Merge pull request #867 from thvdveld/tcp-dont-send-rst-to-unspecified

fix(tcp): don't send TCP RST with unsp. src addr

src/iface/interface/mod.rs

@@ -1337,8 +1337,12 @@ impl InterfaceInner {
             }
         }
 
-        if tcp_repr.control == TcpControl::Rst {
-            // Never reply to a TCP RST packet with another TCP RST packet.
+        if tcp_repr.control == TcpControl::Rst
+            || ip_repr.dst_addr().is_unspecified()
+            || ip_repr.src_addr().is_unspecified()
+        {
+            // Never reply to a TCP RST packet with another TCP RST packet. We also never want to
+            // send a TCP RST packet with unspecified addresses.
             None
         } else {
             // The packet wasn't handled by a socket, send a TCP RST packet.

src/iface/interface/tests/mod.rs

@@ -147,3 +147,99 @@ fn test_handle_udp_broadcast(
         Ok((&UDP_PAYLOAD[..], IpEndpoint::new(src_ip.into(), 67).into()))
     );
 }
+
+#[test]
+#[cfg(all(feature = "socket-tcp", feature = "proto-ipv6"))]
+pub fn tcp_not_accepted() {
+    use crate::iface::ip_packet::{IpPacket, IpPayload, Ipv6Packet};
+
+    let (mut iface, mut sockets, _) = setup(Medium::Ip);
+    let tcp = TcpRepr {
+        src_port: 4242,
+        dst_port: 4243,
+        control: TcpControl::Syn,
+        seq_number: TcpSeqNumber(-10001),
+        ack_number: None,
+        window_len: 256,
+        window_scale: None,
+        max_seg_size: None,
+        sack_permitted: false,
+        sack_ranges: [None, None, None],
+        payload: &[],
+    };
+
+    let mut tcp_bytes = vec![0u8; tcp.buffer_len()];
+
+    tcp.emit(
+        &mut TcpPacket::new_unchecked(&mut tcp_bytes),
+        &Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 2).into(),
+        &Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 1).into(),
+        &ChecksumCapabilities::default(),
+    );
+
+    assert_eq!(
+        iface.inner.process_tcp(
+            &mut sockets,
+            IpRepr::Ipv6(Ipv6Repr {
+                src_addr: Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 2),
+                dst_addr: Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 1),
+                next_header: IpProtocol::Tcp,
+                payload_len: tcp.buffer_len(),
+                hop_limit: 64,
+            }),
+            &tcp_bytes,
+        ),
+        Some(IpPacket::Ipv6(Ipv6Packet {
+            header: Ipv6Repr {
+                src_addr: Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 1),
+                dst_addr: Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 2),
+                next_header: IpProtocol::Tcp,
+                payload_len: tcp.buffer_len(),
+                hop_limit: 64,
+            },
+
+            #[cfg(feature = "proto-ipv6-hbh")]
+            hop_by_hop: None,
+            #[cfg(feature = "proto-ipv6-fragmentation")]
+            fragment: None,
+            #[cfg(feature = "proto-ipv6-routing")]
+            routing: None,
+
+            payload: IpPayload::Tcp(TcpRepr {
+                src_port: 4243,
+                dst_port: 4242,
+                control: TcpControl::Rst,
+                seq_number: TcpSeqNumber(0),
+                ack_number: Some(TcpSeqNumber(-10000)),
+                window_len: 0,
+                window_scale: None,
+                max_seg_size: None,
+                sack_permitted: false,
+                sack_ranges: [None, None, None],
+                payload: &[],
+            })
+        })),
+    );
+    // Unspecified destination address.
+    tcp.emit(
+        &mut TcpPacket::new_unchecked(&mut tcp_bytes),
+        &Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 2).into(),
+        &Ipv6Address::UNSPECIFIED.into(),
+        &ChecksumCapabilities::default(),
+    );
+
+    assert_eq!(
+        iface.inner.process_tcp(
+            &mut sockets,
+            IpRepr::Ipv6(Ipv6Repr {
+                src_addr: Ipv6Address::new(0xfe80, 0, 0, 0, 0, 0, 0, 2),
+                dst_addr: Ipv6Address::UNSPECIFIED,
+                next_header: IpProtocol::Tcp,
+                payload_len: tcp.buffer_len(),
+                hop_limit: 64,
+            }),
+            &tcp_bytes,
+        ),
+        None,
+    );
+}