1 files changed, 16 insertions, 4 deletions

diff --git a/src/net.cpp b/src/net.cpp
index 941ea3c4ac..633f9a2f7f 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -605,6 +605,7 @@ bool CNode::ReceiveMsgBytes(const char *pch, unsigned int nBytes, bool& complete
         // absorb network data
         int handled = m_deserializer->Read(pch, nBytes);
         if (handled < 0) {
+            // Serious header problem, disconnect from the peer.
             return false;
         }
 
@@ -616,6 +617,7 @@ bool CNode::ReceiveMsgBytes(const char *pch, unsigned int nBytes, bool& complete
             uint32_t out_err_raw_size{0};
             Optional<CNetMessage> result{m_deserializer->GetMessage(time, out_err_raw_size)};
             if (!result) {
+                // Message deserialization failed.  Drop the message but don't disconnect the peer.
                 // store the size of the corrupt message
                 mapRecvBytesPerMsgCmd.find(NET_MESSAGE_COMMAND_OTHER)->second += out_err_raw_size;
                 continue;
@@ -657,11 +659,19 @@ int V1TransportDeserializer::readHeader(const char *pch, unsigned int nBytes)
         hdrbuf >> hdr;
     }
     catch (const std::exception&) {
+        LogPrint(BCLog::NET, "HEADER ERROR - UNABLE TO DESERIALIZE, peer=%d\n", m_node_id);
+        return -1;
+    }
+
+    // Check start string, network magic
+    if (memcmp(hdr.pchMessageStart, m_chain_params.MessageStart(), CMessageHeader::MESSAGE_START_SIZE) != 0) {
+        LogPrint(BCLog::NET, "HEADER ERROR - MESSAGESTART (%s, %u bytes), received %s, peer=%d\n", hdr.GetCommand(), hdr.nMessageSize, HexStr(hdr.pchMessageStart), m_node_id);
         return -1;
     }
 
     // reject messages larger than MAX_SIZE or MAX_PROTOCOL_MESSAGE_LENGTH
     if (hdr.nMessageSize > MAX_SIZE || hdr.nMessageSize > MAX_PROTOCOL_MESSAGE_LENGTH) {
+        LogPrint(BCLog::NET, "HEADER ERROR - SIZE (%s, %u bytes), peer=%d\n", hdr.GetCommand(), hdr.nMessageSize, m_node_id);
         return -1;
     }
 
@@ -701,10 +711,6 @@ Optional<CNetMessage> V1TransportDeserializer::GetMessage(const std::chrono::mic
     // decompose a single CNetMessage from the TransportDeserializer
     Optional<CNetMessage> msg(std::move(vRecv));
 
-    // store state about valid header, netmagic and checksum
-    msg->m_valid_header = hdr.IsValid(m_chain_params.MessageStart());
-    msg->m_valid_netmagic = (memcmp(hdr.pchMessageStart, m_chain_params.MessageStart(), CMessageHeader::MESSAGE_START_SIZE) == 0);
-
     // store command string, time, and sizes
     msg->m_command = hdr.GetCommand();
     msg->m_time = time;
@@ -716,6 +722,7 @@ Optional<CNetMessage> V1TransportDeserializer::GetMessage(const std::chrono::mic
     // We just received a message off the wire, harvest entropy from the time (and the message checksum)
     RandAddEvent(ReadLE32(hash.begin()));
 
+    // Check checksum and header command string
     if (memcmp(hash.begin(), hdr.pchChecksum, CMessageHeader::CHECKSUM_SIZE) != 0) {
         LogPrint(BCLog::NET, "CHECKSUM ERROR (%s, %u bytes), expected %s was %s, peer=%d\n",
                  SanitizeString(msg->m_command), msg->m_message_size,
@@ -724,6 +731,11 @@ Optional<CNetMessage> V1TransportDeserializer::GetMessage(const std::chrono::mic
                  m_node_id);
         out_err_raw_size = msg->m_raw_message_size;
         msg = nullopt;
+    } else if (!hdr.IsCommandValid()) {
+        LogPrint(BCLog::NET, "HEADER ERROR - COMMAND (%s, %u bytes), peer=%d\n",
+                 hdr.GetCommand(), msg->m_message_size, m_node_id);
+        out_err_raw_size = msg->m_raw_message_size;
+        msg = nullopt;
     }
 
     // Always reset the network deserializer (prepare for the next message)