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base repository: smoltcp-rs/smoltcp
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head repository: smoltcp-rs/smoltcp
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compare: 5c3fc4935eb0
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  • 2 commits
  • 2 files changed
  • 1 contributor

Commits on Jun 26, 2017

  1. Transmit actual UDP checksum of all-zeroes as all-ones instead.

    @whitequark
    whitequark committed Jun 26, 2017
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    e47e94e View commit details

  2. Discard packets with non-unicast source addresses at IP level. 

    This is required by RFC 1122 and helps avoid "broadcast storms".
    @whitequark
    whitequark committed Jun 26, 2017
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    5c3fc49 View commit details
Showing with 22 additions and 2 deletions.
  1. +6 −1 src/iface/ethernet.rs
  2. +16 −1 src/wire/udp.rs
7 changes: 6 additions & 1 deletion src/iface/ethernet.rs
View file
Original file line number Diff line number Diff line change
@@ -193,7 +193,12 @@ impl<'a, 'b, 'c, DeviceT: Device + 'a> Interface<'a, 'b, 'c, DeviceT> {
let ipv4_packet = Ipv4Packet::new_checked(eth_frame.payload())?;
let ipv4_repr = Ipv4Repr::parse(&ipv4_packet)?;

if ipv4_repr.src_addr.is_unicast() && eth_frame.src_addr().is_unicast() {
if ipv4_repr.src_addr.is_unicast() {
// Discard packets with non-unicast source addresses.
return Err(Error::Malformed)
}

if eth_frame.src_addr().is_unicast() {
// Fill the ARP cache from IP header of unicast frames.
self.arp_cache.fill(&IpAddress::Ipv4(ipv4_repr.src_addr),
&eth_frame.src_addr());
17 changes: 16 additions & 1 deletion src/wire/udp.rs
View file
Original file line number Diff line number Diff line change
@@ -173,7 +173,11 @@ impl<T: AsRef<[u8]> + AsMut<[u8]>> Packet<T> {
checksum::data(&data[..self.len() as usize])
])
};
self.set_checksum(checksum)
// UDP checksum value of 0 means no checksum; if the checksum really is zero,
// use all-ones, which indicates that the remote end must verify the checksum.
// Arithmetically, RFC 1071 checksums of all-zeroes and all-ones behave identically,
// so no action is necessary on the remote end.
self.set_checksum(if checksum == 0 { 0xffff } else { checksum })
}
}

@@ -317,6 +321,17 @@ mod test {
assert_eq!(packet.check_len(), Err(Error::Malformed));
}

#[test]
fn test_zero_checksum() {
let mut bytes = vec![0; 8];
let mut packet = Packet::new(&mut bytes);
packet.set_src_port(1);
packet.set_dst_port(31881);
packet.set_len(8);
packet.fill_checksum(&SRC_ADDR.into(), &DST_ADDR.into());
assert_eq!(packet.checksum(), 0xffff);
}

fn packet_repr() -> Repr<'static> {
Repr {
src_port: 48896,