Merge #547
547: Basic rand infrastructure. r=Dirbaio a=Dirbaio See [previous discussion](https://github.com/smoltcp-rs/smoltcp/pull/465#pullrequestreview-774487285). Opening a separate PR so it can be discussed separately. - Add `smoltcp::rand`. - On `std` targets, `OsRng` is used by default. - The user can supply a custom impl by enabling the `rand-custom-impl` Cargo feature and using the `rand_custom_impl!()` macro. - Specifying a custom impl is mandatory when `std` is not enabled. - Make TCP initial sequence numbers actually random. Co-authored-by: Dario Nieuwenhuis <dirbaio@dirbaio.net>master
commit
c0a46e2d14
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@ -48,7 +48,7 @@ jobs:
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include:
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# Test alloc feature which requires nightly.
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- rust: nightly
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features: alloc medium-ethernet proto-ipv4 proto-ipv6 socket-raw socket-udp socket-tcp socket-icmp
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features: alloc rand-custom-impl medium-ethernet proto-ipv4 proto-ipv6 socket-raw socket-udp socket-tcp socket-icmp
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steps:
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- uses: actions/checkout@v2
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- uses: actions-rs/toolchain@v1
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@ -73,8 +73,8 @@ jobs:
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features:
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# These feature sets cannot run tests, so we only check they build.
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- medium-ip medium-ethernet proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
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- defmt defmt-trace medium-ip medium-ethernet proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
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- rand-custom-impl medium-ip medium-ethernet proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
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- rand-custom-impl defmt defmt-trace medium-ip medium-ethernet proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
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steps:
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- uses: actions/checkout@v2
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@ -22,6 +22,7 @@ log = { version = "0.4.4", default-features = false, optional = true }
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libc = { version = "0.2.18", optional = true }
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bitflags = { version = "1.0", default-features = false }
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defmt = { version = "0.2.0", optional = true }
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rand_core = { version = "0.6.3", optional = true, default-features = false }
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[dev-dependencies]
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env_logger = "0.5"
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@ -30,9 +31,10 @@ rand = "0.3"
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url = "1.0"
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[features]
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std = ["managed/std"]
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std = ["managed/std", "rand_core/std"]
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alloc = ["managed/alloc"]
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verbose = []
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rand-custom-impl = []
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"medium-ethernet" = ["socket"]
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"medium-ip" = ["socket"]
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"phy-raw_socket" = ["std", "libc", "medium-ethernet"]
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@ -37,6 +37,14 @@ mod mock {
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self.0.get()
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}
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}
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struct Rand;
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smoltcp::rand_custom_impl!(Rand);
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impl smoltcp::Rand for Rand {
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fn rand_bytes(buf: &mut [u8]) {
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buf.fill(0x42);
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}
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}
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}
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#[cfg(feature = "std")]
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@ -126,6 +126,10 @@ use core::fmt;
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mod macros;
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mod parsers;
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mod rand;
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#[cfg(feature = "rand-custom-impl")]
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pub use crate::rand::Rand;
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pub mod iface;
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pub mod phy;
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#[cfg(feature = "socket")]
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@ -0,0 +1,67 @@
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#![allow(unsafe_code)]
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#![allow(unused)]
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#[cfg(not(any(test, feature = "std", feature = "rand-custom-impl")))]
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compile_error!("None of the Cargo features `std` or `rand-custom-impl` is enabled. smoltcp needs a `rand` implementation to work. If your target supports `std`, enable the `std` feature to use the OS's RNG. Otherwise, you must enable the `rand-custom-impl` Cargo feature, and supply your own custom implementation using the `smoltcp::rand_custom_impl!()` macro");
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pub fn rand_u32() -> u32 {
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let mut val = [0; 4];
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rand_bytes(&mut val);
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u32::from_ne_bytes(val)
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}
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/// Fill `buf` with random bytes.
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pub fn rand_bytes(buf: &mut [u8]) {
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extern "Rust" {
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fn _smoltcp_rand(buf: &mut [u8]);
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}
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unsafe { _smoltcp_rand(buf) }
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}
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/// Methods required for a custom rand implementation.
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///
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/// This trait is not intended to be used directly, just to supply a custom rand implementation to smoltcp.
