Merge bitcoin/bitcoin#28857: test, refactor: Magic bytes array followup

1e5b861 test: Add test for array serialization (TheCharlatan)
d49d198 refactor: Initialize magic bytes in constructor initializer (TheCharlatan)

Pull request description:

  This is a followup-PR for #28423

  * Initialize magic bytes in constructor
  * Add a small unit test for serializing arrays.

ACKs for top commit:
  sipa:
    utACK 1e5b861
  maflcko:
    lgtm ACK 1e5b861

Tree-SHA512: 0f58d2332dc501ca9fd419f40ed4f977c83dce0169e9a0eee1ffc9f8daa2d2ef7e7df18205ba076f55d90ae6c4a20d2b51ab303150d38470a962bcc58a66f6e7

Author: fanquake

src/net.cpp

@@ -684,10 +684,8 @@ bool CNode::ReceiveMsgBytes(Span<const uint8_t> msg_bytes, bool& complete)
 }
 
 V1Transport::V1Transport(const NodeId node_id, int nTypeIn, int nVersionIn) noexcept :
-    m_node_id(node_id), hdrbuf(nTypeIn, nVersionIn), vRecv(nTypeIn, nVersionIn)
+    m_magic_bytes{Params().MessageStart()}, m_node_id(node_id), hdrbuf(nTypeIn, nVersionIn), vRecv(nTypeIn, nVersionIn)
 {
-    assert(std::size(Params().MessageStart()) == std::size(m_magic_bytes));
-    m_magic_bytes = Params().MessageStart();
     LOCK(m_recv_mutex);
     Reset();
 }

src/net.h

@@ -372,7 +372,7 @@ class Transport {
 class V1Transport final : public Transport
 {
 private:
-    MessageStartChars m_magic_bytes;
+    const MessageStartChars m_magic_bytes;
     const NodeId m_node_id; // Only for logging
     mutable Mutex m_recv_mutex; //!< Lock for receive state
     mutable CHash256 hasher GUARDED_BY(m_recv_mutex);

src/protocol.cpp

@@ -91,9 +91,8 @@ const static std::vector<std::string> g_all_net_message_types{
 };
 
 CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn, const char* pszCommand, unsigned int nMessageSizeIn)
+    : pchMessageStart{pchMessageStartIn}
 {
-    pchMessageStart = pchMessageStartIn;
-
     // Copy the command name
     size_t i = 0;
     for (; i < COMMAND_SIZE && pszCommand[i] != 0; ++i) pchCommand[i] = pszCommand[i];

src/test/serialize_tests.cpp

@@ -85,6 +85,8 @@ BOOST_AUTO_TEST_CASE(sizes)
     BOOST_CHECK_EQUAL(GetSerializeSize(int64_t(0), 0), 8U);
     BOOST_CHECK_EQUAL(GetSerializeSize(uint64_t(0), 0), 8U);
     BOOST_CHECK_EQUAL(GetSerializeSize(bool(0), 0), 1U);
+    BOOST_CHECK_EQUAL(GetSerializeSize(std::array<uint8_t, 1>{0}, 0), 1U);
+    BOOST_CHECK_EQUAL(GetSerializeSize(std::array<uint8_t, 2>{0, 0}, 0), 2U);
 }
 
 BOOST_AUTO_TEST_CASE(varints)
@@ -179,6 +181,16 @@ BOOST_AUTO_TEST_CASE(vector_bool)
     BOOST_CHECK((HashWriter{} << vec1).GetHash() == (HashWriter{} << vec2).GetHash());
 }
 
+BOOST_AUTO_TEST_CASE(array)
+{
+    std::array<uint8_t, 32> array1{1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1};
+    DataStream ds;
+    ds << array1;
+    std::array<uint8_t, 32> array2;
+    ds >> array2;
+    BOOST_CHECK(array1 == array2);
+}
+
 BOOST_AUTO_TEST_CASE(noncanonical)
 {
     // Write some non-canonical CompactSize encodings, and