This makes the sending side of P2P transports mirror the receiver side: caller provides
message (consisting of type and payload) to be sent, and then asks what bytes must be
sent. Once the message has been fully sent, a new message can be provided.
This removes the assumption that P2P serialization of messages follows a strict structure
of header (a function of type and payload), followed by (unmodified) payload, and instead
lets transports decide the structure themselves.
It also removes the assumption that a message must always be sent at once, or that no
bytes are even sent on the wire when there is no message. This opens the door for
supporting traffic shaping mechanisms in the future.
This allows state that is shared between both directions to be encapsulated
into a single object. Specifically the v2 transport protocol introduced by
BIP324 has sending state (the encryption keys) that depends on received
messages (the DH key exchange). Having a single object for both means it can
hide logic from callers related to that key exchange and other interactions.
cd0c8eeb09 [net] Pass nRecvFloodSize to CNode (dergoegge)
860402ef2e [net] Remove trivial GetConnectionType() getter (dergoegge)
b5a85b365a [net] Delete CNetMessage copy constructor/assignment op (dergoegge)
Pull request description:
Follow-up PR for #27257
* Deletes the copy constructor/assignment operator of `CNetMessage`
* Removes trivial getter for the connection type
* Avoids passing `nRecvFloodSize` to CNode methods by passing it to `CNode` on creation
ACKs for top commit:
jnewbery:
utACK cd0c8eeb09
theStack:
ACK cd0c8eeb09
Tree-SHA512: 673a758668617f69fba77e61f0eaa1538da27a4849c82c98742436692baa2d7f001129af3e7a66b160e599d12109dac08137a146f10ff9b9ebdc5c2237311d41
At the time when
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), it);
```
is called, `it` is certainly `pnode->vRecvMsg.end()` which makes the
call equivalent to:
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), pnode->vRecvMsg.end());
```
which is equivalent to:
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg);
```
Thus, use the latter. Further, maybe irrelevant, but the latter has
constant complexity while the original code is `O(length of vRecvMsg)`.
