Unrolled build for #145327

Rollup merge of #145327 - joboet:net-addr-sgx-hack, r=tgross35

std: make address resolution weirdness local to SGX

Currently, the implementations of `TcpStream::connect` and its cousins take an `io::Result<&SocketAddr>` as argument, which is very weird, as most of them then `?`-try the result immediately to access the actual address. This weirdness is however necessitated by a peculiarity of the SGX networking implementation:

SGX doesn't support DNS resolution but rather accepts hostnames in the same place as socket addresses. So, to make e.g.
```rust
TcpStream::connect("example.com:80")`
```
work, the DNS lookup returns a special error (`NonIpSockAddr`) instead, which contains the hostname being looked up. When `.to_socket_addrs()` fails, the `each_addr` function used to select an address will pass the error to the inner `TcpStream::connect` implementation, which in SGX's case will inspect the error and try recover the hostname from it. If
that succeeds, it continues with the found hostname.

This is pretty obviously a terrible hack and leads to buggy code (for instance, when users use the result of `.to_socket_addrs()` in their own `ToSocketAddrs` implementation to select from a list of possible URLs, the only URL used will be that of the last item tried). Still, without changes to the SGX usercall ABI, it cannot be avoided.

Therefore, this PR aims to minimise the impact of that weirdness and remove it from all non-SGX platforms. The inner `TcpStream::connect`, et al. functions now receive the `ToSocketAddrs` type directly and call `each_addr` (which is moved to `sys::net::connection`) themselves. On SGX, the implementation uses a special `each_addr` which contains the whole pass-hostname-through-error hack.

As well as making the code cleaner, this also opens up the possibility of reusing newly created sockets even if a connection request fails – but I've left that for another PR.

CC `@raoulstrackx`

Author: rust-timer

library/std/src/io/error.rs

@@ -95,6 +95,9 @@ impl Error {
 
     pub(crate) const ZERO_TIMEOUT: Self =
         const_error!(ErrorKind::InvalidInput, "cannot set a 0 duration timeout");
+
+    pub(crate) const NO_ADDRESSES: Self =
+        const_error!(ErrorKind::InvalidInput, "could not resolve to any addresses");
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

library/std/src/net/mod.rs

@@ -34,7 +34,6 @@ pub use self::tcp::IntoIncoming;
 pub use self::tcp::{Incoming, TcpListener, TcpStream};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::udp::UdpSocket;
-use crate::io::{self, ErrorKind};
 
 mod ip_addr;
 mod socket_addr;
@@ -67,23 +66,3 @@ pub enum Shutdown {
     #[stable(feature = "rust1", since = "1.0.0")]
     Both,
 }
-
-fn each_addr<A: ToSocketAddrs, F, T>(addr: A, mut f: F) -> io::Result<T>
-where
-    F: FnMut(io::Result<&SocketAddr>) -> io::Result<T>,
-{
-    let addrs = match addr.to_socket_addrs() {
-        Ok(addrs) => addrs,
-        Err(e) => return f(Err(e)),
-    };
-    let mut last_err = None;
-    for addr in addrs {
-        match f(Ok(&addr)) {
-            Ok(l) => return Ok(l),
-            Err(e) => last_err = Some(e),
-        }
-    }
-    Err(last_err.unwrap_or_else(|| {
-        io::const_error!(ErrorKind::InvalidInput, "could not resolve to any addresses")
-    }))
-}

library/std/src/net/tcp.rs

@@ -167,7 +167,7 @@ impl TcpStream {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> {
-        super::each_addr(addr, net_imp::TcpStream::connect).map(TcpStream)
+        net_imp::TcpStream::connect(addr).map(TcpStream)
     }
 
     /// Opens a TCP connection to a remote host with a timeout.
@@ -782,7 +782,7 @@ impl TcpListener {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<TcpListener> {
-        super::each_addr(addr, net_imp::TcpListener::bind).map(TcpListener)
+        net_imp::TcpListener::bind(addr).map(TcpListener)
     }
 
     /// Returns the local socket address of this listener.

