Added support for IP address computation

src/engine.rs

@@ -1,7 +1,9 @@
+use std::fmt::{Display, Formatter};
 use std::future::Future;
-use mlua::{FromLua, IntoLua, Lua, UserData, UserDataFields, Value};
-use std::net::{IpAddr, Ipv4Addr, SocketAddr};
+use mlua::{FromLua, FromLuaMulti, IntoLua, Lua, UserData, UserDataFields, UserDataMethods, Value};
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
 use std::path::PathBuf;
+use std::str::FromStr;
 use anyhow::anyhow;
 use async_tftp::packet::Error;
 
@@ -26,6 +28,17 @@ pub enum Resource {
     Error(Error)
 }
 
+impl Display for Resource {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Resource::Http(url) => write!(f, "HTTP {url}"),
+            Resource::File(path) => write!(f, "FILE {path}"),
+            Resource::Data(data) => write!(f, "DATA ({} bytes)", data.len()),
+            Resource::Error(err) => write!(f, "ERR {err:?}")
+        }
+    }
+}
+
 impl Resource {
 }
 
@@ -34,7 +47,7 @@ impl UserData for Resource {
 }
 
 impl<'lua> FromLua<'lua> for Resource {
-    fn from_lua(value: Value<'lua>, _lua: &'lua Lua) -> mlua::Result<Self> {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> mlua::Result<Self> {
         value.as_userdata().ok_or(mlua::Error::UserDataTypeMismatch).and_then(|value| value.take())
     }
 }
@@ -67,16 +80,228 @@ pub struct EngineImpl {
     chan: Option<tokio::sync::mpsc::Receiver<EngineReq>>,
 }
 
