protocol.h: Move MESSAGE_START_SIZE into CMessageHeader

Also move the enum to the top, and remove a deceptive TODO
comment.

src/main.cpp

@@ -4358,11 +4358,11 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
             unsigned int nSize = 0;
             try {
                 // locate a header
-                unsigned char buf[MESSAGE_START_SIZE];
+                unsigned char buf[CMessageHeader::MESSAGE_START_SIZE];
                 blkdat.FindByte(chainparams.MessageStart()[0]);
                 nRewind = blkdat.GetPos()+1;
                 blkdat >> FLATDATA(buf);
-                if (memcmp(buf, chainparams.MessageStart(), MESSAGE_START_SIZE))
+                if (memcmp(buf, chainparams.MessageStart(), CMessageHeader::MESSAGE_START_SIZE))
                     continue;
                 // read size
                 blkdat >> nSize;
@@ -6232,7 +6232,7 @@ bool ProcessMessages(CNode* pfrom, CConnman& connman)
         it++;
 
         // Scan for message start
-        if (memcmp(msg.hdr.pchMessageStart, chainparams.MessageStart(), MESSAGE_START_SIZE) != 0) {
+        if (memcmp(msg.hdr.pchMessageStart, chainparams.MessageStart(), CMessageHeader::MESSAGE_START_SIZE) != 0) {
             LogPrintf("PROCESSMESSAGE: INVALID MESSAGESTART %s peer=%d\n", SanitizeString(msg.hdr.GetCommand()), pfrom->id);
             fOk = false;
             break;

src/protocol.h

@@ -18,8 +18,6 @@
 #include <stdint.h>
 #include <string>
 
-#define MESSAGE_START_SIZE 4
-
 /** Message header.
  * (4) message start.
  * (12) command.
@@ -29,6 +27,16 @@
 class CMessageHeader
 {
 public:
+    enum {
+        MESSAGE_START_SIZE = 4,
+        COMMAND_SIZE = 12,
+        MESSAGE_SIZE_SIZE = 4,
+        CHECKSUM_SIZE = 4,
+
+        MESSAGE_SIZE_OFFSET = MESSAGE_START_SIZE + COMMAND_SIZE,
+        CHECKSUM_OFFSET = MESSAGE_SIZE_OFFSET + MESSAGE_SIZE_SIZE,
+        HEADER_SIZE = MESSAGE_START_SIZE + COMMAND_SIZE + MESSAGE_SIZE_SIZE + CHECKSUM_SIZE
+    };
     typedef unsigned char MessageStartChars[MESSAGE_START_SIZE];
 
     CMessageHeader(const MessageStartChars& pchMessageStartIn);
@@ -48,17 +56,6 @@ public:
         READWRITE(FLATDATA(pchChecksum));
     }
 
-    // TODO: make private (improves encapsulation)
-public:
-    enum {
-        COMMAND_SIZE = 12,
-        MESSAGE_SIZE_SIZE = 4,
-        CHECKSUM_SIZE = 4,
-
-        MESSAGE_SIZE_OFFSET = MESSAGE_START_SIZE + COMMAND_SIZE,
-        CHECKSUM_OFFSET = MESSAGE_SIZE_OFFSET + MESSAGE_SIZE_SIZE,
-        HEADER_SIZE = MESSAGE_START_SIZE + COMMAND_SIZE + MESSAGE_SIZE_SIZE + CHECKSUM_SIZE
-    };
     char pchMessageStart[MESSAGE_START_SIZE];
     char pchCommand[COMMAND_SIZE];
     uint32_t nMessageSize;