Add rpc server using service factory

Using the service factory, users can put contexts to binder services.
For example, the server can identify calling clients.

Bug: 199259751
Test: atest MicrodroidHostTestCases ComposHostTestCases
Change-Id: I8ed845e2a8e49a61531e6e4aadc88de7146fe8c0
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 2ecb895..56cf76f 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -331,6 +331,7 @@
         "libbase",
         "libbinder",
         "libbinder_ndk",
+        "liblog",
         "libutils",
     ],
     export_include_dirs: ["include_rpc_unstable"],
diff --git a/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp b/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp
index 08f5eed..34f1cbf 100644
--- a/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp
+++ b/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp
@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include <sys/socket.h>
+
 extern "C" {
 
 struct AIBinder;
@@ -30,6 +32,12 @@
 bool RunRpcServerCallback(AIBinder* service, unsigned int port, void (*readyCallback)(void* param),
                           void* param);
 
+// Starts an RPC server on a given port and a given root IBinder object.
+// This function sets up the server, calls readyCallback with a given param, and
+// then joins before returning.
+bool RunRpcServerWithFactory(AIBinder* (*factory)(unsigned int cid, void* context),
+                          void* factoryContext, unsigned int port);
+
 AIBinder* RpcClient(unsigned int cid, unsigned int port);
 
 // Connect to an RPC server with preconnected file descriptors.
diff --git a/libs/binder/libbinder_rpc_unstable.cpp b/libs/binder/libbinder_rpc_unstable.cpp
index 6dfec75..bf2b25b 100644
--- a/libs/binder/libbinder_rpc_unstable.cpp
+++ b/libs/binder/libbinder_rpc_unstable.cpp
@@ -19,6 +19,7 @@
 #include <android/binder_libbinder.h>
 #include <binder/RpcServer.h>
 #include <binder/RpcSession.h>
+#include <linux/vm_sockets.h>
 
 using android::OK;
 using android::RpcServer;
@@ -29,6 +30,28 @@
 
 extern "C" {
 
+bool RunRpcServerWithFactory(AIBinder* (*factory)(unsigned int cid, void* context),
+                             void* factoryContext, unsigned int port) {
+    auto server = RpcServer::make();
+    if (status_t status = server->setupVsockServer(port); status != OK) {
+        LOG(ERROR) << "Failed to set up vsock server with port " << port
+                   << " error: " << statusToString(status).c_str();
+        return false;
+    }
+    server->setPerSessionRootObject([=](const sockaddr* addr, socklen_t addrlen) {
+        LOG_ALWAYS_FATAL_IF(addr->sa_family != AF_VSOCK, "address is not a vsock");
+        LOG_ALWAYS_FATAL_IF(addrlen < sizeof(sockaddr_vm), "sockaddr is truncated");
+        const sockaddr_vm* vaddr = reinterpret_cast<const sockaddr_vm*>(addr);
+        return AIBinder_toPlatformBinder(factory(vaddr->svm_cid, factoryContext));
+    });
+
+    server->join();
+
+    // Shutdown any open sessions since server failed.
+    (void)server->shutdown();
+    return true;
+}
+
 bool RunRpcServerCallback(AIBinder* service, unsigned int port, void (*readyCallback)(void* param),
                           void* param) {
     auto server = RpcServer::make();