shadow_rs/host/descriptor/socket/inet/udp.rs
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use std::collections::LinkedList;
use std::io::{Read, Write};
use std::net::{Ipv4Addr, SocketAddrV4};
use std::sync::Arc;
use atomic_refcell::AtomicRefCell;
use bytes::{Bytes, BytesMut};
use linux_api::errno::Errno;
use linux_api::ioctls::IoctlRequest;
use linux_api::socket::Shutdown;
use nix::sys::socket::{MsgFlags, SockaddrIn};
use shadow_shim_helper_rs::emulated_time::EmulatedTime;
use shadow_shim_helper_rs::syscall_types::ForeignPtr;
use crate::core::worker::Worker;
use crate::cshadow as c;
use crate::host::descriptor::listener::{StateEventSource, StateListenHandle, StateListenerFilter};
use crate::host::descriptor::socket::inet::{self, InetSocket};
use crate::host::descriptor::socket::{RecvmsgArgs, RecvmsgReturn, SendmsgArgs, ShutdownFlags};
use crate::host::descriptor::{
File, FileMode, FileSignals, FileState, FileStatus, OpenFile, Socket, SyscallResult,
};
use crate::host::memory_manager::MemoryManager;
use crate::host::network::interface::FifoPacketPriority;
use crate::host::network::namespace::{AssociationHandle, NetworkNamespace};
use crate::host::syscall::io::{write_partial, IoVec, IoVecReader, IoVecWriter};
use crate::host::syscall::types::SyscallError;
use crate::network::packet::{PacketRc, PacketStatus};
use crate::utility::callback_queue::CallbackQueue;
use crate::utility::sockaddr::SockaddrStorage;
use crate::utility::{HostTreePointer, ObjectCounter};
/// Maximum size of a datagram we are allowed to send out over the network.
// 65,535 (2^16 - 1) - 20 (ip header) - 8 (udp header)
const CONFIG_DATAGRAM_MAX_SIZE: usize = 65507;
pub struct UdpSocket {
event_source: StateEventSource,
status: FileStatus,
state: FileState,
shutdown_status: ShutdownFlags,
send_buffer: MessageBuffer<MessageSendHeader>,
recv_buffer: MessageBuffer<MessageRecvHeader>,
peer_addr: Option<SocketAddrV4>,
bound_addr: Option<SocketAddrV4>,
association: Option<AssociationHandle>,
/// The receive time of the last packet returned to the managed process during a call to
/// `recvmsg()`. Used for `SIOCGSTAMP`.
recv_time_of_last_read_packet: Option<EmulatedTime>,
// should only be used by `OpenFile` to make sure there is only ever one `OpenFile` instance for
// this file
has_open_file: bool,
_counter: ObjectCounter,
}
impl UdpSocket {
pub fn new(
status: FileStatus,
send_buf_size: usize,
recv_buf_size: usize,
) -> Arc<AtomicRefCell<Self>> {
let mut socket = Self {
event_source: StateEventSource::new(),
status,
state: FileState::ACTIVE,
shutdown_status: ShutdownFlags::empty(),
send_buffer: MessageBuffer::new(send_buf_size),
recv_buffer: MessageBuffer::new(recv_buf_size),
peer_addr: None,
bound_addr: None,
association: None,
recv_time_of_last_read_packet: None,
has_open_file: false,
_counter: ObjectCounter::new("UdpSocket"),
};
CallbackQueue::queue_and_run_with_legacy(|cb_queue| {
socket.refresh_readable_writable(FileSignals::empty(), cb_queue)
});
Arc::new(AtomicRefCell::new(socket))
}
pub fn status(&self) -> FileStatus {
self.status
}
pub fn set_status(&mut self, status: FileStatus) {
self.status = status;
}
pub fn mode(&self) -> FileMode {
FileMode::READ | FileMode::WRITE
}
pub fn has_open_file(&self) -> bool {
self.has_open_file
}
pub fn supports_sa_restart(&self) -> bool {
true
}
pub fn set_has_open_file(&mut self, val: bool) {
self.has_open_file = val;
}
pub fn push_in_packet(
&mut self,
mut packet: PacketRc,
cb_queue: &mut CallbackQueue,
recv_time: EmulatedTime,
) {
packet.add_status(PacketStatus::RcvSocketProcessed);
if let Some(peer_addr) = self.peer_addr {
if peer_addr != packet.src_address() {
// connect(2): "If the socket sockfd is of type SOCK_DGRAM, then addr is the address
// to which datagrams are sent by default, and the only address from which datagrams
// are received."
