featL: implement proxy foreign call.

src/main/java/io/roastedroot/proxywasm/impl/Imports.java

@@ -862,4 +862,31 @@ int proxyDispatchHttpCall(
             return e.result().getValue();
         }
     }
+
+    @WasmExport
+    int proxyCallForeignFunction(
+            int nameDataPtr,
+            int nameSize,
+            int argumentDataPtr,
+            int argumentSize,
+            int returnResultsPtr,
+            int returnResultsSizePtr) {
+        try {
+            var name = string(readMemory(nameDataPtr, nameSize));
+            var argument = readMemory(argumentDataPtr, argumentSize);
+            var result = handler.callForeignFunction(name, argument);
+
+            // Allocate memory in the WebAssembly instance
+            int addr = malloc(result.length);
+            putMemory(addr, result);
+            // Write the address to the return pointer
+            putUint32(returnResultsPtr, addr);
+            // Write the length to the return size pointer
+            putUint32(returnResultsSizePtr, result.length);
+            return WasmResult.OK.getValue();
+
+        } catch (WasmException e) {
+            return e.result().getValue();
+        }
+    }
 }

src/main/java/io/roastedroot/proxywasm/v1/ChainedHandler.java

@@ -265,4 +265,20 @@ public int httpCall(
             throws WasmException {
         return next().httpCall(uri, headers, body, trailers, timeout);
     }
+
+    @Override
+    public int dispatchHttpCall(
+            String upstreamName,
+            HashMap<String, String> headers,
+            byte[] body,
+            HashMap<String, String> trailers,
+            int timeoutMilliseconds)
+            throws WasmException {
+        return next().dispatchHttpCall(upstreamName, headers, body, trailers, timeoutMilliseconds);
+    }
+
+    @Override
+    public byte[] callForeignFunction(String name, byte[] bytes) throws WasmException {
+        return next().callForeignFunction(name, bytes);
+    }
 }

src/main/java/io/roastedroot/proxywasm/v1/ForeignFunction.java

@@ -0,0 +1,5 @@
+package io.roastedroot.proxywasm.v1;
+
+public interface ForeignFunction {
+    byte[] apply(byte[] data);
+}

src/main/java/io/roastedroot/proxywasm/v1/Handler.java

@@ -406,4 +406,8 @@ default int dispatchHttpCall(
             throws WasmException {
         throw new WasmException(WasmResult.UNIMPLEMENTED);
     }
+
+    default byte[] callForeignFunction(String name, byte[] bytes) throws WasmException {
+        throw new WasmException(WasmResult.NOT_FOUND);
+    }
 }

src/main/java/io/roastedroot/proxywasm/v1/ProxyWasm.java

@@ -43,6 +43,7 @@ public final class ProxyWasm implements Closeable {
     private Map<String, String> httpCallResponseHeaders;
     private Map<String, String> httpCallResponseTrailers;
     private byte[] httpCallResponseBody;
+    private HashMap<String, ForeignFunction> foreignFunctions = new HashMap<>();
 
     private ProxyWasm(Builder other) throws StartException {
         this.vmConfig = other.vmConfig;
@@ -169,6 +170,15 @@ public Map<String, String> getHttpCallResponseTrailers() {
             public byte[] getHttpCallResponseBody() {
                 return httpCallResponseBody;
             }
+
+            @Override
+            public byte[] callForeignFunction(String name, byte[] bytes) throws WasmException {
+                ForeignFunction func = foreignFunctions.get(name);
+                if (func == null) {
+                    throw new WasmException(WasmResult.NOT_FOUND);
+                }
+                return func.apply(bytes);
+            }
         };
     }
 
@@ -266,6 +276,10 @@ public int contextId() {
         return pluginContext.id();
     }
 
