rewrite tapserver interface for better error handling

6 files changed, 223 insertions, 57 deletions

diff --git a/Source/Core/Common/SocketContext.cpp b/Source/Core/Common/SocketContext.cpp
index defc333c11..15f9fd9010 100644
--- a/Source/Core/Common/SocketContext.cpp
+++ b/Source/Core/Common/SocketContext.cpp
@@ -8,12 +8,27 @@ namespace Common
 #ifdef _WIN32
 SocketContext::SocketContext()
 {
-  static_cast<void>(WSAStartup(MAKEWORD(2, 2), &m_data));
+  std::lock_guard<std::mutex> g(s_lock);
+  if (s_num_objects == 0)
+  {
+    static_cast<void>(WSAStartup(MAKEWORD(2, 2), &s_data));
+  }
+  s_num_objects++;
 }
 SocketContext::~SocketContext()
 {
-  WSACleanup();
+  std::lock_guard<std::mutex> g(s_lock);
+  s_num_objects--;
+  if (s_num_objects == 0)
+  {
+    WSACleanup();
+  }
 }
+
+std::mutex SocketContext::s_lock;
+size_t SocketContext::s_num_objects = 0;
+WSADATA SocketContext::s_data;
+
 #else
 SocketContext::SocketContext() = default;
 SocketContext::~SocketContext() = default;
diff --git a/Source/Core/Common/SocketContext.h b/Source/Core/Common/SocketContext.h
index 7e072fd8c0..0aa4929e89 100644
--- a/Source/Core/Common/SocketContext.h
+++ b/Source/Core/Common/SocketContext.h
@@ -5,6 +5,7 @@
 
 #ifdef _WIN32
 #include <WinSock2.h>
+#include <mutex>
 #endif
 
 namespace Common
@@ -23,7 +24,9 @@ public:
 
 private:
 #ifdef _WIN32
-  WSADATA m_data;
+  static std::mutex s_lock;
+  static size_t s_num_objects;
+  static WSADATA s_data;
 #endif
 };
 }  // namespace Common
diff --git a/Source/Core/Core/CMakeLists.txt b/Source/Core/Core/CMakeLists.txt
index 945c57760d..10b60a1a1c 100644
--- a/Source/Core/Core/CMakeLists.txt
+++ b/Source/Core/Core/CMakeLists.txt
@@ -189,6 +189,10 @@ add_library(core
   HW/DVD/DVDThread.h
   HW/DVD/FileMonitor.cpp
   HW/DVD/FileMonitor.h
+  HW/EXI/BBA/TAPServer.cpp
+  HW/EXI/BBA/XLINK_KAI_BBA.cpp
+  HW/EXI/BBA/BuiltIn.cpp
+  HW/EXI/BBA/BuiltIn.h
   HW/EXI/EXI_Channel.cpp
   HW/EXI/EXI_Channel.h
   HW/EXI/EXI_Device.cpp
@@ -696,10 +700,6 @@ if(WIN32)
   target_sources(core PRIVATE
     HW/EXI/BBA/TAP_Win32.cpp
     HW/EXI/BBA/TAP_Win32.h
-    HW/EXI/BBA/TAPServer.cpp
-    HW/EXI/BBA/XLINK_KAI_BBA.cpp
-    HW/EXI/BBA/BuiltIn.cpp
-    HW/EXI/BBA/BuiltIn.h
     HW/WiimoteReal/IOWin.cpp
     HW/WiimoteReal/IOWin.h
   )
@@ -713,19 +713,11 @@ if(WIN32)
 elseif(APPLE)
   target_sources(core PRIVATE
     HW/EXI/BBA/TAP_Apple.cpp
-    HW/EXI/BBA/TAPServer.cpp
-    HW/EXI/BBA/XLINK_KAI_BBA.cpp
-    HW/EXI/BBA/BuiltIn.cpp
-    HW/EXI/BBA/BuiltIn.h
   )
   target_link_libraries(core PUBLIC ${IOB_LIBRARY})
 elseif(UNIX)
   target_sources(core PRIVATE
     HW/EXI/BBA/TAP_Unix.cpp
-    HW/EXI/BBA/TAPServer.cpp
-    HW/EXI/BBA/XLINK_KAI_BBA.cpp
-    HW/EXI/BBA/BuiltIn.cpp
-    HW/EXI/BBA/BuiltIn.h
   )
   if(ANDROID)
     target_sources(core PRIVATE
diff --git a/Source/Core/Core/HW/EXI/BBA/TAPServer.cpp b/Source/Core/Core/HW/EXI/BBA/TAPServer.cpp
index 3e0644a41b..f81c1f479f 100644
--- a/Source/Core/Core/HW/EXI/BBA/TAPServer.cpp
+++ b/Source/Core/Core/HW/EXI/BBA/TAPServer.cpp
@@ -22,23 +22,38 @@
 namespace ExpansionInterface
 {
 