+#[derive(Copy, Clone)]
+struct Cidr {
+    addr: IpAddr,
+    prefix: u8,
+}
+
+impl Display for Cidr {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}/{}", self.addr, self.prefix)
+    }
+}
+
+impl Cidr {
+    fn to_v6(&self) -> Self {
+        match self.addr {
+            IpAddr::V4(ip) => Cidr {
+                addr: IpAddr::V6(ip.to_ipv6_mapped()),
+                prefix: self.prefix + 96,
+            },
+            IpAddr::V6(_) => *self,
+        }
+    }
+}
+
+#[repr(transparent)]
+#[derive(Copy, Clone)]
+struct IpAddrWrapper(IpAddr);
+
+impl IpAddrWrapper {
+    fn octet_len(&self) -> usize {
+        match &self.0 {
+            IpAddr::V4(_) => 4,
+            IpAddr::V6(_) => 16,
+        }
+    }
+
+    fn to_v6(&self) -> Ipv6Addr {
+        match self.0 {
+            IpAddr::V4(v4) => v4.to_ipv6_mapped(),
+            IpAddr::V6(v6) => v6
+        }
+    }
+}
+
+impl UserData for IpAddrWrapper {
+    fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+        fields.add_field_method_get("version", |_, ip| Ok(if ip.0.is_ipv4() { 4} else {6}));
+        fields.add_field_method_get("is_ipv4", |_, ip| Ok(ip.0.is_ipv4()));
+        fields.add_field_method_get("is_ipv6", |_, ip| Ok(ip.0.is_ipv6()));
+        fields.add_field_method_get("bytes", |lua, ip| match &ip.0 {
+            IpAddr::V4(v4) => lua.create_string(v4.octets()),
+            IpAddr::V6(v6) => lua.create_string(v6.octets()),
+        });
+        fields.add_meta_field("__name", "IpAddr");
+    }
+
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_method("to_v6", |_, ip, ()| match &ip.0 {
+            IpAddr::V4(v4) => Ok(IpAddrWrapper(IpAddr::V6(v4.to_ipv6_mapped()))),
+            IpAddr::V6(v6) => Ok(IpAddrWrapper(IpAddr::V6(*v6))),
+        });
+        methods.add_meta_method("__index", |_, ip, index: usize| match &ip.0 {
+            IpAddr::V4(ip) if 1 <= index && index <= 4 => Ok(ip.octets()[index-1]),
+            IpAddr::V6(ip) if 1 <= index && index <= 16 => Ok(ip.octets()[index-1]),
+            _ => Err(mlua::Error::runtime("Index out of range")),
+        });
+        methods.add_meta_method_mut("__newindex", |_, ip, (index, value): (usize, u8)| {
+            match &mut ip.0 {
+                IpAddr::V4(ip) if 1 <= index && index <= 4 => {
+                    let mut octets = ip.octets();
+                    octets[index-1] = value;
+                    IpAddr::V4(octets.into());
+                },
+                IpAddr::V6(ip) if 1 <= index && index <= 16 => {
+                    let mut octets = ip.octets();
+                    octets[index-1] = value;
+                    IpAddr::V6(octets.into());
+                },
+                _ => return Err(mlua::Error::runtime("Index out of range")),
+            };
+            Ok(())
+        });
+        methods.add_meta_method("__tostring", |_, ip, ()|  Ok(ip.0.to_string()));
+        methods.add_meta_function("__call", |lua, args: mlua::MultiValue| Ok(IpAddrWrapper({
+            eprintln!("IpAddr __call Received {} args", args.len());
+            if args.len() == 4 {
+                // IPV4 direct bytes
+                let (a,b,c,d) = <(u8,u8,u8,u8)>::from_lua_args(args, 0, Some("sftpd.IpAddr"), lua)?;
+                IpAddr::V4([a,b,c,d].into())
+            } else if args.len() == 16 {
+                let mut octets = [0u8;16];
+                for i in 0..16 {
+                    octets[i] = u8::from_lua(args.get(i).unwrap().clone(), lua)?;
+                }
+                IpAddr::V6(octets.into())
+            } else if args.len() == 1 {
+                return IpAddrWrapper::from_lua(args[0].clone(), lua);
+            } else {
+                return Err(mlua::Error::runtime("Invalid arguments to stfptd.IpAddr"))
+            }
+        })));
+        methods.add_meta_method("__eq", |_, me, other: IpAddrWrapper| Ok(me.to_v6() == other.to_v6()))
+    }
+}
+
+impl<'lua> FromLua<'lua> for IpAddrWrapper {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> mlua::Result<Self> {
+        return if let Some(ud) = value.as_userdata() {
+            Ok(ud.borrow::<IpAddrWrapper>()?.clone())
+        } else if let Some(s) = value.as_str() {
+            IpAddr::from_str(s)
+                .map(IpAddrWrapper)
+                .map_err(mlua::Error::external)
+        } else {
+            Err(mlua::Error::FromLuaConversionError {
+                from: value.type_name(),
+                to: "IpAddr",
+                message: None,
+            })
+        }
+    }
+}
+
+impl UserData for Cidr {
+    fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+        fields.add_field_method_get("addr", |_lua, cidr| Ok(IpAddrWrapper(cidr.addr)));
+        fields.add_field_method_set("addr", |_lua, cidr, value: IpAddrWrapper| {
