net-base/socket.cc

// Copyright 2023 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net-base/socket.h"

#include <fcntl.h>
#include <linux/netlink.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

#include <memory>
#include <optional>
#include <utility>

#include <base/check_op.h>
#include <base/containers/span.h>
#include <base/functional/bind.h>
#include <base/functional/callback.h>
#include <base/logging.h>
#include <base/posix/eintr_wrapper.h>

#include "net-base/byte_utils.h"

namespace net_base {
namespace {

// Converts ssize_t to std::optional<size_t>. If |ignore_err| is true, then
// returns 0 even |size| is less than 0.
std::optional<size_t> ToOptionalSizeT(ssize_t size, bool ignore_err) {
  if (size >= 0) {
    return static_cast<size_t>(size);
  }
  if (ignore_err) {
    return 0;
  }
  return std::nullopt;
}

bool WouldBlock() {
  return errno == EAGAIN || errno == EWOULDBLOCK;
}

}  // namespace

// static
std::unique_ptr<Socket> Socket::Create(int domain, int type, int protocol) {
  base::ScopedFD fd(socket(domain, type, protocol));
  if (!fd.is_valid()) {
    return nullptr;
  }

  return std::unique_ptr<Socket>(new Socket(std::move(fd), type));
}

// static
std::unique_ptr<Socket> Socket::CreateFromFd(base::ScopedFD fd) {
  if (!fd.is_valid()) {
    return nullptr;
  }

  int type;
  socklen_t type_len = sizeof(type);
  if (getsockopt(fd.get(), SOL_SOCKET, SO_TYPE, &type, &type_len) < 0) {
    PLOG(ERROR) << "Could not get type of socket";
    return nullptr;
  }

  return std::unique_ptr<Socket>(new Socket(std::move(fd), type));
}

Socket::Socket(base::ScopedFD fd, int socket_type)
    : fd_(std::move(fd)), socket_type_(socket_type) {
  LOG_IF(FATAL, !fd_.is_valid()) << "the socket fd is invalid";
}
Socket::~Socket() = default;

int Socket::Get() const {
  return fd_.get();
}

void Socket::SetReadableCallback(base::RepeatingClosure callback) {
  watcher_ =
      base::FileDescriptorWatcher::WatchReadable(Get(), std::move(callback));
}

void Socket::UnsetReadableCallback() {
  watcher_ = nullptr;
}

// static
int Socket::Release(std::unique_ptr<Socket> socket) {
  if (socket == nullptr) {
    return -1;
  }

  return socket->fd_.release();
}

// Some system calls can be interrupted and return EINTR, but will succeed on
// retry.  The HANDLE_EINTR macro retries a call if it returns EINTR.  For a
// list of system calls that can return EINTR, see 'man 7 signal' under the
// heading "Interruption of System Calls and Library Functions by Signal
// Handlers".

std::unique_ptr<Socket> Socket::Accept(struct sockaddr* addr,
                                       socklen_t* addrlen) const {
  return CreateFromFd(
      base::ScopedFD(HANDLE_EINTR(accept(fd_.get(), addr, addrlen))));
}

bool Socket::Bind(const struct sockaddr* addr, socklen_t addrlen) const {
  return bind(fd_.get(), addr, addrlen) == 0;
}

bool Socket::Connect(const struct sockaddr* addr, socklen_t addrlen) const {
  return connect(fd_.get(), addr, addrlen) == 0;
}

bool Socket::GetSockName(struct sockaddr* addr, socklen_t* addrlen) const {
  return getsockname(fd_.get(), addr, addrlen) == 0;
}

bool Socket::Listen(int backlog) const {
  return listen(fd_.get(), backlog) == 0;
}

// NOLINTNEXTLINE(runtime/int)
std::optional<int> Socket::Ioctl(unsigned long request, void* argp) const {
  int res = HANDLE_EINTR(ioctl(fd_.get(), request, argp));
  if (res < 0) {
    return std::nullopt;
  }
  return res;
}

std::optional<size_t> Socket::RecvFrom(base::span<char> buf,
                                       int flags,
                                       struct sockaddr* src_addr,
                                       socklen_t* addrlen) const {
  return RecvFrom(base::as_writable_bytes(buf), flags, src_addr, addrlen);
}

std::optional<size_t> Socket::RecvFrom(base::span<uint8_t> buf,
                                       int flags,
                                       struct sockaddr* src_addr,
                                       socklen_t* addrlen) const {
  ssize_t res = HANDLE_EINTR(
      recvfrom(fd_.get(), buf.data(), buf.size(), flags, src_addr, addrlen));
  return ToOptionalSizeT(res, WouldBlock());
}

