3 files changed, 170 insertions, 28 deletions
diff --git a/library/std/src/sys/net/connection/uefi/mod.rs b/library/std/src/sys/net/connection/uefi/mod.rs
index da217439626..46d67c8e510 100644
--- a/library/std/src/sys/net/connection/uefi/mod.rs
+++ b/library/std/src/sys/net/connection/uefi/mod.rs
@@ -4,11 +4,14 @@ use crate::net::{Ipv4Addr, Ipv6Addr, Shutdown, SocketAddr};
 use crate::sys::unsupported;
 use crate::time::Duration;
 
-pub struct TcpStream(!);
+mod tcp;
+pub(crate) mod tcp4;
+
+pub struct TcpStream(#[expect(dead_code)] tcp::Tcp);
 
 impl TcpStream {
-    pub fn connect(_: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
-        unsupported()
+    pub fn connect(addr: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
+        tcp::Tcp::connect(addr?).map(Self)
     }
 
     pub fn connect_timeout(_: &SocketAddr, _: Duration) -> io::Result<TcpStream> {
@@ -16,105 +19,105 @@ impl TcpStream {
     }
 
     pub fn set_read_timeout(&self, _: Option<Duration>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn set_write_timeout(&self, _: Option<Duration>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn read_timeout(&self) -> io::Result<Option<Duration>> {
-        self.0
+        unsupported()
     }
 
     pub fn write_timeout(&self) -> io::Result<Option<Duration>> {
-        self.0
+        unsupported()
     }
 
     pub fn peek(&self, _: &mut [u8]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn read(&self, _: &mut [u8]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn read_buf(&self, _buf: BorrowedCursor<'_>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn read_vectored(&self, _: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn is_read_vectored(&self) -> bool {
-        self.0
+        false
     }
 
     pub fn write(&self, _: &[u8]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn write_vectored(&self, _: &[IoSlice<'_>]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn is_write_vectored(&self) -> bool {
-        self.0
+        false
     }
 
     pub fn peer_addr(&self) -> io::Result<SocketAddr> {
-        self.0
+        unsupported()
     }
 
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
-        self.0
+        unsupported()
     }
 
     pub fn shutdown(&self, _: Shutdown) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn duplicate(&self) -> io::Result<TcpStream> {
-        self.0
+        unsupported()
     }
 
     pub fn set_linger(&self, _: Option<Duration>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn linger(&self) -> io::Result<Option<Duration>> {
-        self.0
+        unsupported()
     }
 
     pub fn set_nodelay(&self, _: bool) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn nodelay(&self) -> io::Result<bool> {
-        self.0
+        unsupported()
     }
 
     pub fn set_ttl(&self, _: u32) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn ttl(&self) -> io::Result<u32> {
-        self.0
+        unsupported()
     }
 
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
-        self.0
+        unsupported()
     }
 
     pub fn set_nonblocking(&self, _: bool) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 }
 
 impl fmt::Debug for TcpStream {
     fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0
+        todo!()
     }
 }
 
