Remove header checks out of net_processing

This moves header size and netmagic checking out of net_processing and
into net.  This check now runs in ReadHeader, so that net can exit early
out of receiving bytes from the peer.  IsValid is now slimmed down, so
it no longer needs a MessageStartChars& parameter.

Additionally this removes the rest of the m_valid_* members from
CNetMessage.

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)