WASI VirtualSocket interface and Java networking classes implementation #998

mandesero · 2025-01-20T11:20:24Z

This pull request introduces two key updates to enhance networking capabilities in a WASI-based environment:

Patch 1: WASI: VirtualSocket Interface

This patch provides the core functionality required for socket operations within the WASI environment. Key features include:

Creating, binding, connecting, and listening to sockets.
Sending and receiving data.
Configuring socket options such as broadcast and reuse.
Retrieving peer and socket names.

⚠️ This interface is specific to WASI-based WebAssembly and is not supported for JavaScript or non-WASI WebAssembly environments.

Patch 2: classlib: Implement java.net.Socket

This patch introduces the implementation of the java.net.Socket class, enabling developers to work with sockets in a WASI-based environment. Additionally, the following related networking classes are implemented:

java.net.ServerSocket
java.net.InetAddress
java.net.Inet4Address
java.net.Inet6Address
java.net.SocketAddress
java.net.InetSocketAddress
java.net.Proxy
java.net.NetworkInterface
java.net.SocketException
java.net.UnknownHostException

konsoletyper · 2025-01-23T17:20:44Z

First of all, did you get any code from OpenJDK?

konsoletyper · 2025-01-23T17:26:15Z

I have some ideas how to test actual sockets. However, something is missing in current test framework, so I won't force you to write tests for Socket

mandesero · 2025-01-23T17:40:29Z

First of all, did you get any code from OpenJDK?

I reviewed the OpenJDK sources, and only small classes that do not require specific logic, such as SocketAddress, SocketException, and UnknownHostException, may coincide. All other code was written entirely by me.

konsoletyper · 2025-01-23T17:42:08Z

You could have gotten sources from Harmony project

konsoletyper · 2025-01-23T17:46:33Z

How to test this PR? I tried both wasmer and wasmtime and they both complain about missing wasi_snapshot_preview1::sock_open import. Do you know any runtime that supports this?

konsoletyper · 2025-01-23T17:50:56Z

I don't like the idea that non-WASI users are now able to compile code that contains references to sockets, and then suddenly get an error at run time about missing socket support. However, rather than explaining how to do that, I create a patch that will report compile-time error for non-WASI targets if they use sockets:

Subject: [PATCH] socks not supported on non-WASI targets
---
Index: core/src/main/java/org/teavm/runtime/net/VirtualSocketProvider.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/core/src/main/java/org/teavm/runtime/net/VirtualSocketProvider.java b/core/src/main/java/org/teavm/runtime/net/VirtualSocketProvider.java
--- a/core/src/main/java/org/teavm/runtime/net/VirtualSocketProvider.java	(revision 1e702fee24a1f60d8cfd651ac7b22c12b1df9a16)
+++ b/core/src/main/java/org/teavm/runtime/net/VirtualSocketProvider.java	(date 1737654461080)
@@ -15,6 +15,9 @@
  */
 package org.teavm.runtime.net;
 
+import org.teavm.interop.Platforms;
+import org.teavm.interop.SupportedOn;
+
 public final class VirtualSocketProvider {
     private static VirtualSocket instance;
 
@@ -28,6 +31,7 @@
         return instance;
     }
 
+    @SupportedOn(Platforms.WEBASSEMBLY_WASI)
     private static VirtualSocket create() {
         return new VirtualSocketImpl();
     }
Index: core/src/main/java/org/teavm/backend/wasm/WasmTarget.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java b/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java
--- a/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java	(revision 1e702fee24a1f60d8cfd651ac7b22c12b1df9a16)
+++ b/core/src/main/java/org/teavm/backend/wasm/WasmTarget.java	(date 1737653546345)
@@ -1083,7 +1083,11 @@
 
     @Override
     public String[] getPlatformTags() {
-        return new String[] { Platforms.WEBASSEMBLY, Platforms.LOW_LEVEL };
+        return new String[] {
+                Platforms.WEBASSEMBLY,
+                runtimeType == WasmRuntimeType.TEAVM ? Platforms.WEBASSEMBLY_BROWSER : Platforms.WEBASSEMBLY_WASI,
+                Platforms.LOW_LEVEL
+        };
     }
 