+    public void registerForeignFunction(String name, ForeignFunction func) {
+        foreignFunctions.put(name, func);
+    }
+
     public static class Builder implements Cloneable {
 
         private Exports exports;

src/test/go-examples/foreign_call_on_tick/README.md

@@ -0,0 +1,4 @@
+## Attribution
+
+This example originally came from:
+https://github.com/proxy-wasm/proxy-wasm-go-sdk/tree/main/examples/foreign_call_on_tick

src/test/go-examples/foreign_call_on_tick/go.mod

@@ -0,0 +1,5 @@
+module github.com/proxy-wasm/proxy-wasm-go-sdk/examples/foreign_call_on_tick
+
+go 1.24
+
+require github.com/proxy-wasm/proxy-wasm-go-sdk v0.0.0-20250212164326-ab4161dcf924

src/test/go-examples/foreign_call_on_tick/go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/proxy-wasm/proxy-wasm-go-sdk v0.0.0-20250212164326-ab4161dcf924 h1:wTcK6gcyTKJMeDka69AMjZYvisdI8CBXzTEfZ+2pOxI=
+github.com/proxy-wasm/proxy-wasm-go-sdk v0.0.0-20250212164326-ab4161dcf924/go.mod h1:9mBRvh8I6Td6sg3CwEY+zGFE4DKaIoieCaca1kQnDBE=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

src/test/go-examples/foreign_call_on_tick/main.go

@@ -0,0 +1,69 @@
+// Copyright 2020-2024 Tetrate
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"encoding/hex"
+
+	"github.com/proxy-wasm/proxy-wasm-go-sdk/proxywasm"
+	"github.com/proxy-wasm/proxy-wasm-go-sdk/proxywasm/types"
+)
+
+const tickMilliseconds uint32 = 1
+
+func main() {}
+func init() {
+	proxywasm.SetVMContext(&vmContext{})
+}
+
+// vmContext implements types.VMContext.
+type vmContext struct {
+	// Embed the default VM context here,
+	// so that we don't need to reimplement all the methods.
+	types.DefaultVMContext
+}
+
+// NewPluginContext implements types.VMContext.
+func (*vmContext) NewPluginContext(contextID uint32) types.PluginContext {
+	return &pluginContext{}
+}
+
+// pluginContext implements types.PluginContext.
+type pluginContext struct {
+	// Embed the default plugin context here,
+	// so that we don't need to reimplement all the methods.
+	types.DefaultPluginContext
+	callNum uint32
+}
+
+// OnPluginStart implements types.PluginContext.
+func (ctx *pluginContext) OnPluginStart(pluginConfigurationSize int) types.OnPluginStartStatus {
+	if err := proxywasm.SetTickPeriodMilliSeconds(tickMilliseconds); err != nil {
+		proxywasm.LogCriticalf("failed to set tick period: %v", err)
+		return types.OnPluginStartStatusFailed
+	}
+	proxywasm.LogInfof("set tick period milliseconds: %d", tickMilliseconds)
+	return types.OnPluginStartStatusOK
+}
+
+// OnTick implements types.PluginContext.
+func (ctx *pluginContext) OnTick() {
+	ctx.callNum++
+	ret, err := proxywasm.CallForeignFunction("compress", []byte("hello world!"))
+	if err != nil {
+		proxywasm.LogCriticalf("foreign function (compress) failed: %v", err)
+	}
+	proxywasm.LogInfof("foreign function (compress) called: %d, result: %s", ctx.callNum, hex.EncodeToString(ret))
+}

src/test/java/io/roastedroot/proxywasm/ForeignCallOnTickTest.java

@@ -0,0 +1,37 @@
+package io.roastedroot.proxywasm;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.dylibso.chicory.wasm.Parser;
+import io.roastedroot.proxywasm.v1.ProxyWasm;
+import io.roastedroot.proxywasm.v1.StartException;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+
+/**
+ */
+public class ForeignCallOnTickTest {
+
+    static int tickMilliseconds = 1;
+
+    @Test
+    public void testOnTick() throws StartException {
+
+        var handler = new MockHandler();
+        var module = Parser.parse(Path.of("./src/test/go-examples/foreign_call_on_tick/main.wasm"));
+        ProxyWasm.Builder builder = ProxyWasm.builder().withPluginHandler(handler);
+        try (var host = builder.build(module)) {
+            assertEquals(tickMilliseconds, handler.getTickPeriodMilliseconds());
+
+            host.registerForeignFunction("compress", data -> data);
+
+            for (int i = 1; i <= 10; i++) {
+                host.tick(); // call OnTick
+                handler.assertLogsContain(
+                        String.format(
+                                "foreign function (compress) called: %d, result: %s",
+                                i, "68656c6c6f20776f726c6421"));
+            }
+        }
+    }
+}