// 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 <fcntl.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/ioctl.h>

namespace quic {

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

QuicConfig MasqueEncapsulatedConfig() {
  QuicConfig config;
  config.SetMaxPacketSizeToSend(kMasqueMaxEncapsulatedPacketSize);
  return config;
}

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";
  }
  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;
}

int CreateTunInterface(const QuicIpAddress& client_address, bool server) {
  if (!client_address.IsIPv4()) {
    QUIC_LOG(ERROR) << "CreateTunInterface currently only supports IPv4";
    return -1;
  }
  int tun_fd = open("/dev/net/tun", O_RDWR);
  int ip_fd = -1;
  do {
    if (tun_fd < 0) {
      QUIC_PLOG(ERROR) << "Failed to open clone device";
      break;
    }
    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";
      break;
    }
    ip_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (ip_fd < 0) {
      QUIC_PLOG(ERROR) << "Failed to open IP configuration socket";
      break;
    }
    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";
      break;
    }
    // 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";
      break;
    }
    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";
        break;
      }
    }

    err = ioctl(ip_fd, SIOCGIFFLAGS, &ifr);
    if (err < 0) {
      QUIC_PLOG(ERROR) << "SIOCGIFFLAGS failed";
      break;
    }
    ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);
    err = ioctl(ip_fd, SIOCSIFFLAGS, &ifr);
    if (err < 0) {
      QUIC_PLOG(ERROR) << "SIOCSIFFLAGS failed";
      break;
    }
    close(ip_fd);
    QUIC_DLOG(INFO) << "Successfully created TUN interface " << ifr.ifr_name
                    << " with fd " << tun_fd;
    return tun_fd;
  } while (false);
  if (tun_fd >= 0) {
    close(tun_fd);
  }
  if (ip_fd >= 0) {
    close(ip_fd);
  }
  return -1;
}

}  // namespace quic