Merge bitcoin/bitcoin#21564: net: Avoid calling getnameinfo when formatting IPv4 addresses in CNetAddr::ToStringIP

58580a827d net: Avoid calling getnameinfo when formatting IPv4 addresses in CNetAddr::ToStringIP (practicalswift)
5858057384 net: Add IPv4ToString (we already have IPv6ToString) (practicalswift)

Pull request description:

  Avoid calling `getnameinfo` when formatting IPv4 addresses in `CNetAddr::ToStringIP`.

ACKs for top commit:
  naumenkogs:
    ACK 58580a827d
  0xB10C:
    ACK 58580a827d
  vasild:
    ACK 58580a827d

Tree-SHA512: 25e3c416acb74908d001baf1cf64c04cbc0d94ce8e7ce5a601f1343062d5d748cb406a3404e6f2b6e7e979c6300b38439e1bfd70ea90ec8c0ec2d7568f09fbcd

src/netaddress.cpp

@@ -551,6 +551,11 @@ enum Network CNetAddr::GetNetwork() const
     return m_net;
 }
 
+static std::string IPv4ToString(Span<const uint8_t> a)
+{
+    return strprintf("%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
+}
+
 static std::string IPv6ToString(Span<const uint8_t> a)
 {
     assert(a.size() == ADDR_IPV6_SIZE);
@@ -571,6 +576,7 @@ std::string CNetAddr::ToStringIP() const
 {
     switch (m_net) {
     case NET_IPV4:
+        return IPv4ToString(m_addr);
     case NET_IPV6: {
         CService serv(*this, 0);
         struct sockaddr_storage sockaddr;
@@ -581,9 +587,6 @@ std::string CNetAddr::ToStringIP() const
                              sizeof(name), nullptr, 0, NI_NUMERICHOST))
                 return std::string(name);
         }
-        if (m_net == NET_IPV4) {
-            return strprintf("%u.%u.%u.%u", m_addr[0], m_addr[1], m_addr[2], m_addr[3]);
-        }
         return IPv6ToString(m_addr);
     }
     case NET_ONION: