESSENGER_MessageSignature signature;
 
   signature.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_CHAT_MESSAGE);
   signature.purpose.size = htonl (sizeof(signature));
 
   GNUNET_memcpy(&(signature.hash), hash, sizeof(struct GNUNET_HashCode));
-
   GNUNET_IDENTITY_sign(&(ego->priv), &signature, &(message->header.signature));
-  GNUNET_memcpy(buffer, &(message->header.signature), sizeof(struct GNUNET_CRYPTO_EcdsaSignature));
+
+  uint16_t offset = 0;
+  encode_step_signature(buffer, offset, &(message->header.signature), length);
 }
 
 int
 verify_message (const struct GNUNET_MESSENGER_Message *message, const struct GNUNET_HashCode *hash,
                 const struct GNUNET_IDENTITY_PublicKey *key)
 {
+  GNUNET_assert((message) && (hash) && (key));
+
+  if (ntohl (key->type) != ntohl (message->header.signature.type))
+    return GNUNET_SYSERR;
+
   struct GNUNET_MESSENGER_MessageSignature signature;
 
   signature.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_CHAT_MESSAGE);
@@ -516,26 +722,32 @@ verify_message (const struct GNUNET_MESSENGER_Message *message, const struct GNU
 int
 encrypt_message (struct GNUNET_MESSENGER_Message *message, const struct GNUNET_IDENTITY_PublicKey *key)
 {
+  GNUNET_assert((message) && (key));
+
   struct GNUNET_MESSENGER_ShortMessage shortened;
 
   fold_short_message (message, &shortened);
 
-  const uint16_t length = get_short_message_size (&shortened);
+  const uint16_t length = get_short_message_size (&shortened, GNUNET_YES);
+  const uint16_t padded_length = calc_padded_length(length);
 
   message->header.kind = GNUNET_MESSENGER_KIND_PRIVATE;
-  message->body.private.data = GNUNET_malloc(length);
+  message->body.private.data = GNUNET_malloc(padded_length);
+  message->body.private.length = padded_length;
 
-  encode_short_message (&shortened, length, message->body.private.data);
+  encode_short_message (&shortened, padded_length, message->body.private.data);
 
-  if (GNUNET_IDENTITY_encrypt (message->body.private.data, length, key, &(message->body.private.key),
-                               message->body.private.data)
-      == length)
+  if (padded_length == GNUNET_IDENTITY_encrypt (message->body.private.data, padded_length, key,
+                                                &(message->body.private.key),
+                                                message->body.private.data))
   {
     destroy_message_body (shortened.kind, &(shortened.body));
     return GNUNET_YES;
   }
   else
   {
+    GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Encrypting message failed!\n");
+
     unfold_short_message (&shortened, message);
     return GNUNET_NO;
   }
@@ -544,18 +756,28 @@ encrypt_message (struct GNUNET_MESSENGER_Message *message, const struct GNUNET_I
 int
 decrypt_message (struct GNUNET_MESSENGER_Message *message, const struct GNUNET_IDENTITY_PrivateKey *key)
 {
-  if (message->body.private.length != GNUNET_IDENTITY_decrypt (message->body.private.data,
-                                                               message->body.private.length, key,
-                                                               &(message->body.private.key),
+  GNUNET_assert((message) && (key));
+
+  if (message->body.private.length != GNUNET_IDENTITY_decrypt (message->body.private.data, message->body.private.length,
+                                                               key, &(message->body.private.key),
                                                                message->body.private.data))
+  {
+    GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Decrypting message failed!\n");
+
     return GNUNET_NO;
+  }
 
   struct GNUNET_MESSENGER_ShortMessage shortened;
 
   if (GNUNET_YES != decode_short_message (&shortened, message->body.private.length, message->body.private.data))
+  {
+    GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Decoding decrypted message failed!\n");
+
     return GNUNET_NO;
+  }
 
   unfold_short_message (&shortened, message);
+
   return GNUNET_YES;
 }
 
@@ -563,18 +785,25 @@ struct GNUNET_MQ_Envelope*
 pack_message (struct GNUNET_MESSENGER_Message *message, struct GNUNET_HashCode *hash,
               const struct GNUNET_MESSENGER_Ego *ego, int mode)
 {
-  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Packing message: %u\n", message->header.kind);
+  GNUNET_assert(message);
+
+  if (ego)
+    message->header.signature.type = ego->priv.type;
+
+  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Packing message kind=%u and sender: %s\n",
+             message->header.kind, GNUNET_sh2s(&(message->header.sender_id)));
 
   struct GNUNET_MessageHeader *header;
 
