smoltcp-rs · Sep 8, 2017 · Sep 8, 2017 · Sep 8, 2017 · Sep 8, 2017
Showing with 180 additions and 39 deletions.

+13 −11 src/iface/ethernet.rs

+0 −5 src/lib.rs

+26 −4 src/socket/raw.rs

+99 −15 src/socket/tcp.rs

+42 −4 src/socket/udp.rs
diff --git a/src/iface/ethernet.rs b/src/iface/ethernet.rs
@@ -289,13 +289,15 @@ impl<'a, 'b, 'c, DeviceT: Device + 'a> Interface<'a, 'b, 'c, DeviceT> {
         let mut handled_by_raw_socket = false;
         for raw_socket in sockets.iter_mut().filter_map(
                 <Socket as AsSocket<RawSocket>>::try_as_socket) {
+            if !raw_socket.accepts(&ip_repr) { continue }
+
             match raw_socket.process(&ip_repr, ip_payload) {
                 // The packet is valid and handled by socket.
                 Ok(()) => handled_by_raw_socket = true,
-                // The packet isn't addressed to the socket, or cannot be accepted by it.
-                Err(Error::Rejected) | Err(Error::Exhausted) => (),
-                // Raw sockets either accept or reject packets, not parse them.
-                _ => unreachable!(),
+                // The socket buffer is full.
+                Err(Error::Exhausted) => (),
+                // Raw sockets don't validate the packets in any way.
+                Err(_) => unreachable!(),
             }
         }
 
@@ -369,12 +371,12 @@ impl<'a, 'b, 'c, DeviceT: Device + 'a> Interface<'a, 'b, 'c, DeviceT> {
 
         for udp_socket in sockets.iter_mut().filter_map(
                 <Socket as AsSocket<UdpSocket>>::try_as_socket) {
+            if !udp_socket.accepts(&ip_repr, &udp_repr) { continue }
+
             match udp_socket.process(&ip_repr, &udp_repr) {
                 // The packet is valid and handled by socket.
                 Ok(()) => return Ok(Packet::None),
-                // The packet isn't addressed to the socket.
-                Err(Error::Rejected) => continue,
-                // The packet is malformed, or addressed to the socket but cannot be accepted.
+                // The packet is malformed, or the socket buffer is full.
                 Err(e) => return Err(e)
             }
         }
@@ -410,13 +412,13 @@ impl<'a, 'b, 'c, DeviceT: Device + 'a> Interface<'a, 'b, 'c, DeviceT> {
 
         for tcp_socket in sockets.iter_mut().filter_map(
                 <Socket as AsSocket<TcpSocket>>::try_as_socket) {
+            if !tcp_socket.accepts(&ip_repr, &tcp_repr) { continue }
+
             match tcp_socket.process(timestamp, &ip_repr, &tcp_repr) {
                 // The packet is valid and handled by socket.
                 Ok(reply) => return Ok(reply.map_or(Packet::None, Packet::Tcp)),
-                // The packet isn't addressed to the socket.
-                // Send RST only if no other socket accepts the packet.
-                Err(Error::Rejected) => continue,
-                // The packet is malformed, or addressed to the socket but cannot be accepted.
+                // The packet is malformed, or doesn't match the socket state,
+                // or the socket buffer is full.
                 Err(e) => return Err(e)
             }
         }

diff --git a/src/lib.rs b/src/lib.rs
@@ -126,10 +126,6 @@ pub enum Error {
     /// E.g. a TCP packet addressed to a socket that doesn't exist.
     Dropped,
 
-    // Implementation detail.
-    #[doc(hidden)]
-    Rejected,
-
     #[doc(hidden)]
     __Nonexhaustive
 }
@@ -149,7 +145,6 @@ impl fmt::Display for Error {
             &Error::Fragmented    => write!(f, "fragmented packet"),
             &Error::Malformed     => write!(f, "malformed packet"),
             &Error::Dropped       => write!(f, "dropped by socket"),
-            &Error::Rejected      => write!(f, "rejected by socket"),
             &Error::__Nonexhaustive => unreachable!()
         }
     }

diff --git a/src/socket/raw.rs b/src/socket/raw.rs
@@ -166,9 +166,15 @@ impl<'a, 'b> RawSocket<'a, 'b> {
         Ok(length)
     }
 
