Skip to content

Commit

Permalink
simplify retrieval of connection address from dns_cache.
Browse files Browse the repository at this point in the history
  • Loading branch information
@meowjesty
meowjesty committed Aug 18, 2023
1 parent c7782fb commit 219574d
Showing 1 changed file with 38 additions and 62 deletions.
100 changes: 38 additions & 62 deletions mirrord/layer/src/socket.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -345,6 +345,9 @@ impl OutgoingSelector {
/// Checks if the `address` matches the specified outgoing filter, and returns a `bool`
/// indicating if this connection should go through the remote pod, or from the local app.
///
/// Returns either a [`ConnectionThrough::Remote`] or [`ConnectionThroughLocal`], with the
/// address that should be connected to.
///
/// ## `remote`
///
/// When the user specifies something like `remote = [":7777"]`, we're going to check if
Expand All @@ -354,9 +357,8 @@ impl OutgoingSelector {
/// ## `local`
///
/// Basically the same thing as `remote`, but the result is reversed, meaning that, if
/// `address` matches something specified in `local = [":7777"]`, then _negate_ it and return
/// `false`, meaning we return "do not connect remote" (or "connect local" if you prefer
/// positive thinking).
/// `address` matches something specified in `local = [":7777"]`, then we return a
/// [`ConnectionThrough::Local`].
///
/// ## Filter rules
///
Expand All @@ -372,18 +374,20 @@ impl OutgoingSelector {
&self,
address: SocketAddr,
) -> Detour<ConnectionThrough> {
// Closure that checks if the current filter matches the enabled protocols.
let filter_protocol = |outgoing: &&OutgoingFilter| match outgoing.protocol {
ProtocolFilter::Any => true,
ProtocolFilter::Tcp if PROTOCOL == TCP => true,
ProtocolFilter::Udp if PROTOCOL == UDP => true,
_ => false,
};

// Closure to skip hostnames, as these filters will be dealt with after being resolved.
let skip_unresolved =
|outgoing: &&OutgoingFilter| !matches!(outgoing.address, AddressFilter::Name(_));

// Closure that tries to match `address` with something in the selector set.
let any_address = |outgoing: &OutgoingFilter| match outgoing.address {
let select_address = |outgoing: &OutgoingFilter| match outgoing.address {
AddressFilter::Socket(select_address) => ((select_address.ip().is_unspecified()
&& select_address.port() == 0)
|| (select_address.ip().is_unspecified()
Expand All @@ -399,64 +403,25 @@ impl OutgoingSelector {
.then_some(address),
};

// Resolve the hostnames in the filter.
let resolved_hosts = match &self {
OutgoingSelector::Unfiltered => HashSet::default(),
OutgoingSelector::Remote(_) => self.resolve_dns::<true>()?,
OutgoingSelector::Local(_) => self.resolve_dns::<false>()?,
};
let hosts = resolved_hosts.iter();

// let resolve_dns_locally = || {
// if let Some((cached_hostname, port)) = DNS_CACHE
// .get(&SocketAddr::from((address.ip(), 0)))
// .map(|addr| (addr.value().clone(), address.port()))
// {
// debug!("Resolving address locally [{cached_hostname:?}]");
// let _guard = DetourGuard::new();
// let locally_resolved = format!("{cached_hostname}:{port}")
// .to_socket_addrs()?
// .find(SocketAddr::is_ipv4)?;

// debug!("resolved address {locally_resolved:#?}");
// Ok::<_, HookError>(ConnectionThrough::Local(locally_resolved))
// } else {
// Ok::<_, HookError>(ConnectionThrough::Local(selected_address))
// }?
// };

Detour::Success(match self {
OutgoingSelector::Unfiltered => ConnectionThrough::Remote(address),

// TODO(alex) [high] 2023-08-17: If we have config `port = 8888`, and this
// connection has port `7777`, then we don't match on the remote
// filter, which means this returns empty option.
//
// `None` turns into bypass, which calls `FN_CONNECT(resolved_address:7777)`, which
// is the wrong address, as it resolved in the cluster! We have to resolve the
// address locally in this case.
OutgoingSelector::Remote(list) => {
if let None = list

