The following post is a continuation of discussion which started
here.
And that's how you learned that "Routing" type messages do not contain any routing instructions or liquidity information.
bolt07 messages: announcement_signatures, channel_announcement, node_announcement, query_short_channel_ids/reply_short_channel_ids_end, channel_update, query_channel_range/reply_channel_range
Their types are: 259, 256, 257, 261, 258, 263, 264 respectively.
None of these messages include "onion_routing_packet", "hop_data" or any other routing instructions.
even simple messages like ping and pong can add payloads of different information, well outside of your "update_add_htlc" mantra where you think everything is done inside
Again, just because you can technically fit some data inside ping/pong messages, it doesn't mean that the other node expects it. In fact, you should not send any data using them:
type: 18 (ping)
data:
[u16:num_pong_bytes]
[u16:byteslen]
[byteslen*byte:ignored]
A node sending a ping message:
SHOULD set ignored to 0s.
MUST NOT set ignored to sensitive data such as secrets or portions of initialized memory.
So, as per specifications, the data sent through ping/pong messages is just a bunch of zeros.
3. maybe the many ways many wallets do it, is not spec compliant to YOUR wallet. but your wallet after all is not interested in privacy, hense why you think your wallet is limited to only a dozen message types.
Feel free to name those privacy-oriented wallets which do not follow the specifications to improve the privacy of their users.
EG W does not tell X about C because WC is private. so X cant tell y and Y cannot tell Z .
so you as Z will just see Z-Y-X-W but not -C..
As Z, you won't learn about the CW channel, but you can still learn about AB, BC, CD, DE from either W, who can learn about them from C, or from some outside node which had received a gossip message about any of those channels. W can safely forward gossip messages from C as those messages are exactly the same for every hop.