+    pub(crate) fn accepts(&self, ip_repr: &IpRepr) -> bool {
+        if ip_repr.version() != self.ip_version { return false }
+        if ip_repr.protocol() != self.ip_protocol { return false }
+
+        true
+    }
+
     pub(crate) fn process(&mut self, ip_repr: &IpRepr, payload: &[u8]) -> Result<()> {
-        if ip_repr.version() != self.ip_version { return Err(Error::Rejected) }
-        if ip_repr.protocol() != self.ip_protocol { return Err(Error::Rejected) }
+        debug_assert!(self.accepts(ip_repr));
 
         let header_len = ip_repr.buffer_len();
         let total_len = header_len + payload.len();
@@ -246,17 +252,18 @@ mod test {
     fn socket(rx_buffer: SocketBuffer<'static, 'static>,
               tx_buffer: SocketBuffer<'static, 'static>)
             -> RawSocket<'static, 'static> {
-        match RawSocket::new(IpVersion::Ipv4, IpProtocol::Unknown(63),
+        match RawSocket::new(IpVersion::Ipv4, IpProtocol::Unknown(IP_PROTO),
                              rx_buffer, tx_buffer) {
             Socket::Raw(socket) => socket,
             _ => unreachable!()
         }
     }
 
+    const IP_PROTO: u8 = 63;
     const HEADER_REPR: IpRepr = IpRepr::Ipv4(Ipv4Repr {
         src_addr: Ipv4Address([10, 0, 0, 1]),
         dst_addr: Ipv4Address([10, 0, 0, 2]),
-        protocol: IpProtocol::Unknown(63),
+        protocol: IpProtocol::Unknown(IP_PROTO),
         payload_len: 4
     });
     const PACKET_BYTES: [u8; 24] = [
@@ -332,10 +339,12 @@ mod test {
         Ipv4Packet::new(&mut cksumd_packet).fill_checksum();
 
         assert_eq!(socket.recv(), Err(Error::Exhausted));
+        assert!(socket.accepts(&HEADER_REPR));
         assert_eq!(socket.process(&HEADER_REPR, &PACKET_PAYLOAD),
                    Ok(()));
         assert!(socket.can_recv());
 
+        assert!(socket.accepts(&HEADER_REPR));
         assert_eq!(socket.process(&HEADER_REPR, &PACKET_PAYLOAD),
                    Err(Error::Exhausted));
         assert_eq!(socket.recv(), Ok(&cksumd_packet[..]));
@@ -346,6 +355,7 @@ mod test {
     fn test_recv_truncated_slice() {
         let mut socket = socket(buffer(1), buffer(0));
 
+        assert!(socket.accepts(&HEADER_REPR));
         assert_eq!(socket.process(&HEADER_REPR, &PACKET_PAYLOAD),
                    Ok(()));
 
@@ -361,7 +371,19 @@ mod test {
         let mut buffer = vec![0; 128];
         buffer[..PACKET_BYTES.len()].copy_from_slice(&PACKET_BYTES[..]);
 
+        assert!(socket.accepts(&HEADER_REPR));
         assert_eq!(socket.process(&HEADER_REPR, &buffer),
                    Err(Error::Truncated));
     }
+
+    #[test]
+    fn test_doesnt_accept_wrong_proto() {
+        let socket = match RawSocket::new(IpVersion::Ipv4,
+                                          IpProtocol::Unknown(IP_PROTO+1),
+                                          buffer(1), buffer(1)) {
+            Socket::Raw(socket) => socket,
+            _ => unreachable!()
+        };
+        assert!(!socket.accepts(&HEADER_REPR));
+    }
 }
diff --git a/src/socket/tcp.rs b/src/socket/tcp.rs
@@ -666,25 +666,31 @@ impl<'a> TcpSocket<'a> {
         (ip_reply_repr, reply_repr)
     }
 
-    pub(crate) fn process(&mut self, timestamp: u64, ip_repr: &IpRepr, repr: &TcpRepr) ->
-                         Result<Option<(IpRepr, TcpRepr<'static>)>> {
-        if self.state == State::Closed { return Err(Error::Rejected) }
+    pub(crate) fn accepts(&self, ip_repr: &IpRepr, repr: &TcpRepr) -> bool {
+        if self.state == State::Closed { return false }
 
