add: ban ipv6 addresses by prefix

assumes all ipv6 addresses have 64-bit prefix (8 bytes at the start + 2 bytes for colons)

crates/core/src/model/addr.rs

@@ -0,0 +1,61 @@
+use std::net::SocketAddr;
+
+/// How many bytes should be chopped off the end of an IPV6 address to get its prefix.
+pub(crate) const IPV6_PREFIX_BYTES: usize = 8;
+
+/// The protocol of a [`RemoteAddr`].
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum AddrProto {
+    IPV4,
+    IPV6,
+}
+
+/// A representation of a remote IP address.
+#[derive(Clone, Debug)]
+pub struct RemoteAddr(pub SocketAddr, pub AddrProto);
+
+impl From<&str> for RemoteAddr {
+    fn from(value: &str) -> Self {
+        if value.len() >= 16 {
+            // ipv6 (16 bytes; 128 bits)
+            if !(value.starts_with("[") | value.contains("]:1000")) {
+                Self(format!("[{value}]:1000").parse().unwrap(), AddrProto::IPV6)
+            } else {
+                Self(value.parse().unwrap(), AddrProto::IPV6)
+            }
+        } else {
+            // ipv4 (4 bytes; 32 bits)
+            Self(value.parse().unwrap(), AddrProto::IPV4)
+        }
+    }
+}
+
+impl RemoteAddr {
+    /// Get the address' prefix (returns the entire address for IPV4 addresses).
+    ///
+    ///  Operates on the IP address **without** colon characters.
+    pub fn prefix(&self, chop: Option<usize>) -> String {
+        if self.1 == AddrProto::IPV4 {
+            return self.0.to_string();
+        }
+
+        // we're adding 2 bytes to the chop bytes because we also
+        // need to remove 2 colons
+        let as_string = self.ipv6_inner();
+        (&as_string[0..(match chop {
+            Some(c) => c,
+            None => IPV6_PREFIX_BYTES,
+        } + (IPV6_PREFIX_BYTES / 4))])
+            .to_string()
+    }
+
+    /// [`Self::prefix`], but it returns another [`RemoteAddr`].
+    pub fn to_prefix(self, chop: Option<usize>) -> Self {
+        Self::from(self.prefix(chop).as_str())
+    }
+
+    /// Get the innter content from the address (as ipv6).
+    pub fn ipv6_inner(&self) -> String {
+        self.0.to_string().replace("[", "").replace("]:1000", "")
+    }
+}

crates/core/src/model/mod.rs

@@ -1,3 +1,4 @@
+pub mod addr;
 pub mod auth;
 pub mod communities;
 pub mod communities_permissions;