feat: TCP socket support using LibUV

src/Std/Net/Tcp.lean

@@ -0,0 +1,89 @@
+/-
+Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Henrik Böving, Sofia Rodrigues.
+-/
+prelude
+import Init.Data.SInt
+import Std.Net.Addr
+import Init.System
+
+namespace Std
+namespace Net
+
+private opaque TcpSocketImpl : NonemptyType.{0}
+
+/--
+Represents a TCP socket.
+-/
+def TcpSocket : Type := TcpSocketImpl.type
+
+instance : Nonempty TcpSocket := TcpSocketImpl.property
+
+namespace TcpSocket
+
+/--
+Creates a new TCP socket.
+-/
+@[extern "lean_uv_tcp_new"]
+opaque new : IO TcpSocket
+
+/--
+Connect a TCP socket to the specified address.
+-/
+@[extern "lean_uv_tcp_connect"]
+opaque connect (socket : TcpSocket) (addr : SocketAddress) : IO (IO.Promise (Except String Unit))
+
+/--
+Send data through a TCP socket.
+-/
+@[extern "lean_uv_tcp_send"]
+opaque send (socket : TcpSocket) (data : ByteArray) : IO (IO.Promise (Except IO.Error Unit))
+
+/--
+Receive data from a TCP socket.
+-/
+@[extern "lean_uv_tcp_recv"]
+opaque recv (socket : TcpSocket) : IO (IO.Promise (Except IO.Error ByteArray))
+
+/--
+Bind a TCP socket to a specific address.
+-/
+@[extern "lean_uv_tcp_bind"]
+opaque bind (socket : TcpSocket) (addr : SocketAddress) : IO Unit
+
+/--
+Start listening for incoming connections on a TCP socket.
+-/
+@[extern "lean_uv_tcp_listen"]
+opaque listen (socket : TcpSocket) (backlog : Int32) : IO Unit
+
+/--
+Accept an incoming connection on a listening TCP socket.
+-/
+@[extern "lean_uv_tcp_accept"]
+opaque accept (socket : TcpSocket) : IO (IO.Promise (Except IO.Error TcpSocket))
+
+/--
+Get the remote address of a connected TCP socket.
+-/
+@[extern "lean_uv_tcp_getpeername"]
+opaque getpeername (socket : TcpSocket) : IO SockAddr
+
+/--
+Get the local address of a bound TCP socket.
+-/
+@[extern "lean_uv_tcp_getsockname"]
+opaque getsockname (socket : TcpSocket) : IO SockAddr
+
+/--
+Enable or disable the Nagle algorithm for a TCP socket.
+-/
+@[extern "lean_uv_tcp_nodelay"]
+opaque nodelay (socket : TcpSocket) : IO Unit
+
+/--
+Enable or disable TCP keep-alive for a socket.
+-/
+@[extern "lean_uv_tcp_keepalive"]
+opaque keepalive (socket : TcpSocket) (enable : Int32) (delay : UInt32) : IO Unit

src/runtime/CMakeLists.txt

@@ -3,7 +3,7 @@ object.cpp apply.cpp exception.cpp interrupt.cpp memory.cpp
 stackinfo.cpp compact.cpp init_module.cpp load_dynlib.cpp io.cpp hash.cpp
 platform.cpp alloc.cpp allocprof.cpp sharecommon.cpp stack_overflow.cpp
 process.cpp object_ref.cpp mpn.cpp mutex.cpp libuv.cpp uv/net_addr.cpp uv/event_loop.cpp
-uv/timer.cpp)
+uv/timer.cpp uv/tcp.cpp)
 add_library(leanrt_initial-exec STATIC ${RUNTIME_OBJS})
 set_target_properties(leanrt_initial-exec PROPERTIES
   ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})

src/runtime/libuv.cpp

@@ -15,6 +15,7 @@ namespace lean {
 
 extern "C" void initialize_libuv() {
     initialize_libuv_timer();
+    initialize_libuv_tcp_socket();
     initialize_libuv_loop();
 
     lthread([]() { event_loop_run_loop(&global_ev); });

src/runtime/libuv.h

@@ -7,7 +7,8 @@ Author: Markus Himmel, Sofia Rodrigues
 #pragma once
 #include <lean/lean.h>
 #include "runtime/uv/event_loop.h"
- #include "runtime/uv/timer.h"
+#include "runtime/uv/timer.h"
+#include "runtime/uv/tcp.h"
 #include "runtime/alloc.h"
 #include "runtime/io.h"
 #include "runtime/utf8.h"

src/runtime/uv/net_addr.cpp

@@ -28,6 +28,22 @@ void lean_ipv6_addr_to_in6_addr(b_obj_arg ipv6_addr, in6_addr* out) {
     }
 }
 
+extern "C" void lean_socket_addr_to_sockaddr(b_obj_arg ip_addr, struct sockaddr_in* out) {
+    lean_object * socket_addr_obj = lean_ctor_get(ip_addr, 0);
+    lean_object * ip_addr_obj = lean_ctor_get(socket_addr_obj, 0);
+    uint16_t port_obj = lean_ctor_get_uint16(socket_addr_obj, sizeof(void*)*1);
+
+    if (lean_ptr_tag(ip_addr) == 0) {
+        lean_ipv4_addr_to_in_addr(ip_addr_obj, &out->sin_addr);
+        out->sin_family = AF_INET;
+    } else {
+        lean_ipv6_addr_to_in6_addr(ip_addr_obj, (in6_addr*)&out->sin_addr);
+        out->sin_family = AF_INET6;
+    }
+
+    out->sin_port = htons(port_obj);
+}
+
 lean_obj_res lean_in_addr_to_ipv4_addr(const in_addr* ipv4_addr) {
     obj_res ret = alloc_array(0, 4);
     uint32_t hostaddr = ntohl(ipv4_addr->s_addr);

src/runtime/uv/net_addr.h

@@ -15,6 +15,7 @@ namespace lean {
 
 void lean_ipv4_addr_to_in_addr(b_obj_arg ipv4_addr, struct in_addr* out);
 void lean_ipv6_addr_to_in6_addr(b_obj_arg ipv6_addr, struct in6_addr* out);
+extern "C" void lean_socket_addr_to_sockaddr(b_obj_arg ip_addr, struct sockaddr_in* out);
 lean_obj_res lean_in_addr_to_ipv4_addr(const struct in_addr* ipv4_addr);
 lean_obj_res lean_in6_addr_to_ipv6_addr(const struct in6_addr* ipv6_addr);