Merge bitcoin#21939: refactor: Replace memset calls with array initialization

1c9255c refactor: Replace memset calls with array initialization (João Barbosa)

Pull request description:

  Follow up to bitcoin#21905 (review).

ACKs for top commit:
  laanwj:
    re-ACK 1c9255c
  Crypt-iQ:
    Code review ACK 1c9255c

Tree-SHA512: 4b61dec2094f4781ef1c0427ee3bda3cfea12111274eebc7bc40a84f261d9c1681dd0860c57200bea2456588e44e8e0aecd18545c25f1f1250dd331ab7d05f28

Author: laanwj

src/protocol.cpp

@@ -202,25 +202,16 @@ const static std::string netMessageTypesViolateBlocksOnly[] = {
 };
 const static std::set<std::string> netMessageTypesViolateBlocksOnlySet(std::begin(netMessageTypesViolateBlocksOnly), std::end(netMessageTypesViolateBlocksOnly));
 
-CMessageHeader::CMessageHeader()
-{
-    memset(pchMessageStart, 0, MESSAGE_START_SIZE);
-    memset(pchCommand, 0, sizeof(pchCommand));
-    memset(pchChecksum, 0, CHECKSUM_SIZE);
-}
-
 CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn, const char* pszCommand, unsigned int nMessageSizeIn)
 {
     memcpy(pchMessageStart, pchMessageStartIn, MESSAGE_START_SIZE);
 
-    // Copy the command name, zero-padding to COMMAND_SIZE bytes
+    // Copy the command name
     size_t i = 0;
     for (; i < COMMAND_SIZE && pszCommand[i] != 0; ++i) pchCommand[i] = pszCommand[i];
     assert(pszCommand[i] == 0); // Assert that the command name passed in is not longer than COMMAND_SIZE
-    for (; i < COMMAND_SIZE; ++i) pchCommand[i] = 0;
 
     nMessageSize = nMessageSizeIn;
-    memset(pchChecksum, 0, CHECKSUM_SIZE);
 }
 
 std::string CMessageHeader::GetCommand() const

src/protocol.h

@@ -39,7 +39,7 @@ class CMessageHeader
     static constexpr size_t HEADER_SIZE = MESSAGE_START_SIZE + COMMAND_SIZE + MESSAGE_SIZE_SIZE + CHECKSUM_SIZE;
     typedef unsigned char MessageStartChars[MESSAGE_START_SIZE];
 
-    explicit CMessageHeader();
+    explicit CMessageHeader() = default;
 
     /** Construct a P2P message header from message-start characters, a command and the size of the message.
      * @note Passing in a `pszCommand` longer than COMMAND_SIZE will result in a run-time assertion error.
@@ -51,10 +51,10 @@ class CMessageHeader
 
     SERIALIZE_METHODS(CMessageHeader, obj) { READWRITE(obj.pchMessageStart, obj.pchCommand, obj.nMessageSize, obj.pchChecksum); }
 
-    char pchMessageStart[MESSAGE_START_SIZE];
-    char pchCommand[COMMAND_SIZE];
+    char pchMessageStart[MESSAGE_START_SIZE]{};
+    char pchCommand[COMMAND_SIZE]{};
     uint32_t nMessageSize{std::numeric_limits<uint32_t>::max()};
-    uint8_t pchChecksum[CHECKSUM_SIZE];
+    uint8_t pchChecksum[CHECKSUM_SIZE]{};
 };
 
 /**