         // If we're still listening for SYNs and the packet has an ACK, it cannot
         // be destined to this socket, but another one may well listen on the same
         // local endpoint.
-        if self.state == State::Listen && repr.ack_number.is_some() { return Err(Error::Rejected) }
+        if self.state == State::Listen && repr.ack_number.is_some() { return false }
 
         // Reject packets with a wrong destination.
-        if self.local_endpoint.port != repr.dst_port { return Err(Error::Rejected) }
+        if self.local_endpoint.port != repr.dst_port { return false }
         if !self.local_endpoint.addr.is_unspecified() &&
-           self.local_endpoint.addr != ip_repr.dst_addr() { return Err(Error::Rejected) }
+            self.local_endpoint.addr != ip_repr.dst_addr() { return false }
 
         // Reject packets from a source to which we aren't connected.
         if self.remote_endpoint.port != 0 &&
-           self.remote_endpoint.port != repr.src_port { return Err(Error::Rejected) }
+            self.remote_endpoint.port != repr.src_port { return false }
         if !self.remote_endpoint.addr.is_unspecified() &&
-           self.remote_endpoint.addr != ip_repr.src_addr() { return Err(Error::Rejected) }
+            self.remote_endpoint.addr != ip_repr.src_addr() { return false }
+
+        true
+    }
+
+    pub(crate) fn process(&mut self, timestamp: u64, ip_repr: &IpRepr, repr: &TcpRepr) ->
+                         Result<Option<(IpRepr, TcpRepr<'static>)>> {
+        debug_assert!(self.accepts(ip_repr, repr));
 
         // Consider how much the sequence number space differs from the transmit buffer space.
         let (sent_syn, sent_fin) = match self.state {
@@ -1241,20 +1247,29 @@ mod test {
 
     const LOCAL_IP:     IpAddress    = IpAddress::Ipv4(Ipv4Address([10, 0, 0, 1]));
     const REMOTE_IP:    IpAddress    = IpAddress::Ipv4(Ipv4Address([10, 0, 0, 2]));
+    const OTHER_IP:     IpAddress    = IpAddress::Ipv4(Ipv4Address([10, 0, 0, 3]));
     const LOCAL_PORT:   u16          = 80;
     const REMOTE_PORT:  u16          = 49500;
     const LOCAL_END:    IpEndpoint   = IpEndpoint { addr: LOCAL_IP,  port: LOCAL_PORT  };
     const REMOTE_END:   IpEndpoint   = IpEndpoint { addr: REMOTE_IP, port: REMOTE_PORT };
     const LOCAL_SEQ:    TcpSeqNumber = TcpSeqNumber(10000);
     const REMOTE_SEQ:   TcpSeqNumber = TcpSeqNumber(-10000);
 
+    const SEND_IP_TEMPL: IpRepr = IpRepr::Unspecified {
+        src_addr: LOCAL_IP, dst_addr: REMOTE_IP,
+        protocol: IpProtocol::Tcp, payload_len: 20
+    };
     const SEND_TEMPL: TcpRepr<'static> = TcpRepr {
         src_port: REMOTE_PORT, dst_port: LOCAL_PORT,
         control: TcpControl::None,
         seq_number: TcpSeqNumber(0), ack_number: Some(TcpSeqNumber(0)),
         window_len: 256, max_seg_size: None,
         payload: &[]
     };
+    const RECV_IP_TEMPL: IpRepr = IpRepr::Unspecified {
+        src_addr: REMOTE_IP, dst_addr: LOCAL_IP,
+        protocol: IpProtocol::Tcp, payload_len: 20
+    };
     const RECV_TEMPL:  TcpRepr<'static> = TcpRepr {
         src_port: LOCAL_PORT, dst_port: REMOTE_PORT,
         control: TcpControl::None,
@@ -1265,13 +1280,15 @@ mod test {
 
     fn send(socket: &mut TcpSocket, timestamp: u64, repr: &TcpRepr) ->
            Result<Option<TcpRepr<'static>>> {
-        trace!("send: {}", repr);
         let ip_repr = IpRepr::Unspecified {
             src_addr:    REMOTE_IP,
             dst_addr:    LOCAL_IP,
             protocol:    IpProtocol::Tcp,
             payload_len: repr.buffer_len()
         };
+        trace!("send: {}", repr);
+
+        assert!(socket.accepts(&ip_repr, repr));
         match socket.process(timestamp, &ip_repr, repr) {
             Ok(Some((_ip_repr, repr))) => {
                 trace!("recv: {}", repr);
@@ -1395,10 +1412,11 @@ mod test {
         let mut s = socket();
         assert_eq!(s.state, State::Closed);
 
