Support creating mojo peer connections from named pipes.

mojo/edk/embedder/named_platform_handle_utils_posix.cc

+// Copyright 2016 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 "mojo/edk/embedder/named_platform_handle_utils.h"
+
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+#include "mojo/edk/embedder/named_platform_handle.h"
+
+namespace mojo {
+namespace edk {
+namespace {
+
+// The maximum length of the name of a socket for MODE_NAMED_SERVER or
+// MODE_NAMED_CLIENT if you want to pass in your own socket.
+// The standard size on linux is 108, mac is 104. To maintain consistency
+// across platforms we standardize on the smaller value.
+const size_t kMaxSocketNameLength = 104;
+
+// This function fills in |unix_addr| with the appropriate data for the socket,
+// and sets |unix_addr_len| to the length of the data therein.
+// Returns true on success, or false on failure (typically because |handle.name|
+// violated the naming rules).
+bool MakeUnixAddr(const NamedPlatformHandle& handle,
+                  struct sockaddr_un* unix_addr,
+                  size_t* unix_addr_len) {
+  DCHECK(unix_addr);
+  DCHECK(unix_addr_len);
+  DCHECK(handle.is_valid());
+
+  // We reject handle.name.length() == kMaxSocketNameLength to make room for the
+  // NUL terminator at the end of the string.
+  if (handle.name.length() >= kMaxSocketNameLength) {
+    LOG(ERROR) << "Socket name too long: " << handle.name;
+    return false;
+  }
+
+  // Create unix_addr structure.
+  memset(unix_addr, 0, sizeof(struct sockaddr_un));
+  unix_addr->sun_family = AF_UNIX;
+  strncpy(unix_addr->sun_path, handle.name.c_str(), kMaxSocketNameLength);
+  *unix_addr_len =
+      offsetof(struct sockaddr_un, sun_path) + handle.name.length();
+  return true;
+}
+
+// This function creates a unix domain socket, and set it as non-blocking.
+// If successful, this returns a ScopedPlatformHandle containing the socket.
+// Otherwise, this returns an invalid ScopedPlatformHandle.
+ScopedPlatformHandle CreateUnixDomainSocket(bool needs_connection) {
+  // Create the unix domain socket.
+  PlatformHandle socket_handle(socket(AF_UNIX, SOCK_STREAM, 0));
+  socket_handle.needs_connection = needs_connection;
+  ScopedPlatformHandle handle(socket_handle);
+  if (!handle.is_valid()) {
+    PLOG(ERROR) << "Failed to create AF_UNIX socket.";
+    return ScopedPlatformHandle();
+  }
+
+  // Now set it as non-blocking.
+  if (!base::SetNonBlocking(handle.get().handle)) {
+    PLOG(ERROR) << "base::SetNonBlocking() failed " << handle.get().handle;
+    return ScopedPlatformHandle();
+  }
+  return handle;
+}
+
+}  // namespace
+
+ScopedPlatformHandle CreateClientHandle(
+    const NamedPlatformHandle& named_handle) {
+  if (!named_handle.is_valid())
+    return ScopedPlatformHandle();
+
+  struct sockaddr_un unix_addr;
+  size_t unix_addr_len;
+  if (!MakeUnixAddr(named_handle, &unix_addr, &unix_addr_len))
+    return ScopedPlatformHandle();
+
+  ScopedPlatformHandle handle = CreateUnixDomainSocket(false);
+  if (!handle.is_valid())
+    return ScopedPlatformHandle();
+
+  if (HANDLE_EINTR(connect(handle.get().handle,
+                           reinterpret_cast<sockaddr*>(&unix_addr),
+                           unix_addr_len)) < 0) {
+    PLOG(ERROR) << "connect " << named_handle.name;
+    return ScopedPlatformHandle();
+  }
+
+  return handle;
+}
+
+ScopedPlatformHandle CreateServerHandle(const NamedPlatformHandle& named_handle,
+                                        bool enforce_uniqueness) {
+  CHECK(!enforce_uniqueness);
+  if (!named_handle.is_valid())
+    return ScopedPlatformHandle();
+
+  // Make sure the path we need exists.
+  base::FilePath socket_dir = base::FilePath(named_handle.name).DirName();
+  if (!base::CreateDirectory(socket_dir)) {
+    LOG(ERROR) << "Couldn't create directory: " << socket_dir.value();
+    return ScopedPlatformHandle();
+  }
+
+  // Delete any old FS instances.
+  if (unlink(named_handle.name.c_str()) < 0 && errno != ENOENT) {
+    PLOG(ERROR) << "unlink " << named_handle.name;
+    return ScopedPlatformHandle();
+  }
+
+  struct sockaddr_un unix_addr;
+  size_t unix_addr_len;
+  if (!MakeUnixAddr(named_handle, &unix_addr, &unix_addr_len))
+    return ScopedPlatformHandle();
+
+  ScopedPlatformHandle handle = CreateUnixDomainSocket(true);
+  if (!handle.is_valid())
+    return ScopedPlatformHandle();
+
+  // Bind the socket.
+  if (bind(handle.get().handle, reinterpret_cast<const sockaddr*>(&unix_addr),
+           unix_addr_len) < 0) {
+    PLOG(ERROR) << "bind " << named_handle.name;
+    return ScopedPlatformHandle();
+  }
+
+  // Start listening on the socket.
+  if (listen(handle.get().handle, SOMAXCONN) < 0) {
+    PLOG(ERROR) << "listen " << named_handle.name;
+    unlink(named_handle.name.c_str());
+    return ScopedPlatformHandle();
+  }
+  return handle;
+}
+
+}  // namespace edk
+}  // namespace mojo