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#[cfg(feature = "rand-custom-impl")]
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pub trait Rand {
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/// Fill `buf` with random bytes.
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fn rand_bytes(buf: &mut [u8]);
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}
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/// Set the custom rand implementation.
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///
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/// # Example
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///
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/// ```
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/// struct Rand;
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/// smoltcp::rand_custom_impl!(Rand);
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/// impl smoltcp::Rand for Rand {
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/// fn rand_bytes(buf: &mut [u8]) {
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/// // TODO
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/// }
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/// }
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///
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#[macro_export]
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#[cfg(feature = "rand-custom-impl")]
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macro_rules! rand_custom_impl {
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($t: ty) => {
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#[no_mangle]
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fn _smoltcp_rand(buf: &mut [u8]) {
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<$t as $crate::Rand>::rand_bytes(buf)
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}
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};
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}
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#[cfg(all(feature = "std", not(feature = "rand-custom-impl"), not(test)))]
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#[no_mangle]
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fn _smoltcp_rand(buf: &mut [u8]) {
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use rand_core::RngCore;
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rand_core::OsRng.fill_bytes(buf)
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}
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#[cfg(test)]
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#[no_mangle]
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fn _smoltcp_rand(buf: &mut [u8]) {
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panic!("Rand should not be used when testing");
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}
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@ -56,11 +56,6 @@ impl fmt::Display for State {
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}
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}
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/// Initial sequence number. This used to be 0, but some servers don't behave correctly
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/// with that, so we use a non-zero starting sequence number. TODO: randomize instead.
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/// https://github.com/smoltcp-rs/smoltcp/issues/489
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const INITIAL_SEQ_NO: TcpSeqNumber = TcpSeqNumber(42);
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// Conservative initial RTT estimate.
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const RTTE_INITIAL_RTT: u32 = 300;
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const RTTE_INITIAL_DEV: u32 = 100;
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@ -430,7 +425,7 @@ impl<'a> TcpSocket<'a> {
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listen_address: IpAddress::default(),
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local_endpoint: IpEndpoint::default(),
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remote_endpoint: IpEndpoint::default(),
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local_seq_no: INITIAL_SEQ_NO,
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local_seq_no: TcpSeqNumber::default(),
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remote_seq_no: TcpSeqNumber::default(),
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remote_last_seq: TcpSeqNumber::default(),
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remote_last_ack: None,
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self.listen_address = IpAddress::default();
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self.local_endpoint = IpEndpoint::default();
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self.remote_endpoint = IpEndpoint::default();
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self.local_seq_no = INITIAL_SEQ_NO;
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self.local_seq_no = TcpSeqNumber::default();
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self.remote_seq_no = TcpSeqNumber::default();
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self.remote_last_seq = TcpSeqNumber::default();
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self.remote_last_ack = None;
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..local_endpoint
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};
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// Carry over the local sequence number.
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let local_seq_no = self.local_seq_no;
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self.reset();
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self.local_endpoint = local_endpoint;
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self.remote_endpoint = remote_endpoint;
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self.local_seq_no = local_seq_no;
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self.remote_last_seq = local_seq_no;
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self.set_state(State::SynSent);
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let seq = Self::random_seq_no();
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self.local_seq_no = seq;
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self.remote_last_seq = seq;
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Ok(())
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}
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fn random_seq_no() -> TcpSeqNumber {
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#[cfg(test)]
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return TcpSeqNumber(10000);
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#[cfg(not(test))]
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return TcpSeqNumber(crate::rand::rand_u32() as i32);
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}
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/// Close the transmit half of the full-duplex connection.
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///
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/// Note that there is no corresponding function for the receive half of the full-duplex
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self.local_endpoint = IpEndpoint::new(ip_repr.dst_addr(), repr.dst_port);
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self.remote_endpoint = IpEndpoint::new(ip_repr.src_addr(), repr.src_port);
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// FIXME: use something more secure here
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self.local_seq_no = TcpSeqNumber(!repr.seq_number.0);
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self.local_seq_no = Self::random_seq_no();
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self.remote_seq_no = repr.seq_number + 1;
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self.remote_last_seq = self.local_seq_no;
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self.remote_has_sack = repr.sack_permitted;
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