// Copyright 2019 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 "quiche/quic/masque/masque_utils.h"

#include <cstdint>
#include <cstring>
#include <ostream>
#include <string>
#include <utility>

#include "absl/strings/escaping.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
#include "quiche/quic/core/quic_data_writer.h"
#include "quiche/quic/core/quic_versions.h"
#include "quiche/quic/platform/api/quic_ip_address.h"
#include "quiche/quic/platform/api/quic_logging.h"
#include "quiche/common/platform/api/quiche_command_line_flags.h"
#include "quiche/common/platform/api/quiche_logging.h"

#if defined(__linux__)
#include <fcntl.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/sockios.h>
#include <sys/ioctl.h>
#endif  // defined(__linux__)

#include "absl/cleanup/cleanup.h"

DEFINE_QUICHE_COMMAND_LINE_FLAG(
    std::string, tap_bridge_interface, "",
    "Bridge tap interfaces created by CONNECT-ETHERNET mode to be bridged to "
    "the specified interface, if any.");

namespace quic {

ParsedQuicVersionVector MasqueSupportedVersions() {
  ParsedQuicVersionVector versions;
  for (const ParsedQuicVersion& version : AllSupportedVersions()) {
    // Use all versions that support IETF QUIC except QUICv2.
    if (version.UsesHttp3() && !version.AlpnDeferToRFCv1()) {
      QuicEnableVersion(version);
      versions.push_back(version);
    }
  }
  QUICHE_CHECK(!versions.empty());
  return versions;
}

std::string MasqueModeToString(MasqueMode masque_mode) {
  switch (masque_mode) {
    case MasqueMode::kInvalid:
      return "Invalid";
    case MasqueMode::kOpen:
      return "Open";
    case MasqueMode::kConnectIp:
      return "CONNECT-IP";
    case MasqueMode::kConnectEthernet:
      return "CONNECT-ETHERNET";
  }
  return absl::StrCat("Unknown(", static_cast<int>(masque_mode), ")");
}

std::ostream& operator<<(std::ostream& os, const MasqueMode& masque_mode) {
  os << MasqueModeToString(masque_mode);
  return os;
}

#if defined(__linux__)
int CreateTunInterface(const QuicIpAddress& client_address, bool server) {
  if (!client_address.IsIPv4()) {
    QUIC_LOG(ERROR) << "CreateTunInterface currently only supports IPv4";
    return -1;
  }
  // TODO(b/281517862): add test to validate O_NONBLOCK
  int tun_fd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
  if (tun_fd < 0) {
    QUIC_PLOG(ERROR) << "Failed to open clone device";
    return -1;
  }
  absl::Cleanup tun_fd_closer = [tun_fd] { close(tun_fd); };

  struct ifreq ifr = {};
  ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
  // If we want to pick a specific device name, we can set it via
  // ifr.ifr_name. Otherwise, the kernel will pick the next available tunX
  // name.
  int err = ioctl(tun_fd, TUNSETIFF, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "TUNSETIFF failed";
    return -1;
  }
  int ip_fd = socket(AF_INET, SOCK_DGRAM, 0);
  if (ip_fd < 0) {
    QUIC_PLOG(ERROR) << "Failed to open IP configuration socket";
    return -1;
  }
  absl::Cleanup ip_fd_closer = [ip_fd] { close(ip_fd); };

  struct sockaddr_in addr = {};
  addr.sin_family = AF_INET;
  // Local address, unused but needs to be set. We use the same address as the
  // client address, but with last byte set to 1.
  addr.sin_addr = client_address.GetIPv4();
  if (server) {
    addr.sin_addr.s_addr &= htonl(0xffffff00);
    addr.sin_addr.s_addr |= htonl(0x00000001);
  }
  memcpy(&ifr.ifr_addr, &addr, sizeof(addr));
  err = ioctl(ip_fd, SIOCSIFADDR, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCSIFADDR failed";
    return -1;
  }
  // Peer address, needs to match source IP address of sent packets.
  addr.sin_addr = client_address.GetIPv4();
  if (!server) {
    addr.sin_addr.s_addr &= htonl(0xffffff00);
    addr.sin_addr.s_addr |= htonl(0x00000001);
  }
  memcpy(&ifr.ifr_addr, &addr, sizeof(addr));
  err = ioctl(ip_fd, SIOCSIFDSTADDR, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCSIFDSTADDR failed";
    return -1;
  }
  if (!server) {
    // Set MTU, to 1280 for now which should always fit (fingers crossed)
    ifr.ifr_mtu = 1280;
    err = ioctl(ip_fd, SIOCSIFMTU, &ifr);
    if (err < 0) {
      QUIC_PLOG(ERROR) << "SIOCSIFMTU failed";
      return -1;
    }
  }

  err = ioctl(ip_fd, SIOCGIFFLAGS, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCGIFFLAGS failed";
    return -1;
  }
  ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);
  err = ioctl(ip_fd, SIOCSIFFLAGS, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCSIFFLAGS failed";
    return -1;
  }
  close(ip_fd);
  QUIC_DLOG(INFO) << "Successfully created TUN interface " << ifr.ifr_name
                  << " with fd " << tun_fd;
  std::move(tun_fd_closer).Cancel();
  return tun_fd;
}
#else
int CreateTunInterface(const QuicIpAddress& /*client_address*/,
                       bool /*server*/) {
  // Unsupported.
  return -1;
}
#endif  // defined(__linux__)