// we have a peer, but received a packet from a different source address than that
// peer
packet.add_status(PacketStatus::RcvSocketDropped);
// TODO: There's a race condition where we check the packet's address only when
// receiving the packet from the network interface, but the user could call
// `connect()` to set a peer after we've already received and buffered this packet.
// My guess is that this race condition exists in Linux as well, but ideally we
// should add a test, and do another check when `recvmsg()` is called if we really
// need to.
return;
}
};
// TODO: also check the dst address to make sure we are the intended socket?
// don't bother copying the bytes if we know the push will fail
if !self.recv_buffer.has_space() {
packet.add_status(PacketStatus::RcvSocketDropped);
return;
}
// in the future, the packet could contain the `Bytes` object itself and we could simply
// transfer the `Bytes` directly from the packet to the buffer without copying the bytes
let mut message = BytesMut::zeroed(packet.payload_size());
let num_bytes_copied = packet.get_payload(&mut message);
assert_eq!(num_bytes_copied, packet.payload_size());
let header = MessageRecvHeader {
src: packet.src_address(),
dst: packet.dst_address(),
recv_time,
};
// push the message to the receive buffer (shouldn't fail since we checked for available
// space above)
self.recv_buffer
.push_message(message.freeze(), header)
.unwrap();
log::trace!("Added a packet to the UDP socket's recv buffer");
packet.add_status(PacketStatus::RcvSocketBuffered);
self.refresh_readable_writable(FileSignals::READ_BUFFER_GREW, cb_queue);
}
pub fn pull_out_packet(&mut self, cb_queue: &mut CallbackQueue) -> Option<PacketRc> {
// pop the message from the send buffer
let Some((message, header)) = self.send_buffer.pop_message() else {
log::debug!(
"Attempted to remove a message from the UDP socket's send buffer, but none available"
);
return None;
};
log::trace!("Removed a message from the UDP socket's send buffer");
let mut packet = PacketRc::new();
let priority = header.packet_priority;
// in the future, the packet could contain the `Bytes` object itself and we could simply
// transfer the `Bytes` directly from the buffer to the packet without copying the bytes
packet.set_udp(header.src, header.dst);
packet.set_payload(&message, priority);
packet.add_status(PacketStatus::SndCreated);
self.refresh_readable_writable(FileSignals::empty(), cb_queue);
Some(packet)
}
pub fn peek_next_packet_priority(&self) -> Option<FifoPacketPriority> {
self.send_buffer.buffer.front().map(|x| x.1.packet_priority)
}
pub fn has_data_to_send(&self) -> bool {
!self.send_buffer.is_empty()
}
pub fn getsockname(&self) -> Result<Option<SockaddrIn>, Errno> {
let mut addr = self
.bound_addr
.unwrap_or(SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, 0));
// if we are bound to INADDR_ANY, we should instead return the IP used to communicate with
// the connected peer (if we have one)
if *addr.ip() == Ipv4Addr::UNSPECIFIED {
if let Some(peer_addr) = self.peer_addr {
addr.set_ip(*peer_addr.ip());
}
}
Ok(Some(addr.into()))
}
pub fn getpeername(&self) -> Result<Option<SockaddrIn>, Errno> {
Ok(Some(self.peer_addr.ok_or(Errno::ENOTCONN)?.into()))
}
pub fn address_family(&self) -> linux_api::socket::AddressFamily {
linux_api::socket::AddressFamily::AF_INET
}
pub fn close(&mut self, cb_queue: &mut CallbackQueue) -> Result<(), SyscallError> {
// drop the existing association handle to disassociate the socket
self.association = None;
self.update_state(
/* mask= */ FileState::all(),
FileState::CLOSED,
FileSignals::empty(),
cb_queue,
);
Ok(())
}
pub fn bind(
socket: &Arc<AtomicRefCell<Self>>,
addr: Option<&SockaddrStorage>,
net_ns: &NetworkNamespace,
rng: impl rand::Rng,
) -> Result<(), SyscallError> {
// if the address pointer was NULL
let Some(addr) = addr else {
return Err(Errno::EFAULT.into());
};
// if not an inet socket address
let Some(addr) = addr.as_inet() else {
return Err(Errno::EINVAL.into());
};
let addr: SocketAddrV4 = (*addr).into();
{
let socket = socket.borrow();
// if the socket is already bound
if socket.bound_addr.is_some() {
return Err(Errno::EINVAL.into());
}
// Since we're not bound, we must not have a peer. We may have a peer in the future if
// `connect()` is called on this socket.