Check failure on line 417 in mirrord/layer/src/socket.rs

View workflow job for this annotation

GitHub Actions / lint_macos 

redundant pattern matching, consider using `is_none()`

Check failure on line 417 in mirrord/layer/src/socket.rs

View workflow job for this annotation

GitHub Actions / lint 

redundant pattern matching, consider using `is_none()`
.iter()
.filter(skip_unresolved)
.chain(hosts)
.filter(filter_protocol)
.find_map(any_address)
.find_map(select_address)
{
if let Some((cached_hostname, port)) = DNS_CACHE
.get(&SocketAddr::from((address.ip(), 0)))
.map(|addr| (addr.value().clone(), address.port()))
{
debug!("remote filter: Resolving address locally [{cached_hostname:?}]");
let _guard = DetourGuard::new();
let locally_resolved = format!("{cached_hostname}:{port}")
.to_socket_addrs()?
.find(SocketAddr::is_ipv4)?;

debug!("remote filter: resolved address {locally_resolved:#?}");
Ok::<_, HookError>(ConnectionThrough::Local(locally_resolved))
} else {
Ok::<_, HookError>(ConnectionThrough::Local(address))
}?
Self::get_address_from_dns_cache::<true>(address, None)?
} else {
ConnectionThrough::Remote(address)
}
Expand All @@ -467,23 +432,9 @@ impl OutgoingSelector {
.filter(skip_unresolved)
.chain(hosts)
.filter(filter_protocol)
.find_map(any_address)
.find_map(select_address)
{
if let Some((cached_hostname, port)) = DNS_CACHE
.get(&SocketAddr::from((address.ip(), 0)))
.map(|addr| (addr.value().clone(), address.port()))
{
debug!("local filter: Resolving address locally [{cached_hostname:?}]");
let _guard = DetourGuard::new();
let locally_resolved = format!("{cached_hostname}:{port}")
.to_socket_addrs()?
.find(SocketAddr::is_ipv4)?;

debug!("local filter: resolved address {locally_resolved:#?}");
Ok::<_, HookError>(ConnectionThrough::Local(locally_resolved))
} else {
Ok::<_, HookError>(ConnectionThrough::Local(selected_address))
}?
Self::get_address_from_dns_cache::<false>(address, Some(selected_address))?
} else {
ConnectionThrough::Remote(address)
}
Expand Down Expand Up @@ -578,6 +529,31 @@ impl OutgoingSelector {
.collect()),
}
}

fn get_address_from_dns_cache<const REMOTE: bool>(
address: SocketAddr,
selected_address: Option<SocketAddr>,
) -> Detour<ConnectionThrough> {
if let Some((cached_hostname, port)) = DNS_CACHE
.get(&SocketAddr::from((address.ip(), 0)))
.map(|addr| (addr.value().clone(), address.port()))
{
debug!("filter {REMOTE:?}: Resolving address locally [{cached_hostname:?}]");
let _guard = DetourGuard::new();
let locally_resolved = format!("{cached_hostname}:{port}")
.to_socket_addrs()?
.find(SocketAddr::is_ipv4)?;

debug!("remote filter: resolved address {locally_resolved:#?}");
Detour::Success(ConnectionThrough::Local(locally_resolved))
} else {

Check failure on line 549 in mirrord/layer/src/socket.rs

View workflow job for this annotation

GitHub Actions / lint_macos 

this `else { if .. }` block can be collapsed

Check failure on line 549 in mirrord/layer/src/socket.rs

View workflow job for this annotation

GitHub Actions / lint 

this `else { if .. }` block can be collapsed
if REMOTE {
Detour::Success(ConnectionThrough::Local(address))
} else {
Detour::Success(ConnectionThrough::Local(selected_address.unwrap()))
}
}
}
}

#[inline]
Expand Down

0 comments on commit 219574d

Please sign in to comment.