Refactor test for existing peer connection into own function

src/net.h

@@ -442,6 +442,12 @@ private:
     CNode* FindNode(const std::string& addrName);
     CNode* FindNode(const CService& addr);
 
+    /**
+     * Determine whether we're already connected to a given address, in order to
+     * avoid initiating duplicate connections.
+     */
+    bool AlreadyConnectedToAddress(const CAddress& addr);
+
     bool AttemptToEvictConnection();
     CNode* ConnectNode(CAddress addrConnect, const char *pszDest, bool fCountFailure, ConnectionType conn_type);
     void AddWhitelistPermissionFlags(NetPermissionFlags& flags, const CNetAddr &addr) const;