Fix handshake code example, updating answer and comments.

ch10.asciidoc

@@ -170,13 +170,12 @@ Now that we have a node, we can handshake with another node:
 >>> node.send(version)  # <2>
 >>> verack_received = False
 >>> version_received = False
->>> while not verack_received and not version_received:  # <3>
+>>> while not (verack_received and version_received):  # <3>
 ...     message = node.wait_for(VersionMessage, VerAckMessage)  # <4>
 ...     if message.command == VerAckMessage.command:
 ...         verack_received = True
 ...     else:
 ...         version_received = True
-...         node.send(VerAckMessage())
 ----
 <1> Most nodes don't care about the fields in `version` like IP address.
 We can connect with the defaults and everything will be just fine.

code-ch10/answers.py

@@ -150,7 +150,14 @@ def serialize(self):
 def handshake(self):
     version = VersionMessage()
     self.send(version)
-    self.wait_for(VerAckMessage)
+    verack_received = False
+    version_received = False
+    while not (verack_received and version_received):
+        message = self.wait_for(VerAckMessage, VersionMessage)
+        if message.command == VerAckMessage.command:
+            verack_received = True
+        else:
+            version_received = True
 # end::answer5[]
 
 

code-ch10/network.py

@@ -284,10 +284,11 @@ def __init__(self, host, port=None, testnet=False, logging=False):
 
     def handshake(self):
         '''Do a handshake with the other node.
-        Handshake is sending a version message and getting a verack back.'''
+        Handshake is sending a version message, getting a verack back,
+        receiving a version, and sending a verack.'''
         # create a version message
         # send the command
-        # wait for a verack message
+        # wait for verack and version messages
         raise NotImplementedError
     # tag::source4[]