library/std/src/net/tcp/tests.rs

@@ -1,5 +1,5 @@
 use crate::io::prelude::*;
-use crate::io::{BorrowedBuf, IoSlice, IoSliceMut};
+use crate::io::{BorrowedBuf, ErrorKind, IoSlice, IoSliceMut};
 use crate::mem::MaybeUninit;
 use crate::net::test::{next_test_ip4, next_test_ip6};
 use crate::net::*;

library/std/src/net/udp.rs

@@ -120,7 +120,7 @@ impl UdpSocket {
     /// [`Ipv4Addr::UNSPECIFIED`] or [`Ipv6Addr::UNSPECIFIED`].
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<UdpSocket> {
-        super::each_addr(addr, net_imp::UdpSocket::bind).map(UdpSocket)
+        net_imp::UdpSocket::bind(addr).map(UdpSocket)
     }
 
     /// Receives a single datagram message on the socket. On success, returns the number
@@ -677,7 +677,7 @@ impl UdpSocket {
     /// on the platform.
     #[stable(feature = "net2_mutators", since = "1.9.0")]
     pub fn connect<A: ToSocketAddrs>(&self, addr: A) -> io::Result<()> {
-        super::each_addr(addr, |addr| self.0.connect(addr))
+        self.0.connect(addr)
     }
 
     /// Sends data on the socket to the remote address to which it is connected.

library/std/src/net/udp/tests.rs

@@ -1,3 +1,4 @@
+use crate::io::ErrorKind;
 use crate::net::test::{compare_ignore_zoneid, next_test_ip4, next_test_ip6};
 use crate::net::*;
 use crate::sync::mpsc::channel;

library/std/src/sys/net/connection/mod.rs

@@ -0,0 +1,57 @@
+cfg_select! {
+    any(
+        all(target_family = "unix", not(target_os = "l4re")),
+        target_os = "windows",
+        target_os = "hermit",
+        all(target_os = "wasi", target_env = "p2"),
+        target_os = "solid_asp3",
+    ) => {
+        mod socket;
+        pub use socket::*;
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::*;
+    }
+    all(target_os = "wasi", target_env = "p1") => {
+        mod wasip1;
+        pub use wasip1::*;
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::*;
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        pub use uefi::*;
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::*;
+    }
+}
+
+#[cfg_attr(
+    // Make sure that this is used on some platforms at least.
+    not(any(target_os = "linux", target_os = "windows")),
+    allow(dead_code)
+)]
+fn each_addr<A: crate::net::ToSocketAddrs, F, T>(addr: A, mut f: F) -> crate::io::Result<T>
+where
+    F: FnMut(&crate::net::SocketAddr) -> crate::io::Result<T>,
+{
+    use crate::io::Error;
+
+    let mut last_err = None;
+    for addr in addr.to_socket_addrs()? {
+        match f(&addr) {
+            Ok(l) => return Ok(l),
+            Err(e) => last_err = Some(e),
+        }
+    }
+
+    match last_err {
+        Some(err) => Err(err),
+        None => Err(Error::NO_ADDRESSES),
+    }
+}

library/std/src/sys/net/connection/sgx.rs

@@ -1,11 +1,12 @@
+use crate::error;
+use crate::fmt::{self, Write};
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
 use crate::net::{Ipv4Addr, Ipv6Addr, Shutdown, SocketAddr, ToSocketAddrs};
 use crate::sync::Arc;
 use crate::sys::abi::usercalls;
 use crate::sys::fd::FileDesc;
 use crate::sys::{AsInner, FromInner, IntoInner, TryIntoInner, sgx_ineffective, unsupported};
 use crate::time::Duration;
-use crate::{error, fmt};
 
 const DEFAULT_FAKE_TTL: u32 = 64;
 