#if defined(__linux__)
int CreateTapInterface() {
  int tap_fd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
  if (tap_fd < 0) {
    QUIC_PLOG(ERROR) << "Failed to open clone device";
    return -1;
  }
  absl::Cleanup tap_fd_closer = [tap_fd] { close(tap_fd); };

  struct ifreq ifr = {};
  ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  // If we want to pick a specific device name, we can set it via
  // ifr.ifr_name. Otherwise, the kernel will pick the next available tapX
  // name.
  int err = ioctl(tap_fd, TUNSETIFF, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "TUNSETIFF failed";
    return -1;
  }

  QUIC_DLOG(INFO) << "Successfully created TAP interface " << ifr.ifr_name
                  << " with fd " << tap_fd;

  int sock_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
  if (sock_fd < 0) {
    QUIC_PLOG(ERROR) << "Error opening configuration socket";
    return -1;
  }
  absl::Cleanup sock_fd_closer = [sock_fd] { close(sock_fd); };

  err = ioctl(sock_fd, SIOCGIFINDEX, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCGIFINDEX failed";
  }
  int tap_ifindex = ifr.ifr_ifindex;

  ifr.ifr_mtu = 1280;
  err = ioctl(sock_fd, SIOCSIFMTU, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCSIFMTU failed";
    return -1;
  }

  err = ioctl(sock_fd, SIOCGIFFLAGS, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCGIFFLAGS failed";
    return -1;
  }
  ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);
  err = ioctl(sock_fd, SIOCSIFFLAGS, &ifr);
  if (err < 0) {
    QUIC_PLOG(ERROR) << "SIOCSIFFLAGS failed";
    return -1;
  }

  const std::string tap_bridge_interface =
      quiche::GetQuicheCommandLineFlag(FLAGS_tap_bridge_interface);

  if (!tap_bridge_interface.empty()) {
    if (tap_bridge_interface.size() >= IFNAMSIZ) {
      QUIC_LOG(ERROR) << "tap bridge interface size too long: "
                      << tap_bridge_interface.size();
      return -1;
    }
    strncpy(ifr.ifr_name, tap_bridge_interface.c_str(), IFNAMSIZ);
    ifr.ifr_ifindex = tap_ifindex;
    err = ioctl(sock_fd, SIOCBRADDIF, &ifr);
    if (err < 0) {
      QUIC_PLOG(ERROR) << "SIOCBRADDIF failed";
      return -1;
    }
  }

  std::move(tap_fd_closer).Cancel();
  return tap_fd;
}
#else
int CreateTapInterface() {
  // Unsupported.
  return -1;
}
#endif  // defined(__linux__)

std::string ComputeConcealedAuthContext(uint16_t signature_scheme,
                                        absl::string_view key_id,
                                        absl::string_view public_key,
                                        absl::string_view scheme,
                                        absl::string_view host, uint16_t port,
                                        absl::string_view realm) {
  QUIC_DVLOG(2) << "ComputeConcealedAuthContext: key_id=\"" << key_id
                << "\" public_key=" << absl::WebSafeBase64Escape(public_key)
                << " scheme=\"" << scheme << "\" host=\"" << host
                << "\" port=" << port << " realm=\"" << realm << "\"";
  std::string key_exporter_context;
  key_exporter_context.resize(
      sizeof(signature_scheme) + QuicDataWriter::GetVarInt62Len(key_id.size()) +
      key_id.size() + QuicDataWriter::GetVarInt62Len(public_key.size()) +
      public_key.size() + QuicDataWriter::GetVarInt62Len(scheme.size()) +
      scheme.size() + QuicDataWriter::GetVarInt62Len(host.size()) +
      host.size() + sizeof(port) +
      QuicDataWriter::GetVarInt62Len(realm.size()) + realm.size());
  QuicDataWriter writer(key_exporter_context.size(),
                        key_exporter_context.data());
  if (!writer.WriteUInt16(signature_scheme) ||
      !writer.WriteStringPieceVarInt62(key_id) ||
      !writer.WriteStringPieceVarInt62(public_key) ||
      !writer.WriteStringPieceVarInt62(scheme) ||
      !writer.WriteStringPieceVarInt62(host) || !writer.WriteUInt16(port) ||
      !writer.WriteStringPieceVarInt62(realm) || writer.remaining() != 0) {
    QUIC_LOG(FATAL) << "ComputeConcealedAuthContext failed";
  }
  return key_exporter_context;
}

std::string ConcealedAuthDataCoveredBySignature(
    absl::string_view signature_input) {
  return absl::StrCat(std::string(64, 0x20), "HTTP Concealed Authentication",
                      std::string(1, 0x00), signature_input);
}

}  // namespace quic