Merge bitcoin/bitcoin#24213: refactor: use Span in random.*

3ae7791bcaa88f5c68592673b8926ee807242ce7 refactor: use Span in random.* (pasta)

Pull request description:

  ~This PR does two things~
  1. use a Span<unsigned char> for GetRandBytes and GetStrongRandBytes

  ~2. make GetRand a template for which any integral type can be used, where the default behavior is to return a random integral up to the max of the integral unless a max is provided.
  This simplifies a lot of code from `GetRand(std::numeric_limits<uint64_t>::max()` -> `GetRand<uint64_t>()`~

  MarcoFalke this was inspired by your comment here: https://github.com/bitcoin/bitcoin/pull/24185#issuecomment-1025514263 about using Span, so hopefully I'll be able to get this PR done and merged 😂

  ~Also, if requested I could revert the `GetRand(std::numeric_limits<uint64_t>::max()` -> `GetRand<uint64_t>()` related changes if it ends up causing too many conflicts~

ACKs for top commit:
  laanwj:
    Thank you! Code review re-ACK 3ae7791bcaa88f5c68592673b8926ee807242ce7

Tree-SHA512: 12375a83b68b288916ba0de81cfcab4aac14389a66a36811ae850427435eb67dd55e47df9ac3ec47db4e214f4330139e548bec815fff8a3f571484ea558dca79

1 files changed, 4 insertions, 3 deletions

diff --git a/src/random.cpp b/src/random.cpp
index 77d2ae4d43..6ae08103b1 100644
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -16,6 +16,7 @@
 #include <logging.h>
 #include <randomenv.h>
 #include <support/allocators/secure.h>
+#include <span.h>
 #include <sync.h>     // for Mutex
 #include <util/time.h> // for GetTimeMicros()
 
@@ -578,8 +579,8 @@ static void ProcRand(unsigned char* out, int num, RNGLevel level) noexcept
     }
 }
 
-void GetRandBytes(unsigned char* buf, int num) noexcept { ProcRand(buf, num, RNGLevel::FAST); }
-void GetStrongRandBytes(unsigned char* buf, int num) noexcept { ProcRand(buf, num, RNGLevel::SLOW); }
+void GetRandBytes(Span<unsigned char> bytes) noexcept { ProcRand(bytes.data(), bytes.size(), RNGLevel::FAST); }
+void GetStrongRandBytes(Span<unsigned char> bytes) noexcept { ProcRand(bytes.data(), bytes.size(), RNGLevel::SLOW); }
 void RandAddPeriodic() noexcept { ProcRand(nullptr, 0, RNGLevel::PERIODIC); }
 void RandAddEvent(const uint32_t event_info) noexcept { GetRNGState().AddEvent(event_info); }
 
@@ -598,7 +599,7 @@ int GetRandInt(int nMax) noexcept
 uint256 GetRandHash() noexcept
 {
     uint256 hash;
-    GetRandBytes((unsigned char*)&hash, sizeof(hash));
+    GetRandBytes(hash);
     return hash;
 }