[netgroupman] Move asmap checksum calculation to NetGroupManager

Author: jnewbery

src/addrman.cpp

@@ -218,11 +218,7 @@ void AddrManImpl::Serialize(Stream& s_) const
     }
     // Store asmap checksum after bucket entries so that it
     // can be ignored by older clients for backward compatibility.
-    uint256 asmap_checksum;
-    if (m_netgroupman.GetAsmap().size() != 0) {
-        asmap_checksum = SerializeHash(m_netgroupman.GetAsmap());
-    }
-    s << asmap_checksum;
+    s << m_netgroupman.GetAsmapChecksum();
 }
 
 template <typename Stream>
@@ -335,10 +331,7 @@ void AddrManImpl::Unserialize(Stream& s_)
     // If the bucket count and asmap checksum haven't changed, then attempt
     // to restore the entries to the buckets/positions they were in before
     // serialization.
-    uint256 supplied_asmap_checksum;
-    if (m_netgroupman.GetAsmap().size() != 0) {
-        supplied_asmap_checksum = SerializeHash(m_netgroupman.GetAsmap());
-    }
+    uint256 supplied_asmap_checksum{m_netgroupman.GetAsmapChecksum()};
     uint256 serialized_asmap_checksum;
     if (format >= Format::V2_ASMAP) {
         s >> serialized_asmap_checksum;

src/netgroup.cpp

@@ -4,8 +4,16 @@
 
 #include <netgroup.h>
 
+#include <hash.h>
 #include <util/asmap.h>
 
+uint256 NetGroupManager::GetAsmapChecksum() const
+{
+    if (!m_asmap.size()) return {};
+
+    return SerializeHash(m_asmap);
+}
+
 std::vector<unsigned char> NetGroupManager::GetGroup(const CNetAddr& address) const
 {
     std::vector<unsigned char> vchRet;

src/netgroup.h

@@ -6,6 +6,7 @@
 #define BITCOIN_NETGROUP_H
 
 #include <netaddress.h>
+#include <uint256.h>
 
 #include <vector>
 
@@ -22,6 +23,9 @@ class NetGroupManager {
      * exists, since the data is const. */
     const std::vector<bool>& GetAsmap() const { return m_asmap; }
 
+    /** Get a checksum identifying the asmap being used. */
+    uint256 GetAsmapChecksum() const;
+
     /**
      * Get the canonical identifier of the network group for address.
      *