assert!(socket.peer_addr.is_none());
// must not have been associated with the network interface
assert!(socket.association.is_none());
}
// this will allow us to receive packets from any peer
let unspecified_addr = SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, 0);
// associate the socket
let (addr, handle) = inet::associate_socket(
InetSocket::Udp(Arc::clone(socket)),
addr,
unspecified_addr,
/* check_generic_peer= */ true,
net_ns,
rng,
)?;
// update the socket's local address
{
let mut socket = socket.borrow_mut();
socket.bound_addr = Some(addr);
socket.association = Some(handle);
}
Ok(())
}
pub fn readv(
&mut self,
_iovs: &[IoVec],
_offset: Option<libc::off_t>,
_flags: libc::c_int,
_mem: &mut MemoryManager,
_cb_queue: &mut CallbackQueue,
) -> Result<libc::ssize_t, SyscallError> {
// we could call UdpSocket::recvmsg() here, but for now we expect that there are no code
// paths that would call UdpSocket::readv() since the readv() syscall handler should have
// called UdpSocket::recvmsg() instead
panic!("Called UdpSocket::readv() on a UDP socket");
}
pub fn writev(
&mut self,
_iovs: &[IoVec],
_offset: Option<libc::off_t>,
_flags: libc::c_int,
_mem: &mut MemoryManager,
_cb_queue: &mut CallbackQueue,
) -> Result<libc::ssize_t, SyscallError> {
// we could call UdpSocket::sendmsg() here, but for now we expect that there are no code
// paths that would call UdpSocket::writev() since the writev() syscall handler should have
// called UdpSocket::sendmsg() instead
panic!("Called UdpSocket::writev() on a UDP socket");
}
pub fn sendmsg(
socket: &Arc<AtomicRefCell<Self>>,
args: SendmsgArgs,
mem: &mut MemoryManager,
net_ns: &NetworkNamespace,
rng: impl rand::Rng,
cb_queue: &mut CallbackQueue,
) -> Result<libc::ssize_t, SyscallError> {
let mut socket_ref = socket.borrow_mut();
// if the file's writing has been shut down, return EPIPE
if socket_ref.shutdown_status.contains(ShutdownFlags::WRITE) {
return Err(linux_api::errno::Errno::EPIPE.into());
}
let Some(mut flags) = MsgFlags::from_bits(args.flags) else {
log::debug!("Unrecognized send flags: {:#b}", args.flags);
return Err(Errno::EINVAL.into());
};
let dst_addr = match args.addr {
Some(addr) => match addr.as_inet() {
// an inet socket address
Some(x) => (*x).into(),
// not an inet socket address
None => return Err(Errno::EAFNOSUPPORT.into()),
},
// no destination address provided
None => match socket_ref.peer_addr {
Some(x) => x,
None => return Err(Errno::EDESTADDRREQ.into()),
},
};
if socket_ref.status().contains(FileStatus::NONBLOCK) {
flags.insert(MsgFlags::MSG_DONTWAIT);
}
let len: libc::size_t = args.iovs.iter().map(|x| x.len).sum();
// TODO: should use IP fragmentation to make sure packets fit within the MTU
if len > CONFIG_DATAGRAM_MAX_SIZE {
return Err(linux_api::errno::Errno::EMSGSIZE.into());
}
// make sure that we're bound
if socket_ref.bound_addr.is_some() {
// we must have an association since we're bound
assert!(socket_ref.association.is_some());
} else {
// we can't be unbound but have a peer
assert!(socket_ref.peer_addr.is_none());
assert!(socket_ref.association.is_none());
// implicit bind (use default interface unless the remote peer is on loopback)
// TODO: is this correct? or should we bind to UNSPECIFIED?
let local_addr = if dst_addr.ip() == &std::net::Ipv4Addr::LOCALHOST {
SocketAddrV4::new(Ipv4Addr::LOCALHOST, 0)
} else {
SocketAddrV4::new(net_ns.default_ip, 0)
};
// this will allow us to receive packets from any peer
let unspecified_addr = SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, 0);
let (local_addr, handle) = super::associate_socket(
InetSocket::Udp(Arc::clone(socket)),
local_addr,
unspecified_addr,
/* check_generic_peer= */ true,
net_ns,
rng,
)?;
socket_ref.bound_addr = Some(local_addr);
socket_ref.association = Some(handle);
}
// run in a closure so that an early return doesn't skip checking if we should block
let result = (|| {
// don't bother copying the bytes if we know the push will fail
if !socket_ref.send_buffer.has_space() {
return Err(Errno::EWOULDBLOCK);
}
// write the iovs to an empty message
let mut reader = IoVecReader::new(args.iovs, mem);
let mut message = BytesMut::zeroed(len);
reader
.read_exact(&mut message[..])
