Add basic TCP socket mojo implementation

mojo/examples/http_server/http_server.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdio.h>
+#include <arpa/inet.h>
 
 #include "base/bind.h"
+#include "base/memory/weak_ptr.h"
+#include "mojo/common/handle_watcher.h"
 #include "mojo/public/c/system/main.h"
 #include "mojo/public/cpp/application/application_delegate.h"
 #include "mojo/public/cpp/application/application_impl.h"
 #include "mojo/public/cpp/application/application_runner.h"
+#include "mojo/public/cpp/system/data_pipe.h"
 #include "mojo/services/public/interfaces/network/network_service.mojom.h"
 
 namespace mojo {
 namespace examples {
 
+// The canned response that this server replies to each request with.
+const char kResponse[] =
+    "HTTP/1.0 200 OK\n"
+    "Content-Type: text/html; charset=utf-8\n"
+    "\n"
+    "Hello, world\n";
+
+// Represents one connection to a client. This connection will manage its own
+// lifetime and will delete itself when the connection is closed.
+class Connection {
+ public:
+  Connection(TCPConnectedSocketPtr conn,
+             ScopedDataPipeProducerHandle sender,
+             ScopedDataPipeConsumerHandle receiver)
+      : connection_(conn.Pass()),
+        sender_(sender.Pass()),
+        receiver_(receiver.Pass()),
+        weak_ptr_factory_(this),
+        response_(kResponse),
+        response_offset_(0) {
+    WriteMore();
+  }
+
+  ~Connection() {
+  }
+
+ private:
+  void OnSenderReady(MojoResult result) {
+    WriteMore();
+  }
+
+  void WriteMore() {
+    uint32_t num_bytes =
+        static_cast<uint32_t>(response_.size() - response_offset_);
+    // TODO(brettw) write chunks (ideally capped at some small size to
+    // illustrate how it works even in the presence of our relatively small
+    // reply) rather than specifying ALL_OR_NONE. See below.
+    MojoResult result = WriteDataRaw(
+        sender_.get(), &response_[response_offset_], &num_bytes,
+        MOJO_WRITE_DATA_FLAG_ALL_OR_NONE);
+    if (result == MOJO_RESULT_SHOULD_WAIT) {
+      num_bytes = 0;
+    } else if (result != MOJO_RESULT_OK) {
+      printf("Error writing to pipe.\n");
+      delete this;
+      return;
+    }
+
+    response_offset_ += num_bytes;
+
+    if (response_offset_ == response_.size()) {
+      // Connection complete.
+      delete this;
+      return;
+    }
+
+    // Wait for sender to be writable.
+    // TODO(brettw) we won't actually get here since we ALL_OR_NONE was
+    // specified above. This call won't work because the message loop is not a
+    // Chromium message loop. Instead, we probably need to use
+    // Environment::GetDefaultAsyncWaiter to wait on the handles and remove the
+    // ALL_OR_NONE flag.
+    sender_watcher_.Start(
+        sender_.get(),
+        MOJO_HANDLE_SIGNAL_WRITABLE, MOJO_DEADLINE_INDEFINITE,
+        base::Bind(&Connection::OnSenderReady, weak_ptr_factory_.GetWeakPtr()));
+  }
+
+  TCPConnectedSocketPtr connection_;
+  ScopedDataPipeProducerHandle sender_;
+  ScopedDataPipeConsumerHandle receiver_;
+
+  base::WeakPtrFactory<Connection> weak_ptr_factory_;
+  common::HandleWatcher sender_watcher_;
+
+  std::string response_;
+  size_t response_offset_;
+};
+
 class HttpServerApp : public ApplicationDelegate {
  public:
   virtual void Initialize(ApplicationImpl* app) override {
     app->ConnectToService("mojo:mojo_network_service", &network_service_);
     Start();
   }
 
  private:
-  void OnListeningStarted(NetworkErrorPtr err) {
-  }
-
   void OnSocketBound(NetworkErrorPtr err, NetAddressPtr bound_address) {
     if (err->code != 0) {
       printf("Bound err = %d\n", err->code);
       return;
     }
 
