From 1488a4eec6000e0e4cbaf953b587a333149b4139 Mon Sep 17 00:00:00 2001
From: Max Leonard Inden <mail@max-inden.de>
Date: Sun, 26 Jan 2025 18:58:43 +0100
Subject: [PATCH] fix(transport/packet): don't (mutably) borrow data multiple
 times

---
 neqo-transport/src/packet/mod.rs | 48 +++++++++++++++++---------------
 1 file changed, 26 insertions(+), 22 deletions(-)

diff --git a/neqo-transport/src/packet/mod.rs b/neqo-transport/src/packet/mod.rs
index 73b47bccd8..a476b1a655 100644
--- a/neqo-transport/src/packet/mod.rs
+++ b/neqo-transport/src/packet/mod.rs
@@ -563,12 +563,12 @@ pub struct PublicPacket<'a> {
     /// The packet type.
     packet_type: PacketType,
     /// The recovered destination connection ID.
-    dcid: ConnectionIdRef<'a>,
+    dcid: ConnectionId,
     /// The source connection ID, if this is a long header packet.
-    scid: Option<ConnectionIdRef<'a>>,
+    scid: Option<ConnectionId>,
     /// Any token that is included in the packet (Retry always has a token; Initial sometimes
     /// does). This is empty when there is no token.
-    token: &'a [u8],
+    token: Vec<u8>,
     /// The size of the header, not including the packet number.
     header_len: usize,
     /// Protocol version, if present in header.
@@ -624,9 +624,9 @@ impl<'a> PublicPacket<'a> {
     pub fn decode(
         data: &'a mut [u8],
         dcid_decoder: &dyn ConnectionIdDecoder,
-    ) -> Res<(Self, &'a mut [u8])> {
+    ) -> Res<(PublicPacket<'a>, &'a mut [u8])> {
         let mut decoder = Decoder::new(data);
-        let first = Self::opt(decoder.decode_uint::<u8>())?;
+        let first = PublicPacket::opt(decoder.decode_uint::<u8>())?;
 
         if first & 0x80 == PACKET_BIT_SHORT {
             // Conveniently, this also guarantees that there is enough space
@@ -634,17 +634,18 @@ impl<'a> PublicPacket<'a> {
             if decoder.remaining() < SAMPLE_OFFSET + SAMPLE_SIZE {
                 return Err(Error::InvalidPacket);
             }
-            let dcid = Self::opt(dcid_decoder.decode_cid(&mut decoder))?;
+            let dcid = PublicPacket::opt(dcid_decoder.decode_cid(&mut decoder))?.into();
             if decoder.remaining() < SAMPLE_OFFSET + SAMPLE_SIZE {
                 return Err(Error::InvalidPacket);
             }
             let header_len = decoder.offset();
+
             return Ok((
-                Self {
+                PublicPacket {
                     packet_type: PacketType::Short,
                     dcid,
                     scid: None,
-                    token: &[],
+                    token: vec![],
                     header_len,
                     version: None,
                     data,
@@ -654,18 +655,18 @@ impl<'a> PublicPacket<'a> {
         }
 
         // Generic long header.
-        let version = Self::opt(decoder.decode_uint())?;
-        let dcid = ConnectionIdRef::from(Self::opt(decoder.decode_vec(1))?);
-        let scid = ConnectionIdRef::from(Self::opt(decoder.decode_vec(1))?);
+        let version = PublicPacket::opt(decoder.decode_uint())?;
+        let dcid = ConnectionIdRef::from(PublicPacket::opt(decoder.decode_vec(1))?).into();
+        let scid = ConnectionIdRef::from(PublicPacket::opt(decoder.decode_vec(1))?).into();
 
         // Version negotiation.
         if version == 0 {
             return Ok((
-                Self {
+                PublicPacket {
                     packet_type: PacketType::VersionNegotiation,
                     dcid,
                     scid: Some(scid),
-                    token: &[],
+                    token: vec![],
                     header_len: decoder.offset(),
                     version: None,
                     data,
@@ -677,11 +678,11 @@ impl<'a> PublicPacket<'a> {
         // Check that this is a long header from a supported version.
         let Ok(version) = Version::try_from(version) else {
             return Ok((
-                Self {
+                PublicPacket {
                     packet_type: PacketType::OtherVersion,
                     dcid,
                     scid: Some(scid),
-                    token: &[],
+                    token: vec![],
                     header_len: decoder.offset(),
                     version: Some(version),
                     data,
@@ -696,11 +697,12 @@ impl<'a> PublicPacket<'a> {
         let packet_type = PacketType::from_byte((first >> 4) & 3, version);
 
         // The type-specific code includes a token.  This consumes the remainder of the packet.
-        let (token, header_len) = Self::decode_long(&mut decoder, packet_type, version)?;
+        let (token, header_len) = PublicPacket::decode_long(&mut decoder, packet_type, version)?;
+        let token = token.to_vec();
         let end = data.len() - decoder.remaining();
         let (data, remainder) = data.split_at_mut(end);
         Ok((
-            Self {
+            PublicPacket {
                 packet_type,
                 dcid,
                 scid: Some(scid),
@@ -751,22 +753,24 @@ impl<'a> PublicPacket<'a> {
     }
 
     #[must_use]
-    pub const fn dcid(&self) -> ConnectionIdRef<'a> {
-        self.dcid
+    pub fn dcid(&self) -> ConnectionIdRef {
+        self.dcid.as_cid_ref()
     }
 
     /// # Panics
     ///
     /// This will panic if called for a short header packet.
     #[must_use]
-    pub fn scid(&self) -> ConnectionIdRef<'a> {
+    pub fn scid(&self) -> ConnectionIdRef {
         self.scid
+            .as_ref()
             .expect("should only be called for long header packets")
+            .as_cid_ref()
     }
 
     #[must_use]
-    pub const fn token(&self) -> &'a [u8] {
-        self.token
+    pub fn token(&self) -> &[u8] {
+        &self.token
     }
 
     #[must_use]