.map_err(|e| Errno::try_from(e).unwrap())?;
// get the priority that we'll assign to the eventual packet
let packet_priority =
Worker::with_active_host(|host| host.get_next_packet_priority()).unwrap();
let src_addr = socket_ref.bound_addr.unwrap();
let src_addr = if src_addr.ip().is_unspecified() {
// depending on the destination address, choose either localhost or the public IP
// address
if dst_addr.ip() == &std::net::Ipv4Addr::LOCALHOST {
SocketAddrV4::new(Ipv4Addr::LOCALHOST, src_addr.port())
} else {
SocketAddrV4::new(net_ns.default_ip, src_addr.port())
}
} else {
src_addr
};
let header = MessageSendHeader {
src: src_addr,
dst: dst_addr,
packet_priority,
};
// push the message to the send buffer (shouldn't fail since we checked for available
// space above)
socket_ref
.send_buffer
.push_message(message.freeze(), header)
.unwrap();
// notify the host that this socket has packets to send
let socket = Arc::clone(socket);
let interface_ip = *socket_ref.bound_addr.unwrap().ip();
cb_queue.add(move |_cb_queue| {
Worker::with_active_host(|host| {
let socket = InetSocket::Udp(socket);
host.notify_socket_has_packets(interface_ip, &socket);
})
.unwrap();
});
Ok(len)
})();
socket_ref.refresh_readable_writable(FileSignals::empty(), cb_queue);
// if the syscall would block and we don't have the MSG_DONTWAIT flag
if result == Err(Errno::EWOULDBLOCK) && !flags.contains(MsgFlags::MSG_DONTWAIT) {
return Err(SyscallError::new_blocked_on_file(
File::Socket(Socket::Inet(InetSocket::Udp(socket.clone()))),
FileState::WRITABLE,
socket_ref.supports_sa_restart(),
));
}
Ok(result?.try_into().unwrap())
}
pub fn recvmsg(
socket: &Arc<AtomicRefCell<Self>>,
args: RecvmsgArgs,
mem: &mut MemoryManager,
cb_queue: &mut CallbackQueue,
) -> Result<RecvmsgReturn, SyscallError> {
let socket_ref = &mut *socket.borrow_mut();
let Some(mut flags) = MsgFlags::from_bits(args.flags) else {
log::debug!("Unrecognized recv flags: {:#b}", args.flags);
return Err(Errno::EINVAL.into());
};
if socket_ref.status().contains(FileStatus::NONBLOCK) {
flags.insert(MsgFlags::MSG_DONTWAIT);
}
let len: libc::size_t = args.iovs.iter().map(|x| x.len).sum();
// run in a closure so that an early return doesn't skip checking if we should block
let result = (|| {
// a temporary location to store the message and header if we popped them
let message_storage;
let header_storage;
let (message, header) = if !flags.contains(MsgFlags::MSG_PEEK) {
// pop the message from the receive buffer
(message_storage, header_storage) = socket_ref
.recv_buffer
.pop_message()
.ok_or(Errno::EWOULDBLOCK)?;
(&message_storage, &header_storage)
} else {
// peek the message from the receive buffer
let (message, header) = socket_ref
.recv_buffer
.peek_message()
.ok_or(Errno::EWOULDBLOCK)?;
(message, header)
};
// truncate the payload if the payload is larger than the user-provided buffers
let truncated_message = &message[..std::cmp::min(len, message.len())];
// write the truncated message to the iovs
let mut writer = IoVecWriter::new(args.iovs, mem);
writer
.write_all(truncated_message)
.map_err(|e| Errno::try_from(e).unwrap())?;
let return_val = if flags.contains(MsgFlags::MSG_TRUNC) {
message.len()
} else {
// the number of bytes written
truncated_message.len()
};
let mut return_flags = MsgFlags::empty();
return_flags.set(MsgFlags::MSG_TRUNC, truncated_message.len() < message.len());
// update the cache of the last recv time
socket_ref.recv_time_of_last_read_packet = Some(header.recv_time);
Ok(RecvmsgReturn {
return_val: return_val.try_into().unwrap(),
addr: Some(header.src.into()),
msg_flags: return_flags.bits(),
control_len: 0,
})
})();
socket_ref.refresh_readable_writable(FileSignals::empty(), cb_queue);
// if the syscall would block and we don't have the MSG_DONTWAIT flag
if result.as_ref().err() == Some(&Errno::EWOULDBLOCK)
&& !flags.contains(MsgFlags::MSG_DONTWAIT)
{
// if the syscall would block but the file's reading has been shut down, return EOF
if socket_ref.shutdown_status.contains(ShutdownFlags::READ) {
return Ok(RecvmsgReturn {
return_val: 0,
addr: None,
msg_flags: 0,
control_len: 0,
});
}
return Err(SyscallError::new_blocked_on_file(
File::Socket(Socket::Inet(InetSocket::Udp(socket.clone()))),
FileState::READABLE,
socket_ref.supports_sa_restart(),
));
}
Ok(result?)