+#ifdef _WIN32
+static constexpr auto pi_close = &closesocket;
+using ws_ssize_t = int;
+#else
+static constexpr auto pi_close = &close;
+using ws_ssize_t = ssize_t;
+#endif
+
+#ifdef __LINUX__
+#define SEND_FLAGS MSG_NOSIGNAL
+#else
+#define SEND_FLAGS 0
+#endif
+
 static int ConnectToDestination(const std::string& destination)
 {
   if (destination.empty())
   {
-    INFO_LOG_FMT(SP1, "Cannot connect: destination is empty\n");
+    ERROR_LOG_FMT(SP1, "Cannot connect: destination is empty\n");
     return -1;
   }
 
-  size_t ss_size;
+  int ss_size;
   struct sockaddr_storage ss;
   memset(&ss, 0, sizeof(ss));
   if (destination[0] != '/')
-  {  // IP address or hostname
+  {
+    // IP address or hostname
     size_t colon_offset = destination.find(':');
     if (colon_offset == std::string::npos)
     {
-      INFO_LOG_FMT(SP1, "Destination IP address does not include port\n");
+      ERROR_LOG_FMT(SP1, "Destination IP address does not include port\n");
       return -1;
     }
 
@@ -50,11 +65,12 @@ static int ConnectToDestination(const std::string& destination)
 #ifndef _WIN32
   }
   else
-  {  // UNIX socket
+  {
+    // UNIX socket
     struct sockaddr_un* sun = reinterpret_cast<struct sockaddr_un*>(&ss);
     if (destination.size() + 1 > sizeof(sun->sun_path))
     {
-      INFO_LOG_FMT(SP1, "Socket path is too long, unable to init BBA\n");
+      ERROR_LOG_FMT(SP1, "Socket path is too long, unable to init BBA\n");
       return -1;
     }
     sun->sun_family = AF_UNIX;
@@ -64,7 +80,7 @@ static int ConnectToDestination(const std::string& destination)
   }
   else
   {
-    INFO_LOG_FMT(SP1, "UNIX sockets are not supported on Windows\n");
+    ERROR_LOG_FMT(SP1, "UNIX sockets are not supported on Windows\n");
     return -1;
 #endif
   }
@@ -72,7 +88,7 @@ static int ConnectToDestination(const std::string& destination)
   int fd = socket(ss.ss_family, SOCK_STREAM, (ss.ss_family == AF_INET) ? IPPROTO_TCP : 0);
   if (fd == -1)
   {
-    INFO_LOG_FMT(SP1, "Couldn't create socket; unable to init BBA\n");
+    ERROR_LOG_FMT(SP1, "Couldn't create socket; unable to init BBA\n");
     return -1;
   }
 
@@ -86,7 +102,7 @@ static int ConnectToDestination(const std::string& destination)
   {
     std::string s = Common::LastStrerrorString();
     INFO_LOG_FMT(SP1, "Couldn't connect socket ({}), unable to init BBA\n", s.c_str());
-    close(fd);
+    pi_close(fd);
     return -1;
   }
 
@@ -98,12 +114,44 @@ bool CEXIETHERNET::TAPServerNetworkInterface::Activate()
   if (IsActivated())
     return true;
 
