net: parse reject earlier

Prior to this change, all messages were ignored until a VERSION message was
received, as well as possibly incurring a ban score.

Since REJECT messages can be sent at any time (including as a response to a bad
VERSION message), make sure to always parse them.

Moving this parsing up keeps it from being caught in the
if (pfrom->nVersion == 0) check below.

Author: theuni

src/net_processing.cpp

@@ -1190,8 +1190,31 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         }
     }
 
+    if (strCommand == NetMsgType::REJECT)
+    {
+        if (fDebug) {
+            try {
+                std::string strMsg; unsigned char ccode; std::string strReason;
+                vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, MAX_REJECT_MESSAGE_LENGTH);
+
+                std::ostringstream ss;
+                ss << strMsg << " code " << itostr(ccode) << ": " << strReason;
 
-    if (strCommand == NetMsgType::VERSION)
+                if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX)
+                {
+                    uint256 hash;
+                    vRecv >> hash;
+                    ss << ": hash " << hash.ToString();
+                }
+                LogPrint("net", "Reject %s\n", SanitizeString(ss.str()));
+            } catch (const std::ios_base::failure&) {
+                // Avoid feedback loops by preventing reject messages from triggering a new reject message.
+                LogPrint("net", "Unparseable reject message received\n");
+            }
+        }
+    }
+
+    else if (strCommand == NetMsgType::VERSION)
     {
         // Each connection can only send one version message
         if (pfrom->nVersion != 0)
@@ -2544,31 +2567,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         pfrom->fRelayTxes = true;
     }
 
-
-    else if (strCommand == NetMsgType::REJECT)
-    {
-        if (fDebug) {
-            try {
-                std::string strMsg; unsigned char ccode; std::string strReason;
-                vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, MAX_REJECT_MESSAGE_LENGTH);
-
-                std::ostringstream ss;
-                ss << strMsg << " code " << itostr(ccode) << ": " << strReason;
-
-                if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX)
-                {
-                    uint256 hash;
-                    vRecv >> hash;
-                    ss << ": hash " << hash.ToString();
-                }
-                LogPrint("net", "Reject %s\n", SanitizeString(ss.str()));
-            } catch (const std::ios_base::failure&) {
-                // Avoid feedback loops by preventing reject messages from triggering a new reject message.
-                LogPrint("net", "Unparseable reject message received\n");
-            }
-        }
-    }
-
     else if (strCommand == NetMsgType::FEEFILTER) {
         CAmount newFeeFilter = 0;
         vRecv >> newFeeFilter;