}
pub fn ioctl(
&mut self,
request: IoctlRequest,
arg_ptr: ForeignPtr<()>,
mem: &mut MemoryManager,
) -> SyscallResult {
match request {
// equivalent to SIOCINQ
IoctlRequest::FIONREAD => {
let len = self
.recv_buffer
.peek_message()
.map(|m| m.0.len())
.unwrap_or(0)
.try_into()
.unwrap();
let arg_ptr = arg_ptr.cast::<libc::c_int>();
mem.write(arg_ptr, &len)?;
Ok(0.into())
}
// equivalent to SIOCOUTQ
IoctlRequest::TIOCOUTQ => {
let len = self.send_buffer.len_bytes().try_into().unwrap();
let arg_ptr = arg_ptr.cast::<libc::c_int>();
mem.write(arg_ptr, &len)?;
Ok(0.into())
}
IoctlRequest::SIOCGSTAMP => {
// socket(7): "Return a struct timeval with the receive timestamp of the last packet
// passed to the user. [...] This ioctl should only be used if the socket option
// SO_TIMESTAMP is not set on the socket. Otherwise, it returns the timestamp of the
// last packet that was received while SO_TIMESTAMP was not set, or it fails if no
// such packet has been received, (i.e., ioctl(2) returns -1 with errno set to
// ENOENT)."
let Some(last_recv_time) = self.recv_time_of_last_read_packet else {
return Err(Errno::ENOENT.into());
};
let last_recv_time = (last_recv_time - EmulatedTime::UNIX_EPOCH)
.try_into()
.unwrap();
let arg_ptr = arg_ptr.cast::<libc::timeval>();
mem.write(arg_ptr, &last_recv_time)?;
Ok(0.into())
}
IoctlRequest::FIONBIO => {
panic!("This should have been handled by the ioctl syscall handler");
}
IoctlRequest::TCGETS
| IoctlRequest::TCSETS
| IoctlRequest::TCSETSW
| IoctlRequest::TCSETSF
| IoctlRequest::TCGETA
| IoctlRequest::TCSETA
| IoctlRequest::TCSETAW
| IoctlRequest::TCSETAF
| IoctlRequest::TIOCGWINSZ
| IoctlRequest::TIOCSWINSZ => {
// not a terminal
Err(Errno::ENOTTY.into())
}
request => {
warn_once_then_debug!(
"We do not yet handle ioctl request {request:?} on tcp sockets"
);
Err(Errno::EINVAL.into())
}
}
}
pub fn stat(&self) -> Result<linux_api::stat::stat, SyscallError> {
warn_once_then_debug!("We do not yet handle stat calls on udp sockets");
Err(Errno::EINVAL.into())
}
pub fn listen(
_socket: &Arc<AtomicRefCell<Self>>,
_backlog: i32,
_net_ns: &NetworkNamespace,
_rng: impl rand::Rng,
_cb_queue: &mut CallbackQueue,
) -> Result<(), Errno> {
Err(Errno::EOPNOTSUPP)
}
pub fn connect(
socket: &Arc<AtomicRefCell<Self>>,
peer_addr: &SockaddrStorage,
net_ns: &NetworkNamespace,
rng: impl rand::Rng,
_cb_queue: &mut CallbackQueue,
) -> Result<(), SyscallError> {
// if not an inet socket address
// TODO: handle an AF_UNSPEC socket address
let Some(peer_addr) = peer_addr.as_inet() else {
return Err(Errno::EINVAL.into());
};
let mut peer_addr: std::net::SocketAddrV4 = (*peer_addr).into();
// https://stackoverflow.com/a/22425796
if peer_addr.ip().is_unspecified() {
peer_addr.set_ip(std::net::Ipv4Addr::LOCALHOST);
}
// NOTE: it would be nice to use `Ipv4Addr::is_loopback` in this code rather than comparing
// to `Ipv4Addr::LOCALHOST`, but the rest of Shadow probably can't handle other loopback
// addresses (ex: 127.0.0.2) and it's probably best not to change this behaviour
// make sure we will be able to route this later
// TODO: UDP sockets probably shouldn't return `ECONNREFUSED`
if peer_addr.ip() != &std::net::Ipv4Addr::LOCALHOST {
let is_routable =
Worker::is_routable(net_ns.default_ip.into(), (*peer_addr.ip()).into());
if !is_routable {
// can't route it - there is no node with this address
log::warn!(
"Attempting to connect to address '{peer_addr}' for which no host exists"
);
return Err(Errno::ECONNREFUSED.into());
}
}
// make sure that we're bound
{
let mut socket_ref = socket.borrow_mut();
if let Some(bound_addr) = socket_ref.bound_addr {
// we must have an association since we're bound
assert!(socket_ref.association.is_some());
// make sure the new peer address is connectable from the bound interface
if !bound_addr.ip().is_unspecified() {
// assume that a socket bound to 0.0.0.0 can connect anywhere, so only check
// localhost
match (
bound_addr.ip() == &Ipv4Addr::LOCALHOST,
peer_addr.ip() == &Ipv4Addr::LOCALHOST,
) {
// bound and peer on loopback interface
(true, true) => {}
// neither bound nor peer on loopback interface (shadow treats any
// non-127.0.0.1 address as an "internet" address)
(false, false) => {}
_ => return Err(Errno::EINVAL.into()),
}
}
} else {
// we can't be unbound but have a peer
assert!(socket_ref.peer_addr.is_none());