-  fd = ConnectToDestination(m_destination);
+  m_fd = ConnectToDestination(m_destination);
 
   INFO_LOG_FMT(SP1, "BBA initialized.");
   return RecvInit();
 }
 
+void CEXIETHERNET::TAPServerNetworkInterface::Deactivate()
+{
+  pi_close(m_fd);
+  m_fd = -1;
+
+  m_read_enabled.Clear();
+  m_read_shutdown.Set();
+  if (m_read_thread.joinable())
+    m_read_thread.join();
+}
+
+bool CEXIETHERNET::TAPServerNetworkInterface::IsActivated()
+{
+  return (m_fd >= 0);
+}
+
+bool CEXIETHERNET::TAPServerNetworkInterface::RecvInit()
+{
+  m_read_thread = std::thread(&CEXIETHERNET::TAPServerNetworkInterface::ReadThreadHandler, this);
+  return true;
+}
+
+void CEXIETHERNET::TAPServerNetworkInterface::RecvStart()
+{
+  m_read_enabled.Set();
+}
+
+void CEXIETHERNET::TAPServerNetworkInterface::RecvStop()
+{
+  m_read_enabled.Clear();
+}
+
 bool CEXIETHERNET::TAPServerNetworkInterface::SendFrame(const u8* frame, u32 size)
 {
   {
@@ -111,13 +159,16 @@ bool CEXIETHERNET::TAPServerNetworkInterface::SendFrame(const u8* frame, u32 siz
     INFO_LOG_FMT(SP1, "SendFrame {}\n{}", size, s);
   }
 
-  auto size16 = u16(size);
-  if (write(fd, &size16, 2) != 2)
+  // On Windows, the data pointer is of type const char*; on other systems it is
+  // of type const void*. This is the reason for the reinterpret_cast here and
+  // in the other send/recv calls in this file.
+  u8 size_bytes[2] = {static_cast<u8>(size), static_cast<u8>(size >> 8)};
+  if (send(m_fd, reinterpret_cast<const char*>(size_bytes), 2, SEND_FLAGS) != 2)
   {
     ERROR_LOG_FMT(SP1, "SendFrame(): could not write size field");
     return false;
   }
-  int written_bytes = write(fd, frame, size);
+  int written_bytes = send(m_fd, reinterpret_cast<const char*>(frame), size, SEND_FLAGS);
   if (u32(written_bytes) != size)
   {
     ERROR_LOG_FMT(SP1, "SendFrame(): expected to write {} bytes, instead wrote {}", size,
@@ -133,45 +184,122 @@ bool CEXIETHERNET::TAPServerNetworkInterface::SendFrame(const u8* frame, u32 siz
 
 void CEXIETHERNET::TAPServerNetworkInterface::ReadThreadHandler()
 {
-  while (!readThreadShutdown.IsSet())
+  while (!m_read_shutdown.IsSet())
   {
     fd_set rfds;
     FD_ZERO(&rfds);
-    FD_SET(fd, &rfds);
+    FD_SET(m_fd, &rfds);
 
     timeval timeout;
     timeout.tv_sec = 0;
     timeout.tv_usec = 50000;
-    if (select(fd + 1, &rfds, nullptr, nullptr, &timeout) <= 0)
+    if (select(m_fd + 1, &rfds, nullptr, nullptr, &timeout) <= 0)
       continue;
 
-    u16 size;
-    if (read(fd, &size, 2) != 2)
+    // The tapserver protocol is very simple: there is a 16-bit little-endian
+    // size field, followed by that many bytes of packet data
+    switch (m_read_state)
+    {
+    case ReadState::Size:
+    {
+      u8 size_bytes[2];
+      ws_ssize_t bytes_read = recv(m_fd, reinterpret_cast<char*>(size_bytes), 2, 0);
+      if (bytes_read == 1)
+      {
+        m_read_state = ReadState::SizeHigh;
+        m_read_packet_bytes_remaining = size_bytes[0];
+      }
+      else if (bytes_read == 2)
+      {
+        m_read_packet_bytes_remaining = size_bytes[0] | (size_bytes[1] << 8);
+        if (m_read_packet_bytes_remaining > BBA_RECV_SIZE)
+        {
+          ERROR_LOG_FMT(SP1, "Packet is too large ({} bytes); dropping it",
+                        m_read_packet_bytes_remaining);
+          m_read_state = ReadState::Skip;
+        }
+        else
+        {
+          m_read_state = ReadState::Data;
+        }
+      }
+      else
+      {
+        ERROR_LOG_FMT(SP1, "Failed to read size field from BBA: {}", Common::LastStrerrorString());
+      }
+      break;
+    }
+    case ReadState::SizeHigh:
+    {
+      // This handles the annoying case where only one byte of the size field
+      // was available earlier.
+      u8 size_high = 0;
+      ws_ssize_t bytes_read = recv(m_fd, reinterpret_cast<char*>(&size_high), 1, 0);
+      if (bytes_read == 1)
+      {
+        m_read_packet_bytes_remaining |= (size_high << 8);
+        if (m_read_packet_bytes_remaining > BBA_RECV_SIZE)
+        {
+          ERROR_LOG_FMT(SP1, "Packet is too large ({} bytes); dropping it",
+                        m_read_packet_bytes_remaining);
+          m_read_state = ReadState::Skip;
+        }
+        else
+        {
+          m_read_state = ReadState::Data;
+        }
+      }
+      else
+      {
+        ERROR_LOG_FMT(SP1, "Failed to read split size field from BBA: {}",
+                      Common::LastStrerrorString());
+      }
+      break;
+    }
+    case ReadState::Data:
     {
-      ERROR_LOG_FMT(SP1, "Failed to read size field from BBA: {}", Common::LastStrerrorString());
+      ws_ssize_t bytes_read =
+          recv(m_fd, reinterpret_cast<char*>(m_eth_ref->mRecvBuffer.get() + m_read_packet_offset),
+               m_read_packet_bytes_remaining, 0);
+      if (bytes_read <= 0)
+      {
+        ERROR_LOG_FMT(SP1, "Failed to read data from BBA: {}", Common::LastStrerrorString());
+      }
+      else
+      {
+        m_read_packet_offset += bytes_read;
+        m_read_packet_bytes_remaining -= bytes_read;
+        if (m_read_packet_bytes_remaining == 0)
+        {
+          m_eth_ref->mRecvBufferLength = m_read_packet_offset;
+          m_eth_ref->RecvHandlePacket();
+          m_read_state = ReadState::Size;
+          m_read_packet_offset = 0;
+        }
+      }
+      break;
     }
-    else
+    case ReadState::Skip:
     {
-      int read_bytes = read(fd, m_eth_ref->mRecvBuffer.get(), size);
-      if (read_bytes < 0)
+      ws_ssize_t bytes_read = recv(m_fd, reinterpret_cast<char*>(m_eth_ref->mRecvBuffer.get()),
+                                   std::min<int>(m_read_packet_bytes_remaining, BBA_RECV_SIZE), 0);
+      if (bytes_read <= 0)
       {
-        ERROR_LOG_FMT(SP1, "Failed to read packet data from BBA: {}", Common::LastStrerrorString());
+        ERROR_LOG_FMT(SP1, "Failed to read data from BBA: {}", Common::LastStrerrorString());
       }
-      else if (readEnabled.IsSet())
+      else
       {
-        std::string data_string = ArrayToString(m_eth_ref->mRecvBuffer.get(), read_bytes, 0x10);
-        INFO_LOG_FMT(SP1, "Read data: {}", data_string);
-        m_eth_ref->mRecvBufferLength = read_bytes;
-        m_eth_ref->RecvHandlePacket();
+        m_read_packet_bytes_remaining -= bytes_read;
+        if (m_read_packet_bytes_remaining == 0)
+        {
+          m_read_state = ReadState::Size;
+          m_read_packet_offset = 0;
+        }
       }
+      break;
+    }
     }
   }
 }
 