     @Override
Index: interop/core/src/main/java/org/teavm/interop/Platforms.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/interop/core/src/main/java/org/teavm/interop/Platforms.java b/interop/core/src/main/java/org/teavm/interop/Platforms.java
--- a/interop/core/src/main/java/org/teavm/interop/Platforms.java	(revision 1e702fee24a1f60d8cfd651ac7b22c12b1df9a16)
+++ b/interop/core/src/main/java/org/teavm/interop/Platforms.java	(date 1737653546357)
@@ -21,6 +21,8 @@
 
     public static final String JAVASCRIPT = "javascript";
     public static final String WEBASSEMBLY = "webassembly";
+    public static final String WEBASSEMBLY_BROWSER = "webassembly-browser";
+    public static final String WEBASSEMBLY_WASI = "webassembly-wasi";
     public static final String C = "c";
     public static final String LOW_LEVEL = "low_level";
     public static final String WEBASSEMBLY_GC = "webassembly-gc";

konsoletyper · 2025-01-23T17:22:36Z

tests/src/test/java/org/teavm/classlib/java/net/InetAddressTest.java

+public class InetAddressTest {
+
+    @Test
+    public void test_LocalhostInet4Address() throws Exception {


Where did you get these tests? I checked Harmony, and they are different. Btw, if you wrote them manually, you could have omitted these obsolete test prefixes

konsoletyper · 2025-01-23T17:23:51Z

tests/src/test/java/org/teavm/classlib/java/net/InetAddressTest.java

+    public void test_LocalhostInet4Address() throws Exception {
+        InetAddress addr1 = InetAddress.getByName("localhost");
+        assertTrue("1. should be an instance of Inet4Address", addr1 instanceof Inet4Address);
+        assertTrue("2. host address should be 127.0.0.1", addr1.getHostAddress().equals("127.0.0.1"));


In case you wrote these tests manually: you could have used assertEquals

BTW, IDEA fixes the whole file in one click

konsoletyper · 2025-01-23T17:24:49Z

tests/src/test/java/org/teavm/classlib/java/net/InetAddressTest.java

+
+    @Test
+    public void test_LocalhostInet4Address() throws Exception {
+        InetAddress addr1 = InetAddress.getByName("localhost");


BTW, it's ok to write var addr1

konsoletyper · 2025-01-23T17:28:56Z

core/src/main/java/org/teavm/runtime/net/VirtualSocketImpl.java

+
+import java.net.SocketException;
+
+public class VirtualSocketImpl implements VirtualSocket {


I think this is excessive. You can just throw UnsupportedOperationException from default implementation of VirtualSocketProvider.

konsoletyper · 2025-01-23T17:54:20Z

core/src/main/java/org/teavm/backend/wasm/runtime/net/impl/AddrInfoHints.java

+
+    @Override
+    public String toString() {
+        return String.format(


I'd avoid String.format. It's hard to implement it efficiently in AOT, but here string concatenation does not look that bad

konsoletyper · 2025-01-23T17:55:33Z

core/src/main/java/org/teavm/backend/wasm/runtime/net/impl/AddrInfo.java

+        return sockType;
+    }
+
+    public Address getAddress() {


I did not see any usages of this method. What is the purpose of the whole class?

konsoletyper · 2025-01-23T18:08:49Z

core/src/main/java/org/teavm/backend/wasm/runtime/net/WasiVirtualSocket.java

+        byte[] addr = new byte[ADDR_SIZE];
+        Address rawAddr = Address.ofData(addr);
+
+        ByteBuffer buffer = ByteBuffer.allocate(BUFFER_SIZE);


You could use structures for this purpose. First of all, instead of BUFFER_SIZE, you can use Structure.sizeOf, and you don't need buffers

BTW, for passing small structures you can use WasiBuffer.getBuffer()

I've rewritten the classes to use structures as recommended.

konsoletyper · 2025-01-23T18:14:27Z

classlib/src/main/java/org/teavm/classlib/java/net/TSocket.java

+            private final byte[] buffer = new byte[MAX_LENGTH];
+
+            @Override
+            public int read() throws IOException {


it would be also good to implement available method

konsoletyper · 2025-01-23T18:16:08Z

core/src/main/java/org/teavm/backend/wasm/runtime/net/impl/SockAddrInet6.java

+        if (!addrPort.contains("[") || !addrPort.contains("]")) {
+            throw new IllegalArgumentException("Invalid format. Expected format: '[ipv6]:port'.");
+        }
+        String[] parts = addrPort.split("]:\");");


It is a syntax error?

This code has been removed, so it is no longer relevant.

konsoletyper · 2025-01-23T18:16:23Z

core/src/main/java/org/teavm/backend/wasm/runtime/net/impl/SockAddrInet6.java

+    }
+
+    private static short[] parseIPv6(String ip) {
+        String[] segments = ip.split(":");


Please, don't use String.split!

I’ve removed these methods for parsing string representations of addresses in SockAddrInet4/6 since they are not used.

mandesero · 2025-01-30T22:18:12Z

How to test this PR? I tried both wasmer and wasmtime and they both complain about missing wasi_snapshot_preview1::sock_open import. Do you know any runtime that supports this?