assert!(socket_ref.association.is_none());
// implicit bind (use default interface unless the remote peer is on loopback)
let local_addr = if peer_addr.ip() == &std::net::Ipv4Addr::LOCALHOST {
SocketAddrV4::new(Ipv4Addr::LOCALHOST, 0)
} else {
SocketAddrV4::new(net_ns.default_ip, 0)
};
// this will allow us to receive packets from any source address, but
// `push_in_packet` should drop any packets that aren't from the peer
let unspecified_addr = SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, 0);
let (local_addr, handle) = super::associate_socket(
InetSocket::Udp(Arc::clone(socket)),
local_addr,
unspecified_addr,
/* check_generic_peer= */ true,
net_ns,
rng,
)?;
socket_ref.bound_addr = Some(local_addr);
socket_ref.association = Some(handle);
}
socket_ref.peer_addr = Some(peer_addr);
}
Ok(())
}
pub fn accept(
&mut self,
_net_ns: &NetworkNamespace,
_rng: impl rand::Rng,
_cb_queue: &mut CallbackQueue,
) -> Result<OpenFile, SyscallError> {
Err(Errno::EOPNOTSUPP.into())
}
pub fn shutdown(
&mut self,
how: Shutdown,
_cb_queue: &mut CallbackQueue,
) -> Result<(), SyscallError> {
// TODO: what if we set a peer, then unset the peer, then call shutdown?
if self.peer_addr.is_none() {
return Err(Errno::ENOTCONN.into());
}
if how == Shutdown::SHUT_WR || how == Shutdown::SHUT_RDWR {
// writing has been shut down
self.shutdown_status.insert(ShutdownFlags::WRITE)
}
if how == Shutdown::SHUT_RD || how == Shutdown::SHUT_RDWR {
// reading has been shut down
self.shutdown_status.insert(ShutdownFlags::READ)
}
Ok(())
}
pub fn getsockopt(
&mut self,
level: libc::c_int,
optname: libc::c_int,
optval_ptr: ForeignPtr<()>,
optlen: libc::socklen_t,
mem: &mut MemoryManager,
_cb_queue: &mut CallbackQueue,
) -> Result<libc::socklen_t, SyscallError> {
match (level, optname) {
(libc::SOL_SOCKET, libc::SO_SNDBUF) => {
let sndbuf_size = self.send_buffer.soft_limit_bytes().try_into().unwrap();
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &sndbuf_size, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, libc::SO_RCVBUF) => {
let rcvbuf_size = self.recv_buffer.soft_limit_bytes().try_into().unwrap();
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &rcvbuf_size, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, libc::SO_ERROR) => {
let error = 0;
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &error, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, libc::SO_DOMAIN) => {
let domain = libc::AF_INET;
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &domain, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, libc::SO_TYPE) => {
let sock_type = libc::SOCK_DGRAM;
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &sock_type, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, libc::SO_PROTOCOL) => {
let protocol = libc::IPPROTO_UDP;
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &protocol, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, libc::SO_ACCEPTCONN) => {
let optval_ptr = optval_ptr.cast::<libc::c_int>();
let bytes_written = write_partial(mem, &0, optval_ptr, optlen as usize)?;
Ok(bytes_written as libc::socklen_t)
}
(libc::SOL_SOCKET, _) => {
log_once_per_value_at_level!(
(level, optname),
(i32, i32),
log::Level::Warn,
log::Level::Debug,
"getsockopt called with unsupported level {level} and opt {optname}"
);
Err(Errno::ENOPROTOOPT.into())
}
_ => {
log_once_per_value_at_level!(
(level, optname),
(i32, i32),
log::Level::Warn,
log::Level::Debug,
"getsockopt called with unsupported level {level} and opt {optname}"
);
Err(Errno::EOPNOTSUPP.into())
}
}
}
pub fn setsockopt(
&mut self,
level: libc::c_int,
optname: libc::c_int,
optval_ptr: ForeignPtr<()>,
optlen: libc::socklen_t,
mem: &MemoryManager,
) -> Result<(), SyscallError> {
match (level, optname) {
(libc::SOL_SOCKET, libc::SO_SNDBUF) => {
type OptType = libc::c_int;
if usize::try_from(optlen).unwrap() < std::mem::size_of::<OptType>() {
return Err(Errno::EINVAL.into());
}
let optval_ptr = optval_ptr.cast::<OptType>();
let val: u64 = mem.read(optval_ptr)?.try_into().or(Err(Errno::EINVAL))?;
// linux kernel doubles this value upon setting
let val = val * 2;
// Linux also has limits SOCK_MIN_SNDBUF (slightly greater than 4096) and the sysctl
// max limit. We choose a reasonable lower limit for Shadow. The minimum limit in
// man 7 socket is incorrect.