diff --git a/library/std/src/sys/net/connection/uefi/tcp.rs b/library/std/src/sys/net/connection/uefi/tcp.rs
new file mode 100644
index 00000000000..f87accdc41d
--- /dev/null
+++ b/library/std/src/sys/net/connection/uefi/tcp.rs
@@ -0,0 +1,21 @@
+use super::tcp4;
+use crate::io;
+use crate::net::SocketAddr;
+
+pub(crate) enum Tcp {
+    V4(#[expect(dead_code)] tcp4::Tcp4),
+}
+
+impl Tcp {
+    pub(crate) fn connect(addr: &SocketAddr) -> io::Result<Self> {
+        match addr {
+            SocketAddr::V4(x) => {
+                let temp = tcp4::Tcp4::new()?;
+                temp.configure(true, Some(x), None)?;
+                temp.connect()?;
+                Ok(Tcp::V4(temp))
+            }
+            SocketAddr::V6(_) => todo!(),
+        }
+    }
+}
diff --git a/library/std/src/sys/net/connection/uefi/tcp4.rs b/library/std/src/sys/net/connection/uefi/tcp4.rs
new file mode 100644
index 00000000000..f7ca373b52b
--- /dev/null
+++ b/library/std/src/sys/net/connection/uefi/tcp4.rs
@@ -0,0 +1,118 @@
+use r_efi::efi::{self, Status};
+use r_efi::protocols::tcp4;
+
+use crate::io;
+use crate::net::SocketAddrV4;
+use crate::ptr::NonNull;
+use crate::sync::atomic::{AtomicBool, Ordering};
+use crate::sys::pal::helpers;
+
+const TYPE_OF_SERVICE: u8 = 8;
+const TIME_TO_LIVE: u8 = 255;
+
+pub(crate) struct Tcp4 {
+    protocol: NonNull<tcp4::Protocol>,
+    flag: AtomicBool,
+    #[expect(dead_code)]
+    service_binding: helpers::ServiceProtocol,
+}
+
+const DEFAULT_ADDR: efi::Ipv4Address = efi::Ipv4Address { addr: [0u8; 4] };
+
+impl Tcp4 {
+    pub(crate) fn new() -> io::Result<Self> {
+        let service_binding = helpers::ServiceProtocol::open(tcp4::SERVICE_BINDING_PROTOCOL_GUID)?;
+        let protocol = helpers::open_protocol(service_binding.child_handle(), tcp4::PROTOCOL_GUID)?;
+
+        Ok(Self { service_binding, protocol, flag: AtomicBool::new(false) })
+    }
+
+    pub(crate) fn configure(
+        &self,
+        active: bool,
+        remote_address: Option<&SocketAddrV4>,
+        station_address: Option<&SocketAddrV4>,
+    ) -> io::Result<()> {
+        let protocol = self.protocol.as_ptr();
+
+        let (remote_address, remote_port) = if let Some(x) = remote_address {
+            (helpers::ipv4_to_r_efi(*x.ip()), x.port())
+        } else {
+            (DEFAULT_ADDR, 0)
+        };
+
+        // FIXME: Remove when passive connections with proper subnet handling are added
+        assert!(station_address.is_none());
+        let use_default_address = efi::Boolean::TRUE;
+        let (station_address, station_port) = (DEFAULT_ADDR, 0);
+        let subnet_mask = helpers::ipv4_to_r_efi(crate::net::Ipv4Addr::new(0, 0, 0, 0));
+
+        let mut config_data = tcp4::ConfigData {
+            type_of_service: TYPE_OF_SERVICE,
+            time_to_live: TIME_TO_LIVE,
+            access_point: tcp4::AccessPoint {
+                use_default_address,
+                remote_address,
+                remote_port,
+                active_flag: active.into(),
+                station_address,
+                station_port,
+                subnet_mask,
+            },
+            control_option: crate::ptr::null_mut(),
+        };
+
+        let r = unsafe { ((*protocol).configure)(protocol, &mut config_data) };
+        if r.is_error() { Err(crate::io::Error::from_raw_os_error(r.as_usize())) } else { Ok(()) }
+    }
+
+    pub(crate) fn connect(&self) -> io::Result<()> {
+        let evt = unsafe { self.create_evt() }?;
+        let completion_token =
+            tcp4::CompletionToken { event: evt.as_ptr(), status: Status::SUCCESS };
+
+        let protocol = self.protocol.as_ptr();
+        let mut conn_token = tcp4::ConnectionToken { completion_token };
+
+        let r = unsafe { ((*protocol).connect)(protocol, &mut conn_token) };
+        if r.is_error() {
+            return Err(io::Error::from_raw_os_error(r.as_usize()));
+        }
+
+        self.wait_for_flag();
+
+        if completion_token.status.is_error() {
+            Err(io::Error::from_raw_os_error(completion_token.status.as_usize()))
+        } else {
+            Ok(())
+        }
+    }
+
+    unsafe fn create_evt(&self) -> io::Result<helpers::OwnedEvent> {
+        self.flag.store(false, Ordering::Relaxed);
+        helpers::OwnedEvent::new(
+            efi::EVT_NOTIFY_SIGNAL,
+            efi::TPL_CALLBACK,
+            Some(toggle_atomic_flag),
+            Some(unsafe { NonNull::new_unchecked(self.flag.as_ptr().cast()) }),
+        )
+    }
+
+    fn wait_for_flag(&self) {
+        while !self.flag.load(Ordering::Relaxed) {
+            let _ = self.poll();
+        }
+    }
+
+    fn poll(&self) -> io::Result<()> {
+        let protocol = self.protocol.as_ptr();
+        let r = unsafe { ((*protocol).poll)(protocol) };
+
+        if r.is_error() { Err(io::Error::from_raw_os_error(r.as_usize())) } else { Ok(()) }
+    }
+}
+
+extern "efiapi" fn toggle_atomic_flag(_: r_efi::efi::Event, ctx: *mut crate::ffi::c_void) {
+    let flag = unsafe { AtomicBool::from_ptr(ctx.cast()) };
+    flag.store(true, Ordering::Relaxed);
+}