From fe910d021c74ef73e086138a192be32f2110e07b Mon Sep 17 00:00:00 2001
From: alex <alex@cloudware.io>
Date: Fri, 11 Dec 2020 15:56:05 +0100
Subject: [PATCH] session: allow clients to query server.version after
 negotitation

There's no reason why the server wouldn't want to report its software
and protocol versions after the negotiation. This can be used, for
example, by a stateless client.

This is backwards compatible.
---
 docs/protocol-changes.rst   | 17 +++++++++++++----
 docs/protocol-methods.rst   |  4 +++-
 electrumx/server/session.py |  2 +-
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/docs/protocol-changes.rst b/docs/protocol-changes.rst
index d3faa6e7b..e47902f9d 100644
--- a/docs/protocol-changes.rst
+++ b/docs/protocol-changes.rst
@@ -147,6 +147,8 @@ Removed methods
   * :func:`blockchain.block.get_header`
   * :func:`blockchain.block.get_chunk`
 
+.. _version 1.4.1:
+
 Version 1.4.1
 =============
 
@@ -158,11 +160,18 @@ Changes
     nonzero.  AuxPoW data is still present when *cp_height* is zero.
     Non-AuxPoW chains are unaffected.
 
-
-Version 1.4.1
-=============
-
 New methods
 -----------
 
   * :func:`blockchain.scipthash.unsubscribe` to unsubscribe from a script hash.
+
+.. _version 1.4.2:
+
+Version 1.4.2
+=============
+
+Changes
+-------
+
+  * :func:`server.version` now always reports the current versions in use;
+    however, only the first message performs protocol negotiation.
diff --git a/docs/protocol-methods.rst b/docs/protocol-methods.rst
index 1467d4627..85290a5db 100644
--- a/docs/protocol-methods.rst
+++ b/docs/protocol-methods.rst
@@ -968,7 +968,9 @@ server.version
 ==============
 
 Identify the client to the server and negotiate the protocol version.
-Only the first :func:`server.version` message is accepted.
+The first :func:`server.version` message performs the protocol version
+negotiation as described below. Subsequent calls simply return the negotiated
+version.
 
 **Signature**
 
diff --git a/electrumx/server/session.py b/electrumx/server/session.py
index 9acde44c6..44ce9e82f 100644
--- a/electrumx/server/session.py
+++ b/electrumx/server/session.py
@@ -1337,7 +1337,7 @@ async def server_version(self, client_name='', protocol_version=None):
         '''
         self.bump_cost(0.5)
         if self.sv_seen:
-            raise RPCError(BAD_REQUEST, f'server.version already sent')
+            return electrumx.version, self.protocol_version_string()
         self.sv_seen = True
 
         if client_name: