1 files changed, 333 insertions, 0 deletions
diff --git a/Utilities/cmcppdap/src/socket.cpp b/Utilities/cmcppdap/src/socket.cpp
new file mode 100644
index 0000000..1211310
--- /dev/null
+++ b/Utilities/cmcppdap/src/socket.cpp
@@ -0,0 +1,333 @@
+// Copyright 2019 Google LLC
+//
+// 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
+//
+//     https://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.
+
+#include "socket.h"
+
+#include "rwmutex.h"
+
+#if defined(_WIN32)
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <netdb.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#endif
+
+#if defined(_WIN32)
+#include <atomic>
+namespace {
+std::atomic<int> wsaInitCount = {0};
+}  // anonymous namespace
+#else
+#include <fcntl.h>
+#include <unistd.h>
+namespace {
+using SOCKET = int;
+}  // anonymous namespace
+#endif
+
+namespace {
+constexpr SOCKET InvalidSocket = static_cast<SOCKET>(-1);
+void init() {
+#if defined(_WIN32)
+  if (wsaInitCount++ == 0) {
+    WSADATA winsockData;
+    (void)WSAStartup(MAKEWORD(2, 2), &winsockData);
+  }
+#endif
+}
+
+void term() {
+#if defined(_WIN32)
+  if (--wsaInitCount == 0) {
+    WSACleanup();
+  }
+#endif
+}
+
+bool setBlocking(SOCKET s, bool blocking) {
+#if defined(_WIN32)
+  u_long mode = blocking ? 0 : 1;
+  return ioctlsocket(s, FIONBIO, &mode) == NO_ERROR;
+#else
+  auto arg = fcntl(s, F_GETFL, nullptr);
+  if (arg < 0) {
+    return false;
+  }
+  arg = blocking ? (arg & ~O_NONBLOCK) : (arg | O_NONBLOCK);
+  return fcntl(s, F_SETFL, arg) >= 0;
+#endif
+}
+
+bool errored(SOCKET s) {
+  if (s == InvalidSocket) {
+    return true;
+  }
+  char error = 0;
+  socklen_t len = sizeof(error);
+  getsockopt(s, SOL_SOCKET, SO_ERROR, &error, &len);
+  return error != 0;
+}
+
+}  // anonymous namespace
+
+class dap::Socket::Shared : public dap::ReaderWriter {
+ public:
+  static std::shared_ptr<Shared> create(const char* address, const char* port) {
+    init();
+
+    addrinfo hints = {};
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_protocol = IPPROTO_TCP;
+    hints.ai_flags = AI_PASSIVE;
+
+    addrinfo* info = nullptr;
+    getaddrinfo(address, port, &hints, &info);
+
+    if (info) {
+      auto socket =
+          ::socket(info->ai_family, info->ai_socktype, info->ai_protocol);
+      auto out = std::make_shared<Shared>(info, socket);
+      out->setOptions();
+      return out;
+    }
+
+    freeaddrinfo(info);
+    term();
+    return nullptr;
+  }
+
+  Shared(SOCKET socket) : info(nullptr), s(socket) {}
+  Shared(addrinfo* info, SOCKET socket) : info(info), s(socket) {}
+
+  ~Shared() {
+    freeaddrinfo(info);
+    close();
+    term();
+  }
+
+  template <typename FUNCTION>
+  void lock(FUNCTION&& f) {
+    RLock l(mutex);
+    f(s, info);
+  }
+
+  void setOptions() {
+    RLock l(mutex);
+    if (s == InvalidSocket) {
+      return;
+    }
+
+    int enable = 1;
+
+#if !defined(_WIN32)
+    // Prevent sockets lingering after process termination, causing
+    // reconnection issues on the same port.
+    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char*)&enable, sizeof(enable));
+
+    struct {
+      int l_onoff;  /* linger active */
+      int l_linger; /* how many seconds to linger for */
+    } linger = {false, 0};
+    setsockopt(s, SOL_SOCKET, SO_LINGER, (char*)&linger, sizeof(linger));
+#endif  // !defined(_WIN32)
+
+    // Enable TCP_NODELAY.
+    // DAP usually consists of small packet requests, with small packet
+    // responses. When there are many frequent, blocking requests made,
+    // Nagle's algorithm can dramatically limit the request->response rates.
+    setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (char*)&enable, sizeof(enable));
+  }
+
+  // dap::ReaderWriter compliance
+  bool isOpen() {
+    {
+      RLock l(mutex);
+      if ((s != InvalidSocket) && !errored(s)) {
+        return true;
+      }
+    }
+    WLock lock(mutex);
+    s = InvalidSocket;
+    return false;
+  }
+
+  void close() {
+    {
+      RLock l(mutex);
+      if (s != InvalidSocket) {
+#if defined(_WIN32)
+        closesocket(s);
+#elif __APPLE__
+        // ::shutdown() *should* be sufficient to unblock ::accept(), but
+        // apparently on macos it can return ENOTCONN and ::accept() continues
+        // to block indefinitely.