@@ -63,18 +64,52 @@ impl fmt::Debug for TcpStream {
     }
 }
 
-fn io_err_to_addr(result: io::Result<&SocketAddr>) -> io::Result<String> {
-    match result {
-        Ok(saddr) => Ok(saddr.to_string()),
-        // need to downcast twice because io::Error::into_inner doesn't return the original
-        // value if the conversion fails
-        Err(e) => {
-            if e.get_ref().and_then(|e| e.downcast_ref::<NonIpSockAddr>()).is_some() {
-                Ok(e.into_inner().unwrap().downcast::<NonIpSockAddr>().unwrap().host)
-            } else {
-                Err(e)
+/// Converts each address in `addr` into a hostname.
+///
+/// SGX doesn't support DNS resolution but rather accepts hostnames in
+/// the same place as socket addresses. So, to make e.g.
+/// ```rust
+/// TcpStream::connect("example.com:80")`
+/// ```
+/// work, the DNS lookup returns a special error (`NonIpSockAddr`) instead,
+/// which contains the hostname being looked up. When `.to_socket_addrs()`
+/// fails, we inspect the error and try recover the hostname from it. If that
+/// succeeds, we thus continue with the hostname.
+///
+/// This is a terrible hack and leads to buggy code. For instance, when users
+/// use the result of `.to_socket_addrs()` in their own `ToSocketAddrs`
+/// implementation to select from a list of possible URLs, the only URL used
+/// will be that of the last item tried.
+// FIXME: This is a terrible, terrible hack. Fixing this requires Fortanix to
+// add a method for resolving addresses.
+fn each_addr<A: ToSocketAddrs, F, T>(addr: A, mut f: F) -> io::Result<T>
+where
+    F: FnMut(&str) -> io::Result<T>,
+{
+    match addr.to_socket_addrs() {
+        Ok(addrs) => {
+            let mut last_err = None;
+            let mut encoded = String::new();
+            for addr in addrs {
+                // Format the IP address as a string, reusing the buffer.
+                encoded.clear();
+                write!(encoded, "{}", &addr).unwrap();
+
+                match f(&encoded) {
+                    Ok(val) => return Ok(val),
+                    Err(err) => last_err = Some(err),
+                }
+            }
+
+            match last_err {
+                Some(err) => Err(err),
+                None => Err(io::Error::NO_ADDRESSES),
             }
         }
+        Err(err) => match err.get_ref().and_then(|e| e.downcast_ref::<NonIpSockAddr>()) {
+            Some(NonIpSockAddr { host }) => f(host),
+            None => Err(err),
+        },
     }
 }
 
@@ -86,17 +121,18 @@ fn addr_to_sockaddr(addr: Option<&str>) -> io::Result<SocketAddr> {
 }
 
 impl TcpStream {
-    pub fn connect(addr: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
-        let addr = io_err_to_addr(addr)?;
-        let (fd, local_addr, peer_addr) = usercalls::connect_stream(&addr)?;
-        Ok(TcpStream { inner: Socket::new(fd, local_addr), peer_addr: Some(peer_addr) })
+    pub fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> {
+        each_addr(addr, |addr| {
+            let (fd, local_addr, peer_addr) = usercalls::connect_stream(addr)?;
+            Ok(TcpStream { inner: Socket::new(fd, local_addr), peer_addr: Some(peer_addr) })
+        })
     }
 
     pub fn connect_timeout(addr: &SocketAddr, dur: Duration) -> io::Result<TcpStream> {
         if dur == Duration::default() {
             return Err(io::Error::ZERO_TIMEOUT);
         }
-        Self::connect(Ok(addr)) // FIXME: ignoring timeout
+        Self::connect(addr) // FIXME: ignoring timeout
     }
 
     pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
@@ -247,10 +283,11 @@ impl fmt::Debug for TcpListener {
 }
 
 impl TcpListener {
-    pub fn bind(addr: io::Result<&SocketAddr>) -> io::Result<TcpListener> {
-        let addr = io_err_to_addr(addr)?;
-        let (fd, local_addr) = usercalls::bind_stream(&addr)?;
-        Ok(TcpListener { inner: Socket::new(fd, local_addr) })
+    pub fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<TcpListener> {
+        each_addr(addr, |addr| {
+            let (fd, local_addr) = usercalls::bind_stream(addr)?;
+            Ok(TcpListener { inner: Socket::new(fd, local_addr) })
+        })
     }
 
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
@@ -316,7 +353,7 @@ impl FromInner<Socket> for TcpListener {
 pub struct UdpSocket(!);
 
 impl UdpSocket {
-    pub fn bind(_: io::Result<&SocketAddr>) -> io::Result<UdpSocket> {
+    pub fn bind<A: ToSocketAddrs>(_: A) -> io::Result<UdpSocket> {
         unsupported()
     }
 
@@ -436,7 +473,7 @@ impl UdpSocket {
         self.0
     }
 
-    pub fn connect(&self, _: io::Result<&SocketAddr>) -> io::Result<()> {
+    pub fn connect<A: ToSocketAddrs>(&self, _: A) -> io::Result<()> {
         self.0
     }
 }