let val = std::cmp::max(val, 4096);
// This upper limit was added as an arbitrarily high number so that we don't change
// Shadow's behaviour, but also prevents an application from setting this to
// something unnecessarily large like INT_MAX.
let val = std::cmp::min(val, 268435456); // 2^28 = 256 MiB
self.send_buffer
.set_soft_limit_bytes(val.try_into().unwrap());
}
(libc::SOL_SOCKET, libc::SO_RCVBUF) => {
type OptType = libc::c_int;
if usize::try_from(optlen).unwrap() < std::mem::size_of::<OptType>() {
return Err(Errno::EINVAL.into());
}
let optval_ptr = optval_ptr.cast::<OptType>();
let val: u64 = mem.read(optval_ptr)?.try_into().or(Err(Errno::EINVAL))?;
// linux kernel doubles this value upon setting
let val = val * 2;
// Linux also has limits SOCK_MIN_RCVBUF (slightly greater than 2048) and the sysctl
// max limit. We choose a reasonable lower limit for Shadow. The minimum limit in
// man 7 socket is incorrect.
let val = std::cmp::max(val, 2048);
// This upper limit was added as an arbitrarily high number so that we don't change
// Shadow's behaviour, but also prevents an application from setting this to
// something unnecessarily large like INT_MAX.
let val = std::cmp::min(val, 268435456); // 2^28 = 256 MiB
self.recv_buffer
.set_soft_limit_bytes(val.try_into().unwrap());
}
(libc::SOL_SOCKET, libc::SO_REUSEADDR) => {
// TODO: implement this
warn_once_then_debug!("setsockopt SO_REUSEADDR not yet implemented for udp");
return Err(Errno::ENOPROTOOPT.into());
}
(libc::SOL_SOCKET, libc::SO_REUSEPORT) => {
// TODO: implement this
warn_once_then_debug!("setsockopt SO_REUSEPORT not yet implemented for udp");
return Err(Errno::ENOPROTOOPT.into());
}
(libc::SOL_SOCKET, libc::SO_KEEPALIVE) => {
// TODO: implement this
warn_once_then_debug!("setsockopt SO_KEEPALIVE not yet implemented for udp");
return Err(Errno::ENOPROTOOPT.into());
}
(libc::SOL_SOCKET, libc::SO_BROADCAST) => {
// TODO: implement this, pkg.go.dev/net uses it
warn_once_then_debug!(
"setsockopt SO_BROADCAST not yet implemented for udp; ignoring and returning 0"
);
}
_ => {
log_once_per_value_at_level!(
(level, optname),
(i32, i32),
log::Level::Warn,
log::Level::Debug,
"setsockopt called with unsupported level {level} and opt {optname}"
);
return Err(Errno::ENOPROTOOPT.into());
}
}
Ok(())
}
pub fn add_listener(
&mut self,
monitoring_state: FileState,
monitoring_signals: FileSignals,
filter: StateListenerFilter,
notify_fn: impl Fn(FileState, FileState, FileSignals, &mut CallbackQueue)
+ Send
+ Sync
+ 'static,
) -> StateListenHandle {
self.event_source
.add_listener(monitoring_state, monitoring_signals, filter, notify_fn)
}
pub fn add_legacy_listener(&mut self, ptr: HostTreePointer<c::StatusListener>) {
self.event_source.add_legacy_listener(ptr);
}
pub fn remove_legacy_listener(&mut self, ptr: *mut c::StatusListener) {
self.event_source.remove_legacy_listener(ptr);
}
pub fn state(&self) -> FileState {
self.state
}
fn refresh_readable_writable(&mut self, signals: FileSignals, cb_queue: &mut CallbackQueue) {
let readable = !self.recv_buffer.is_empty();
let writable = self.send_buffer.has_space();
let readable = readable.then_some(FileState::READABLE).unwrap_or_default();
let writable = writable.then_some(FileState::WRITABLE).unwrap_or_default();
self.update_state(
/* mask= */ FileState::READABLE | FileState::WRITABLE,
readable | writable,
signals,
cb_queue,
);
}
fn update_state(
&mut self,
mask: FileState,
state: FileState,
signals: FileSignals,
cb_queue: &mut CallbackQueue,
) {
let old_state = self.state;
// remove the masked flags, then copy the masked flags
self.state.remove(mask);
self.state.insert(state & mask);
self.handle_state_change(old_state, signals, cb_queue);
}
fn handle_state_change(
&mut self,
old_state: FileState,
signals: FileSignals,
cb_queue: &mut CallbackQueue,
) {
let states_changed = self.state ^ old_state;
// if nothing changed
if states_changed.is_empty() && signals.is_empty() {
return;
}
self.event_source
.notify_listeners(self.state, states_changed, signals, cb_queue);
}
}
/// Non-payload data for a message in the send buffer.
