test: p2p: introduce helper for sending prepared VERSION message

This deduplicates code for sending out the VERSION message
(if available and not sent yet), currently used at three
different places:

1) in the `connection_made` asyncio callback
   (for v1 connections that are not v2 reconnects)
2) at the end of `v2_handshake`, if the v2 handshake succeeded
3) in the `on_version` callback, if a reconnection with v1 happens

Author: theStack

test/functional/test_framework/p2p.py

@@ -226,9 +226,8 @@ def connection_made(self, transport):
             self.send_raw_message(send_handshake_bytes)
         # if v2 connection, send `on_connection_send_msg` after initial v2 handshake.
         # if reconnection situation, send `on_connection_send_msg` after version message is received in `on_version()`.
-        if self.on_connection_send_msg and not self.supports_v2_p2p and not self.reconnect:
-            self.send_message(self.on_connection_send_msg)
-            self.on_connection_send_msg = None  # Never used again
+        if not self.supports_v2_p2p and not self.reconnect:
+            self.send_version()
         self.on_open()
 
     def connection_lost(self, exc):
@@ -284,9 +283,8 @@ def v2_handshake(self):
         if not is_mac_auth:
             raise ValueError("invalid v2 mac tag in handshake authentication")
         self.recvbuf = self.recvbuf[length:]
-        if self.v2_state.tried_v2_handshake and self.on_connection_send_msg:
-            self.send_message(self.on_connection_send_msg)
-            self.on_connection_send_msg = None
+        if self.v2_state.tried_v2_handshake:
+            self.send_version()
 
     # Socket read methods
 
@@ -559,9 +557,7 @@ def on_version(self, message):
         assert message.nVersion >= MIN_P2P_VERSION_SUPPORTED, "Version {} received. Test framework only supports versions greater than {}".format(message.nVersion, MIN_P2P_VERSION_SUPPORTED)
         # reconnection using v1 P2P has happened since version message can be processed, previously unsent version message is sent using v1 P2P here
         if self.reconnect:
-            if self.on_connection_send_msg:
-                self.send_message(self.on_connection_send_msg)
-                self.on_connection_send_msg = None
+            self.send_version()
             self.reconnect = False
         if message.nVersion >= 70016 and self.wtxidrelay:
             self.send_message(msg_wtxidrelay())
@@ -676,6 +672,11 @@ def test_function():
 
     # Message sending helper functions
 
+    def send_version(self):
+        if self.on_connection_send_msg:
+            self.send_message(self.on_connection_send_msg)
+            self.on_connection_send_msg = None  # Never used again
+
     def send_and_ping(self, message, timeout=60):
         self.send_message(message)
         self.sync_with_ping(timeout=timeout)