Merge #14025: p2p: Remove dead code for nVersion=10300

fa74d3d qa: Remove unused deserialization code in msg_version (MarcoFalke)
fa5099c p2p: Remove dead code for nVersion=10300 (MarcoFalke)

Pull request description:

  This code is undocumented and confusing as well as dead, since peers with a version that old are disconnected immediately.

Tree-SHA512: 58c131a2730b630ffdc191cd65fe736ed1bd57e184902e2af1b1399443c4654617e68774432016df023434055e85d2e8cd32fb03b40c508c3bb8db6d19427434

Author: MarcoFalke

src/net_processing.cpp

@@ -1662,8 +1662,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             return false;
         }
 
-        if (nVersion < MIN_PEER_PROTO_VERSION)
-        {
+        if (nVersion < MIN_PEER_PROTO_VERSION) {
             // disconnect from peers older than this proto version
             LogPrint(BCLog::NET, "peer=%d using obsolete version %i; disconnecting\n", pfrom->GetId(), nVersion);
             if (enable_bip61) {
@@ -1674,8 +1673,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             return false;
         }
 
-        if (nVersion == 10300)
-            nVersion = 300;
         if (!vRecv.empty())
             vRecv >> addrFrom >> nNonce;
         if (!vRecv.empty()) {

test/functional/test_framework/messages.py

@@ -904,28 +904,17 @@ def __init__(self):
 
     def deserialize(self, f):
         self.nVersion = struct.unpack("<i", f.read(4))[0]
-        if self.nVersion == 10300:
-            self.nVersion = 300
         self.nServices = struct.unpack("<Q", f.read(8))[0]
         self.nTime = struct.unpack("<q", f.read(8))[0]
         self.addrTo = CAddress()
         self.addrTo.deserialize(f, False)
 
-        if self.nVersion >= 106:
-            self.addrFrom = CAddress()
-            self.addrFrom.deserialize(f, False)
-            self.nNonce = struct.unpack("<Q", f.read(8))[0]
-            self.strSubVer = deser_string(f)
-        else:
-            self.addrFrom = None
-            self.nNonce = None
-            self.strSubVer = None
-            self.nStartingHeight = None
+        self.addrFrom = CAddress()
+        self.addrFrom.deserialize(f, False)
+        self.nNonce = struct.unpack("<Q", f.read(8))[0]
+        self.strSubVer = deser_string(f)
 
-        if self.nVersion >= 209:
-            self.nStartingHeight = struct.unpack("<i", f.read(4))[0]
-        else:
-            self.nStartingHeight = None
+        self.nStartingHeight = struct.unpack("<i", f.read(4))[0]
 
         if self.nVersion >= 70001:
             # Relay field is optional for version 70001 onwards