Sorry for the long delay. You should use WAMR (WebAssembly Micro Runtime), which provides support for WASI socket APIs. You can run your .wasm file using iwasm

Building `iwasm` with WASI socket support

Ensure you have all dependencies installed before proceeding (see).

cd product-mini/platforms/linux
mkdir build && cd build

# Configure the build with necessary features
cmake .. \
  -DWAMR_BUILD_PLATFORM=linux \
  -DWAMR_BUILD_TARGET=X86_64 \
  -DWAMR_BUILD_INTERP=1 \
  -DWAMR_BUILD_FAST_INTERP=1 \
  -DWAMR_BUILD_AOT=1 \
  -DWAMR_BUILD_LIBC_BUILTIN=1 \
  -DWAMR_BUILD_LIBC_WASI=1 \
  -DWAMR_BUILD_THREAD_MGR=1 \
  -DWAMR_BUILD_SHARED_MEMORY=1 \
  -DWAMR_BUILD_SIMD=1

make
# The 'iwasm' binary will be generated in the current directory

Running your WASM file with `iwasm`

Once built, you can execute your .wasm module using iwasm:

./iwasm --addr-pool=0.0.0.0/0 --allow-resolve="*" YourWasmFile.wasm

I will respond to the remaining comments shortly.

This patch provides core socket operations such as creating, binding, connecting, listening, sending, and receiving data, configuring socket options (broadcast and reuse) and retrieving peer and socket names. This interface is specific to the WASI Wasm and is not supported for JS or non-WASI Wasm.

This patch introduces the implementation of the java.net.Socket class, providing functionality for creating, connecting, and managing sockets in a WASI-based environment. Additionally, it includes the implementation of several related networking classes: - java.net.ServerSocket - java.net.InetAddress - java.net.Inet4Address - java.net.Inet6Address - java.net.SocketAddress - java.net.InetSocketAddress - java.net.Proxy - java.net.NetworkInterface - java.net.SocketException - java.net.UnknownHostException

konsoletyper · 2025-02-06T13:44:03Z

When you make fixes in PR, please, don't force-push rebased commit. Instead, you should make commits that fix original commits. When I merge your changes, I'll rebase myself. Otherwise it's extremely hard to track what has changed!

mandesero · 2025-02-06T13:48:13Z

When you make fixes in PR, please, don't force-push rebased commit. Instead, you should make commits that fix original commits. When I merge your changes, I'll rebase myself. Otherwise it's extremely hard to track what has changed!

Sorry, I'll make sure to follow this approach next time.

konsoletyper · 2025-02-07T09:03:30Z

core/src/main/java/org/teavm/backend/wasm/runtime/net/impl/AddrInfo.java

+import org.teavm.interop.Address;
+import org.teavm.interop.Structure;
+
+public class AddrInfo {


I still don't understand the purpose of this class. Why don't you just expose AddrInfoStruct directly, without any wrappers?

I reviewed it again and realized that we can completely remove AddrInfo, which would simplify the code. I also simplified the AddrInfoHints class into a struct and moved it directly into WasiVirtualSocket since it's not used anywhere else.

Simplification of `AddrInfo` and `AddrInfoHints` from classes to structures.

konsoletyper self-requested a review January 23, 2025 17:25

konsoletyper requested changes Jan 23, 2025

View reviewed changes

mandesero added 2 commits February 6, 2025 13:38

mandesero force-pushed the wasi-networking branch from 1e702fe to cf13ca1 Compare February 6, 2025 13:38

konsoletyper reviewed Feb 7, 2025

View reviewed changes

[Patch 1/2] Refactoring

b132783

Simplification of `AddrInfo` and `AddrInfoHints` from classes to structures.

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WASI VirtualSocket interface and Java networking classes implementation #998

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		import java.net.SocketException;

		public class VirtualSocketImpl implements VirtualSocket {

WASI VirtualSocket interface and Java networking classes implementation #998

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WASI VirtualSocket interface and Java networking classes implementation #998

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mandesero commented Jan 20, 2025

Patch 1: WASI: VirtualSocket Interface

Patch 2: classlib: Implement java.net.Socket

konsoletyper commented Jan 23, 2025

konsoletyper commented Jan 23, 2025

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mandesero commented Jan 30, 2025 • edited Loading

Building iwasm with WASI socket support

Running your WASM file with iwasm

konsoletyper commented Feb 6, 2025

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mandesero commented Jan 30, 2025 •

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Building `iwasm` with WASI socket support

Running your WASM file with `iwasm`