bool Socket::RecvStream(std::vector<uint8_t>* message) const {
  constexpr size_t kReadChunkSize = 4096;
  size_t offset = 0;

  while (true) {
    // Resize the buffer to hold more data.
    message->resize(offset + kReadChunkSize, 0);
    base::span<uint8_t> buf(message->data() + offset, kReadChunkSize);
    std::optional<size_t> read_size =
        RecvFrom(buf, MSG_DONTWAIT, nullptr, nullptr);
    if (!read_size.has_value()) {
      return false;
    }

    offset += *read_size;
    if (*read_size < kReadChunkSize) {
      break;
    }
  }

  // Shrink the buffer back to the exact size of the returned data.
  message->resize(offset, 0);
  return true;
}

bool Socket::RecvMessage(std::vector<uint8_t>* message) const {
  DCHECK(message) << "message is null";

  if (socket_type_ == SOCK_STREAM) {
    return RecvStream(message);
  }

  // Determine the amount of data currently waiting.
  const size_t kFakeReadByteCount = 1;
  std::vector<uint8_t> fake_read(kFakeReadByteCount);
  const std::optional<size_t> read_size =
      RecvFrom(fake_read, MSG_TRUNC | MSG_PEEK, nullptr, nullptr);
  if (!read_size.has_value()) {
    return false;
  }

  // Read the data that was waiting when we did our previous read.
  message->resize(*read_size, 0);
  return RecvFrom(*message, 0, nullptr, nullptr) == *read_size;
}

std::optional<size_t> Socket::Send(base::span<const char> buf,
                                   int flags) const {
  return Send(base::as_bytes(buf), flags);
}

std::optional<size_t> Socket::Send(base::span<const uint8_t> buf,
                                   int flags) const {
  ssize_t res = HANDLE_EINTR(send(fd_.get(), buf.data(), buf.size(), flags));
  return ToOptionalSizeT(res, WouldBlock());
}

std::optional<size_t> Socket::SendTo(base::span<const char> buf,
                                     int flags,
                                     const struct sockaddr* dest_addr,
                                     socklen_t addrlen) const {
  return SendTo(base::as_bytes(buf), flags, dest_addr, addrlen);
}

std::optional<size_t> Socket::SendTo(base::span<const uint8_t> buf,
                                     int flags,
                                     const struct sockaddr* dest_addr,
                                     socklen_t addrlen) const {
  ssize_t res = HANDLE_EINTR(
      sendto(fd_.get(), buf.data(), buf.size(), flags, dest_addr, addrlen));
  return ToOptionalSizeT(res, WouldBlock());
}

bool Socket::SetReceiveBuffer(int size) const {
  // Note: kernel will set buffer to 2*size to allow for struct skbuff overhead.
  return SetSockOpt(SOL_SOCKET, SO_RCVBUFFORCE, byte_utils::AsBytes(size));
}

bool Socket::SetSockOpt(int level,
                        int optname,
                        base::span<const uint8_t> opt_bytes) const {
  return setsockopt(fd_.get(), level, optname, opt_bytes.data(),
                    static_cast<socklen_t>(opt_bytes.size())) == 0;
}

std::unique_ptr<Socket> SocketFactory::Create(int domain,
                                              int type,
                                              int protocol) {
  return Socket::Create(domain, type, protocol);
}

std::unique_ptr<Socket> SocketFactory::CreateNetlink(
    int netlink_family,
    uint32_t netlink_groups_mask,
    std::optional<int> receive_buffer_size) {
  auto socket = Create(PF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, netlink_family);
  if (!socket) {
    PLOG(ERROR) << "Failed to open netlink socket for family "
                << netlink_family;
    return nullptr;
  }

  if (receive_buffer_size) {
    if (!socket->SetReceiveBuffer(*receive_buffer_size)) {
      PLOG(WARNING) << "Failed to increase receive buffer size to "
                    << *receive_buffer_size << "b";
    }
  }

  struct sockaddr_nl addr;
  memset(&addr, 0, sizeof(addr));
  addr.nl_family = AF_NETLINK;
  addr.nl_groups = netlink_groups_mask;

  if (!socket->Bind(reinterpret_cast<struct sockaddr*>(&addr), sizeof(addr))) {
    PLOG(ERROR) << "Netlink socket bind failed for family " << netlink_family;
    return nullptr;
  }

  return socket;
}

std::ostream& operator<<(std::ostream& stream, const Socket& socket) {
  stream << "{fd: " << socket.Get() << "}";
  return stream;
}

}  // namespace net_base