oxen-core/src/device/io_ledger_tcp.cpp

#include "io_ledger_tcp.hpp"
#include "common/oxen.h"
#include <array>
#include <boost/endian/conversion.hpp>
#include <cstring>
#include <stdexcept>
#include "epee/misc_log_ex.h"

extern "C" {
#ifdef _WIN32
#  include <ws2tcpip.h>
#  include <winsock2.h>
#else
#  include <arpa/inet.h>
#  include <netdb.h>
#  include <netinet/in.h>
#  include <sys/socket.h>
#endif
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>
}

#undef OXEN_DEFAULT_LOG_CATEGORY
#define OXEN_DEFAULT_LOG_CATEGORY "device.io"

namespace hw::io {

static std::string to_string(const addrinfo* a) {
  std::array<char, INET6_ADDRSTRLEN> buf;
  std::string addr;
#ifdef _WIN32
  unsigned long buflen = buf.size();
  if (auto rc = WSAAddressToString(a->ai_addr, a->ai_addrlen, nullptr, buf.data(), &buflen);
      rc == 0)
    addr = buf.data();
  else
    addr = "[error:"s + std::to_string(rc) + "]";
#else
  if (inet_ntop(a->ai_family, a->ai_addr, buf.data(), buf.size()))
    addr = buf.data();
  else
    addr = "[error:"s + strerror(errno) + "]";
#endif
  if (a->ai_family == AF_INET)
    (addr += ':') += std::to_string(reinterpret_cast<sockaddr_in*>(a->ai_addr)->sin_port);
  else if (a->ai_family == AF_INET6)
    (addr += ':') += std::to_string(reinterpret_cast<sockaddr_in6*>(a->ai_addr)->sin6_port);
  return addr;
}

void ledger_tcp::connect() {
  disconnect();

  int fd = socket(AF_INET, SOCK_STREAM, 0);
  if (fd < 0)
    throw std::runtime_error{"Failed to open socket: "s + strerror(errno)};
  auto closer = oxen::defer([&] { close(fd); });

#ifdef _WIN32
  unsigned long blocking_param = 1; // 1 = make non-blocking, 0 = blocking
  if (auto result = ioctlsocket(fd, FIONBIO, &blocking_param);
      result != NO_ERROR)
    throw std::runtime_error{"ioctlsocket failed with error: " + std::to_string(result)};
#else
  if (-1 == fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK))
    throw std::runtime_error{"Failed to set socket non-blocking: "s + strerror(errno)};
#endif

  addrinfo* addr;
  if (int rc = getaddrinfo(host.data(), port.data(), nullptr, &addr);
      rc != 0)
    throw std::runtime_error{"Failed to resolve " + host + ":" + port + ": " + gai_strerror(rc)};
  auto addr_free = oxen::defer([&] { freeaddrinfo(addr); });

  const addrinfo* a;
  bool connected = false;
  const char* err = "An unknown error occurred";
  for (a = addr; a && !connected; a = a->ai_next) {
    MDEBUG("Attempting to connect to " << to_string(a));
    int rc = ::connect(fd, a->ai_addr, a->ai_addrlen);
    connected = rc == 0;
    if (rc == -1) {
      if (errno == EINPROGRESS) {
        timeval timeo;
        timeo.tv_sec = std::chrono::duration_cast<std::chrono::seconds>(connect_timeout).count();
        timeo.tv_usec = (connect_timeout % 1s).count();
        fd_set myset;
        FD_ZERO(&myset); 
        FD_SET(fd, &myset); 
        rc = select(fd + 1, nullptr, &myset, nullptr, &timeo); 
        if (rc > 0)
          connected = true;
        else if (rc == 0)
          err = "Connection timed out";
        else
          err = strerror(errno);
      } else {
        err = strerror(errno);
      }
    }
  }
  if (!connected)
    throw std::runtime_error{"Failed to connect to " + host + ":" + port + ": " + err};

  MDEBUG("Connected to " << to_string(a));

#ifdef _WIN32
  blocking_param = 0;
  if (auto result = ioctlsocket(fd, FIONBIO, &blocking_param);
      result != NO_ERROR)
    throw std::runtime_error{"ioctlsocket failed with error: " + std::to_string(result)};
#else
  if (-1 == fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK))
    throw std::runtime_error{"Failed to set socket back to blocking: "s + strerror(errno)};
#endif

  timeval timeo;
  timeo.tv_sec = std::chrono::duration_cast<std::chrono::seconds>(exchange_timeout).count();
  timeo.tv_usec = (exchange_timeout % 1s).count();

  // The reinterpret_cast here is needed for Windows's shitty imitation of the api
  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, reinterpret_cast<const char*>(&timeo), sizeof(timeo));
  setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, reinterpret_cast<const char*>(&timeo), sizeof(timeo));

  sockfd = std::make_unique<int>(fd);
  closer.cancel();
}

void ledger_tcp::disconnect() {
  if (!sockfd)
    return;

  close(*sockfd);
  sockfd.reset();
}

ledger_tcp::~ledger_tcp() {
  disconnect();
}

bool ledger_tcp::connected() const {
  return (bool) sockfd;
}

void full_read(int fd, unsigned char* to, int size) {
  while (size > 0) {
    auto read_size = read(fd, to, size);
    if (read_size == -1)
      throw std::runtime_error{"Failed to read from hardware wallet socket: "s + strerror(errno)};
    size -= read_size;
    to += read_size;
  }
}

void full_write(int fd, const unsigned char* from, int size) {
  while (size > 0) {
    auto wrote = write(fd, from, size);
    if (wrote == -1)
      throw std::runtime_error{"Failed to write to hardware wallet socket: "s + strerror(errno)};
    size -= wrote;
    from += wrote;
  }
}

int ledger_tcp::exchange(const unsigned char* command, unsigned int cmd_len, unsigned char* response, unsigned int max_resp_len, bool user_input) {
  if (!sockfd)
    throw std::runtime_error{"Unable to exchange data with hardware wallet: not connected"};

  // Sending: [SIZE][DATA], where SIZE is a uint32_t in network order
  uint32_t size = boost::endian::native_to_big(cmd_len);
  const unsigned char* size_bytes = reinterpret_cast<const unsigned char*>(&size);
  full_write(*sockfd, size_bytes, 4);
  full_write(*sockfd, command, cmd_len);


  // Receiving: [SIZE][DATA], where SIZE is the length of DATA minus 2 (WTF) because the last two
  // bytes of DATA are a 2-byte, u16 status code and... therefore not... included.  Good job, Ledger
  // devs.
  full_read(*sockfd, reinterpret_cast<unsigned char*>(&size), 4);
  auto data_size = boost::endian::big_to_native(size) + 2;

  if (data_size > max_resp_len)
    throw std::runtime_error{"Hardware wallet returned unexpectedly large response: got " +
      std::to_string(data_size) + " bytes, expected <= " + std::to_string(max_resp_len)};

  full_read(*sockfd, response, data_size);

  return data_size;
}

}