[WIP] 0.3.0 mtp update

iota-util/src/route_target.rs

@@ -0,0 +1,44 @@
+const TARGET_KIND_MASK: u64 = 0xC000_0000_0000_0000;
+const TARGET_ID_MASK: u64 = (1_u64 << 48) - 1;
+const USER_TARGET_KIND: u64 = 0x4000_0000_0000_0000;
+const IOTA_TARGET_KIND: u64 = 0x8000_0000_0000_0000;
+
+/*
+ * Relay receivers carry their namespace in the wire identity. This prevents
+ * a user ID and an Iota ID with the same numeric value from selecting the
+ * wrong connection at an Omikron.
+ */
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum RouteTarget {
+    User(u64),
+    Iota(u64),
+}
+
+impl RouteTarget {
+    pub fn wire_id(self) -> Option<u64> {
+        let (kind, id) = match self {
+            Self::User(id) => (USER_TARGET_KIND, id),
+            Self::Iota(id) => (IOTA_TARGET_KIND, id),
+        };
+        (id > 0 && id <= TARGET_ID_MASK).then_some(kind | id)
+    }
+
+    pub fn from_wire_id(value: u64) -> Option<Self> {
+        let id = value & TARGET_ID_MASK;
+        if id == 0 || value & !(TARGET_KIND_MASK | TARGET_ID_MASK) != 0 {
+            return None;
+        }
+
+        match value & TARGET_KIND_MASK {
+            USER_TARGET_KIND => Some(Self::User(id)),
+            IOTA_TARGET_KIND => Some(Self::Iota(id)),
+            _ => None,
+        }
+    }
+
+    pub const fn id(self) -> u64 {
+        match self {
+            Self::User(id) | Self::Iota(id) => id,
+        }
+    }
+}