-  uint16_t length = get_message_size (message);
+  const uint16_t length = get_message_size (message, GNUNET_YES);
+  const uint16_t padded_length = calc_padded_length(length);
 
   struct GNUNET_MQ_Envelope *env;
   char *buffer;
 
   if (GNUNET_MESSENGER_PACK_MODE_ENVELOPE == mode)
   {
-    env = GNUNET_MQ_msg_extra(header, length, GNUNET_MESSAGE_TYPE_CADET_CLI);
+    env = GNUNET_MQ_msg_extra(header, padded_length, GNUNET_MESSAGE_TYPE_CADET_CLI);
 
     buffer = (char*) &(header[1]);
   }
@@ -582,14 +811,14 @@ pack_message (struct GNUNET_MESSENGER_Message *message, struct GNUNET_HashCode *
   {
     env = NULL;
 
-    buffer = GNUNET_malloc(length);
+    buffer = GNUNET_malloc(padded_length);
   }
 
-  encode_message (message, length, buffer);
+  encode_message (message, padded_length, buffer, GNUNET_YES);
 
   if (hash)
   {
-    hash_message (length, buffer, hash);
+    hash_message (message, length, buffer, hash);
 
     if (ego)
       sign_message (message, length, buffer, hash, ego);
@@ -600,3 +829,43 @@ pack_message (struct GNUNET_MESSENGER_Message *message, struct GNUNET_HashCode *
 
   return env;
 }
+
+int
+filter_message_sending (const struct GNUNET_MESSENGER_Message *message)
+{
+  switch (message->header.kind)
+  {
+  case GNUNET_MESSENGER_KIND_INFO:
+    return GNUNET_SYSERR; // Reserved for connection handling only!
+  case GNUNET_MESSENGER_KIND_JOIN:
+    return GNUNET_NO; // Use #GNUNET_MESSENGER_enter_room(...) instead!
+  case GNUNET_MESSENGER_KIND_LEAVE:
+    return GNUNET_NO; // Use #GNUNET_MESSENGER_close_room(...) instead!
+  case GNUNET_MESSENGER_KIND_NAME:
+    return GNUNET_YES;
+  case GNUNET_MESSENGER_KIND_KEY:
+    return GNUNET_NO; // Use #GNUNET_MESSENGER_update(...) instead!
+  case GNUNET_MESSENGER_KIND_PEER:
+    return GNUNET_NO; // Use #GNUNET_MESSENGER_open_room(...) instead!
+  case GNUNET_MESSENGER_KIND_ID:
+    return GNUNET_SYSERR; // Reserved for member id handling only!
+  case GNUNET_MESSENGER_KIND_MISS:
+    return GNUNET_SYSERR; // Reserved for connection handling only!
+  case GNUNET_MESSENGER_KIND_MERGE:
+    return GNUNET_YES;
+  case GNUNET_MESSENGER_KIND_REQUEST:
+    return GNUNET_YES;
+  case GNUNET_MESSENGER_KIND_INVITE:
+    return GNUNET_YES;
+  case GNUNET_MESSENGER_KIND_TEXT:
+    return GNUNET_YES;
+  case GNUNET_MESSENGER_KIND_FILE:
+    return GNUNET_YES;
+  case GNUNET_MESSENGER_KIND_PRIVATE:
+    return GNUNET_NO; // Use #GNUNET_MESSENGER_send_message(...) with a contact instead!
+  case GNUNET_MESSENGER_KIND_DELETE:
+    return GNUNET_YES;
+  default:
+    return GNUNET_SYSERR;
+  }
+}