Handle client protocol range requests.

Add more tests.

lib/util.py

@@ -278,3 +278,27 @@ def protocol_tuple(s):
         return tuple(int(part) for part in s.split('.'))
     except Exception:
         return (0, )
+
+def protocol_version(client_req, server_min, server_max):
+    '''Given a client protocol request, return the protocol version
+    to use as a tuple.
+
+    If a mutually acceptable protocol version does not exist, return None.
+    '''
+    if isinstance(client_req, list) and len(client_req) == 2:
+        client_min, client_max = client_req
+    elif client_req is None:
+        client_min = client_max = server_min
+    else:
+        client_min = client_max = client_req
+
+    client_min = protocol_tuple(client_min)
+    client_max = protocol_tuple(client_max)
+    server_min = protocol_tuple(server_min)
+    server_max = protocol_tuple(server_max)
+
+    result = min(client_max, server_max)
+    if result < max(client_min, server_min) or result == (0, ):
+        result = None
+
+    return result

server/session.py

@@ -367,19 +367,18 @@ class ElectrumX(SessionBase):
 
             return message
 
-    def set_protocol_handlers(self, version_str):
-        controller = self.controller
-        if version_str is None:
-            version_str = version.PROTOCOL_MIN
-        ptuple = util.protocol_tuple(version_str)
-        # Disconnect if requested protocol version in unsupported
-        if (ptuple < util.protocol_tuple(version.PROTOCOL_MIN)
-                or ptuple > util.protocol_tuple(version.PROTOCOL_MAX)):
-            self.log_info('unsupported protocol version {}'
-                          .format(version_str))
+    def set_protocol_handlers(self, version_req):
+        # Find the highest common protocol version.  Disconnect if
+        # that protocol version in unsupported.
+        ptuple = util.protocol_version(version_req, version.PROTOCOL_MIN,
+                                       version.PROTOCOL_MAX)
+        if ptuple is None:
+            self.log_info('unsupported protocol version request {}'
+                          .format(version_req))
             raise RPCError('unsupported protocol version: {}'
-                           .format(version_str), JSONRPC.FATAL_ERROR)
+                           .format(version_req), JSONRPC.FATAL_ERROR)
 
+        controller = self.controller
         handlers = {
             'blockchain.address.get_balance': controller.address_get_balance,
             'blockchain.address.get_history': controller.address_get_history,

tests/lib/test_util.py

@@ -93,3 +93,20 @@ def test_protocol_tuple():
     assert util.protocol_tuple("0.1") == (0, 1)
     assert util.protocol_tuple("0.10") == (0, 10)
     assert util.protocol_tuple("2.5.3") == (2, 5, 3)
+
+def test_protocol_version():
+    assert util.protocol_version(None, "1.0", "1.0") == (1, 0)
+    assert util.protocol_version("0.10", "0.10", "1.1") == (0, 10)
+
+    assert util.protocol_version("1.0", "1.0", "1.0") == (1, 0)
+    assert util.protocol_version("1.0", "1.0", "1.1") == (1, 0)
+    assert util.protocol_version("1.1", "1.0", "1.1") == (1, 1)
+    assert util.protocol_version("1.2", "1.0", "1.1") is None
+    assert util.protocol_version("0.9", "1.0", "1.1") is None
+
+    assert util.protocol_version(["0.9", "1.0"], "1.0", "1.1") == (1, 0)
+    assert util.protocol_version(["0.9", "1.1"], "1.0", "1.1") == (1, 1)
+    assert util.protocol_version(["1.1", "0.9"], "1.0", "1.1") is None
+    assert util.protocol_version(["0.8", "0.9"], "1.0", "1.1") is None
+    assert util.protocol_version(["1.1", "1.2"], "1.0", "1.1") == (1, 1)
+    assert util.protocol_version(["1.2", "1.3"], "1.0", "1.1") is None