-    printf("Got address = %d.%d.%d.%d:%d\n",
+    printf("Got address %d.%d.%d.%d:%d\n",
            (int)bound_address->ipv4->addr[0],
            (int)bound_address->ipv4->addr[1],
            (int)bound_address->ipv4->addr[2],
            (int)bound_address->ipv4->addr[3],
            (int)bound_address->ipv4->port);
+  }
 
-    bound_socket_->StartListening(
-        GetProxy(&server_socket_),
-        base::Bind(&HttpServerApp::OnListeningStarted,
-                   base::Unretained(this)));
+  void OnSocketListening(NetworkErrorPtr err) {
+    if (err->code != 0) {
+      printf("Listen err = %d\n", err->code);
+      return;
+    }
+    printf("Waiting for incoming connections...\n");
+  }
+
+  void OnConnectionAccepted(NetworkErrorPtr err, NetAddressPtr remote_address) {
+    if (err->code != 0) {
+      printf("Accepted socket error = %d\n", err->code);
+      return;
+    }
+
+    new Connection(pending_connected_socket_.Pass(),
+                   pending_send_handle_.Pass(),
+                   pending_receive_handle_.Pass());
+
+    // Ready for another connection.
+    WaitForNextConnection();
+  }
+
+  void WaitForNextConnection() {
+    // Need two pipes (one for each direction).
+    ScopedDataPipeConsumerHandle send_consumer_handle;
+    MojoResult result = CreateDataPipe(
+        nullptr, &pending_send_handle_, &send_consumer_handle);
+    assert(result == MOJO_RESULT_OK);
+
+    ScopedDataPipeProducerHandle receive_producer_handle;
+    result = CreateDataPipe(
+        nullptr, &receive_producer_handle, &pending_receive_handle_);
+    assert(result == MOJO_RESULT_OK);
+
+    server_socket_->Accept(send_consumer_handle.Pass(),
+                           receive_producer_handle.Pass(),
+                           GetProxy(&pending_connected_socket_),
+                           base::Bind(&HttpServerApp::OnConnectionAccepted,
+                                      base::Unretained(this)));
   }
 
   void Start() {
     NetAddressPtr net_address(NetAddress::New());
     net_address->family = NET_ADDRESS_FAMILY_IPV4;
     net_address->ipv4 = NetAddressIPv4::New();
     net_address->ipv4->addr.resize(4);
-    net_address->ipv4->addr[0] = 0;
+    net_address->ipv4->addr[0] = 127;
     net_address->ipv4->addr[1] = 0;
     net_address->ipv4->addr[2] = 0;
-    net_address->ipv4->addr[3] = 0;
+    net_address->ipv4->addr[3] = 1;
+    net_address->ipv4->port = 0;
 
+    // Note that we can start using the proxies right away even thought the
+    // callbacks have not been called yet. If a previous step fails, they'll
+    // all fail.
     network_service_->CreateTCPBoundSocket(
         net_address.Pass(),
         GetProxy(&bound_socket_),
         base::Bind(&HttpServerApp::OnSocketBound, base::Unretained(this)));
+    bound_socket_->StartListening(GetProxy(
+        &server_socket_),
+        base::Bind(&HttpServerApp::OnSocketListening, base::Unretained(this)));
+    WaitForNextConnection();
   }
 
   NetworkServicePtr network_service_;
   TCPBoundSocketPtr bound_socket_;
   TCPServerSocketPtr server_socket_;
+
+  ScopedDataPipeProducerHandle pending_send_handle_;
+  ScopedDataPipeConsumerHandle pending_receive_handle_;
+  TCPConnectedSocketPtr pending_connected_socket_;
 };
 
 }  // namespace examples
 }  // namespace mojo
 
 MojoResult MojoMain(MojoHandle shell_handle) {
   mojo::ApplicationRunner runner(new mojo::examples::HttpServerApp);
   return runner.Run(shell_handle);
 }