#[derive(Debug)]
struct MessageSendHeader {
/// The source address (typically the bind address). The application can theoretically use
/// `IP_PKTINFO` to set a per-message source address.
src: SocketAddrV4,
/// The destination address (for example the peer).
dst: SocketAddrV4,
/// The priority for the packet that we'll create in the future, given to us by the host.
packet_priority: FifoPacketPriority,
}
/// Non-payload data for a message in the receive buffer.
#[derive(Debug)]
struct MessageRecvHeader {
/// The source address (for example the peer).
src: SocketAddrV4,
/// The destination address (typically the bind address). The application can theoretically use
/// `IP_PKTINFO` to get the packet destination address.
#[allow(dead_code)]
dst: SocketAddrV4,
/// The time when the network interface received the message.
recv_time: EmulatedTime,
}
/// A buffer of UDP messages and message headers.
#[derive(Debug)]
struct MessageBuffer<Hdr> {
/// The message payloads and headers.
// use a `LinkedList` so that socket buffers can shrink when they're empty (as opposed to
// `VecDeque`)
buffer: LinkedList<(Bytes, Hdr)>,
/// The number of payload bytes in this socket.
len_bytes: usize,
/// A soft limit for the maximum number of payload bytes this buffer can hold.
soft_limit_bytes: usize,
}
impl<Hdr> MessageBuffer<Hdr> {
pub fn new(soft_limit_bytes: usize) -> Self {
Self {
buffer: std::collections::LinkedList::new(),
len_bytes: 0,
soft_limit_bytes,
}
}
/// Push a message to the buffer. Returns the message and header as an `Err` if there wasn't
/// enough space.
pub fn push_message(&mut self, message: Bytes, header: Hdr) -> Result<(), (Bytes, Hdr)> {
// TODO: i think udp allows at most one packet to exceed the buffer capacity; should confirm
// this
if !self.has_space() {
return Err((message, header));
}
// TODO: on linux the socket buffer length also takes into account any header and struct
// overhead, otherwise the buffer would take an infinite amount of 0-len packets
self.len_bytes += message.len();
self.buffer.push_back((message, header));
Ok(())
}
/// Pop the next message from the buffer. Returns a tuple of the message bytes and message
/// header.
pub fn pop_message(&mut self) -> Option<(Bytes, Hdr)> {
let (message, header) = self.buffer.pop_front()?;
self.len_bytes -= message.len();
Some((message, header))
}
/// Peek the next message in the buffer.
pub fn peek_message(&self) -> Option<&(Bytes, Hdr)> {
self.buffer.front()
}
/// The number of payload bytes contained in the buffer. A length of 0 does not mean that the
/// buffer is empty.
pub fn len_bytes(&self) -> usize {
self.len_bytes
}
/// Is there space for at least one more packet?
pub fn has_space(&self) -> bool {
self.len_bytes < self.soft_limit_bytes
}
/// Is the buffer empty (does it have 0 packets)?
pub fn is_empty(&self) -> bool {
self.buffer.is_empty()
}
/// The soft limit for the size of the buffer.
pub fn soft_limit_bytes(&self) -> usize {
self.soft_limit_bytes
}
/// Set the soft limit for the size of the buffer.
pub fn set_soft_limit_bytes(&mut self, soft_limit_bytes: usize) {
self.soft_limit_bytes = soft_limit_bytes;
}
}