-        send!(s, TcpRepr {
+        let tcp_repr = TcpRepr {
             control: TcpControl::Syn,
             ..SEND_TEMPL
-        }, Err(Error::Rejected));
+        };
+        assert!(!s.accepts(&SEND_IP_TEMPL, &tcp_repr));
     }
 
     #[test]
@@ -1407,10 +1425,11 @@ mod test {
         s.listen(LOCAL_END).unwrap();
         s.close();
 
-        send!(s, TcpRepr {
+        let tcp_repr = TcpRepr {
             control: TcpControl::Syn,
             ..SEND_TEMPL
-        }, Err(Error::Rejected));
+        };
+        assert!(!s.accepts(&SEND_IP_TEMPL, &tcp_repr));
     }
 
     #[test]
@@ -1465,12 +1484,15 @@ mod test {
     #[test]
     fn test_listen_syn_reject_ack() {
         let mut s = socket_listen();
-        send!(s, TcpRepr {
+
+        let tcp_repr = TcpRepr {
             control: TcpControl::Syn,
             seq_number: REMOTE_SEQ,
             ack_number: Some(LOCAL_SEQ),
             ..SEND_TEMPL
-        }, Err(Error::Rejected));
+        };
+        assert!(!s.accepts(&SEND_IP_TEMPL, &tcp_repr));
+
         assert_eq!(s.state, State::Listen);
     }
 
@@ -2930,4 +2952,66 @@ mod test {
             ..RECV_TEMPL
         }]);
     }
+
+    // =========================================================================================//
+    // Tests for packet filtering
+    // =========================================================================================//
+
+    #[test]
+    fn test_doesnt_accept_wrong_port() {
+        let mut s = socket_established();
+        s.rx_buffer = SocketBuffer::new(vec![0; 6]);
+
+        let tcp_repr = TcpRepr {
+            seq_number: REMOTE_SEQ + 1,
+            ack_number: Some(LOCAL_SEQ + 1),
+            dst_port:   LOCAL_PORT + 1,
+            ..SEND_TEMPL
+        };
+        assert!(!s.accepts(&SEND_IP_TEMPL, &tcp_repr));
+
+        let tcp_repr = TcpRepr {
+            seq_number: REMOTE_SEQ + 1,
+            ack_number: Some(LOCAL_SEQ + 1),
+            src_port:   REMOTE_PORT + 1,
+            ..SEND_TEMPL
+        };
+        assert!(!s.accepts(&SEND_IP_TEMPL, &tcp_repr));
+    }
+
+    #[test]
+    fn test_doesnt_accept_wrong_ip() {
+        let s = socket_established();
+
+        let tcp_repr = TcpRepr {
+            seq_number: REMOTE_SEQ + 1,
+            ack_number: Some(LOCAL_SEQ + 1),
+            payload:    &b"abcdef"[..],
+            ..SEND_TEMPL
+        };
+
+        let ip_repr = IpRepr::Unspecified {
+            src_addr:    REMOTE_IP,
+            dst_addr:    LOCAL_IP,
+            protocol:    IpProtocol::Tcp,
+            payload_len: tcp_repr.buffer_len()
+        };
+        assert!(s.accepts(&ip_repr, &tcp_repr));
+
+        let ip_repr_wrong_src = IpRepr::Unspecified {
+            src_addr:    OTHER_IP,
+            dst_addr:    LOCAL_IP,
+            protocol:    IpProtocol::Tcp,
+            payload_len: tcp_repr.buffer_len()
+        };
+        assert!(!s.accepts(&ip_repr_wrong_src, &tcp_repr));
+
+        let ip_repr_wrong_dst = IpRepr::Unspecified {
+            src_addr:    REMOTE_IP,
+            dst_addr:    OTHER_IP,
+            protocol:    IpProtocol::Tcp,
+            payload_len: tcp_repr.buffer_len()
+        };
+        assert!(!s.accepts(&ip_repr_wrong_dst, &tcp_repr));
+    }
 }