add most flows

books/protocol/src/SUMMARY.md

@@ -26,4 +26,10 @@
     - [Admin Messages](./p2p_network/levin/admin.md)
     - [Protocol Messages](./p2p_network/levin/protocol.md)
   - [Common Types](./p2p_network/common_types.md)
+  - [Message Flows](./p2p_network/message_flows.md)
+    - [Handshake](./p2p_network/message_flows/handshake.md)
+    - [Timed Sync](./p2p_network/message_flows/timed_sync.md)
+    - [New Block](./p2p_network/message_flows/new_block.md)
+    - [New Transactions](./p2p_network/message_flows/new_transactions.md)
+    - [Chain Sync](./p2p_network/message_flows/chain_sync.md)
 - [Pruning](./pruning.md)

books/protocol/src/p2p_network/message_flows.md

@@ -0,0 +1,19 @@
+# Message Flows
+
+Message flows are sets of messages sent between peers, that achieve an identifiable goal, like a handshake.
+Some message flows are complex, involving many message types, whereas others are simple, requiring only 1.
+
+The message flows here are not every possible request/response.
+
+When documenting checks on the messages, checks not on the message will not be included. For example when receiving
+a handshake monerod will check if we have too many incoming connections, this check would not be included in the
+checks on the handshake request.
+
+## Different Flows
+
+- [Handshakes](./message_flows/handshake.md)
+- [Timed Sync](./message_flows/timed_sync.md)
+- [New Block](./message_flows/new_block.md)
+- [New Transactions](./message_flows/new_transactions.md)
+- [Chain Sync](./message_flows/chain_sync.md)
+

books/protocol/src/p2p_network/message_flows/handshake.md

@@ -0,0 +1,51 @@
+# Handshakes
+
+Handshakes are used to establish connections to peers.
+
+## Flow
+
+The default handshake flow is made up of the connecting peer sending a [handshake request](../levin/admin.md#handshake-request) and the
+receiving peer responding with a [handshake response](../levin/admin.md#handshake-response).
+
+It should be noted that not all other messages are banned during handshakes, for example support flag requests can be sent and even some protocol
+requests.
+
+### Handshake Request Checks
+
+The receiving peer will check:
+
+- The `network_id` is network ID expected.[^network-id]
+- The connection is an incoming connection.[^req-incoming-only]
+- The peer hasn't already completed a handshake.[^double-handshake]
+- If the network zone is public, then the `peer_id` must not be the same as ours.[^same-peer-id]
+- The core sync data is not malformed.[^core-sync-data-checks]
+
+### Handshake Response Checks
+
+Teh initiating peer will check:
+
+- The `network_id` is network ID expected.[^res-network-id]
+- The number of peers in the peer list is less than `250`.[^max-peer-list-res]
+- All peers in the peer list are in the same zone.[^peers-all-in-same-zone]
+- The core sync data is not malformed.[^core-sync-data-checks]
+- If the network zone is public, then the `peer_id` must not be the same as ours.[^same-peer-id-res]
+
+---
+
+[^network-id]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2510>
+
+[^req-incoming-only]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2519>
+
+[^double-handshake]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2527>
+
+[^same-peer-id]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2539>
+
+[^core-sync-data-checks]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/cryptonote_protocol/cryptonote_protocol_handler.inl#L341>
+
+[^res-network-id]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L1164>
+
+[^max-peer-list-res]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2170>
+
+[^peers-all-in-same-zone]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2182>
+
+[^same-peer-id-res]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L1195>

books/protocol/src/p2p_network/message_flows/new_block.md

@@ -0,0 +1,29 @@
+# New Block
+
+This is used whenever a new block is to be sent to peers. Only the fluffy block flow is described here, as the other method is depreciated.
+
+## Flow
+
+First the peer with the new block will send a [new fluffy block](../levin/protocol.md#notify-new-fluffy-block) notification, if the receiving
+peer has all the txs in the block then the flow is complete. Otherwise the peer sends a [fluffy missing transactions request](../levin/protocol.md#notify-request-fluffy-missing-tx) 
+to the first peer, the first peer will then respond with again a [new fluffy block](../levin/protocol.md#notify-new-fluffy-block) notification but
+with the transactions requested.  
+
+```bob
+                          
+     ,----------.          ,----------.  
+     |Initiator |          | Receiver |
+     `-----+----'          `-----+----'
+           |  New Fluffy Block   |
+           |-------------------->|
+           |                     |
+           | Missing Txs Request |
+           |<- - - - - - - - - - |
+           |                     |
+           |  New Fluffy Block   |
+           | - - - - - - - - - ->|
+           |                     |
+           |                     |
+           V                     v
+```
+

books/protocol/src/p2p_network/message_flows/new_transactions.md

@@ -0,0 +1,16 @@
+# New Transactions
+
+Monero uses the dandelion++ protocol to pass transactions around the network, this flow just describes the actual tx passing between nodes part.
+
+## Flow
+
+This flow is pretty simple, the txs are put into a [new transactions](../levin/protocol.md#notify-new-transactions) notification and sent to
+peers.
+
+Hopefully in the future [this is changed](https://github.com/monero-project/monero/issues/9334).
+
+There must be no duplicate txs in the notification.[^duplicate-txs]
+
+---
+
+[^duplicate-txs]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/cryptonote_protocol/cryptonote_protocol_handler.inl#L991>

books/protocol/src/p2p_network/message_flows/timed_sync.md

@@ -0,0 +1,28 @@
+# Timed Syncs
+
+A timed sync request is sent every 60 seconds to make sure the connection is still live.
+
+## Flow
+
+First the timed sync initiator will send a [timed sync request](../levin/admin.md#timed-sync-request), the receiver will then
+respond with a [timed sync response](../levin/admin.md#timed-sync-response)
+
+### Timed Sync Request Checks
+
+- The core sync data is not malformed.[^core-sync-data-checks]
+
+
+### Timed Sync Response Checks
+
+- The core sync data is not malformed.[^core-sync-data-checks]
+- The number of peers in the peer list is less than `250`.[^max-peer-list-res]
+- All peers in the peer list are in the same zone.[^peers-all-in-same-zone]
+
+---
+
+[^core-sync-data-checks]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2464>
+
+[^max-peer-list-res]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2170>
+
+[^peers-all-in-same-zone]: <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/p2p/net_node.inl#L2182>
+