+            if cidr.addr.is_ipv4() ^ value.0.is_ipv4() {
+                return Err(mlua::Error::runtime(format!(
+                    "Cannot assign v{} addr to v{} CIDR",
+                    if value.0.is_ipv4() { 4 } else { 6 },
+                    if cidr.addr.is_ipv4() { 4 } else { 6 },
+                )));
+            }
+            cidr.addr = value.0;
+            Ok(())
+        });
+        fields.add_field_method_get("prefix", |_lua, cidr| Ok(cidr.prefix));
+        fields.add_field_method_set("prefix", |_lua, cidr, value: u8| {
+            if value >= if cidr.addr.is_ipv4() { 32 } else { 128 } {
+                return Err(mlua::Error::runtime("Invalid prefix length"));
+            }
+            cidr.prefix = value;
+            Ok(())
+        });
+    }
+
+    fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_method("contains", |_, cidr, addr: IpAddrWrapper| {
+            let addr = u128::from_be_bytes(addr.to_v6().octets());
+            let cidr = cidr.to_v6();
+            if cidr.prefix == 0 {
+                // Global network
+                return Ok(true)
+            }
+            let mask = (!0u128) << (128 - cidr.prefix);
+            let network = u128::from_be_bytes(IpAddrWrapper(cidr.addr).to_v6().octets());
+
+            Ok(addr & mask == network & mask)
+        });
+
+        methods.add_meta_method("__tostring", |_, cidr, ()| Ok(cidr.to_string()));
+        methods.add_meta_method("__eq", |_, cidr, other: Cidr| {
+            let cidr = cidr.to_v6();
+            let other = other.to_v6();
+            Ok(cidr.prefix == other.prefix && cidr.addr == other.addr)
+        });
+
+        methods.add_meta_function("__call", |lua, args: mlua::MultiValue| {
+            if args.len() == 0 {
+                Ok(Cidr{addr: IpAddr::V6(Ipv6Addr::UNSPECIFIED), prefix: 0})
+            } else if args.len() == 1 {
+                Cidr::from_lua_args(args, 0, Some("stftpd.Cidr"), lua)
+            } else {
+                let (IpAddrWrapper(addr), prefix) = <(IpAddrWrapper, u8)>::from_lua_args(args, 0, Some("stftpd.Cidr"), lua)?;
+                let max_prefix = if addr.is_ipv4() { 32 } else { 64 };
+                if prefix > max_prefix {
+                    return Err(mlua::Error::runtime("Invalid prefix"));
+                }
+                Ok(Cidr{addr, prefix})
+            }
+        });
+    }
+}
+
+impl<'lua> FromLua<'lua> for Cidr {
+    fn from_lua(value: Value<'lua>, _: &'lua Lua) -> mlua::Result<Self> {
+        return if let Some(ud) = value.as_userdata() {
+            Ok(ud.borrow::<Cidr>()?.clone())
+        } else if let Some(s) = value.as_str() {
+            let (addr, prefix) = s.split_once("/")
+                .map(|(a,p)| (a,Some(p)))
+                .unwrap_or((s, None));
+            let addr = IpAddr::from_str(addr)?;
+            let prefix = prefix.map(u8::from_str)
+                .transpose()
+                .map_err(mlua::Error::external)?;
+
+            let max_prefix = if addr.is_ipv4() { 32 } else { 128 };
+            let prefix = prefix.unwrap_or(max_prefix);
+            if prefix > max_prefix {
+                return Err(mlua::Error::runtime("CIDR prefix to long"))
+            }
+
+            Ok(Cidr {
+                addr, prefix
+            })
+        } else {
+            Err(mlua::Error::FromLuaConversionError {
+                from: value.type_name(),
+                to: "Cidr",
+                message: None,
+            })
+        }
+    }
+}
+
 impl EngineImpl {
     pub(crate) fn init(&mut self) -> anyhow::Result<()> {
         let lua = &* self.lua;
         lua.load_from_std_lib(mlua::StdLib::ALL)?;
 
-
-        lua.register_userdata_type::<IpAddr>(|registry| {
-            registry.add_field_method_get("version", |_, ip| Ok(if ip.is_ipv4() { 4} else {6}));
-        })?;
-
         {
             // prepare resource types...
             let resources = lua.create_table()?;
@@ -98,11 +323,19 @@ impl EngineImpl {
             err_tbl.set("FileAlreadyExists", Resource::Error(Error::FileAlreadyExists))?;
             err_tbl.set("NoSuchUser", Resource::Error(Error::NoSuchUser))?;
             err_tbl.set("Message", err_fn)?;
+            err_tbl.set_readonly(true);
 
             resources.set("ERROR", err_tbl)?;
+            resources.set_readonly(true);
+
             lua.globals().set("resource", resources)?;
             lua.globals().set("state", lua.create_table()?)?;
 
+            // Construct data types
+            let stftpd = lua.create_table()?;
+            stftpd.set("Cidr", lua.create_proxy::<Cidr>()?)?;
+            stftpd.set("IpAddr", lua.create_proxy::<IpAddrWrapper>()?)?;
+
             //
         }