+        // Note: There is a race here. Calling ::close() frees the socket ID,
+        // which may be reused before `s` is assigned InvalidSocket.
+        ::shutdown(s, SHUT_RDWR);
+        ::close(s);
+#else
+        // ::shutdown() to unblock ::accept(). We'll actually close the socket
+        // under lock below.
+        ::shutdown(s, SHUT_RDWR);
+#endif
+      }
+    }
+
+    WLock l(mutex);
+    if (s != InvalidSocket) {
+#if !defined(_WIN32) && !defined(__APPLE__)
+      ::close(s);
+#endif
+      s = InvalidSocket;
+    }
+  }
+
+  size_t read(void* buffer, size_t bytes) {
+    RLock lock(mutex);
+    if (s == InvalidSocket) {
+      return 0;
+    }
+    auto len =
+        recv(s, reinterpret_cast<char*>(buffer), static_cast<int>(bytes), 0);
+    return (len < 0) ? 0 : len;
+  }
+
+  bool write(const void* buffer, size_t bytes) {
+    RLock lock(mutex);
+    if (s == InvalidSocket) {
+      return false;
+    }
+    if (bytes == 0) {
+      return true;
+    }
+    return ::send(s, reinterpret_cast<const char*>(buffer),
+                  static_cast<int>(bytes), 0) > 0;
+  }
+
+ private:
+  addrinfo* const info;
+  SOCKET s = InvalidSocket;
+  RWMutex mutex;
+};
+
+namespace dap {
+
+Socket::Socket(const char* address, const char* port)
+    : shared(Shared::create(address, port)) {
+  if (shared) {
+    shared->lock([&](SOCKET socket, const addrinfo* info) {
+      if (bind(socket, info->ai_addr, (int)info->ai_addrlen) != 0) {
+        shared.reset();
+        return;
+      }
+
+      if (listen(socket, 0) != 0) {
+        shared.reset();
+        return;
+      }
+    });
+  }
+}
+
+std::shared_ptr<ReaderWriter> Socket::accept() const {
+  std::shared_ptr<Shared> out;
+  if (shared) {
+    shared->lock([&](SOCKET socket, const addrinfo*) {
+      if (socket != InvalidSocket && !errored(socket)) {
+        init();
+        auto accepted = ::accept(socket, 0, 0);
+        if (accepted != InvalidSocket) {
+          out = std::make_shared<Shared>(accepted);
+          out->setOptions();
+        }
+      }
+    });
+  }
+  return out;
+}
+
+bool Socket::isOpen() const {
+  if (shared) {
+    return shared->isOpen();
+  }
+  return false;
+}
+
+void Socket::close() const {
+  if (shared) {
+    shared->close();
+  }
+}
+
+std::shared_ptr<ReaderWriter> Socket::connect(const char* address,
+                                              const char* port,
+                                              uint32_t timeoutMillis) {
+  auto shared = Shared::create(address, port);
+  if (!shared) {
+    return nullptr;
+  }
+
+  std::shared_ptr<ReaderWriter> out;
+  shared->lock([&](SOCKET socket, const addrinfo* info) {
+    if (socket == InvalidSocket) {
+      return;
+    }
+
+    if (timeoutMillis == 0) {
+      if (::connect(socket, info->ai_addr, (int)info->ai_addrlen) == 0) {
+        out = shared;
+      }
+      return;
+    }
+
+    if (!setBlocking(socket, false)) {
+      return;
+    }
+
+    auto res = ::connect(socket, info->ai_addr, (int)info->ai_addrlen);
+    if (res == 0) {
+      if (setBlocking(socket, true)) {
+        out = shared;
+      }
+    } else {
+      const auto microseconds = timeoutMillis * 1000;
+
+      fd_set fdset;
+      FD_ZERO(&fdset);
+      FD_SET(socket, &fdset);
+
+      timeval tv;
+      tv.tv_sec = microseconds / 1000000;
+      tv.tv_usec = microseconds - static_cast<uint32_t>(tv.tv_sec * 1000000);
+      res = select(static_cast<int>(socket + 1), nullptr, &fdset, nullptr, &tv);
+      if (res > 0 && !errored(socket) && setBlocking(socket, true)) {
+        out = shared;
+      }
+    }
+  });
+
+  if (!out) {
+    return nullptr;
+  }
+
+  return out->isOpen() ? out : nullptr;
+}
+
+}  // namespace dap