1 files changed, 109 insertions, 0 deletions
diff --git a/third_party/rust/neqo-transport/src/path.rs b/third_party/rust/neqo-transport/src/path.rs
new file mode 100644
index 0000000000..a4e6b2f361
--- /dev/null
+++ b/third_party/rust/neqo-transport/src/path.rs
@@ -0,0 +1,109 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::net::SocketAddr;
+
+use crate::cid::{ConnectionId, ConnectionIdRef};
+
+use neqo_common::Datagram;
+
+/// This is the MTU that we assume when using IPv6.
+/// We use this size for Initial packets, so we don't need to worry about probing for support.
+/// If the path doesn't support this MTU, we will assume that it doesn't support QUIC.
+///
+/// This is a multiple of 16 greater than the largest possible short header (1 + 20 + 4).
+pub const PATH_MTU_V6: usize = 1337;
+/// The path MTU for IPv4 can be 20 bytes larger than for v6.
+pub const PATH_MTU_V4: usize = PATH_MTU_V6 + 20;
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Path {
+    local: SocketAddr,
+    remote: SocketAddr,
+    local_cids: Vec<ConnectionId>,
+    remote_cid: ConnectionId,
+    reset_token: Option<[u8; 16]>,
+}
+
+impl Path {
+    /// Create a path from addresses and connection IDs.
+    pub fn new(
+        local: SocketAddr,
+        remote: SocketAddr,
+        local_cid: ConnectionId,
+        remote_cid: ConnectionId,
+    ) -> Self {
+        Self {
+            local,
+            remote,
+            local_cids: vec![local_cid],
+            remote_cid,
+            reset_token: None,
+        }
+    }
+
+    pub fn received_on(&self, d: &Datagram) -> bool {
+        self.local == d.destination() && self.remote == d.source()
+    }
+
+    pub fn mtu(&self) -> usize {
+        if self.local.is_ipv4() {
+            PATH_MTU_V4
+        } else {
+            PATH_MTU_V6 // IPv6
+        }
+    }
+
+    /// Add a connection ID to the local set.
+    pub fn add_local_cid(&mut self, cid: ConnectionId) {
+        self.local_cids.push(cid);
+    }
+
+    /// Determine if the given connection ID is valid.
+    pub fn valid_local_cid(&self, cid: &ConnectionIdRef) -> bool {
+        self.local_cids.iter().any(|c| c == cid)
+    }
+
+    /// Get the first local connection ID.
+    pub fn local_cid(&self) -> &ConnectionId {
+        self.local_cids.first().as_ref().unwrap()
+    }
+
+    /// Set the remote connection ID based on the peer's choice.
+    pub fn set_remote_cid(&mut self, cid: &ConnectionIdRef) {
+        self.remote_cid = ConnectionId::from(cid);
+    }
+
+    /// Access the remote connection ID.
+    pub fn remote_cid(&self) -> &ConnectionId {
+        &self.remote_cid
+    }
+
+    /// Set the stateless reset token for the connection ID that is currently in use.
+    pub fn set_reset_token(&mut self, token: [u8; 16]) {
+        self.reset_token = Some(token);
+    }
+
+    /// Access the reset token.
+    pub fn reset_token(&self) -> Option<&[u8; 16]> {
+        self.reset_token.as_ref()
+    }
+
+    /// Make a datagram.
+    pub fn datagram<V: Into<Vec<u8>>>(&self, payload: V) -> Datagram {
+        Datagram::new(self.local, self.remote, payload)
+    }
+
+    /// Get local address as `SocketAddr`
+    pub fn local_address(&self) -> SocketAddr {
+        self.local
+    }
+
+    /// Get remote address as `SocketAddr`
+    pub fn remote_address(&self) -> SocketAddr {
+        self.remote
+    }
+}