net: allow CSubNet of non-IP networks

Allow creation of valid `CSubNet` objects of non-IP networks and only
match the single address they were created from (like /32 for IPv4 or
/128 for IPv6).

This fixes a deficiency in `CConnman::DisconnectNode(const CNetAddr& addr)`
and in `BanMan` which assume that creating a subnet from any address
using the `CSubNet(CNetAddr)` constructor would later match that address
only. Before this change a non-IP subnet would be invalid and would not
match any address.

1 files changed, 23 insertions, 1 deletions

diff --git a/src/netaddress.h b/src/netaddress.h
index 29b2eaafeb..b9beb1e358 100644
--- a/src/netaddress.h
+++ b/src/netaddress.h
@@ -462,11 +462,33 @@ class CSubNet
         bool SanityCheck() const;
 
     public:
+        /**
+         * Construct an invalid subnet (empty, `Match()` always returns false).
+         */
         CSubNet();
+
+        /**
+         * Construct from a given network start and number of bits (CIDR mask).
+         * @param[in] addr Network start. Must be IPv4 or IPv6, otherwise an invalid subnet is
+         * created.
+         * @param[in] mask CIDR mask, must be in [0, 32] for IPv4 addresses and in [0, 128] for
+         * IPv6 addresses. Otherwise an invalid subnet is created.
+         */
         CSubNet(const CNetAddr& addr, uint8_t mask);
+
+        /**
+         * Construct from a given network start and mask.
+         * @param[in] addr Network start. Must be IPv4 or IPv6, otherwise an invalid subnet is
+         * created.
+         * @param[in] mask Network mask, must be of the same type as `addr` and not contain 0-bits
+         * followed by 1-bits. Otherwise an invalid subnet is created.
+         */
         CSubNet(const CNetAddr& addr, const CNetAddr& mask);
 
-        //constructor for single ip subnet (<ipv4>/32 or <ipv6>/128)
+        /**
+         * Construct a single-host subnet.
+         * @param[in] addr The sole address to be contained in the subnet, can also be non-IPv[46].
+         */
         explicit CSubNet(const CNetAddr& addr);
 
         bool Match(const CNetAddr &addr) const;