-bool CEXIETHERNET::TAPServerNetworkInterface::RecvInit()
-{
-  readThread = std::thread(&CEXIETHERNET::TAPServerNetworkInterface::ReadThreadHandler, this);
-  return true;
-}
-
 }  // namespace ExpansionInterface
diff --git a/Source/Core/Core/HW/EXI/EXI_DeviceEthernet.h b/Source/Core/Core/HW/EXI/EXI_DeviceEthernet.h
index 301420fbea..067f5d59c0 100644
--- a/Source/Core/Core/HW/EXI/EXI_DeviceEthernet.h
+++ b/Source/Core/Core/HW/EXI/EXI_DeviceEthernet.h
@@ -17,6 +17,7 @@
 
 #include "Common/Flag.h"
 #include "Common/Network.h"
+#include "Common/SocketContext.h"
 #include "Core/HW/EXI/BBA/BuiltIn.h"
 #include "Core/HW/EXI/EXI_Device.h"
 
@@ -362,21 +363,42 @@ private:
 #endif
   };
 
-  class TAPServerNetworkInterface : public TAPNetworkInterface
+  class TAPServerNetworkInterface : public NetworkInterface
   {
   public:
     explicit TAPServerNetworkInterface(CEXIETHERNET* eth_ref, const std::string& destination)
-        : TAPNetworkInterface(eth_ref), m_destination(destination)
+        : NetworkInterface(eth_ref), m_destination(destination)
     {
     }
 
   public:
     bool Activate() override;
+    void Deactivate() override;
+    bool IsActivated() override;
     bool SendFrame(const u8* frame, u32 size) override;
     bool RecvInit() override;
+    void RecvStart() override;
+    void RecvStop() override;
 
   private:
+    enum class ReadState
+    {
+      Size,
+      SizeHigh,
+      Data,
+      Skip,
+    };
+
     std::string m_destination;
+    Common::SocketContext m_socket_context;
+
+    int m_fd = -1;
+    ReadState m_read_state = ReadState::Size;
+    u16 m_read_packet_offset;
+    u16 m_read_packet_bytes_remaining;
+    std::thread m_read_thread;
+    Common::Flag m_read_enabled;
+    Common::Flag m_read_shutdown;
 
     void ReadThreadHandler();
   };
diff --git a/Source/Core/DolphinQt/Settings/BroadbandAdapterSettingsDialog.cpp b/Source/Core/DolphinQt/Settings/BroadbandAdapterSettingsDialog.cpp
index f8abbc77ab..9716d8f211 100644
--- a/Source/Core/DolphinQt/Settings/BroadbandAdapterSettingsDialog.cpp
+++ b/Source/Core/DolphinQt/Settings/BroadbandAdapterSettingsDialog.cpp
@@ -49,13 +49,19 @@ void BroadbandAdapterSettingsDialog::InitControls()
     break;
 
   case Type::TapServer:
-    address_label = new QLabel(tr("UNIX socket path or netloc (address:port):"));
-    address_placeholder = QStringLiteral("/tmp/dolphin-tap");
     current_address = QString::fromStdString(Config::Get(Config::MAIN_BBA_TAPSERVER_DESTINATION));
-    description =
-        new QLabel(tr("On macOS and Linux, the default value \"/tmp/dolphin-tap\" will work with "
-                      "tapserver and newserv. On Windows, you must enter an IP address and port."));
-
+#ifdef _WIN32
+    address_label = new QLabel(tr("Destination (address:port):"));
+    address_placeholder = QStringLiteral("");
+    description = new QLabel(
+        tr("Enter the IP address and port of the tapserver instance you want to connect to."));
+#else
+    address_label = new QLabel(tr("Destination (UNIX socket path or address:port):"));
+    address_placeholder = QStringLiteral("/tmp/dolphin-tap");
+    description = new QLabel(tr(
+        "The default value \"/tmp/dolphin-tap\" will work with a local tapserver and newserv. You "
+        "can also enter a network location (address:port) to connect to a remote tapserver."));
+#endif
     window_title = tr("BBA destination address");
     break;